CT Angiographic Features of Symptom-Producing Plaque in Moderate-Grade Carotid Artery Stenosis

BACKGROUND AND PURPOSE:Emerging evidence indicates that plaque imaging can improve stroke risk stratification in patients with carotid artery atherosclerosis. We studied the association between soft and hard (calcified) plaque thickness measurements on CTA and symptomatic disease status (ipsilateral stroke or TIA) in patients with moderate-grade carotid artery stenosis.MATERIALS AND METHODS:We measured soft-plaque and hard-plaque thickness on CTA axial source images in each carotid artery plaque in subjects with NASCET 50%–69% ICA stenosis. We used logistic regression and receiver operating characteristic analyses to assess the strength of the association between thickness measurements and prior stroke or TIA.RESULTS:Twenty of 72 vessels studied (27.7%) had ischemic symptoms ipsilateral to the side of moderate-grade carotid stenosis. Each 1-mm increase in soft plaque resulted in a 3.7 times greater odds of a prior ipsilateral ischemic event (95% CI, 1.9–7.2). Conversely, for each 1-mm increase in hard plaque, the odds of being symptomatic decreased by approximately 80% (OR, 0.22; 95% CI, 0.10%–0.48%). Receiver operating characteristic analysis showed an area under the curve of 0.88 by using soft-plaque thickness measurements to discriminate between asymptomatic and symptomatic plaques. Sensitivity and specificity were optimized by using a maximum soft-plaque thickness of 2.2 mm, which provided a sensitivity of 85% and a specificity of 83%.CONCLUSIONS:Simple CTA plaque-thickness measurements might differentiate symptomatic and asymptomatic moderate-grade carotid artery plaque. With further prospective validation, CTA plaque measures could function as an easily implementable tool for risk stratification in carotid artery disease.

Moderate-grade carotid artery stenosis is a risk factor for stroke, with pooled analysis from randomized controlled trials, including the European Carotid Surgery Trial, NASCET, and Veterans Affairs Symptomatic Trial, suggesting that unoperated patients with moderate-grade stenosis face up to a 20% 5-year risk of stroke.¹ Data pooled from these randomized controlled trials have also shown a modest stroke-risk-reduction benefit from carotid endarterectomy in patients with 50%–69% extracranial ICA stenosis.¹ However, the validity of these data has been questioned in the years since these trials were performed secondary to recent improvements in medical therapy, which have substantially reduced annual stroke rates in patients with carotid disease.^2,3 Consequently, there has been significant recent effort to develop new imaging markers that can identify patients with carotid artery disease at highest risk for stroke beyond luminal-diameter stenosis measurements.The 2 main pathophysiologic mechanisms underlying stroke risk in carotid artery disease are the propensity of plaque to locally embolize^4,5 and downstream hemodynamic compromise (low flow).^4,6,7 Although hypoperfusion and resultant slow flow from carotid disease likely play a role in a subset of strokes occurring in carotid stenosis, plaque instability causing distal embolus may be a relatively more influential etiologic factor for stroke in carotid disease in general.⁸ Although multisequence MR imaging characterization of plaque has allowed the in vivo discrimination of high-risk plaque tissue elements,^9–11 its use in clinical practice has been limited, given the time, expense, and challenge of performing multisequence carotid plaque MR imaging by using a dedicated carotid coil. CTA-based measurements of soft and hard (calcified) plaque determined on axial CTA source images have recently been proposed as potential simple alternative markers of vulnerable plaque in high-grade ICA stenosis.^12,13 Because plaque volumes are relatively smaller in moderate-grade stenosis, it is unclear to what extent such techniques are capable of identifying symptom-producing plaque in this group of patients in whom optimal treatment guidelines are controversial. Therefore, we used a cross-sectional study design to assess the association between plaque thickness measurements obtained from neck CTA and previous stroke or TIA in patients with moderate-grade ICA stenosis.     

Detection of Carotid Artery Stenosis: A Comparison between 2 Unenhanced MRAs and Dual-Source CTA

BACKGROUND AND PURPOSE:Dual-source CTA and black-blood MRA are recently developed techniques for evaluating carotid stenosis. The purpose of this study was to compare dual-source CTA with black-blood MRA and conventional TOF MRA in both detecting carotid stenosis by using DSA as a reference standard and demonstrating plaque morphology.MATERIALS AND METHODS:Thirty patients with suspected carotid artery stenosis underwent unenhanced MRA by using black-blood and TOF MRA and dual-source CTA. Source images from unenhanced MRAs and dual-source CTA were reconstructed with MIP or curved planar reconstruction. The degree of carotid artery stenosis was measured, and plaque surface morphology at the stenosis was analyzed and compared among different techniques.RESULTS:Good correlation was observed for measuring the degree of carotid stenosis among dual-source CTA, black-blood MRA, TOF MRA, and DSA. Sensitivity and specificity for detecting severe stenosis were 100% and 97% with dual-source CTA, 100% and 95% with black-blood MRA, and 79% and 95% with TOF MRA. None of the 3 technologies resulted in stenosis of <50% being overestimated. Plaque surface irregularity or ulceration was more frequently detected with dual-source CTA and black-blood MRA than with TOF MRA and DSA.CONCLUSIONS:This preliminary study shows that black-blood MRA is a promising technique, comparable with dual-source CTA and DSA, but better than TOF MRA, in the evaluation of carotid stenosis. Unlike dual-source CTA, black-blood MRA requires no intravenous contrast or radiation.

Carotid artery atherosclerosis is a major cause of ischemic cerebrovascular disease.^1,2 Measurement of carotid stenosis and demonstration of plaque morphology are critical for the management of patients with carotid atherosclerosis. DSA is the current reference standard for evaluating carotid artery stenosis. The diagnostic role of DSA has largely been replaced, however, by noninvasive techniques such as sonography, CTA, and MRA.Sonography has been the most commonly performed technique but may be restricted by its operator dependence and limited coverage. CTA is another widely used technique for the evaluation of carotid artery stenosis with high accuracy.³ Dual-source CTA (DSCTA) uses 2 x-ray sources and 2 detectors at the same time. With this technique, 2 images can be simultaneously acquired with different tube voltages; this feature has been shown to be an advantage for the evaluation of densely calcified carotid stenosis.^4,5 Contrast-enhanced MRA has been established as an alternative for carotid imaging with a diagnostic accuracy similar to that of CTA.^6,7 Both CTA and contrast-enhanced MRA use contrast media and are restricted in patients with impaired renal function, and CTA also requires ionizing radiation. As a result, unenhanced MRA without gadolinium is a desirable alternative, especially in patients with renal failure. Conventional TOF MRA has been widely used in clinical practice for carotid visualization, but it is limited by local reduction of signal intensity related to slow and turbulent flow and also prolonged imaging time.⁸ T2-weighted black-blood MRA (BB MRA) is a newly developed technique showing potential in the evaluation of both the lumen and the wall of the carotid artery after optimal suppression of the signal from flowing blood.^9,10 Few studies, to our knowledge however, have compared DSCTA with BB MRA and conventional TOF MRA in evaluating carotid stenosis.The aim of this study was to prospectively and intraindividually compare these 2 unenhanced MRA methods with DSCTA in detecting carotid artery stenosis by using DSA as the standard of reference and in demonstrating plaque morphology.     

Acute Bleeding in the Head and Neck: Angiographic Findings and Endovascular Management

BACKGROUND AND PURPOSE:Life-threatening bleeding in the head and neck requires urgent management. This study evaluated the angiographic findings related to head and neck bleeding and presents endovascular management techniques.MATERIAL AND METHODS:Sixty-one consecutive patients who presented with acute bleeding in the head and neck areas and subsequently underwent endovascular therapy between January 2002 and October 2012 were included in our study. We evaluated the angiographic findings, techniques, and results of endovascular management.RESULTS:Contrast leakage (n = 10), pseudoaneurysm (n = 20), or both (n = 10) were the most common life-threatening angiographic findings (66%) and were the foci of immediate embolization or endoluminal vessel reconstruction. Seventeen patients (28%) had hypervascular staining of the tumor or mucosa, and 4 patients (6%) did not have any abnormal findings. The acute bleeding was successfully controlled by endovascular management according to the bleeding foci. Carotid arterial lesions, so-called “carotid blowout,” required reconstructive or deconstructive therapy. Bleeding of the external carotid artery required specific branch embolization by a combination of various embolic materials. No procedure-related complications occurred except in 1 patient who experienced acute infarction caused by thromboemboli from the covered stent. Seventeen patients (28%) were retreated due to rebleeding after the mean 20-month follow-up.CONCLUSIONS:Contrast leakage or a pseudoaneurysm or both seen on angiography are active bleeding foci and targets for therapy in patients with acute bleeding in the head and neck area. Despite different bleeding-control strategies according to vessel involvement, endovascular treatment is safe and effective for controlling hemorrhage.

Acute bleeding in the head and neck area occurs due to various causes and often is a life-threatening situation. If conservative management is unsuccessful, conventional angiography followed by endovascular treatment can have a major role in localizing the source of the bleeding and obliterating bleeding foci, thus leading to immediate and complete hemostasis.Head and neck cancers are the main cause of intractable hemorrhage from local tumor irradiation or spontaneous tumor bleeding.^1–5 Acute rupture of irradiated, large vessels is a rare but life-threatening therapy complication.⁶ In addition to tumor-related bleeding, there is also iatrogenic bleeding related to surgical procedures or craniomaxillofacial trauma, which can also lead to intractable, life-threatening bleeding.The distribution of bleeding foci is diverse and can range from large vessels, such as the internal or common carotid arteries, to small branches of the external carotid artery (ECA). Identification of the lesion location is mandatory when performing an angiographic procedure and analyzing the angiographic findings because the exact localization of the bleeding site is associated with immediate bleeding control.The endovascular management of bleeding arising from the extracranial carotid arteries, the so-called “carotid blowout syndrome,” has been extensively reported.^7–14 However, to our knowledge, the exact extent of the carotid blowout syndrome (CBS) in patients with acute bleeding has not been evaluated or compared with that of patients without CBS, despite the completely different application of endovascular hemostatic techniques for CBS versus non-CBS lesions. Therefore, we present our experience of endovascular management of 61 patients with acute head and neck bleeding from a variety of causes, with an emphasis on the angiographic results and the subsequent endovascular management according to the angiographic findings. We also compared the differences between patients with and without tumors related to the causative angiographic features, treatment outcome, and rate of endovascular retreatment.     

Advantages of 70-kV CT Angiography for the Visualization of the Adamkiewicz Artery: Comparison with 120-kV Imaging

BACKGROUND AND PURPOSE:Preprocedural identification of the Adamkiewicz artery is crucial in patients with aortic diseases. This study aimed to compare 70-kV CTA with conventional 120-kV CTA for the identification of the Adamkiewicz artery, examining differences in radiation dose and image quality.MATERIALS AND METHODS:We retrospectively analyzed 2 equal groups of 60 patients who had undergone 70-kV or 120-kV CTA to detect the Adamkiewicz artery before aortic repair. Size-specific dose estimate, the CT number of the aorta, and the contrast-to-noise ratio of the anterior spinal artery to the spinal cord were recorded. Furthermore, detectability of the Adamkiewicz artery was evaluated by using a 4-point continuity score (3, definite to 0, undetectable).RESULTS:There was significantly lower radiation exposure with 70-kV CTA than 120-kV CTA (median size-specific dose estimate, 23.1 versus 61.3 mGy, respectively; P < .001). CT number and contrast-to-noise ratio were both significantly higher in the 70-kV CTA group than the 120-kV group (999.1 HU compared with 508.7 HU, and 5.6 compared with 3.4, respectively; P < .001 for both). Detectability of the Adamkiewicz artery was not impaired in the 70-kV CTA group (90.0% versus 83.3% in the 120-kV group, P = .28). Moreover, the Adamkiewicz artery was detected with greater confidence with 70-kV CTA, reflected by a significantly superior continuity score (median, 3) compared with 120-kV CTA (median, 2; P = .001).CONCLUSIONS:Seventy-kilovolt CTA has substantial advantages for the identification of the Adamkiewicz artery before aortic repair, with a significantly lower radiation exposure and superior image quality than 120-kV CTA.

Spinal cord ischemia is a serious complication of surgical and endovascular stent-graft repair of thoracic or thoracoabdominal aortic aneurysms and aortic dissection.¹ Preservation of spinal cord blood supply, especially from the Adamkiewicz artery (AKA) and its tributary the critical segmental artery (CSA) during the procedure is mandatory to prevent neurologic complications.^2,3 Thus, accurate preprocedural knowledge of the anatomy of the AKA and CSA is crucial, particularly in surgical repair.⁴Recently, CTA has been used for noninvasive identification of the AKA^5,6 in place of invasive selective spinal angiography. However, the anatomic features of the AKA—a small vessel surrounded by osseous structures—may frequently be obscured in the contrast-to-noise ratio (CNR) of the spinal vasculature.⁷ A higher contrast-to-noise ratio in spinal CTA has previously been achieved with a high tube current–time product with a slow rotation speed and a small helical pitch to reduce image noise,⁸ and CTA with intra-arterial injection has been used to increase the contrast of the vessel.^7,9,10 Consequently, the detection rate of the AKA has been improved to 85%–100%^7,8,10–12; however, these techniques require either high radiation exposure or the insertion of a pigtail catheter into the pathologic aorta.⁸Seventy-kilovolt CT can substantially increase vascular iodine enhancement compared with conventional 120-kV imaging because the effective photon energy achieved with a 70-kV scan lies in the range of maximum absorption close to the K-edge of iodine (33.2 keV).^13,14 The mean CT number in the aorta with 70-kV CTA is reported to be approximately 700 HU, even with intravenous injection,¹⁴ which approaches the attenuation in the aorta with intra-arterial injection in 120-kV imaging.⁷ Moreover, radiation exposure is significantly reduced with lower voltage scanning.^14–16 We hypothesized that 70-kV CTA would be associated with superior AKA visualization, with high vessel attenuation and lower radiation exposure. The aim of this study was to compare 70-kV CTA with conventional 120-kV imaging for the identification of the AKA and the CSA regarding the radiation dose and qualitative and quantitative image quality.     

Carotid CTA: Radiation Exposure and Image Quality with the Use of Attenuation-Based,Automated Kilovolt Selection

BACKGROUND AND PURPOSE:CTA is considered the imaging modality of choice in evaluating the supraaortic vessels in many institutions, but radiation exposure remains a matter of concern. The objective of the study was to evaluate a fully automated, attenuation-based kilovolt selection algorithm in carotid CTA in respect to radiation dose and image quality compared with a standard 120-kV protocol.MATERIALS AND METHODS:Ninety-eight patients were included: 53 examinations (patient age, 66 ± 12 years) were performed by use of automated adaption of tube potential (80–140 kV) on the basis of the attenuation profile of the scout scan (study group), and 45 examinations (patient age, 67 ± 11 years) were performed by use of a standard 120-kV protocol (control group). CT dose index volume and dose-length product were recorded from the examination protocol. Image quality was assessed by ROI measurements and calculations of SNR and contrast-to-noise ratio. Subjective image quality was evaluated by 2 observers with the use of a 4-point scale (3, excellent; 0, not diagnostic).RESULTS:Subjective image quality was rated as “excellent” or “good” in all examinations (study group, 2.8; control group, 2.8). The algorithm automatically selected 100 kV in 47% and 80 kV in 34%; 120 kV was retained in 19%. An elevation to 140 kV did not occur. Compared with the control group, overall CT dose index volume reduction was 33.7%; overall dose-length product reduction was 31.5%. In the low-kilovolt scans, image noise and mean attenuation of ROIs inside the carotid arteries were significantly higher than in 120-kV scans, resulting in a constant or increased (80-kV group) contrast-to-noise ratio.CONCLUSIONS:The attenuation-based, kilovolt selection algorithm enables a dose reduction of >30% in carotid artery CTA while maintaining contrast-to-noise ratio and subjective image quality at adequate levels.

CT angiography is recommended as a second-line imaging technique in patients with extracranial carotid artery disease after screening with Doppler sonography.¹ As the result of rapid technological evolution, the number of CT examinations is still rising,² even with the significant medical x-ray exposure^2,3 and the increasing awareness of the potential risks of even relatively low radiation doses^2,4—especially in usage as a screening tool⁵ or in serial use.⁶ Biologic experiments have demonstrated that the number of DNA double-strand breaks is closely related to the applied dose.^3,7Several techniques for CT dose reduction, maintaining image quality on a diagnostic level, became a hot topic in clinical research.^8–11 Automated attenuation-based tube current modulation or so-called automatic exposure control techniques are widely used.^12,13 All major manufacturers provide iterative reconstruction algorithms, which are fast enough to be used in clinical practice and aim to compensate the increased image noise of low-dose CTA scans.^14,15Besides minimizing tube current, the reduction of the tube voltage is a potent option to reduce radiation dose. Such low-kilovolt protocols are used in cerebral perfusion CT in the evaluation of patients with stroke¹⁶ and in pediatric CT.¹⁷ In phantom¹⁸ as well as in clinical studies, it has been demonstrated that this technique can also be used in chest and abdominal imaging in adults.^19–24Lower tube voltage in CTA results in higher noise levels on one hand, but the attenuation of iodine is increased^25,26 on the other hand. This relationship must be considered when trying to reduce radiation exposure by use of low-kilovolt scanning and to maintain image quality.^24,27 The higher noise level in low-kilovolt scans will not be completely compensated by the higher iodine attenuation; therefore, additional adjustments of the tube current (milliampere setting) are necessary. Optimal manual adjustment of these parameters is complex, which prevented low-kilovolt scanning from general use until now. New software solutions that automatically adjust the kilovolt and milliampere setting to the individual patient anatomy by the attenuation profile of the scout scan may overcome this limitation.²⁰In a previous study, significant dose reduction and higher attenuation profiles of the carotid arteries were reported but were limited in image quality at the level of the common carotid artery.²⁸In the present study, we aimed to evaluate the effects on radiation exposure and image quality in CTA of the carotid arteries by use of a commercially available automated tube voltage and tube current adaption software tool.     

Carotid Bulb Webs as a Cause of “Cryptogenic” Ischemic Stroke

BACKGROUND AND PURPOSE:Carotid webs are intraluminal shelf-like filling defects at the carotid bulb with recently recognized implications in patients with recurrent ischemic stroke. We sought to determine whether carotid webs are an under-recognized cause of “cryptogenic” ischemic stroke and to estimate their prevalence in the general population.MATERIALS AND METHODS:A retrospective review of neck CTA studies in young patients with cryptogenic stroke over the past 6 years (n = 33) was performed to determine the prevalence of carotid webs compared with a control group of patients who received neck CTA studies for reasons other than ischemic stroke (n = 63).RESULTS:The prevalence of carotid webs in the cryptogenic stroke population was 21.2% (95% CI, 8.9%–38.9%). Patients with symptomatic carotid webs had a mean age of 38.9 years (range, 30–48 years) and were mostly African American (86%) and women (86%). In contrast, only 1.6% (95% CI, 0%–8.5%) of patients in the control group demonstrated a web. Our findings demonstrate a statistically significant association between carotid webs and ischemic stroke (OR = 16.7; 95% CI, 2.78–320.3; P = .01).CONCLUSIONS:Carotid webs exhibit a strong association with ischemic stroke, and their presence should be suspected in patients lacking other risk factors, particularly African American women.

Carotid artery webs are shelf-like intraluminal protrusions in the carotid bulb with emerging implications related to recurrent ischemic stroke.^1,2 Most carotid web cases have been previously described with conventional angiography.^3,4 More recently, the imaging characteristics on CTA have also been established. The typical appearance of a carotid web on CTA is a focal, gracile intraluminal filling defect along the posterior wall of the carotid bulb.^1,5 Superimposed thrombus has also been described, which is thought to be related to sluggish/turbulent blood flow produced by the filling defect.⁵Carotid webs also have been referred to as an atypical variant of fibromuscular dysplasia, with intimal fibrosis and hyperplasia on histology in contrast to the classic, medial variant.^3,6 Typical fibromuscular dysplasia occurs in middle-aged white women, with a classic “string of beads” imaging appearance, and does not have a direct association with ischemic stroke.^6,7Although considered a rare entity, a significant proportion of reported carotid web cases have been associated with recurrent ischemic strokes, most frequently in younger adults who lack other known risk factors.¹ Recent studies have revealed a mean age between 45 and 50 years in patients with carotid webs and associated ipsilateral carotid territory ischemic strokes, occurring more frequently in women than men.^1,5,8 There is limited reporting on the prevalence of carotid webs in the stroke population. A recent report on an Afro-Caribbean population demonstrated a 23% prevalence of carotid webs in young patients with ischemic stroke and a 7% prevalence among control patients.⁸ Up to one-third of all patients presenting with ischemic strokes lack an identifiable cause and are classified as “cryptogenic” in etiology, with most of these cases occurring in younger patients.⁹ Webs may be an under-recognized entity because of their subtle morphology and a lack of familiarity amongst radiologists and clinicians with this lesion. They could account for a significant portion of cryptogenic strokes, particularly in young adults.The purpose of our study was to determine the prevalence of carotid webs in a group of patients previously classified as having cryptogenic stroke.     

Selective-versus-Standard Poststent Dilation for Carotid Artery Disease: A Systematic Review and Meta-Analysis

BACKROUND:The safety and efficacy of standard poststent angioplasty in patients undergoing carotid artery stent placement have not been well-established.PURPOSE:We conducted a systematic review of the literature to evaluate the safety and efficacy of carotid artery stent placement and analyzed outcomes of standard-versus-selective poststent angioplasty.DATA SOURCES:A systematic search of MEDLINE, EMBASE, Scopus, and the Web of Science was performed for studies published between January 2000 and January 2015.STUDY SELECTION:We included studies with >30 patients describing standard or selective poststent angioplasty during carotid artery stent placement.DATA ANALYSIS:A random-effects meta-analysis was used to pool the following outcomes: periprocedural stroke/TIA, procedure-related neurologic/cardiovascular morbidity/mortality, bradycardia/hypotension, long-term stroke at last follow-up, long-term primary patency, and technical success.DATA SYNTHESIS:We included 87 studies with 19,684 patients with 20,378 carotid artery stenoses. There was no difference in clinical (P = .49) or angiographic outcomes (P = .93) in carotid artery stent placement treatment with selective or standard poststent balloon angioplasty. Both selective and standard poststent angioplasty groups had a very high technical success of >98% and a low procedure-related mortality of 0.9%. There were no significant differences between both groups in the incidence of restenosis (P = .93) or procedure-related complications (P = .37).LIMITATIONS:No comparison to a patient group without poststent dilation could be performed.CONCLUSIONS:Our meta-analysis demonstrated no significant difference in angiographic and clinical outcomes among series that performed standard poststent angioplasty and those that performed poststent angioplasty in only select patients.

Endovascular therapy of carotid artery disease has advanced during the past decade and is now considered a valuable treatment alternative to surgery in appropriately selected patients.^1–5 The indications for carotid endarterectomy were initially established in the North American Symptomatic Carotid Endarterectomy Trial⁶ in 1991, which expanded treatment indications to patients with symptomatic severe or moderate carotid stenoses. Formerly, patients who were not eligible for surgery were treated with percutaneous transluminal balloon angioplasty,^7,8 first described by Kerber et al in 1980.⁹ Although procedure-related complication rates were similar/comparable for both treatment modalities,^7,8,10 some potential drawbacks and specific problems occurred due to the endovascular approach, including luminal compromise from catheters and guidewires crossing the stenotic lesions and/or during balloon inflation (temporary carotid occlusion by a balloon and/or wire catheter), intraprocedural thromboembolic events, elastic vessel recoil, or intimal dissection.¹¹ After the carotid artery stent placement technique was developed, stent-assisted balloon angioplasty showed better results in event-free survival and even lower repeat angioplasty rates.¹¹ The primarily used balloon-expandable stents were increasingly replaced by self-expanding stents,^11,12 exhibiting an intrinsic radial expansion force with memory on the stenotic vessel wall. Poststent balloon angioplasty may then be performed to closely appose the stent and intima and, moreover, to expand regions of residual stent narrowing.¹¹Supporters of standard poststent balloon angioplasty (per protocol) indicated that poststent ballooning decreased the incidence of restenosis by re-establishing the normal luminal diameter. However, numerous studies^13–15 have suggested that poststent balloon dilation increases the likelihood of postprocedural emboli. Moreover, poststent ballooning can increase the probability of reflex bradycardia and hypotension, which might be associated with higher rates of periprocedural and postprocedural complications.^16–19Some authors claim that poststent dilation should be performed on a selective, case-by-case basis to maximize patient benefits and limit complications. However, to the best of our knowledge, there is no evidence in the recently published literature supporting the superiority of either of these techniques. Standard poststent balloon angioplasty has become the standard of care in many vascular centers,^20–35 and only some interventionalists^19,36–41 prefer performing poststent angioplasty on a selective base. On the basis of the latter studies, standard poststent balloon angioplasty may be associated with additional risks in patients with acceptable angiographic results, without additional post–carotid artery stent placement (CAS) angioplasty.To evaluate the safety and efficacy of standard poststent angioplasty versus selective poststent angioplasty, we conducted a systematic review and meta-analysis and analyzed outcomes by a series that performed standard poststent balloon angioplasty per protocol on all patients versus those that performed selective poststent balloon angioplasty on only a subset of patients.     

Patient-specific computational hemodynamics of intracranial aneurysms from 3D rotational angiography and CT angiography: an in vivo reproducibility study

BACKGROUND AND PURPOSE:Patient-specific simulations of the hemodynamics in intracranial aneurysms can be constructed by using image-based vascular models and CFD techniques. This work evaluates the impact of the choice of imaging technique on these simulations.MATERIALS AND METHODS:Ten aneurysms, imaged with 3DRA and CTA, were analyzed to assess the reproducibility of geometric and hemodynamic variables across the 2 modalities.RESULTS:Compared with 3DRA models, we found that CTA models often had larger aneurysm necks (P = .05) and that most of the smallest vessels (between 0.7 and 1.0 mm in diameter) could not be reconstructed successfully with CTA. With respect to the values measured in the 3DRA models, the flow rate differed by 14.1 ± 2.8% (mean ± SE) just proximal to the aneurysm and 33.9 ± 7.6% at the aneurysm neck. The mean WSS on the aneurysm differed by 44.2 ± 6.0%. Even when normalized to the parent vessel WSS, a difference of 31.4 ± 9.9% remained, with the normalized WSS in most cases being larger in the CTA model (P = .04). Despite these substantial differences, excellent agreement (κ ≥ 0.9) was found for qualitative variables that describe the flow field, such as the structure of the flow pattern and the flow complexity.CONCLUSIONS:Although relatively large differences were found for all evaluated quantitative hemodynamic variables, the main flow characteristics were reproduced across imaging modalities.

Degradative biologic processes in the arterial wall that lead to growth and rupture of intracranial aneurysms¹ have been related to intra-aneurysmal hemodynamics.^2–4 CFD simulations have been used to gain insight into the patient-specific hemodynamics and could potentially assist rupture-risk assessment^5–9 and treatment planning.^10–16Vascular models can be constructed through segmentation of 3DRA and CTA images. Compared with CTA, 3DRA produces images with higher contrast, higher spatial resolution, and lower visibility of bone,^17–19 which lead to better segmentation results²⁰ and superior anatomic accuracy.^21–23 However, acquisition of 3DRA images involves the introduction of a catheter into the cerebral vasculature to locally inject contrast agent, making it more invasive than CTA, in which contrast is injected in a peripheral vein.^24,25 As a result of this trade-off, 3DRA is often used before and during treatment, whereas CTA is often used for diagnosis and follow-up studies.²⁶To the best of our knowledge, the reproducibility of hemodynamic simulations based on in vivo images from different modalities is yet unknown. Previous studies did show that among all input parameters of the modeling pipeline, the vascular geometry has the greatest impact on its output.^27,28 Because the choice of imaging technique may affect the vascular geometry, it could give rise to differences in hemodynamic predictions. To investigate this issue, we conducted a study comparing simulations with 3DRA- and CTA-based vascular models of 10 aneurysms.     

Comparison of CTA- and DSA-Based Collateral Flow Assessment in Patients with Anterior Circulation Stroke

BACKGROUND AND PURPOSE:Collateral flow is associated with clinical outcome after acute ischemic stroke and may serve as a parameter for patient selection for intra-arterial therapy. In clinical trials, DSA and CTA are 2 imaging modalities commonly used to assess collateral flow. We aimed to determine the agreement between collateral flow assessment on CTA and DSA and their respective associations with clinical outcome.MATERIALS AND METHODS:Patients randomized in MR CLEAN with middle cerebral artery occlusion and both baseline CTA images and complete DSA runs were included. Collateral flow on CTA and DSA was graded 0 (absent) to 3 (good). Quadratic weighted κ statistics determined agreement between both methods. The association of both modalities with mRS at 90 days was assessed. Also, association between the dichotomized collateral score and mRS 0–2 (functional independence) was ascertained.RESULTS:Of 45 patients with evaluable imaging data, collateral flow was graded on CTA as 0, 1, 2, 3 for 3, 10, 20, and 12 patients, respectively, and on DSA for 12, 17, 10, and 6 patients, respectively. The κ-value was 0.24 (95% CI, 0.16–0.32). The overall proportion of agreement was 24% (95% CI, 0.12–0.38). The adjusted odds ratio for favorable outcome on mRS was 2.27 and 1.29 for CTA and DSA, respectively. The relationship between the dichotomized collateral score and mRS 0–2 was significant for CTA (P = .01), but not for DSA (P = .77).CONCLUSIONS:Commonly applied collateral flow assessment on CTA and DSA showed large differences, indicating that these techniques are not interchangeable. CTA was significantly associated with mRS at 90 days, whereas DSA was not.

Recently, the effectiveness of intra-arterial therapy (IAT) in patients with acute ischemic stroke of the anterior circulation treated within 6 hours after symptom onset was established by multiple randomized controlled trials.^1–5 In the Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN), the largest of these trials, a substantial number of patients did not reach functional independence, despite high recanalization rates after IAT. Other trials showed higher recanalization rates, with better overall patient outcome. Contrary to MR CLEAN, these latter trials used neuroimaging for patient selection. In the Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times (ESCAPE) trial, a CTA collateral score (CS) was used for this purpose.³Collaterals are defined as a network of vascular channels that variably restore blood flow when the main supplying artery is blocked.⁶ A good collateral circulation is believed to be of major importance for sustaining the penumbra in patients with acute ischemic stroke, is considered predictive of final infarct volume, and is associated with improved clinical outcome after both intravenous thrombolysis and IAT.^7–16The criterion standard for the assessment of collateral flow is multivessel DSA.¹⁷ This generates images with high spatial and temporal resolution, which allows the evaluation of contrast flow into the ischemic region via collaterals.^18,19 However, in practice, multivessel DSA is considered impractical as a primary diagnostic procedure for acute ischemic stroke triage because speed of treatment is an important factor in these cases. In addition, the expected benefit is low relative to the resources needed. Single-vessel DSA is the pragmatic choice but has several drawbacks, including incomplete assessment of the MCA or anterior cerebral artery territory. Alternatively, CTA is currently used for assessment of collateral flow because of its 24/7 availability and short acquisition time.^8–10 Also, good interrater agreement for this technique has been reported.^10,20 Additionally, CTA has the advantage of allowing visualization of collateral flow from all vessels at once, both intra- and extracranial.⁹ A drawback of CTA, however, is the lack of temporal information. Multiphase CTA could solve this problem, but it is not yet widely available.The purpose of this substudy of MR CLEAN was to assess the agreement between CTA and DSA for grading of collateral flow in patients with acute ischemic stroke due to proximal anterior circulation occlusion, analogous to current practice. In addition, we investigated the association of CTA and DSA collateral grades with clinical outcome as measured on the mRS.     

Intraplaque Hemorrhage and the Plaque Surface in Carotid Atherosclerosis: The Plaque At RISK Study (PARISK)

BACKGROUND AND PURPOSE:An important characteristic of vulnerable plaque, intraplaque hemorrhage, may predict plaque rupture. Plaque rupture can be visible on noninvasive imaging as a disruption of the plaque surface. We investigated the association between intraplaque hemorrhage and disruption of the plaque surface.MATERIALS AND METHODS:We selected the first 100 patients of the Plaque At RISK study, an ongoing prospective noninvasive plaque imaging study in patients with mild-to-moderate atherosclerotic lesions in the carotid artery. In carotid artery plaques, disruption of the plaque surface (defined as ulcerated plaques and/or fissured fibrous cap) and intraplaque hemorrhage were assessed by using MDCTA and 3T MR imaging, respectively. We used a χ² test and multivariable logistic regression to assess the association between intraplaque hemorrhage and disrupted plaque surface.RESULTS:One hundred forty-nine carotid arteries in 78 patients could be used for the current analyses. Intraplaque hemorrhage and plaque ulcerations were more prevalent in symptomatic compared with contralateral vessels (hemorrhage, 38% versus 11%; P < .001; and ulcerations, 27% versus 7%; P = .001). Fissured fibrous cap was more prevalent in symptomatic compared with contralateral vessels (13% versus 4%; P = .06). After adjustment for age, sex, diabetes mellitus, and degree of stenosis, intraplaque hemorrhage was associated with disrupted plaque surface (OR, 3.13; 95% CI, 1.25–7.84) in all vessels.CONCLUSIONS:Intraplaque hemorrhage is associated with disruption of the plaque surface in patients with a carotid artery stenosis of <70%. Serial studies are needed to investigate whether intraplaque hemorrhage indeed increases the risk of plaque rupture and subsequent ischemic stroke during follow-up.

The need to identify patients with mild-to-moderate carotid artery stenosis and an increased stroke risk who might benefit from surgical treatment has shifted research interest from assessment of the degree of carotid stenosis to assessment of vulnerable plaque characteristics.¹ Vulnerable plaques are atherosclerotic plaques more prone to rupture and are associated with a higher risk for thromboembolism and ischemic stroke.^2,3 Intraplaque hemorrhage is an important characteristic of the vulnerable plaque.⁴ Prevalence of intraplaque hemorrhage has been shown to be higher in symptomatic than in asymptomatic lesions.⁵ Moreover, the presence of intraplaque hemorrhage in carotid artery disease is associated with an increased risk of cerebral ischemic events.^6–8The pathophysiologic mechanism leading to intraplaque hemorrhage is a topic of debate. However, a common viewpoint is that small leaky neovessels in the atherosclerotic plaques are a likely source of intraplaque hemorrhage.^5,9,10 The presence of intraplaque hemorrhage is thought to initiate several biologic processes like phagocytosis and local inflammation, leading to the release of proteolytic enzymes, deposition of free cholesterol and subsequently plaque growth, plaque destabilization, and possible plaque rupture.^5,9–12 Plaque rupture can be visible on imaging as a disruption of the atherosclerotic plaque surface (plaque ulceration and/or a fissured fibrous cap).^13,14 A previous study reported that plaque ulceration on CTA was useful for the prediction of intraplaque hemorrhage on MR imaging in a broad group of symptomatic patients referred for carotid artery imaging.¹⁵ Ulcerated plaques themselves are independently associated with an increased risk of ipsilateral ischemic events as well.^16,17The aim of the current study was to investigate the association between intraplaque hemorrhage, as assessed on MR imaging, and disruption of the plaque surface, assessed on MDCTA, in symptomatic patients with a carotid artery stenosis of <70%.     

Performance of semiautomatic assessment of carotid artery stenosis on CT angiography: clarification of differences with manual assessment

BACKGROUND AND PURPOSE:Semiautomated methods for ICA stenosis measurements have the potential to reduce interobserver variability and to speed up its analysis. In this study, we estimate the precision and accuracy of a semiautomated measurement for carotid artery stenosis degree and identify and explain differences compared with the manual method.MATERIALS AND METHODS:In this retrospective study involving 90 patients, 2 observers determined the stenosis degree twice, with both the semiautomated and the manual method. Intra- and interobserver correlations were calculated for both methods. The accuracy was estimated by comparing average semiautomated with manual measurements. The semiautomated stenosis calculations were performed using either the minimal or maximal intersection at the reference site. Individual cases with large differences in measurement were retrospectively inspected by 3 observers.RESULTS:Intra- (R = 0.93, 0.96) and interobserver (R = 0.98) correlations for the semiautomated method were excellent and exceeded the manual performance correlations (R = 0.87, 0.86). The semiautomated measurements correlated well with the manual measurements (R = 0.87), with high specificity of 96% and lower sensitivity of 63%. Large differences were caused by misinterpretations of the semiautomated method associated with calcified plaques, resulting in overestimations of the minimal diameter, underestimation of stenosis degree, and incorrect centerlines. The effect of using the minimal diameter at the reference position resulted in a small, but significant, underestimation of the stenosis degree by the semiautomated method.CONCLUSIONS:The semiautomated method showed an excellent reproducibility and good correlation with manual measurements with a high specificity and lower sensitivity for detecting a significant stenosis. Erroneous semiautomatic stenosis measurements were associated with the presence of calcium.

Atherosclerotic stenosis of the ICA may lead to neurologic symptoms and is an important risk factor for ischemic stroke. Large randomized trials determined that CEA is beneficial for recently symptomatic patients with a severe (70%–99%) stenosis.^1–3 In the trials with symptomatic patients, a higher degree of stenosis was associated with increased benefit from surgery. Therefore, precise assessment of the degree of stenosis is crucial for decisions on CEA. Currently, CTA is increasingly used to measure the degree of carotid artery stenosis.⁴Determining the degree of carotid stenosis on CTA, according to the NASCET method, is tedious and may lead to clinically important differences.^5,6 Reading CTA studies requires some familiarity with postprocessing techniques, such as MPR. Semiautomated methods have been developed and introduced in the market to overcome the drawbacks of these measurements.^7–11 The potential advantages of such a system, such as the acceleration of measurements and reduced interobserver variability, have been widely acknowledged; however, the diagnostic value has not been sufficiently determined. Several studies have shown excellent intra- and interobserver variability,^7–13 yet the diagnostic accuracy and the cause of deviations of semiautomatic measurements have received little attention.The aim of this study was to validate semiautomated carotid stenosis measurements by comparison with a standard manual method.^14–16     

Can Doppler Flow Parameters of Carotid Stenosis Predict the Occurrence of New Ischemic Brain Lesions Detected by Diffusion-Weighted MR Imaging after Filter-Protected Internal Carotid Artery Stenting?

BACKGROUND AND PURPOSE:Carotid angioplasty and stent placement are increasingly being used for the treatment of symptomatic and asymptomatic carotid artery disease. Carotid angioplasty and stent placement carry an inherent risk of distal cerebral embolization, precipitating new brain ischemic lesions and neurologic symptoms. Our purpose was to evaluate the frequency of new ischemic lesions found on diffusion-weighted imaging after protected carotid angioplasty and stent placement and to determine the association of new lesions with ICA Doppler flow parameters.MATERIALS AND METHODS:Fifty-two patients (mean age, 68 ± 11 years) with 50%–69% (n = 20, group 1) and ≥70% (n = 32, group 2) internal carotid artery stenosis underwent carotid angioplasty and stent placement with distal filter protection. DWI was performed before and 48 hours after carotid angioplasty and stent placement.RESULTS:Thirty-three (63.4%) patients showed new lesions. The average number of new postprocedural lesions was 3.4 per patient. Most of the postprocedural lesions were <5 mm (range, 3–23 mm), cortical and corticosubcortical, and clinically silent. Group 2 had a significantly higher number of new lesions compared with group 1 (P < .001). A significant relationship was found between ICA Doppler flow parameters and the appearance of new lesions.CONCLUSIONS:The appearance of new ischemic lesions was significantly related to the Doppler flow parameters, particularly peak systolic velocity.

Stroke is the most common life-threatening neurologic disorder and the most important single cause of disability.^1,2 Carotid artery stenosis, a major risk factor for stroke, and distal embolization, arising from degenerative breakdown or thrombotic occlusion of complex plaques, are important mechanisms of stroke in patients with atherosclerotic internal carotid artery stenosis.^3–6 Duplex sonography is currently the principal and, undoubtedly, the most accurate noninvasive and inexpensive diagnostic technique available for the evaluation of internal carotid artery stenosis. It provides information about the presence and severity of carotid stenosis, the velocity and characteristics of blood flow, and plaque morphology.^7–10Carotid angioplasty and stent placement for severe internal carotid artery stenosis have been introduced as a safe alternative to medical and/or surgical treatment in patients at high risk for surgical procedures.^11,12 However, there is still a major concern regarding its safety because of the risk of distal cerebral embolization during the procedure. Recent technical refinements, therefore, have led to the widespread use of carotid artery stenting (CAS) with cerebral-protection devices, markedly reducing thromboembolic complication rates.¹³ Diffusion-weighted MR imaging is a very sensitive and specific technique for diagnosing cerebral ischemia.^14,15 It has been used to detect structural damage of the brain due to cerebral embolism after cerebral angiography, neurointerventional procedures, and carotid endarterectomy.^16,17The purpose of our study was to assess, with DWI, the number, size, and location of new brain lesions after protected CAS and to evaluate the association of these new lesion deficits and Doppler flow parameters of ICA.     

Intervention versus Aggressive Medical Therapy for Cognition in Severe Asymptomatic Carotid Stenosis

BACKGROUND AND PURPOSE:Asymptomatic carotid stenosis of ≥70% increases the incidence of microembolism and/or chronic hypoperfusion, which may consequently impair neurocognition and brain connections. We sought controlled evidence for any cognitive benefit of aggressive medical therapy and combined carotid revascularization.MATERIALS AND METHODS:Patients with asymptomatic, unilateral, ≧70% stenosis of the extracranial ICA chose either aggressive medical therapy alone or in combination with carotid artery stent placement in this nonrandomized controlled study. They were examined with a battery of neuropsychological tests, structural MR imaging, DTI, and resting-state fMRI before and 3 months after treatment.RESULTS:Forty patients were included with 15 in the medical group and 25 in the stent-placement group. Among them, 13 and 21 in the respective groups completed neuroimaging follow-up. The baseline characteristics and the changes in cognitive performance during 3 months showed no differences between treatment groups. Nevertheless, compared with the medical group, the stent-placement group showed subjective dizziness alleviation (P = .045) and a small increase in fractional anisotropy at the splenium of the corpus callosum and the posterior periventricular white matter ipsilateral to carotid artery stent placement. Moreover, only the stent-placement group showed interval improvement in immediate memory and visuospatial performance, which was accompanied by an increase of functional connectivity at the insular cortex of the dorsal attention network and the medial prefrontal cortex of the default mode network.CONCLUSIONS:Both aggressive medical therapy alone and combined carotid revascularization in ≧70% asymptomatic carotid stenosis similarly preserved cognition during 3-month follow-up, though the latter had the potential for dizziness alleviation and cognitive and connectivity enhancement.

Interventional revascularization for ≥60% asymptomatic ICA stenosis has long been debated, given the decreasing annual risk of ipsilateral ischemic stroke in these patients from 2.3% to 0.5% with the development of contemporary optimal medical treatment.^1–4 However, some of these patients carry a higher risk of stroke than others despite optimal medical treatment. Patients with detectable embolic signals by transcranial Doppler have a high annual risk (7%) of stroke.⁵ Stenotic degree of ≥90%, poor collaterals, and echolucent plaque texture could also stratify patients into groups with varying high stroke risk to >4% annually.^6,7 Thus, interventional revascularization should be considered in such patients. Recently, long-term randomized trials, the Asymptomatic Carotid Trial⁸ and the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST)⁹ demonstrated that there was no difference in the rate of late ipsilateral stroke after carotid endarterectomy or carotid artery stent placement (CAS) in asymptomatic and symptomatic patients. Of asymptomatic patients, the 5-year cumulative rate of stroke-free survival was 93.1% in the CAS group and 94.7% in the carotid endarterectomy group.⁸Hence, asymptomatic carotid stenosis has been viewed from a changing perspective from stroke risk to cognitive susceptibility.^10,11 We previously demonstrated that patients with unilateral asymptomatic carotid stenosis of ≥70% had more dizziness/unsteadiness and poorer verbal memory, executive function, and visuospatial perception than the healthy controls, accompanied by extensive widespread disruption of long-range structural and functional connectivity.^12,13 The mechanisms are likely attributed to microemboli from unstable carotid plaques⁵ and/or chronic hypoperfusion.^14,15 Single-arm studies of carotid revascularization accomplished by either carotid endarterectomy or CAS reported the controversial results of cognitive enhancement in patients with asymptomatic carotid stenosis.^15–20 However, there is a lack of medical-controlled evidence reflecting contemporary medical improvement and risk-benefit balance of interventions for cognitive preservation. Here, we investigate the impact of aggressive medical treatment with or without combined carotid revascularization on neurocognitive and connectivity outcomes at 3 months after treatment in patients with ≧70% asymptomatic carotid stenosis.     

Comparison of Dynamic Contrast-Enhanced 3T MR and 64-Row Multidetector CT Angiography for the Localization of Spinal Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE:For the localization of spinal dural arteriovenous fistulas, it is not determined whether dynamic contrast-enhanced MRA is more reliable than multidetector CTA. The aim of this study was to compare the agreement between intra-arterial DSA, dynamic contrast-enhanced MRA at 3T, and 64-row multidetector CTA for the localization of spinal dural arteriovenous fistulas.MATERIALS AND METHODS:We enrolled 12 consecutive patients (11 men, 1 woman; age range, 46–83 years; mean, 65 years) who underwent preoperative dynamic contrast-enhanced MRA at 3T and 64-row multidetector CTA. The spinal dural arteriovenous fistula location was confirmed by intra-arterial DSA as the reference standard. Two reviewers independently evaluated the level of the artery feeding the spinal dural arteriovenous fistula on the basis of continuity between the feeder and abnormal spinal vessels on 3T dynamic contrast-enhanced MRA and 64-row multidetector CTA images. Interobserver and intermodality agreement was determined by calculation of the κ coefficient.RESULTS:On DSA, the vessel feeding the spinal dural arteriovenous fistula was the intercostal artery (7 cases), the lumbar artery (3 cases), and the internal iliac artery or the ascending pharyngeal artery (1 case each). For the fistula level, interobserver agreement was excellent for 3T dynamic contrast-enhanced MRA (κ = 0.97; 95% CI, 0.92–1.00) and very good for 64-row multidetector CTA (κ = 0.84; 95% CI, 0.72–0.96). Intermodality agreement with DSA was good for 3T dynamic contrast-enhanced MRA (κ = 0.78; 95% CI, 0.49–1.00) and moderate for 64-row multidetector CTA (κ = 0.41; 95% CI, 0.020–0.84).CONCLUSIONS:For the localization of spinal dural arteriovenous fistulas, 3T dynamic contrast-enhanced MRA may be more reliable than 64-row multidetector CTA.

Spinal dural arteriovenous fistulas (SDAVF) are the most commonly encountered spinal vascular shunt lesions and a treatable cause of myelopathy.¹ The arteriovenous shunt is located inside the dura mater close to the spinal nerve root, where the arterial blood from a radiculomeningeal artery enters a radicular vein. Shunt interruption by either neurosurgery or superselective embolization is the basic treatment strategy,^1–3 and pretreatment localization of SDAVF is important for their adequate treatment. Catheter spinal DSA is the standard technique that accurately detects the location of SDAVF and their feeders. However, an exhaustive search for the lesion by selective catheterization is time-consuming and increases the amount of radiation exposure and contrast material and is accompanied by risks for neurologic complications.^4,5Noninvasive imaging modalities such as multidetector CTA and dynamic contrast-enhanced (DCE)-MRA reliably detect SDAVF and may predict the level of their location.^5–11 However, the noninvasive technique more reliable for the localization of SDAVF remains to be identified, and interobserver and intermodality agreement for the location of SDAVF on CTA and DCE-MRA studies has not been fully investigated.In multidetector CTA, scanner performance can be improved by adding detector rows,¹² and, in DCE-MRA, higher magnetic fields improve the image quality while reducing the acquisition time.¹³ In the present study, we compared the agreement between DSA, DCE-MRA at 3T, and 64-row multidetector CTA (64-CTA) for the localization of SDAVF.     

Diagnostic Impact of Bone-Subtraction CT Angiography for Patients with Acute Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE:Detection and evaluation of ruptured aneurysms is critical for choosing an appropriate endovascular or neurosurgical intervention. Our aim was to assess whether bone-subtraction CTA is capable of guiding treatment for cerebral aneurysms in patients with acute SAH and could replace DSA.MATERIALS AND METHODS:We prospectively studied 116 consecutive patients with SAH with 16–detector row bone-subtraction CTA and DSA before intracranial aneurysm treatment. Two independent neuroradiologists reviewed the bone-subtraction CTA blinded to DSA (reference standard). We determined the accuracy of bone-subtraction CTA for aneurysm detection and the measurement of aneurysm dimensions and compared the radiation doses of the 2 imaging modalities.RESULTS:Seventy-one patients (61%) had 74 aneurysms on DSA. Bone-subtraction CTA detected 73 of these aneurysms, but it detected 1 additional aneurysm. On a per-aneurysm basis, sensitivity, specificity, and positive and negative predictive values for bone-subtraction CTA were 99%, 98%, and 99% and 98%, respectively. For aneurysms of ≤3 mm, sensitivity was 94% (95% CI, 73%–99%). Bone-subtraction CTA slightly overestimated neck and dome diameters by <0.2 mm and overestimated the dome-to-neck ratios by 2% on average. Dose-length product was 565 ± 201 mGy × cm for bone-subtraction CTA and 1609 ± 1300 mGy × cm for DSA.CONCLUSIONS:Bone-subtraction CTA is as accurate as DSA in detecting cerebral aneurysms after SAH, provides similar information about aneurysm configuration and measures, and reduces the average effective radiation dose for vascular diagnostics by 65%. Diagnostic equivalence in association with dose reduction suggests replacing DSA with bone-subtraction CTA in the diagnostic work-up of spontaneous SAH.

Prompt detection and evaluation of ruptured intracranial aneurysms is critical for choosing an appropriate endovascular or neurosurgical intervention.¹ Invasive digital subtraction angiography carries an overall risk of neurologic complications, resulting in permanent deficits in 0.5%.^2,3 Providing false-negative results in 5%–10% of patients,⁴ it also may increase the risk of rebleeding.^5,6Multidetector CT angiography with high spatial resolution and bone-subtraction CTA (BSCTA) approaches the diagnostic accuracy of DSA in the detection of intracranial aneurysms.^7–12 Thus, BSCTA can be considered an alternative to DSA in treatment planning.^13,14 Some authors already recommend BSCTA as the primary imaging in acute SAH.^7,15,16 However, it still seems unclear whether BSCTA can provide sufficient information for therapy decisions, making diagnostic DSA redundant.^17,18We therefore tested the hypothesis that BSCTA is as accurate as DSA for the identification and characterization of cerebral aneurysms in patients with SAH, even for small aneurysms and for those at the level of the skull base. We additionally studied the reliability of BSCTA and radiation-exposure reduction by avoiding diagnostic DSA.     

Endovascular Management of Tandem Occlusion Stroke Related to Internal Carotid Artery Dissection Using a Distal to Proximal Approach: Insight from the RECOST Study

BACKGROUND AND PURPOSE:Internal carotid artery dissection is a common cause of stroke in young adults. It may be responsible for tandem occlusion defined by a cervical steno-occlusive carotid wall hematoma associated with an intracranial large-vessel stroke. Intravenous thrombolysis is associated with a poor clinical outcome in these cases, and endovascular treatment has not been specifically evaluated to date. Our aim was to evaluate endovascular treatment technical and clinical efficiency in this specific occlusion topography, in comparison with treatment of isolated anterior circulation stroke.MATERIALS AND METHODS:As part of our ongoing prospective stroke data base started in August 2009 (Prognostic Factors Related to Clinical Outcome Following Thrombectomy in Ischemic Stroke [RECOST] Study), we analyzed all carotid artery dissection tandem occlusion strokes and isolated anterior circulation occlusions. All patients were selected for endovascular treatment according to clinical-radiologic mismatch, NIHSS ≥ 7 and DWI-ASPECTS ≥5, within 6 hours after onset. For carotid artery dissection, the revascularization procedure consisted first of distal recanalization by a stent retriever in the intracranial vessel. Following assessment of the circle of Willis, internal carotid artery stent placement was only performed in case of insufficiency. Carotid artery dissection treatment efficacy, safety, and clinical outcome were compared with the results of the isolated anterior circulation occlusion cohort.RESULTS:Two hundred fifty-eight patients with an anterior circulation stroke were analyzed, including 57 with tandem occlusions (22%); among them, 20 were carotid artery dissection–related occlusions (7.6%). The median age of patients with tandem occlusions with internal carotid dissection was 52.45 versus 66.85 years for isolated anterior circulation occlusion (P < .05); the mean initial NIHSS score was 17.53 ± 4.11 versus 17.55 ± 4.8 (P = .983). The median DWI-ASPECTS was 6.05 versus 6.64 (P = .098), and the average time from onset to puncture was 4.38 for tandem occlusions versus 4.53 hours in isolated anterior circulation occlusion (P = .704). Complication rates and symptomatic intracranial hemorrhage were comparable in both groups (5% versus 3%, P = .49). The duration of the procedure was significantly prolonged in case of tandem occlusion (80.69 versus 65.45 minutes, P = .030). Fourteen patients with carotid artery dissection (70%) had a 3-month mRS of ≤ 2, without a significant difference from patients with an isolated anterior circulation occlusion (44%, P = .2). Only 5 carotid artery dissections (25%) necessitated cervical stent placement. No early ipsilateral stroke recurrence was recorded, despite the absence of stent placement in 15 patients (75%) with carotid artery dissection.CONCLUSIONS:Mechanical endovascular treatment of carotid artery dissection tandem occlusions is safe and effective compared with isolated anterior circulation occlusion stroke therapy. Hence, a more conservative approach with stent placement only in cases of circle of Willis insufficiency may be a reliable and safe strategy.

Internal carotid artery dissection (ICD) appears to be a common and increasingly diagnosed cause of ischemic stroke. It represents up to 20%–25% of stroke etiology in young adults¹ and is the most common cause in patients younger than 55 years of age. ICD is the consequence of a mural hematoma in the arterial wall, with separation of the intima from the media. The ischemic mechanism consists mainly of an internal carotid obstacle associated with intracranial clot migration, resulting in a so-called tandem occlusion.² Rarely, ICD may also be responsible for a hemodynamic stroke due to ICA lumen narrowing without intracranial occlusion in case of circle of Willis insufficiency. This last rare presentation was not addressed in the present study.ICD with tandem occlusion represents a stroke subtype associated with a poor prognosis.^3,4 Intravenous thrombolysis (IVT)⁵ is associated with poor recanalization rates and poor clinical outcomes.^1,3 Several published series have reported very low recanalization rates in tandem occlusions, from 8% to 9% during the first 2 hours^6,7 after thrombolytic drug infusion to 31% in the next 24–72 hours.⁴Endovascular treatment is now increasingly considered and performed, especially following the results from randomized controlled trials (Multicenter Randomized Clinical trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands [MR CLEAN], Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke [ESCAPE], Extending the Time for Thrombolysis in Emergency Neurological Deficits–Intra-Arterial [EXTEND-IA], Endovascular Revascularization With Solitaire Device Versus Best Medical Therapy in Anterior Circulation Stroke Within 8 Hours [REVASCAT], and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment [SWIFT PRIME]),^8–12 which demonstrated the superiority of combined strategies versus stand-alone intravenous treatments in large-vessel occlusion stroke. The particular, but not rare, tandem occlusion stroke subtype is still poorly explored. Despite promising results reported in the literature,^13–22 most of the larger trials available on thrombectomy previously cited^23–25 excluded ICD. As a result, to date there has been only limited evidence predominantly using a first-generation device for mechanical thrombectomy^26,27 and mixing tandem occlusion associated with ICD and ICA atheromatous stenosis. The aim of this study was to report the experience of our center in ICD tandem occlusion stroke and to compare the technical safety, efficacy, and 3-month clinical outcome in this subgroup with the results of our large-vessel anterior circulation stroke study (Prognostic Factors Related to Clinical Outcome Following Thrombectomy in Ischemic Stroke [RECOST]^28,29).     

Pial Artery Supply as an Anatomic Risk Factor for Ischemic Stroke in the Treatment of Intracranial Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE:Although intracranial dural arteriovenous fistulas are principally supplied by dural branches of the external carotid, internal carotid, and vertebral arteries, they can also be fed by pial arteries that supply the brain. We sought to determine the frequency of neurologic deficits following treatment of intracranial dural arteriovenous fistulas with and without pial artery supply.MATERIALS AND METHODS:One hundred twenty-two consecutive patients who underwent treatment for intracranial dural arteriovenous fistulas at our hospital from 2008 to 2015 were retrospectively reviewed. Patient data were examined for posttreatment neurologic deficits; patients with such deficits were evaluated for imaging evidence of cerebral infarction. Data were analyzed with multivariable logistic regression.RESULTS:Of 122 treated patients, 29 (23.8%) had dural arteriovenous fistulas with pial artery supply and 93 (76.2%) had dural arteriovenous fistulas without pial arterial supply. Of patients with pial artery supply, 4 (13.8%) had posttreatment neurologic deficits, compared with 2 patients (2.2%) without pial artery supply (P = .04). Imaging confirmed that 3 patients with pial artery supply (10.3%) had cerebral infarcts, compared with only 1 patient without pial artery supply (1.1%, P = .03). Increasing patient age was also positively associated with pial supply and treatment-related complications.CONCLUSIONS:Patients with dural arteriovenous fistulas supplied by the pial arteries were more likely to experience posttreatment complications, including ischemic strokes, than patients with no pial artery supply. The approach to dural arteriovenous fistula treatment should be made on a case-by-case basis so that the risk of complications can be minimized.

Intracranial dural arteriovenous fistulas (DAVFs) are vascular malformations that connect meningeal arteries to dural venous sinuses or cortical veins. DAVFs account for 10%–15% of all intracranial arteriovenous shunting lesions.^1–14 DAVFs are often thought to be acquired, sometimes in the setting of hypercoagulability.¹⁵ DAVF venous drainage determines the natural history risk of spontaneous intracranial hemorrhage. Thus, venous drainage is incorporated into the most commonly used grading systems of DAVF natural history risk: the Borden-Shucart and Cognard grading scales.^2,3 Drainage to cortical veins is the highest risk category because pressurization of these thin-walled venous structures frequently leads to rupture. Although venous angioarchitecture is a key determinant of natural history risk, the risk of endovascular and/or surgical treatment of DAVFs in the modern era related to underlying lesion angioarchitecture is not well-known.Although DAVFs are most commonly fed by dural branches of the internal carotid, external carotid, and vertebral arteries, they can also have pial artery supply. Pial arteries lie on the surface of the brain. They then branch into penetrating arteries and parenchymal arterioles that lie within and supply the brain parenchyma. The mechanism of pial feeder formation is not well-understood but is believed to be like that of dural feeders, with increased vascular endothelial growth factor secretion from the venous sinus and abnormal angiogenesis.^16–24 Embolization of pial AVFs has been suggested to lead to the development of subsequent DAVFs in up to 25% of cases.^25,26 The inflammatory reaction within the DAVF vessel wall after embolization may also lead to angiogenesis.²⁷Transarterial embolization of DAVFs with pial artery supply with agents that can migrate retrograde (ie, from the dural arteries to the pial arteries) could thus block blood supply to the associated brain parenchyma and cause ischemia. Surgical or endovascular point occlusion of DAVFs with pial artery supply at the fistula site might also result in retrograde thrombosis of feeding pial arteries due to decreased flow. We hypothesized that patients with DAVFs with pial artery supply have a higher risk of postoperative stroke than those who do not have pial supply.     

Parent Artery Curvature Influences Inflow Zone Location of Unruptured Sidewall Internal Carotid Artery Aneurysms

BACKGROUND AND PURPOSE:Future aneurysmal behaviors or treatment outcomes of cerebral aneurysms may be related to the hemodynamics around the inflow zone. Here we investigated the influence of parent artery curvature on the inflow zone location of unruptured sidewall internal carotid artery aneurysms.MATERIALS AND METHODS:In 32 aneurysms, the inflow zone location was decided by 4D flow MR imaging, and the radius of the parent artery curvature was measured in 2D on an en face image of the section plane corresponding to the aneurysm orifice.RESULTS:The inflow zone was on the distal neck in 10 (group 1, 31.3%), on the lateral side in 19 (group 2, 59.4%), and on the proximal neck in 3 (group 3, 9.4%) aneurysms. The radius in group 1 was significantly larger than that in group 2 (8.3 mm [4.5 mm] versus 4.5 mm [1.9 mm]; median [interquartile range]; P < .0001). All 7 aneurysms with a radius of >8.0 mm were in group 1. All 18 aneurysms with a radius of <6.0 mm were in group 2 or 3. In two group 3 aneurysms, the inflow zone was located in a part of the neck extending beyond the central axis of the parent artery.CONCLUSIONS:The inflow zone locations of sidewall aneurysms can be influenced by the parent artery curvature evaluated in 2D on an en face image of the section plane corresponding to the aneurysm orifice.

The hemodynamics around the inflow zone of cerebral aneurysms may be a principal cause of growth,^1–4 bleb formation resulting in rupture,^1,2,5–8 and regrowth following clipping surgery or endovascular coiling.^9–13 These sequelae are possibly related to the increased wall shear stress on the aneurysmal wall surrounding the inflow zone.^2–6,14 Therefore, both identification of the exact location of the inflow zone and evaluation of the hemodynamics around this area may contribute to predicting future aneurysmal behaviors or obtaining good treatment outcomes.¹⁵ Previous studies have estimated that neck width and geometric relationship between an aneurysm and the parent artery are dominant factors in the determination of the inflow zone location.^1,14,16–194D flow MR imaging based on time-resolved 3D cine phase-contrast MR imaging techniques was recently used to evaluate the hemodynamics of cerebral aneurysms^20–24 and to identify the inflow zone of cerebral aneurysms.¹⁵ However, no previous studies have examined the correlation between the distribution of the inflow zone on the section plane corresponding to the aneurysm orifice and aneurysm morphology or the parent artery curvature in patient-specific imaging analysis, to our knowledge. Here we investigated the influence of morphologic factors or the parent artery curvature on the inflow zone location identified by using 4D flow MR imaging in unruptured sidewall ICA aneurysms.     

Correlation between Fissured Fibrous Cap and Contrast Enhancement: Preliminary Results with the Use of CTA and Histologic Validation

BACKGROUND AND PURPOSE:Previous studies demonstrated that carotid plaques analyzed by CTA can show contrast plaque enhancement. The purpose of this preliminary work was to evaluate the possible association between the fissured fibrous cap and contrast plaque enhancement.MATERIALS AND METHODS:Forty-seven consecutive (men = 25; average age = 66.8 ± 9 years) symptomatic patients studied by use of a multidetector row CT scanner were prospectively analyzed. CTA was performed before and after contrast and radiation doses were recorded; analysis of contrast plaque enhancement was performed. Patients underwent carotid endarterectomy en bloc; histologic sections were prepared and evaluated for fissured fibrous cap and microvessel attenuation. The Mann-Whitney test was performed to evaluate the differences between the 2 groups. A multiple logistic regression analysis was performed to assess the effect of fissured fibrous cap and microvessel attenuation on contrast plaque enhancement. Receiver operating characteristic curve and area under the curve were also calculated.RESULTS:Twelve patients had fissured fibrous cap. In 92% (11/12) of fissured fibrous cap–positive plaques, we found contrast plaque enhancement, whereas in 69% (24/35) of the plaques without fissured fibrous cap contrast plaque enhancement was found. The Mann-Whitney test showed a statistically significant difference between the contrast enhancement in plaques with fissured fibrous cap (Hounsfield units = 22.6) and without fissured fibrous cap (Hounsfield units = 12.9) (P = .011). On the regression analysis, both fissured fibrous cap and neovascularization were associated with contrast plaque enhancement (P = .0366 and P = .0001). The receiver operating characteristic curve confirmed an association between fissured fibrous cap and contrast plaque enhancement with an area under the curve of 0.749 (P = .005).CONCLUSIONS:The presence of fissured fibrous cap is associated with contrast plaque enhancement. Histologic analysis showed that the presence of fissured fibrous cap is associated with a larger contrast plaque enhancement compared with the contrast plaque enhancement of plaques without fissured fibrous cap.

The presence of fissured fibrous cap (FFC) in the carotid artery plaque is associated with an increased risk of cerebrovascular events, and therefore FFC is considered one element that makes a carotid plaque “vulnerable.”^1–3 Identification of this condition is important to obtain a better stratification of stroke risk.¹The FFC has been studied by use of MR imaging, demonstrating the potential of MR imaging to detect the rupture of the fibrous cap,^4,5 with or without the use of gadolinium.^6,7 Recently, with the use of CTA and morphologic analysis of the carotid plaque, the FFC was documented.⁸ Even though the rupture of FFC has been shown to be associated with enhancement on MR imaging,⁷ this association has not yet been demonstrated by use of CT. The carotid plaque enhancement (CPE) on CTA is associated with plaque instability^9–11; CPE is associated with microvessel attenuation, but the neovascularization alone cannot be the only factor because some plaques with high CPE do not show neovascularization.⁹Our hypothesis is that the rupture of the FFC is an independent factor related to the CPE, and we aim to evaluate this association.