4D CTA结合CTP评价脑缺血后侧枝血流对脑灌注状态的影响

目的探讨4D CTA结合全脑容积CTP成像评价脑缺血后侧枝血流对脑灌注状态及预后的意义。方法 34位缺血性脑血管病患者(男24例,女10例,年龄42～84岁,平均年龄68.22岁),接受了全脑动态CTA-CTP成像,22例患者在初次检查后20～40天进行了影像学随诊。动态CTA-CTP结果与随访的影像结果进行比较。结果 34例患者中动态CTA-CTP成像阴性者3例,阳性者31例,诊断的敏感性96.88%,特异性100%。阳性者中29例为缺血性脑卒中患者,4 D CTA发现责任血管闭塞或狭窄23例,其中12例患侧可见侧枝血管形成,这12例患者预后良好。结论 4 D CTA技术是评价侧枝循环及脑灌注状态的可靠的和有效的方法,有助于临床制定个性化的治疗方案。     

MRI for the diagnosis of pulmonary embolism

Pulmonary embolism (PE) is one of the most frequently encountered clinical emergencies. The diagnosis often involves multiple diagnostic tests, which need to be carried out rapidly to assist in the safe management of the patient. Recent strides in computed tomography (CT) have made big improvements in patient management and efficiency of diagnostic imaging. This review article describes the developments in magnetic resonance (MR) techniques for the diagnosis of acute PE. Techniques include MR angiography (MRA) and thrombus imaging for direct clot visualization, perfusion MR, and combined perfusion-ventilation MR. As will be demonstrated, some of these techniques are now entering the clinical arena, and it is anticipated that MR imaging (MRI) will have an increasing role in the initial diagnosis and follow-up of patients with acute PE.     

单期和多期CT血管造影评估缺血性脑卒中患者侧支状态与CT灌注参数的对比性研究

目的 对于急性缺血性脑卒中(AIS)大脑中动脉闭塞患者,比较单时相、多时相CT血管造影(sCTA、mC-TA)评估的侧支循环评分与定量灌注参数之间的关联性及在预测临床预后中的价值.方法 搜集2019年12月至2020年12月于急救中心行一站式CT检查的发病时间在24 h内的大脑中动脉闭塞患者的临床资料及影像学资料,从C...     

Papel del estudio radiológico multimodal en el código ictus

In stroke code patients, multimodal imaging workup encompasses various imaging techniques, including baseline computed tomography (CT), magnetic resonance (MR) imaging, diffusion MR imaging, CT or MR perfusion studies, and CT or MR angiography, that are used to rule out bleeding, confirm arterial occlusion, establish tissue viability, and help select candidates for endovascular treatment as early as possible. Five recently published relevant clinical trials have demonstrated the efficacy of mechanical thrombectomy in proximal arterial occlusions; all these trials used different imaging techniques to select patients. Analyzing these trials and the scientific literature, we conclude that conventional CT interpreted with the Alberta Stroke Programme Computed Tomography Score (ASPECTS) and CT or MR angiography should always be used (level of evidence I, grade of recommendation A) and that CT and MR perfusion studies are useful in specific circumstances.     

Potential Influence of Acute CT on Inpatient Costs in Patients with Ischemic Stroke

RATIONALE AND OBJECTIVES: Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. MATERIALS AND METHODS: By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. RESULTS: The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. CONCLUSION: The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.     

Non-invasive assessment of bleeding pulmonary artery aneurysms due to Behçet disease

Because of its ability to depict intravascular, intramural, and extramural pathology, non-invasive imaging is well suited to assessing life-threatening hemoptysis that may complicate Beh?et disease. We made exclusive use of CT angiography supplemented by MR to identify pulmonary thromboembolism, mediastinal lymphadenopathy, and bilateral pulmonary artery aneurysms with signs of previous unilateral rupture. Two-dimensional reformatted CT images provided surgeons with a road map of upstream and downstream vascular relationships prior to aneurysm resection. Imaging findings were confirmed by surgery and pathology. Non-invasive imaging proved to be a useful alternative to standard catheter arteriography in the preoperative assessment of hemoptysis in this patient with Beh?et disease. Received 2 April 1997; Revision received 20 June 1997; Accepted 1 September 1997     

MR perfusion imaging using the arterial spin labeling technique for breast cancer

Purpose:

To investigate the feasibility of perfusion imaging using an arterial spin labeling (ASL) technique for breast cancer.

Materials and Methods:

Thirteen female patients with primary breast cancers were included in this study. All examinations were performed on 1.5 Tesla MRI systems. Visual evaluations of the colored perfusion map and MRI perfusion values were assessed. MRI and computed tomography (CT) perfusion values were compared.

Results:

Thirteen of 14 tumor lesions could be visualized on the colored perfusion map. CT perfusion examinations were performed in eight breasts, and the relationship between the blood flow values of CT perfusion and of MR perfusion showed a significant correlation.

Conclusion:

Nonenhanced MR imaging by an ASL technique is valid for depicting breast cancer, and the MR perfusion value is thought to be helpful for quantitative diagnosis of breast cancer. J. Magn. Reson. Imaging 2012;436‐440. © 2011 Wiley Periodicals, Inc.     

Combined MR proton lung perfusion/angiography and helium ventilation: potential for detecting pulmonary emboli and ventilation defects.

Three-dimensional (3D) perfusion imaging allows the assessment of pulmonary blood flow in parenchyma and main pulmonary arteries simultaneously. MRI using laser-polarized (3)He gas clearly shows the ventilation distribution with high signal-to-noise ratio (SNR). In this report, the feasibility of combined lung MR angiography, perfusion, and ventilation imaging is demonstrated in a porcine model. Ultrafast gradient-echo sequences have been used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast agent injections. 2D multiple-section (3)He imaging was performed subsequently by inhalation of 450 ml of hyperpolarized (3)He gas. The MR techniques were examined in a series of porcine models with externally delivered pulmonary emboli and/or airway occlusions. With emboli, perfusion deficits without ventilation defects were observed; airway occlusion resulted in matched deficits in perfusion and ventilation. High-resolution MR angiography can unambiguously reveal the location and size of the blood emboli. The combination of the three imaging methods may provide complementary information on abnormal lung anatomy and function.     

The emerging role of multidetector row CT angiography in the diagnosis of cervical arterial dissection: preliminary study

Introduction Cervical artery dissection is an important cause of ischemic stroke, particularly in young patients. The diagnosis can be made with invasive catheter angiography or non-invasive imaging, either with MRI in conjunction with MR angiography (MRA) or CT angiography (CTA). Both modalities have been shown to have a high specificity and sensitivity. New developments such as multi-slice CTA (MSCTA) are emerging as an alternative methods for imaging the cervical and intracranial arteries. However, the contribution of modern MSCTA to carotid artery dissection has not been reported.Methods We present a retrospective series of seven patients in whom both MSCTA and cervical axial T1 MRI and MRA were performed in the acute to subacute setting of internal carotid artery dissection.Results Carotid artery dissection was identified in all seven patients by MSCTA. The combination of MRI and MRA identified dissection in five of the seven patients. Additionally, a pseudoaneurysm was identified by MSCTA that was missed by MRI and MRA.Conclusion Our findings confirm that MSCTA is a complementary technique in comparison to cervical axial T1 MRI and cervical MRA for diagnosing carotid artery dissection, and at times may provide additional information that can impact patient management.     

CT和MR血管造影在颅内静脉畸形诊断中的应用

目的：评价CT、MR血管造影在诊断颅内静脉畸形中的价值与限度。材料和方法：5例经DSA证实的颅内静脉畸形病例,男2例,女3例,平均年龄37岁（10-66岁）,幕上1例,幕下4例。分别在动脉期（CTA）和静脉期（CTV）扫描采样,运用SSD和MIP进行重建,全部病例行MRA、MRV检查,4例做了增强前后MRV检查。结果：CTA显示所有病灶,但没有显示颅内静脉畸形的“海蛇头“,即引流静脉影像特征,而CTV不仅显示病灶,而且还显示了引流静脉“海蛇头“影像特征;MRV显示5例病灶和其特征性的“海蛇头“影像特征,MRA没有一例显示病灶的“海蛇头“表现,4例增强前后MRV没有明显差异。结论：MRV和静脉期的CT血管造影（CTV）是诊断和随访颅内静脉畸形的有效方法,优于动脉期的CT血管造影（CTA）,MRA可作筛选之用,排除其他血管性病变。     

Application of contrast agents in the evaluation of stroke: Conventional MR and echo-planar MR imaging

The availability of new therapeutic interventions, including neuroprotective agents and endovascular thrombolysis, has given new hope to patients suffering an acute stroke. Early intervention remains a key factor in the effectiveness of these new and traditional treatments. More importantly, the capability to assess the viability and reversibility of the ischemic tissue became essential for better delineation and differentiation of infarcted versus ischemic tissue and patient management. Abnormal MR imaging (MRI) findings during acute stroke usually reflect the underlying pathophysiologic changes, which can be classified into three sequential stages: (a) hypoperfusion, (b) cellular dysfunction and (c) breakdown of the blood-brain barrier. The first stage is a kinetic phenomenon (not biologic) and, therefore, can be detected immediately. Contrast agents accentuate the abnormal flow kinetics and facilitate the early diagnosis of ischemia using either conventional MRI or newly developed echo-planar perfusion imaging (EPPI). The demonstration of abnormal arterial or parenchymal enhancement on conventional MRI during acute stroke provides the earliest sign of vascular occlusion/stenosis. EPPI, in contrast, provides information related to microcirculation (< 100 microns) and tissue reserve (cerebral blood volume) that cannot be obtained by conventional angiography and is directly related to the target end-organ. Further information obtained from both contrast MRI and EPPI may have a predictive value in the clinical outcome of acute stroke patients.     

Perfusion CT and angio CT in the assessment of acute stroke

In order to evaluate the clinical utility of non-enhanced CT with perfusion and angio CT in the assessment of acute ischaemic stroke, 42 patients with symptoms of acute stroke were examined within the first 6 h from onset of symptoms with non-enhanced CT (NECT), perfusion CT (PCT) and CT angiography (CTA). Maps of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were analysed visually, and after drawing regions of interest (ROIs) in the territory of anterior, middle and posterior cerebral arteries, maximum-intensity projection and volume-rendering images of the cervical and cerebral vessels were created. All patients underwent a control CT or MR examination 24–48 h after the initial examination. Twenty-nine patients developed an area of infarction at control examinations. Significant perfusion abnormalities were found in 27 cases, whilst in two patients the perfusion studies were considered to be normal. All the cases with perfusion abnormalities showed arterial stenoses or occlusions on angio CT. Small infarctions at levels other than the ones selected for perfusion CT, and arteriosclerotic changes, were observed in the two cases with no perfusion abnormalities. In conclusion, combining non-enhanced CT with PCT and CTA is a simple and a very valuable tool in the initial assessment of acute stroke.     

Clinical MRI of acute ischemic stroke

The most important service that imaging provides to patients with ischemic stroke is to rapidly identify those patients who are most likely to benefit from immediate treatment. This group includes patients who have severe neurological symptoms due to an occlusion of a major artery, and who are candidates for recanalization using intravenous thrombolysis or intra-arterial intervention to remove the occlusion. Outcomes for these patients are determined by symptom severity, the artery that is occluded, the size of the infarct at the time of presentation, and the effect of treatment. MRI provides key physiological information through MR angiography and diffusion MRI that has been proven to be of high clinical value in identify patients who are in need of immediate treatment. Perfusion MRI provides information about the ischemic penumbra, but its clinical value is unproven. In current clinical practice, the time since stroke onset is dominant over physiologic information provided by MRI in treatment decisions. This will change only when clinical trials prove that stroke physiology as revealed by MRI is superior to time from stroke onset in promoting good clinical outcomes.     

Contribution of MRI and MR angiography in early diagnosis of brain death

The objective of this study was to investigate whether the findings of MR imaging and MR angiography could accurately and early diagnose brain death in comatose patients. Thirty comatose patients were studied with MRI and MR arteriography. In 20 patients (group A) presenting with a Glasgow coma scale (GCS) 3–6, the final clinical diagnosis was brain death. In ten comatose patients with a GCS 4–6 and no clinical signs of brain death (group B), the clinical follow-up did not reveal brain death in a period of 12 months. The MRI examination consisted of turbo fluid-attenuated inversion recovery and T2 turbo spin-echo pulse sequences. The MR arteriography was performed with a 3D inflow pulse sequence. In 12 patients with brain death and 5 patients with no signs of brain death, a 3D phase contrast MR venography was also applied. Magnetic resonance imaging in all patients showed variable edema with swelling of the cerebral gyri, small ventricular system, and basilar subarachnoid spaces. In group A, MRI in addition showed tonsillar herniation. In group A, MR arteriography revealed no arterial flow in the intracranial circulation, whereas MR venography showed in 9 patients no opacification of the sagittal and straight sinuses or visualization of intracranial veins. In contrast, MR angiography showed intact intracranial vessels in patients of group B. In conclusion, MR imaging and MR angiography may be reliable ancillary tests for use in early diagnosis of brain death and further work is required to validate its utility. Electronic Publication     

Magnetic resonance imaging of acute pulmonary embolism

Pulmonary embolism (PE) is a very common and potentially life-threatening disease. In comparison with CT, the clinical relevance of magnetic resonance imaging (MRI) for the assessment of PE is low. Nevertheless, as there are some potential advantages of MRI over CT (e.g. radiation free method, better safety profile of MR contrast media, capability of functional imaging). In certain patient, groups MRI might therefore be considered as a valuable alternative in the assessment of suspected PE. This article reviews the relevant MRI techniques for the evaluation of PE and gives an overview of the current literature for contrast-enhanced MR angiography of PE.     

ACR Appropriateness Criteria Clinically Suspected Pulmonary Arteriovenous Malformation

Pulmonary arteriovenous malformations are often included in the differential diagnosis of common clinical presentations, including hypoxemia, hemoptysis, brain abscesses, and paradoxical stroke, as well as affecting 30% to 50% of patients with hereditary hemorrhagic telangiectasia (HHT). Various imaging studies are used in the diagnostic and screening settings, which have been reviewed by the ACR Appropriateness Criteria Vascular Imaging Panel. Pulmonary arteriovenous malformation screening in patients with HHT is commonly performed with transthoracic echocardiographic bubble study, followed by CT for positive cases. Although transthoracic echocardiographic bubble studies and radionuclide perfusion detect right-to-left shunts, they do not provide all of the information needed for treatment planning and may remain positive after embolization. Pulmonary angiography is appropriate for preintervention planning but not as an initial test. MR angiography has a potential role in younger patients with HHT who may require lifelong surveillance, despite lower spatial resolution compared with CT.The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.     

Dynamic Angiography and Perfusion Imaging Using Flat Detector CT in the Angiography Suite: A Pilot Study in Patients with Acute Middle Cerebral Artery Occlusions

BACKGROUND AND PURPOSE:Perfusion and angiographic imaging using intravenous contrast application to evaluate stroke patients is now technically feasible by flat detector CT performed by the angiographic system. The aim of this pilot study was to show the feasibility and qualitative comparability of a novel flat detector CT dynamic perfusion and angiographic imaging protocol in comparison with a multimodal stroke MR imaging protocol.MATERIALS AND METHODS:In 12 patients with acute stroke, MR imaging and the novel flat detector CT protocol were performed before endovascular treatment. Perfusion parameter maps (MTT, TTP, CBV, CBF) and MIP/volume-rendering technique images obtained by using both modalities (MR imaging and flat detector CT) were compared.RESULTS:Comparison of MIP/volume-rendering technique images demonstrated equivalent visibility of the occlusion site. Qualitative comparison of perfusion parameter maps by using ASPECTS revealed high Pearson correlation coefficients for parameters CBF, MTT, and TTP (0.95–0.98), while for CBV, the coefficient was lower (0.49).CONCLUSIONS:We have shown the feasibility of a novel dynamic flat detector CT perfusion and angiographic protocol for the diagnosis and triage of patients with acute ischemic stroke. In a qualitative comparison, the parameter maps and MIP/volume-rendering technique images compared well with MR imaging. In our opinion, this flat detector CT application may substitute for multisection CT imaging in selected patients with acute stroke so that in the future, patients with acute stroke may be directly referred to the angiography suite, thereby avoiding transportation and saving time.

Flat detector CT (FD-CT) equipped angiographic systems are now widely used in neurointerventional institutions. Recently, an application to perform imaging of the brain parenchyma (FD-CT), cerebral vasculature (flat detector CT dynamic perfusion and angiographic imaging [FD-CTA]), and cerebral blood volume has been described and was evaluated in patients with acute middle cerebral artery occlusions.^1–3 However, this application was limited due to the inferior FD-CT soft-tissue resolution of the brain parenchyma in comparison with multisection CT (MS-CT) or MR imaging. Additionally, there was a lack of temporal resolution so that calculation of dynamic (time-dependent) perfusion parameters was not possible.Assessment of the impact of an ischemic stroke is best performed with physiologic criteria because especially in the acute phase, morphologic changes are only minimal and may be difficult to recognize by using MS-CT imaging.⁴ The use of perfusion and angiographic imaging increases the sensitivity of MS-CT and MR imaging in the acute phase of ischemic stroke. Thus, MS-CT angiography and MS-CT perfusion imaging are used to assess patients within a 0- to 4.5-hour time window of ischemic stroke. On the basis of the mismatch concept beyond 4.5 hours, multimodal MR imaging by using FLAIR, MR angiography, diffusion-weighted, and MR perfusion imaging (MRP) is used in many centers to identify patients eligible for recanalization therapies.⁵ MS-CT and MR imaging applications allow visualization of brain parenchyma and vessel occlusion (MS-CT angiography, MRA); and calculation of the dynamic perfusion parameter maps (time-to-peak, mean transit time, cerebral blood flow, and cerebral blood volume) to assess the viability of the brain.^6–9 The ability to obtain dynamic perfusion maps (FD-CTP) and angiographic images by using an intravenous contrast application within the angiography suite would seem to create a single ideal venue for both diagnosis and treatment of patients with an acute ischemic stroke. A FD-CT application replacing MS-CT or MR imaging would optimize the work flow, avoid transportation of the patient from one imaging location to the other, save time, and may allow periodic monitoring of brain viability during the endovascular treatment.To date, dynamic perfusion imaging with the C-arm angiographic system has been limited by the slow gantry rotation time. However, recent studies in canines and swine models have now demonstrated the feasibility of dynamic perfusion imaging with the use of a flat detector angiographic system.^10–12 The aim of this pilot study was to test the feasibility of this novel application by comparing FD-CTP and FD-CTA with a multimodal MR imaging protocol in patients with acute ischemic stroke. Additionally, the effective patient dose was evaluated.     

CT coronary angiography: Quantitative assessment of myocardial perfusion using test bolus data–initial experience

The aim of this study is to quantify myocardial perfusion during coronary CT angiography using data from a modified timing test-bolus acquisition. Institutional review board approval and informed consent were obtained. Nineteen patients with suspected coronary artery disease underwent combined coronary CT angiography and cardiac (82)Rubidium-PET perfusion. Prior to the CT angiogram a retrospectively ECG-gated dynamic test bolus was obtained following 25 mls of IV contrast medium injected at 5 ml/s. Images were acquired every 1.5 s for 30 s using 4 x 1.25-mm slices at 120 kV, 35 mAs. Regions of interest were drawn to delineate the myocardium and aorta on the resulting transaxial images. Time density curves were created and perfusion calculated using two simple approaches: maximum-slope method and peak method. In patients with normal PET myocardial perfusion, the mean (SD) resting myocardial perfusion estimated by CT using the maximum-slope method was 0.89 (+/-0.27) ml/min/g and 0.93 (+/-0.21) ml/min/g at end-systole and end-diastole, respectively, and 0.69 (+/-0.11) ml/min/g and 0.79 (+/-0.19) at end-systole and end-diastole, respectively, for the peak method. Thus quantification of myocardial perfusion from a routine coronary CT angiography test bolus is possible. CT-derived myocardial perfusion values are consistent with published values derived from other techniques.     

Evaluation of renal arteries in living renal donors: comparison between MDCT angiography and gadolinium-enhanced 3D MR angiography

Purpose The purpose of this study was to clarify and compare the accuracy of contrast-enhanced computed tomography (CT) angiography using multidetector-row helical CT (MDCT angiography) and gadolinium-enhanced MR angiography using three-dimensional Fourier transformation gradient-echo sequence (3D MR angiography) for preoperative evaluation of renal arteries in living renal donors. Materials and methods A total of 42 living renal donor candidates underwent both MDCT angiography and 3D MR angiography before digital subtraction angiography (DSA). Each MDCT angiogram and 3D MR angiogram was prospectively interpreted, and the findings were compared with the DSA results. Results MDCT angiography identified all of the 12 supernumerary arteries detected by DSA, whereas 3D MR angiography identified only 8. MDCT angiography identified all of the 19 proximal arterial branches detected by DSA, whereas 3D MR angiography identified only 16. Conclusion A more accurate depiction of renal arteries in living renal donors can be achieved with MDCT angiography than with 3D MR angiography.     

MR imaging of recent non-traumatic intracranial hemorrhage: early experience at 3 T

Magnetic resonance imaging (MRI) using 3.0 T scanners in the clinical environment is in its infancy and is only available at a limited number of sites worldwide. There is great interest amongst radiologists about the perceived benefits of clinical imaging at 3.0 T; however, it remains to be seen whether the theoretical advantages will bring real gains. MRI in patients with non-traumatic intracranial hemorrhage (ICH) is difficult, yet, these patients benefit from non-invasive angiography. Conventional catheter angiography (CCA) remains the reference standard for excluding/confirming the presence of intracranial vascular abnormalities, but MR angiography at 3.0 T may offer opportunities for significant changes in patient management. We present our experiences of using 3.0 T MR angiography in 27 patients with acute or early subacute ICH.