Quantitative hepatic CT perfusion measurement: Comparison of Couinaud's hepatic segments with dual-source 128-slice CT

Purpose

To compare the quantitative liver computed tomography perfusion (CTP) differences among eight hepatic segments.

Materials and methods

This retrospective study was based on 72 acquired upper abdomen CTP scans for detecting suspected pancreas tumor. Patients with primary or metastatic liver tumor, any focal liver lesions except simple cyst (<3 cm in diameter), history of liver operation or splenectomy, evidence of liver cirrhosis or invasion of portal vein were excluded. The final analysis included 50 patients (M:F = 21:29, mean age = 43.2 years, 15–76 years). Arterial liver perfusion (ALP), portal-venous perfusion (PVP), total hepatic perfusion (THP = ALP + PVP), and hepatic perfusion index (HPI) of each hepatic segment were calculated and compared by means of one-way analysis of variance (ANOVA) and the Bonferonni correction method.

Results

Compared to hepatic segments 5, 6, 7 and 8, segments 2 and 3 showed a tendency of higher ALPs, lower PVPs, and higher HPIs, most of which were statistically significant (p < 0.05). Hepatic segments 1 and 4 had higher mean values of ALP and HPI and lower mean values of PVP than segments 5, 6, 7 and 8 as well, although no significant differences were detected except for ALP and HPI for liver segments 1 and 7 (p = 0.001 and 0.035 respectively), and ALP for liver segments 1 and 5 (p = 0.039). Higher ALP and HPI were showed in hepatic segment 3 compared to segment 4 (p = 0.000 and 0.000 respectively). No significant differences were found for THP among eight segments.

Conclusions

Intra-hepatic perfusion differences exist in normal hepatic parenchyma especially between lateral sector (segments 2 and 3) and right lobe (segments 5, 6, 7 and 8). This might have potential clinical significance in liver-perfusion-related protocol design and result analysis.     

Apparent diffusion coefficient (ADC) in liver fibrosis: Usefulness of normalized ADC using the spleen as reference organ

Objective

The purpose of the current study was to determine the usefulness of the usage of the spleen as a reference organ to normalize liver ADC to improve the diagnostic performance of diffusion weighted imaging (DWI) for assessing liver fibrosis.

Materials and methods

Forty-nine subjects, 34 patients with liver disease and 15 control subjects were assessed with diffusion-weighted imaging. Liver ADC and normalized liver ADC (defined as the ratio of liver ADC to spleen ADC) were compared between patients and the control groups as well as among patients with different stages of fibrosis. Receiver operating characteristic (ROC) analysis was used to determine the performance of ADC and normalized liver ADC for prediction of liver fibrosis and cirrhosis.

Results

There was no significant difference between spleen ADC values among patients in comparison to control (1.107 ± 0.07 × 10⁻³mm²/s vs. 1.12 ± 0.068 × 10⁻³mm²/s, p = 0.998) or among patients with different stages of fibrosis (p = 0.59–0.89). The mean liver ADC and mean normalized liver ADC values were significantly lower in patients with hepatic fibrosis compared to volunteers (P = 0.01,<0.001 respectively), however liver ADC could not significantly differentiate different stages of fibrosis except between stages 0 and 4. The mean normalized liver ADC was significantly different between stage 0 and stages 2, 3, and 4 as well as between stage 1 and stage 4. In addition, it had a trend toward significance between stage 0 and 1, stage 2 and 4 as well as stage 3 and 4. Both liver ADC and normalized liver ADC had a significant negative correlation with the grade of fibrosis, however it was more powerful for normalized liver ADC in comparison to liver ADC (r = −0.694 vs. −0.361, p = 0.01 vs. 0.05). ROC analysis showed higher performance using normalized liver ADC in comparison to liver ADC, with higher AUC, sensitivity, and specificity for detection of fibrotic stages ?2 (0.88, 92.5% and 76.2% Vs 0.72, 82.1%, and 57.1% respectively). The corresponding values for stages ?3 were 0.83, 100%, and 55% vs. 0.69, 77.3%, and 44.4% respectively), while the corresponding values for cirrhosis (stage 4) were 0.87, 81.8%, and 81.8% for normalized liver ADC vs. 0.74, 69.2%, 72.2%.for ADC liver.

Conclusion

The utility of using the spleen as a reference organ could improve the diagnostic performance of ADC measurement for the diagnosis of liver fibrosis. The application of this technique for the evaluation of liver fibrosis is promising.     

CT of the abdomen: Degree and quality of enhancement obtained with two concentrations of the same iodinated contrast medium with fixed iodine delivery rate and total iodine load

Objectives

to compare vascular and parenchymal enhancement in abdominal computed tomography (CT) using two iodine concentrations (370 vs 300 mg I/mL) of the same contrast medium (CM) molecule (iopromide), using fixed iodine delivery rate (IDR, 1.2 g I/s) and total iodine load (630 mg I/kg).

Methods

144 patients were randomized into two groups: group A receiving iopromide 370 and group B receiving iopromide 300. Attenuation values (AV) were measured in correspondence to key anatomical structures on different phases and compared between groups with parametrical tests. Qualitative analysis was also performed. Peak injection pressure and local discomfort at the site of injection (pain and warmth) were registered.

Results

mean AV of abdominal aorta in late arterial phase were 300.32 ± 59.76 for group A and 298.2 ± 59.14 for group B (p = 0.8); mean AV of portal vein in portal phase were 190.5 ± 29.92 for group A and 192.91 ± 24.12 for group B (p = 0.6). Mean AV of liver parenchyma in portal phase were 124.73 ± 18.22 for group A and 125.11 ± 15.7 for group B (p = 0.9); mean AV of liver at equilibrium were 85.11 ± 7.75 for group A and 85.41 ± 8.09 for group B (p = 0.8). Qualitative analysis did not show significant differences between groups (p > 0.05). Median peak injection pressure was lower in group B (93 psi, 76–172) than in group A (115 psi, 88–288, p < 0.0001), while discomfort at injection site was not significantly different (p > 0.05).

Conclusions

with fixed IDR and total iodine load, comparable quantitative and qualitative enhancement can be achieved with different concentrations of the same CM. Peak injection pressure increases using CM with higher iodine concentration.     

Impact of liver cirrhosis on liver enhancement at Gd-EOB-DTPA enhanced MRI at 3 Tesla

Purpose

The purpose of this study was to assess differences in enhancement effects of liver parenchyma between normal and cirrhotic livers on dynamic, Gd-EOB-DTPA enhanced MRI at 3 T.

Materials and methods

93 patients with normal (n = 54) and cirrhotic liver (n = 39; Child–Pugh class A, n = 18; B, n = 16; C, n = 5) underwent contrast-enhanced MRI with liver specific contrast media at 3 T. T1-weighted volume interpolated breath hold examination (VIBE) sequences with fat suppression were acquired before contrast injection, in the arterial phase (AP), in the late arterial phase (LAP), in the portal venous phase (PVP), and in the hepatobiliary phase (HBP) after 20 min. The relative enhancement (RE) of the signal intensity of the liver parenchyma was calculated for all phases.

Results

Mean RE was significantly different among all evaluated groups in the hepatobiliary phase and with increasing severity of liver cirrhosis, a decreasing, but still significant reduction of RE could be shown. Phase depending changes of RE for each group were observed. In case of non-cirrhotic liver or Child–Pugh Score A cirrhosis mean RE showed a significant increase between AP, LAP, PVP and HBP. For Child–Pugh B + C cirrhosis RE increased until PVP, however, there was no change in case of B cirrhosis (p = 0.501) and significantly reduced in case of C cirrhosis (p = 0.043) during HBP.

Conclusion

RE of liver parenchyma is negatively affected by increased severity of liver cirrhosis, therefore diagnostic value of HBP could be limited in case of Child Pugh B + C cirrhosis.     

Evaluation of the relationship between renal function and renal volume-vascular indices using 3D power Doppler ultrasound

Purpose

To investigate the relationship between renal function and total renal volume-vascular indices using 3D power Doppler ultrasound (3DPDUS).

Materials and methods

One hundred six patients with hypertensive proteinuric nephropathy (HPN) (49 male, 57 female) and 65 healthy controls (32 male, 33 female) were evaluated prospectively using 3DPDUS. Total renal volume (RV), vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated using Virtual Organ Computer-aided Analysis (VOCAL). The estimated glomerular filtration rates (GFRs) of the patients with HPN and the control group were calculated. The patients with HPN were divided into two groups on the basis of GFR, normal (≥90) or reduced (<90). Differences between groups were compared using ANOVA. Correlations between GFR, renal volume and vascular indices were analyzed using Pearson's correlation analysis. Significance was set at p < 0.05.

Results

The mean total RV, VI, FI and VFI values in the reduced GFR, normal GFR and control groups were RV (ml): 234.7, 280.7 and 294.6; VI: 17.6, 27.6 and 46.8; FI: 79.1, 88.7 and 93.9 and VFI: 7.1, 12.7 and 23.8. There were statistically significant differences between the groups (p < 0.001). Total RVs and vascular indices exhibited significant correlations with estimated GFR (r = 0.53–0.59, p < 0.001)

Conclusion

Three-dimensional power Doppler ultrasound is a reliable predictive technique in renal function analysis.     

Renal masses measuring under 2 cm: Pathologic outcomes and associations with MRI features

Purpose

To evaluate pathologic outcomes and associations with MRI features in small renal masses measuring up to 20 mm

Methods

86 patients (61 ± 13 years; 45 M/41F) with 92 renal masses measuring up to 20 mm that underwent MRI prior to tissue diagnosis were included. Two radiologists independently evaluated all masses for microscopic lipid, hemorrhage, T2-hyperintensity, T2-homogeneity, cystic/necrotic areas, hypervascularity, enhancement homogeneity, circumscribed margins, and predominantly exophytic location. These MRI features, as well as patient age, gender, and history of RCC, were compared with pathologic findings using Fisher's exact test, unpaired t-test, and multivariate logistic regression.

Results

26.1% (24/92) of masses under 2 cm were benign, only 32.6% (30/92) were clear-cell RCC, and only 7.6% (7/92) were high-grade. Among 16 masses measuring up to 1 cm, only 12.5% (2/16) were clear-cell RCC, and none was high-grade. Within the entire cohort, no MRI or clinical feature showed a significant difference between benign and malignant lesions (p ≥ 0.053). However, for both readers, clear-cell RCC exhibited a significantly higher frequency of T2-hyperintensity, cystic/necrotic areas, and hypervascularity, and a significantly lower frequency of hemorrhage, T2-homogeneity, and enhancement homogeneity (p < 0.001–0.036). Hypervascularity was a significant independent predictor of clear-cell RCC for both readers (p = 0.002–0.007), as was T2-hyperintensity for reader 2 (p = 0.007).

Conclusion

A substantial fraction of small renal masses were benign, and when malignant, largely exhibited indolent pathologic characteristics, particularly when measuring under 1 cm Although small benign and malignant masses could not be differentiated on MRI, hypervascularity showed a significant independent association with clear-cell RCC in comparison with other lesions.     

Additional value of dual-energy CT to differentiate between benign and malignant mediastinal tumors: An initial experience

Objectives

To investigate the feasibility of dual-energy computed tomography (DECT) in differentiating malignant from benign mediastinal tumors.

Materials and methods

We prospectively enrolled 25 patients (14 males; mean age: 56.7 years) who had suspected mediastinal tumors on chest radiography or non-contrast chest computed tomography (CT). All patients underwent a two-phase DECT using gemstone spectral imaging (GSI) mode (GE HD750). For the quantitative analysis, two investigators measured the following parameters of the tumors in the early and the delayed phases: CT attenuation value in Hounsfield units (HU) and iodine concentration (mg/ml). Pathological results were used for a final diagnosis. Statistical analyses were performed using the Fisher's exact test and the Mann–Whitney t-test.

Results

10 patients (40%) had benign pathology, while 15 (60%) had malignant pathology. The iodine concentration measurements were significantly different between benign and malignant tumors both in the early phase (1.38 mg/ml vs. 2.41 mg/ml, p = 0.001) and in the delayed phase (1.52 mg/ml vs. 2.84 mg/ml, p = 0.001), while mean attenuation values were not significantly different in both phases (57.8 HU vs. 69.1 HU, p = 0.067 and 67.4 HU vs. 78.4 HU, p = 0.086, respectively).

Conclusions

Dual-energy CT using a quantitative analytic methodology can be used to differentiate between benign and malignant mediastinal tumors     

Dose and image quality of high-pitch dual source computed tomography for the evaluation of cervical lymph node status – Comparison to regular 128-slice single source computed tomography

Purpose

A high-pitch dual-source CT (DSCT) was compared to a standard single-source CT protocol in terms of dose and image quality for malignant lymphoma staging.

Materials and methods

Data from 43 patients who underwent DSCT (group 1) of the neck for staging of malignant lymphoma and 40 patients who underwent regular single source CT (group 2) were investigated retrospectively. Volume CT dose index (CTDIvol), dose length product (DLP), background noise (BN), attenuation values, signal-to-noise-ratio (SNR), scan time, effective tube current-time product (eff. mAs), subjective diagnostic image quality and artifact burden were compared.

Results

CTDIvol (5.5 ± 0.8 mGy vs. 12.4 ± 1.4 mGy), DLP (172 ± 27 mGycm vs. 344 ± 60 mGycm, p < 0.0001), eff. mAs (98 ± 15 mAs vs. 183 ± 20 mAs, p < 0.0001) and scan time (0.64 ± 0.05 s vs. 8.21 ± 0.72 s) were lower for group 1. BN was higher (p < 0.001) for group 1 with a mean difference of 2.6 HU. SNR for sternocleidomastoid and pectoral muscle was lower (6.6–12.3 vs. 7.8–19.1) for group 1. Subjective image quality (1.55 ± 0.6 vs. 1.42 ± 0.5) and artifact burden (1.62 ± 1.0 vs. 1.57 ± 0.9) were not rated significantly different (p = 0.47 and p = 0.80) with a good inter-observer agreement (κ = 0.59–0.90).

Conclusion

High-pitch DSCT allows reduction of patient dose for cervical lymphoma staging while diagnostic image quality is preserved.     

MRI evidence for preserved regulation of intracranial pressure in patients with cerebral arteriovenous malformations

Purpose

The purpose of this study was to investigate intracranial pressure and associated hemo- and hydrodynamic parameters in patients with cerebral arteriovenous malformations AVMs.

Methods

Thirty consecutive patients with arteriovenous malformations (median age 38.7 years, 27/30 previously treated with radiosurgery) and 30 age- and gender-matched healthy controls were investigated on a 3.0 T MR scanner. Nidus volume was quantified on dynamic MR angiography. Total arterial cerebral blood flow (tCBF), venous outflow as well as aqueductal and craniospinal stroke volumes were obtained using velocity-encoded cine-phase contrast MRI. Intracranial volume change during the cardiac cycle was calculated and intracranial pressure (ICP) was derived from systolic intracranial volume change (ICVC) and pulse pressure gradient.

Results

TCBF was significantly higher in AVM patients as compared to healthy controls (median 799 vs. 692 mL/min, p = 0.007). There was a trend for venous flow to be increased in both the ipsilateral internal jugular vein (IJV, 282 vs. 225 mL/min, p = 0.16), and in the contralateral IJV (322 vs. 285 mL/min, p = 0.09), but not in secondary veins. There was no significant difference in median ICP between AVM patients and control subjects (6.9 vs. 8.6 mmHg, p = 0.30) and ICP did not correlate with nidus volume in AVM patients (ρ = −0.06, p = 0.74). There was a significant positive correlation between tCBF and craniospinal CSF stroke volume (ρ = 0.69, p = 0.02).

Conclusions

The elevated cerebral blood flow in patients with AVMs is drained through an increased flow in IJVs but not secondary veins. ICP is maintained within ranges of normal and does not correlate with nidus volume.     

Dual-energy CT to detect recurrent HCC after TACE: Initial experience of color-coded iodine CT imaging

Objectives

To evaluate the feasibility of diagnosing recurrence of HCC after TACE color-coded iodine CT (CICT) based on arterial phase scans obtained by a dual-energy CT (DECT) scanner.

Methods

A CICT scan was acquired from an iodine map after applying material decomposition of the liver tissue and setting a threshold attenuation level for viable tumors. Two radiologists reviewed both conventional and CICT sets in 31 patients who had a history of TACE for HCC. The performances in detecting local tumor progression (LTP) were evaluated by alternative free-response receiver operating characteristics. The rate of uncertain diagnosis and interobserver agreement of the diagnosis were explored. Additionally, the reading time and radiation dose were also investigated.

Results

The mean figures of merit of the conventional and CICT sets for LTP were 0.818 and 0.847, respectively (p = 0.459). The rate of uncertain diagnosis was significantly decreased in CICT sets (34.5% vs. 0%), and interobserver agreement was improved (k = 0.527 vs. 0.718). On the CICT set, mean reading time was reduced by 49 s and mean radiation dose was also decreased by 18.3% when replacing the non-contrast CT with CICT.

Conclusions

CICT is comparable to conventional liver CT protocol in demonstrating viable HCCs, while it allows a reduction in radiation dose.     

Impact of thrombocytopenia on radiofrequency ablation therapy of hepatocellular carcinoma in patients with liver cirrhosis

Objective

The objective of our study was to assess the impact of thrombocytopenia on percutaneous radiofrequency ablation (RFA) therapy of Hepatocellular carcinoma (HCC) in patients with liver cirrhosis.

Material and methods

We analyzed retrospectively 64 patients with liver cirrhosis and thrombocytopenia, defined as a platelet count of less than 100 × 10³/mm³ that had undergone percutaneous RFA to treat 86 HCCs. The Kaplan–Meier and Cox regression methods were used to predict hemorrhage, and time to the first decompensation event, defined as the development of ascites, hepatic encephalopathy, variceal hemorrhage, and deterioration of liver function to Child-Pugh class B/C.

Results

There were no significant risk factors of hemorrhage. Univariate and multivariate analyses revealed that liver decompensation was clearly linked to prothrombin activity (p = 0.010 and p = 0.006, respectively) and a ? 63% of prothrombin activity was found as significant threshold for the occurrence of liver decompensation (p = 0.003) confirmed by the Cox model (p = 0.05).

Conclusion

Percutaneous RFA for HCC can be performed safely without the need for support, in patients with liver cirrhosis and thrombocytopenia up to 37 × 10³/mm³.     

Which are the cut-off values of 2D-Shear Wave Elastography (2D-SWE) liver stiffness measurements predicting different stages of liver fibrosis,considering Transient Elastography (TE) as the reference method?

Introduction

To identify liver stiffness (LS) cut-off values assessed by means of 2D-Shear Wave Elastography (2D-SWE) for predicting different stages of liver fibrosis, considering Transient Elastography (TE) as the reference method.

Methods

Our prospective study included 383 consecutive subjects, with or without hepatopathies, in which LS was evaluated by means of TE and 2D-SWE. To discriminate between various stages of fibrosis by TE we used the following LS cut-offs (kPa): F1-6, F2-7.2, F3-9.6 and F4-14.5.

Results

The rate of reliable LS measurements was similar for TE and 2D-SWE: 73.9% vs. 79.9%, p = 0.06. Older age and higher BMI were associated for both TE and 2D-SWE with the impossibility to obtain reliable LS measurements. Reliable LS measurements by both elastographic methods were obtained in 65.2% of patients. A significant correlation was found between TE and 2D-SWE measurements (r = 0.68). The best LS cut-off values assessed by 2D-SWE for predicting different stages of liver fibrosis were: F ≥ 1: >7.1 kPa (AUROC = 0.825); F ≥ 2: >7.8 kPa (AUROC = 0.859); F ≥ 3: >8 kPa (AUROC = 0.897) and for F = 4: >11.5 kPa (AUROC = 0.914).

Conclusions

2D-SWE is a reliable method for the non-invasive evaluation of liver fibrosis, considering TE as the reference method. The accuracy of 2D-SWE measurements increased with the severity of liver fibrosis.     

Factors associated with the impossibility to obtain reliable liver stiffness measurements by means of Acoustic Radiation Force Impulse (ARFI) elastography—Analysis of a cohort of 1031 subjects

Introduction

Acoustic Radiation Force Impulse (ARFI) elastography is a non-invasive technique for liver fibrosis assessment.

Aim

To assess the feasibility of ARFI elastography in a large cohort of subjects and to identify factors associated with impossibility to obtain reliable liver stiffness (LS) measurements by means of this technique.

Methods

Our retrospective study included 1031 adult subjects with or without chronic liver disease. In each subject LS was assessed by means of ARFI elastography. Failure of ARFI measurements was defined if no valid measurement was obtained after at least 10 shots and unreliable in the following situations: fewer than 10 valid shots; or median value of 10 valid measurements with a success rate (SR) < 60% and/or an interquartile range interval (IQR) ≥ 30%.

Results

Failure of LS measurements by means of ARFI was observed in 4 subjects (0.3%), unreliable measurements in 66 subjects (6.4%), so reliable measurements were obtained in 961 subjects (93.3%). In univariant analysis, the following risk factors were associated with failed and unreliable measurements: age over 58 years (OR = 0.49; 95% CI 0.30–0.80, p = 0.005), male gender (OR = 0.58; 95% CI 0.34–0.94, p = 0.04), BMI > 27.7 kg/m² (OR = 0.23, 95% CI 0.13–0.41, p < 0.0001). In multivariate analysis all the factors mentioned above were independently associated with the risk of failed and unreliable measurements.

Conclusions

Reliable LS measurements by means of ARFI elastography were obtained in 93.3% of cases. Older age, higher BMI and male gender were associated with the risk of failed and unreliable measurements, but their influence is limited as compared with Transient Elastography.     

Diagnostic performance of using effervescent powder for detection and grading of esophageal varices by multi-detector computed tomography

Purpose

To investigate the effect of using effervescent powder (EP) on the efficacy of multi-detector computed tomography (MDCT) in detection and grading of esophageal varices in cirrhotic patients by considering endoscopy as the gold standard.

Materials and methods

Ninety-two cirrhotic patients undergoing biphasic liver MDCT followed by upper gastrointestinal endoscopy within 4 weeks of MDCT were prospectively evaluated. The patients were divided into two groups before MDCT. The first group (n = 50) received effervescent powder (EP) before and during MDCT procedure and the second group did not receive (n = 42). The presence, size and grade of the esophageal varices were evaluated. MDCT findings were compared with endoscopic results. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of MDCT with EP and without EP were calculated and compared. Correlations between the grades of the varices for each group based on MDCT imaging and endoscopic grading were also evaluated.

Results

The sensitivity, specificity, accuracy, PPV, and NPV of MDCT were 100%, 88%, 96%, 94%, and 100%, respectively, in the EP group, whereas they were 76%, 67%, 74%, 89%, and 43%, respectively, in the non-EP group. Correlations between the grades of the esophageal varices on MDCT and endoscopy were significant in both groups (r = 0.94, p < 0.001 for EP group and r = 0.70, p < 0.001 for non-EP group).

Conclusion

During periodic CT scanning of cirrhotic patients, use of EP increases the success rate of MDCT for detection and grading of esophageal varices.     

The prevalence and characteristics of intra-atrial right coronary artery anomaly in 9,284 patients referred for coronary computed tomography angiography

Objective

To determine the prevalence, radiologic patterns and clinical characteristics of intra-atrial right coronary artery (IARCA) among adult coronary computed tomography angiography (CCTA) population.

Methods

We included 9,284 consecutive subjects who underwent CCTA at a single high-volume center. The presence of IARCA including the number, length and diameter of IARCA segments with accompanying atherosclerosis and coronary anomalies were evaluated. Additionally, clinical characteristics and midterm follow-up of IARCA patients were recorded.

Results

The IARCA prevalence was 0.15% (14/9,284) with 15 intra-atrial segments. The intra-atrial segment length ranged from 14 to 53 mm, and the mean diameter proximal to the entry site was 3.3 ± 0.7 mm. IARCA was more often associated with intramuscular course of the left anterior descending coronary artery (29% vs. 4%, p = 0.001) and anomalous origin of the left circumflex artery from the right aortic sinus (14% vs. 0.3%, p = 0.001) compared with non-IARCA cases. The majority of IARCA patients were women (86%) presenting with supraventricular arrhythmia (71%). Compared with computed tomographic population without IARCA, IARCA subjects were younger (60 ± 12 vs. 54 ± 14 years, p = 0.037) and more often women (51% vs. 86%, p = 0.013). At a mean of 20 months follow-up of IARCA patients there were no adverse cardiac events except for supraventricular tachycardia episodes occurring in 36% of subjects.

Conclusions

IARCA occurs rarely and is often associated with additional coronary anomalies. The clinical profile of IARCA patients is most often represented by middle-aged women with supraventricular arrhythmia showing favorable midterm prognosis.     

Can conventional magnetic resonance imaging predict survival in pediatric diffuse intrinsic pontine glioma? A single institution experience

Background

Pediatric diffuse intrinsic pontine glioma (DIPG) remains dismal regardless the new therapeutic and technical advances.

Objective

To investigate the value of magnetic resonance imaging (MRI) in predicting DIPG prognosis.

Patients and methods

Twenty-five DIPG patients with 95 (initial and post radiotherapy) MR examinations were studied. Hydrocephalus was detected in 6 cases (24%), basilar artery encasement in 20 (80%), ill defined border in 16 (64%), perilesional edema in 2 cases (8%) and none showed leptomeningeal spread. Conformal 3-dimensional radiotherapy (39 Gy/13 fractions or 54 Gy/30 fractions) was applied.

Results

The median overall survival (MOS) was 9.3 months (95% CI: 7.9–10.8) and the one year overall survival was 18 ± 8.9%. Post radiation MRI performed 3–6 months after treatment showed regression in 8 cases (32%), stationary course in 5 (20%) and progression in 12 cases (48%). The MOS was higher in children whose MRI showed regression (10.0, CI: 6.3–13.7) than those with radiological progression (8.0, CI: 5.9–10.1 months) or stationary course (7.0, CI: 4.9–9.1). However; these differences did not rank to the level of significance. There was no statistical association of tumor size (p = 0.907), presence of hemorrhage (p = 0.314), or surrounding edema (p = 0.263); entrapment of the basilar artery (p = 0.782); pattern of enhancement (p = 0.851); and hydrocephalus (p = 0.354) with the length of the overall survival.

Conclusions

Though MRI is the mainstay for the diagnosis of DIPG, yet its prognostic value is limited. New MR techniques as MR spectroscopy and diffusion tensor imaging should be evaluated as additional tools for prognostic evaluation of DIPG.     

Sinogram affirmed iterative reconstruction in head CT: Improvement of objective and subjective image quality with concomitant radiation dose reduction

Purpose

Iterative reconstruction has recently been revisited as a promising concept for substantial CT dose reduction. The purpose of this study was to assess the potential benefit of sinogram affirmed iterative reconstruction (SAFIRE) in head CT by comparing objective and subjective image quality at reduced tube current with standard dose filtered back projection (FBP).

Materials and methods

Non-contrast reduced dose head CT (255 mA s, CTDI_vol 47.8 mGy) was performed in thirty consecutive patients and reconstructed with SAFIRE and FBP. Images were assessed in terms of quantitative and qualitative image quality and compared with FBP of standard dose acquisitions (320 mA s, CTDI_vol 59.7 mGy).

Results

In reduced dose CT examinations, use of SAFIRE versus FBP resulted in 47% increase in contrast-to-noise ratio (CNR) (2.49 vs. 1.69; p < 0.0001). While reduction of tube current was associated with 13% decrease in CNR, quantitative degradation of image quality at lower dose was more than compensated through SAFIRE (2.49 vs. 1.96; p = 0.0004). Objective measurements of image sharpness were comparable between FBP and SAFIRE reconstructions (575.9 ± 74.1 vs. 583.4 ± 74.7 change in HU/Pixel; p = 0.28). Compared to standard dose FBP, subjective grading of noise as well as overall image quality scores were significantly improved when SAFIRE was used in reduced dose exams (1.3 vs. 1.6, p = 0.006; 1.3 vs. 1.7, p = 0.026).

Conclusion

At 20% dose reduction, reconstruction of head CT by SAFIRE provides above standard objective and subjective image quality, suggesting potential for more vigorous dose savings in neuroradiology CT applications.     

Utility and limitations of 3-Tesla diffusion-weighted magnetic resonance imaging for differentiation of renal tumors

Objective

To investigate utility and limitations of 3-Tesla diffusion-weighted (DW) magnetic resonance imaging (MRI) for differentiation of benign versus malignant renal lesions and renal cell carcinoma (RCC) subtypes.

Materials and methods

Sixty patients with 71 renal lesions underwent 3 Tesla DW-MRI of the kidney before diagnostic tissue confirmation. The images were retrospectively evaluated blinded to histology. Single-shot echo-planar imaging was used as the DW imaging technique. Apparent diffusion coefficient (ADC) values were measured and compared with histopathological characteristics.

Results

There were 54 malignant and 17 benign lesions, 46 lesions being small renal masses ≤4 cm. Papillary RCC lesions had lower ADC values (p = 0.029) than other RCC subtypes (clear cell or chromophobe). Diagnostic accuracy of DW-MRI for differentiation of papillary from non-papillary RCC was 70.3% resulting in a sensitivity and specificity of 64.3% (95% CI, 35.1–87.2) and 77.1 (95% CI, 59.9–89.6%). Accuracy increased to 83.7% in small renal masses (≤4 cm diameter) and sensitivity and specificity were 75.0% and 88.5%, respectively. The ADC values did not differ significantly between benign and malignant renal lesions (p = 0.45).

Conclusions

DW-MRI seems to distinguish between papillary and other subtypes of RCCs especially in small renal masses but could not differentiate between benign and malignant renal lesions. Therefore, the use of DW-MRI for preoperative differentiation of renal lesions is limited.     

Hepatic steatosis assessment with H-spectroscopy and chemical shift imaging at 3.0 T before hepatic surgery: Reliable enough for making clinical decisions?

Purpose

To compare the accuracy of liver fat quantification using chemical shift imaging (CSI) and H1 MR-spectroscopy (MRS) at 3.0 T in patients undergoing liver resection.

Methods

Totally 35 patients were included in this prospective IRB approved study. The histopathologically assessed liver fat was compared to the hepatic fat fractions calculated with CSI (with and without spleen correction) and MRS. Spearman's rank correlation and Fisher z-test were used for correlation analysis. Sensitivity and specificity regarding the detection of marked steatosis were calculated for the different modalities and compared using the McNemar test.

Results

MRS (r = .85) and CSI with spleen correction (r = .85) showed a significantly better correlation (p = .03) with histology compared to CSI without spleen correction (r = .67). Sensitivity and specificity for the detection of marked steatosis was 100% (12/12) and 87% (20/23) for MRS and 92% (11/12) and 83% (19/23) for CSI with spleen correction (p > .12).

Conclusion

For the assessment of hepatic steatosis both CSI with spleen correction and MRS at 3.0 T, show a good correlation with histology. CSI without spleen correction should not be used. Sensitivity and specificity for the detection of marked steatosis are high with both modalities. However, results that are scattered around the cut-off values are not reliable enough for clinical decisions.     

Optimal sequence timing of CT angiography and perfusion CT in patients with stroke

Objective

Standard stroke CT protocols start with non-enhanced CT followed by perfusion-CT (PCT) and end with CTA. We aimed to evaluate the influence of the sequence of PCT and CTA on quantitative perfusion parameters, venous contrast enhancement and examination time to save critical time in the therapeutic window in stroke patients.

Methods and materials

Stroke CT data sets of 85 patients, 47 patients with CTA before PCT (group A) and 38 with CTA after PCT (group B) were retrospectively analyzed by two experienced neuroradiologists. Parameter maps of cerebral blood flow, cerebral blood volume, time to peak and mean transit time and contrast enhancements (arterial and venous) were compared.

Results

Both readers rated contrast of brain-supplying arteries to be equal in both groups (p = 0.55 (intracranial) and p = 0.73 (extracranial)) although the extent of venous superimposition of the ICA was rated higher in group B (p = 0.04). Quantitative perfusion parameters did not significantly differ between the groups (all p > 0.18), while the extent of venous superimposition of the ICA was rated higher in group B (p = 0.04). The time to complete the diagnostic CT examination was significantly shorter for group A (p < 0.01).

Conclusion

Performing CTA directly after NECT has no significant effect on PCT parameters and avoids venous preloading in CTA, while examination times were significantly shorter.