Peng-Ju Xu

Added value of breathhold diffusion-weighted MRI in detection of small hepatocellular carcinoma lesions compared with dynamic contrast-enhanced MRI alone using receiver operating characteristic curve analysis.

To evaluate the added value of single‐breathhold diffusion‐weighted MRI (DWI) in detection of small hepatocellular carcinoma (HCC) lesions (≤2 cm) in patients with chronic liver disease, by comparing the detection sensitivity of combined DWI/conventional dynamic contrast‐enhanced (DCE)‐MRI to that of conventional DCE‐MRI alone.

Contribution of diffusion-weighted magnetic resonance imaging in the characterization of hepatocellular carcinomas and dysplastic nodules in cirrhotic liver.

Objectives: To evaluate the diagnostic value of diffusion-weighted magnetic resonance imaging (DWI) for the characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in cirrhotic liver, compared with contrast material-enhanced magnetic resonance imaging (CE-MRI). Methods: A total of 54 patients with 40 HCC and 19 DN lesions were included in our study, and all lesions were histopathologically confirmed. All lesions were evaluated with CE-MRI, and breath-hold DWI was performed with b = 500 s/mm2. The signal intensity (SI) of the lesions were classified as low, iso-, slightly high, and strongly high SI compared with that of the surrounding liver parenchyma on DWI for qualitative assessment. Apparent diffusion coefficients (ADCs) and lesion-to-liver ADC ratio of HCCs and DNs were measured and compared by using the Mann-Whitney U test. The lesions were characterized with the use of CE-MRI criteria and DWI, respectively. Receiver operating characteristic analysis was performed to assess the diagnostic value of DWI, CE-MRI, and these techniques combined in the differentiation of HCCs from DNs. Results: In the qualitative analysis, among 40 HCCs, 39 (97.5%) had slightly high or strongly high SI on DWI, and 1 (2.5%) had low SI; only 4 (21.5%) of 19 DNs had slightly high SI, and 15 (78.95%) had iso-SI or low SI. The mean (SD) ADC and ADC ratio for HCCs (1.28 × 10−3 [0.25] mm2/s and 0.88 [0.15], respectively) were significantly lower (P < 0.01 and P < 0.001, respectively) than those for DNs (1.53 × 10−3 [0.33] mm2/s and 1.00 [0.08], respectively). The area, Az, under the receiver operating characteristic curve for the SI feature, the ADC ratio, and the ADCs based on the diagnosis of HCC versus DN were 0.88, 0.81, and 0.68, respectively. When the slightly high SI of lesion with a cutoff ADC ratio less than 0.92 was applied as a criterion, the Az, the sensitivity, the specificity, and the accuracy of DWI for the diagnosis of HCC versus DN were 0.81, 67.50%, 94.74%, and 76.27%, respectively. The corresponding Az, sensitivity, specificity, and accuracy of CE-MRI were 0.70, 82.50%, 57.89%, and 74.58%, respectively. Combined DWI plus CE-MRI had 0.91 Az, 97.50% sensitivity, and 93.22% accuracy, which increased significantly compared with those of CE-MRI alone. Conclusions: Diffusion-weighted MRI can provide additional information to differentiate HCC from DN. Combined with CE-MRI, DWI allows improved characterization of HCC versus DN in cirrhotic liver.

Utilizing generalized autocalibrating partial parallel acquisition (GRAPPA) to achieve high-resolution contrast-enhanced MR angiography of hepatic artery: initial experience in orthotopic liver transplantation candidates

Objective: To evaluate feasibility of using GRAPPA to acquire high-resolution 3D contrast-enhanced MR angiography (CE-MRA) of hepatic artery and value of GRAPPA for displaying vessels anatomy. Materials and methods: High-resolution CE-MRA using GRAPPA was performed in 67 orthotopic liver transplantation recipient candidates. Signal intensity (SI) and relative SI, i.e., Cv-ro (vessel-to-liver contrast) of the aorta and the hepatic common artery (HCA), were measured. The SI and the relative SI were compared and analyzed using T-test. For purpose of qualitative evaluation, the vessel visualization quality and the order of depicted hepatic artery branches were evaluated by two radiologists independently and assessed by weighted kappa analysis. The depiction of hepatic arterial anatomy and variations was evaluated, and results were correlated with the findings in surgery. Results: The mean SI values were 283.29 ± 65.07 (mean ± S.D.) for aorta and 283.16 ± 64.07 for HCA, respectively. The mean relative SI values were 0.698 ± 0.09 for aorta and 0.696 ± 0.09 for HCA, respectively. Homogeneous enhancement between aorta and HCA was confirmed by statistically insignificant differences (p-values were 0.89 for mean SI values and 0.12 for mean relative SI values, respectively). The average score for vessel visualization ranged from good to excellent for different artery segments. Overall interobserver agreement in the visualization of different artery segments was excellent (kappa value > 0.80). The distal intrahepatic segmental arteries were well delineated for majority of patients with excellent interobserver agreement. Normal hepatic arterial anatomy was correctly demonstrated in 53 patients, and arterial anomalies were accurately detected on high-resolution MRA image of all 14 patients. Conclusion: High-resolution hepatic artery MRA acquired using GRAPPA in a reproducible manner excellently depicts and delineates small vessels and can be routinely used for evaluating OLT candidates.

Evaluation of Computer-Assisted Quantitative Volumetric Analysis for Pre-Operative Resectability Assessment of Huge Hepatocellular Carcinoma

PURPOSE Hepatic resection is arguably the preferred treatment for huge hepatocellular carcinoma (H-HCC). Estimating the remnant liver volume is therefore essential. This study aimed to evaluate the feasibility of using computer-assisted volumetric analysis for this purpose. METHODS The study involved 40 patients with H-HCC. Laboratory examinations were conducted, and a contrast CT-scan revealed that 30 cases out of the participating 40 had single-lesion tumors. The remaining 10 had less than three satellite tumors. With the consensus of the team, two physicians conducted computer-assisted 3D segmentation of the liver, tumor, and vessels in each case. Volume was automatically computed from each segmented/labeled anatomical field. To estimate the resection volume, virtual lobectomy was applied to the main tumor. A margin greater than 1 cm was applied to the satellite tumors. Resectability was predicted by computing a ratio of functional liver resection (R) as (Vresected- Vtumor)/(Vtotal-Vtumor) x 100%, applying a threshold of 50% and 60% for cirrhotic and non-cirrhotic cases, respectively. This estimation was then compared with surgical findings. RESULTS Out of the 22 patients who had undergone hepatectomies, only one had an R that exceeded the threshold. Among the remaining 18 patients with non-resectable H-HCC, 12 had Rs that exceeded the specified ratio and the remaining 6 had Rs that were < 50%. Four of the patients who had Rs less than 50% underwent incomplete surgery due to operative findings of more extensive satellite tumors, vascular invasion, or metastasis. The other two cases did not undergo surgery because of the high risk involved in removing the tumor. Overall, the ratio of functional liver resection for estimating resectability correlated well with the other surgical findings. CONCLUSION Efficient pre-operative resectability assessment of H-HCC using computer-assisted volumetric analysis is feasible.

Comprehensive assessment of aortic compliance and brachial endothelial function using 3.0-T high-resolution MRI: a feasibility study.

Objectives To investigate the feasibility of one-stop examination of aortic pulse wave velocity (PWV) , aortic distensibility (AD), and brachial artery flow-mediated dilation (FMD) in healthy volunteers by means of 3.0-T high-resolution magnetic resonance imaging (MRI). Methods A total of 32 healthy volunteers (24-37 years old; mean age, 29 years) underwent repeated high-resolution MRI to assess aortic PWV, ascending aorta (AA) AD, proximal descending aorta (PDA) AD, distal descending aorta (DDA) AD, and FMD of the brachial artery with an interval of 1 to 2 hours. Pulse wave velocity was evaluated by 2-dimensional (2D) phase contrast velocity-encoded MRI with a 4.7- to 7.8-millisecond (ms) temporal resolution. Fiesta-cine MRI was used to assess AD and FMD with a 18.75- to 31.25-ms temporal resolution. The image quality of repeated scans was evaluated with 4-point scores, and the agreement between the 2 scans was tested with kappa analysis. The reproducibility of the results from repeated measurements for PWV, AA-AD, PDA-AD, DDA-AD, and FMD was assessed with intraclass correlation coefficient (ICC) analysis. The method of Bland-Altman plot was also used to assess the agreement between repeated measurements. Results Each examination including PWV, AD, and FMD were completed in approximately half an hour. The image quality between repeated scans showed good agreement (&kgr; value, 0.776) with a mean score of 3.53 and 3.41, respectively. Reproducibility between repeated measurements was high for aortic PWV (4.33 ± 0.88 vs 4.36 ± 0.88 m/s; ICCPWV = 0.95; P < 0.01), AA-AD (8.60 ± 3.11 vs 8.59 ± 3.10 × 10−3 mm Hg−1; ICCAA-AD = 0.97; P < 0.01), PDA-AD (6.95 ± 2.44 vs 6.95 ± 2.42 × 10−3 mm Hg−1; ICCPDA-AD = 0.99; P < 0.01), DDA (10.54 ± 2.91 vs 10.55 ± 2.90 × 10−3mm Hg−1; ICCDDA-AD = 0.98, P < 0.01), and FMD (24.94 ± 12.55 vs 24.92 ± 12.38%; ICCFMD = 0.94, P < 0.01). Good agreement between repeated measurements was found for aortic PWV (confidence interval [CI], −0.55 to 0.50), AA-AD (CI, −0.11 to 0.12), PDA-AD (CI, −0.08 to 0.08), DDA-AD (CI, −0.23 to 0.21), and FMD (CI, −1.46 to 1.51). Conclusion Comprehensive assessment of aortic compliance and brachial endothelial function can be achieved in a single examination using 3.0-T high-resolution MRI with good reproducibility and within a reasonable amount of time.

ADCtotal ratio and D ratio derived from intravoxel incoherent motion early after TACE are independent predictors for survival in hepatocellular carcinoma

To explore the threshold of intravoxel incoherent motion (IVIM) parameters, apparent diffusion coefficient [ADCtotal and ADC(0,500)] ratios 24–48 hours after transarterial chemoembolization (TACE) to assess early response in patients with unresectable hepatocellular carcinoma (HCC) and to compare the association between diffusion‐weighted imaging with the intravoxel incoherent motion (IVIM‐DWI) and mRECIST with survival.

Pre-TACE kurtosis of ADC total derived from histogram analysis for diffusion-weighted imaging is the best independent predictor of prognosis in hepatocellular carcinoma

PurposeTo determine the feasibility of pre-TACE IVIM imaging based on histogram analysis for predicting prognosis in the treatment of unresectable hepatocellular carcinoma (HCC).Materials and methodsFifty-five patients prospectively underwent 1.5T MRI 1 week before TACE. Histogram metrics for IVIM parameters and ADCs maps between responders and non-responders with mRECIST assessment were compared. Kaplan–Meier, log-rank tests and Cox proportional hazard regression model were used to correlate variables with time to progression (TTP).ResultsMean (p = 0.022), median (p = 0.043), and 25th percentile (p < 0.001) of perfusion fraction (PF), mean (p < 0.001), median (p < 0.001), 25th percentile (p < 0.001) and 75th percentile (p = 0.001) of ADC(0,500), mean (p = 0.005), median (p = 0.008) and 25th percentile (p = 0.039) of ADCtotal were higher, while skewness and kurtosis of PF (p = 0.001, p = 0.005, respectively), kurtosis of ADC(0,500) and ADCtotal (p = 0.005, p = 0.001, respectively) were lower in responders compared to non-responders. Multivariable analysis demonstrated that mRECIST was associated with TTP independently, and kurtosis of ADCtotal had the best predictive performance for disease progression.ConclusionPre-TACE kurtosis of ADCtotal is the best independent predictor for TTP.Key Points• mRECIST was associated with TTP independently.• Lower kurtosis and higher mean for ADCs tend to have good response.• Pre-TACE kurtosis of ADCtotalis the best independent predictor for TTP.