Comparison between ROI-based and volumetric measurements in quantifying heterogeneity of liver stiffness using MR elastography

Cystic fibrosis hepatobiliary involvement: an update on imaging in diagnosis and monitoring

Analysis of the liver using imaging for persons with cystic fibrosis (CF) continues to evolve as new medical therapies are developed improving and extending life. In the 2010s, therapies targeted at modulating protein folding became available to those with CF. Therapeutic options have continued to expand, now providing both correction of protein folding and stabilization for most gene mutations that code for the CF transmembrane receptor protein (CFTR). Today, approximately 80% of persons with CF are eligible for highly effective modulator therapy. With these advancements, the impact of CF on the liver has become more complex, adding metabolism of CFTR modulators to intrinsic CF hepatobiliary involvement (CFHBI) and adding not previously appreciated vascular changes within the liver due to increased longevity in persons with CF. A combination of serum biomarkers and imaging is needed to add clarity to the diagnosis and monitoring of the severity of liver disease. A substantial portion of persons with CF will develop at least CFHBI and a subset will develop advanced cystic fibrosis-associated liver disease (aCFLD); therefore, diagnosis and monitoring need to begin in childhood. In this review, we cover the use of and need for imaging, including elastography, ultrasound, and magnetic resonance imaging (MRI), in diagnosing and monitoring CFHBI and its associated complications.

Exploring the impact of excluding intrahepatic segmental vessels on liver stiffness measurement and advanced fibrosis diagnosis using magnetic resonance elastography

BACKGROUND

The impact of excluding intrahepatic segmental vessels from regions of interest (ROIs) on liver stiffness measurement (LSM) via magnetic resonance elastography (MRE) remains uncertain.

PURPOSE

To determine the effect of excluding intrahepatic segmental vessels from ROIs on LSM obtained from MRE.

MATERIAL AND METHODS

This retrospective analysis included 95 participants who underwent successful two-dimensional gradient recalled-echo MRE before hepatic tumor resection (n = 49) or living liver donation (n = 46). The conventional LSM was determined by manually drawing ROIs on the elastogram within the 95% confidence region, staying 1 cm within the liver capsule and excluding large hilar vessels, the gallbladder, hepatic lesions, and artifacts. In addition, the modified LSM was determined by excluding intrahepatic segmental vessels. LSMs obtained by the two methods were compared with paired sample signed-rank test. Diagnostic performance for advanced fibrosis was calculated and compared using McNemar's test and Delong's test. The stage of hepatic fibrosis was assessed using surgical specimens by the METAVIR system.

RESULTS

The modified LSM was larger than the conventional LSM (2.4 kPa vs. 2.2 kPa in reader 1; 2.7 kPa vs. 2.4 kPa in reader 2; P < 0.001). The modified LSM showed superior sensitivity (0.841 vs. 0.659 in reader 1; 0.864 vs. 0.705 in reader 2; P < 0.05) and area under the curve (0.901 vs. 0.820 in reader 1; 0.912 vs. 0.843 in reader 2; P < 0.05) for detecting advanced fibrosis (≥F3) than conventional LSM.

CONCLUSION

The exclusion of intrahepatic segmental vessels from ROIs in MRE affected the LSM and enhanced diagnostic performance for advanced fibrosis.

Comparison between Gradient-Echo and Spin-Echo EPI MR Elastography at 3 T in quantifying liver stiffness of patients with and without iron overload; a prospective study

OBJECTIVES

To compare the maximum axial area of the confidence mask and the calculated liver stiffness (LS) on gradient-echo (GRE) and spin-echo echo planar imaging (SE-EPI) MR elastography (MRE) in patients with and without iron deposition.

METHODS

104 patients underwent MRE by GRE and SE-EPI sequences at 3 T. R2* values >88 Hz in the liver were categorized in the iron overload group. The maximum axial area and the corresponding LS values were measured by manually contouring the whole area on one slice with the largest confidence mask at both GRE and SE-EPI sequences.

RESULTS

In patients with iron overload, SE-EPI provided larger maximum axial confidence area in unfailed images (57.6 ± 41.7 cm²) compared to GRE (45.7 ± 29.1 cm²) (p-value = 0.007). In five patients with iron overload, imaging failed at GRE sequence, whereas at the SE-EPI sequence the maximum area of the confidence mask had a mean value of 33.5 ± 54.9 cm². In livers without iron overload (R2*: 50.7 ± 13.1 Hz), the maximum area on the confidence mask was larger at SE-EPI (118.3 ± 41.2 cm²) than on GRE (105.1 ± 31.7 cm²) (P-value = 0.003). There was no significant difference in mean LS between SE-EPI (2.0 ± 0.3 kPa) and GRE (2.1 ± 0.5 kPa) in livers with iron overload (P value = 0.24). Similarly, in the group without iron overload, mean LS was 2.3 ± 0.7 kPa at SE-EPI and 2.4 ± 0.8 kPa at GRE sequences (P-value = 0.11).

CONCLUSIONS

SE-EPI MRE can successfully provide similar LS measurements as GRE MRE. Furthermore, it provides a larger measurable area on the confidence mask in both groups with and without iron overload.

Whole-tumor histogram analysis of diffusion and perfusion metrics for noninvasive pediatric glioma grading

PURPOSE

An accurate assessment of the World Health Organization grade is vital for patients with pediatric gliomas to direct treatment planning. We aim to evaluate the diagnostic performance of whole-tumor histogram analysis of diffusion-weighted imaging (DWI) and dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI) for differentiating pediatric high-grade gliomas from pediatric low-grade gliomas.

METHODS

Sixty-eight pediatric patients (mean age, 10.47 ± 4.37 years; 42 boys) with histologically confirmed gliomas underwent preoperative MR examination. The conventional MRI features and whole-tumor histogram features extracted from apparent diffusion coefficient (ADC) and cerebral blood volume (CBV) maps were analyzed, respectively. Receiver operating characteristic curves and the binary logistic regression analysis were performed to determine the diagnostic performance of parameters.

RESULTS

For conventional MRI features, location, hemorrhage and tumor margin showed significant difference between pediatric high- and low-grade gliomas (all, P < .05). For advanced MRI parameters, ten histogram features of ADC and CBV showed significant differences between pediatric high- and low-grade gliomas (all, P < .05). The diagnostic performance of the combination of DSC-PWI and DWI (AUC = 0.976, sensitivity = 100%, NPV = 100%) is superior to conventional MRI or DWI model, respectively (AUC_cMRI = 0.700, AUC_DWI = 0.830; both, P < .05).

CONCLUSION

The whole-tumor histogram analysis of DWI and DSC-PWI is a promising method for grading pediatric gliomas.

Biological role of matrix stiffness in tumor growth and treatment

In recent years, the biological role of changes in physical factors in carcinogenesis and progression has attracted increasing attention. Matrix stiffness, also known as ECM stress, is a critical physical factor of tumor microenvironment and remains alternating during carcinogenesis as a result of ECM remodeling through activation of cancer-associated fibroblasts and extracellular collagen accumulation, crosslinking and fibrosis. Different content and density of extracellular collagen in ECM endows matrix with varying stiffness. Physical signals induced by matrix stiffness are transmitted to tumor cells primarily by the integrins receptor family and trigger a series of mechanotransduction that result in changes in tumor cell morphology, proliferative capacity, and invasive ability. Importantly, accumulating evidence revealed that changes in matrix stiffness in tumor tissues greatly control the sensitivity of tumor cells in response to chemotherapy, radiotherapy, and immunotherapy through integrin signaling, YAP signaling, and related signaling pathways. Here, the present review analyzes the current research advances on matrix stiffness and tumor cell behavior with a view to contributing to tumor cell growth and treatment, with the hope of improving the understanding of the biological role of matrix stiffness in tumors.

A novel radiomics signature based on T2-weighted imaging accurately predicts hepatic inflammation in individuals with biopsy-proven nonalcoholic fatty liver disease: a derivation and independent validation study

Background

Currently, there are no effective methods for assessing hepatic inflammation without resorting to histological examination of liver tissue obtained by biopsy. T2-weighted images (T2WI) are routinely obtained from liver magnetic resonance imaging (MRI) scan sequences. We aimed to establish a radiomics signature based on T2WI (T2-RS) for assessment of hepatic inflammation in people with nonalcoholic fatty liver disease (NAFLD).

Methods

A total of 203 individuals with biopsy-confirmed NAFLD from two independent Chinese cohorts with liver MRI examination were enrolled in this study. The hepatic inflammatory activity score (IAS) was calculated by the unweighted sum of the histologic scores for lobular inflammation and ballooning. One thousand and thirty-two radiomics features were extracted from the localized region of interest (ROI) in the right liver lobe of T2WI and, subsequently, selected by minimum redundancy maximum relevance and least absolute shrinkage and selection operator (LASSO) methods. The T2-RS was calculated by adding the selected features weighted by their coefficients.

Results

Eighteen radiomics features from Laplacian of Gaussian, wavelet, and original images were selected for establishing T2-RS. The T2-RS value differed significantly between groups with increasing grades of hepatic inflammation (P<0.01). The T2-RS yielded an area under the receiver operating characteristic (ROC) curve (AUROC) of 0.80 [95% confidence interval (CI): 0.71-0.89] for predicting hepatic inflammation in the training cohort with excellent calibration. The AUROCs of T2-RS in the internal cohort and external validation cohorts were 0.77 (0.61-0.93) and 0.75 (0.63-0.84), respectively.

Conclusions

The T2-RS derived from radiomics analysis of T2WI shows promising utility for predicting hepatic inflammation in individuals with NAFLD.

Comparison of Transient Elastography, ShearWave Elastography, Magnetic Resonance Elastography and FibroTest as routine diagnostic markers for assessing liver fibrosis in children with Cystic Fibrosis

BACKGROUND AND OBJECTIVE

Reliable markers are needed for early diagnosis and follow-up of liver disease in Cystic Fibrosis (CF). The objective was to evaluate the diagnostic performance of Transient Elastography (TE), Real-Time ShearWave Ultrasound Elastography (SWE), Magnetic Resonance Elastography (MRE) and the FibroTest as markers of Cystic Fibrosis Liver Disease (CFLD).

METHODS

A monocentric prospective cross-modality comparison study was proposed to all children (6 to 18 years of age) attending the CF center. Based on liver ultrasound findings, participants were classified into 3 groups: multinodular liver or portal hypertension (Nodular US/PH, advanced CFLD), heterogeneous increased echogenicity (Heterogeneous US, CFLD) or neither (Normal/Homogeneous US, no CFLD). The 4 tests were performed on the same day. The primary outcome was the FibroTest value and liver stiffness measurements (LSM).

RESULTS

55 participants (mean age 12.6 ± 3.3 years; 25 girls) were included between 2015 and 2018: 23 in group Nodular US/PH, 8 in group Heterogeneous US and 24 in group Normal/Homogeneous US (including 4 with steatosis). LSM on TE, SWE and MRE were higher in participants with CFLD (groups Nodular US/PH and Heterogeneous US) compared to others (group Normal/Homogeneous US) (p<0.01), while FibroTest values did not differ (p = 0.09). The optimal cut-off values for predicting CFLD on TE, SWE and MRE were 8.7 (AUC=0.83, Se=0.71, Sp=0.96), 7.8 (AUC=0.85, Se=0.73, Sp=0.96) and 4.15 kPa (AUC=0.68, Se=0.73, Sp=0.64), respectively. LSM predicted the occurrence of major liver-related events at 3 years. TE and SWE were highly correlated (Spearman's ρ=0.9) and concordant in identifying advanced CFLD (Cohen's κ=0.84) while MRE was moderately correlated and concordant with TE (ρ=0.41; κ=36) and SWE (ρ=0.5; κ=0.50).

CONCLUSION

This study demonstrated excellent diagnostic performance of TE, SWE and MRE for the diagnosis of CFLD.

Automated CNN-Based Analysis Versus Manual Analysis for MR Elastography in Nonalcoholic Fatty Liver Disease: Inter-method Agreement and Fibrosis Stage Discriminative Performance

Background: Histological fibrosis stage is the most important prognostic factor in chronic liver disease. MR elastography (MRE) is the most accurate noninvasive method for detecting and staging liver fibrosis. Although accurate, manual ROI-based MRE analysis is complex, time consuming, requires specialized readers, and prone to methodologic variability and suboptimal inter-reader agreement. Objectives: To develop an automated convolutional neural network (CNN)-based method for liver MRE analysis, evaluate its agreement with manual ROI-based analysis, and assess its discriminative performance for dichotomized fibrosis stages using histology as reference standard. Methods: In this retrospective cross-sectional study, 675 participants who underwent MRE using different MRI systems and field strengths at 28 imaging sites from five multicenter international clinical trials of nonalcoholic steatohepatitis were included for algorithm development and internal testing of agreement between automated CNN- and manual ROI-based analyses. Eighty-one patients (52 women, 29 men; mean age, 54 years) who underwent MRE using a single 3-Tesla system and liver biopsy for clinical purposes at a single institution were included for external testing of agreement and assessment of fibrosis stage discriminative performance. Agreement was evaluated using intra-class correlation coefficients (ICC). 95% CIs were computed using bootstrapping. Discriminative performance of each method for dichotomized histologic fibrosis stage was evaluated by AUC and compared using bootstrapping. Results: Mean CNN- and manual ROI-based stiffness measurements ranged from 3.21 to 3.34 kPa in trial participants and from 3.30 to 3.45 kPa in clinical patients. ICC for CNN- and manual ROI-based measurements was 0.98 (95% CI, 0.978-0.98) in trial participants and 0.99 (95% CI: 0.98-0.99) in clinical patients. AUC for classification of dichotomized fibrosis stage ranged from 0.89-0.93 for CNN- and 0.87-0.93 for manual ROI-based analyses (p=.23-.75). Conclusion: Stiffness measurements using the automated CNN-based method agreed strongly with manual ROIbased analysis across MRI systems and field strengths, with excellent discriminative performance for histology-determined dichotomized fibrosis stages in external testing. Clinical Impact: Given the high incidence of chronic liver disease worldwide, it is important that noninvasive tools to assess fibrosis are applied reliably across different settings. CNN-based analysis is feasible and may reduce reliance on expert image analysts.

Cystic fibrosis-related liver disease: Clinical presentations, diagnostic and monitoring approaches in the era of CFTR modulator therapies

Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population. Cystic fibrosis-related liver disease (CFLD) is defined as the pathogenesis related to the underlying CFTR defect in biliary epithelial cells. CFLD needs to be distinguished from other liver manifestations that may not have any pathological significance. The clinical/histological presentation and severity of CFLD vary. The main histological presentation of CFLD is focal biliary fibrosis, which is usually asymptomatic. Portal hypertension develops in a minority of cases (about 10%) and may require specific management including liver transplantation for end-stage liver disease. Portal hypertension is usually the result of the progression of focal biliary fibrosis to multilobular cirrhosis during childhood. Nevertheless, non-cirrhotic portal hypertension as a result of porto-sinusoidal vascular disease is now identified increasingly more frequently, mainly in young adults. To evaluate the effect of new CFTR modulator therapies on the liver, the spectrum of hepatobiliary involvement must first be precisely classified. This paper discusses the phenotypic features of CFLD, its underlying physiopathology and relevant diagnostic and follow-up approaches, with a special focus on imaging.

Investigating the heterogeneity of viscoelastic properties in prostate cancer using MR elastography at 9.4T in fresh prostatectomy specimens

PURPOSE

To quantify the heterogeneity of viscoelastic tissue properties in prostatectomy specimens from men with prostate cancer (PC) using MR elastography (MRE) with histopathology as reference.

METHODS

Twelve fresh prostatectomy specimens were examined in a preclinical 9.4T MRI scanner. Maps of the complex shear modulus (|G*| in kPa) with its real and imaginary part (G' and G" in kPa) were calculated at 500 Hz. Prostates were divided into 12 segments for segment-wise measurement of viscoelastic properties and histopathology. Coefficients of variation (CVs in %) were calculated for quantification of heterogeneity.

RESULTS

Group-averaged values of cancerous vs. benign segments were significantly increased: |G*| of 12.13 kPa vs. 6.14 kPa, G' of 10.84 kPa vs. 5.44 kPa and G" of 5.45 kPa vs. 2.92 kPa, all p < 0.001. In contrast, CVs were significantly increased for benign segments: 23.59% vs. 26.32% (p = 0.014) for |G*|, 27.05% vs. 37.84% (p < 0.003) for G', and 36.51% vs. 50.37% (p = 0.008) for G".

DISCUSSION

PC is characterized by a stiff yet homogeneous biomechanical signature, which may be due to the unique nondestructive growth pattern of PC with intervening stroma, providing a rigid scaffold in the affected area. In turn, increased heterogeneity in benign prostate segments may be attributable to the presence of different prostate zones with involvement by specific nonmalignant pathology.

Assessing the progression of segmental fibrosis in chronic liver disease using extracellular volume fractions

PURPOSE

To assess the segmental difference of liver fibrosis during the progression of chronic liver disease (CLD) using hepatic extracellular volume fractions (fECVs) obtained by dual-energy CT.

METHODS

A total of 218 patients (92 men and 126 women; mean age, 67.8 ± 11.7 years) with CLD and 85 patients (44 men and 41 women; mean age, 62.8 ± 13.7 years) without CLD as a control underwent dual-energy computed tomography (CT) of the liver (5-min equilibrium phase images). The iodine densities of the lateral, medial, anterior, and posterior segments and the aorta were measured, and fECVs were calculated. Comparisons of the fECV of each segment and for each albumin-bilirubin (ALBI) grade were then statistically analyzed.

RESULTS

In the control group and ALBI grades 1 and 3, no significant difference in fECV was found between each segment, whereas in ALBI grade 2, the fECVs were significantly larger in the medial and anterior than in the other segments (p < 0.001). The fECVs of the lateral and posterior segments significantly increased with higher ALBI grade (p < 0.001). The fECVs of the medial and anterior segments were significantly increased with higher ALBI grade, up to grade 2 (p < 0.001), but no significant difference was found between ALBI grades 2 and 3.

CONCLUSION

During the progression of CLD, fibrosis antecedently progressed in the medial and anterior segments, followed by the other liver segments.

Diagnostic accuracy of 3D magnetic resonance elastography for assessing histologic grade of hepatocellular carcinoma: comparison of three methods for positioning region of interest

PURPOSE

To assess the influence of region of interest (ROI) placement on the predictive value of 3D MRE in differentiating the histologic grade of HCC.

METHODS

85 patients with pathologically confirmed HCCs were analyzed using 3D MRE imaging, two radiologists measured the tumor stiffness with three different ROI positioning methods. Intraclass correlation coefficient (ICC) was expressed in terms of inter- and intra-observer agreements. Kruskal-Wallis rank test or one-way ANOVA was used to compare the difference in MRE stiffness across the three-ROI positioning methods. Receiver operating characteristic curve analysis (ROC) was performed, and the area under curve (AUC) was measured to evaluate the diagnostic performance.

RESULTS

There were 64 (75%) well-or-moderately differentiated HCCs and 21(25%) poorly differentiated HCCs included finally. Almost excellent inter- and intra-observer agreements (all ICC > 0.82) were observed for all three-ROI methods, the volumetric method has the highest values (inter-observer ICC 0.967, intra-observer ICC 0.919, 0.926, respectively). The mean stiffnesses of poorly differentiated HCC obtained by two readers were significantly higher than well-or-moderately differentiated HCC with volumetric method (7.07 ± 1.57 Kpa, 5.00 ± 1.49 Kpa, and 6.85 ± 1.49 Kpa, 4.94 ± 1.48 Kpa, respectively) and three-ROI method (6.14 ± 1.71 Kpa, 4.91 ± 1.56 Kpa and 5.94 ± 1.61 Kpa, 4.84 ± 1.54 Kpa, respectively) but not on single-ROI method (p > 0.005), for the diagnostic performance, the highest area under the curve (AUC) with a value of 0.837, 0.812 by using the volumetric method, followed by the three-ROI method (0.713, 0.754) and single-ROI method.

CONCLUSION

Different ROI positioning methods significantly affect HCC tumor stiffness measurements. The whole tumor volumetric analysis is superior to ROI-based methods for predicting the grade of HCC.

Spatial heterogeneity of hepatic fibrosis in primary sclerosing cholangitis vs. viral hepatitis assessed by MR elastography

Spatial heterogeneity of hepatic fibrosis in primary sclerosing cholangitis (PSC) in comparison to viral hepatitis was assessed as a potential new biomarker using MR elastography (MRE). In this proof-of-concept study, we hypothesized a rather increased heterogeneity in PSC and a rather homogeneous distribution in viral hepatitis. Forty-six consecutive subjects (PSC: n = 20, viral hepatitis: n = 26) were prospectively enrolled between July 2014 and April 2017. Subjects underwent multifrequency MRE (1.5 T) using drive frequencies of 35–60 Hz and generating shear-wave speed (SWS in m/s) maps as a surrogate of stiffness. The coefficient of variation (CV in %) was determined to quantify fibrosis heterogeneity. Mean SWS and CV were 1.70 m/s and 21% for PSC, and 1.84 m/s and 18% for viral hepatitis. Fibrosis heterogeneity was significantly increased for PSC (P = 0.04) while no difference was found for SWS of PSC and viral hepatitis (P = 0.17). Global hepatic stiffness was similar in PSC and viral hepatitis groups, but spatial heterogeneity may reveal spatial patterns of stiffness changes towards enhanced biophysics-based diagnosis by MRI.

Role of volumetric multiparametric MRI in distinguishing between intraductal papillary mucinous neoplasms and serous cystadenoma

PURPOSE

To evaluate the use of volumetric multiparametric MRI in differentiating pancreatic intraductal papillary mucinous neoplasms (IPMNs) from serous cystadenomas (SCAs) METHODS: Included patients (123 patients with pancreatic cystic neoplasms (PCNs) measuring ≥ 10 mm) were stratified into two groups based on cyst type. Axial cyst size, region of interest (ROI)-based apparent diffusion coefficient (ADC) and volumetric data, including cyst volume, volumetric apparent diffusion coefficient (vADC), and volumetric venous enhancement (vVE) were extracted and compared between the two groups. Univariate and multiple logistic regression was used to develop models for distinguishing between IPMNs and SCAs.

RESULTS

Volume and size of the cysts, vVE and vADC and ROI-ADC were significantly different between the two groups. Cyst volume was significantly larger in SCAs (median = 14.1cm³, IQR 3.5-42.5) than in IPMNs (median = 2.5 cm³, IQR 1.1-6) (p < 0.001). IPMNs had a higher volumetric ADC value in comparison to SCAs (2925 ± 294 × 10^-6 mm²/s vs 2521 ± 202 × 10^-6 mm²/s, p < 0.001). However, IPMNs had lower vVE values compared to SCAs (37 signal intensity (SI) vs 86 SI, p < 0.001). Area under the ROC Curve (AUC) of the model that included vADC and cyst volume had 95% accuracy in distinguishing between the two groups. In comparison, the AUC of the model that included ROI-ADC and axial cyst size had 84% accuracy in distinguishing between the two groups. A threshold of 2615 × 10^-6 mm²/s for volumetric ADC resulted in the identification of IPMNs from SCAs with sensitivity and specificity of 90.8% and 73.5%, respectively.

CONCLUSION

IPMNs had smaller cyst volume, higher volumetric ADC and lower volumetric VE values compared to SCAs. Volumetric multiparametric MRI could be useful in differentiating between the IPMN and SCA groups.

Feasibility of T1 mapping with histogram analysis for the diagnosis and staging of liver fibrosis: Preclinical results

PURPOSE

To compare the diagnostic accuracy of parameters derived from the histogram analysis of precontrast, 10-min hepatobiliary phase (HBP) and 20-min HBP T1 maps for staging liver fibrosis (LF).

METHODS

LF was induced in New Zealand white rabbits by subcutaneous injections of carbon tetrachloride for 4-16 weeks (n = 120), and 20 rabbits injected with saline served as controls. Precontrast, 10-min and 20-min HBP modified Look-Locker inversion recovery (MOLLI) T1 mapping was performed. Histogram analysis of T1 maps was performed, and the mean, median, skewness, kurtosis, entropy, inhomogeneity and 10th/25th/75th/90th percentiles of T1_native, T1_10min and T1_20min were derived. Quantitative histogram parameters were compared. For significant parameters, further receiver operating characteristic (ROC) analyses were performed to evaluate the potential diagnostic performance in differentiating LF stages.

RESULTS

Finally, 17, 20, 21, 21 and 20 rabbits were included for the F0, F1, F2, F3, and F4 pathological grades of fibrosis, respectively. The mean/75th of T1_native, entropy of T1_10min and entropy/mean/median/10th of T1_20min demonstrated a significant good correlation with the LF stage (|r| = 0.543-0.866, all P < 0.05). The 75th of T1_native, entropy_10min, and entropy_20min were the three most reliable imaging markers in reflecting the stage of LF. The area under the ROC curve of entropy_20min was larger than that of entropy_10min (P < 0.05 for LF ≥ F2, ≥F3, and ≥ F4) and the 75th of T1_native (P < 0.05 for LF ≥ F2 and ≥ F3) for staging LF.

CONCLUSION

Magnetic resonance histogram analysis of T1 maps, particularly the entropy derived from 20-min HBP T1 mapping, is promising for predicting the LF stage.

Role of tumor margin and ADC change in defining the need for additional treatments after the first TACE in patients with unresectable HCC

PURPOSE

To define the number of TACE sessions needed to improve patients' overall survival (OS) in different subgroups of unresectable HCC.

METHODS

This retrospective cohort included 180 patients who got TACE between 2005-2016 as the initial treatment for unresectable HCC. Tumor margin (well- vs. ill-defined) was determined by two radiologists at baseline. Well-defined group was divided into two groups (ADC-responders vs. ADC-nonresponders) based on %ADC change (ΔADC-cutoff = 25 %). Accordingly, patients were categorized into three groups, ill-defined, well-defined ADC-responders, or well-defined ADC-nonresponders. Cox-analysis was used to compare the survival benefit of multiple TACE in different groups.

RESULTS

Ill-defined HCC (n = 108) was associated with worse survival (HR = 1.95,p < 0.001). Multiple TACE were associated with increased OS (HR = 0.88,p = 0.033) in these patients, with significant survival improvement after ≥4TACE. ΔADC was not related to OS in ill-defined group. In well-defined group (n = 72), multiple TACE were not associated with improved OS (HR = 0.181,p = 0.090). These patients were categorized into two groups based on ΔADC-cutoff. ADC-responders (ΔADC≥25 %) had the longest survival than other groups(p = 0.015). Multiple TACE sessions were not associated with better OS in this group (HR = 1.004,p = 0.982). By contrast, incremental number of TACE were associated with significantly longer OS in ADC-nonresponders (ΔADC<25 %) (HR = 0.79,p = 0.034). These patients' OS significantly improved after ≥3TACE.

CONCLUSION

The survival benefit of sequential TACE sessions varies for different HCC subgroups. There was no significant survival benefit associated with multiple TACE in well-defined lesions responding to the first TACE. The most survival benefit was for ADC-nonresponder well-defined group and it was least for ill-defined HCC group, regardless of ADC-response.

MR elastography of liver: current status and future perspectives

Non-invasive evaluation of liver fibrosis has evolved over the last couple of decades. Currently, elastography techniques are the most widely used non-invasive methods for clinical evaluation of chronic liver disease (CLD). MR elastography (MRE) of the liver has been used in the clinical practice for nearly a decade and continues to be widely accepted for detection and staging of liver fibrosis. With MRE, one can directly visualize propagating shear waves through the liver and an inversion algorithm in the scanner automatically converts the shear wave properties into an elastogram (stiffness map) on which liver stiffness can be calculated. The commonly used MRE method, two-dimensional gradient recalled echo (2D-GRE) sequence has produced excellent results in the evaluation of liver fibrosis in CLD from various etiologies and newer clinical indications continue to emerge. Advances in MRE technique, including 3D MRE, automated liver elasticity calculation, improvements in shear wave delivery and patient experience, are promising to provide a faster and more reliable MRE of liver. Innovations, including evaluation of mechanical parameters, such as loss modulus, displacement, and volumetric strain, are promising for comprehensive evaluation of CLD as well as understanding pathophysiology, and in differentiating various etiologies of CLD. In this review, the current status of the MRE of liver in CLD are outlined and followed by a brief description of advanced techniques and innovations in MRE of liver.

Advances in Imaging of Diffuse Parenchymal Liver Disease

There are >1.5 billion people with chronic liver disease worldwide, causing liver diseases to be a significant global health issue. Diffuse parenchymal liver diseases, including hepatic steatosis, fibrosis, metabolic diseases, and hepatitis cause chronic liver injury and may progress to fibrosis and eventually hepatocellular carcinoma. As early diagnosis and treatment of these diseases impact the progression and outcome, the need for assessment of the liver parenchyma has increased. While the current gold standard for evaluation of the hepatic parenchymal tissue, biopsy has disadvantages and limitations. Consequently, noninvasive methods have been developed based on serum biomarkers and imaging techniques. Conventional imaging modalities such as ultrasound, computed tomography scan, and magnetic resonance imaging provide noninvasive options for assessment of liver tissue. However, several recent advances in liver imaging techniques have been introduced. This review article focuses on the current status of imaging methods for diffuse parenchymal liver diseases assessment including their diagnostic accuracy, advantages and disadvantages, and comparison between different techniques.