Performance of magnetic resonance elastography and diffusion-weighted imaging for the staging of hepatic fibrosis: A meta-analysis

Comparison and optimization of b value combinations for diffusion-weighted imaging in discriminating hepatic fibrosis

INTRODUCTION AND OBJECTIVES

Diffusion-weighted imaging (DWI) has shown potential in characterizing hepatic fibrosis. However, there are no widely accepted apparent diffusion coefficient (ADC) values for the b value combination. This study aims to determine the optimal high and low b values of DWI to assess hepatic fibrosis in patients with chronic liver disease.

MATERIALS AND METHODS

The prospective study included 81 patients with chronic liver disease and 21 healthy volunteers who underwent DWI, Magnetic resonance elastography (MRE), and liver biopsy. The ADC was calculated by twenty combinations of nine b values (0, 50, 100, 150, 200, 800, 1000, 1200, and 1500 s/mm2).

RESULTS

All ADC values of the healthy volunteers were significantly higher than those of the hepatic fibrosis group (all P < 0.01). With the progression of hepatic fibrosis, ADC values significantly decreased in b value combinations (100 and 1000 s/mm2, 150 and 1200 s/mm2, 200 and 800 s/mm2, and 200 and 1000 s/mm2). ADC values derived from b values of both 200 and 800 s/mm2 and 200 and 1000 s/mm2 were found to be more discriminative for differentiating the stages of hepatic fibrosis. An excellent correlation was between the ADC200-1000 value and MRE shear stiffness (r = - 0.750, P < 0.001).

CONCLUSION

DWI offers an alternative to MRE as a useful imaging marker for detecting and staging hepatic fibrosis. Clinically, ADC values for b values ranging from 200-800 s/mm2 to 200-1000 s/mm2 are recommended for the assessment of hepatic fibrosis.

Diagnostic Performance of Quantitative Ultrasound Parameters in Non-alcoholic Fatty Liver Disease

RATIONALE AND OBJECTIVES

Marked liver steatosis, steatohepatitis, and significant fibrosis are risk factors for unfavorable outcomes in non-alcoholic fatty liver disease (NAFLD). In this study, the diagnostic performance of attenuation coefficient (AC), liver stiffness (LS), and dispersion slope (DS) was evaluated separately and combined in the diagnosis of liver steatosis and fibrosis in NAFLD suspects using biopsy or magnetic resonance imaging (MRI) as a reference standard.

MATERIALS AND METHODS

Seventy-four NAFLD suspects were prospectively imaged with an Aplio i800 ultrasound scanner (Canon Medical Systems, Tustin, CA). AC, LS, and DS measurements were obtained from the right liver lobe.

RESULTS

Thirty-four patients underwent liver biopsy, and 40 had MRI. There were 32 patients (43%) with liver steatosis and fibrosis (S + F), 22 (30%) with steatosis (S), 5 (7%) with fibrosis (F), and 15 (20%) with normal liver (N). Mean ACs were significantly higher in steatotic livers (n = 54) than in non-steatotic livers (n = 20) (P < 0.0001). LS and DS were significantly higher in patients with liver fibrosis (n = 37) compared to non-fibrotic livers (n = 37) (P = 0.0004 and P = 0.0002, respectively). In detecting (S + F), the area under the receiver operating characteristic curve (AUROCC) was 0.87 for combined ultrasound parameters of LS and AC (negative predictive value [NPV]: 75%, positive predictive value [PPV]: 77%, P < 0.0001). In detecting patients with liver steatosis and fibrosis stage ≥2, LS had an AUROCC of 0.93 (NPV: 87%, PPV: 82%, P < 0.0001). In the biopsy group, 32% (11/34) were diagnosed with non-alcoholic steatohepatitis (NASH). DS values showed a significant difference among patients with (n = 23) or without (n = 11) hepatocellular ballooning (P = 0.02). AUROCC was 0.87 for combined ultrasound parameters of AC, LS, and DS with body mass index (BMI) in detecting NASH (NPV: 80%, PPV: 87%, P = 0.0006).

CONCLUSION

AC and LS showed high diagnostic value in detecting liver steatosis and fibrosis, respectively. The combined AC and LS values further improved the diagnostic accuracy in detecting NAFLD and high-risk NAFLD patients.

Comparison between Intravoxel Incoherent Motion and Splenic Volumetry to Predict Hepatic Fibrosis Staging in Preoperative Patients

Intravoxel incoherent motion (IVIM) and splenic volumetry (SV) for hepatic fibrosis (HF) prediction have been reported to be effective. Our purpose is to compare the HF prediction of IVIM and SV in 67 patients with pathologically staged HF. SV was divided by body surface area (BSA). IVIM indices, such as slow diffusion-coefficient related to molecular diffusion (D), fast diffusion-coefficient related to perfusion in microvessels (D*), apparent diffusion-coefficient (ADC), and perfusion related diffusion-fraction (f), were calculated by two observers (R1/R2). D (p = 0.718 for R1, p = 0.087 for R2) and D* (p = 0.513, p = 0.708, respectively) showed a poor correlation with HF. ADC (p = 0.034, p = 0.528, respectively) and f (p < 0.001, p = 0.007, respectively) decreased as HF progressed, whereas SV/BSA increased (p = 0.015 for R1). The AUCs of SV/BSA (0.649-0.698 for R1) were higher than those of f (0.575-0.683 for R1 + R2) for severe HF (≥F3-4 and ≥F4), although AUCs of f (0.705-0.790 for R1 + R2) were higher than those of SV/BSA (0.628 for R1) for mild or no HF (≤F0-1). No significant differences to identify HF were observed between IVIM and SV/BSA. SV/BSA allows a higher estimation for evaluating severe HF than IVIM. IVIM is more suitable than SV/BSA for the assessment of mild or no HF.

Liver cirrhosis in children - the role of imaging in the diagnostic pathway

Liver cirrhosis in children is a rare disease with multifactorial causes that are distinct from those in adults. Underlying reasons include cholestatic, viral, autoimmune, hereditary, metabolic and cardiac disorders. Early detection of fibrosis is important as clinical stabilization or even reversal of fibrosis can be achieved in some disorders with adequate treatment. This article focuses on the longitudinal evaluation of children with chronic liver disease with noninvasive imaging tools, which play an important role in detecting cirrhosis, defining underlying causes, grading fibrosis and monitoring patients during follow-up. Ultrasound is the primary imaging modality and it is used in a multiparametric fashion. Magnetic resonance imaging and computed tomography are usually applied second line for refined tissue characterization, clarification of nodular lesions and full delineation of abdominal vessels, including portosystemic communications.

Noninvasive imaging biomarkers for liver fibrosis in nonalcoholic fatty liver disease: current and future

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent worldwide and becoming a major cause of liver disease-related morbidity and mortality. The presence of liver fibrosis in patients with NAFLD is closely related to prognosis, including the development of hepatocellular carcinoma and other complications of cirrhosis. Therefore, assessment of the presence of significant or advanced liver fibrosis is crucial. Although liver biopsy has been considered the "gold standard" method for evaluating the degree of liver fibrosis, it is not suitable for extensive use in all patients with NAFLD owing to its invasiveness and high cost. Therefore, noninvasive biochemical and imaging biomarkers have been developed to overcome the limitations of liver biopsy. Imaging biomarkers for the stratification of liver fibrosis have been evaluated in patients with NAFLD using different imaging techniques, such as transient elastography, shear wave elastography, and magnetic resonance elastography. Furthermore, artificial intelligence and deep learning methods are increasingly being applied to improve the diagnostic accuracy of imaging techniques and overcome the pitfalls of existing imaging biomarkers. In this review, we describe the usefulness and future prospects of noninvasive imaging biomarkers that have been studied and used to evaluate the degree of liver fibrosis in patients with NAFLD.

Staging Liver Fibrosis by Fibroblast Activation Protein Inhibitor PET in a Human-Sized Swine Model

Current methods of staging liver fibrosis have notable limitations. We investigated the utility of PET in staging liver fibrosis by correlating liver uptake of ⁶⁸Ga-labeled fibroblast activation protein inhibitor (FAPI) with histology in a human-sized swine model. Methods: Five pigs underwent baseline ⁶⁸Ga-FAPI-46 (⁶⁸Ga-FAPI) PET/MRI and liver biopsy, followed by liver parenchymal embolization, 8 wk of oral alcohol intake, endpoint ⁶⁸Ga-FAPI PET/MRI, and necropsy. Regions of interest were drawn on baseline and endpoint PET images, and SUV_mean was recorded. At the endpoint, liver sections corresponding to regions of interest were identified and cut out. Fibrosis was histologically evaluated using a modified METAVIR score for swine liver and quantitatively using collagen proportionate area (CPA). Box-and-whisker plots and linear regression were used to correlate SUV_mean with METAVIR score and CPA, respectively. Results: Liver ⁶⁸Ga-FAPI uptake strongly correlated with CPA (r = 0.89, P < 0.001). ⁶⁸Ga-FAPI uptake was significantly and progressively higher across F2 and F3/F4 fibrosis stages, with a respective median SUV_mean of 2.9 (interquartile range [IQR], 2.7-3.8) and 7.6 (IQR, 6.7-10.2) (P < 0.001). There was no significant difference between ⁶⁸Ga-FAPI uptake of baseline liver and endpoint liver sections staged as F0/F1, with a respective median SUV_mean of 1.7 (IQR, 1.3-2.0) and 1.7 (IQR, 1.5-1.8) (P = 0.338). Conclusion: The strong correlation between liver ⁶⁸Ga-FAPI uptake and the histologic stage of liver fibrosis suggests that ⁶⁸Ga-FAPI PET can play an impactful role in noninvasive staging of liver fibrosis, pending validation in patients.

Magnetic resonance elastography: from invention to standard of care

In 1995, a vivid image of diffracting waves in red and blue was published on the cover of the journal SCIENCE. An article in that issue described a new imaging technology called magnetic resonance elastography (MRE) (Muthupillai in Science 269:1854-1857, 1995). In 2004, quantitative images of liver stiffness in vivo, obtained with MRE, were demonstrated for the first time at the annual meeting of the International Society for Magnetic Resonance in Medicine. Only five years later, the technology had become widely available as an FDA-cleared diagnostic tool for patient care. MRE has emerged as a reliable non-invasive diagnostic method for detecting and staging liver fibrosis. Deployed on more than 2000 MRI systems worldwide, MRE has received a Category I CPT code from the American Medical Association, based on clinical availability and efficacy. For many patients, MRE now provides a safe, more comfortable, and much less expensive alternative to liver biopsy for diagnosing liver fibrosis. Although progress in radiology is notable for a history of very rapid translation of technology innovations to patient care, the path is rarely linear. This article reflects on the story of MRE, the advances and the setbacks, and the lessons that were learned in the process.

Noninvasive staging of liver fibrosis: review of current quantitative CT and MRI-based techniques

Liver fibrosis features excessive protein accumulation in the liver interstitial space resulting from repeated tissue injury due to chronic liver disease. Liver fibrosis eventually proceeds to cirrhosis and associated complications. So, early diagnosis and staging of liver fibrosis are of vital importance for clinical treatment. Liver biopsy remains the gold standard for the diagnosing and staging of fibrosis, but it is suboptimal due to various limitations. Recently, efforts have been made to migrate toward noninvasive techniques for assessing liver fibrosis. CT is relatively easy to perform, relatively standardized for different scanners, and does not require additional hardware in liver fibrosis staging. MRI is frequently performed to characterize indeterminate liver lesions. Because it does not use ionizing radiation and features high image contrast, its role has increased in the staging of liver fibrosis. More recently, several studies on liver fibrosis staging using deep learning algorithms in CT or MRI have been proposed and have shown meaningful results. In this review, we summarize the basic concept, diagnostic performance, and advantages and limitations of each technique to noninvasively stage liver fibrosis.

Comparing shear wave elastography with liver biopsy in the assessment of liver fibrosis at King Hussein Medical Center

Background and study aims

The aim of this prospective study is to compare the sensitivity and specificity of the liver shear wave elastography to the golden standard liver biopsy in staging liver fibrosis.

Patients and methods

Ninety-five patients were included in this study. These patients were sent for liver biopsy as a possible living liver donor or because of different pathologies including viral and autoimmune hepatitis and congenital liver diseases. A shear wave elastography and US-guided liver biopsy were done at the same setting by one experienced radiologist. One experienced histopathologist, blinded to SWE results, read the specimens.

Results

We included 95 patients in the study with a mean age of 30 years (range 3–65 years). We had 15/95 (16%) patients with hepatitis B/C, 61/95 (64%) patients with another liver disease, and 19/95 (20%) were donors. The mean of liver stiffness measured by elastography in patients was 6.5±0.19 kPa. The mean liver stiffness measured by elastography in patients with F0–F1 fibrosis was 5.39 ± 0.62 kPa, F2 was 7.32 ± 0.41, at stage F3 was 8.46 ± 0.33, and in the F4 stage, it was 11.42 ± 2.8 kPa. We found a significant difference in the mean level of liver stiffness in different degrees of fibrosis (p = 0.0001).

Conclusion

The shear wave elastography could be used to assess liver fibrosis regardless of the cause.

Liver fibrosis quantification

Liver fibrosis (LF) is the wound healing response to chronic liver injury. LF is the endpoint of chronic liver disease (CLD) regardless of etiology and the single most important determinant of long-term liver-related clinical outcomes. Quantification of LF is important for staging, to evaluate response to treatment and to predict outcomes. LF is traditionally staged by liver biopsy. However, liver biopsy is invasive and suffers from sampling errors when biopsy size is inadequate; therefore, non-invasive tests (NITs) have found important roles in clinical care. NITs include simple laboratory-based serum tests, panels of serum tests, and imaging biomarkers. NITs are validated against the liver biopsy and will be used in the future for evaluation of nearly all CLDs with invasive liver biopsy reserved for some cases. Both serum tests and some imaging biomarkers such as elastography are currently used clinically as surrogate markers for LF. Several other imaging biomarkers are still considered research and awaiting clinical application in the future. As the evaluation of imaging biomarkers will likely become the norm in the future, understanding pathogenesis of LF is important. Knowledge of properties measured by imaging biomarkers and its correlation with LF is important to understand the application of NITs by abdominal radiologists. In this review, we present a brief overview of pathogenesis of LF, spatiotemporal evolution of LF in different CLD, and severity assessment with liver biopsy. This will be followed by a brief discussion on properties measured by imaging biomarkers and their relationship to the LF.

A proposed model on MR elastography for predicting postoperative major complications in patients with hepatocellular carcinoma

Objective

To develop a model for predicting post-operative major complications in patients with hepatocellular carcinoma (HCC).

Methods

In all, 186 consecutive patients with pre-operative MR elastography were included. Complications were categorised using Clavien‒Dindo classification, with major complications defined as ≥Grade 3. Liver-stiffness measurement (LSM) values were measured on elastogram. The indocyanine green clearance rate of liver remnant (ICG-Krem) was based on the results of CT volumetry, intraoperative data, and ICG-K value. For an easy application to the prediction model, the continuous variables were converted to categories. Moreover, logistic regression analysis and fivefold cross-validation were performed. The prediction model's discriminative performance was evaluated using the area under the receiver operating characteristic curve (AUC), and the calibration of the model was assessed by the Hosmer‒Lemeshow test.

Results

43 of 186 patients (23.1%) had major complications. The multivariate analysis demonstrated that LSM, albumin-bilirubin (ALBI) score, intraoperative blood loss, and ICG-Krem were significantly associated with major complications. The median AUC of the five validation subsets was 0.878. The Hosmer-Lemeshow test confirmed no evidence of inadequate fit (p = 0.13, 0.19, 0.59, 0.59, and 0.73) on the fivefold cross-validation. The prediction model for major complications was as follows: -2.876 + 2.912 [LSM (>5.3 kPa)]+1.538 [ALBI score (>-2.28)]+0.531 [Intraoperative blood loss (>860 ml)]+0.257 [ICG-Krem (<0.10)].

Conclusion

The proposed prediction model can be used to predict post-operative major complications in patients with HCC.

Advances in knowledge

The proposed prediction model can be used in routine clinical practice to identify post-operative major complications in patients with HCC and to strategise appropriate treatments of HCC.

Magnetic resonance quantification of non-Gaussian water diffusion in hepatic fibrosis staging: a pilot study of diffusion kurtosis imaging to identify reversible hepatic fibrosis

Background

This study aimed to evaluate the diagnostic accuracy of diffusion kurtosis imaging (DKI) in differentiating early hepatic fibrosis (HF) from normal liver and advanced HF in rabbits.

Methods

A total of 35 healthy New Zealand white rabbits were included in the study. A model of HF was established in 30 rabbits through subcutaneous injections of 50% carbon tetrachloride (CCl₄)/olive oil, while 5 rabbits received saline injections. The gradually increased doses of CCl₄ were 0.1, 0.2, and 0.3 mL/kg in weeks 1 to 3, weeks 4 to 6, and weeks 7 to 10, respectively. Two injections were given each week. Two rabbits in the experimental group died. All rabbits underwent DKI with three b values (0, 500, and 1,000 s/mm²) at week 5 (n=8), week 6 (n=9), week 7 (n=8), and week 10 (n=8). Approximately 2 liver lobes per rabbit were selected for histopathology. Mean diffusivity (MD) and mean kurtosis (MK) were calculated. Discrimination capacities of DKI parameters were analyzed and compared by receiver operating characteristic (ROC) analysis.

Results

The meta-analysis of histological data in viral hepatitis (METAVIR) scoring system was used to classify liver lobes into the control group (F0, n=0), early HF group (F1-F2, n=28), and advanced HF group (F3-F4, n=28). MD and MK values were significantly different among the three groups (all P<0.05). MD value was negatively correlated with increased fibrosis level, while MK value was positively correlated with increased fibrosis level (ρ=-0.540, 0.614; P<0.05). The area under ROC curves (AUCs) for MD and MK were 0.886 and 0.875, respectively, for characterization of F0 and F1-F2, and 0.975 and 0.957 for F0 and F3-F4. AUC for MK was 0.751 for characterization of F1-F2 and F3-F4. MD performed better than MK for characterization of F0 and F1-F2 as well as F0 and F3-F4. MK showed good differentiation performance between F1-F2 and F3-F4.

Conclusions

Our results showed that DKI contributed to discriminating reversible early HF from normal liver and advanced HF and as a result, showed promise for use in HF diagnosis.

Quality Control of Magnetic Resonance Elastography Using Percent Measurable Liver Volume Estimation

BACKGROUND

Although studies have described factors associated with failed magnetic resonance elastography (MRE), little is known about what factors influence usable elastography data.

PURPOSE

To identify factors that have a negative impact on percent measurable liver volume (pMLV), defined as the proportion of usable liver elastography data relative to the volume of imaged liver in patients undergoing MRE.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 264 patients (n = 132 males, n = 132 females; mean age = 57 years) with suspected or known chronic liver disease underwent MRE paired with a liver protocol MRI.

FIELD STRENGTH/SEQUENCE

MRE was performed on a single 1.5 T scanner using a two-dimensional gradient-recalled echo phase-contrast sequence with a passive acoustic driver overlying the right hemiliver.

ASSESSMENT

Stiffness maps (usable data at 95% confidence) and liver contours on magnitude images of the MRE acquisition were manually traced and used to assess mean stiffness and pMLV. Hepatic fat fraction and R² * values were also calculated. The distance from the acoustic wave generator on the skin surface to the liver edge was measured. Two radiologists performed the MR analyses with 50 overlapping cases for inter-reader analysis.

STATISTICAL TESTS

Linear regression was performed to identify factors significantly associated with pMLV. Intraclass correlation was performed for inter-reader reliability.

RESULTS

pMLV was 31% ± 20% (range 0%-86%). Complete MRE failure (i.e. pMLV = 0%) occurred in 10 patients (4%). Multivariate linear regression identified higher hepatic fat fraction, R² *, BMI, and driver-to-liver surface distance; male sex; and lower mean liver stiffness was significantly independently associated with lower pMLV. Intraclass correlation for pMLV was 0.96, suggestive of excellent reliability.

DATA CONCLUSION

Higher fat fraction, R² *, BMI, driver-to-liver surface distance, male sex, and lower mean liver stiffness were associated with lower pMLV. Optimization of image acquisition parameters and driver placement may improve MRE quality, and pMLV likely serves as a diagnostic utility quality control metric.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

Evaluation of Rabbits Liver Fibrosis Using Gd-DTPA-BMA of Dynamic Contrast-Enhanced Magnetic Resonance Imaging

Objective

To evaluate the different pharmacokinetic parameters of the DCE-MRI method on diagnosing and staging of rabbits' liver fibrosis.

Methods

We had performed DCE-MRI for rabbits that had been divided into the experiment group and the control group. Then, rabbits' images were transferred to a work station to get three parameters such as K _trans, K _ep, and V _e, which had been measured to calculate. After data were analyzed, ROC analyses were performed to assess the diagnostic performance of K _trans, K _ep, and V _e to judge liver fibrosis.

Results

The distribution of the different liver fibrosis group was as follows: F1, n = 8; F2, n = 9; F3, n = 6; F4, n = 5. No fibrosis was deemed as F0, n = 6. K _ep is statistically significant (P < 0.05) for F0 and mild liver fibrosis stage, and the K _ep shows AUC of 0.814. Three parameters are statistically significant for F0 and advanced liver fibrosis stage (K _trans and K _ep, P < 0.01; V _e, P < 0.05), and the K _trans shows AUC of 0.924; the K _ep shows AUC of 0.909; the V _e shows AUC of 0.848; K _trans and K _ep are statistically significant for mild and advanced liver fibrosis stages (K _trans, P < 0.01; K _ep, P < 0.05), and the K _trans shows AUC of 0.840; the K _ep shows AUC of 0.765. Both K _trans and K _ep are negatively correlated with the liver fibrosis stage. V _e is positively correlated with the liver fibrosis stage.

Conclusion

K _trans is shown to be the best DCE parameter to distinguish the fibrotic liver from the normal liver and mild and advanced fibrosis. On the contrary, K _ep is moderate and V _e is worst. And K _ep is a good DCE parameter to differentiate mild fibrosis from the normal liver.

Comparison of diffusion-weighted imaging and MR elastography in staging liver fibrosis: a meta-analysis

PURPOSE

To compare the diagnostic performance of diffusion-weighted imaging (DWI), gradient-recalled echo-based magnetic resonance elastography (GRE-MRE), and spin-echo echo-planar imaging-based MRE (SE-EPI-MRE) in liver fibrosis staging.

METHODS

A systematic literature search was done to collect studies on the performance of DWI, GRE-MRE, and SE-EPI-MRE for diagnosing liver fibrosis. Pooled sensitivity, specificity, diagnostic odds ratio, positive and negative likelihood ratio, and a summary receiver operating characteristic (ROC) curve were estimated with a bivariate random effects model. Subgroup analyses on various study characteristics were performed.

RESULTS

Sixty studies with a total of 6620 patients were included in the meta-analysis. Pooled sensitivity and specificity of GRE-MRE and SE-EPI-MRE showed high diagnostic accuracy and did not differ significantly. The area under the summary ROC curve for all stages of fibrosis differed significantly between DWI (0.83-0.88) and either GRE-MRE (0.95-0.97) or SE-EPI-MRE (0.95-0.99). Substantial heterogeneity was detected for all three imaging methods.

CONCLUSIONS

Both GRE-MRE and SE-EPI-MRE are highly accurate for detection of each liver fibrosis stage, with high potential to replace liver biopsy. Although DWI had a moderate accuracy in distinguishing liver fibrosis, it could be regarded as an alternative to MRE, since it is widely available and easily implemented in routine liver MRI.

Predictive value of combined computed tomography volumetry and magnetic resonance elastography for major complications after liver resection

PURPOSE

To retrospectively compare the predictive value of computed tomography volumetry (CTV), magnetic resonance elastography (MRE) of the liver, and their combination for major complications after liver resection.

METHODS

We enrolled 108 consecutive patients who underwent anatomical liver resection for liver tumors and preoperative contrast-enhanced CT and MRE. The future liver remnant (FLR) ratio was calculated by CTV, while the liver stiffness measurement (LSM) was obtained by MRE. FLR ratio alone, LSM alone, and combined FLR ratio and LSM were evaluated to predict major complications (Clavien-Dindo grade ≥ IIIa). Univariate and multivariate analyses of hepatic biochemical parameters and imaging data were performed to identify predictors of major complications. Receiver operating characteristic analyses of FLR ratio, LSM, and their combination were performed, and the sensitivity and specificity were calculated.

RESULTS

Twenty-two (20.4%) of the 108 patients experienced major complications. According to multiple regression analysis, the FLR ratio (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.91-0.99, p = 0.040) and LSM (OR 1.72, 95% CI 1.01-2.94, p = 0.047) were independent predictors of major complications. The combined FLR ratio and LSM were predictive of major complications, with an area under the curve (AUC) of 0.818, sensitivity of 68.2%, and specificity of 84.9%. The AUC and specificity for combined FLR ratio and LSM were larger than those for FLR ratio (AUC: 0.711, specificity: 80.2%) and LSM (AUC: 0.793, specificity: 80.2%).

CONCLUSION

Combined CTV and MRE analysis can improve the AUC and specificity for predicting major complications after anatomical liver resection.

Effect of hepatic steatosis on native T1 mapping of 3T magnetic resonance imaging in the assessment of T1 values for patients with non-alcoholic fatty liver disease

PURPOSE

This study investigated whether T1 values in native T1 mapping of 3T magnetic resonance imaging (MRI) of the liver were affected by the fatty component.

METHODS

This prospective study involved 340 participants from a population-based cohort study between May 8, 2018 and August 8, 2019. Data obtained included: (1) hepatic stiffness according to magnetic resonance elastography (MRE); (2) T1 value according to T1 mapping; (3) fat fraction and iron concentration from multi-echo Dixon; and (4) clinical indices of hepatic steatosis including body mass index, waist circumference, history of diabetes, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, and triglycerides. The correlations between T1 value and fat fraction, and between T1 value and liver stiffness were assessed using Pearson's correlation coefficient. The independent two-sample t-test was used to evaluate the differences in T1 values according to the presence or absence of hepatic steatosis, and the one-way analysis of variance was used to evaluate the difference in T1 value by grading of hepatic steatosis according to MRI-based proton density fat fraction (PDFF). In addition, univariate and multivariate linear regression analyses were performed to determine whether other variables influenced the T1 value.

RESULTS

T1 value showed a positive correlation with the fat fraction obtained from PDFF (r = 0.615, P < 0.001) and with the liver stiffness obtained from MRE (r = 0.370, P < 0.001). Regardless of the evaluation method, the T1 value was significantly increased in subjects with hepatic steatosis (P < 0.001). When comparing hepatic steatosis grades based on MRI-PDFF, the mean T1 values were significantly different in all grades, and the T1 value tended to increase as the grade increased (P < 0.001, P for trend <0.001). On multiple linear regression analysis, the T1 value was influenced by MRI-PDFF, calculated liver iron concentration, liver stiffness, and serum aspartate aminotransferase level.

CONCLUSION

The T1 value obtained by current T1 mapping of 3T MRI was affected by the liver fat component and several other factors such as liver stiffness, iron concentration, and inflammation.

Prevalence of liver fibrosis and associated risk factors in the Korean general population: a retrospective cross-sectional study

OBJECTIVES

The health burden of chronic liver disease is increasing worldwide. Its main histological consequence is liver fibrosis, and eventually cirrhosis. This process is rarely diagnosed at the pre-cirrhotic stage due to it being asymptomatic. Little is known about the prevalence of liver fibrosis and associated risk factors in the general population. The aims of this study were to determine the prevalence and distribution of liver fibrosis using magnetic resonance elastography (MRE), as well as the risk factors associated with liver fibrosis in the asymptomatic general population.

DESIGN, SETTING AND PARTICIPANTS

This cross-sectional retrospective study consecutively selected subjects who underwent health check-ups including MRE at 13 health promotion centres in Korea between 2018 and 2020. Liver fibrosis was estimated using MRE with cut-off values for significant and advanced liver fibrosis of 2.90 and 3.60 kPa, respectively.

PRIMARY AND SECONDARY OUTCOME MEASURES

The Χ² test was used to compare the prevalence of liver fibrosis according to sex and age groups. Multivariable logistic regression analyses were performed to identify the factors for significant and advanced liver fibrosis.

RESULTS

Among the 8183 subjects, 778 (9.5%) had ≥significant fibrosis (≥2.9 kPa), which included 214 (2.6%) subjects with ≥advanced fibrosis (≥3.6 kPa). Multivariable analysis revealed that liver fibrosis was associated with age (OR=1.34, 95% CI=1.18 to 1.51), male sex (OR=3.18, 95% CI=1.97 to 5.13), diabetes (OR=2.43, 95% CI=1.8 to 3.28), HBsAg positivity (OR=3.49, 95% CI=2.55 to 4.79), abnormal liver function test (OR=1.9, 95% CI=1.49 to 2.42) and obesity (OR=1.77, 95% CI=1.35 to 2.32) (all p<0.001), as well as metabolic syndrome (OR=1.4, 95% CI=1.05 to 1.87) (p=0.024).

CONCLUSIONS

The prevalence of significant or more liver fibrosis was high in the Korean general population and much higher among individuals with risk factors. This suggests that screening of liver fibrosis should be considered in general population, especially among high-risk groups.

Use of Texture Analysis on Noncontrast MRI in Classification of Early Stage of Liver Fibrosis

Purpose. To compare the diagnostic value of texture analysis- (TA-) derived parameters from out-of-phase T1W, in-phase T1W, and T2W images in the classification of the early stage of liver fibrosis. Methods. Patients clinically diagnosed with hepatitis B infection, who underwent liver biopsy and noncontrast MRI scans, were enrolled. TA parameters were extracted from out-of-phase T1-weighted (T1W), in-phase T1W, and T2-weighted (T2W) images and calculated using Artificial Intelligent Kit (AK). Features were extracted including first-order, shape, gray-level cooccurrence matrix, gray-level run-length matrix, neighboring gray one tone difference matrix, and gray-level differential matrix. After statistical analyses, final diagnostic models were constructed. Receiver operating curves (ROCs) and areas under the ROC (AUCs) were used to assess the diagnostic value of each final model and 100-time repeated cross-validation was applied to assess the stability of the logistic regression models. Results. A total of 57 patients were enrolled in this study, with 27 in the fibrosis stage < 2 and 30 in stages ≥ 2. Overall, 851 features were extracted per ROI. Eight features with high correlation were selected by the maximum relevance method in each sequence, and all had a good diagnostic performance. ROC analysis of the final models showed that all sequences had a preferable performance with AUCs of 0.87, 0.90, and 0.96 in T2W and in-phase and out-of-phase T1W, respectively. Cross-validation results reported the following values of mean accuracy, specificity, and sensitivity: 0.98 each for out-of-phase T1W; 0.90, 0.89, and 0.90 for in-phase T1W; and 0.86, 0.88, 0.84 for T2W in the training set, and 0.76, 0.81, and 0.72 for out-of-phase T1W; 0.74, 0.72, and 0.75 for in-phase T1W; and 0.63, 0.64, and 0.63 for T2W for the test group, respectively. Conclusion. Noncontrast MRI scans with texture analysis are viable for classifying the early stages of liver fibrosis, exhibiting excellent diagnostic performance.

Imaging Biomarkers of Hepatic Fibrosis: Reliability and Accuracy of Hepatic Periportal Space Widening and Other Morphologic Features on MRI

OBJECTIVE. The purpose of this article was to assess the reliability and accuracy of hepatic periportal space widening and other qualitative imaging features for the prediction of hepatic fibrosis. MATERIALS AND METHODS. This single-center retrospective study identified consecutive patients who had undergone liver MR elastography. Two abdominal radiologists independently reviewed anatomic images, assessing multiple qualitative features of chronic liver disease (CLD) including periportal space widening. Each reader also measured the periportal space at the main portal vein (MPV) and right portal vein (RPV). Interrater reliability analysis was then performed. Sensitivity and specificity were determined for the detection of any hepatic fibrosis (stage I or higher) and of advanced fibrosis (stage III or higher) using stiffness on MR elastography as the reference standard. RESULTS. Of 229 subjects, 157 (69%) had fibrosis and 78 (34%) had advanced fibrosis. Agreement for periportal space widening was moderate (κ = 0.47), and agreement for remaining features was moderate to substantial (κ = 0.42-0.80). Agreement for the periportal space at the MPV was moderate (ICC, 0.55), and agreement for the periportal space at the RPV was near perfect (ICC, 0.83). Periportal space widening had the highest sensitivity (83.0%) for any fibrosis, with limited specificity (61.3%). Surface nodularity had the highest specificity (94.4%) for any fibrosis, with limited sensitivity (51.6%). Periportal space widening plus one or more additional imaging feature of CLD or the presence of surface nodularity alone had sensitivity of 72.6% and specificity of 76.1%. A periportal space at the MPV greater than 9.5 mm had substantial agreement with qualitative periportal space widening (κ = 0.74). CONCLUSION. Periportal space widening has a high sensitivity for hepatic fibrosis, with moderate specificity when combined with additional anatomic features of CLD.

Diffusion-weighted magnetic resonance imaging for the assessment of liver fibrosis in chronic viral hepatitis

Background

Accurate noninvasive methods for the assessment of liver fibrosis are urgently needed. This prospective study evaluated the diagnostic accuracy of diffusion-weighted magnetic resonance imaging (DWI) for the staging of liver fibrosis and proposed a diagnostic algorithm using DWI to identify cirrhosis in patients with chronic viral hepatitis.

Methods

One hundred twenty-one treatment-naïve patients with chronic hepatitis B or C were evaluated with DWI followed by liver biopsy on the same day. Breath-hold single-shot echo-planar DWI was performed to measure the apparent diffusion coefficient (ADC) of the liver and spleen. Normalized liver ADC was calculated as the ratio of liver ADC to spleen ADC.

Results

There was an inverse correlation between fibrosis stage and normalized liver ADC (p<0.05). For the prediction of fibrosis stage ≥2, stage ≥3, and cirrhosis, the area under the receiver-operating curve of normalized liver ADC was 0.603, 0.704, and 0.847, respectively. The normalized liver ADC value ≤1.02×10⁻³ mm²/s had 88% sensitivity, 81% specificity, 25% positive predictive value (PPV), and 99% negative predictive value (NPV) for the diagnosis of cirrhosis. Using a sequential approach with the Fibrosis-4 index followed by DWI, normalized liver ADC ≤1.02×10⁻³ mm²/s in patients with Fibrosis-4 >3.25 yielded an 80% PPV for cirrhosis, and a 100% NPV to exclude cirrhosis in patients with Fibrosis-4 between 1.45 and 3.25. Only 15.7% of patients would require a liver biopsy. This sequential strategy can reduce DWI examinations by 53.7%.

Conclusion

Normalized liver ADC measurement on DWI is an accurate and noninvasive tool for the diagnosis of cirrhosis in patients with chronic viral hepatitis.

Quantitative magnetic resonance imaging for chronic liver disease

Chronic liver disease (CLD) has rapidly increased in prevalence over the past two decades, resulting in significant morbidity and mortality worldwide. Historically, the clinical gold standard for diagnosis, assessment of severity, and longitudinal monitoring of CLD has been liver biopsy with histological analysis, but this approach has limitations that may make it suboptimal for clinical and research settings. Magnetic resonance (MR)-based biomarkers can overcome the limitations by allowing accurate, precise, and quantitative assessment of key components of CLD without the risk of invasive procedures. This review briefly describes the limitations associated with liver biopsy and the need for non-invasive biomarkers. It then discusses the current state-of-the-art for MRI-based biomarkers of liver iron, fat, and fibrosis, and inflammation.

Utility of Multiparametric CT for Identification of High-Risk NAFLD

OBJECTIVE. The purpose of this study was to evaluate the utility of laboratory and CT metrics in identifying patients with high-risk nonalcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS. Patients with biopsy-proven NAFLD who underwent CT within 1 year of biopsy were included. Histopathologic review was performed by an experienced gastrointestinal pathologist to determine steatosis, inflammation, and fibrosis. The presence of any lobular inflammation and hepatocyte ballooning was categorized as nonalcoholic steatohepatitis (NASH). Patients with NAFLD and advanced fibrosis (stage F3 or higher) were categorized as having high-risk NAFLD. Aspartate transaminase to platelet ratio index and Fibrosis-4 (FIB-4) laboratory scores were calculated. CT metrics included hepatic attenuation, liver segmental volume ratio (LSVR), splenic volume, liver surface nodularity score, and selected texture features. In addition, two readers subjectively assessed the presence of NASH (present or not present) and fibrosis (stages F0-F4). RESULTS. A total of 186 patients with NAFLD (mean age, 49 years; 74 men and 112 women) were included. Of these, 87 (47%) had NASH and 112 (60%) had moderate to severe steatosis. A total of 51 patients were classified as fibrosis stage F0, 42 as F1, 23 as F2, 37 as F3, and 33 as F4. Additionally, 70 (38%) had advanced fibrosis (stage F3 or F4) and were considered to have high-risk NAFLD. FIB-4 score correlated with fibrosis (ROC AUC of 0.75 for identifying high-risk NAFLD). Of the individual CT parameters, LSVR and splenic volume performed best (AUC of 0.69 for both for detecting high-risk NAFLD). Subjective reader assessment performed best among all parameters (AUCs of 0.78 for reader 1 and 0.79 for reader 2 for detecting high-risk NAFLD). FIB-4 and subjective scores were complementary (combined AUC of 0.82 for detecting high-risk NAFLD). For NASH assessment, FIB-4 performed best (AUC of 0.68), whereas the AUCs were less than 0.60 for all individual CT features and subjective assessments. CONCLUSION. FIB-4 and multiple CT findings can identify patients with high-risk NAFLD (advanced fibrosis or cirrhosis). However, the presence of NASH is elusive on CT.

Elastography in the evaluation of liver allograft

Elastography is an established technique in the evaluation of chronic liver diseases. While there is a large clinical experience and data available regarding the performance of elastography in native liver, elastography experience with liver grafts is limited and still growing. Both ultrasound-based elastography techniques and MR Elastography (MRE) are useful in the assessment of liver fibrosis in liver transplants. Technical modifications for performing elastography will be required for optimum evaluation of the graft. In general, caution needs to be exercised regarding the use of elastography immediately following transplantation as post-operative changes, perioperative conditions/complications, inflammation, and rejection can cause increased stiffness in the graft. In the follow-up, detection of increased stiffness with elastography is useful for predicting development of fibrosis in the graft. Adjunctive MRI or ultrasound with Doppler also provides comprehensive evaluation of anatomy, vascular anastomosis and patency, biliary tree, and stiffness for fibrosis. In this review, we provide a brief overview of elastography techniques available followed by the literature review of elastography in the evaluation of grafts and illustration with clinical examples.

Association between liver diffusion-weighted imaging apparent diffusion coefficient values and other measures of liver disease in pediatric autoimmune liver disease patients

BACKGROUND

Multiple quantitative magnetic resonance imaging (MRI) methods have been described to noninvasively detect and characterize liver fibrosis, including diffusion-weighted imaging (DWI).

PURPOSE

To evaluate associations between liver MRI DWI apparent diffusion coefficient (ADC) values and clinical factors and other quantitative liver MRI metrics in pediatric patients with autoimmune liver disease (AILD).

MATERIALS AND METHODS

Fifty-seven research liver MRI examinations performed from January 2017 to August 2018 for pediatric AILD registry participants were evaluated. Liver DWI ADC values, liver and spleen stiffness (kPa), and iron-corrected T1 (cT1; Perspectum Diagnostics) were measured at four anatomic levels. Participant age, sex, and laboratory data (alanine aminotransferase [ALT], total bilirubin, alkaline phosphatase, gamma-glutamyl transferase [GGT]) were recorded. Spearman's rank-order correlation (rho) and multiple linear regression were used to evaluate the associations between liver ADC values and predictor variables.

RESULTS

Mean (SD) participant age was 14.8 (4.0) years, 45.6% (26/57) were girls. Mean liver DWI ADC value was 1.34 (0.14 × 10^-3) mm²/s. Liver ADC values showed weak to moderate correlations with liver stiffness (r = - 0.42, p = 0.001), spleen stiffness (r = - 0.34; p = 0.015), whole-liver mean cT1 (r = - 0.39; p = 0.007), ALT (r = - 0.50; p = 0.0001), and GGT (r = - 0.48; p = 0.0004). Multiple linear regression showed liver stiffness (p = 0.0009) and sex (p = 0.023) to be independent predictors of liver ADC values.

CONCLUSION

Liver DWI ADC values are significantly associated with liver and spleen stiffnesses, liver cT1, ALT, GGT, and participant sex, with liver stiffness and sex remaining significant at multivariable regression. Liver ADC ultimately may play a role in multi-parametric prediction of chronic liver disease/fibrosis severity.

Diffusion-weighted imaging and texture analysis: current role for diffuse liver disease

Multiparametric MRI represents the primary imaging modality to assess diffuse liver disease, both in a qualitative and in a quantitative manner. Diffusion-weighted imaging (DWI) is among the imaging techniques that can be used to assess fibrosis due to its unique capability to assess microstructural changes at the tissue level. DWI is based on water mobility patterns and has the potential to become a non-invasive and non-destructive virtual biopsy to assess diffuse liver disease, overcoming sampling bias errors due to its three-dimensional imaging capabilities. Parallel to DWI, another quantitative method called texture analysis may be used to assess early and advanced diffused liver disease through quantifying spatial relationships in a global and local level, applying to any type of digital imaging technique like MRI or CT. Initial results using texture analysis hold great promise. In the current paper, we will review the role of DWI and texture analysis using MR images in assessing diffuse liver disease.

Liver stiffness in magnetic resonance elastography is prognostic for sorafenib-treated advanced hepatocellular carcinoma

OBJECTIVE

We investigated whether liver stiffness (LS) quantified using magnetic resonance elastography (MRE) could predict the prognosis of advanced hepatocellular carcinoma (HCC) patients treated with sorafenib.

METHODS

We selected 50 sorafenib-treated advanced HCC patients who underwent MRE within 3 months before drug administration from a prospectively maintained cohort of chronic liver disease patients, according to the inclusion and exclusion criteria. Univariate and multivariate analyses were performed to evaluate the prognostic role of laboratory data, tumor characteristics, and MRE-assessed LS for overall survival (OS), progression-free survival (PFS), and significant liver injury (grade ≥ 3) after sorafenib administration.

RESULTS

High MRE-assessed LS either as continuous (per kPa, hazard ratio (HR) 1.54; 95% confidence interval (CI) 1.23-1.92, p < 0.001) or categorical (> 7.5 kPa, HR 4.06, 95% CI 1.40-11.79, p < 0.01) variable was significantly associated with poor OS along with higher serum alpha-fetoprotein (AFP, ≥ 400 ng/mL) and advanced tumor stage (modified Union for International Cancer Control (mUICC) IVb). Higher MRE-assessed LS was also significantly associated with the development of significant liver injury after sorafenib administration (per kPa, HR 1.62, 95% CI 1.21-2.17, p = 0.001; > 7.5 kPa, HR 10.11, 95% CI 2.41-42.46, p = 0.002). PFS analysis identified higher serum AFP (≥ 400 ng/mL) and advanced tumor stage (mUICC IVb) as significant risk factors for early disease progression, whereas LS was not associated with PFS CONCLUSION: Higher MRE-assessed LS is a potential biomarker for predicting poor OS and significant liver injury in advanced HCC patients treated with sorafenib.

KEY POINTS

• Higher pretreatment LS by MRE (> 7.5 kPa), higher AFP (≥ 400 ng/mL), and advanced tumor stage (mUICC IVb) were associated with poor OS in advanced HCC patients treated with sorafenib. • Higher pretreatment LS by MRE was associated with developing significant (grade ≥ 3) liver injury during sorafenib treatment, which required termination of the therapy. • Patients with high pretreatment LS by MRE should be monitored carefully for potential liver injury during sorafenib treatment.

Usefulness of Different Imaging Modalities in Evaluation of Patients with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are becoming some of the major health problems in well-developed countries, together with the increasing prevalence of obesity, metabolic syndrome, and all of their systemic complications. As the future prognoses are even more disturbing and point toward further increase in population affected with NAFLD/NASH, there is an urgent need for widely available and reliable diagnostic methods. Consensus on a non-invasive, accurate diagnostic modality for the use in ongoing clinical trials is also required, particularly considering a current lack of any registered drug for the treatment of NAFLD/NASH. The aim of this narrative review was to present current information on methods used to assess liver steatosis and fibrosis. There are several imaging modalities for the assessment of hepatic steatosis ranging from simple density analysis by computed tomography or conventional B-mode ultrasound to magnetic resonance spectroscopy (MRS), magnetic resonance imaging proton density fat fraction (MRI-PDFF) or controlled attenuation parameter (CAP). Fibrosis stage can be assessed by magnetic resonance elastography (MRE) or different ultrasound-based techniques: transient elastography (TE), shear-wave elastography (SWE) and acoustic radiation force impulse (ARFI). Although all of these methods have been validated against liver biopsy as the reference standard and provided good accuracy, the MRS and MRI-PDFF currently outperform other methods in terms of diagnosis of steatosis, and MRE in terms of evaluation of fibrosis.

Liver MRI with amide proton transfer imaging: feasibility and accuracy for the characterization of focal liver lesions

OBJECTIVE

To investigate the feasibility of using amide proton transfer (APT) magnetic resonance imaging (MRI) in the liver and to evaluate its ability to characterize focal liver lesions (FLLs).

METHODS

A total of 203 patients with suspected FLLs who underwent APT imaging at 3T were included. APT imaging was obtained using a single-slice turbo spin-echo sequence to include FLLs through five breath-holds, and its acquisition time was approximately 1 min. APT signals in the background liver and FLL were measured with magnetization transfer ratio asymmetry (MTR_asym) at 3.5 ppm. The technical success rate of APT imaging and the reasons for failure to obtain meaningful MTR_asym values were assessed. The Mann Whitney U test was used to compare MTR_asym values between different FLLs.

RESULTS

The technical success rate of APT imaging in the liver was 62.1% (126/203). The reasons for failure were a too large B₀ inhomogeneity (n = 43), significant respiratory motion (n = 12), and these two factors together (n = 22), respectively. Among 59 FLLs with analyzable APT images, MTR_asym values were compared between 27 patients with liver metastases and 23 patients with hepatocellular carcinomas (HCCs). The MTR_asym values of metastases were significantly higher than those of HCC (0.13 ± 2.15% vs. - 1.41 ± 3.68%, p = 0.027).

CONCLUSIONS

APT imaging could be an imaging biomarker for the differentiation of FLLs. However, further technical improvement is required before APT imaging can be clinically applied to liver MRI.

KEY POINTS

• Liver APT imaging was technically feasible, but with a relatively low success rate (62.1%). • Liver metastases showed higher APT values than hepatocellular carcinomas.

Differentiating mild and substantial hepatic fibrosis from healthy controls: a comparison of diffusion kurtosis imaging and conventional diffusion-weighted imaging

BACKGROUND

Early and accurate detection of liver fibrosis are important for clinical treatment.

PURPOSE

To compare the diagnostic accuracy of liver diffusion kurtosis imaging (DKI) and conventional diffusion-weighted imaging (cDWI) in differentiating patients with mild and substantial fibrosis from normal individuals.

MATERIAL AND METHODS

Twenty-seven healthy volunteers with no fibrosis (S0) and 45 patients with mild (S1) or substantial (S2) liver fibrosis underwent DWI with multiple b-values. Liver mean apparent diffusion (MD) and mean kurtosis (MK) values derived from DKI and apparent diffusion coefficient (ADC) derived from cDWI were measured and compared. Their discriminative abilities were analyzed and compared by receiver operating characteristic (ROC) curve analysis.

RESULTS

Significant differences in MD and ADC values were found between groups (P < 0.05). MD value was statistically different between S0 and S1 (P = 0.028) and S0 and S2 (P = 0.005). ADC value was statistically different between S0 and S2 (P = 0.012). MK value was similar between groups (P = 0.646). MD and ADC values significantly correlated with fibrosis stages (r_s = -0.668, -0.341; P < 0.01). MK values had no correlation with fibrosis stages (r_s = 0.180; P = 0.130). The area under ROC curves (AUC) for MD and ADC was 0.937 and 0.707 for characterization of S1-2 and 0.817 and 0.658 for S2, respectively. MD performed better than ADC for characterization of S1-2 and S2 (P < 0.05).

CONCLUSION

Differentiating patients with mild or substantial fibrosis from normal individuals is feasible using DKI, which performs better than cDWI.

Recent advances in non-invasive diagnosis and medical management of non-alcoholic fatty liver disease in adult

Background

Number of non-alcoholic fatty liver disease (NAFLD) cases is increasing over time due to alteration of food habit, increase incidence of metabolic syndrome, and lack of exercise. Liver biopsy is the test for diagnosis and staging of NAFLD, but nowadays several biochemical markers, scoring systems, and imaging studies are available to diagnose and stage NAFLD which is linked to end-stage liver disease, hepatocellular cancer, and elevated cardiovascular- and cancer-related morbidity and mortality. Therefore urgent diagnosis and management are required to avoid complications related to NAFLD. This review summarizes recent advances in diagnosis and medical management of non-alcoholic fatty liver disease.

Main text

Recently published studies from PubMed, Red Cross, Copernicus, and also various previous studies were reviewed. We have discussed various non-invasive methods for detection of non-alcoholic fatty liver disease, non-alcoholic steatohepatitis (NASH), and hepatic fibrosis. Non pharmacological therapies for NAFLD, indications, and approved medications for NAFLD and other commonly used non-approved medications have been discussed in this review article.

Conclusions

Multiple non-invasive tests are available for diagnosis of NAFLD, and its different stages however gold standard test is liver biopsy. NALFD without NASH and significant fibrosis is treated by lifestyle modifications which include moderate to vigorous exercise and diet modification. To improve hepatic steatosis, minimum of 3–5% of body weight loss is necessary, but > 7–10% weight reductions is required for histological improvement in NASH and fibrosis. Pharmacotherapy is indicated when patient is having NASH with significant fibrosis.

Biomarkers of liver fibrosis: prospective comparison of multimodal magnetic resonance, serum algorithms and transient elastography

BACKGROUND AND AIMS

Accurate biomarkers for quantifying liver fibrosis are important for clinical practice and trial end-points. We compared the diagnostic performance of magnetic resonance imaging (MRI), including gadoxetate-enhanced MRI and ³¹P-MR spectroscopy, with fibrosis stage and serum fibrosis algorithms in a clinical setting. Also, in a subset of patients, MR- and transient elastography (MRE and TE) was evaluated when available.

METHODS

Patients were recruited prospectively if they were scheduled to undergo liver biopsy on a clinical indication due to elevated liver enzyme levels without decompensated cirrhosis. Within a month of the clinical work-up, an MR-examination and liver needle biopsy were performed on the same day. Based on late-phase gadoxetate-enhanced MRI, a mathematical model calculated hepatobiliary function (relating to OATP1 and MRP2). The hepatocyte gadoxetate uptake rate (K_Hep) and the normalised liver-to-spleen contrast ratio (LSC_N10) were also calculated. Nine serum fibrosis algorithms were investigated (GUCI, King's Score, APRI, FIB-4, Lok-Index, NIKEI, NASH-CRN regression score, Forns' score, and NAFLD-fibrosis score).

RESULTS

The diagnostic performance (AUROC) for identification of significant fibrosis (F2-4) was 0.78, 0.80, 0.69, and 0.78 for MRE, TE, LSC_N10, and GUCI, respectively. For the identification of advanced fibrosis (F3-4), the AUROCs were 0.93, 0.84, 0.81, and 0.82 respectively.

CONCLUSION

MRE and TE were superior for non-invasive identification of significant fibrosis. Serum fibrosis algorithms developed for specific liver diseases are applicable in this cohort of diverse liver diseases aetiologies. Gadoxetate-MRI was sufficiently sensitive to detect the low function losses associated with fibrosis. None was able to efficiently distinguish between stages within the low fibrosis stages.Lay summaryExcessive accumulation of scar tissue, fibrosis, in the liver is an important aspect in chronic liver disease. To replace the invasive needle biopsy, we have explored non-invasive methods to assess liver fibrosis. In our study we found that elastographic methods, which assess the mechanical properties of the liver, are superior in assessing fibrosis in a clinical setting. Of interest from a clinical trial point-of-view, none of the tested methods was sufficiently accurate to distinguish between adjacent moderate fibrosis stages.

Advances in non-invasive assessment of hepatic fibrosis

Liver fibrosis should be assessed in all individuals with chronic liver disease as it predicts the risk of future liver-related morbidity and thus need for treatment, monitoring and surveillance. Non-invasive fibrosis tests (NITs) overcome many limitations of liver biopsy and are now routinely incorporated into specialist clinical practice. Simple serum-based tests (eg, Fibrosis Score 4, non-alcoholic fatty liver disease Fibrosis Score) consist of readily available biochemical surrogates and clinical risk factors for liver fibrosis (eg, age and sex). These have been extensively validated across a spectrum of chronic liver diseases, however, tend to be less accurate than more 'complex' serum tests, which incorporate direct measures of fibrogenesis or fibrolysis (eg, hyaluronic acid, N-terminal propeptide of type three collagen). Elastography methods quantify liver stiffness as a marker of fibrosis and are more accurate than simple serum NITs, however, suffer increasing rates of unreliability with increasing obesity. MR elastography appears more accurate than sonographic elastography and is not significantly impacted by obesity but is costly with limited availability. NITs are valuable for excluding advanced fibrosis or cirrhosis, however, are not sufficiently predictive when used in isolation. Combining serum and elastography techniques increases diagnostic accuracy and can be used as screening and confirmatory tests, respectively. Unfortunately, NITs have not yet been demonstrated to accurately reflect fibrosis change in response to treatment, limiting their role in disease monitoring. However, recent studies have demonstrated lipidomic, proteomic and gut microbiome profiles as well as microRNA signatures to be promising techniques for fibrosis assessment in the future.

Value of intravoxel incoherent motion in detecting and staging liver fibrosis: A meta-analysis

BACKGROUND

Liver fibrosis (LF) is a common pathological feature of all chronic liver diseases. With the accumulation of extracellular matrix in the fibrotic liver, true molecular water diffusion and perfusion-related diffusion are restricted. Intravoxel incoherent motion (IVIM) can capture the information on tissue diffusivity and microcapillary perfusion separately and reflect the fibrotic severity with diffusion coefficients.

AIM

To investigate the diagnostic performance of IVIM in detecting and staging LF with histology as a reference standard.

METHODS

A comprehensive literature search was conducted to identify studies on the diagnostic accuracy of IVIM for assessment of histologically proven LF. The stages of LF were classified as F0 (no fibrosis), F1 (portal fibrosis without septa), F2 (periportal fibrosis with few septa), F3 (septal fibrosis), and F4 (cirrhosis) according to histopathological findings. Data were extracted to calculate the pooled sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio, as well as the area under the summary receiver operating characteristic curve (AUC) in each group.

RESULTS

A total of 12 studies with 923 subjects were included in this meta-analysis with 5 studies (n = 465) for LF ≥ F1, 9 studies (n = 757) for LF ≥ F2, 4 studies (n = 413) for LF ≥ F3, and 6 studies (n = 562) for LF = F4. The pooled sensitivity and specificity were estimated to be 0.78 (95% confidence interval: 0.73-0.82) and 0.81 (0.74-0.86) for LF ≥ F1 detection with IVIM; 0.82 (0.79-0.86) and 0.80 (0.75-0.84) for staging F2 fibrosis; 0.85 (0.79-0.90) and 0.83 (0.77-0.87) for staging F3 fibrosis, and 0.90 (0.84-0.94) and 0.75 (0.70-0.79) for detecting F4 cirrhosis, respectively. The AUCs for LF ≥ F1, F2, F3, F4 detection were 0.862 (0.811-0.914), 0.883 (0.856-0.909), 0.886 (0.865-0.907), and 0.899 (0.866-0.932), respectively. Moderate to substantial heterogeneity was observed with inconsistency index (I²) ranging from 0% to 77.9%. No publication bias was detected.

CONCLUSION

IVIM is a noninvasive tool with good diagnostic performance in detecting and staging LF. Optimized and standardized IVIM protocols are needed to further improve its diagnostic accuracy in clinical practice.

M2BPGi for assessing liver fibrosis in patients with hepatitis C treated with direct-acting antivirals

BACKGROUND

Assessing liver fibrosis is important for predicting the efficacy of direct-acting antivirals (DAAs) and patient prognosis. Non-invasive techniques to assess liver fibrosis are becoming important. Recently, serum Mac-2 binding protein glycosylation isomer (M2BPGi) was identified as a non-invasive marker of liver fibrosis.

AIM

To investigate the diagnostic accuracy of M2BPGi in assessing liver fibrosis in patients with chronic hepatitis C (CHC) treated with DAAs.

METHODS

From December 2017 to August 2018, 80 treatment-naïve adult patients with CHC who were eligible for DAAs therapy were consecutively enrolled in this observational cohort study. For 12 weeks, 65 patients were treated with sofosbuvir/daclatasvir, and 15 patients were treated with sofosbuvir/daclatasvir and a weight-based dose of ribavirin at knowledge and technology association for hepatitis C management clinic, Cairo, Egypt. We measured serum M2BPGi levels, PAPAS index, fibrosis-4 (FIB-4) score and liver stiffness measurements (LSM) at baseline and 12 weeks after the end of treatment. Serum M2BPGi levels were measured using enzyme-linked immunosorbent assay.

RESULTS

All patients achieved sustained virologic response (SVR12) (100%). Serum M2BPGi levels, LSM, FIB-4 score and PAPAS index decreased significantly at SVR12 (P < 0.05). Serum M2BPGi levels correlated positively with LSM at baseline and SVR12 (P < 0.001). At baseline, compared with the FIB-4 score and PAPAS index, M2BPGi was the best marker to distinguish patients with grade F4 fibrosis (AUC = 0.801, P < 0.001), patients with grade F2 from grade F0-1 fibrosis (AUC = 0.713, P = 0.012), patients with grade F3-4 from grade F0-2 fibrosis (AUC = 0.730, P < 0.001), and patients with grade F2-4 from grade F0-1 fibrosis (AUC = 0.763, P < 0.001). At SVR12, M2BPGi had the greatest AUCs for differentiating patients with grade F4 fibrosis (AUC = 0.844, P < 0.001), patients with grade F3 from grade F0-2 fibrosis (AUC = 0.893, P = 0.002), patients with grade F3-4 from grade F0-2 fibrosis (AUC = 0.891, P < 0.001), and patients with grade F2-4 from grade F0-1 fibrosis (AUC = 0.750, P < 0.001).

CONCLUSION

M2BPGi is a reliable marker for the non-invasive assessment and prediction of liver fibrosis regression in patients with CHC who achieved an SVR with DAAs therapy.

Assessment of liver fibrosis with liver and spleen magnetic resonance elastography, serum markers in chronic liver disease

Background

The accurate assessment of liver fibrosis is essential for patients with chronic liver disease. A liver biopsy is an invasive procedure that has many potential defects and complications. Therefore, noninvasive assessment techniques are of considerable value for clinical diagnosis. Liver and spleen magnetic resonance elastography (MRE) and serum markers have been proposed for quantitative and noninvasive assessment of liver fibrosis. This study aims to compare the diagnostic performance of liver and spleen stiffness measured by MRE, fibrosis index based on the 4 factors (FIB-4), aspartate aminotransferase-to-platelet ratio index (APRI), and their combined models for staging hepatic fibrosis.

Methods

One hundred and twenty patients with chronic liver disease underwent MRE scans. Liver and spleen stiffness were measured by the MRE stiffness maps. Serum markers were collected to calculate FIB-4 and APRI. Liver biopsies were used to identify pathologic grading. Spearman's rank correlation analysis evaluated the correlation between the parameters and fibrosis stages. Receiver operating characteristic (ROC) analysis evaluated the performance of the four individual parameters, a liver and spleen stiffness combined model, and an all-parameters combined model in assessing liver fibrosis.

Results

Liver stiffness, spleen stiffness, FIB-4, and APRI were all correlated with fibrosis stage (r=0.87, 0.64, 0.65, and 0.51, respectively, all P<0.001). Among the 4 individual diagnostic markers, liver stiffness showed the highest values in staging F1-4, F2-4, F3-4 and F4 (AUC =0.89, 0. 97, 0.95, and 0.95, all P<0.001). The AUCs of the liver and spleen stiffness combined model in the F1-4, F2-4, F3-4, and F4 staging groups were 0.89, 0.97, 0.95, and 0.96, respectively (all P<0.001). The corresponding AUCs of the all-parameters combined model were 0.90, 0.97, 0.95, and 0.96 (all P<0.001). The AUCs of the liver and spleen stiffness combined model were significantly higher than those of APRI, FIB-4 in the F2-4, F3-4, and F4 staging groups (all P<0.05). Both combined models were not significantly different from liver stiffness in staging liver fibrosis (all P>0.05).

Conclusions

Liver stiffness measured with MRE had better diagnostic performance than spleen stiffness, APRI, and FIB-4 for fibrosis staging. The combined models did not significantly improve the diagnostic value compared with liver stiffness in staging fibrosis.

ACR Appropriateness Criteria® Chronic Liver Disease

The liver fibrosis stage is the most important clinical determinate of morbidity and mortality in patients with chronic liver diseases. With newer therapies, liver fibrosis can be stabilized and possibly reversed, thus accurate diagnosis and staging of liver fibrosis are clinically important. Ultrasound, CT, and conventional MRI can be used to establish the diagnosis of advanced fibrosis/cirrhosis but have limited utility for assessing earlier stages of fibrosis. Elastography-based ultrasound and MRI techniques are more useful for assessment of precirrhotic hepatic fibrosis. In patients with advanced fibrosis at risk for hepatocellular carcinoma (HCC), ultrasound is the surveillance modality recommended by international guidelines in nearly all circumstances. However, in patients in whom ultrasound does not assess the liver well, including those with severe steatosis or obesity, multiphase CT or MRI may have a role in surveillance for HCC. Both multiphase CT and MRI can be used for continued surveillance in patients with a history of HCC, and contrast-enhanced ultrasound may have an emerging role in this setting. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Non-invasive diagnosis of liver fibrosis: A review of current imaging modalities

Hundreds of millions of patients are suffering from cirrhosis and other chronic liver diseases worldwide, and this public health problem continues to grow. It has been proven that liver fibrosis is reversible after the elimination of the etiology, especially in the early stage. Thus, early diagnosis of liver fibrosis is of vital importance for clinical treatment. Liver biopsy remains the gold standard for both diagnosis and staging of fibrosis, but is suboptimal, due in large parts to its invasive nature and sundry associated complications. To overcome this, a number of non-invasive diagnosis based on serum biomarkers or imaging modalities have been developed. While diagnosis based on serum biomarkers is cheaper and more acceptable to patients, almost none developed to date are liver-specific, and may engender a false positive error. The imaging modalities have evolved rapidly and are taking on more and more important roles in the diagnosis of liver fibrosis.

Intravoxel incoherent motion imaging for diagnosing and staging the liver fibrosis and inflammation

PURPOSE

To evaluate the diagnostic accuracy of intravoxel incoherent motion (IVIM) model parameters for the diagnosis and staging of liver fibrosis and inflammation in patients with chronic hepatitis B.

METHODS

Fifty-four patients with chronic hepatitis B and 42 healthy volunteers were included in the study. All subjects were examined by 3 T magnetic resonance imaging. Diffusion-weighted imaging was undertaken with sixteen b values. IVIM parameters [D (true diffusion coefficient), D* (pseudo-diffusion coefficient), f (perfusion fraction)] were calculated. Histological evaluation of biopsy samples was considered the reference standard for the staging of liver fibrosis and inflammation. Differences in IVIM parameters between patient and control groups were analyzed. In the patient group, fibrosis stage and inflammation grade groups were analyzed with respect to IVIM parameters. The correlation was assessed between IVIM parameters and Ishak-modified scale of fibrosis stages and inflammation grades.

RESULTS

The D was significantly lower in the patient group than the control group, p = 0.038 with Cohen's d effect size of 0.452. D was significantly different between fibrosis stage levels. D values decreased in fibrosis stages from the minimal to moderate to marked fibrosis. Fibrosis grades significantly negatively correlated with D and D* values, p = 0.001, and 0.021, respectively. In addition, inflammation grades negatively correlated with f values, p = 0.047.

CONCLUSION

D values measured with IVIM imaging may help to diagnose liver fibrosis. IVIM imaging could be an alternative to liver biopsy for the staging of liver fibrosis.

Liver shape analysis using partial least squares regression-based statistical shape model: application for understanding and staging of liver fibrosis

PURPOSE

Liver shape variations have been considered as feasible indicators of liver fibrosis. However, current statistical shape models (SSM) based on principal component analysis represent gross shape variations without considering the association with the fibrosis stage. Therefore, we aimed at the application of a statistical shape modelling approach using partial least squares regression (PLSR), which explicitly uses the stage as supervised information, for understanding the shape variations associated with the stage as well as predicting it in contrast-enhanced MR images.

METHODS

Contrast-enhanced MR images of 51 patients with fibrosis stages F0/1 (n = 18), F2 (n = 15), F3 (n = 7) and F4 (n = 11) were used. The livers were manually segmented from the images. An SSM was constructed using PLSR, by which shape variation modes (scores) that were explicitly associated with the reference pathological fibrosis stage were derived. The stage was predicted using a support vector machine (SVM) based on the PLSR scores. The performance was assessed using the area under receiver operating characteristic curve (AUC).

RESULTS

In addition to commonly known shape variations, such as enlargement of left lobe and shrinkage of right lobe, our model represented detailed variations, such as enlargement of caudate lobe and the posterior part of right lobe, and shrinkage in the anterior part of right lobe. These variations qualitatively agreed with localized volumetric variations reported in clinical studies. The accuracy (AUC) at classifications F0/1 versus F2‒4 (significant fibrosis), F0‒2 versus F3‒4 and F0‒3 versus F4 (cirrhosis) were 0.90 ± 0.03, 0.80 ± 0.05 and 0.82 ± 0.05, respectively.

CONCLUSIONS

The proposed approach offered an explicit representation of commonly known as well as detailed shape variations associated with liver fibrosis stage. Thus, the application of PLSR-based SSM is feasible for understanding the shape variations associated with the liver fibrosis stage and predicting it.

Use of ultrasound combined with magnetic resonance imaging for diagnosis of breast masses and fibroids

Objective

To investigate the clinical value of ultrasound plus magnetic resonance imaging (MRI) for the diagnosis of breast masses and fibroids.

Methods

Clinical data for 357 patients with breast masses diagnosed at our hospital were analyzed retrospectively. The diagnostic performances were compared between 243 patients who underwent routine ultrasound examinations (control group) and 114 patients who underwent routine ultrasound plus MRI (test group).

Results

The overall accordance rates of routine ultrasound and routine ultrasound plus MRI for the diagnosis of breast masses, based on postoperative pathological diagnoses, were 70.78% (172/243) and 90.35% (103/114). The addition of MRI significantly improved the overall diagnostic performance of routine ultrasound for breast masses. The diagnostic accordance rate of routine ultrasound for the diagnosis of breast fibroids (fibroadenomas) was 74.12% (63/85 cases) compared with 93.94% (31/33 cases) for routine ultrasound plus MRI. The diagnostic performance of routine ultrasound plus MRI was therefore also significantly higher than routine ultrasound alone for diagnosing breast fibroids.

Conclusions

Routine ultrasound plus MRI can greatly improve the diagnostic accordance rates for breast masses and fibroadenomas.

Magnetic Resonance Diffusion Kurtosis Imaging for Evaluating Stage of Liver Fibrosis in a Rabbit Model

RATIONALE AND OBJECTIVES

As an extension of the conventional diffusion weighted imaging, diffusion kurtosis imaging (DKI) is based on the non-Gaussian diffusion model that can inherently account for restricted water diffusion within the complex microstructure of most tissues. This study aimed to investigate association of liver DKI derived parameter with stage of liver fibrosis.

MATERIALS AND METHODS

Fifty-six healthy New Zealand white rabbits were enrolled into this study, among which 48 rabbits were randomly given carbon tetrachloride to model liver fibrosis, and 8 rabbits treated with normal saline served as control subjects. All rabbits underwent liver DKI followed by biopsy to stage fibrosis (stages F0-F4) on 6th, 8th, 10th, and 12th weekends after initiation of modeling fibrosis. Mean kurtosis (MK), fractional anisotropy (FA), and mean diffusion (MD) were derived from DKI data. Statistical analysis was to evaluate association of DKI derived parameter with stage of fibrosis.

RESULTS

FA (r = 0.512) and MK (r = 0.567) increased, and MD (r = -0.574) decreased with increasing stage of fibrosis from F0 to F4 (all p values < 0.05). Significant differences were found in all parameters between F0 and F3 or F4, F1 and F4, F0 and F1-4, and F0-1 and F2-4 (all p values < 0.05). FA and MD could distinguish between F0 from F2, MD, and MK could distinguish F1 from F3, F0-2 from F3-4, and F1-2 from F3-4, and MK and FA could distinguish F2 from F4, and F0-3 from F4 (all p values < 0.05). According to receiver operating characteristic analysis, MK could best predict stage ≥F1, ≥F2, ≥F3, and F4, and discriminate F1-2 from F3-4 with areas under receiver operating characteristic curve of 0.766-0.930.

CONCLUSION

DKI derived parameters can help stage fibrosis.

Diagnostic value of MR-based texture analysis for the assessment of hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD)

PURPOSE

To investigate the performance of MR-based texture analysis (TA) for the assessment of hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

Fifty-four adult patients (33 females, 21 males, mean age 49.8 ± 13.5 years) with biopsy-proven NAFLD were enrolled and underwent MR imaging on a 1.5 T system. TA parameters were extracted on axial noncontrast 3D-GRE T1W images (slice thickness = 4.6 mm) using a commercially available research software (TexRAD). Receiver operating curves (ROC), areas under the ROC (AUROC) and 95% confidence intervals (CI) were calculated to assess the accuracy of each TA parameter for the diagnosis of significant (F ≥ 2) and advanced fibrosis (F ≥ 3). The correlation between TA and histopathological features of nonalcoholic steatohepatitis (NASH) was tested calculating the Spearman's rank correlation coefficient (ρ).

RESULTS

Thirty-seven (68%) subjects had significant fibrosis and 20 (37%) had advanced fibrosis. The TA parameters with the best performance were standard deviation (SD) and entropy, respectively, with AUROC 0.755 (95% CI 0.619-0.862, p ≤ 0.0002) and 0.769 (95% CI 0.634-0.873, p < 0.0001) for significant fibrosis and AUROC 0.746 (95% CI 0.609-0.854, p ≤ 0.0004) and 0.754 (95% CI 0.618-0.861, p ≤ 0.0002) for advanced fibrosis. SD and entropy demonstrated a moderate correlation with the degree of fibrosis (ρ = 0.457 and 0.480; p < 0.01). No significant correlation was found between TA parameters and other histopathological features of NASH.

CONCLUSIONS

Entropy and SD extracted on T1-weighted MR images have fair accuracy for the diagnosis of significant and advanced hepatic fibrosis in patients with NAFLD.

Noninvasive evaluation of nonalcoholic fatty liver disease: Current evidence and practice

With the increasing number of individuals with diabetes and obesity, nonalcoholic fatty liver disease (NAFLD) is becoming increasingly prevalent, affecting one-quarter of adults worldwide. The spectrum of NAFLD ranges from simple steatosis or nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH). NAFLD, especially NASH, may progress to fibrosis, leading to cirrhosis and hepatocellular carcinoma. NAFLD can impose a severe economic burden, and patients with NAFLD-related terminal or deteriorative liver diseases have become one of the main groups receiving liver transplantation. The increasing prevalence of NAFLD and the severe outcomes of NASH make it necessary to use effective methods to identify NAFLD. Although recognized as the gold standard, biopsy is limited by its sampling bias, poor acceptability, and severe complications, such as mortality, bleeding, and pain. Therefore, noninvasive methods are urgently needed to avoid biopsy for diagnosing NAFLD. This review discusses the current noninvasive methods for assessing NAFLD, including steatosis, NASH, and NAFLD-related fibrosis, and explores the advantages and disadvantages of measurement tools. In addition, we analyze potential noninvasive biomarkers for tracking disease processes and monitoring treatment effects, and explore effective algorithms consisting of imaging and nonimaging biomarkers for diagnosing advanced fibrosis and reducing unnecessary biopsies in clinical practice.