Assessing significant fibrosis using imaging-based elastography in chronic hepatitis B patients: Pilot study

BACKGROUND Accurate detection of significant fibrosis(fibrosis stage 2 or higher on the METAVIR scale)is important especially for chronic hepatitis B(CHB)patients with high viral loads but with normal or mildly elevated alanine aminotransferase(ALT)levels because the presence of significant fibrosis is accepted as the indication for antiviral treatment.Liver biopsy is the reference standard for diagnosing significant fibrosis,but it is an invasive procedure.Consequently,noninvasive imaging-based measurements,such as magnetic resonance elastography(MRE)or two-dimensional shear-wave elastography(2DSWE),have been proposed for the quantitative assessment of liver fibrosis.AIM To explore MRE and 2D-SWE to identify fibrosis stage,and to compare their performance with that of serum-based indices.METHODS The study enrolled 63 treatment-na?ve CHB patients with high viral loads but with normal or mildly elevated ALT levels who underwent liver biopsy before a decision was made to initiate antiviral therapy.MRE and 2D-SWE were performed,and serum-based indices,such as FIB-4 and aspartate transaminase to platelet ratio index(APRI),were calculated.The diagnostic performances of MRE,2D-SWE,FIB-4,and APRI for assessing significant fibrosis(≥F2)and cirrhosis(F4)were evaluated with liver histology as the reference standard,using receiver operating characteristic analyses.RESULTS The liver fibrosis stage was F0/F1 in 19,F2 in 14,F3 in 14,and F4 in 16 patients,respectively.MRE significantly discriminated F2 from F0/1(P=0.022),whereas 2D-SWE showed a broad overlap in distinguishing those stages.MRE showed a higher correlation coefficient value with fibrosis stage than 2D-SWE with fibrosis stage(0.869 vs 0.649,Spearman test;P<0.001).Multivariate linear regression analyses showed that fibrosis stage was the only factor affecting the values of MRE(P<0.001),whereas body mass index(P=0.042)and fibrosis stage(P<0.001)were independent factors affecting 2D-SWE values.MRE performance for diagnosing significant fibrosis was better[area under the curve(AUC)=0.906,positive predictive value(PPV)97.3%,negative predictive value(NPV)69.2%]than that of FIB-4(AUC=0.697,P=0.002)and APRI(AUC=0.717,P=0.010),whereas the performance of 2D-SWE(AUC=0.843,PPV 86%,NPV 65%)was not significantly different from that of FIB-4 or APRI.CONCLUSION Compared to SWE,MRE might be more precise non-invasive assessment for depicting significant fibrosis and for making-decision to initiate antiviral-therapy in treatment-na?ve CHB patients with normal or mildly-elevated ALT levels.

Benign gallbladder diseases:Imaging techniques and tips for differentiating with malignant gallbladder diseases

Benign gallbladder diseases usually present with intraluminal lesions and localized or diffuse wall thickening.Intraluminal lesions of the gallbladder include gallstones,cholesterol polyps,adenomas,or sludge and polypoid type of gallbladder cancer must subsequently be excluded.Polyp size,stalk width,and enhancement intensity on contrast-enhanced ultrasound and degree of diffusion restriction may help differentiate cholesterol polyps and adenomas from gallbladder cancer.Localized gallbladder wall thickening is largely due to segmental or focal gallbladder adenomyomatosis,although infiltrative cancer may present similarly.Identification of Rokitansky-Aschoff sinuses is pivotal in diagnosing adenomyomatosis.The layered pattern,degree of enhancement,and integrity of the wall are imaging clues that help discriminate innocuous thickening from gallbladder cancer.High-resolution ultrasound is especially useful for analyzing the layering of gallbladder wall.A diffusely thickened wall is frequently seen in inflammatory processes of the gallbladder.Nevertheless,it is important to check for coexistent cancer in instances of acute cholecystitis.Ultrasound used alone is limited in evaluating complicated cholecystitis and often requires complementary computed tomography.In chronic cholecystitis,preservation of a two-layered wall and weak wall enhancement are diagnostic clues for excluding malignancy.Magnetic resonance imaging in conjunction with diffusion-weighted imaging helps to differentiate xathogranulomatous cholecystitis from gallbladder cancer by identifying the presence of fat and degree of diffusion restriction.Such distinctions require a familiarity with typical imaging features of various gallbladder diseases and an understanding of the roles that assorted imaging modalities play in gallbladder evaluations.

Three-Tesla magnetic resonance elastography for hepatic fibrosis:Comparison with diffusion-weighted imaging and gadoxetic acid-enhanced magnetic resonance imaging

AIM:To evaluate the feasibility of 3-Tesla magnetic resonance elastography(MRE)for hepatic fibrosis and to compare that with diffusion-weighted imaging(DWI)and gadoxetic acid-enhanced magnetic resonance(MR)imaging.METHODS:Forty-two patients were included in the study.On MRE,mean stiffness values were measured on the elastograms in kilopascals.The apparent diffusion coefficient(ADC)of the liver was measured using DWI.On gadoxetic acid enhanced MR,the contrast enhancement index(CEI)was calculated as signal intensity(SI)post/SIpre,where SIpost is liver-to-muscle SI ratio on hepatobiliary phase images and SIpre is that on nonenhanced images.Correlation between aspartate aminotransferase to the platelet ratio index(APRI)and three MR parameters was assessed.Each MR parameter was compared between a hepatic fibrosis(HF)group and non-hepatic fibrosis(n HF)group.RESULTS:Liver stiffness showed strong positive correlation with APRI[Spearman correlation coeffiecient(r)=0.773,P<0.0001],while ADC and CEI showed weak or prominent negative correlation(r=-0.28 and-0.321,respectively).In the HF group,only liver stiffness showed strong correlation with APRI(r=0.731,P<0.0001).Liver stiffness,ADC,and APRI were significantly different between the HF group and n HF group.CONCLUSION:MRE at 3-Tesla could be a feasible method for the assessment of hepatic fibrosis.