Onishi, Hiroshi

AbstractBackgroundThe damping ratio (DR) and the loss modulus (G″) obtained by 3D MR elastography complex modulus analysis has been reported recently to reflect early intrahepatic inflammation, and is expected to be a noninvasive biomarker of inflammation in nonalcoholic fatty liver disease (NAFLD). However, the role of the DR and the G″ in Japanese NAFLD patients remains unclear.MethodsWe enrolled 39 Japanese patients with NAFLD who underwent liver biopsy and 3D MR elastography within 1 month and analyzed the association between DR, G″, and histological activity.ResultsRegarding DR, no evident correlation was observed between the DR and histological activity (p = 0.14) when patients with all fibrosis stages were included. However, when patients were restricted up to stage F2 fibrosis, the association of the DR and inflammation became significant, the DR increasing with the degree of activity (p = 0.02). Among the constituents of fibrosis activity, ballooning correlated with the DR (p < 0.01) while lobular inflammation did not. Regarding G″, it was correlated with histological activity (p < 0.01), ballooning (p < 0.01), and lobular inflammation (p < 0.01) in patients with all fibrosis stages and in patients up to F2 fibrosis (p = 0.03 for activity and p = 0.04 for ballooning). The best cutoff value of DR for hepatitis activity in patients within the F2 stage was 0.094 (area under the receiver operating characteristic curve 0.775, 95% CI: 0.529–1.000) and G″ was 0.402 (area under the receiver operating characteristic curve 0.825, 95% CI: 0.628–1.000).ConclusionsThe DR and G″ reflected the histological activity in Japanese patients with NAFLD during the early stage, indicating these values for noninvasive diagnosis of inflammation in Japanese patients with NAFLD.

BackgroundAn understanding of potential age‐related changes in brain stiffness and its regional variation is important for further clinical application of MR elastography.PurposeTo investigate the effect of age on global and regional brain stiffness in young and middle‐aged adults.Study TypeProspective.SubjectsFifty subjects with normal brains and aged in their 20s, 30s, 40s, 50s, or 60s (five men, five women per decade).Field Strength/Sequence3.0T MRI and elastography with a vibration frequency of 60 Hz.AssessmentStiffness was measured in nine brain regions (cerebrum, temporal lobes, sensorimotor areas, frontotemporal composite region, deep gray matter and white matter (deep GM/WM), parietal lobes, occipital lobes, frontal lobes, and cerebellum) using an atlas‐based region‐of‐interest approach. The influence of age on regional brain stiffness was evaluated.Statistical TestsMultiple linear regression analysis, followed by Dunnett's multiple comparisons test, using subjects in their 20s as controls.ResultsFollowing adjustment for sex, multiple linear regression revealed a significant negative correlation between age and stiffness of the cerebrum (P < 0.0001), temporal lobes (P < 0.0001), sensorimotor areas (P < 0.0001), frontotemporal composite region (P < 0.0001), deep GM/WM (P = 0.0028), parietal lobes (P < 0.0001), occipital lobes (P = 0.0055), and frontal lobes (P < 0.0001). Dunnett's multiple comparison test showed that the stiffness of the sensorimotor areas, frontotemporal composite region, and frontal lobes was significantly decreased in subjects in their 40s (P < 0.0367), 50s (P < 0.0001), and 60s (P < 0.0001), while that of the cerebrum, temporal lobes, and parietal lobes was significantly decreased only in subjects in their 50s (P < 0.0012) and 60s (P < 0.0031) when compared with the controls.Data ConclusionThere is an age‐related decrease in brain stiffness that varies across the different regions.Level of Evidence: 1Technical Efficacy Stage: 2J. Magn. Reson. Imaging 2020;51:727–733.

PurposeTo evaluate the effect of imaging sequence (spin‐echo echo‐planar imaging [EPI] and gradient‐echo [GRE]) and postprocessing method (two‐dimensional [2D] and 3D inversion algorithms) on liver MR elastography (MRE) and to validate the diagnostic performance of EPI‐MRE3D versus conventional GRE‐MRE2D for liver fibrosis staging.Materials and MethodsThree MRE methods (EPI‐MRE3D, EPI‐MRE2D, and GRE‐MRE2D) were performed on soft and mildly stiff phantoms and 58 patients with chronic liver disease using a 3 Tesla clinical MRI scanner, and stiffness values were compared among the three methods. A validation study comprised 73 patients with histological liver fibrosis (F0–4, METAVIR system). Areas under the receiver operating characteristic curves (AUCs) and accuracies for diagnosing significant fibrosis (F3–4) and cirrhosis (F4) were compared between EPI‐MRE3D and GRE‐MRE2D.ResultsStiffness values of the soft and mildly stiff phantoms were 2.4 kPa and 4.0 kPa by EPI‐MRE3D; 2.6 kPa and 4.2 kPa by EPI‐MRE2D; and 2.7 kPa and 4.2 kPa by GRE‐MRE2D. In patients, EPI‐MRE3D provided significantly lower stiffness values than other methods (P < 0.001). However, there was no significant difference between GRE‐MRE2D and EPI‐MRE2D (P = 0.12). The AUCs and accuracies of EPI‐MRE3D and GRE‐MRE2D were statistically equivalent in the diagnoses of significant fibrosis (F3–4) and cirrhosis (F4) (all P < 0.005).ConclusionEPI‐MRE3D showed modestly lower liver stiffness values than conventional GRE‐MRE2D. The diagnostic performances of EPI‐MRE3D and GRE‐MRE2D were equivalent for liver fibrosis staging.Level of Evidence: 3J. Magn. Reson. Imaging 2017;45:1163–1170