How liver pathologies contribute to T1rho contrast require more careful studies

Liver T1rho has been proposed as an imaging biomarker for liver fibrosis (1-5). In the recent study of Xie et al. (6,7), 18 healthy subjects, 18 patients with fatty liver, and 18 patients with liver fibrosis had T1rho MR imaging performed. The diagnosis of liver fibrosis was based on serologic evidence of hepatitis B or C virus infection and liver stiffness criteria by ultrasonic elastography. Mean liver T1rho values in fibrotic group (52.6±6.8 ms) were significantly higher than those of healthy subjects (44.9±2.8 ms, P<0.001) and fatty liver group (45.0±3.5 ms, P<0.001), while mean liver T1rho values were similar between healthy subjects and fatty liver group (P=0.999). However, four liver fibrosis cases (4/18, 22.2%) had liver T1rho overlapped with those of control subjects (the first figure of Xie et al.’s paper) (7). Since there was no histologic diagnosis of liver fibrosis for the patients, it is possible that these four cases actually did not have fibrosis; however, it is more likely that these patients did have liver fibrosis, but their liver T1rho was not measured higher than healthy subjects’ liver.