Diagnosis of fatty liver with MR imaging

Abstract

The diagnosis of fatty liver with magnetic resonance (MR) imaging was evaluated in experimental rat models of simple fatty infiltration and fatty liver with hepatocellular injury. T1 and T2 were measured ex vivo and correlated with the histologic degree of fatty infiltration. Enhancement of fatty liver with four different cells-specific contrast agents was studied with ex vivo relaxometry and in vivo MR imaging. Quantitative analysis of conventional and chemical shift MR images was correlated with biochemically determined fat content of the liver. Diet-induced simple fatty infiltration of the liver caused a decrease in T1 of 15%, whereas the T1 of L-ethionine-induced fatty liver with hepatocellular injury increased by 12%. T2 showed a positive correlation with the degree of fatty infiltration in both models. Cell-specific hepatobiliary contrast agents showed the same liver uptake and relaxation enhancement in fatty livers as in normal livers. Conventional T1-weighted images and chemical shift images showed good correlation (r = .83 and .80, respectively) between signal intensity and the degree of fatty infiltration. However, only chemical shift imaging was reliable in the diagnosis of fatty liver.

In vivo magnetic resonance (MR) study of fatty liver: Importance of intracellular ultrastructural alteration for MR tissue parameters change

“…Prolonged T 1water was reported by Hazle et al (8) and Ling and Brauer (30). However, in protein-depleted fatty liver (8) and sucrose/orotic acid-induced fatty liver (19), the T1 value was shortened.…”

“…In the past decades, however, many studies have reported the various changes of relaxation times in fatty liver induced by different experimental models (15)(16)(17)(18)(19). By single exponential hypothesis, the statistically significantly shorter T1 relaxation time and longer T2 relaxation time for fat than for water would suggest that the global T1 and T2 found in liver with fatty infiltration would be decreased and increased.…”

Liver Steatosis: Investigation of Opposed-Phase T1-weighted Liver MR Signal Intensity Loss and Visceral Fat Measurement as Biomarkers

“…A small number of additional studies (8)(9)(10) have also shown the ability to measure liver fat with T1-weighted MR imaging. By using …”

“…Bahl et al rat models of simple fatty infiltration and fatty liver with hepatocellular injury, Kreft et al (8) found that conventional T1-weighted images and chemical shift images showed good correlation (r ϭ 0.83 and 0.80, respectively) between SI and the degree of steatosis, although only chemical shift imaging was reportedly reliable. Qayyum et al (10) demonstrated that liver fat may be quantified with both opposed-phase gradient-echo and fat-suppressed fast spinecho MR imaging (r ϭ 0.69 and 0.92, respectively; P Ͻ .01) in patients without cirrhosis (n ϭ 11).…”

“…Liver steatosis is linked to obesity because, in obese subjects, visceral fat functions as an endocrine organ by producing inflammatory mediators that interfere with hepatic glucose metabolism and cause insulin resistance and liver steatosis (1,5,6). Some studies (7)(8)(9)(10) have investigated the ability of magnetic resonance (MR) imaging to help detect liver steatosis in patients with diffuse liver disease. Clinically calculated body mass index (BMI) (patient's body weight divided by the square of his or her height) has often been used as a surrogate anthropometric marker of obesity-related morbidity, even though this measurement does not account for body tissue composition or distribution of body fat.…”