Longitudinal fat fraction, liver stiffness may signal rapid progression in NAFLD
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The temporal change rate of proton density fat fraction and liver stiffness measurement are promising predictors for those at high risk for rapid clinical progression and may improve patient management in those with nonalcoholic fatty liver disease.
“From our observation, at the early fibrosis stages, the rate of change of liver stiffness measurement (LSM) is slow and positively correlated with the rate of change in proton-density fat fraction (delta PDFF),” Meng Yin, MD, from Mayo Clinic, told Healio Gastroenterology. “At later fibrosis stages, the rate of change in LSM is higher and is negatively correlated with delta PDFF. Compared with other risk factors, the baseline value of LSM and the rate of change in PDFF were most strongly associated with subsequent change in LSM.”
Imaging examination
Zheng Zhu, MD, from the Mayo Clinic, who presented the results at Digital NAFLD Summit 2021, Yin, and colleagues retrospectively identified 384 patients with NAFLD with at least one multiparametric MRI/MR elastography exam. After adjusting for identified influencing factors, investigators used linear regression to evaluate the impact of proton density fat fraction on liver stiffness measurement. Within 1 year, 256 patients had liver biopsy; 128 patients had serial MRI/MRE exams. Median follow-up was 4 years.
Researchers defined significant LSM change by a z score of 1.98 or greater with a sigma level of 0.1. They assessed LSM and PDFF change per year using Spearman’s correlation among groups regarding dichotomous classifications based on the presence of cirrhosis, type 2 diabetes, obesity, hyperlipidemia, hypertension and obstructive sleep apnea. Investigators predicted delta LSM with delta PDFF and baseline LSM with a generalized linear model.
Change in liver stiffness, PDFF
Results showed no correlation between LSM and PDFF (P = .069) after researchers adjusted for fibrosis stages and age in patients with the presence of steatosis (ie, PDFF > 5%). Thirty-six patients had significant liver stiffness changes (56% women; mean age, 59 years; BMI = 33.5 kg/m2; 50% with > 2 MRE).
Yin said liver stiffness measured with MRE was not affected by the presence of liver fat.
“Specifically, elevated liver fat, which is a hallmark of fatty liver disease, does not bias MRE-based liver stiffness measurements, and therefore does not affect the accuracy of measurement of liver fibrosis,” Yin said.
According to Zhu, change rates among non-cirrhotic livers was low. In addition, there was a positive association between the delta LSM and delta PDFF (delta LSM = –0.19+0.071 x delta PDFF; r = 0.4). Investigators also observed high change rates in cirrhotic livers and a negative association (delta LSM = 0.51-0.1 x delta PDFF; r = 0.58). Significant factors that could determine delta LSM were baseline LSM (P = .0001) and delta PDFF (P = .0043).
“In the clinical management of nonalcoholic fatty liver disease, a combination of baseline liver stiffness measurements and temporal change (as well as the direction of change) in fat fraction has the potential to predict fibrosis progression rate, thus identifying individuals at high risk of rapid progression,” Yin said.
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Zhu Z, et al. Abstract: OS-133. Presented at: Digital NAFLD Summit 2021; Sept. 16-17, 2021 (virtual meeting).
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