Liver fat imaging—a clinical overview of ultrasound, CT, and MR imaging

Abstract

Hepatic steatosis is a frequently encountered imaging finding that may indicate chronic liver disease, the most common of which is non-alcoholic fatty liver disease. Non-alcoholic fatty liver disease is implicated in the development of systemic diseases and its progressive phenotype, non-alcoholic steatohepatitis, leads to increased liver-specific morbidity and mortality. With the rising obesity epidemic and advent of novel therapeutics aimed at altering metabolism, there is a growing need to quantify and monitor liver steatosis. Imaging methods for assessing steatosis range from simple and qualitative to complex and highly accurate metrics. Ultrasound may be appropriate in some clinical instances as a screening modality to identify the presence of abnormal liver morphology. However, it lacks sufficient specificity and sensitivity to constitute a diagnostic modality for instigating and monitoring therapy. Newer ultrasound techniques such as quantitative ultrasound show promise in turning qualitative assessment of steatosis on conventional ultrasound into quantitative measurements. Conventional unenhanced CT is capable of detecting and quantifying moderate to severe steatosis but is inaccurate at diagnosing mild steatosis and involves the use of radiation. Newer CT techniques, like dual energy CT, show potential in expanding the role of CT in quantifying steatosis. MRI proton-density fat fraction is currently the most accurate and precise imaging biomarker to quantify liver steatosis. As such, proton-density fat fraction is the most appropriate noninvasive end point for steatosis reduction in clinical trials and therapy response assessment.

Non‐alcoholic fatty liver disease in pediatric type 2 diabetes: Metabolic and histologic characteristics in 38 subjects

“…The degree of steatosis in our study cohort was significantly correlated with the presence of NASH. This may be clinically significant, as steatosis can be evaluated using magnetic resonance imaging–estimated proton density fat fraction (PDFF) . A recent study in adults with NASH found that PDFF correlates well with histologic hepatic steatosis grade .…”

“…This may be clinically significant, as steatosis can be evaluated using magnetic resonance imaging-estimated proton density fat fraction (PDFF). 16 A recent study in adults with NASH found that PDFF correlates well with histologic hepatic steatosis grade. 17 If steatosis degree in children is indeed correlated with the presence of NASH, and if steatosis can be estimated using non-invasive PDFF, this may eventually negate the need for invasive liver biopsies in some patients.…”

Lipid accumulation product independently correlate with hepatic steatosis quantified by controlled attenuation parameter in women with polycystic ovary syndrome

“…However, liver biopsy cannot be performed in all patients, as it is an expensive and invasive procedure which limits its use for the screening of population (6). Thus, several studies developed noninvasive imaging techniques such as ultrasonography, computerized tomography (CT) and MRI to clinically assess HS in NAFLD (7,8). However, ultrasonography is observer dependent, CT induces radiation exposure, and MRI is not routinely accessible.…”

Impact of Androgen Deprivation Therapy on Non-Alcoholic Fatty Liver Disease in Patients with Prostate Cancer: A CT Evaluation

“…However, liver biopsy is an invasive procedure with a non-negligible risk of significant morbidity and mortality. MRI is the most sensitive and specific noninvasive technique for assessing hepatic steatosis [18] and may be better for detecting the development or progression of NAFLD after ADT. Progression of NAFLD was identified after 6 months of ADT in patients with PCa and was strongly correlated with changes in HbA 1c , abdominal circumference, and BMI.…”