Noninvasive Diagnosis of Nonalcoholic Fatty Liver Disease and Quantification of Liver Fat Using a New Quantitative Ultrasound Technique

Abstract

Background & Aims Liver biopsy analysis is the standard method used to diagnose nonalcoholic fatty liver disease (NAFLD). Advanced magnetic resonance imaging is a noninvasive procedure that can accurately diagnose and quantify steatosis, but is expensive. Conventional ultrasound is more accessible but identifies steatosis with low levels of sensitivity, specificity, and quantitative accuracy, and results vary among operators. A new quantitative ultrasound (QUS) technique can identify steatosis in animal models. We assessed the accuracy of QUS in the diagnosis and quantification hepatic steatosis, comparing findings with those from MRI proton density fat fraction (MRI-PDFF) analysis as a reference. Methods We performed a prospective, cross-sectional analysis of a cohort of adults (n=204) with NAFLD (MRI-PDFF≥5%) and without NAFLD (controls). Subjects underwent MRI-PDFF and QUS analyses of the liver on the same day at the University of California, San Diego, from February 2012 through March 2014. QUS parameters and backscatter coefficient (BSC) values were calculated. Patients were randomly assigned to training (n=102; mean age, 51±17 years; mean body mass index, 31±7 kg/m2) and validation (n=102; mean age, 49±17 years; body mass index, 30±6 kg/m2) groups; 69% of patients in each group had NAFLD. Results BSC (range 0.00005–0.25 1/cm-sr) correlated with MRI-PDFF (Spearman’s ρ=0.80; P<.0001). In the training group, the BSC analysis identified patients with NAFLD with an area under the curve value of 0.98 (95% confidence interval, 0.95–1.00; P<.0001). The optimal BSC cutoff value identified patients with NAFLD in the training and validation groups with 93% and 87% sensitivity, 97% and 91% specificity, 86% and 76% negative predictive values, and 99% and 95% positive predictive values, respectively. Conclusions QUS measurements of BSC can accurately diagnose and quantify hepatic steatosis, based on a cross-sectional analysis that used MRI-PDFF as the reference. With further validation, QUS could be an inexpensive, widely available method to screen the general or at-risk population for NAFLD.

Robust sound speed estimation for ultrasound-based hepatic steatosis assessment

“…This CAP technique is performed in conjunction with liver fibrosis assessment based on 1D Transient Elastography (Foucher et al 2006b, Sandrin et al 2002. Other recent studies have used ultrasound to detect steatosis (Lin et al 2015, Son et al 2015 but they are based on a single cutoff value. Beyond such binary below/above diagnosis, there is a real clinical unmet need for a non-expensive, widely available, and highly reliable technique to precisely grade hepatic steatosis as MRI does.…”

Deletion of the K1L Gene Results in a Vaccinia Virus That Is Less Pathogenic Due to Muted Innate Immune Responses, yet Still Elicits Protective Immunity

“…To generate the BSC image, the FOI was divided into 75%-overlapped sub-regions of interest (sub-ROIs) with dimensions of 193 m by193 m (equivalent to 4 by 4 wavelengths at 32 MHz). For each sub-ROI, a BSC value was estimated using the reference phantom technique (77,78), yielding a BSC versus ultrasonic frequency curve. Each sub-ROI's BSC value was generated by averaging the BSC over the frequency range from 25 to 43 MHz, denoted BSC (25 to 43 MHz), with a color then assigned to each BSC (25 to 43 MHz) value.…”

Cardiovascular risk assessment in the treatment of nonalcoholic steatohepatitis: a secondary analysis of the MOZART trial

“…Furthermore, there may be a role for CAC scores in assessing long-term, longitudinal cardiovascular risk among patients with NASH [Kim et al 2012;Budoff et al 2013]. Other imaging modalities to assess cardiovascular risk, such as cardiac MRI or quantitative ultrasound [Lin et al 2014] to quantify hepatic steatosis, which has been associated with cardiovascular disease [Arulanandan et al 2015], may be utilized in future trials. Measures of vascular and endothelial dysfunction, such as the ankle-brachial index, measures of flow-mediated dilation and carotid intima-media thickness [Sookoian and Pirola, 2008;Kozakova et al 2012], may be potential cardiovascular endpoints in future NASH trials.…”