Noninvasive evaluation of hepatic fibrosis using acoustic radiation force-based shear stiffness in patients with nonalcoholic fatty liver disease

Abstract

Background & Aims Nonalcoholic fatty liver disease (NAFLD), the most common form of chronic liver disease in developed countries, may progress to nonalcoholic steatohepatitis (NASH) in a minority of people. Those with NASH are at increased risk for cirrhosis and hepatocellular carcinoma. The potential risk and economic burden of utilizing liver biopsy to stage NAFLD in an overwhelmingly large at-risk population are enormous; thus, the discovery of sensitive, inexpensive, and reliable noninvasive diagnostic modalities is essential for population-based screening. Methods Acoustic Radiation Force Impulse (ARFI) shear wave imaging, a noninvasive method of assessing tissue stiffness, was used to evaluate liver fibrosis in 172 patients diagnosed with NAFLD. Liver shear stiffness measures in 3 different imaging locations were reconstructed and compared to the histologic features of NAFLD and AST-to-platelet ratio indices (APRI). Results Reconstructed shear stiffnesses were not associated with ballooned hepatocytes (p = 0.11), inflammation (p = 0.69), nor imaging location (p = 0.11). Using a predictive shear stiffness threshold of 4.24 kPa, shear stiffness distinguished low (fibrosis stage 0–2) from high (fibrosis stage 3–4) fibrosis stages with a sensitivity of 90% and a specificity of 90% (AUC of 0.90). Shear stiffness had a mild correlation with APRI (R2 = 0.22). BMI > 40 kg/m2 was not a limiting factor for ARFI imaging, and no correlation was noted between BMI and shear stiffness (R2 = 0.05). Conclusions ARFI imaging is a promising imaging modality for assessing the presence or absence of advanced fibrosis in patients with obesity-related liver disease.

Acoustic radiation force-based elasticity imaging methods

“…An example of the relationship between radiation force-derived shear modulus estimates and biopsy proven hepatic fibrosis stage is shown in figure 4 [57].…”

Noninvasive imaging assessment of non-alcoholic fatty liver disease: Focus on liver scintigraphy

“…In that study, BMI > 40 kg/m 2 was not a limiting factor for ARFI imaging, and no correlation was noted between BMI and shear stiffness. As a result, the authors concluded that ARFI is a promising imaging modality for detecting advanced fibrosis in patients with obesity-related liver disease [50] . TE and ARFI using the standard or the XL probes were also compared for the diagnosis of liver fibrosis in 61 patients with NAFLD/NASH [53] .…”

“…With this method, the elasticity of the liver is calculated from short-duration acoustic pulses of a fixed frequency targeted to one region. As with TE, the result is expressed in kPa [35,50] . ARFI has been suggested for patients with a high BMI [51] , which can affect the accuracy of liver stiffness measurements.…”

“…ARFI has been suggested for patients with a high BMI [51] , which can affect the accuracy of liver stiffness measurements. AUROCs reported with ARFI for the diagnosis of F3-F4 in NAFLD ranged from 0.74 to 0.97 [43,50,52,53] . One study evaluating liver stiffness in 54 patients with biopsy-confirmed NAFLD and 10 healthy volunteers found a significant correlation between ARFI and TE [43] .…”

“…Furthermore, there was a significant positive correlation between ARFI and severity of liver fibrosis in patients with NAFLD, and the results were similar to those of TE [43] . Another study evaluating 172 NAFLD patients used a predictive shear stiffness threshold of 4.24 kPa and found that shear stiffness distinguished low (0-2) from high (3-4) fibrosis stages with a sensitivity and specificity of 90% (AUROC of 0.90) [50] . In that study, BMI > 40 kg/m 2 was not a limiting factor for ARFI imaging, and no correlation was noted between BMI and shear stiffness.…”