Ultrasound elastography: liver

Abstract

Ultrasound elastography, also termed sonoelastography, is being used increasingly in clinical practice to aid the diagnosis and management of diffuse liver disease. Elastography has been shown to be capable of differentiating advanced and early-stage liver fibrosis, and consequently a major application in clinical liver care includes progression to cirrhosis risk stratification through (1) assessment of liver fibrosis stage in HCV and HBV patients, (2) distinguishing non-alcoholic steatohepatitis from simple steatosis in non-alcoholic fatty liver disease patients, and (3) prognostic evaluation of liver disease is autoimmune liver disease. In addition, elastographic characterization of focal liver lesions and evaluation of clinically significant portal hypertension have the potential to be clinically useful and are areas of active clinical research.

Fig. 1.

Strain elastography in a healthy liver (A) and in a liver with moderate fibrosis (B). *Images courtesy of Hitachi Aloka Medical.

Fig. 2.

Pathophysiology of liver fibrosis, if left untreated it progresses to cirrhosis irrespective of the etiology of chronic liver disease. Reprinted from [6].

Fig. 3.

Panel A: A SWE elastogram of a 65-year-old male with chronic hepatitis C with Stage F0 fibrosis on pathological examination shows an estimated liver Young’s modulus of 5.9 kPa. Panel B: A SWE elastogram in a 60-year-old male with chronic hepatitis C with stage F3 fibrosis on pathological examination shows an estimated liver Young’s modulus of 13.4 kPa. The B-mode images are indistinguishable.

Fig. 4.

Box and whisker plot showing liver stiffness values for different liver fibrosis stages as seen on liver biopsy. The study included 911 patients in a large multi-center trial using ARFI shear wave elastography. Reprinted from [49].

Fig. 5.

Panel A: A SWE elastogram of a 35-year-old male patient with Grade 4 steatosis but no inflammation or fibrosis shows an estimated Young’s modulus of 5.5 kPa, below the cut-off for the diagnosis of stage F1 fibrosis. Panel B: A SWE elastogram depicts a SWE Young’s modulus estimate of 8.5 kPa in a patient that has the same stage of fibrosis (Stage F0), lesser steatosis (grade 3) but more inflammation as characterized by a total activity score of 1/3 on METAVIR grading after liver biopsy. The B-mode images are indistinguishable.