Shear wave velocity is a useful marker for managing nonalcoholic steatohepatitis

Abstract

Aim: To investigate whether a noninvasive measurement of tissue strain has a potential usefulness for management of nonalcoholic steatohepatitis (NASH).

Methods: In total 26 patients, 23 NASHs and 3 normal controls were enrolled in this study. NASH was staged based on Brunt criterion. At a region of interest (ROI), a shear wave was evoked by implementing an acoustic radiation force impulse (ARFI), and the propagation velocity was quantified.

Results: Shear wave velocity (SWV) could be reproducibly quantified at all ROIs in all subjects except for 4 NASH cases, in which a reliable SWV value was not calculated at several ROIs. An average SWV of 1.34 +/- 0.26 m/s in fibrous stage 0-1 was significantly slower than 2.20 +/- 0.74 m/s and 2.90 +/- 1.01 m/s in stages 3 and 4, respectively, but was not significantly different from 1.79 +/- 0.78 m/s in stage 2. When a cutoff value was set at 1.47 m/s, receiver operating characteristic analysis showed significance to dissociate stages 3 and 4 from stage 0-1 (P = 0.0092) with sensitivity, specificity and area under curve of 100%, 75% and 94.2%, respectively. In addition, the correlation between SWV and hyaluronic acid was significant (P < 0.0001), while a tendency toward negative correlation was observed with serum albumin (P = 0.053).

Conclusion: The clinical implementation of ARFI provides noninvasive repeated evaluations of liver stiffness at an arbitrary position, which has the potential to shed new light on NASH management.

Figure 1

Reliability and variation of shear wave velocity (SWV) throughout the liver. SWV was measured independently three times at each of the right (Rt) or left (Lt) lobes in four patients with fibrosis stage 3, labeled cases 10 to 13. Each horizontal bar indicates an average SWV.

Figure 2

Average shear wave velocity (SWV) and representative photomicrographs in each fibrosis stage. SWV was measured in four segments; right anterior, right posterior, left medial and left lateral segments, and the average was calculated based on data from four segments (A) or from either one of right [Rt, (C)] or left [Lt, (D)] lobes. Histological fibrosis stages were judged along with Brunt criterion. Each horizontal bar indicates an average SWV. ^aP < 0.05. The photomicrographs (B) are representative Masson’s trichrome stains for fibrosis stages 1, 2, 3 and 4 from upper left, lower left, and upper right to lower right panels, respectively. Original magnification is × 100.

Figure 3

Receiver-operator characteristic curve (ROC) of SWV or platelet count to distinguish fibrosis stages 3 and 4 from stage 0-1. ROC to discriminate fibrosis stages 3 and 4 from stage 0-1 by SWV (A) or platelet count (B) revealed sensitivity, specificity and area under ROC of 100%, 75% and 94.2%, or 100%, 57.1% and 61%, respectively, when 1.47 m/s or 17.8 × 10 000/mm³ was selected as a cutoff value. A small graph incorporated in each ROC graph shows the distribution of SWV or platelet count in fibrosis stages 0-1 and 3-4. The dotted line indicates the cut-off value selected.

Figure 4

Correlation between SWV and serum biochemical parameters. SWV was plotted against hyaluronic acid (A) and serum concentration of albumin (B). A gray scale indicates the fibrosis stages, with white representing 0-1 through to dark gray for stage 4.