Purpose
To reveal the ability of S-Map strain elastography to diagnose fibrosis in nonalcoholic fatty liver disease (NAFLD) and to compare its diagnostic ability with that of shear wave elastography (SWE).
Methods
Participants were patients with NAFLD who were scheduled to undergo liver biopsy at our institution between 2015 and 2019. A GE Healthcare LOGIQ E9 ultrasound system was used. For S-Map, the right lobe of the liver was visualized in the section where the heartbeat was detected by right intercostal scanning, a 4 × 2-cm region of interest (ROI) was defined at 5 cm from the liver surface, and ROI strain images were acquired. Measurements were repeated six times, with the average taken as the S-Map value. Correlations of S-Map and SWE values with fibrosis stage determined by liver biopsy were analyzed using multiple comparisons. The diagnostic performance of S-Map for fibrosis staging was assessed using receiver operating characteristic curves.
Results
In total, 107 patients (65 men, 42 women; mean age 51 ± 14 years) were analyzed. The S-Map value by fibrosis stage was 34.4 ± 10.9 for F0, 32.9 ± 9.1 for F1, 29.5 ± 5.6 for F2, 26.7 ± 6.0 for F3, and 22.8 ± 4.19 for F4. By fibrosis stage, the SWE value was 1.27 ± 0.25 for F0, 1.39 ± 0.20 for F1, 1.59 ± 0.20 for F2, 1.64 ± 0.17 for F3, and 1.88 ± 0.19 for F4. The diagnostic performance of S-Map (measured by area under the curve) was 0.75 for F2, 0.80 for F3, and 0.85 for F4. The diagnostic performance of SWE (measured by area under the curve) was 0.88 for F2, 0.87 for F3, and 0.92 for F4.
Conclusion
S-Map strain elastography was inferior to SWE in terms of ability to diagnose fibrosis in NAFLD.
