Acoustic radiation force impulse elastography in differentiating renal solid masses: a preliminary experience.

New diagnostic methods are required to diagnose renal mass. Thus, we assessed virtual tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) elastography in differentiation of renal solid masses. Forty-two patients with renal masses were assessed by VTQ in terms of measurement of the shear wave velocity (SWV). The masses were divided into three groups. They were clear cell carcinoma (CCC) angiomyolipoma (AML), and pseudotumor. The differences among the three groups in SWV, as well as between masses and its surrounding parenchyma, were investigated. Receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic performance. We found that the SWV among the three groups were significant different (F = 6.976, P = 0.003) and the SWV of pseudotumor (3.14 ± 0.75 m/s) was significantly higher than CCC (2.46 ± 0.45 m/s) and AML (2.49 ± 0.63 m/s) (P = 0.007 and 0.001 respectively). There were no significant difference between CCC and AML in SWV (P = 0.719). For each group, there was no significant difference between the mass and its surrounding parenchyma (P = 0.693, 0.892, and 0.714, respectively). Between pseudotumor and CCC, the optimal cut-off value of SWV for differential diagnoses was 3.07 m/s; and the area under the ROC curve (AUC) was 0.78 (95% CI: 0.560 to 0.924) (P = 0.004), the sensitivity and specificity were 100% and 58.3%, respectively. Between pseudotumor and AML, the optimal cut-off value of SWV for differential diagnoses was 3.03 m/s, thus AUC curve was 0.786 (95% CI: 0.591 to 0.918) (P = 0.002), the sensitivity and specificity were 100% and 58.3%, respectively. No significant difference was found between AML and CCC (P = 0.587) and the AUC was 0.562. To conclude, our results support that ARFI has potential value in differentiation between CCC and pseudotumor, or between AML and pseudotumor, however, it fails to make a distinction between CCC and AML.