Virtual Touch quantification using acoustic radiation force impulse (ARFI) technology for the evaluation of focal...

To evaluate potential value of Virtual Touch quantification (VTQ) of acoustic radiation force impulse (ARFI) imaging for characterising focal solid renal lesions.

Two independent operators performed 10 and five measurements of each lesion and adjacent renal cortex, respectively. Mean shear wave velocity (SWV) and shear wave velocity ratio (SWR) of histotypes were compared.

One hundred and ninety-seven renal lesions were evaluated, including 155 renal cell carcinomas (RCCs; 129 clear-cell RCCs [ccRCCs], 14 papillary RCCs [pRCCs], and 12 chromophobe RCCs [cRCCs]) and 42 angiomyolipomas (AMLs). The interoperator reproducibility of SWV of renal tumours and renal cortex were good (ICC=0.852, and 0.903, respectively). SWV of the renal cortex at a depth of <4 cm was significant higher than that at a depth of >4 cm. Regardless of the subtypes of RCC, SWV and SWR of RCCs differed significantly from those of AMLs (2.28±0.85 versus 1.98±0.85; 1.09±0.56 versus 0.78±0.34; p=0.045 and p<0.001, respectively). At cut-off points of SWV >1.87 m/s or SWR >0.84 to differentiate RCCs from AMLs, the sensitivity and specificity were 47.5%, 33.2% or 47.5%, 30.2%, respectively. When the subtypes of RCCs were taken into account, SWV and SWR of ccRCCs were significantly higher than those of pRCCs, cRCCs, and AMLs, while there was no significant difference among the latter. With SWV >1.98 m/s or SWR >0.80 as the cut-off point to differentiate ccRCCs from other renal tumours, the sensitivity and specificity were 69.8%, 65% or 76.8%, 73.4%, respectively.

The ARFI technique offers additional information regarding renal tumour elasticity with good reproducibility. SWV and SWR are potential biomarkers in this setting, helping to differentiate ccRCC from other renal tumour histotypes.