Contrast Enhancement Early after Renal Malignancy Cryoablation: Imaging Findings Associated with Benignity.

Contrast enhancement by MRI done early after cryoablation for renal malignancies may suggest residual tumor (RT). However, we have observed MRI enhancement within 48 h of cryoablation in patients who had no contrast enhancement 6 weeks later. Our purpose was to identify features of 48-h contrast enhancement in patients without RT. This single-center retrospective study included consecutive patients who underwent percutaneous cryoablation of renal malignancies in 2013–2020, exhibited cryoablation-zone MRI contrast enhancement 48 h later, and had available 6-week MRI scans. Persistent or growing CE at 6 weeks vs. 48 h was classified as RT. A washout index was calculated for each 48-h MRI, and its performance for predicting RT was assessed by receiver operating characteristic curve analysis. We included 60 patients with 72 cryoablation procedures and 83 cryoablation zones exhibiting 48-h contrast enhancement; mean age was 66 ± 17 years. Clear-cell renal cell carcinoma accounted for 95