Feasibility of Spectral Computed Tomography Color Overlay to Augment Tumor Visibility for Renal Cryoablation

This study aims to assess a spectral computed tomography (CT) color overlay technique for augmenting the visualization of endophytic renal tumors during percutaneous thermal ablation procedures.

This retrospective study consisted of renal cryoablation procedures from June to December 2023. Of the 68 renal ablations with spectral results archived, 27 cases were assigned majority endophytic. Two radiologists reviewed and rated two series for each case: a conventional non-contrast CT series and an electron density color overlay series. Tumor conspicuity was evaluated on a continuous sliding scale. Subsequently, radiologists determined whether percutaneous ablation could proceed based on visualization using the conventional non-contrast CT series alone, using the color overlay series, or if additional contrast-enhanced CT was necessary for optimal guidance. Statistical assessment was performed using a two-sided Wilcoxon signed-rank test with a significance level of p = 0.01.

There was a significant (p < 0.001) improvement in endophytic tumor conspicuity with the electron density fusion series (Median: 36.3) compared to the conventional CT series (Median: 19.2). When evaluating adequacy of tumor visualization for procedural planning, readers were more likely to agree when reviewing the electron density color overlay series (44% of reads; 22/50) rather than the conventional CT series (22% of reads; 11/50).

Spectral CT color overlay improved visibility of endophytic renal tumors compared to conventional CT alone. This highlights the benefit of a low-noise, narrow-window color overlay for augmenting lesion localization. LEVEL OF EVIDENCE 3: Level 3, retrospective study.