Radiomics-based machine learning role in differential diagnosis between small renal oncocytoma and clear cells carcinoma on contrast-enhanced CT: A pilot study.

Purpose: To investigate the potential role of radiomics-based machine learning in differentiating small renal oncocytoma (RO) from clear cells carcinoma (ccRCC) on contrast-enhanced CT (CECT). Material and methods: Fifty-two patients with small renal masses who underwent CECT before surgery between January 2016 and December 2020 were retrospectively included in the study. At pathology examination 39 ccRCC and 13 RO were identified. All lesions were manually delineated unenhanced (B), arterial (A) and venous (V) phases. Radiomics features were extracted using three different fixed bin widths (bw) of 25 HU, 10 HU, and 5 HU from each phase (B, A, V), and with different combinations (B+A, B+V, B+A+V, A+V), leading to 21 different datasets. Montecarlo Cross Validation technique was used to quantify the estimator performance. The final model built using the hyperparameter selected with Optuna was trained again on the training set and the final performance evaluation was made on the test set. Results: The A+V bw 10 achieved the greater median (IQR) balanced accuracy considering all the models of 0.70 (0.64-0.75), while A bw 10 considering only the monophasic ones. The A bw 10 model achieved a median (IQR) sensitivity of 0.60 (0.40-0.60), specificity of 0.80 (0.73-0.87), AUC-ROC of 0.77 (0.66-0.84), accuracy of 0.75 (0.70-0.80), and a Phi Coefficient of 0.38 (0.20-0.47). None of the nine models with the lowest mean balanced accuracy values implemented features from A. Conclusion: The A bw 10 model was identified as the most efficient mono-phasic model in differentiating small RO from ccRCC.