Table 5.

Statistically significant (p < 0.05) FFT-based texture metrics identifying various renal mass subtypes

Performance of the FFT-metrics based on their AUC in segregating the various renal mass subtypes (p < 0.05)
Comparison	CECT phase	FFT predictor	AUC
Oncocytoma vs clear cell	Corticomedullary	CI	0.73, 95% CI, (0.62, 0.84)
Oncocytoma vs clear cell	Corticomedullary	E_FFT_Phase	0.71, 95% CI, (0.6, 0.82)
Oncocytoma vs clear cell	Excretory	Combined	0.81, 95% CI, (0.72, 0.9)
Oncocytoma vs clear cell	Excretory	E_FFT_Mag	0.78, 95% CI, (0.68, 0.88)
Oncocytoma vs lp-AML	Nephrographic phase	Combined	0.77, 95% CI, (0.63, 0.92)
Oncocytoma vs lp-AML	Nephrographic phase	E_FFT_Mag	0.76, 95% CI, (0.61, 0.91)
Oncocytoma vs lp-AML	Excretory	Combined	0.83, 95% CI, (0.71, 0.95)
Malignant vs benign	Excretory	Combined	0.80, 95% CI, (0.73, 0.88)
Malignant vs benign	Excretory	E_FFT_Mag	0.73, 95% CI, (0.65, 0.81)

CECT, contrast-enhanced CT; CI, complexity index ; FFT, fast Fourier transform; lp-AML, lipid-poorangiomyolipoma; RCC, renal cell carcinoma.

Combined: E_FFT_Mag + E_FFT_Phase + CI. FFT-based metrics that provided AUC > 0.7 have been tabulated. A cutoff of AUC > 0.7 has used based on similar peer-reviewed studies in the literature. The combinedmetric of E_FFT_Mag, E_FFT_Phase and CI showed the best performance AUC > 0.8 insegregating oncocytoma from clear cell RCC and lipid-poor AML and also, insegregating benign renal masses comprising (oncocytoma and lipid-poor AML) from malignant renal masses comprising (clear cell RCC, papillary RCC andchromophobe). Values in the AUC column are reported in the following format: (AUC, confidence level, AUC range). The FFT predictors with the three highest AUC values have been highlighted in bolded text.