Imaging and Management of Incidental Renal Lesions

Table 2

Nodular solid lesions (“ball” type).

Type	Common diagnosis	CT	MRI
Benign	AML	(i) Macroscopic fat tissue at unenhanced CT; (ii) No calcifications	(i) T1 hyperintense; (ii) T2 hypointense; (iii) India-ink artifact at the interface between the mass and the renal parenchyma (intracellular fat)
Indeterminate	Oncocytoma	(i) Homogeneous intravascular pattern; (ii) Central scar; (iii) Segmental inversion enhancement pattern	(i) Not specific: usually T1-hypointensity and T2-hyperintensity; (ii) Scar: T2 hyperintense; (iii) High signal on ADC
Malignant	RCC	(i) Hypervascularity (cc-RCC); (ii) Hypovascularity (p-RCC, ch-RCC); (iii) Homogeneous peripheral enhancement (p-RCC); (iv) Moderate enhancement (ch-RCC)	(i) T1 isointense and T2 hyperintense (cc-RCC); (ii) T1 hyperintense and T2 hypointense (p-RCC and ch-RCC)