Diagnostic imaging for renal masses of unknown nature using conventional imaging modalities such as 3 phase contrast-enhanced computed tomography (CT) is not always conclusive. After (partial) nephrectomy, 10-20 % of the resected tumors show benign histology which could not be identified on diagnostic imaging. With improved imaging techniques available, leading to improvements in characterisation of renal tumors, the number of unnecessary resections may be reduced. The objective of this study is to assess the ability to discriminate oncocytoma from RCC based on the ADC distribution parameters with addition of, tumor volume, and patient demographic characteristics.

Inclusion Criteria:

• Radiologic diagnosis of renal tumor based on previous ultrasonography, CT or MRI examinations.
• Signed Institutional Review Board (IRB) approved informed consent form.
• Being at least 18 years of age.
• Histopathologically confirmed renal tumor diagnosis.

Exclusion Criteria:

• Relative contra indications for MRI (metal device/foreign bodies, claustrophobia);
• Active renal or perirenal infection;
• Minor and/or incapacitated adult.

Patients >18 years of with a histopathologically confirmed renal tumor diagnosis.