This pilot study is designed to evaluate imaging parameters indicative of underlying tumor biology. Patients with large renal masses (>3 cm, or at the discretion of the investigator) who are planning to undergo nephrectomy will be identified, and recruited to undergo a contrast-enhanced magnetic resonance-Fluorodeoxyglucose-positron emission tomography (MR-FDG-PET) scan.

This pilot study is designed to evaluate imaging parameters indicative of underlying tumor biology. Patients with large renal masses (>3 cm, or at the discretion of the investigator) who are planning to undergo nephrectomy will be identified, and recruited to undergo a contrast-enhanced magnetic resonance-Fluorodeoxyglucose-positron emission tomography (MR-FDG-PET) scan. Samples collected from their tumor after it is removed will undergo a variety of laboratory tests, including biomarker assessments and genotyping. By examining primary renal masses via a combination of MR and FDG-PET functional imaging in concert with tissue based tests, areas of hypermetabolism and hypervascularization will be evaluated as features of HIF activation or tumor subtype.

Inclusion Criteria:

• ≥ 18 years of age (no upper age limit)
• Informed consent obtained and signed
• Clinically suspected RCC based on imaging performed prior to enrollment
• Planned nephrectomy schedule that can accommodate a MR-FDG-PET scan within 4 weeks prior to surgery
• Willing to undergo gadolinium enhanced MRI with simultaneous acquisition of FDG-PET uptake by the tumor within 4 weeks prior to nephrectomy
• Willing to consent for genetic and proteomic analysis of tumor and germline nucleic acids
• Women of childbearing potential must have a negative serum or urine pregnancy test performed within 7 days prior to FDG-PET-MRI
• Breast feeding women cannot do so for 24 hours after FDG injection
• Patient is willing to fast for 4 hours, including avoiding any sugar-containing drinks.
• Patient is willing to drink at least 32 ounces of water (or other no-sugar-containing fluids) within 4 hours prior to arriving for scans.

Exclusion Criteria:

• History of severe reaction to gadolinium-enhanced MRI
• Poorly controlled diabetes mellitus
• Inability to tolerate PET and/or MRI
• Presence of pacemaker or intracranial aneurysm clip
• GFR < 30mL/min as measured via Cockcroft-Gault equation
• Inability to lie flat for >1 hour
• Pregnant female
• History of a prior malignancy within past 5 years are excluded unless they have been disease free for 3 or more years or unless they have a completely resected non-melanoma skin cancer, low risk prostate cancer, or other low risk tumor history at the discretion of the investigator.
• Substance abuse, medical, psychological, or social conditions that may interfere with the patient's participation in the study