PET/MR for Characterization of Renal Masses (RMs)

The frequency of kidney tumors found incidentally on imaging studies performed for unrelated reasons continues to increase leading to more surgeries and ablations for the treatment of renal masses thought to be cancer. However, about 20% of these masses are not cancerous and do not require treatment. Many cancerous kidney tumors are indolent and can be followed safely with imaging (i.e., particularly tumors \<2 cm and in patients with limited life expectancy), while some tumors are both malignant and aggressive, with a higher potential to spread outside the kidney and require treatment. The purpose of this observational study is to assess the ability of Fludeoxyglucose (18F) (FDG) PET/MR to distinguish different types of kidney tumors. The investigators hypothesize that PET/MR will better show differences between aggressive and both indolent and benign kidney masses compared to the currently used radiologic scans. Participants will be selected from those who have been scheduled to receive a contrast-enhanced MRI for their regular care due to a suspicious kidney mass. Participants will have their MRI on a hybrid PET/MR scanner capable of obtaining both MRI and PET images. While they are receiving their standard of care MRI exam, patients will also receive a research FDG PET exam. Participants will have an IV placed for administration of the MRI contrast agent, just as they would if they were not taking part in the study. The same IV will be used to give the FDG radiopharmaceutical for the PET scan and furosemide (a diuretic), to help empty the bladder before the scan and help better see the kidneys on the scans. Both FDG and furosemide are FDA approved medications. Participants will have only one visit with the research team which will last \~2.5 hours and will include collection of the participant's regularly scheduled MRI. If participants undergo surgery to remove the tumor, the study will collect samples of the removed tissue for research. If participants receive a biopsy of the tumor, the study may collect an additional sample of the tumor for research. After the PET/MRI, participants will not have additional visits with the study team, but the study team may call every 6-12 months for up to 2 years to see how they are doing and ask about their health. The study team will review the medical record for any changes to their diagnosis, updates to their medical history, new scans ordered by their regular doctor, or recent lab or biopsy results.