CA9 and nonpapillary renal cell carcinoma: The high tumor uptake of 124I-cG250 in ccRCC relies upon the constitutive high expression of CAIX in this tumor type, which results in high uptake of the radiotracer (7.4±1.8%ID/g at 7 days) and sufficient tumor/blood differential (ca 31) to provide optimal PET images [21].