PET/CT in renal and bladder cancers

Abstract

FDG is the most frequently used positron emission tomography probe but it has certain limitations when used in urological cancers due to its urinary elimination, which prevents the proper visualization of the bladder and kidneys. The introduction of co-registered PET and computed tomography (PET/CT) represents a major advance in technology and now become the new standard for many cancers. For the staging and surveillance of renal cell cancer, FDG PET/ CT had results that were at least as good as conventional methods, which are potentially harmful for the remained renal function. FDG-PET/CT is able to evaluate early response to sunitinib or sorafenib treatment in metastatic renal cell cancer. An early decrease in the mean glucose uptake was found in both soft and skeletal lesions after treatment, thus PET seems to be more advantageous compared with RECIST evaluation. In addition, the survival of patients with advanced renal cell cancer can be predicted by evaluating their SUVmax using FDG-PET/CT. Although urinary bladder cancer demonstrates sufficiently increased FDG uptake, primary tumors are difficult to identify due to the renal excretion of FDG. The accuracy of FDG-PET/CT in metabolically active metastases is generally higher when compared to conventional CT except for identifying small lung deposits. PET/CT with delayed images after a diuretic and oral hydration may improve detection of locally recurrent or residual UBC and could replace standard CT and bone scintigraphy in the presurgical staging and monitoring of patients with urinary bladder cancer. 18F-choline PET may be useful for staging of urinary bladder cancer in addition to FDG PET.