Although MRI of the abdomen can be useful for characterization and follow-up of small localized renal masses undergoing active surveillance, the benefit of imaging the pelvis during surveillance has not yet been defined and is considered optional in the guidelines [2,9,11]. There is no relevant literature regarding the use of MRI of the pelvis in the follow-up of patients on active surveillance, although data from 2 retrospective studies evaluating RCC staging with CT suggested that imaging of the pelvis had limited benefit for the detection of metastases [33,34]. Furthermore, metastatic progression occurs infrequently in patients on active surveillance with T1a renal masses [8,75-78,81,82]; therefore, MRI of the abdomen is preferred over MRI of the abdomen and pelvis. MRI Head Most patients with metastases to the central nervous system are symptomatic. Thus, active surveillance protocols for small localized renal masses have not supported routine imaging of the brain to search for metastases in asymptomatic patients. Brain imaging should be performed only in cases with suggestive signs or symptoms [2,9,11]. MRU There is no relevant literature regarding the use of MRU in the surveillance of small localized renal masses, and this method is not recommended by the guidelines [2,9,11]. US Kidney Retroperitoneal US of the kidney is an acceptable imaging modality for follow-up of small localized renal masses on active surveillance, especially once the growth rate of the renal mass has been established with CT or MRI [2,9,11,78]. US is an excellent method for characterizing cystic lesions and often provides supplementary information to the other imaging modalities. However, unenhanced US has an overall diagnostic accuracy for characterizing renal masses of only 30% [88].
Post Treatment Follow up and Active Surveillance of Renal Cell Carcinoma. Although MRI of the abdomen can be useful for characterization and follow-up of small localized renal masses undergoing active surveillance, the benefit of imaging the pelvis during surveillance has not yet been defined and is considered optional in the guidelines [2,9,11]. There is no relevant literature regarding the use of MRI of the pelvis in the follow-up of patients on active surveillance, although data from 2 retrospective studies evaluating RCC staging with CT suggested that imaging of the pelvis had limited benefit for the detection of metastases [33,34]. Furthermore, metastatic progression occurs infrequently in patients on active surveillance with T1a renal masses [8,75-78,81,82]; therefore, MRI of the abdomen is preferred over MRI of the abdomen and pelvis. MRI Head Most patients with metastases to the central nervous system are symptomatic. Thus, active surveillance protocols for small localized renal masses have not supported routine imaging of the brain to search for metastases in asymptomatic patients. Brain imaging should be performed only in cases with suggestive signs or symptoms [2,9,11]. MRU There is no relevant literature regarding the use of MRU in the surveillance of small localized renal masses, and this method is not recommended by the guidelines [2,9,11]. US Kidney Retroperitoneal US of the kidney is an acceptable imaging modality for follow-up of small localized renal masses on active surveillance, especially once the growth rate of the renal mass has been established with CT or MRI [2,9,11,78]. US is an excellent method for characterizing cystic lesions and often provides supplementary information to the other imaging modalities. However, unenhanced US has an overall diagnostic accuracy for characterizing renal masses of only 30% [88].