To differentiate between hemorrhagic or proteinaceous cysts and RCC, a retrospective study shows that homogenous high T1 signal intensity lesions with smooth borders and lesion to renal parenchyma signal intensity ratio of >1.6 predicted the lesion as a benign cyst [53]. Another study of 144 T1-hyperintense lesions demonstrated that diffuse and marked T1-hyperintensity achieved accuracies of 73.6% to 79.9% for the diagnosis of T1-hyperintense cysts [54]. An angular interface with the renal parenchyma on T2- weighted imaging has been shown to be 78% sensitive and 100% specific for differentiating benign exophytic renal masses from malignant masses [55]. Diffusion-weighted imaging, although less accurate than contrast-enhanced MRI, may have some ability to differentiate solid RCC from oncocytomas and characterize the histologic subtypes of RCC [56]. New and specialized MRI sequences have been proposed for the purposes of characterizing the vascularity of renal lesions in patients with renal dysfunction. For example, one small study of 17 renal lesions used arterial spin labeling to detect blood flow in renal masses, which correlated with malignancy [57]. A drawback of MRI compared with CT is the limited ability of MRI for detection of calcifications. MRU There is no relevant literature regarding the use of MRU in the evaluation of indeterminate renal masses. Radiography Intravenous Urography There is no relevant literature regarding the use of IVU for the evaluation of indeterminate renal masses. IVU requires IV administration of iodinated contrast. US Abdomen with IV Contrast CEUS using microbubble agents is emerging as a useful way to characterize previously indeterminate renal lesions [16-18]. It is not limited by renal or hepatic failure.
Indeterminate Renal Mass. To differentiate between hemorrhagic or proteinaceous cysts and RCC, a retrospective study shows that homogenous high T1 signal intensity lesions with smooth borders and lesion to renal parenchyma signal intensity ratio of >1.6 predicted the lesion as a benign cyst [53]. Another study of 144 T1-hyperintense lesions demonstrated that diffuse and marked T1-hyperintensity achieved accuracies of 73.6% to 79.9% for the diagnosis of T1-hyperintense cysts [54]. An angular interface with the renal parenchyma on T2- weighted imaging has been shown to be 78% sensitive and 100% specific for differentiating benign exophytic renal masses from malignant masses [55]. Diffusion-weighted imaging, although less accurate than contrast-enhanced MRI, may have some ability to differentiate solid RCC from oncocytomas and characterize the histologic subtypes of RCC [56]. New and specialized MRI sequences have been proposed for the purposes of characterizing the vascularity of renal lesions in patients with renal dysfunction. For example, one small study of 17 renal lesions used arterial spin labeling to detect blood flow in renal masses, which correlated with malignancy [57]. A drawback of MRI compared with CT is the limited ability of MRI for detection of calcifications. MRU There is no relevant literature regarding the use of MRU in the evaluation of indeterminate renal masses. Radiography Intravenous Urography There is no relevant literature regarding the use of IVU for the evaluation of indeterminate renal masses. IVU requires IV administration of iodinated contrast. US Abdomen with IV Contrast CEUS using microbubble agents is emerging as a useful way to characterize previously indeterminate renal lesions [16-18]. It is not limited by renal or hepatic failure.