Endoluminal Ultrasound for Upper Tract Urothelial Carcinoma

Accurate clinical staging of UTUC remains elusive, and relies heavily on ureteroscopic biopsy grade and other findings as surrogates for predicting final pathologic stage. Endoluminal ultrasound (ELUS) has been used in vascular and nonvascular applications dating back almost 40 years. For the upper tract a small experience has been building. ELUS of the upper tract visualizes primarily the muscularis layer of the ureter, which is seen as a hypoechoic symmetric rim, with the periureteral fat seen beyond it, visualized as a very bright hyperechoic layer. UTUC tumors are seen as hypoechoic masses that are either intraluminal or cause bulging of the collecting system. Invasive disease is suspected when an irregular hypoechoic mass extends into or beyond the muscularis layer and disrupts the hyperechoic layer of periureteral fat. Several limitations remain with ELUS, including probe size and inability to direct the transducer into the mid-or lower calyces. However, a few small, retrospective, single center experiences with small numbers of patients have shown the potential for this modality to improve clinical staging. Any modality that may help better stratify patients to endoscopic management, nephroureterectomy alone, or initial neoadjuvant chemotherapy, deserves further study. Larger multi-institutional efforts will be needed to acquire the data to further characterize the benefits of ELUS for staging of UTUC.