OptiCross HD IVUS for Assessing Invasion Depth in Upper Tract Urothelial Carcinoma

This is a prospective, single-center, single-arm, investigator-initiated exploratory device study conducted at Severance Hospital. Eligible participants are adults with UTUC diagnosed or strongly suspected on imaging and/or ureteroscopic biopsy for whom RNU has already been selected as the standard treatment. Participation does not change the planned operation.

After written informed consent and confirmation of eligibility, the OptiCross HD 60-MHz IVUS catheter is advanced over a 0.014-inch guidewire to the renal pelvis or ureteral lesion under endoscopic and fluoroscopic guidance during general anesthesia. A short manual or automated pullback is performed to acquire cross-sectional images of the lesion and adjacent upper urinary tract wall. The catheter is removed immediately after imaging, and the planned RNU is then performed.

IVUS images are reviewed independently by three specialists who did not participate in the procedure and are blinded to preoperative clinical information and final pathology. Each reviewer assigns an IVUS-based T stage and records whether the urothelium, muscularis, and adventitia can be distinguished, whether the lesion boundary is visualized, and whether image quality is diagnostically adequate. A majority interpretation from at least two of the three reviewers is used for the main concordance analysis.

The primary analysis compares IVUS-based T stage with the final pathologic pT stage from the resected specimen. Secondary analyses include technical success, visualization of the three wall layers, lesion-boundary clarity, inter-reviewer agreement, and device- or procedure-related adverse events. Safety is assessed during the procedure, during hospitalization, at approximately 4 weeks, and at the final follow-up approximately 3 months after surgery.