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.

Inclusion criteria

• Adults aged 19 years or older, male or female.
• UTUC diagnosed or strongly suspected based on preoperative CT or MRI and ureteroscopic biopsy.
• A lesion identified on imaging for which the depth of invasion is difficult to determine and surgery is considered necessary.
• RNU has been definitively selected by the treating physician, allowing direct comparison of IVUS findings with postoperative pathology.
• Upper urinary tract anatomy permits safe passage of the 3.1-F IVUS catheter to the lesion.
• Ability and willingness to provide written informed consent.

Exclusion criteria

• Ureteral stricture, severe angulation, congenital anomaly, or other anatomy that prevents safe catheter advancement.
• Definite distant metastasis (M1) or adjacent-organ invasion (T4) on imaging.
• Active urinary tract infection or uncontrolled coagulopathy that increases the risk of ureteroscopic manipulation.
• Pregnancy or breastfeeding.
• Any systemic condition or other circumstance judged by the investigator to make participation inappropriate or to interfere with interpretation of the study results.