Intraoperative Doppler Ultrasonography with Superb Microvascular Imaging for Intestinal Perfusion Assessment in...

Intraoperative indocyanine green fluorescence imaging (ICG-FI) reduces anastomotic leakage, but has limitations related to contrast agent use, repeatability, and timing-dependent interpretation. We conducted an exploratory trial of a Doppler ultrasonography method using a high-frequency probe with superb microvascular imaging (SMI) to assess intestinal perfusion during colorectal cancer surgery.

In this single-center prospective pilot study, we enrolled patients undergoing colorectal cancer resection with anastomosis. Intraoperatively, SMI assessed intramural microvascular flow to determine the perfusion boundary, followed by ICG-FI. The SMI boundary was defined as the line where vertical vessels penetrating the muscularis propria were no longer visible. The primary endpoint was the difference in blood flow boundaries between ICG-FI and SMI. The secondary endpoints were inter-observer reproducibility of SMI boundary identification and safety within 30 days.

Seven patients were analyzed for efficacy (one excluded because of invalid SMI data) and eight for safety. The median difference in blood flow boundaries between ICG-FI and SMI was -4 mm (range, -60 to 0 mm), with SMI identifying a more proximal boundary. Inter-observer variability for SMI boundary detection showed a median absolute difference of 2 mm (range, 0-4 mm). No procedure-related adverse events occurred.

Our findings revealed differences in perfusion boundary location between SMI and ICG-FI, and intraoperative SMI acquisition and boundary identification were technically feasible. Analyzable data were obtained in seven of eight patients, with high inter-observer reproducibility and no procedure-related adverse events. Further prospective validation with standardized SMI acquisition and interpretation is required before clinical implementation.