Evaluation of microvascular anastomosis using real-time, ultra-high-resolution, fourier domain doppler optical coherence tomography

Background: Evolution in microsurgical techniques and tools has paved the way for supermicrosurgical anastomoses, with vessel diameters often approaching below 0.8 mm in the clinical realm and even smaller (0.2 to 0.3 mm) in murine models. Several imaging and monitoring devices have been introduced for postoperative monitoring, but intraoperative guidance, assessment, and predictability have remained limited to binocular optical microscopy and the surgeon's experience. The authors present a high-resolution, real-time, three-dimensional imaging modality for intraoperative evaluation of luminal narrowing, thrombus formation, and flow alterations. Methods: An imaging modality that provides immediate, in-depth, high-resolution, three-dimensional structure view and flow information of the anastomosed site, called phase-resolved Doppler optical coherence tomography, was developed. Twenty-two mouse femoral artery anastomoses and 17 mouse venous anastomoses were performed and evaluated. Flow status, vessel inner lumen three-dimensional structure, and early thrombus detection were analyzed based on imaging results. Predictions formed correlated with actual long-term surgical outcomes. Eventually, four cases of mouse orthotopic limb transplantation were carried out, and predicted long-term patency based on imaging results was confirmed by actual results. Results: The assessments based on high-resolution three-dimensional visualization of the vessel flow status and inner lumen provided by phase-resolved Doppler optical coherence tomography show 92 percent sensitivity and 90 percent specificity for arterial anastomoses and 90 percent sensitivity and 86 percent specificity for venous anastomoses. Conclusions: Phase-resolved Doppler optical coherence tomography is an effective evaluation tool for microvascular anastomosis. It can predict the long-term vessel patency with high sensitivity and specificity.