Quantitative assessment of perfusion and vascular compromise in perforator flaps using a near-infrared fluorescence-guided imaging system.
BACKGROUND
Techniques currently used to determine flap perfusion are mainly subjective, with the majority of reconstructive surgeons still relying on clinical examination. In this study, the authors demonstrate the use of near-infrared fluorescence angiography to directly quantify normal and abnormal perfusion in perforator flaps.


METHODS
Indocyanine green was injected intravenously into anesthetized adult pigs (n = 38). A custom near-infrared fluorescence imaging system was used for image acquisition and quantitation. Thirty-nine flaps were designed based on identified perforators, and postoperative imaging was performed for comparison. In select flaps, isolated occlusion of the arterial and venous pedicle was performed. In select flaps, vascular spasm was induced by local irrigation of the vessels with epinephrine. The fluorescence intensities of select regions of interest were quantified. From these data, the authors defined two indices for abnormal perfusion: the Tmax ratio and the drainage ratio.


RESULTS
The authors identified a normal pattern of perfusion before flap elevation, composed of a distinct fluorescence intensity peak at maximal arterial inflow followed by a smooth drop representing venous drainage. Delay of this peak after flap elevation, as indicated by the Tmax ratio, identified vascular spasm and arterial occlusion (p < 0.0001). Abnormal fall of fluorescence intensities after this peak, as indicated by the drainage ratio, identified venous occlusion (p < 0.0001).


CONCLUSIONS
Quantitation of fluorescence intensities by near-infrared angiography accurately characterizes arterial and venous compromise. The authors' technique can assess perfusion characteristics during the intraoperative and postoperative periods and therefore complements clinically based subjective criteria now used for flap assessment.
Matsui
Aya
A
Boston, Mass.; and Sapporo, Japan From the Division of Hematology/Oncology, Department of Medicine, the Department of Radiology, and the Department of Surgery, Division of Plastic and Reconstructive Surgery, Beth Israel Deaconess Medical Center; the Division of Cancer Diagnostics and Therapeutics, Hokkaido University Graduate School of Medicine; and the Department of Surgery, Brigham & Women's Hospital.
Lee
Bernard T
BT
Winer
Joshua H
JH
Laurence
Rita G
RG
Frangioni
John V
JV
D000465:Algorithms; D000818:Animals; D004396:Coloring Agents; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods; D007091:Image Processing, Computer-Assisted; D007208:Indocyanine Green; D013524:Surgical Flaps / Q000098:blood supply*; D013552:Swine
D004396:Coloring Agents; D007208:Indocyanine Green