Use of near-infrared fluorescence angiography with indocyanine green to evaluate direct cutaneous arteries used for canine axial pattern flaps

Abstract

Objective: To describe the use of near-infrared angiography (NIRFA) to identify the vascularization of three canine axial pattern flaps (APFs) omocervical (OMO), thoracodorsal (THO), and caudal superficial epigastric (CSE); to establish a vascular fluorescence pattern (VFP) grading system; and to evaluate the effect of NIRFA on surgeon flap dimension planning compared to traditional landmark palpation (LP) and visualization assessments.

Study design: Experimental study.

Animals: A total of 15 healthy, client-owned dogs.

Methods: Dogs were sedated and flap sites were clipped. LP-based margins were drawn and preinjection images were recorded. Indocyanine green (ICG) was administered and VFP images were recorded. VFP scores were determined by five surgeons. Margin alterations were performed based on NIRFA-ICG images. Altered measurements were compared between LP and NIRFA-ICG images.

Results: Vascularization of the CSE flap was most visible with NIRFA with VFP scores 4/4 for 13/15 dogs. Intersurgeon agreement for VFP grades was poorest for THO (ICC = 0.35) and intermediate for OMO (ICC = 0.49) flaps. Surgeons were more likely to adjust dimensions for CSE flaps relative to OMO (OR 17.3, 95% CI: 6.2, 47.8) or THO (25.5; 8.6, 75.7).

Conclusion: Using a grading system, we demonstrated that the CSE flap was most visible. Surgeons were more likely to adjust the LP-CSE flap margins based on fluorescence patterns and were more likely to rely on LP when visualization scores were low.

Clinical significance: NIRFA has possible applications identifying some direct cutaneous arteries of APFs and their associated angiosomes in real-time. Further investigation is indicated to study NIRFA's potential to improve patient specific APF planning.