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Background: Several intraoperative vascular imaging techniques can potentially aid the surgeon’s clinical assessment of mastectomy skin flap (MSF) perfusion and help to predict areas of future necrosis. Currently, there are no head to head studies directly comparing these alternative methods. We hypothesized that: 1) Laser-Assisted Indocyanine Green (ICG) and Fluorescein Dye Angiography are more sensitive methods of predicting mastectomy skin flap necrosis than clinical assessment, and 2) Laser-Assisted ICG Dye Angiography is a more specific predictive tool than Fluorescein Dye Angiography.
Methods: A prospective pilot study of 50 immediate breast reconstructions with tissue expander/implant or autologous flap is currently underway. All MSFs are evaluated intraoperatively via clinical assessment, ICG Dye Angiography (Novadaq SPY System) and Fluoroscein Dye Angiography following expander placement or flap inset. The predicted area of necrosis by each method is clearly marked on the patient’s skin, traced onto a transparent film, and photodocumented. Only the areas predicted to become necrotic as per clinical assessment are excised. Patients are followed for the incidence of necrosis weekly until expander exchange for a permanent prosthesis. Areas of necrosis are then directly compared to areas predicted by the three intraoperative methods.
Results: Intraoperative imaging has been completed for 10 immediate breast reconstructions (7 patients), with a mean follow-up time of 4.5 weeks (Range: 2-8). Patients enrolled to date have a mean age of 50.5 (Range: 40-76) and mean BMI of 26.3 (+/- 6.5). Clinical assessment, ICG, and Fluorescein Dye Angiography predicted mean areas of necrosis of 0.3, 6.2, and 22.7 cm2 respectively, though only two cases of necrosis occurred. One patient with a history of a mastopexy, diabetes, and tobacco use developed cellulitis two weeks post-operatively requiring admission for IV antibiotics. The patient subsequently developed full thickness MSF necrosis and underwent debridement at the 1-month post-operative clinic visit (Figure 1a). Intraoperative ICG predicted an area of low perfusion on the superior MSF that correlated closely with the area of actual necrosis, though over predicted necrosis on the inferior MSF(Figure 1b). Flourescein also over-predicted the area of eventual superior MSF necrosis, while clinical assessment failed to predict the area at all. A second patient with a history of tobacco use developed a small area of superficial necrosis that was not predicted by any of the three methods. On quantitative analysis (SpyQ), both patients had relative perfusion percentages less than 38% in the areas of necrosis. However, areas of lower perfusion percentages (29-31%) were identified on the same patients that did not turn necrotic.
Conclusions: Early results show a trend towards over prediction of necrosis by both ICG and Fluorescein Dye angiography, while clinical assessment failed to predict two cases of necrosis. By identifying a more effective, quantitative, minimally invasive method to detect post-mastectomy skin flap viability we hope to decrease the incidence of MSF necrosis and thereby decreased morbidity for breast cancer patients.