The Use of Laser-Assisted Indocyanine Green Dye Angiography to Predict Mastectomy Skin Flap Viability

Overview

In the investigators previous study of 51 breast reconstructions (32 patients), we compared three different assessments of vascular perfusion of tissue; clinical judgment, fluorescein dye angiography (FDA) and laser-assisted indocyanine green dye angiography (ICG). Because tissue with poor perfusion becomes necrotic and can compromise the success of breast reconstruction, it is important that tissue with poor perfusion be removed at the time of the reconstructive surgery. However, it is also important to remove the least amount of potentially necrotic tissue as possible so that the breast reconstruction is not compromised by lack of skin. Therefore finding the best way to assess potentially necrotic tissue is a vital clinical question. In the initial study the 3 different assessment methods which were made at the time of surgery were compared to the subsequent development of necrotic tissue. In the initial study, clinical judgment was the basis for determining the tissue removed because it had the potential to become necrotic. The investigators collected data with the FDA system and ICG system, but this data was not used in making the clinical decisions. The study followed the progression of tissue to overt necrosis and this clinical outcome was then compared to the predictions made by the three different assessment strategies. The investigators found that clinical judgment failed to detect tissue which subsequently became necrotic in 21 out of 51 instances for a failure rate of 41%. The FDA system predicted larger areas of potentially necrotic tissue than clinical judgment, but was found to over-predict the area that became necrotic by 82% - 88% (88% if all cases were included and 82% if only those cases which subsequently developed necrosis were included). Although the ICG system is similar to the FDA system in that a dye is used to assess perfusion, the ICG system has enhanced software which improves the estimated perfusion. The ICG system provided 90% sensitivity and 100% specificity in the predicted vs. actual necrotic tissue at specific absolute perfusion units values. Hypothesis: Using the values of absolute perfusion units discovered in the previous study and implementing its use in the operating room will decrease all-inclusive necrosis rates to below 10%, reflecting a 31% decrease in the investigators necrosis rate.

The investigators current rate of the development of all-inclusive mastectomy skin necrosis was approximately 41%. This means that current methods of clinical assessment fail to identify regions of mastectomy skin with poor blood flow that lead to necrosis in 41% of patients. The investigators know that using the SPY imaging system is more sensitive for necrosis than clinical assessment. With SPY Q analysis the investigators hope to obtain 90% sensitivity, 100% specificity at absolute perfusion unit values identified in the previous study. The investigators do not anticipate obtaining a 0% all-inclusive necrosis rate but do believe they can eliminate all clinically significant necrosis that would result in operative debridement or removal of implant. The less severe forms of necrosis including epidermolysis and incisional necrosis are self-limiting and usually do not require invasive interventions.