The Use Of Portable Hyperspectral Imaging In Assessing Random Pattern Surgical Flap Viability.
Victoria I. Prete, BS, SeungJu Oh, BA, Melissa McCarthy, MPH, Robert Slamin, BS, Angel Baez, MS, John Castle, MD, Mustafa Akyurek, MD PhD, Janice Lalikos, MD.
University of Massachusetts Medical School, Division of Plastic Surgery, Worcester, MA, USA.
Purpose: Hyperspectral Imaging (HSI) is used clinically to assess foot perfusion in diabetics at risk for vascular disease, therefore evaluation of skin flap viability appears to be an implicit potential application. Our preclinical study previously validated the use of HSI for early prediction of flap necrosis in a mouse model. This prospective analysis aims to: 1. establish normative values of oxyhemoglobin (OxyHb), deoxyhemoglobin (DeoxyHb), and oxygen saturation (O2 sat) of breast and nipple tissue, and 2. identify changes seen for breast tissue perfusion in random-pattern flaps.
Methods: Fifteen patients, twenty-four breasts, undergoing random pattern mastectomy skin flaps were recruited for the study. Average age of participants was 50.8(±11.0)-years-old. Reasons for surgery included prophylactic mastectomy (54%) or history of breast cancer requiring reconstruction with/without concomitant mastectomy (46%). Two breasts previously underwent radiation (8.3%). HSI images were taken at six time points using the HyperViewTM system: pre-operatively (control images), upon final suture placement (post-operative period zero (POP0)), post-operative day (POD) 1, POD2, POD14, and POD30. Perfusion data was obtained from the device for OxyHb and DeoxyHb (reported in arbitrary units (AU)), and percentage O2 sat. We analyzed values at four zones within the surgical site: 0-10mm and 10-20mm areas, above and below the suture line. Normative values for breast and nipple tissue were analyzed using a Student's t-test. Flap perfusion status was tracked over time using the three measured parameters. One-way ANOVA was used to compare means across the six time points and four zones. Outliers were maintained during analysis as they did not significantly alter the p-values and serve to illustrate the innate differences across patients post-operatively.
Results: Twenty-nine breasts were analyzed to obtain normative values for OxyHb, DeoxyHb and O2 Sat resulting in 53.4(±23.4)AU, 45.7(±18.1)AU, and 52.9(±14.3)% respectively in the nipple and 32.2(±16.8)AU, 35.5(±14.3)AU, and 46.62(±18.8)% respectively in the breast. Statistical analysis of the three post-operative perfusion parameters showed: significant (p of 1.033e-14) increase in OxyHb at POP0, wider variation in OxyHb values at POP0, and return to baseline by POP14. DeoxyHb showed no significant variation across time points (p of 0.5464). Oxygen saturation showed a significant (p of 0.0001726) increase from baseline to POP0 followed by a gradual decrease, O2 saturation was also significantly lower in the zone 10-20mm above the suture line (Figure 1).
Conclusions: The HyperViewTM system is portable, utilizes imaging spectroscopy within the visible light spectrum, and is completely non-invasive. It is a useful tool in the evaluation of at-risk skin perfusion. This is the first study to help understand its potential utility in random-pattern flaps in the setting of breast reconstruction. Analysis of tissue using HSI revealed an increase in post-operative levels of O2 Saturation and OxyHb in the immediate post-operative period with return to baseline by one-month post-op. We also established normative values for both breast and nipple tissue. HSI has promising utility in the field of plastic surgery.
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