Intraoperative Hemifacial Composite Flap Perfusion Assessment Using Spatial Frequency Domain Imaging

Abstract

Background Vascularized composite allotransplantation (VCA) represents an important advancement in the field of reconstructive microsurgery and has continued to increase in popularity. The significant clinical morbidity associated with flap failure represents an important barrier to even more widespread use of these techniques. Early identification of vascular compromise has been associated with a higher salvage rate, yet most surgeons rely only on clinical assessment intraoperatively. Spatial frequency domain imaging (SFDI) presents a non-contact, objective measurement of tissue oxygenation over a large field of view. This study aims to evaluate the use of SFDI technology in hemifacial composite flap compromise as could occur during facial transplant. Methods Six composite hemifacial flaps were created in three 35 kg Yorkshire pigs and continuously imaged using SFDI before, during, and after 15-minute selective vascular pedicle occlusion. Arterial and venous clamping trials were performed for each flap. Changes in oxyhemoglobin concentration (ctO2Hb), deoxyhemoglobin concentration (ctHHb), and total hemoglobin (ctHbT) were quantified over time. Results SFDI successfully measured changes in oxygenation parameters in all six composite tissue flaps. Significant changes in ctO2Hb, ctHHb, and ctHbT were seen relative to controls. Early and distinct patterns of alteration were noted in arterial and in venous compromise relative to one another. Conclusions The need for non-invasive, reliable assessment of composite tissue graft viability is apparent, given the morbidity associated with flap failure. The results of this study suggest that SFDI technology shows promise in providing intraoperative guidance with regard to pedicle vessel integrity during reconstructive microsurgery.

Vascularized composite allotransplantation: a closer look at the banff working classification

“…Obtaining deeper biopsies and/or obtaining imaging have been proposed as a method to evaluate larger vessels and for the significance of deep inflammatory infiltrates in the absence of visual changes of rejection. In VCA, the use of noninvasive vascular imaging techniques for perfusion is being investigated . The role of noninvasive vascular imaging in monitoring for or evaluating rejection in VCA is undefined, although it may have some promise in other areas of transplantation.…”

Spatial frequency domain imaging in 2019: principles, applications, and perspectives

“…Multiple groups have demonstrated the feasibility of SFDI to measure ischemic onset in a number of organs: including skin flaps, 14,101-104 kidney, 105 bowel, 14 liver, 14 and facial transplants. 106 These studies have served as benchmarks to establish validity, sensitivity, and clinical relevance of SFDI oxygenation and hemoglobin measurements. It was first demonstrated in 2011 that oxygenation measurements trends using SFDI during an occlusion matched trends measured by FDAcleared oximeter devices.…”

“…101 Beyond the diagnostic potential of oxygenation imaging, it was also demonstrated that the source of the occlusion (arterial versus venous) could be identified as early as 2 min after blockage in a hemifacial composite flap transplants. 106 Published clinical data using SFDI have been limited. A first-in-human pilot study involving three patients established the capability of SFDI to work under the constraint of flap transplantation surgeries.…”

Single snapshot of optical properties image quality improvement using anisotropic two-dimensional windows filtering

“…[1][2][3][4][5][6] Some medical fields in particular, such as surgery, are driving this need for realtime interpretable information content to aid decision-making in a time-constrained environment. [7][8][9][10][11][12] Several solutions have been investigated to fulfill this need, each with their pros and cons, ranging from raster scanning of microscopic information to wide-field acquisitions of diffused information. 13,14 For instance, fluorescence imaging to help surgeons visualizing structures of interest, such as lymph nodes, ureters, or micrometastasis, stands as an example where providing tissue-related information in real time plays a key role in clinical adoption.…”