Evaluating visual perception for assessing reconstructed flap health.
BACKGROUND
Detecting failing tissue flaps before they are clinically apparent has the potential to improve postoperative flap management and salvage rates. This study demonstrates a model to quantitatively compare clinical appearance, as recorded via digital camera, with spatial frequency domain imaging (SFDI), a noninvasive imaging technique using patterned illumination to generate images of total hemoglobin and tissue oxygen saturation (stO2).


METHODS
Using a swine pedicle model in which blood flow was carefully controlled with occlusion cuffs and monitored with ultrasound probes, throughput was reduced by 25%, 50%, 75%, and 100% of baseline values in either the artery or the vein of each of the flaps. The color changes recorded by a digital camera were quantified to predict which occlusion levels were visible to the human eye. SFDI was also used to quantify the changes in physiological parameters including total hemoglobin and oxygen saturation associated with each occlusion.


RESULTS
There were no statistically significant changes in color above the noticeable perception levels associated with human vision during any of the occlusion levels. However, there were statistically significant changes in total hemoglobin and stO2 levels detected at the 50%, 75%, and 100% occlusion levels for arterial and venous occlusions.


CONCLUSIONS
As demonstrated by the color imaging data, visual flap changes are difficult to detect until significant occlusion has occurred. SFDI is capable of detecting changes in total hemoglobin and stO2 as a result of partial occlusions before they are perceivable, thereby potentially improving response times and salvage rates.
Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, California.
Adrien
A
Ponticorvo
Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, California.
Eren
E
Taydas
Modulated Imaging Inc., Beckman Laser Institute Photonic Incubator, Irvine, California.
Amaan
A
Mazhar
Department of Plastic Surgery, University of California Irvine Medical Center, Orange, California.
Christopher L
CL
Ellstrom
Department of Plastic Surgery, University of California Irvine Medical Center, Orange, California.
Jonathan
J
Rimler
Department of Plastic Surgery, University of California Irvine Medical Center, Orange, California.
Thomas
T
Scholz
Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, California.
June
J
Tong
Department of Plastic Surgery, University of California Irvine Medical Center, Orange, California.
Gregory R D
GR
Evans
Modulated Imaging Inc., Beckman Laser Institute Photonic Incubator, Irvine, California.
David J
DJ
Cuccia
Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, California. Electronic address: AJDurkin@yahoo.com.
Anthony J
AJ
Durkin
D000818:Animals; D015415:Biomarkers / Q000097:blood; D003118:Color Perception; D058752:Free Tissue Flaps / Q000098:blood supply* / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D061848:Optical Imaging; D010100:Oxygen / Q000097:blood; D010781:Photography; D013552:Swine
D015415:Biomarkers; D006454:Hemoglobins; D010100:Oxygen
Color perception; Flap reconstruction; Spatial frequency domain imaging