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Reply: Detection of Perforators Using Smartphone Thermal Imaging

Hardwicke, Joseph T. Ph.D., F.R.C.S.(Plast.); Skillman, Joanna M. F.R.C.S.(Plast.)

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Plastic and Reconstructive Surgery: November 2016 - Volume 138 - Issue 5 - p 940e
doi: 10.1097/PRS.0000000000002719
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We would like to thank Drs. Weum, Lott, and de Weerd for their comments on our recently published Ideas and Innovations article.1 As stated in our article, we did in fact use a modification of dynamic thermal imaging, which we have simplified to allow ease of use in the office setting. Images were recorded after a period of 3 minutes’ exposure at room temperature to allow a more gentle surface cooling, thus exposing the “hotspots” that may signify the presence of a perforator, rather than “forced” active cooling followed by intrinsic rewarming. In other pilot studies that we have performed, we have used a “cold challenge” by way of conductive, evaporative, or convective surface cooling. We have found that dynamic images collected in this way take longer and do not add significantly to the overall result. We have also found that patients may not be happy to undergo a cold challenge during their clinical consultation or preoperative assessment. It is possible that the use dynamic cooling of a raised perforator flap in the intraoperative setting could lead to an increase in operating room time and an increase in infective complications. A cold challenge may be better suited to the research environment rather than in the preoperative, intraoperative, and postoperative settings.

The perfusion of the raised flap is also a dynamic phenomenon. When the warm well-perfused area of a fasciocutaenous or musculocutaneous flap is delineated either by thermography or by simply using a “back-of-the-hand” clinical examination for a temperature change, we agree the discarded tissue could have been viable because of the dynamism of the perforasome. Of course, because it may take hours for this to develop, it is impractical in the free tissue transfer setting and, as such, a combination of clinical judgment and imaging adjuncts can be used to give the best estimation of tissue viability.

We agree that absolute temperature estimation may be unreliable with the FLIR ONE camera (FLIR Systems, Inc., Wilsonville, Ore.), although the cited study2 bears no relationship to the use of thermography in perforator flap surgery. The relative temperature difference is key to the identification of potential perforators, especially free-style perforator flaps, and we feel the FLIR ONE enhances clinical assessment in this situation. We also agree that more research is required for the validation of such technologies and the optimization of user protocols. We hope that this article will encourage others to integrate thermography into their day-to-day plastic surgery practice and add to the growing body of evidence for the use of this technology.


The authors have no financial interest in any of the products or devices mentioned in this communication.

Joseph T. Hardwicke, Ph.D., F.R.C.S.(Plast.)
Department of Plastic Surgery
University Hospitals of Coventry and Warwickshire
Coventry, United Kingdom
School of Clinical and Experimental Medicine
University of Birmingham
Birmingham, United Kingdom

Joanna M. Skillman, F.R.C.S.(Plast.)
Department of Plastic Surgery
University Hospitals of Coventry and Warwickshire
Coventry, United Kingdom


1. Hardwicke JT, Osmani O, Skillman JM. Detection of perforators using smartphone thermal imaging. Plast Reconstr Surg. 2016;137:3941.
2. Curran A, Klein M, Hepokoski M, Packard C. Improving the accuracy of infrared measurements of skin temperature. Extreme Physiol Med. 2015;4(Suppl 1):A140.


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