Introduction: In reconstructive surgery, there is an increased use of perforator and septo-cutaneous free flaps due to their decreased morbidity of the donor site, better tailoring and remodeling capacity. Determination of perfusion of those flaps is a difficult task that cannot be achieved by usual techniques since few of them are sensitive enough to determine the location of small perforator vessels. For this purpose we used the dynamic infrared imaging (DIRI™) represented by a new non-invasive, non-toxic medical device (BioScanIR®) that allows precise mapping of the superficial temperature and temperature modulation of any tissue. This technology was applied as a pre-operative examination to locate superficial perforators in 17 free flaps.
Methods: 8 DIEP flaps for breast reconstruction, 6 fibular free flaps for mandibular reconstruction, 2 latissimus dorsi flaps and 1 serratus free flap for facial reconstruction were analyzed between May 2004 and March 2005. The day prior to surgery, perforators or septo-cutaneos vessels were located in the donor site by two techniques: flow Doppler and DIRI. An “L” shaped ruler, visible in infrared, was applied over the area of interest to allow precise location of the findings on the infrared image and relate the locations to the patient body, thus allowing comparison of findings with both techniques. The choice of the dominant perforator to be harvested along with the skin paddle was made depending on the vessel diameter found by DIRI.
Results: Perforators and their area of perfusion were found by the DIRI analysis as ‘hot spots' comparing to the surrounding temperature. Analysis was refined by selecting only locations within images corresponding to cardiac systole (frequency analysis using FFT algorithm). Flow Doppler identified the location of the perforators but it does not give information about the area of perfusion. The duration of flow Doppler is approximately 15 minutes as compared with 20 seconds duration of DIRI exam which is more comfortable for patients.
Conclusions: DIRI is a fast and precise non-invasive technique that allows location of superficial perforators and septo-cutaneos vessels. Images found by DIRI analysis can delimitate the area of perfusion of each perforator in contrast to flow Doppler that can demonstrate only their position. This technique permits identification of the main perforator included in the skin paddle increasing the chance of success and reducing the surgical time. This technology can be applied in the surgical planning of free tissue transfers and may be used for post-operative follow up to monitor blood perfusion in the flap.