Thermal, Hyperspectral, and Laser Doppler Imaging: Non-Invasive Tools for Detection of The Deep Inferior Epigastric Artery Perforators—A Prospective Comparison Study

Perforator flaps have become one of the leading procedures in microsurgical tissue transfer. Individual defects require a tailored approach to guarantee the most effective treatment. A thorough understanding of the individual vascular anatomy and the location of prominent perforators is of utmost importance and usually requires invasive angiography or at least acoustic Doppler exploration. In this study, we aimed at evaluating different non-invasive imaging modalities as possible alternatives for perforator location detection. After a cooling phase, we performed thermal, hyperspectral and Laser Doppler imaging and visually evaluated a possible detection of the perforator for a period of five minutes with an image taken every minute. We identified the most prominent perforator of the deep inferior epigastric artery by handheld acoustic Doppler in 18 patients. The detected perforator locations were then correlated. Eighteen participants were assessed with six images each per imaging method. We could show a positive match for 94.44%, 38.89%, and 0% of patients and 92.59%, 25.93%, and 0% of images for the methods respectively compared to the handheld acoustic Doppler. Sex, age, abdominal girth, and BMI showed no correlation with a possible visual detection of the perforator in the images. Therefore, thermal imaging can yield valuable supporting data in the individualized procedure planning. Future larger cohort studies are required to better assess the full potential of modern handheld thermal imaging devices.

Laser Doppler Imaging for Treating Vascular Complications from Procedures Involving Dermal Fillers: Case Series and Literature Review

Vascular occlusion is a rare but severe complication of dermal filler injections. Early treatment of this complication produces better outcomes. Current diagnostic methods for vascular occlusion in the skin are subjective and imprecise; these include capillary refill time, skin color, and reports of pain. This study aimed to assess the use of laser Doppler imaging (LDI) in the evaluation and treatment of vascular complications caused by dermal filler injections. This retrospective study used laser Doppler imaging (LDI) in 13 patients who developed vascular occlusion after facial dermal filler injections, with subsequent follow-up. The precise areas of perfusion observed on LDI were compared with the findings of clinical and photographic evaluation. The results showed that LDI accurately identified areas of vascular occlusion and improved treatment precision among these thirteen patients. The procedure was more precise than visual inspection or photographic evidence. Satisfactory outcomes were achieved for all patients, and no procedure-related complications were reported. Collectively, LDI provides fast, noninvasive, and accurate delineation of areas of vascular occlusion caused by complications of dermal filler injections and avoids several subjective shortcomings of visual and photographic evaluations. Thus, LDI effectively tracks treatment outcomes. However, large-scale studies are required to confirm the present findings.

32 Does the Use of Silicone Gel Sheeting Impact the Overall Physiology of Hypertrophic Scar Development? A Feasibility Trial Using Laser Doppler Imaging to Assess Perfusion in Native Skin and Immature Burn Scar

Introduction The use of silicone gel sheeting (SGS) has long been observed clinically as an effective modality in reducing hypertrophic scar (HTS) formation. Although the use of SGS is widely accepted, the exact mechanism is not fully understood. Prevailing theory suggests silicone suppresses collagen production in immature active scar. Collagen production is enhanced as blood flow increases in areas of scar hyperemia. Reduction of blood perfusion to the immature scar may act as a potential mechanism in limiting excessive scar proliferation. Methods Laser Doppler Imaging (LDI) was used to assess 2 areas in 2 subjects (85% TBSA w/ CEA and native skin control): A control site and SGS testing site were traced on the skin of each subject and 5 LDI scans were performed on both subjects: 1) initial without SGS; 2) initial with SGS applied; 3) 4-hours post-SGS application with SGS on; 4) 4-hours post-SGS application immediately after removal; 5) 15-minutes post-SGS removal. The control and testing site for both subjects were then analyzed using the LDI software and the average perfusion units (PU) over the region of interest (ROI1: testing site; ROI2: control site) areas were calculated for each scan. Results Perfusion within both ROI had a marked increase in perfusion for HTS scans after 4-hours when compared to the initial scan. However, after initial SGS application to ROI1, the mean PU decreased by 23.1% while the perfusion to ROI2 remained relatively constant (-5.8%). Subsequently, the ROI2 increased in mean PU by 23.4% 4-hours after the initial scan while the ROI1 showed a blunted response in perfusion in comparison increasing by only 2.3%. Conclusions Perfusion for both NS and HTS were notably decreased when SGS was applied compared to the matched ROI without SGS. In addition, prolonged SGS application created a greater difference in perfusion between silicone (less perfusion) and non-silicone sites (greater perfusion) for both NS and HTS when compared to initial SGS application demonstrating a greater effect on perfusion the longer SGS was worn.

Laser Doppler imaging evaluation of nitroglycerin patch application in systemic sclerosis patients

Recent studies suggest the use of topical nitroglycerin (NTG) application in systemic sclerosis (SSc)-associated Raynaud phenomenon (RP). With the current study, we aimed to characterize for the first time the microvascular response to a NTG patch (Trinipatch® 5 mg/24 h) applied to the hand dorsum in patients with SSc using Laser Doppler imaging (LDI) at baseline and following a cold challenge. The study included 21 patients with SSc and 13 controls. Blood flow was evaluated by LDI at the level of the fingertips and metacarpus. Microvascular morphology was evaluated by nailfold capillaroscopy (NC). LDI revealed decreased fingertip baseline perfusion and a stronger vasoconstrictor response to a cold challenge in patients with SSc versus control. Metacarpal application of a NTG patch led to an increase in blood flow and hand temperature in patients with SSc. Furthermore, NTG administration led to a faster reperfusion after cold challenge. Correlation analyses revealed that the magnitude of the vasodilatory response was inversely related to baseline fingertip perfusion and hand temperature, but unrelated to the number of capillaries/mm assessed using NC. In conclusion, we provide evidence of a vasodilatory reaction following NTG patch application in patients with SSc using LDI and a protective effect against cold challenge. The magnitude of the response to NTG was related to functional, but not structural features. Our results support a further evaluation of the NTG patch as a possible therapeutic agent in SSc-associated RP.