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Fractional CO2 laser ablation of porcine burn scars after grafting: Is deeper better?
摘要： Introduction: Fractional CO2 lasers have been used in clinical settings to improve scarring following burn injury. Though used with increasing frequency, the appropriate laser settings are not well defined and overall efficacy of this therapy has not been definitively established. As it has been proposed that for thick hypertrophic scars proportionally greater fluence and thus deeper ablation into the scar tissue would be most effective, the goal of this study was to examine the role of ablation depth on scar outcomes in a highly-controlled porcine model for burn scars-after grafting. Methods: Properties of laser ablated wells were quantified on ex vivo pig skin as a function of laser energy (20, 70 or 150mJ). Full-thickness burn wounds were created on the dorsum of red Duroc pigs with the eschar excised and grafted with a split-thickness autograft meshed and expanded 1.5:1. After four weeks of healing, sites were treated with either 20, 70, or 150 mJ pulse energy from a fractional CO2 laser at 5% density or left untreated as a control. Sites were treated every four weeks with three total sessions. Scar area, pigmentation, erythema, roughness, histology, and biomechanics were evaluated prior to each laser treatment at day 28, 56, and 83, as well as four weeks after the final laser treatment, day 112. Additional biopsies were collected at day 112 for gene expression analysis. Results: The depth of the laser ablated wells increased with increasing pulse energy while the width of the wells was smaller in the 20mJ group and not significantly different in the 70 and 150mJ groups. Scar properties (area, color, biomechanics) were not significantly altered by laser therapy at any of the laser energies tested versus controls. Average scar roughness was improved by laser therapy in a dose dependent manner with scars treated with 150mJ of energy having the smoothest surface; however, these changes were not statistically significant. Assessment of matrix metalloproteinase 9 gene expression showed a slight upregulation in scars treated with 70 or 150 mJ versus control scars and scars treated with 20mJ pulse energy. Conclusion: The current study demonstrated that the properties of the ablative well (depth and width) are not linearly correlated with laser pulse energy, with only a small increase in well depth at energies between 70 and 150 mJ. Overall, the study suggests that there is little difference in outcomes as a function of laser energy. Fractional CO2 laser therapy did not result in any statistically significant benefit to scar properties assessed by quantitative, objective measures, thus highlighting the need for additional clinical investigation of laser therapy efficacy with non-treated controls and objective measures of outcome.
关键词： Power,Fractional CO2 laser,Porcine model,Quantitative assessment,Burn scars
更新于2025-09-11 14:15:04
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Improving visualization and quantitative assessment of choriocapillaris with swept source OCTA through registration and averaging applicable to clinical systems
摘要： Choriocapillaris (CC) visualization and quantification remains challenging. We propose an innovative three-step registration and averaging approach using repeated swept source optical coherence tomography angiography (SS-OCTA) scans to conduct automatic quantitative assessment on CC. Six subjects were enrolled, each imaged at several locations with SS-OCTA from macular to equatorial regions using 3 mm × 3 mm scanning pattern. Five repeated volumes were collected for each subject. The complex optical microangiography (OMAG) algorithm was applied to identify blood flow in CC slab. An automatic three-step registration of translation, affine and B-Spline was applied to en face OCTA images of CC, followed with averaging. A fuzzy clustering approach was used to segment vasculature and flow deficits from the averaged images. The improvement in visualization of CC was evaluated and the average intercapillary distance was estimated by calculating the averaged capillary lumen spacing. A series of quantitative indices of flow deficit density, number, size, complexity index and aspect ratio index (FDD, FDN, FDS, FDCI and FDARI) were designed and validated with the increase of repeated scan numbers for averaging. Quantitative assessment was applied and compared on CC in macular and equatorial regions. The intercapillary distance was observed to be around 24 μm at macula and increased toward equatorial regions. All five quantitative indices (FDD, FDN, FDS, FDCI and FDARI) showed significant changes with multiple averaging and tend to become stable with repeated number of 4. Our proposed registration and averaging algorithm significantly improved the visualization of CC with SS-OCTA. The designed five indices for CC provide more options in the quantitative assessment of CC and are of great potentials in assisting the understanding of disease pathology, early diagnosis and treatment monitoring.
关键词： quantitative assessment,optical coherence tomography angiography,choriocapillaris,averaging,registration
更新于2025-09-10 09:29:36
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Quantitative Assessment of the Blood Perfusion of the Gastric Conduit by Indocyanine Green Imaging
摘要： Background: Indocyanine green (ICG) ?uorescence imaging has been used to assess the blood perfusion of the gastrointestinal tract in surgery. Especially, it was used to determine the best anastomotic site. However, in previous studies, ICG ?uorescence was judged subjectively based on the visual appearance. This study evaluated the usefulness of our novel method to quantitatively assess the blood perfusion of the gastric conduit in esophagectomy based on ICG ?uorescence. Materials and methods: Twenty patients who underwent esophagectomy with gastric conduit reconstruction were prospectively investigated. Using a camera in contact with the surface of the stomach, ICG images were quantitatively evaluated using “ROIs”, a software program that quanti?ed the ?uorescence intensity and created a time-?uorescence intensity curve to assess the blood perfusion three times intraoperatively. Results: No postoperative esophago-gastrostomy leakage developed. However, after preparing the gastric conduit and just before anastomosis, the maximum increase in ?uorescence intensity (FImax) signi?cantly decreased (48.8 (cid:1) 26.0 and 31.5 (cid:1) 14.9 versus 84.9 (cid:1) 28.2; P < 0.001 and P < 0.001, respectively), and the time to reach FImax was signi?cantly extended (60 (cid:1) 35.4 and 58.3 (cid:1) 34.9 versus 18.9 (cid:1) 6.5; P < 0.001 and P < 0.002, respectively), in comparison to the control value. Just before anastomosis, 18 cases (90%) showed an identical pattern characterized by an obtuse and low arterial in?ow peak and a slow rise of ?uorescence intensity over time, indicating a decreased blood ?ow. Conclusions: The quantitative analysis of ICG ?uorescence imaging could objectively prove a decrease in blood perfusiondwhich could not be determined macroscopicallydin the gastric conduit before esophageal reconstruction. The results from the present and further studies may indicate its clinical value.
关键词： Gastric conduit,Anastomotic leakage,Indocyanine green,Esophagectomy,Blood perfusion,Quantitative assessment
更新于2025-09-04 15:30:14
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Functional Capillary Density for in Vivo Estimation of Intestinal Perfusion using Real-Time Confocal Endomicroscopy
摘要： Background and aim: Confocal Laser Endomicroscopy (CLE) has been successfully used to appreciate microcirculation changes of the digestive mucosa. Our aim was to evaluate CLE scanning complemented by functional capillary density area (FCD-A) estimation to define the micro-vessel status in a reiterate, long-lasting porcine model of bowel ischemia. Materials and methods: A laparotomy was performed in 4 pigs, and a segmental (3–4 cm) ischemia of the sigmoid colon was induced with vascular clamps. Ischemic and perfused regions were clinically defined. After an injection of 5 ml of sodium fluorescein 10% (Fluocyne, SERB, Paris, France), the Cellvizio? confocal probe (Mauna Kea Technologies, Paris, France) was directly applied onto the mucosa’s surface through a full-thickness enterotomy. Both ischemic area (IA) and control region-perfused area (PA) – were scanned and video sequences were recorded. Results: Confocal evaluation of the ischemic area revealed a different aspect of the mucosal tissue when compared to the normal perfused area. Statistically, FCD-A at the perfused area was significantly higher when compared to the ischemic area, irrespective of the time point. After 1 hour, FCD-A was (0.189 ± 0.094 vs. 0.365 ± 0.030; p=0.0001), after 2 hours (0.252 ± 0.056 vs. 0.389 ± 0.024; p<0.0001), after 3 hours (0.252 ± 0.050 vs. 0.353 ± 0.030; p=0.0001) and after 4 hours (0.262 ± 0.044 vs. 0.358 ± 0.019; p<0.0001), at ischemic and perfused areas respectively. Conclusions: Confocal imaging allows real-time discrimination between perfused and ischemic areas of the bowel using morphological clues, while the functional capillary density area adds a quantitative measurement.
关键词： Cellvizio? system,Quantitative assessment of bowel perfusion,Functional capillary density area,Confocal laser endomicroscopy
更新于2025-09-04 15:30:14