Posterior choroidal boundary morphology and segmentation errors influence on choroidal thickness assessment in diabetic patients - a swept-source OCT study.

Objective: to evaluate the choroidal morphology and choroidal thickness (CT) in normal and diabetic subjects and to compare the differences between automated segmentation (AS) and manual segmentation (MS) of the choroid. Methods: in this observational cross-sectional study we included 48 eyes: 24 normal eyes (group 1), 9 eyes with DM without diabetic retinopathy (DR) (group 2) and 15 eyes with DM and DR (group 3). Swept-source OCT line scans images were analyzed for the presence of the suprachoroidal layer (SCL), choroidal morphology and the CT was measured manually subfoveal and at 750 µ both nasal and temporal to the fovea after AS and MS. SCL was not included in the CT evaluation. CT values were compared between the groups and between the three points of evaluation. Results: SCL was visualized in 21 eyes (43.8%). In diabetic patients, SCL was visible in 11 (45.83%) cases and in nondiabetic patients, in 10 eyes (41.66%). There was a good AS of Bruch's membrane, which was not further corrected manually. There were statistically significant differences between AS and MS at the level of CSJ for all three locations in all three groups (P ≤ 0.01). After MS, the choroid was statistically significantly thicker. Group 2 and group 3 showed a higher CT thickness. There were no statistically significant differences in the CT between groups in all three locations. Conclusions: Defining posterior choroidal boundary and the applied segmentation method can result in differences in CT measurements. Diabetic patients have altered CT and choroidal morphology. Abbreviations: CT = choroidal thickness, AS = automated segmentation, MS = manual segmentation, CSJ = choroidoscleral junction, SCL = suprachoroidal layer, SCS = suprachoroidal space, DM = diabetes mellitus, DR = diabetic retinopathy, RPE = retinal pigmented epithelium, BM = Buch's membrane.

Role of Ultrahigh Frequency Ultrasound in Evaluating Experimental Flaps.

BACKGROUND: Experimental flap follow-up needs faster, safer, and less invasive techniques that can be easily correlated to clinical procedures. For this reason, we aimed to test the role of ultrahigh frequency ultrasound in follow-up of flap viability. Further on, we aimed to analyze if the chimeric groin flap can be mobilized in a sandwiched position without affecting its vascular supply by twisting its pedicle. METHODS: A total of 12 male Wistar rats, split into three groups, were used. Group A (n = 4) had the chimeric groin flap repositioned in a sandwich position on the anterior abdominal wall and underwent ultrahigh frequency ultrasound follow-up at days 10 and 14. Group B (n = 4) also had the flaps sandwiched, however, at day 14 the vascularity of flaps was proven by infusion of nontargeted ultrasound contrast agents, after which flaps were sent for histological analysis. Group C (C1 n = 2, C2 n = 2) was the control group. In C1 the chimeric groin flap was harvested and sent for histology on day 0, acting as a histological benchmark of flap viability, and in C2 the chimeric groin flap was re-sutured in its anatomical position and after 14 days, flaps were harvested and sent for histological analysis, acting as a direct control for Group B. RESULTS: Ultrasound showed constant vascular flow in both adipose and skin flaps in the sandwiched position. Microbubble study showed diffuse perfusion within flaps. Ultrasound measurements of flow velocity, flap volume, and percentage of vascularity showed a decrease in flap volume and increase in vascularity over 14 days. Histology showed similar viability in both groups. CONCLUSION: Ultrahigh frequency ultrasound may be a valuable tool for postoperative flap assessment, while the chimeric flap can be moved freely in a sandwich position making it suitable for adding tissue substitutes within its components.

New Chimeric Groin Flap: Experimental Model in Rats.

AIM: Increased emphasis is on using tissue substitutes and stem cells to improve flap applicability and survival rates. To accomplish this, the first step is to have a versatile experimental flap, easy to harvest and use as a template. We sought to develop a reliable experimental chimeric groin flap with free mobility and reliable bloods supply that can be twisted, relocated, and integrated easily with other materials. MATERIALS AND METHODS: Ten male Wistar rats were included. The flap consists of a 2.5-cm skin paddle centered on the medial branch of the inferior epigastric artery and a 4.5/2-cm fat pad supplied by the lateral branch of the inferior epigastric artery. After being raised, flaps were resutured in their anatomical position. Flaps were followed up for 15 days. At the end of the study, the viability of flaps was analyzed by ultrahigh-frequency ultrasound, nontargeted contrast study, and histology assessment. RESULTS: All flaps survived without significant complications. Nontargeted microbubbles spread evenly in both the superficial and deep flap. Ultrasound assessment at day 15 showed no significant areas of necrosis or edema. Histology examination of 3 random flaps confirmed vessel patency and flap viability. CONCLUSION: We propose a simple, easy to harvest and reliable experimental flap which offers a main advantage of all-around mobility through its chimeric design. It is a suitable model for bioengineering studies as it can be used as a template for integration of tissue substitutes or stem cells, between its 2 components.