2090163 Ultrasound And Optical Backscatter In Crosslinked Rabbit Cornea

s S13 that supports the production of advanced stages of Onchocerca is currently being developed and the feasibility of utilizing highfrequency ultrasound for serial in vivo assessment of parasitic worms was examined. Methods: As a first step towards developing a small animal model for Onchocerciasis, another filarial wormDirofilaria immitis (i.e., canine heartworm) was selected as a model system and injected into NOD.Cg-PrkdcIl2rg/SzJ (NSG) mice. Twelve mice received intraperitoneal or subcutaneous hind leg injections of 100 worms (9 and 3 animals, respectively), while uninfected NSG mice were used as control animals. High frequency (40-50 MHz) ultrasound scanning was performed immediately after injection, 3, and 4 weeks post infection with a Vevo 2100 scanner (Visualsonics, Toronto, Canada). Real-time, grayscale ultrasound assessment of worm size, motility, and echogenicity was performed in vivo (based on in vitro scans of the worms prior to injection). Following completion of the study, the infected mice were euthanized to confirm the presence of worms in the mice and for ex vivo ultrasound scanning. Results: Worms were visualized with ultrasound in 8 out of 9 intraperitoneally injected and in all 3 subcutaneously injected mice. Worms grew up to 3 mm (diameters of 0.1-0.3 mm), with larger worms observed in mice 4 week post injection at depths of 0.35 to 4.3 mm. The same characteristic twisting motion was observed in ex vivo as well as in the in vivo environments, and remained constant throughout the serial ultrasound scans. Ex vivoscanning documented hyperechoic worm echogenicities, while in vivo scanning observed hyper and isoechoic worm echogenicities. Results from the dissected mice supported the ultrasound findings with 10 to 20 % of worms recovered alive. Conclusions: Identification and monitoring of Dirofilaria immitis in mice with high-frequency ultrasound is possible. In vivoworm infections can be visualized immediately after injection as well as up to 4 weeks later. 2090163 Ultrasound And Optical Backscatter In Crosslinked Rabbit Cornea Ronald Silverman, RakshaUrs,Harriet O. Lloyd Ophthalmology, Columbia University Medical Center, New York, NY, United States; Riverside Research, New York, NY, United States Objectives: Photoactivated riboflavin collagen crosslinking (CXL) is becoming a clinically important tool for strengthening the cornea in keratoconus (a disease in which the cornea thins and bulges) and other forms of ectasia (corneal thinning). An important aspect of CXL is to limit crosslinking to the anterior corneal stroma and to avoid damage to the endothelium, a monolayer of cells lining the inner wall of the cornea that maintain corneal transparency through active transport. Our OBJECTIVES: was to utilize high frequency ultrasound (US) and optical coherence tomography (OCT) to evaluate changes in stromal backscatter in a rabbit model of CXL. Methods: After mechanical removal of the epithelium, we performed CXL in 8 eyes of 4 rabbits ex vivo. US and OCT imaging were performed immediately preand postCXL. US scans were performed with an immersion technique using a focused 60 MHz single element transducer. Radiofrequency echo data were acquired at a 400 MHz sample rate. The OCT system (OptoVue, Fremont, CA) is a spectral domain system operating at 830 nm. We performed calibrated spectral analysis to generate midband-fit (MBF) and spectral slope images. Backscatter in OCT images was determined from pixel intensity under standard gain settings. Results:We found increases in anterior stromal backscatter in some, but not all, cases. We also found changes in corneal thickness, with some corneas thickening, others thinning. Backscatter change was correlated with thickness change, with both spectral slope and MBF having R of about 0.25. For OCT, R was 0.55. Spectral slope and MBF change were correlated with OCT backscatter change, with respective R values of 0.72 and 0.39. Conclusions: We believe that in some instances incomplete removal of the epithelium resulted in corneal thinning via dehydration by the dextran solution in which the riboflavin was dissolved. In such cases, the cornea thinned and backscatter tended to decrease. Where epithelial removal was complete, backscatter tended to increase in the anterior stroma. The strong association of increase in spectral slope with increased optical backscatter suggests that CXL-induced changes are at a scale that is small even compared to the approximately 25 micron US wavelength. 2088359 Photoacoustic Imaging Of Vascular Oxygenation Following Dielectric Barrier Discharge Plasma Wound Treatment Natalie Chernets, John R. Eisenbrey, Ji-bin Liu, Qianshi Zhang, Deepa S. Kurpad, TheresaA. Freeman, Flemming Forsberg Radiology, Thomas Jefferson University, Philadelphia, PA, United States; Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States Objectives: While non-thermal dielectric barrier discharge plasma (DBD-plasma) can promote wound healing, the exact mechanism is unclear. Hence, we investigated the in vivo vascular changes associated with DBD-plasma treatment of ear tissue regeneration using photoacoustic (PA) imaging. Methods: Ten, 8 week old C57BL/6 mice received a 2 mm through-and-through hole in the center of the cartilaginous part of each ear as part of an IACUC approved protocol. DBD-plasma treatment (5 s at 1.7 kHz and 17 kV) was performed once daily for the first 5 days on the left ear, while the right ear hole acted as an untreated control. Vascularization, oxygenation and hemoglobin relative to vessel area was measured on days 0 (before and after punch), 4, 11, 16 and 25 using a Vevo LAZR PA scanner (Visualsonics, Toronto, Canada) with a LZ-250 linear array (21MHz center frequency). Photographs of the healing ear holes were taken every 3 days for 32 days and closure of the ear hole was measured by image analysis. After 32 days ear specimens were sent for histology. Results from treated and untreated ears were compared using paired t-tests. Results: At day 0 both control and DBD-plasma treated ears showed significantly elevated blood flow, oxygenation and hemoglobin/vessel area relative to baseline (i.e., prewounding; p,0.001). Vascularity was higher in controls than in DBD-plasma ears on day 4 post-wounding (2260.5% vs 12 60.3%; p50.03) and continued an upward trend for the remaining days, whereas DBD-plasma treatment vascularity leveled off to initial post punch levels at days 16 and 25. Conversely, oxygenation and hemoglobin per vessel area were higher than bilateral controls on day 4 (2460.3 vs 11.560.2; p50.005 and 3.860.6x10 vs 6.161.8x10, p50.1, respectively). After 32 days, control ear holes were 4563.1 % closed, while DBD-plasma treated ears had closed by 8362.7 % (p ,0.001)