IN-VIVO COMPARISON OF SCANNING TECHNIQUE AND WAVELENGTH IN LASER-DOPPLER PERFUSION IMAGING - MEASUREMENT IN KNEE LIGAMENTS OF ADULT-RABBITS

At present, there are only two laser Doppler perfusion imaging systems (LDIs) manufactured for medical applications:a 'stepwise' and a 'cont inuous' scanning LDI. The stepwise scanning LDI has previously been in vestigated and compared with coloured microsphere determined standardi sed flow. The continuous scanning LDI is investigated and compared wit h the stepwise scanning LDI for its ability to measure in vivo, hypoae mic, ligament tissue blood flow changes. The continuous scanning syste m was supplied with two lasers, red and near infrared (NIR), allowing for additional assessment of the effect of wavelength on imaging ligam ent perfusion. Perfusion images were obtained from surgically exposed rabbit medial collateral ligaments (MCL). Continuous and stepwise LDI scans were compared using correlation and linear regression analysis o f image averages and standard deviations. Using the same method of ana lysis, LDI measurements using red and NIR lasers indicated a high degr ee of correlation, at least over the ranges of perfusion assessed, ind icating that red and NIR lasers measure similar regions of flow in the rabbit MCL. These experiments confirm that both LDI techniques provid e a valid in vivo measure of dynamic changes in connective tissue perf usion and could have significant impact on the understanding and treat ment of joint injury and arthritis.