QUANTITATIVE ANGIOSCOPY - A NOVEL METHOD OF MEASUREMENT OF LUMINAL DIMENSIONS DURING ANGIOSCOPY WITH THE USE OF A LIGHTWIRE

Purpose: To determine the accuracy and reproducibility of luminal dime nsion measurements of a newly developed method of quantitative angiosc opy. Methods: A method was developed for quantitation of luminal dimen sions during angioscopy, as variation in magnification with lens-objec t distance and ambiguity associated with identification of correspondi ng points about the circumference of a given discrete cross-section re nder subjective estimates unreliable. A transverse ring of fiberoptica lly transmitted light was emitted from a guidewire or its housing at a known distance from the distal end of an angioscope and discrete cros s-sections of interest were observed as the ring of light was reflecte d from the luminal surface. Caliper measurement of the diameter of the light ring image (< 50 mW at 488/515 nm), obtained on angioscopic vid eo recordings of cylindrical phantom vessels of known dimensions, was performed by three observers on five occasions. Results: The mean abso lute difference between measured and known luminal diameter (n = 405 o bservations) was 65 mum +/- 35 mum and the mean coefficient of variati on was 4.2%, and the mean difference between measured and known areas (n = 195 observations) was 0.4 mm2, with a mean coefficient of variati on of 6.5%. Conclusion: By use of this new lightwire method, luminal d imensions can now be measured in vitro with a high degree of accuracy and reproducibility during an angioscopy.