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 dimension measurements of a newly developed method of quantitative angioscopy.

METHODS

A method was developed for quantitation of luminal dimensions during angioscopy, as variation in magnification with lens-object distance and ambiguity associated with identification of corresponding points about the circumference of a given discrete cross-section render subjective estimates unreliable. A transverse ring of fiberoptically transmitted light was emitted from a guidewire or its housing at a known distance from the distal end of an angioscope and discrete cross-sections of interest were observed as the ring of light was reflected from the luminal surface. Caliper measurement of the diameter of the light ring image (< 50 mW at 488/515 nm), obtained on angioscopic video recordings of cylindrical phantom vessels of known dimensions, was performed by three observers on five occasions.

RESULTS

The mean absolute difference between measured and known luminal diameter (n = 405 observations) was 65 microns +/- 35 microns and the mean coefficient of variation was 4.2%, and the mean difference between measured and known areas (n = 195 observations) was 0.4 mm2, with a mean coefficient of variation of 6.5%.

CONCLUSION

By use of this new lightwire method, luminal dimensions can now be measured in vitro with a high degree of accuracy and reproducibility during angioscopy.