Figure 2.

Paradigmatic example of Murray-law based QFR measurement. Murray law-based quantitative flow ratio (μQFR) computation was solely derived from one angiographic projection view; the lumen contour and its side branches were automatically delineated; a step-down reference diameter was calculated based on the Murray bifurcation fractal law. The μQFR values at each position for both the main vessel and its side branches were readily available; A. Pre-procedural angiographic image shows an in-stent restenosis lesion (red arrow) at the proximal left anterior descending artery; the μQFR at the asterisk position was 0.63; B. After drug-coated balloon angioplasty minimal residual stenosis was detected, the the final μQFR was 0.93, as indicated by the asterisk.