IMPROVING DETECTION OF CORONARY MORPHOLOGICAL FEATURES FROM DIGITAL ANGIOGRAMS - EFFECT OF STENOSIS-STABILIZED DISPLAY

Background We have developed a digital display method that stabilizes the motion of a stenosis in sequential frames of a coronary angiogram, allowing it to be scrutinized at high display frame rates. The purpos e of this study was to determine whether this technique improves visua l detection of low-contrast luminal morphological features. Methods an d Results An observer detection study was conducted using computer-sim ulated arterial segments containing known target features, inserted in to clinical digital coronary angiograms. Four observers performed a fo rced-choice detection of a simulated filling defect in each of 320 ang iograms using the conventional and stenosis-stabilized dynamic display s (at 7.5, 15, and 32 frames per second) and a single-frame static dis play (total of 8960 detections). In a second simulated clinical task, three observers detected a bridging stenotic lumen in 600 angiograms u sing the two displays (3600 detections). In a third experiment, two an giographers rated the likelihood of intraluminal thrombus in 89 right coronary digital angiograms by consensus reading with both dynamic dis plays. Detectability of the simulated filling defect was similar for b oth dynamic display methods at 7.5 frames per second (averaging twice that for static images). As display rate was increased to 32 frames pe r second, detectability for the conventional display declined, whereas the stabilized display detectability increased for all observers (P<. 05). On average, stabilization allowed detection of filling defects eq uivalent to a 71% increase in feature contrast. Response time for the conventional display averaged 12.9+/-4.7 seconds. For the stenosis-sta bilized display, response time fell with increased frame rate (P<.05) to 4.9+/-1.2 seconds at 32 Hz, similar to the time for static images ( 4.6+/-0.8 seconds). The detectability of the bridging stenotic lumen w as increased by 62% with the stabilization compared with conventional dynamic display (P<.00001). Consensus reading of coronary angiograms s howed differences between the two dynamic display methods (kappa=0.11) that may be explained by an improvement in observer uncertainty. A ra ting of definite for thrombus present or absent was more frequent with the stabilized display (39% versus 15%, P<.0001).Conclusions These da ta suggest that stabilized display of coronary angiograms significantl y increases detectability, reduces the time required for detection, an d improves observer uncertainty for the presence of small luminal morp hological features. The method of angiographic display may thus have a n impact on clinical coronary angiographic interpretation.