IN-VIVO ACCURACY OF 2 RADIOGRAPHIC SYSTEMS IN THE DETECTION OF BJORK-SHILEY CONVEXO-CONCAVE HEART-VALVE OUTLET STRUT SINGLE LEG SEPARATIONS

Objective: Modified cineradiographic systems have been used clinically to detect partially broken outlet struts in normally functioning Bjor k-Shiley convexo-concave heart valves, Almost all such valves were exp lanted, presuming that full failure would likely follow Inasmuch as th e clinical setting only rarely permits examination of normally rated v alves, the accuracy of radiographic detection cannot be clinically def ined, This study uses the clinical radiographic technique in sheep imp lanted with known status convexo-concave valves, comparing its accurac y and that of a newly developed, geometric image magnification radiogr aphy system, Methods: Twenty-one sheep with mitral convexo-concave val ves were studied on both systems, Five were used for extensive trainin g, When operators were expert with both systems, images of four intact valves and 12 valves with outlet strut single leg separations, along with a seventeenth single leg separation valve used for calibration, w ere integrated into 112 image sets organized into a balanced incomplet e block design for evaluation by eight trained, blinded reviewers, Res ults: Cineradiography sensitivity vas 24% versus 31% for direct image magnification, The odds ratio for detection of single leg separation b y direct image magnification versus cineradiography was 2.0 (95% confi dence interval, 0.76 to 5.9; p = 0.13), Cineradiography specificity wa s 93% versus 90% for direct image magnification, Sensitivity and speci ficity varied markedly by reviewer, with sensitivity ranging from 8% t o 55% and specificity from 51% to 100% for the combined technologies, Conclusions: The data support the need for more intensive training for convexo-concave valve imaging and further investigation of unconventi onal radiographic technologies, Clinical cineradiography of convexo-co ncave valves may detect as little as 25% of valves having a single leg separation, underestimating the prevalence of single leg separations and thereby implying more rapid progression to full fracture than is a ctually the case.