Quantitative validation of cineangiographic biplane axial oblique right ventricular volume measurement

Abstract

Axial cranial oblique biplane views of the right ventricle (RV) permit unique assessment of the RV outflow tract, relationship of the great vessels, and anatomy of the proximal pulmonary arteries. This view may also be useful in assessment of RV free wall and RV septal wall motion. However, the accuracy of volumes derived from biplane angiocardiography with the use of the axial cranial oblique projection has not been adequately validated or compared to conventional views. Nineteen RV animal casts whose volume was determined by water displacement were filmed in conventional posteroanterior/lateral (PA/Lat), 30-degree right anterior oblique/60-degree left anterior oblique ( 30°RAO 60°LAO ) views and in angulated 35-degree right anterior oblique/55-degree left anterior oblique/30-degree cranial (35°RAO/55°LAO/30°Cr) view. Tracings of biplane cast images were analyzed for RV volume by Simpson's rule. RV cast volume was significantly overestimated by 12.2 ± 6.8, 6.0 ± 5.3, and 9.3 ± 9.5 ml in PA/Lat, 30°RAO 60°LAO , and 35°RAO/55°LAO/30°Cr views, respectively. The correlation coefficient ( r) and the standard error of the estimate (SEE) for true vs calculated volume was 0.96, 0.98, and 0.97, and 6.8, 5.2, and 7.3 ml, respectively, for PA/Lat, 30°RAO 60°LAO , and 35°RAO/55°LAO/30°Cr views. Although there was a high correlation of angiographic volumes with true volume in all three views, the 30°RAO 60°LAO projection had the most ideal regression characteristics with highest r value and the lowest SEE. Although, the 30°RAO 60°LAO view most accurately represents RV volume, the 35°RAO/55°LAO/30°Cr view permits unique RV anatomic assessment with an acceptable measure of RV volume.