Quantification of aortic valve calcification with electron beam tomography - A histomorphometric validation study

Rationale and Objectives: The exact quantification of the amount of calcification in aortic valves may be useful for the identification of risk factors for the progression of aortic valve calcification and to evaluate new therapeutic approaches for aortic valve disease. Electron beam tomography (EBT) allows the in vivo detection of calcifications in coronary vessels and in the aortic valve. The aim of this study was to validate the quantification of aortic valve calcification by EBT with in vivo and in vitro investigations. Methods: In 15 patients (aortic stenosis in 13, aortic regurgitation in 2 cases), EBT was performed before aortic valve replacement (40 cross sections, 3-mm slice thickness, matrix 512 x 512, field of view 28 cm, ECG trigger at 40% of the cardiac cycle). EBT was repeated on the explanted aortic valve using the same protocol. In both data sets, the amount of aortic valve calcification was determined using a volumetric score. In serial cuts of the explanted valve (distance 1 mm), the calcified volume was determined by an independent investigator using histomorphometric analysis. Results: The mean calcified volume of the aortic valves as quantified by EBT was 1650.0 +/- 1401.0 mml in vivo (EBTI) and 1544.4 +/- 1266.5 mml in vitro (EBT2). Histomorphometric analysis showed a mean calcified volume of 1555.7 +/- 1272.5 mml. The mean difference between EBT1 and EBT2 was 4.2 +/- 14.7%, between EBT1 and histomorphometry 3.6 +/- 12. 1%, and between EBT2 and histomorphometry -0.5 +/- 5.9%. Conclusion: EBT allows accurate in vivo quantification of aortic valve calcifications.