Maximal thickness of the normal human pericardium assessed by electron-beam computed tomography

The purpose of this study was to determine the maximal value of normal peri cardial thickness with an electron-beam computed tomography unit allowing f ast scan times of 100 ms to reduce cardiac motion artifacts. Electron-beam computed tomography was performed in 260 patients with hypercholesterolemia and/or hypertension, as these pathologies have no effect on pericardial th ickness. The pixel size was 0.5 mm. Measurements could be performed in fron t of the right ventricle, the right atrioventricular groove, the right atri um, the left ventricle, and the interventricular groove. Maximal thickness of normal pericardium was defined at the 95th percentile. Inter-observer an d intra-observer reproducibility studies were assessed from additional CT s cans by the Bland and Altman met hod [24]. The maximal thickness of the nor mal pericardium was 2 mm for 95 % cases. For the reproducibility studies, t here was no significant relationship between the inter-observer and intra-o bserver measurements, but all pericardial thickness measurements were less than or equal to 1.6 mm. Using electron-beam computed tomography, which ass ists in decreasing substantially cardiac motion artifacts, the threshold of detection of thickened pericardium is statistically established as being 2 mm for 95 % of the patients with hypercholesterolemia and/or hypertension. However, the spatial resolution available prevents a reproducible measure of the real thickness of thin pericardium.