The detectability of posterior portion of superior pericardial recess on routine chest CT

The aim of this study was to search for the conspicuity, shape and size of posterior portion of superior pericardial recess (SPR) on routine spiral chest computed tomography (CT). Chest CTs of 180 consecutive patients were reviewed for the presence of the posterior portion of SPR, retrospectively. All images were reevaluated on a workstation by two radiologists in consensus with a constant window setting (window level 50 HU, window width 350 HU). Uniform, sharply outlined structure of near water density, without walls and rims in the posterior aspect of the ascending aorta was defined as posterior portion of the SPR. Identifiable recesses were classified as linear, crescentic, semicircle and amorphous in appearance. The depth of the recess was measured. Pericardial thickness, diameters of ascending and descending aorta, and pulmonary artery and its major branches were noted. Statistical analyses were performed to scrutinize any relationship between the presence of the recess, its shape, depth, gender, pericardial thickness and diameters of thorasic vessels. The recess was identified in 174 (96%) patients. Seventy-nine (45%) recesses were semicircular, 47 (27%) linear, 39 (23%) amorphous and 9 (5%) crescentic. The mean depth was 6 +/- 3.5 mm. The mean diameter of ascending, descending aorta, and pulmonary artery and its main branches were 33.6 +/- 5 mm, 25.7 +/- 3.7 mm, 23.2 +/- 2.6 mm, 19.2 +/- 2.6 mm, and 19.3 +/- 2.6 mm, respectively. The mean pericardial thickness was 2.7 +/- 0.6 mm. The shape and depth of the recess did not correlate with age, gender, vascular diameters and pericardial thickness. The posterior portion of SPR may be encountered in the majority of patients. Conspicuity of the recess may be due to individual variability.