Magnetic resonance imaging of the superior pericardial recesses.

The potential of magnetic resonance imaging (MRI) of the superior pericardial space was evaluated in a retrospective review of MR images of 46 subjects. The superior pericardial space and its two recesses had low signal intensity. The preaortic recess was demonstrated on 82% of nongated transverse scans. The retroaortic recess was demonstrated on 67% of nongated transverse scans. Generally, both recesses were shown with an even higher frequency on ECG-gated and ECG-permutation-gated scans. Knowledge of the location and typical appearance of these pericardial recesses should preclude mistaking them on MRI for a vascular structure, aortic dissection, or an atherosclerotic plaque or mural thrombus within the ascending aorta.