Left pulmonic recess of the pericardium: findings at CT and MR imaging.

PURPOSE: To assess the prevalence and appearance of fluid in the left pulmonic pericardial recess (LPR) on computed tomographic (CT) scans and magnetic resonance (MR) images of patients without pericardial effusion.
MATERIALS AND METHODS: Eighty consecutive contrast material-enhanced CT scans and 50 consecutive MR images of the thorax were evaluated for the presence of fluid in the LPR, transverse sinus, and superior pericardial recess.
RESULTS: Fluid was identified in the LPR in approximately 25% of patients without pericardial effusion (14 of 62 CT scans, eight of 30 MR images). At MR imaging, the LPR and other recesses appeared as a signal void on spin-echo images but demonstrated high signal intensity on gradient-echo flow-sensitive images.
CONCLUSION: Recognition that fluid in the LPR can be a normal finding in patients without pericardial effusion should help avert misdiagnoses of lymphadenopathy.