Comparing thin-section and thick-section CT of pericardial sinuses and recesses.

OBJECTIVE: The aim of this study was to assess the prevalence and appearance of the pericardial sinuses and recesses on thin-section (2.5- or 3-mm) CT scans compared with thick-section (5- or 7-mm) CT scans.
MATERIALS AND METHODS: Nine hundred forty-one consecutive contrast-enhanced chest CT scans were retrospectively evaluated. Three hundred sixty-five patients underwent thin-section CT, and 576 patients underwent thick-section CT. The prevalence and appearance of every pericardial recess were determined.
RESULTS: Large recesses such as the superior aortic recess were depicted in 12.5-30.4% of patients using thick-section CT, whereas smaller recesses such as the postcaval recess were depicted in fewer than 5% of patients. With thin-section CT, the depiction rates increased significantly compared with thick-section CT (p < 0.01). Large recesses were depicted in 28.7-44.7% of patients, and smaller recesses were recognized in 10.8-19.8% of patients. Generally, most recesses were linear if they were small and became band-shaped as the fluid increased. However, the recesses were often visualized as crescent, triangle, spindle, ovoid, hemisphere, or irregular shapes.
CONCLUSION: Pericardial sinuses and recesses are more frequently and better depicted on thin-section CT scans. Knowledge of their locations and shapes is helpful for distinguishing pericardial fluid from abnormal findings such as lymphadenopathy and cystic lesions.