HIV induced pericarditis CT scan
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ramyar Ghandriz MD[2]
Overview
CT is a very effective diagnostic tool in cases of pericardial effusion due to any reason as it helps us to narrow down on the etiology by determining the amount and nature of the pericardial fluid. CT is very useful especially in identifying hemorrhagic effusions or clots within the pericardium. A pericardial effusion is often incidentally noted on CT scans obtained for other indications.
CT Scan
If the fluid is free-flowing and not loculated, it will first accumulate at the posterior lateral aspect of the left ventricle in the supine position. It can be hard to differentiate a small pericardial effusion from pericardial thickening of about 4 mm since both entities generate a similar signal. In the presence of acute pericarditis, the pericardium can generate an intermediate signal intensity and may enhance after gadolinium administration.
Estimation of the amount of fluid is possible to a limited extent based on the overall thickness of the crescent of fluid. Hemorrhagic effusions can be differentiated from a transudate or an exudate based on signal characteristics (high signal on T1-weighted images) or density (high-density clot on CT). Pulsation artifacts may cause local areas of low signal in a hemorrhagic effusion.
- CT attenuation measurements also enable the initial characterization of pericardial fluid.
- A fluid collection with attenuation close to that of water is likely to be a simple effusion.
- Attenuation greater than that of water suggests malignancy, hemopericardium, purulent exudate, or effusion associated with hypothyroidism.
- Pericardial effusions with low attenuation also have been reported in cases of chylopericardium.
Advantages of Computed Tomography over Echocardiography in the Assessment of Pericardial Effusion
Both MRI and CT have an advantage over echocardiography insofar as they can detect loculated effusions as well as generalized effusions[1] [2]. Computed tomography superior to MRI in the assessment of pericardial calcification.