Can a Non-Contrast Chest CT Show Pericarditis?
A non-contrast chest CT has limited diagnostic utility for pericarditis, with scant evidence supporting its use, though it may detect pericardial thickening and effusion—however, it cannot demonstrate pericardial inflammation, which requires intravenous contrast administration. 1
Limitations of Non-Contrast CT for Pericarditis
The European Society of Cardiology explicitly recommends intravenous administration of iodinated contrast material to depict pericardial inflammation, which is a key diagnostic feature of acute pericarditis. 1 Without contrast, CT cannot demonstrate the pericardial enhancement that characterizes active inflammation.
The American College of Radiology states there is scant evidence to support the use of CT chest without IV contrast for evaluating suspected pericardial disease. 1 While non-contrast CT can identify some anatomical abnormalities, it misses the critical inflammatory component.
What Non-Contrast CT Can Show
Non-contrast chest CT may detect:
- Pericardial thickening (normal pericardium measures 0.7-2.0 mm; thickening >2-3 mm may suggest disease) 1, 2
- Pericardial effusion (fluid accumulation in the pericardial space) 1, 2
- Pericardial calcification (CT is the most accurate technique for imaging calcified tissue, particularly relevant in constrictive pericarditis) 1
- Bilateral pleural effusions (associated with increased risk of cardiac tamponade, OR = 7.52) 1
However, pericardial thickening alone has modest sensitivity (54-59%) for diagnosing acute pericarditis, even when present, and cannot distinguish between acute inflammation, chronic fibrosis, or other causes of thickening. 3, 4
Diagnostic Performance and Clinical Context
Research demonstrates that pericardial thickening/enhancement is the most accurate CT parameter for pericarditis, but requires contrast administration to achieve specificity of 91-96%. 3 Without contrast, the specificity drops substantially because thickening alone can represent fibrosis rather than acute inflammation. 4
The European Society of Cardiology guidelines emphasize that CT findings in acute pericarditis include thickened pericardial layers enhancing after contrast administration—the enhancement component is explicitly listed as a key diagnostic feature. 1
Recommended Imaging Algorithm
Start with transthoracic echocardiography, which the European Society of Cardiology identifies as the most cost-effective first-line imaging modality for suspected pericarditis, detecting effusion and assessing hemodynamic significance. 1, 4
If echocardiography is nondiagnostic or there is diagnostic uncertainty:
- Cardiac MRI is the preferred advanced imaging modality, with 94-100% sensitivity for detecting pericardial inflammation and superior tissue characterization capabilities. 4, 5
- Cardiac CT with IV contrast (not non-contrast) should be considered only when MRI is contraindicated or unavailable, or when evaluating for pericardial calcification in suspected constrictive pericarditis. 4, 1
Common Pitfalls
Do not order non-contrast chest CT specifically to diagnose pericarditis—it lacks the sensitivity and specificity needed for this indication. 1 If CT is clinically indicated for other reasons (e.g., pulmonary embolism evaluation) and incidentally shows pericardial thickening or effusion, this may raise suspicion for pericarditis, but definitive diagnosis requires either contrast-enhanced CT or preferably cardiac MRI. 3, 4
Negative non-contrast CT findings do not exclude pericarditis, as the study cannot assess for pericardial inflammation without contrast enhancement. 4 Many patients with acute pericarditis may have normal or near-normal appearing pericardium on non-contrast imaging. 1
The American College of Radiology notes that CT has limited hemodynamic assessment capability compared to echocardiography, with suboptimal temporal resolution and increased artifact with tachycardia or unstable rhythm. 1