Is CT (computed tomography) angio (angiography) appropriate for diagnosing pericarditis?

CT Angiography for Pericarditis

CT angiography (CTA) is not appropriate as a first-line imaging test for pericarditis, and there is no relevant literature supporting its use for this indication. 1

Imaging Hierarchy for Pericarditis

First-Line Imaging: Echocardiography

• Transthoracic echocardiography is the first-line imaging test for suspected pericarditis, providing the most cost-effective way to detect pericardial effusion and assess hemodynamic significance 1, 2
• Echocardiography accurately detects pericardial effusion (one of the four diagnostic criteria for pericarditis), cardiac tamponade, and ventricular dysfunction from myocardial involvement 1
• Note that purely fibrinous acute pericarditis may show a normal echocardiogram, and up to 40% of pericarditis cases may lack typical findings 2

Second-Line Imaging: CT with Contrast (Not CTA)

When CT is indicated, cardiac CT with IV contrast—not CT angiography—should be used as a complementary imaging modality to echocardiography. 1

Specific CT Protocol Considerations:

• CT chest with IV contrast or CT heart function and morphology are the appropriate CT protocols for pericardial disease evaluation 1
• IV contrast administration is recommended to increase blood density and depict pericardial inflammation 1
• Low-radiation cardiac CT using prospective ECG triggering is feasible 1

What CT Can Show:

• Pericardial thickening or enhancement (sensitivity 54-59%, specificity 91-96% for acute pericarditis) 1, 3
• Pericardial calcification (CT is the most accurate technique for this) 1
• Size, location, and density of pericardial effusion not fully demonstrated by echocardiography 1
• Pericardial masses, tumors, and involvement of adjacent structures 1
• CT attenuation values can distinguish exudative from transudative pericardial fluid 1

Why CTA Specifically Is Not Appropriate:

• There is no relevant literature supporting CTA chest or CTA coronary arteries for evaluation of pericardial disease 1
• CTA protocols are designed for vascular imaging (coronary arteries, pulmonary embolism), not pericardial tissue characterization 1
• While CTA may incidentally show pericardial changes like effusion, thickening, or enhancement, it is not a first-line or even second-line test for this purpose 1

Superior Alternative: Cardiac MRI

When echocardiography is nondiagnostic or there is diagnostic uncertainty, cardiac MRI is the preferred advanced imaging modality over CT. 1

• CMR has 94-100% sensitivity for detecting pericardial inflammation 1
• CMR shows pericardial enhancement, thickening, edema on T2-weighted images, and pericardial effusions 1
• CMR can distinguish acute myopericarditis from other cardiomyopathies and occult MI 1
• MRI provides better tissue characterization and functional assessment than CT without radiation exposure 1

Clinical Algorithm

1. Start with transthoracic echocardiography in all patients with suspected pericarditis 1, 2
2. If echocardiography is nondiagnostic or there is diagnostic uncertainty, proceed to cardiac MRI 1
3. Consider cardiac CT with IV contrast (not CTA) only when:
   • MRI is contraindicated or unavailable 1
   • Evaluating for pericardial calcification or thickening in suspected constrictive pericarditis 1
   • Planning pericardiocentesis or pericardiectomy 1
   • Assessing for pericardial masses, tumors, or neoplastic involvement 1

Common Pitfalls

• Do not order CTA protocols (designed for vascular imaging) when evaluating pericardial disease—the appropriate CT study is cardiac CT with IV contrast 1
• CT has limited hemodynamic assessment capability compared to echocardiography and MRI, with suboptimal temporal resolution and increased artifact with tachycardia or unstable rhythm 1
• CT findings for pericarditis have modest sensitivity (54-59%) despite high specificity (91-96%), so negative CT does not exclude pericarditis 1, 3
• Pericardial thickening or enhancement on CT can also represent pericardial fibrosis, not just acute inflammation 1