What conditions can a chest CT (computed tomography) angiogram diagnose?

What a Chest CT Angiogram Can Diagnose

Chest CT angiography is a comprehensive imaging modality that can diagnose pulmonary embolism, aortic dissection and aneurysm, coronary artery disease (when ECG-gated), pulmonary hypertension, vascular tumors, and inflammatory vascular conditions in a single examination.

Primary Vascular Pathologies

Pulmonary Embolism

• CT pulmonary angiography (CTPA) is the primary imaging modality for evaluating suspected pulmonary embolism, demonstrating both acute and chronic thromboembolic disease 1, 2.
• Acute PE manifests as partial or complete intraluminal filling defects with sharp interfaces against contrast material, with affected arteries often enlarged in complete occlusion 3.
• Chronic PE shows complete occlusive disease in vessels smaller than adjacent patent vessels, evidence of recanalization, webs or flaps, and partial filling defects forming obtuse angles with vessel walls 3.
• CTPA provides excellent spatial resolution, detailed evaluation of lung parenchyma, and ability to identify alternative diagnoses 1.
• Recurrent or residual PE can be accurately detected, with central disease better identified on CT compared to conventional pulmonary angiography (accuracy 0.79 vs 0.74) 1.

Aortic Pathology

• CTA is the essential imaging tool for diagnosing aortic dissection with greater than 95% accuracy, providing excellent definition of the intimal flap, false and true lumens, and intra-aneurysmal thrombus 1.
• Aortic aneurysms are readily identifiable, with CTA defining maximal diameter and monitoring expansion over time 1.
• Traumatic aortic aneurysms, sinus of Valsalva aneurysms, and aortic coarctation can be diagnosed 1.
• Acute aortic syndromes are effectively detected, making CT the de facto clinical reference standard 4.

Coronary Artery Disease (ECG-Gated Studies)

• Coronary CT angiography (CCTA) demonstrates 90-95% or greater sensitivity and specificity for obstructive coronary artery disease when using dedicated ECG-gated protocols 5.
• CCTA has excellent negative predictive value (94-99%), making it highly effective for excluding significant coronary disease 6.
• The modality can diagnose atherosclerotic plaque, coronary stenosis, coronary dissection, and congenital coronary anomalies 1.
• CCTA provides information on plaque composition (calcified, non-calcified, mixed) and high-risk plaque features 6.
• Standard non-ECG-gated chest CTA lacks the temporal and spatial resolution for detailed coronary assessment 6.

Inflammatory and Infectious Vascular Conditions

Vasculitis

• CTA is 95% sensitive and 100% specific for diagnosing Takayasu arteritis, outperforming catheter-based angiography 1.
• Wall thickness measured by CTA is 67% sensitive and 98% specific for identifying giant cell arteritis 1.
• CTA demonstrates vessel wall thickness, stenoses, aneurysms, and extent of vascular involvement in Behcet disease 1.

Vascular Infection

• CTA demonstrates extent of vascular involvement, stenoses, aneurysms, wall thickening, and ulcers in vascular infections 1.
• Perivascular stranding, gas, and involvement of adjacent bony structures are identifiable 1.
• Rim enhancement (requiring IV contrast) is associated with infection requiring intervention 1.

Pulmonary Vascular Abnormalities

Pulmonary Hypertension

• Multidetector CT readily identifies findings associated with pulmonary hypertension 1.
• CT can demonstrate pulmonary artery enlargement and associated right heart changes 2.

Pulmonary Artery Aneurysms and Stenoses

• Various pulmonary vascular abnormalities including aneurysms and stenoses are detectable on CTPA 2.
• Pulmonary artery tumors (primary and metastatic) can be identified 2.

Additional Cardiac and Thoracic Findings

Pericardial Disease

• Pericardial effusions and thickening are readily identifiable on conventional and multidetector CT 1.

Non-Cardiac Chest Pathology

• Chest CT can identify conditions that may masquerade as cardiac disease, including pneumothorax, fractured ribs, pneumonia, and tumors 1.
• These conditions help exclude alternative diagnoses when evaluating chest pain 1.

Triple Rule-Out Protocol

Comprehensive Acute Chest Pain Evaluation

• Triple rule-out CTA can diagnose or exclude three life-threatening conditions in one examination: acute coronary syndrome, acute aortic syndrome, and pulmonary embolism 7.
• This protocol is efficient in emergency departments for patients with acute chest pain of uncertain etiology 7.
• TRO-CTA improves clinical evaluation and outcomes by differentiating between various etiologies of chest pain 7.

Technical Considerations and Limitations

Factors Affecting Diagnostic Accuracy

• Heavy coronary calcification limits assessment of stenosis severity and reduces specificity 6.
• High or irregular heart rates cause motion artifacts that can falsely suggest stenosis 6.
• Patient-related factors (obesity, inability to cooperate with breath-holding), technical factors (contrast timing, scanner parameters), and anatomic factors can cause misdiagnosis 3.
• The radiologist must determine study quality and identify which vessels are adequately evaluated versus indeterminate 3.

Radiation Dose Considerations

• Modern CCTA techniques have significantly reduced radiation exposure to 1.1-2.9 mSv using prospective triggering and iterative reconstruction 6.
• Radiation dose reduction strategies allow CT angiography to be performed in low-dose protocols in current clinical practice 8.

Common Pitfalls to Avoid

• Do not use standard non-ECG-gated chest CTA for detailed coronary artery assessment—dedicated coronary CTA with ECG-gating is required for accurate coronary evaluation 6.
• Recognize that calcium scoring indicates atherosclerotic burden but does not indicate plaque stability or functional significance of stenosis 9.
• Understand that anatomic stenosis on CTA does not always correlate with hemodynamic significance—functional testing may be needed for intermediate stenoses 9.
• Be aware that CCTA accuracy is compromised in patients with previous revascularization (stents, bypass grafts) due to blooming artifacts 9.