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CT Coronary Angiography

Coronary CT angiography is a non-invasive, ECG-synchronized study that visualizes the coronary artery lumen and wall, enabling detection and grading of stenosis and characterization of atherosclerotic plaque. It has a very high negative predictive value, making it an excellent gatekeeper to exclude significant coronary artery disease in patients with stable or acute chest pain and low-to-intermediate risk. Adequate heart-rate control and rhythm are essential for diagnostic image quality.

Indications

Stable chest pain with low-to-intermediate pretest probability of coronary artery disease
Acute chest pain in the emergency department to exclude significant CAD (with low-intermediate risk)
Assessment of suspected coronary anomalies or origin/course of anomalous vessels
Evaluation of coronary artery bypass graft patency and complex percutaneous intervention planning
Equivocal or inconclusive functional/stress testing
Pre-procedural planning (e.g., before valve intervention such as TAVI) and coronary calcium scoring for risk stratification

Contraindications & Cautions

Iodinated contrast allergy (premedicate) and significant renal impairment (weigh contrast risk)
Uncontrolled tachycardia or arrhythmia (e.g., atrial fibrillation) limiting gating quality
Inability to hold breath or cooperate; severe obesity may limit image quality
Contraindications to rate-controlling beta-blockers (severe asthma, decompensated heart failure, high-grade AV block) and to nitrates (hypotension, PDE5-inhibitor use)
Pregnancy: justify and dose-optimize; generally deferred unless essential
Extensive coronary calcification may cause blooming and reduce diagnostic accuracy

Patient Preparation

Screen renal function, contrast allergy, pregnancy, and current medications (PDE5 inhibitors)
Achieve target heart rate (typically <60-65 bpm) with oral and/or IV beta-blockade per protocol
Administer sublingual nitroglycerin immediately before acquisition to dilate coronaries (if not contraindicated)
Avoid caffeine before the study; establish large-bore (18-20 G) right antecubital IV access
Attach ECG leads, coach breath-hold, and confirm regular rhythm before scanning
Explain the procedure and obtain consent; keep resuscitation facilities available

Technique & Parameters

ECG-gated acquisition: prospective (axial, low-dose) for stable low heart rates, retrospective (helical) when function or arrhythmia handling is needed
Submillimeter collimation (0.5-0.75 mm) for high spatial resolution of small coronary vessels
IV contrast ~50-80 mL of high-concentration iodinated agent at 5-6 mL/s with saline chaser; bolus tracking in the aortic root
High-pitch or wide-detector single-heartbeat acquisition where available to minimize dose and motion
Coverage from the carina/tracheal bifurcation to below the diaphragm to include grafts when relevant
Reconstruct multiple cardiac phases; use MPR, MIP, and curved reformats for vessel analysis; perform Agatston calcium score on a non-contrast gated series

Systematic Review

Assess overall image quality, contrast opacification, and motion/step artifacts before interpretation
Evaluate coronary dominance and origins; identify any anomalous origin or course
Analyze each segment (per SCCT/AHA model) for stenosis severity and plaque
Characterize plaque as calcified, non-calcified, or mixed and note high-risk features
Review bypass grafts and stents for patency, occlusion, or in-stent restenosis (allowing for blooming)
Assess cardiac chambers, myocardium, valves, and pericardium within the field
Review the aorta, pulmonary arteries, and lung bases/mediastinum for non-coronary findings

Key Findings & Significance

Luminal stenosis graded by CAD-RADS (minimal, mild, moderate, severe, occluded)
Non-calcified or mixed plaque with positive remodeling and low attenuation: higher-risk plaque
Napkin-ring sign and spotty calcification: vulnerable plaque features
High Agatston calcium score correlating with atherosclerotic burden and cardiovascular risk
Anomalous coronary origin with an interarterial course: potentially high-risk anomaly
Graft occlusion or stenosis and in-stent restenosis
Myocardial hypoperfusion, aneurysm, or thrombus as ancillary findings

Differential Considerations

Apparent stenosis: true atherosclerotic narrowing vs calcium blooming vs motion artifact
Filling defect in a graft/vessel: thrombus/occlusion vs poor opacification/mixing artifact
Non-calcified plaque vs coronary vessel wall thrombus vs myocardial bridging (dynamic narrowing)
Chest pain with normal coronaries: microvascular disease, myocarditis, pericarditis, or non-cardiac cause
High calcium score with unassessable lumen: consider functional testing or invasive angiography
Anomalous vessel: benign course vs malignant interarterial course requiring further evaluation

Pearls & Pitfalls

Heart-rate and rhythm control are the single biggest determinants of diagnostic quality
Dense calcification and stents cause blooming that overestimates stenosis; state when segments are non-evaluable
Report using standardized CAD-RADS to guide downstream management
Myocardial bridging is common and usually benign but should be reported when the tunneled segment is deep/long
Always look beyond the coronaries: pulmonary emboli, aortic dissection, and lung pathology may explain symptoms
Motion artifact typically affects the right and distal circumflex arteries; reconstruct alternative phases

Structured Report

State protocol, gating method, heart rate, contrast, and image quality/evaluability
Report coronary dominance, anomalies, and per-vessel/segment stenosis with CAD-RADS category
Characterize plaque type, burden, and high-risk features; include calcium score
Comment on grafts, stents, chambers, valves, and pericardium
Note non-coronary/incidental thoracic findings
Impression: overall CAD severity (CAD-RADS), management implication, and follow-up or further testing recommendation

References

SCCT Guidelines for Performance and Interpretation of Coronary CT Angiography
CAD-RADS 2.0 Reporting and Data System (SCCT/ACR/NASCI)
ACC/AHA Guideline for the Evaluation and Diagnosis of Chest Pain
ACR Appropriateness Criteria: Chest Pain - Suspected Coronary Artery Disease

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CT Coronary Angiography

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References