CT Coronary Angiography Overview

CT Coronary Angiography

• Purpose (Morphology): Detects and analyzes coronary artery disease, depicting coronary artery anatomy. Also assesses myocardial function in the same scan.
• Purpose (Function): Measures myocardial contractility and valve morphology/function, assessing myocardial viability.
• Indications: Evaluates suspected pulmonary embolism, aortic disease, pericardial disease, cardiac masses, and pre-surgical heart surgery (especially before redo open-heart surgery), and pulmonary veins. Also used for patients with low-to-intermediate chest pain and suspected coronary artery anomalies or complex congenital heart disease, or assessing graft patency after bypass surgery.
• Contraindications: Pregnancy, clinical instability, insufficient renal function, and a history of anaphylactic contrast reaction.

Patient Preparation

• Medications: Patients should take cardiac medications as usual. Nitrate and beta-blocker contraindications should be checked.
• Diet: No food 3–4 hours before the scan. No caffeine for 12 hours.
• Other: Instructions on breathing, ECG signal acquisition, and heart rate control are necessary.

Prospective ECG Method

• Purpose: Captures high-quality heart images with minimal motion artifacts, synchronized with ECG. Specific points in the cardiac cycle (mid-to-end diastole) are used.
• Advantages: Lower radiation exposure, short scan period, and high-quality diagnostic images without needing the complete cardiac cycle.
• Limitations: Requires a regular sinus rhythm, less effective for patients with high heart rates or arrhythmias; patient weight should be under 100kg.

Retrospective ECG GATED Method

• Purpose: Used when heart rate control is difficult or additional information about ventricular/valvular function is needed.
• Procedure: Images are acquired continuously throughout the entire cardiac cycle, and the best image is selected from the different phases.
• Advantages: Provides information about heart function in patients with irregular heart rates or high heart rates.
• Disadvantages: Higher radiation exposure.

Contrast Injection

• Biphasic Injection: Used to evaluate the RCA and for functional analysis. Used to opacify the right ventricle.
• Triphasic Injection: Used to maintain dense opacification for coronaries and the left ventricle, and good opacification improvement to the right ventricle.

Post-Processing Techniques

• Techniques: Multiplanar reformats (MPR), maximum intensity projections (MIP), volume rendering (VR), curved reformats, and cine imaging.

Calcium Score

• Purpose: Useful risk stratification tool for coronary artery disease. Also is better than other risk assessment methods when it comes to cardiovascular events and death prediction.
• Scoring: Calcium density is assessed, from 1 to 4.
• Limitations: Irregular heart rates and obesity limit the value of the procedure's usefulness.

CT Anatomical Planes of the Heart

• Planes: Vertical long axis, short axis views, three-chamber view, and four-chamber (or horizontal long axis).