CT CORONARY ANGIOGRAPHY


🫀 CT Coronary Angiography (CTCA)

✅ Definition

CT Coronary Angiography is a  imaging technique that uses multi-detector computed tomography (MDCT) and intravenous iodinated contrast to obtain detailed 3D images of coronary arteries, used primarily to detect coronary artery disease (CAD).



📌 Indications

CTCA is typically used for:

  • Atypical or non-specific chest pain
  • Low to intermediate risk of CAD
  • Equivocal or inconclusive stress test
  • Evaluation of coronary artery anomalies
  • Assessment of coronary bypass grafts
  • Pre-operative cardiac evaluation (e.g., before major surgery)
  • Follow-up of stents (with limitations)

⚠️ Contraindications

Absolute:

  • Severe allergy to iodinated contrast
  • Severe renal impairment (eGFR <30 mL/min/1.73 m²)
  • Pregnancy (unless absolutely necessary)
  • Uncontrolled arrhythmias
  • Inability to cooperate or hold breath

Relative:

  • High heart rate (>100 bpm)
  • Severe obesity (may degrade image quality)
  • Claustrophobia
  • Thyrotoxicosis or untreated hyperthyroidism

🧑‍⚕️ Patient Preparation

  • Fasting: 4–6 hours before the scan
  • Heart rate control: Beta-blockers may be given (target HR <60 bpm)
  • Nitroglycerin: Sublingual nitrate to dilate coronary arteries
  • Renal function test: Assess creatinine/eGFR
  • Contrast allergy history: Check prior to exam
  • Remove metallic items: Especially around chest

💉 Contrast Technique

  • Type: Non-ionic iodinated contrast
  • Volume: 50–100 mL (varies by patient and scanner)
  • Injection rate: 4–6 mL/sec via large-bore IV cannula (18–20G)
  • Saline flush: 30–50 mL to optimize contrast delivery and reduce artifacts.

   ✍️ Summary Table

ParameterDescription
ROI LocationAscending Aorta
HU Threshold~100–150 HU
Trigger Delay3–6 seconds after threshold
MethodBolus tracking (automatic) or test bolus (manual equation

🧪 Method / Procedure

  1. Patient positioned supine, arms above head
  2. ECG electrodes applied for synchronization (gating)
  3. Scout scan to define scan range
  4. Optional calcium scoring (non-contrast scan)
  5. Bolus tracking or test bolus to time the contrast.
  6. ROI - Ascending Aorta 
  7. Breath-hold during image acquisition
  8. ECG-gated CT scan:
    • Prospective gating: lower dose, snapshot timing
    • Retrospective gating: continuous scan, higher dose
  9. Post-processing: 3D reconstruction, MPR, curved MPR, volume rendering                        

  11. In CT Coronary Angiography (CTCA), the imaging produces multiple reconstructed views or films for thorough evaluation of the coronary arteries. These "films" (or images) are typically viewed and interpreted in various standardized formats to accurately assess coronary anatomy and pathology.

    📸 Typical Films (Image Views) Taken in CTCA 

    Film Type Purpose
    Axial Image Basic anatomy and pathology
    MPR (Coronal, Sagittal) Assess course and orientation
    Curved MPR of LAD Evaluate stenosis, plaque along LAD
    Curved MPR of RCA Trace full RCA pathway
    VRT 3D View Overall visualization of coronary tree
    MIP Image Slabs Highlight calcification or vessel continuity.

🩺 Aftercare

  • Monitor for 15–30 minutes post-scan (contrast reactions)
  • Hydration to flush contrast from kidneys
  • Resume normal diet and medications
  • Watch for delayed allergic reactions

🧬 Diseases Diagnosed

  • Coronary artery disease (CAD)
  • Coronary artery stenosis or occlusion
  • Anomalous origin or course of coronary arteries
  • Myocardial bridging
  • Atherosclerotic plaque (calcified, non-calcified, mixed)
  • Coronary aneurysms
  • Bypass graft patency
  • Stent evaluation (limited by resrendering.
  •                              
  •                                ******* 

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