1. Heart Rate Control
“First number is a 5” Lopressor 5-15 mg IV and/or Metoprolol 50-100mg PO (do not use XL)
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2. ECG Gating
The CT and ECG data is acquired simultaneously. The R-R interval is divided into segments. The number of segments and the naming of segments varies according to the vendor.
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3. Field of View (FOV)
Scanning is performed from cranial to caudal. For native coronaries, begin at the carina. For bypass graft analysis, the FOV is extended to include the internal mammary arteries (shown in white).
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4. MDCT Scanning
In general, highest number of rows, thinnest slices, and fastest gantry rotation. (This is always true when the “First number is a 5”.) Parameters: 550 mAS, 120 KV, pitch ~0.3.
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Calcium Scoring, Noncontrast MDCT Protocol
Calcium Scoring, Noncontrast MDCT Protocol
ECG gated; 3 mm collimation, 1.5mm reconstruction. 150mAs, 120 kV. Dose reduction can be achieved with ECG pulsing. Scan includes lungs and mediastinum. Semi-automated computation of the Agatson score. Radiologist reviews Agatson score, lungs, and mediastinum.
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5. Contrast
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Iodine concentration = 370mg/cc. Dual injection: contrast/saline. Saline injection intended to reduce artifact from contrast within cardiac chambers. Injection rate= 5cc/sec. Contrast volume determined by duration of image acquistion; e.g. 18 sec acquisition uses 90cc (18sec x 5cc/sec) contrast. Test Injection vs. Automated. For the test injection bolus, add 3 seconds to the delay time to allow for coronary opacification.
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6. Image Reconstruction using a small segment of ECG tracing.
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