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Cardiac ❯ Coronary Artery Disease

ProblemSuspected coronary artery disease

The cardiac CTA protocol will vary depending on what type of CT scanner you have ranging from a 64 slice scanner to a photon beam scanner. The goal of a cardiac CT exam is a well timed study with all the coronary arteries opacified with contrast and a lack of motion related artifacts. The faster the scanner is the easier it is to get a quality study. Some of the key factors are listed below.

  1. We routinely will always do a non contrast CT scan first for calcium scoring. This will help with risk analysis as well. Some sites will not do a coronary CTA with an Agaston score of 1000 or better. The higher the calcium score, the harder is it to get a quality CTA study. Although people talk about cutoff scores most sites will complete the study
  2. Ideally heart rates around 60 BPM are ideal for a CTA. A low heart rate and a steady heart rate are critical. Most sites use beta blockers as well as nitroglycerin to optimize the study
  3. The scan volume for a routine coronary CTA is from the subcarinal zone to the heart apex
  4. Both the pitch and the scan time will vary based upon the patient's heart rate. 100 kVp is used for most average size patients. ECG dose modulation is always performed to limit patient exposure
  5. Contrast volume is usually 60-80 cc followed by a 30 cc saline flush. Injection rate is 5-6cc/sec
  6. Bolus tracking is performed off the ascending aorta using a 230 HU trigger setting.
  7. Images are usually reconstructed with .75 mm slice thickness at .5 mm intervals
  8. Post processing of the CT data is critical and at a minimum curved planar reconstruction (CPR) is mandatory to isolate each coronary artery. Interactive display of the coronary arteries by the radiologist is ideal to detect and quantify the presense of coronary artery disease.
  9. The future will likely see AI help with analysis of coronary artery disease and subsequent management decisions.

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