This document discusses coronary CT angiography (CCTA), a non-invasive imaging technique used to evaluate the coronary arteries. CCTA uses CT imaging with ECG gating to visualize the coronary arteries during periods of minimal cardiac motion. The document outlines the indications, contraindications, technical requirements, and procedure for CCTA. It describes how CCTA can be used to diagnose coronary artery disease, assess grafts after bypass surgery, and identify congenital coronary anomalies.

1. Coronary CT Angiography

2. • The coronary CT angiography
or cardiac CT angiogram
protocol:
• a non-invasive tool for the
evaluation of the coronary
arteries.
• The coronary arteries arise
from the aortic sinuses to
supply the myocardium of
the heart with oxygenated
blood.

4. Indications :
▪ congenital coronary artery anomalies
▪ coronary artery disease
▪ visualization of cardiac veins
▪ Evaluation of chest pain in patients at low to intermediate
pretest probability of disease.
▪ Pulmonary vein evaluation.
▪ Evaluation of cardiac masses.
▪ Evaluation of pericardial disease.
▪ Pre surgical evaluation, particularly before redo open heart
surgery.
▪ Assessing graft patency after prior bypass surgery.
▪ Evaluation of aortic disease.
▪ Evaluation of suspected pulmonary embolism.

5. CONTRAINDICATIONS:
❖ Renal insufficiency:
Given the potential for contrast nephropathy, patients with
significant renal insufficiency (i.e., Cr > 1.6 mg/dL) should not
undergo contrast enhanced CT.
❖ Known history of anaphylactic contrast reactions :
A prior anaphylactic response to contrast is generally felt to be
an absolute contraindication to intravenous iodinated contrast
administration at many institutions.
❖ Pregnancy
❖ Clinical instability
❖ Severe coronary calcium
❖ Inability to breath hold for at least 10 seconds.

6. Technical requirements:
✓ 64-slice scanner .
Multidetector computed tomography (MDCT) has rapidly evolved from 4-detector row systems in
1998 to 256-slice and 320-detector row CT systems :
With smaller detector element size and faster gantry rotation speed
spatial and temporal resolution of the 64-detector MDCT scanners have made
coronary artery imaging a reliable clinical test.
✓ detector element width ≤0.625 mm.
✓ option of cardiac CT and ECG-gated triggering .

7. Patient preparation
❖ patients should take their cardiac medications as usual .
❖ no food 3-4 hours before the scan .
❖ no caffeine for 12 hours Consuming caffeine can make the heart beat
faster, which will interfere with the imaging test. Prior to the test, we ask
that people avoid caffeinated food or beverages, including: coffee .
❖ instruction on how to breathe (breath hold is recommended )
❖ an electrocardiogram signal needs to be acquired
❖ heart rate control

8. Premedication
❖ check heart rate and blood pressure before administration
of medications .
❖ administration of nitrates (400-800 µg of sublingual
nitroglycerin e.g. 1-2 sprays) .
❖ administration of ß-blocker (to target pulse of ≤60 bpm)
o e.g. metoprolol 50-100 mg one hour before the exam
o e.g. metoprolol 5mg iv followed by monitoring for 5 min
repeatedly up to 15-20 mg

9. • Electrocardiography?
• Electrocardiography is the process of producing
an electrocardiogram .
• a recording of the heart's electrical activity.
• It is an electrogram of the heart which is a graph
of voltage versus time of the electrical activity of
the heart using electrodes placed on the skin

10. ECG GATING Mechanism :
• First, the skin is cleaned.
• Up to 12 self-adhesive electrodes will be attached
to select locations of the skin on the arms, legs
and chest.
• Three ECG leads are attached to obtain an adequate
ECG tracing for CT.
• A noise-free ECG signal is important to synchronize
theECG signal to the raw image data.

11. Technique
• patient position
supine with both arms above their head (as comfortably as
possible)
ECG placement
• tube potential
100 kVp if patient’s weight ≤100kg or BMI <30kg/m2
• tube current
use automated current adjustment mode
• scout
pulmonary apices to below the heart
• scan extent
o ideally to be determined by calcium scoring
o just below tracheal bifurcation to below the heart
• scan direction/craniocaudally

12. retrospective ECG gating?
Retrospective gating acquires images continually throughout
the cardiac cycle and simply pieces together
images from the desired phase (typically diastole for anatomic
imaging) after the entire scan is completed.
What does retrospective mean in CT?
A retrospective ECG-gated cardiac CT is usually conducted
in cases in which adequate control of heart
rate cannot be achieved or in which additional information on
ventricular or valvular function is
Required
. Retrospective gating collects data continuously then
groups and fills k-space according to the
phase of the cardiac cycle.

13. prospective ECG triggering?
Prospective ECG-triggered coronary CT angiography uses the
partial-scan technique to the motion of the heart, which is
defined as the step-and-shoot method, so that scan is triggered
by ECG signal instead of spiral CT acquisition .
Prospective cardiac gating (triggering) acquires data
during a specific acquisition window between R waves

14. CT volume rendering?
➢ Volume rendering is a type of data visualization technique
which creates a three-dimensional representation of data.
Calcium Scoring
A coronary CT calcium scan is a computed tomography
scan of the heart for the assessment of severity of
coronary artery disease. Specifically, it looks for calcium
deposits in atherosclerotic plaques in the coronary
arteries that can narrow arteries and increase the risk of
heart attack
The score reflects the total area of calcium deposits and
the density of the calcium.

15. a good score for calcium scoring
A calcium score of 0 means there is no evidence of heart
disease.
1-10 is for minimal evidence of heart disease.
11-100 is for mild evidence of heart disease.
101-400 is for moderate evidence of heart disease
agatston calcium score
The result of the test is usually given as a number .
The score reflects the total area of calcium deposits and the
density of the calcium.
A score of zero means no calcium is seen in the heart.
It suggests a low chance of developing a heart attack in the
future .

16. CCTA of a 61 year old women. A) 3D volume rendered reconstruction of the heart and the coronaries. The coronary
arteries can be seen in the 3D reconstruction. B) Reconstruction of the right coronary artery (RCA) without CAD. C)
Reconstruction of the left anterior descending artery of the same patient, also without stenosis. D) Circumflex (CX)
reconstruction, not showing any disease.

17. Patient with a coronary anomaly. A) The anomalous left coronary artery arises from the proximal RCA,
through the septum into the LAD. B) Maximum intensity projection of the anomalous left coronary artery.

18. Evaluation after bypass-surgery, same patient as in figure 4. A) The distal left internal mammary artery (LIMA)
is anastomosed with the proximal LAD at the location of the former anomalous left coronary artery. B) The
graft and distal LAD show good contrast filling.