Cardiac CT-CCTA involves three main steps: patient preparation with beta blockade and nitroglycerine to lower heart rate, initial calcium scoring to identify atherosclerotic vessels, and coronary CTA scan using retrospective or prospective ECG gating. CCTA allows visualization of the coronary arteries and quantification of plaque type and stenosis. Normal coronary anatomy includes the left main artery bifurcating into the LAD and LCX, and the RCA originating from the right coronary cusp and dominantly supplying the posterior descending artery in most cases.

1. Cardiac CT-CCTA
Dr.Sahar Gamal El-Din ,CBCCT
National Heart Institute

2. Performing CCT

3. Patient Preparation:
Ensure patient comfort
•Explain breathing instructions clearly
•Discuss contrast effects
•Antecubital IV 18-20g suggested
•Beta-blockade
•Target heart rate 50-65 bpm
•Nitroglycerine

4. Initial Scanning: Ca Score
1. Helps to identify how the coronary
vessels will behave (especially the RCA)
during the scan.
2. Points out the “ possible” atherosclerotic
vascular tree.
3. High Ca score is not equivalent to “not to
perform the test ( but be wise ).

5. Coronary Disease Progression
Calcified Plaque Detected by CT

6. • Atherosclerosis is the only disease
process known to cause calcium to
deposit in coronary artery walls.
• Calcification is not a degenerative
disease, it is not a part of the “normal”
aging process.
• Calcium is not found in normal CA.
Radiology 2002; 223:474–480.

7. • Since calcium deposits start to develop
during the early stages of atherosclerosis
and if we are able to identify the
presence of calcium we are able to
identify preclinical coronary artery
disease during the asymptomatic stage.
• This can allow for the implementation of
early aggressive risk factor reduction.

8. • Coronary artery calcification has been
shown to be a marker for coronary artery
atherosclerosis .
• Calcification can be seen with fluoroscopy
and on chest x-ray.
• Computed tomography allows
quantification of this calcium.

9. • The amount of calcium deposited in
coronary arteries is added up and a “score” is
given.
• The amount of calcium in the coronary
arteries varies considerably with age and
gender.
• For this reason, coronary calcium scores are
presented as percentile scores telling you
how much calcium you have compared to
other men or women of your age.

10. Methods
• Agatston Score :Traditional method
(EBCT : MDCT)
• Volume Score : Plaque area x slice
thickness (mm³)
• Mass Score : Plaque volume x mean
plaque density .

13. The Calcium Scale
The calcium scale is a linear scale with 5
calcium score categories:
0 none
1–99 mild
100–400 moderate
>400 severe
>1000 extensive calcification

14. Image acquisition and
reconstruction

15. • The acquisition of the dataset for coronary
CTA consists of 3 steps :
1. Topogram
2. Contrast medium protocol : to ensure
homogeneous contrast enhancement of the
entire coronary artery tree
3. Coronary CTA scan

16. Topogram
• Native coronary arteries
# Begin 1–2 cm below the carina
# Tortuous aorta or prominent
upper left heart border – begin
scan 1-2cm higher
• Bypass Grafts
 Veins: top of arch
 LIMA: above clavicles
Scan ending position
• Image acquisition end 2 cm
below the diaphragm
Scan Start Position

17. Contrast Injection
1. Iodine Content
2. Volume
3. Rate
4. Synchronization Techniques:
a. Fixed Delay
b. Test Bolus
c. Bolus Tracking

18. Phase Synchronization
1.Retrospective ECG gating (Continuous
Scanning).
2.Prospective ECG triggering (step-and-shoot
technique).

19. Retrospective ECG gating
• The most commonly used data
reconstruction technique
•Advantage: any desired phase of the
cardiac cycle can be reconstructed
•Disadvantage: increased radiation dose

20. Prospective ECG gating
 Data are only acquired at predefined time points
of the cardiac cycle when the data acquisition is
considered relevant.
The X-ray tube is turned on at a priori chosen time
interval from the last monitored R–R peak.
Advantage: dcreased radiation dose
Disadvantage: limited information & no function

21. Scanning protocol

22. Post processing protocol
• The axial source images obtained are utilized for
multiplanar reconstructions in at least 2 planes
• Commonly used techniques are :
 Multiplanar reconstruction (MPR)
 Curved planar reconstruction (CPR)
 Maximum intensity projection (MIP)
 Volume rendering (VR)

23. Multiplanar reconstruction (MPR) Curved MPR reconstruction (CMPR)
Maximum intensity projection (MIP)VRT reconstruction image

24. Anatomy & Views

25. Axial Sagital
Coronal

42. Normal Coronary Anatomy
• Left Coronary Artery and its Branches :
• The left main artery normally arises from the
posteriorly positioned left sinus of Valsalva and
bifurcates into the LAD & LCX .
• The LAD courses through the anterior
interventricular groove and provides diagonal
branches to the anterior left ventricle and septal
branches to the anterior interventricular
septum.

43. LMT

44. • The LCX gives off obtuse marginal branches
(OM), which supply the lateral wall of the left
ventricle.
• Occasionally, the left main artery can trifurcate
into the LAD, the LCX, and a third vessel
between the LAD and LCX termed the ramus
intermedius artery.
• The course and vascular territory of the ramus
intermedius artery are similar to those of the
diagonal and/or obtuse marginal arteries.

45. OM
Diag.
LMT

47. Different types of LMCA bifurcation.
Oblique transverse thin-slab maximum-intensity projection images.
The LMCA is shown bifurcating into the LAD and LCX (Panel A),
the LM with trifurcation into the LAD and the LCX, and in between an
intermediate branch (IMB, Panel B). Note the high diagonal branch (D)
from the LAD (Panel B).

48. Curved MPR of LAD

49. Curved MPR of LCX

50. • Right Coronary Artery and its Branches:
• The RCA arises from the anteriorly positioned
right sinus of Valsalva and courses through the
right AV groove.
• The conus artery is the first branch of RCA in
50% of cases, and it supplies the right
ventricular infundibulum. In the remaining
50% of cases, the conus artery arises directly
from the aorta.
• The sinoatrial (SA) nodal branch arises from the
RCA in most patients (60%) & courses
posteriorly. In the remaining patients it arises as
a branch of the LCX.

51. • Other branches supply the right atrium and
free wall of the right ventricle.
• The largest of these arises from the RCA at the
acute margin of the heart and is termed the
acute marginal branch.
• At the crux of the heart the RCA gives off the
posterior descending artery ( PDA ), which
supplies the posterior interventricular septum.
• The posterolateral branch (PLB) is a
continuation of the RCA in the posterior
atrioventricular groove & supplies the
posterior and inferior wall of the LV

52. PL

55. Curved MPR of RCA

56. Maximum intensity projection (MIP) of RCA

60. Dominance
• Generally, the artery that supplies the inferior
1/3 of the interventricular septum is considered
to be the dominant coronary artery.
• The RCA is dominant in most subjects (85%),
while in 7% to 8% of cases the LCX gives rise to
the posterior descending artery (PDA), a left
dominant system.
• In the remaining patients, a codominant, or
balanced circulation, system exists; examples
include a small PDA originating from the RCA
with posterolateral branches from the LCX
artery, and PDAs from both the RCA and LCX.

61. PL
Rt.Dominant

62. RCA
LCX
Lt.Dominant Co.Dominant

63. • The coronary artery nomenclature is based
on the intermediate and distal vascular
territory of the artery; this is particularly
important when vessels are anomalous.
• In these circumstances, the proximal
course or coronary origin cannot be
considered when defining or naming the
respective coronary artery.

64. • For example, a subepicardial artery that courses
through the anterior interventricular groove
and provides septal branches is termed the
LAD, regardless of its origin from the aorta.
• Similarly, for an artery to be defined as the
LCX, it should course through the left
atrioventricular sulcus and provide at least one
obtuse marginal (OM) branch.
• The RCA is defined as an artery that runs in
the right atrioventricular sulcus and gives off
RV or acute marginal branches.

65. Coronary artery assessment
• The best evaluated coronary artery is the LAD
as it runs along the axis of the scan and is not
significantly affected by cardiac movements.
• The LAD is well visualized in 76-96% of cases
• The left CX artery may be affected by cardiac
motion artifacts and can be assessed in 52-95%
of cases.
• RCA is most affected by cardiac movement
• Proximal coronary segments are better
visualized than distal ones.

66. Normal Coronary Artery Diameter
– Each coronary artery vary, ranging from
5 mm (LMT in males) to 2 mm (PDA in
females).
– Abnormal dilatation to more than 1.5
times the diameter of an adjacent normal
coronary artery is defined as ectasia.

68. Coronary artery aneurysms
• Classification :
• Vessel wall composition
• True aneurysm Vessel wall composed of three layers:
adventitia, media, and intima
• False aneurysm Vessel wall composed of one or two
layers
• Shape/gross structure
• Saccular aneurysm Transverse > longitudinal diameter
• Fusiform aneurysm Longitudinal > transverse diameter
• Giant aneurysm
• Adults >20 mm–150 mm in diameter
• Children >8 mm in diameter

70. Types of plaques
1. Non-calcified
2. Partly calcified
3. Mixed
4. Calcified
• Positive remodelling : outward plaque
growth leading to arterial wall expansion
in an attempt to avoid luminal stenosis.
Eccentric - Concentric

71. Recommended stenosis grading
• Normal : Absence of plaque & no
luminal stenosis.
• Minimal : Plaque with < 25% stenosis.
• Mild : Plaque with 25% to 49 stenosis.
• Moderate : Plaque with 50% to 69
stenosis.
• Severe : Plaque with 70% to 99 stenosis.
• Occluded.
JCVCT 2014;342-358