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A Pictorial Review of Coronary Artery
Anatomy on Spiral CT*
David N. Rabin, MD; Steven Rabin, MD; and Richard A. Mintzer, MD, FCCP
Coronary artery calcification quantification (scoring) has been done with electron beam CT
(EBCT), but is now being done with spiral or helical CT. Many radiologists and cardiologists who
do not have EBCT but do have access to spiral CT will now be able to do coronary artery
calcification scoring, and will now need to know the spiral CT appearance of the coronary artery
anatomy. This pictorial review will demonstrate the anatomy needed for coronary artery calcium
scoring.
(CHEST 2000; 118:488 – 491)
Key words: calcinosis; calcium; coronary arteriosclerosis; coronary artery disease; coronary stenosis; coronary vessels
Abbreviations: EBCT ⫽ electron beam CT; LAD ⫽ left anterior descending artery; LCX ⫽ left circumflex artery;
LMA ⫽ left main coronary artery; PDA ⫽ posterior descending artery; RCA ⫽ right coronary artery
lectron beam CT (EBCT) has been used for
E years
to quantify coronary artery calcification,
although the clinical utility of screening for coronary
artery calcification is still controversial. Coronary
artery calcification quantification is now starting to
be done with spiral CT technology. Spiral CT for
coronary artery calcification scoring will change this
formerly esoteric technique into a common and
perhaps almost universally available screening test.
Knowledge of coronary artery anatomy as seen on
spiral CT is now becoming important to radiologists
and cardiologists, since spiral CT is commonly available and EBCT is expensive and has limited availability. This review article will demonstrate the
coronary artery anatomy as seen on spiral CT. The
images have been obtained with a CT/i Spiral CT
scanner (General Electric; Milwaukee, WI). These
images demonstrate the image quality that can be
*From the Northwestern University Medical School (Drs. D.
Rabin and Mintzer), Highland Park Hospital, Highland Park; and
Loyola University Chicago (Dr. S. Rabin), Maywood, IL.
General Electric paid another institution for electron beam CT
studies and paid Highland Park Hospital for some spiral CT
studies so that we could compare spiral CT and electron beam
CT results in a current research study.
Manuscript received September 9, 1999; revision accepted December 29, 1999.
Correspondence to: David N. Rabin, MD, Northwestern University Medical School, Highland Park Hospital, 718 Glenview Ave,
Highland Park, IL 60035
expected from routine spiral CT evaluation of the
coronary arteries using special cardiac imaging software (Smartscore; General Electric).
Evaluation of the coronary arteries is performed
with images from near the carina of the lung to the
bottom of the heart. Each rotation of the scanner
attempts to capture data for one 3-mm image. The
acquisition technique is selected as a function of
heart rate and CT-scanner rotation speed, such that
the table advances by 3 mm in each heartbeat. From
the acquisition images, the software creates reconstructed images every 0.1 s or 0.3 mm, so that 10
reconstructed images span each cardiac cycle. The
study is retrospectively gated with the patient’s
ECG, which was obtained during the image acquisition. Diastolic images are selected from the reconstructions, so that images used in coronary artery
calcification scoring have the least amount of motion,
since motion blurring would increase the apparent
size and score of calcium. Heart rates ⬎ 90 beats/min
are currently not scanned. Misregistration artifact is
decreased by acquiring the images in the same part
of the cardiac cycle.1
Coronary artery calcification quantification is then
performed on selected diastolic reconstructions using
Smartscore at a workstation. Early reports indicate that
coronary artery calcification quantification of retrospectively cardiac gated spiral CT are highly correlated with
the results obtained from EBCT.2
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Figure 1. LMA (arrow) in a 37-year-old man; A ⫽ aorta.
Figure 3. Branch of the LAD (arrowhead) in a 48-year-old man.
Coronary artery calcification scoring requires a
thorough understanding of the anatomy of the coronary arteries that are evaluated in the study. Coronary artery calcium quantification is performed for
the left main coronary artery (LMA), left anterior
descending artery (LAD), left circumflex artery (LCX),
right coronary artery (RCA), and the posterior descending artery (PDA). These are all easily recognized
using these special spiral CT techniques. We trace each
individual coronary artery from its origin to the inferior
aspect of the heart on contiguous images.
The first coronary artery seen (starting superiorly
from its origin) is the LMA. The LMA arises from
the left sinus of Valsalva (Fig 1) and courses to the
left posterior to the main pulmonary artery. The
LMA bifurcates into the LAD and the LCX (Fig 2).
The LAD runs anteriorly in the anterior interventricular groove. The LAD gives off septal and diagonal branches (Fig 3), and we quantify the calcium
seen in branches of the coronary arteries. Septal or
diagonal calcium would be counted as calcium in the
LAD. The LCX runs to the left and inferiorly in the
posterior atrioventricular groove (Fig 4).3 The LCX
gives off marginal branches, which supply the left
ventricle.
The RCA originates more caudally from the aorta
than the LMA. The RCA arises from the right sinus
of Valsalva (Fig 5). The RCA runs anteriorly and to
the right, and then courses inferiorly. The RCA runs
in the anterior atrioventricular groove. The RCA and
LCX can be followed inferiorly toward the apex of
the heart (Fig 6, top and bottom).
The PDA usually arises from the RCA. Coronary
artery dominance is defined by which coronary
artery gives rise to the PDA. The RCA is dominant in
70% of people with the RCA giving rise to the PDA
(Fig 7). In 10% of people, the left coronary artery is
dominant, and the LCX reaches the crux of the heart
and continues as the PDA. In 20% of people, there
is a balanced system in which the RCA gives rise to
Figure 2. Bifurcation of the LMA into the LAD (arrow) and the
LCX (arrowhead) in a 52-year old woman; V ⫽ right ventricular
outflow; L ⫽ left atrium. See Figure 1 for other abbreviation.
Figure 4. Calcification is seen in the LCX (arrow) and RCA
(wavy arrow) in a 62-year-old woman.
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Figure 5. Origin of the RCA (arrow) in a 57-year-old man. The
LCX (curved white arrow) is also seen; A ⫽ ascending aorta;
R ⫽ right atrium; V ⫽ right ventricle; D ⫽ descending aorta. See
Figure 2 for other abbreviation.
Figure 7. RCA (arrowhead) giving rise to the PDA is near to a
coronary vein (curved arrow) in a 54-year-0ld woman. The
coronary vein could be traced back on contiguous images to the
coronary sinus.
the PDA, but the LCA also supplies branches which
supply this area of the left ventricle. The LCA
supplies the majority of blood to the left ventricle,
even in people who have a right dominant system.4
The PDA extends to the apex of the heart in the
posterior interventricular groove, and frequently meets
branches of the LAD at the apex of the heart.
There are potential pitfalls when using CT to evaluate coronary artery anatomy. The LAD may extend
above or in a cephalic direction, so that portions of the
LAD may be more cephalic than the LMA (Fig 8). If
this is not recognized, then calcification in this part of
the LAD will not be scored, resulting in a score that is
incomplete and potentially misleading. Coronary veins
may be confused with coronary arteries (PDA; Fig 9) at
the caudal aspect of the heart. These vascular structures, however, can be traced back to the coronary
sinus on contiguous images, proving that they are veins.
Spiral CT can demonstrate coronary artery anatomy and can demonstrate coronary artery calcification (Fig 5) when the coronary artery anatomy is
understood.
Figure 6. Top and bottom: RCA (arrowhead), LCX (solid arrow),
and LAD (open arrow) running inferiorly toward the apex of the
heart in a 48-year-old man.
Figure 8. Cephalic portion of LAD (curved arrow) in a 60-yearold woman; P ⫽ right pulmonary artery.
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References
1 Woodhouse CE, Janowitz WR, Viamonte M Jr. Coronary
arteries: retrospective cardiac gating technique to reduce
cardiac motion artifact at spiral CT. Radiology 1997; 204:
566 –569
2 Carr J. Coronary artery calcium scores correlate strongly
between fast gated helical and electron beam computed
tomography. Paper presented at: American Heart Association’s Epidemiology and Prevention Conference. March,
1999; Orlando, FL
3 Kubicka RA, Smith C. How to interpret coronary arteriograms. Radiographics 1986; 6:661–701
4 Sos TA, Sniderman KW. A simple method of teaching
three-dimensional coronary artery anatomy. Radiology 1980;
134:605– 606
Figure 9. RCA gives rise to the PDA, which demonstrates
minimal calcium (curved arrow), and the PDA is adjacent to a
coronary vein (arrow) in a 49-year-old man.
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