1) MDCT provides detailed images of coronary artery anatomy and is useful for evaluating common coronary pathologies. 2) The coronary arteries normally arise from the sinuses of Valsalva and have variable branching patterns. MDCT helps distinguish benign variants from potentially dangerous anomalies. 3) Coronary artery anomalies can involve abnormal origins, courses, or terminations and in some cases may lead to ischemia or sudden cardiac death. MDCT is well-suited to characterize these anomalies.

1. Multi detector CT in
coronary artery disease
Dr. Gobardhan Thapa
Resident, MD RD
NAMS Bir hospital

2. Presentation outline
• Relevant anatomy of coronary arteries.
• Common coronary artery anomalies.
• MDCT techniques.
• Role of MDCT for Common coronary artery
pathologies.

3. Coronary artery anatomy
• The coronary arteries - course through the epicardial
fat to supply the myocardium with oxygenated blood.
• Variability in the anatomy of the coronary arteries from
person to person, and the size and branching pattern of
each coronary artery can vary significantly.
• Imperative to distinguish benign variants from
congenital abnormalities that can lead to a
compromise of blood flow with subsequent myocardial
ischemia, infarction, or sudden cardiac death.

4. • Sinuses of Valsalva, three
anatomic outpouchings in the
ascending aorta.
• No coronary artery arises
from the noncoronary sinus,
the left main coronary artery
and right coronary artery
arise from the left and right
sinuses, respectively.
R
L
N
Fig. Normal coronary ostial anatomy.
Transverse image through the aortic
sinus from a coronary CTA shows the
left (L), right (R), and noncoronary (N)
sinuses.

5. Left Main Coronary Artery
• Vessel with the largest diameter
compared to the other coronary
arteries - variable length (average
length nearly 1 cm).
• In most patients, the left main
coronary artery bifurcates into two
vessels, the left anterior descending
coronary artery (LAD) and left
circumflex coronary artery (LCx).
• In ~20% to 30% of the patients the
left main coronary artery will
trifurcate, with a ramus intermedius
branch arising between the LAD and
LCx
Fig. Coronary CTA shows the left main
coronary artery (white arrowhead)
arises from the left sinus of Valsalva (L).
The left main bifurcates into the LAD
(white arrow) and LCx (black arrow).

6. Left Anterior Descending
Coronary Artery
• Courses over the anterior surface of
the left ventricle (LV) in the anterior
interventricular sulcus
• The diameter and length of the LAD
can vary significantly and can
terminate prior to reaching the LV
apex, terminate at the LV apex, or
wrap around the LV apex to supply the
inferior wall at the apical level.
• Divided into three portions:
– proximal LAD - portion of the LAD from
its origin to the ostium of the first large
septal branch or diagonal branch,
whichever arises first.
– mid-LAD - end of the proximal LAD to
half the distance to the LV apex.
– distal LAD - end of the mid-LAD to the
termination of the LAD.

7. • Gives septal branches
and diagonal branches
that are important in
supplying oxygenated
blood to the
anteroseptal and
anterolateral portions of
the LV myocardium,
respectively
Fig. coronary CTA shows the left main coronary artery
(black arrowhead) arising from the left sinus of
Valsalva (L). The left main bifurcates into the LAD
(white arrowhead) and LCx (not shown in plane). The
lateral branches of the LAD are diagonal vessels
(white arrow) that supply the anterolateral aspect of
the LV. The smaller septal arteries (black arrows)
supply the anteroseptal portion of the LV.

8. Left Circumflex Coronary Artery
• Courses posterolaterally between the LV and left atrium.
• Gives obtuse marginal (OM) vessels - oxygenated blood to
the inferolateral aspect of the LV.
• In inferolateral aspect of the left atrioventricular (AV) groove
and begins to wrap around the inferior aspect of the LV, it is
usually a diminutive vessel.
Fig. Volume-rendered image from a coronary CTA looking at the lateral aspect of the LV shows the left main
coronary artery trifurcating into the LAD (white arrow), ramus intermedius (white arrowheads), and LCx (black
arrows). The LCx courses in the groove between the left atrium and ventricle and gives rise to obtuse marginal
braches (black arrowheads) that supply the inferolateral aspect of the LV.

9. Ramus Intermedius/Intermediate
branch
• vary in size and distribution;
• in some patients it will course
anterolaterally to supply the
anterolateral portions of the
LV (similar to diagonal
branches),
• whereas in other cases it will
course inferolaterally to supply
the inferolateral portion of the
LV (similar to OM branches).
Fig. The left main (black arrowhead)
trifurcates into the LAD (white arrow),
LCx (black arrow), and ramus
intermedius branches (white star).

10. Right Coronary Artery
• Large vessel that courses anteriorly in the
right AV groove.
• Divided into three territories:
– proximal RCA - ostium of the RCA to half the
distance to the acute margin of the heart.
– mid-RCA - end of the proximal RCA to the acute
margin of the heart, and
– distal RCA - end of the mid-RCA to the origin of
the posterior descending artery.
• (acute) marginal arteries vary in size and
number.
• In right dominant patients, the distal RCA will
divide into two branches along the
undersurface of the heart - the posterior
descending artery (PDA) and posterior lateral
branch (PLB).
Fig. Right coronary artery (RCA)
anatomy. C-view of RCA from a
coronary CTA shows its division
into three territories.

11. Posterior Descending Artery
• ~75% to 88% cases: arises from the RCA >> right
dominant
• ~9% cases: arises from the LCx >> left dominant.
• In a smaller percentage of patients the PDA will
arise from the RCA, and a large PLB branch will
arise from the LCx; >> balanced or codominant.
• PDA is a mirror image of the LAD: While the LAD
courses in the anterior interventricular sulcus,
the PDA courses in the posterior interventricular
sulcus along the inferior aspect of the LV.
• Similar to the LAD the PDA gives rise to septal
branches that supply the inferolateral aspect of
the LV septum.
• The PDA is of variable size and length. In
patients with a smaller LAD the PDA tends to be
a larger artery and vice versa
Fig. Variable size of the posterior
descending coronary artery (PDA).
Two-chamber view from a coronary
CTA shows a large PDA (black arrows)
extending to the left ventricular apex.
The LAD (white arrows) is a smaller
vessel that ends proximal to the apex.

12. Posterior Lateral Branch
• courses laterally and extends along the
posterior AV groove between the inferior
aspect of the left atrium and LV.
• variable size and length but usually provides
oxygenated blood to the inferolateral base of
the LV.

13. Conus Branch
• Usually the first branch of the
RCA; can have a separate origin
from the right coronary sinus in
17% to 50% of patients.
• extends anteriorly to supply
blood to the right ventricular
outflow tract (RVOT) or conus.
• In some instances the conus
acts as a collateral pathway for
blood flow to the LAD, and this
circuit is often referred to as
the arterial circle of Vieussens.
Fig. conus artery. Axial oblique image from
a coronary CTA shows the conus branch
(white arrows), which is usually the first
vessel to arise from the right coronary
artery unless it arises directly from the
right aortic sinus. The vessel courses
superiorly and anteriorly to supply the
right ventricular outflow tract (RVOT).

14. Sinoatrial Nodal Branch
• Small vessel - often originates
from the RCA
• Arises from the LCx in about one
third of patients; Less commonly
the SA branch can arise from the
left main coronary artery, both the
RCA and LCx, or directly from the
aorta.
• courses posteriorly (RCA origin) or
medially (LCx origin) and
terminates in the region of the SA
node, which is located along the
posterior aspect of where the
superior vena cava enters the right
atrium.
Fig. SA nodal branch anatomy. Axial oblique
MIP image from a coronary CTA shows the
SA branch (arrows) arising from the proximal
right coronary artery (RCA) and coursing
posteriorly to end between left atrium (LA)
superior vena cava (SVC) just near its point
of draining into the right atrium.

15. Atrioventricular Nodal Branch
• Mostly arises from the very distal U-shaped aspect of the
distal RCA as is courses superior to the PDA.
• Small vessel that courses superiorly toward the posterior
anulus of the mitral valve

16. CORONARY ARTERY ANOMALIES
• Incidence: 0.5% and 1.5%.
• Frequently encountered on cardiac
computed tomography (CT).
• often clinically silent and are
frequently an incidental finding.
• Cause of sudden cardiac death in 5%
to 35% of young people.
• Best visualized with
electrocardiographically (ECG)-gated
CT angiography (CTA), the improved
temporal resolution of modern
scanners often allows for basic
assessment of coronary anatomy
even on nongated thoracic CT scans.
•Abnormalities of origin
•Abnormalities of course
•Abnormalities of
termination.

17. Abnormalities in Origin
Anomalies of Origin, Benign
Absence of left main coronary artery.
• ~0.4% to 2% of the population.
• LAD and LCx have independent origins from
the left sinus of Valsalva.
Anomalous origin of coronary arteries
within the aortic root near the proper
aortic sinus.
• Arise in a slightly eccentric location, although
with the correct sinus. For instance a
coronary may arise more laterally in the
sinus (near one of the valvular
commissures), slightly superiorly (near the
sinotubular junction), or slightly inferiorly
(closer to the valve).
Fig. Absent left main coronary artery

18. Anomalous origin of coronary arteries outside the
aortic root
• Arise from a location outside the sinuses – mostly
benign variants. For instance, one of the coronary
arteries may have a high origin 1 cm or greater above
the sinotubular junction and may be seen arising from
the ascending aorta or even the aortic arch.
• In extremely rare instances, a coronary artery - from
one of the arch vessels (right brachiocephalic, carotid,
or subclavian arteries), internal mammary artery, or
even the descending thoracic aorta.

19. Fig. High origin of the RCA. Anterior volume-rendered
image of the aorta and coronary ostia shows the RCA
arising from the ascending aorta (white arrow), well above
the sinotubular junction (white arrowhead).

20. Origin from anomalous sinus, benign
Retroaortic
• anomalous coronary artery - from
the opposite sinus and courses
posteriorly and extends between the
aorta and left atrium.
• commonly seen with the LCx arising
from the right sinus of Valsalva,
although it can arise directly from
the proximal RCA.
Anterior to pulmonary outflow tract
(prepulmonic or precardiac)
• anomalous coronary artery courses
anterior to the RVOT; mostly
involves the LAD or left main
coronary artery, which often arises
directly from the proximal RCA in the
setting of a single coronary artery.
Fig. Retroaortic course. Coronal oblique image
from a coronary CTA through the aortic root
shows the LCx (black arrows) arising from the
right coronary cusp and coursing posteriorly
between the aortic root and atria.
Fig. Prepulmonic course. Axial oblique image from a
coronary CTA shows LAD (black arrows) arising from
the right sinus of Valsalva (R) and coursing anteriorly
around the right ventricular outflow tract (RVOT)

21. Septal (intramyocardial) course
• usually involves the LAD arising
from the right coronary sinus.
• dives into the proximal aspect of
the LV septum - needs to be
distinguished from the interarterial,
potentially malignant course where
the anomalous coronary extends
medially between the two outflow
tracts.
Noncoronary sinus
• from the noncoronary sinus -
extremely rare anomaly.
• can occur with the RCA or left main.
Fig. Septal course of the LAD. Sagittal
oblique MIP image from a coronary
CTA in a patient with a single right
coronary artery (arrowhead) shows
the LAD coursing inferiorly and
medially (black arrows) before diving
into the interventricular septum.

22. Anomalies of Origin, Possibly
Malignant
Interarterial course
• coronary artery arises from the opposite coronary sinus
and courses medially between the two outflow tracts.
This can involve the RCA, left main, or LAD.
• Especially when involving the left main or LAD, can lead
to myocardial ischemia, infarction, and sudden cardiac
death.
• The ostium of the interarterial vessel may be narrowed
and is often referred to as slitlike. The proximal vessel
can also have a tangential course that leads to
proximal kinking of the vessel.

23. Fig. Axial oblique (A) and sagittal oblique (B) images from a coronary CTA show the RCA
(black arrows), which arises above the left coronary sinus, coursing between the aorta
and pulmonary artery (PA).
Fig. A, Axial oblique image from a coronary CTA shows the left main (black arrow) coursing
between the aorta and pulmonary artery. B, Sagittal oblique image through the proximal left
main shows severe narrowing of the vessel (white arrow) as it courses between the aorta and
pulmonary artery.

24. Anomalous origin of left main coronary
artery from pulmonary artery (ALCAPA).
ALCAPA, or Bland-White-Garland syndrome
• Rare congenital anomaly (1 in 300,000 live
births).
• When pulmonary artery pressures decrease in
the first few months of life, and if adequate
collaterals do not develop, poor flow from the
pulmonary artery to the left main coronary
artery leads to myocardial ischemia, infarct,
and cardiac death in 90% of infants in the first
year of life.
• may be asymptomatically discovered in their
eighth decade of life, ventricular arrhythmia
and sudden death is still common in this
population.
Fig. A, Axial oblique image from
a CTA shows the left main
coronary artery (black arrow)
arising from the pulmonary
artery (PA).

25. Single coronary artery
• Mostly, a single RCA, although a single left coronary
artery can occur
• In the setting of a single coronary artery, various
anomalous courses can be present, including both
benign (retroaortic, prepulmonic, septal,
wraparound) and potentially malignant (interarterial)
courses.

26. Abnormalities in Course
Myocardial Bridging
• common incidental finding (up to 58% of
patients undergoing coronary CTA)
• most often involves the mid-LAD, where a
band of myocardial tissue extends around
the vessel
• While the vessel is compressed during
systole, this rarely leads to symptoms,
because the coronary arteries fill during
diastole.
• Increased incidence of coronary artery
atherosclerotic disease proximal to the
bridge
• Deep bridges are more likely to be
symptomatic.
Fig. Axial oblique image from a
coronary CTA shows the mid-LAD
diving into the left ventricular
myocardium (white arrows),
consistent with a myocardial bridge.

27. Split (Double) Coronary Artery:
• extremely rare anomaly - one coronary artery arising from the sinus of Valsalva,
which then divides in its proximal portion into two parallel coronary arteries that
mirror their course; most commonly involves the RCA
• Since in most cases there is a single ostia, many have preferred to use the term split
to describe this anomaly. In rarer instances there is a true “double” or duplicate
coronary artery where each has an independent origin from the aortic sinus, with
near parallel courses.
• In general this is a benign anomaly.
Fig. Split RCA in a 23-year-old man. C-view of the right coronary artery
from a coronary CTA shows a single RCA proximally (white arrowhead);
the RCA splits into two parallel vessels (black and white arrows).

28. Abnormalities in Termination
Coronary Fistula
• may be acquired but are most often
congenital.
• Physiologically acts like a left-to-right
shunt (from the coronary sinus to the
pulmonary artery).
• Involved coronary artery is markedly
dilated and tortuous, and such a finding
on CT should lead to suspicion of a
fistula.
• Although a fistula can be an incidental
finding, patients may present with
congestive heart failure due to long-
standing shunt, ischemia due to a steal
phenomenon (preferential flow of blood
through lower-pressure fistula instead
of through higher-pressure capillary
bed), or endocarditis.
Fig. Coronary artery fistula. Curved
MPR image from a coronary CTA
shows a diffusely enlarged LCx
(white arrows) that drains into the
coronary sinus (CS), consistent with
a fistula.

29. CT TECHNIQUES
Patient Preparation
• Best images are obtained in the setting of a low heart rate, ideally below
65 bpm.
• Metoprolol (β-blocking agent) - commonly employed
– orally or IV. When used orally a 30-mg dose is often given 45 to 60 minutes before the
scan to ensure adequate absorption. For more rapid effect, IV metoprolol can be given a
few minutes before the scan. A 5-mg dose is typically administered and can be repeated
several times as needed.
• Verapamil (calcium channel blocker): alternative medication, - IV in 5-mg
doses. Other β-blocking agents are occasionally employed.
• To achieve coronary vasodilatation, nitroglycerin is typically used.
Sublingual tablet or tablets or as a spray moments before the scan is
initiated.

30. Contrast Injection
• Rapid injection of IV contrast - a large-bore catheter into a vein, ideally 18 gauge or
greater.
• Frontal and lateral low-energy scout images are first obtained to determine the
position of the heart.
• Bolus-tracking technique:
– a region of interest is placed in the aorta or left heart and sequential axial images are obtained.
– The coronary CTA is initiated when the density within the region of interest exceeds a designated
threshold value, usually set between 100 and 150 Hounsfield units (HU).
• Timing-bolus technique:
– a preliminary scan using a small quantity of contrast, usually 10 to 20 mL, is injected followed by
saline, and the transit time for the time for the contrast to peak (TTP) in the left circulation is
measured.
– After the TTP is determined, the timing of the diagnostic scan should be based on the TTP plus an
additional 4 to 5 seconds’ delay.

31. • The contrast injection for coronary CTA is typically
performed with 60 to 80 mL of a highly concentrated
iodine solution (300-400 mg/dL) at a flow rate of 5 to 6
mL/sec.
• For the latter part of the injection, iodine solution may
be diluted with saline to decrease attenuation in the
RV, which reduces artifact in the RCA system.
• A saline bolus is added at the end to facilitate transit of
the contrast bolus and eliminate artifacts in the highly
concentrated contrast in the superior vena cava.

32. CT Scanning Methods
• Minimum requirement for coronary CTA is a 64-
slice scanner- a number of scanners that meet or
exceed this threshold.
• Scanner configurations range from 64 to 320
slices, consist of 1- or 2-tube configurations (i.e.,
single or dual source)
• permit spatial resolution in the 0.5-mm range for
all 3 planes, and have temporal resolution as
rapid as 66 milliseconds.

33. • ECG gating to minimize or freeze coronary artery motion, and several gating
options exist
Retrospective ECG gating
Prospective ECG gating or triggering
Retrospective ECG gating:
• a volume of data is obtained throughout the cardiac cycle using a helical mode.
This technique produces the most complete set of images and permits assessment
of myocardial wall motion and function in addition to coronary artery evaluation.
• However, it also produces the highest radiation exposure.
• ECG-triggered dose modulation, which reduces tube output—and therefore
dose—at a designated noncritical point in the cardiac cycle, generally systole.

34. Fig. A, In retrospective ECG gating a helical scan is obtained as the current remains at
a constant level throughout acquisition. B, In retrospective ECG gating with dose
modulation a helical scan is obtained, but the tube output is decreased during the
noncritical parts of the cardiac cycle.

35. Prospective ECG gating or triggering :
• performed in an axial or helical manner. In the axial mode,
sequential scans are performed through the volume of interest
using a step-and-shoot technique at a prespecified point in the
cardiac cycle, usually mid- to late diastole. Tube output is turned off
for the remainder of the cardiac cycle, leading to dose reduction on
the order of 70% to 80% compared to standard retrospective ECG
gating.
• In prospective helical gating (high-pitched helical acquisition) an
entire volume is scanned within one heart beat, beginning at a
preselected time in the cardiac cycle.
• Major drawbacks of prospective ECG gating are the inability to
evaluate cardiac function (because scanning only occurs during a
limited part of the cardiac cycle) and difficulty with imaging at
higher heart rates (>65 bpm).

36. Fig. In prospective ECG gating (triggering) a
step-and-shoot axial scan is obtained, and the
tube is turned on during critical points in the
cardiac cycle, typically diastole.

37. Image Reconstruction and Post processing:
• typically reconstructed with slice thickness in
the range of 0.5 to 0.8 mm using a 50%
overlap.
• A field of view of 200 to 250 mm centered on
the heart is generally reconstructed.

38. Postprocessing of the image data
• multiplanar reformatted (MPR)
• maximum intensity projection (MIP)
• Volumetric images

39. Indications of coronary CT angiography
{American college of Radiology}
1. Detection of CAD with prior test results—Evaluation of chest
pain syndrome
2. Uninterpretable or equivocal stress test result (exercise,
perfusion, or stress echo)
3. Detection of CAD: symptomatic—Evaluation of chest pain
syndrome
4. Intermediate pretest probability of CAD, ECG
uninterpretable or unable to exercise
5. Detection of CAD: symptomatic—Acute chest pain
Intermediate pretest probability of CAD, no ECG changes,
and serial enzymes negative
6. Evaluation of coronary arteries in patients with new-onset
heart failure to assess etiology
7. Evaluation of suspected coronary anomalies

40. CORONARY ARTERY DISEASE
Coronary artery calcium scoring (CACS)
• well validated as a marker for cardiovascular risk, providing incremental value in
some instances over information obtained from the population-based Framingham
Risk Score (FRS).193 In particular, asymptomatic individuals with an intermediate
FRS (10%-20%) as well as diabetics are viewed as appropriate to undergo CACS to
assess the risk of coronary artery disease, according to the 2010 American College
of Cardiology Foundation (ACCF) guidelines.
• A weaker recommendation has been given for those with a low to intermediate
FRS (6%-10%). CACS is considered inappropriate in individuals at low risk (FRS >
6%).
• Higher CACS - greater likelihood of cardiovascular death, with the highest scores
associated with a relative risk of 10.8 as compared to individuals without coronary
calcium.
• The capability of CT to detect coronary artery calcification on CT was initially
described by Guthaner et al. in 1979 on EBCT, and this technique was shown to be
more sensitive than chest radiography or fluoroscopy.

41. • In 1990, Agatston et al described the first practical scoring system for CACS.
• Using 3-mm collimation EBCT, they defined as a calcified focus any pixel in the
coronary arteries with a threshold value of 130 HU or greater, using a minimum of
1-mm2 area to exclude noise artifact.
• further stratified scoring based on the density measurement above the threshold,
assigning a score of 1 for 130 to 199 HU, 2 for 200 to 299 HU, 3 for 300 to 399 HU,
and 4 for 400 HU or greater.
• The Agatston score is still widely used and is the sum of the score (1-4 above) on
each slice added together for each scan slice.
• In an effort to produce greater inter- and intrascan reproducibility, volume and
mass CACS measurements were introduced subsequently.However, these
approaches are less well validated than the Agatston score.
• Using the Agatston method, scores of 1 to 10 are considered to reflect minimal
coronary artery calcification, 11 to 100 mild, 101 to 400 moderate, and greater
than 400 severe calcification. An Agatston score of 400 or more indicates a strong
possibility of hemodynamically significant coronary artery stenosis
• With current use of MDCT, CACS is typically obtained with ECG prospective
triggering and a radiation exposure of approximately 1.5 mSv

42. • A zero calcium score also has important clinical
and prognostic value. Asymptomatic individuals
with absent calcium on CACS are unlikely to
develop a major adverse cardiac event.
• The association of a zero calcium score with a low
risk for cardiovascular events remained true even
in diabetic individuals. Increase in the calcium
score generally occurs over time, particularly in
patients with a non-zero initial score.

43. Coronary Stenosis
• Current capabilities of coronary CTA include anatomic
assessment, plaque characterization, CT perfusion, and
CT evaluation of fractional flow reserve (FFR).
• Advances in MDCT technology permit routine
evaluation of the coronary artery lumen.
• Evaluation of coronary stenosis is typically performed
on thin-section axial and MPR images.
• Axial and MPR images can be supplemented by MIP or
volume-rendered images.
• Plaque morphology and quantification can also be
assessed. Stenosis of 50% or greater is generally
considered significant

44. • 64-slice coronary CTA: sensitivity of 98%,
specificity of 89%in assessing coronary artery
stenosis compared with catheter angiography.
• MDCT - to evaluate acute chest pain in the
emergency department.
• Noninvasive imaging is useful for patients at
low to intermediate risk for acute ischemia.

45. • Coronary CTA for severe nonspecific chest
pain - so-called triple rule-out (TRO) study.
• TRO protocol - comprehensive ECG-gated
study through the entire thorax, enabling
enhancement of both left-and right-sided
circulations. Its main disadvantages as
compared with dedicated coronary CTA are a
higher radiation exposure and contrast dose.

46. Coronary Plaque
• Coronary CTA - comprehensive assessment of the
location, severity, and characteristics of coronary
atherosclerotic plaque.
• “vulnerable plaque” - a plaque at risk to cause an
acute coronary event.
• Pathologically these plaques typically have a lipid-rich
core, a thin fibrous cap, and loss of integrity of the
endothelium, with platelet aggregation.
• Vulnerable plaques are often clinically silent until the
fibrous cap ruptures and the necrotic core pours into
the vascular lumen, leading to a thrombogenic
reaction.

47. • This is because many vulnerable plaques tend to
undergo positive vascular remodeling, with
outward expansion of the vessel rather than
narrowing (negative vascular remodeling).
• Therefore it is critical to assess for imaging
findings of both coronary narrowing and
vulnerable plaque.
• Documented CT features of plaque associated
with acute coronary events include positive
vessel remodeling and low-attenuation
plaques(particularly, plaques <30 HU).

48. Fig. Multiplanar (A) and curved planar reformatted images (B) of the LAD
demonstrate small areas of calcified and noncalcified plaque (arrow).
Fig. Curved planar reformatted images of the right coronary (A) and LCx arteries (B)
demonstrate extensive calcified plaque interspersed with noncalcified plaque. C, Curved planar
reformatted image of the LAD demonstrates extensive mixed plaque and positive remodeling
(arrows).

49. • “napkin-ring sign” - indicative
of a thin-cap atheromatous
vulnerable plaque; visualized
as a rim of high attenuation,
representing the inflamed
fibrous cap, surrounding an
area of low attenuation,
representing the necrotic lipid
core.
• present in ~41% of those who
ultimately developed an acute
coronary event; an
independent predictor of the
acute coronary syndrome.
Fig. Napkin-ring sign. A, Cross-sectional view of
the middle segment of the right coronary
artery shows atherosclerotic plaque with a thin
rim of high attenuation (which represents the
inflamed fibrous cap) surrounding an area of
low attenuation (which represents the necrotic
lipid core). B, Longitudinal view of the same
plaque demonstrates stenosis with positive
vascular remodeling.

50. Miscellaneous Coronary Artery Diseases
Coronary artery aneurysm:
• a segment of the coronary artery that measures more than 1.5 times the
adjacent normal coronary artery.
• classified by involvement of all coronary layers (true vs. false) and
morphology (fusiform vs. saccular).
• Etiologies:
– atherosclerosis, Kawasaki’s disease and other vasculitides, inflammatory
disorders, connective tissue disease, infection, trauma, fistulas and anomalies,
and iatrogenic causes.
– In the developed world, atherosclerosis is the most common cause of
coronary artery aneurysms in adults, whereas Kawasaki’s disease is the most
common etiology in children.
• Coronary CTA accurately depicts the size and location of the aneurysm, as
well as internal characteristics such as thrombus and calcification.
• Diffuse narrowing of the coronary arteries with mural thickening may be
caused by coronary vasculitis.

51. CORONARY ARTERY BYPASS GRAFTS
• CABG has remained the definitive treatment for
advanced coronary artery disease.
• Patency of the coronary grafts is critical for long-term
survival and depends on the type of graft used.
• Internal mammary artery grafts typically remain
attached to their origin at the subclavian artery;
dissected from the parasternal region and are often
anastomosed to the LAD because of their higher
patency rate.
• Saphenous vein grafts - harvested from the legs and
attached as a free graft to the ascending aorta and
coronary artery distal to the site of obstruction.

52. • Traditional approach to diagnosis has been
catheter-based coronary angiography.
• MDCT - noninvasive alternative for
assessment of CABG patency.
• 64-slice or greater MDCT: improved
assessment of bypass grafts.
• Occluded grafts are readily detected, and
improvement in evaluation of CABG stenosis.

53. Fig. volumetrically reconstructed images showing patent left internal mammary
artery– to-LAD graft and saphenous vein–to–posterior descending artery graft.
Fig. Images in two patients showing a “ghost” sign (arrow in A) and a
“nubbin” sign (arrow in B), indicating occlusion of CABG.

54. CORONARY STENTS
• Metal coronary stents - to maintain coronary
artery; result in a larger residual diameter and
reduce the rate of in-stent restenosis to
approximately 30% as compared to coronary
angioplasty.
• Drug-eluting stents has permitted further
reduction in restenosis rates.

55. • Coronary CTA - to evaluate stent occlusion and in-stent
restenosis.
• Even with CT-scanning using 64 or more slices, there
are limitations in imaging coronary stents. With current
technology, studies demonstrate a high negative
predictive value (usually 90%-100%) for significant
stenosis and a rate of nonevaluable stents of 8%.
• Stents 3 mm or more in diameter are more likely to be
assessable.
• More recent technologic advances such as myocardial
perfusion and iterative reconstruction may lead to
improved stent visualization.

56. Fig. A 54-year-old man with coronary stent.
Curved planar (A) and multiplanar (B)
reformatted images of the RCA show a patent
stent in the proximal vessel (arrows).

58. References
• CT and MRI of the whole body, 6/e; John
Haaga.
• Cardiac Imaging, 3/e; Stephen W. Miller