Download 2:30pm: CT and MR in Coronary Artery Imaging

CT & MRI OF THE
CORONARY ARTERIES –
TIPS AND TRICKS
Dr. Karen Lyons, MB BCh BAO
Pediatric Radiologist, Arkansas Children’s Hospital
Assistant Professor, University of Arkansas Medical Sciences
INTRODUCTION
•  Why does CT and MR imaging of coronary arteries matter
•  Reasons to do it in children
•  Technical pitfalls of each modality
•  Case examples
INDICATIONS FOR
CORONARY IMAGING
•  Coronary vasculitis
•  Kawasaki disease
•  Anomalous coronary origins
•  ALCAPA
•  AAOCA
•  Coronary fistula
•  Pre-operative evaluation in CHD
CORONARY CTA VS. MRA
MRA
•  Better temporal
resolution
•  Feasible during free
breathing
•  Non contrast
•  Allows concomitant
evaluation of function,
perfusion, viability
CTA
•  Better spatial resolution
•  Images less degraded by
valves, or metallic coils
•  Inferior temporal
resolution
•  Dependence on slower
heart rates
CORONARY MRA VS. CTA
4-year-old with common coronary from right
cusp, inter-arterial course of left coronary
3D SSFP Navigator
19-day-old with myocardial infarction,
single coronary arising from RVOT
Volumetric axial, retrospective ECG-gated,
ED 11.7 mSv
CARDIAC CT… NEED FOR SPEED
•  Ability to image dependent on HR and CT temporalcoverage
•  Solutions: faster gantry rotation, dual x-ray tube
sources, broader detector array, combining multiple
heart beats, and partial scan and undersampled
acquisition and reconstruction
•  Temporal resolution < 80 ms and coverage > 40 cm/s
feasible
CT ANGIOGRAPHY - MERITS
• 
• 
• 
• 
• 
Spatial resolution slightly better than MRI.
Gold standard for non-invasive coronary imaging
3D–dataset with true isotropic resolution
Multi-phasic and functional studies possible
Good temporal resolution – about .35-2 seconds per
dynamic, but less than MRI
•  Half scan reconstruction 175 ms
•  Safe and effective in presence of metallic coils,
pacemaker wires, valvular prostheses, aneurysm clips
CT ANGIOGRAPHY - PITFALLS
•  Ionizing radiation
•  Dependent on fast injection rates to dilate the coronary
arteries
•  Timing is critical
•  Fast HRs in small children – systole may be the best phase
•  If HR >65bpm or variable, temporal resolution 175ms not fast
enough
•  Multiple prospectively gated heart beat scans using
multisegment reconstruction or multiple heart beat scans
using retrospective gating.
7 YEAR OLD BOY WITH
CHEST PAIN
HR: 90 bpm
Pitch 0.293
3mL/sec
70mL total injection
HLHS S/P NORWOOD &
COILING OF AORTIC OUTFLOW
MR CORONARY ANGIOGRAPHY
MR CORONARY ANGIOGRAPHYMERITS
•  No ionizing radiation
•  Calcification
•  Non contrast
•  High temporal resolution
MR CORONARY ANGIOGRAPHY PITFALLS
•  Lower spatial resolution
•  Longer imaging time
•  Diaphragmatic drift
•  PPM/ ICD
•  Susceptibility artifact
MR CORONARY ANGIOGRAPHY –
TECHNICAL CONSIDERATIONS
•  Coil selection (5 vs 32 channel)
•  Field strength (3T vs 1.5T)
•  Target volume vs. whole heart technique
•  Contrast agent
Cardiac Localization
Right Coronary Artery (RCA)
1
2
3
4
x
x
x
x
x
x
1. 
2. 
3. 
4. 
Acquire a stack of 2D axial localizers from a coronal localizer.
Use 3-point tool (red x) to create slab orientation along RCA from base to apex.
Again Use 3-point tool to fine tune the location of the slab.
Resulting images should lay out RCA in-plane.
Cardiac Localization
Left Anterior Descending Artery (LAD)
1
2
3
4
x
x
x
1. 
2. 
3. 
4. 
Acquire a stack of 2D coronal localizers through aortic root.
Position axial oblique slab along LAD from its origin toward the apex.
Use 3-point tool to identify the origin and distal points along the LAD.
Resulting images should lay out LAD in-plane.
PERFUSION/ VIABILITY
IMAGING
•  Perfusion imaging: 3T MR provides improved contrast in
first-pass myocardial perfusion imaging over a range of
gadolinium doses
•  Viability imaging: Improved real-time cine LGE imaging
method at 3T
•  Specialized techniques:
•  Stress perfusion MRI imaging
•  MR evaluation of allograft coronary vasculopathy
EXAMPLES
CASE 1
•  2 y/o female with unknown heart disease, lost to follow-up
•  At 8 presented with syncope, echo/angio/ecg showed mitral
insufficiency, pulmonary arterial hypertension, A-Fib à mitral
annuloplasty performed
CASE HISTORY
•  2 y/o female with unknown heart disease, lost to follow-up
•  At 8 presented with syncope, echo/angio/ecg showed mitral insufficiency,
pulmonary arterial hypertension, A-Fib à mitral annuloplasty performed
•  At 10, again had syncope with episodic SOB… had further work-up
including cardiac cath and cardiac MRI à showed dilated LA, mitral
insufficiency, LVH, restrictive cardiomyopathy, PAH, dysrhythmia…
•  Eventually came to TCH for Cardiac CTA
CARDIAC CTA
Texas Children’s Hospital
Singleton Department of Pediatric Radiology
CARDIAC CTA
OUTSIDE CARDIAC MRI
ANOMALOUS ORIGIN OF THE LEFT
CORONARY ARTERY FROM THE
PULMONARY ARTERY (ALPACA)
•  Bland-White-Garland syndrome
•  1 / 300,000 live births
•  0.25 – 0.5% of all congenital heart defects
ALCAPA
•  “Coronary steal” phenomenon à left-to-right shunt = abnormal left
ventricular perfusion
•  Myocardial ischemia and infarction
ALCAPA
•  “Coronary steal” phenomenon à left-to-right shunt = abnormal left
ventricular perfusion
•  Myocardial ischemia and infarction
•  Infant type: 90%, present in first year of life with heart failure (usually
within weeks/months of birth), if untreated results in death
ALCAPA
•  “Coronary steal” phenomenon à left-to-right shunt = abnormal left ventricular
perfusion
•  Myocardial ischemia and infarction
•  Infant type: 90%, present in first year of life with heart failure (usually within
weeks/months of birth), if untreated results in death
•  Adult type: development of significant collateral circulation, but usually not
enough à chronic LV subendocardial ischemia, mitral insufficiency, malignant
ventricular dysrhythmias à sudden cardiac death in 80-90% (small %
asymptomatic)
ALCAPA
FACTORS ENABLING SURVIVAL
BEYOND INFANCY
IMAGING FINDINGS
•  LCA arising from MPA, typically left inferolateral aspect
•  MR: retrograde flow on SSFP cine images
•  Secondary findings:
• 
• 
• 
• 
Dilated/tortuous RCA and LCA
Dilated intercoronary collaterals (epicardial and interventricular)
Left ventricular hypertrophy and dilation from chronic myocardial ischemia
Myxomatous degeneration and ischemia of papillary muscles, causing mitral
insufficiency/prolapse
•  Global hypokinesis
•  Dilated bronchial arteries acting as systemic collaterals
•  Delayed subendocardial enhancement à predictive of malignant dysrhythmias and
indication for repair
DILATED CORONARY ARTERIES
•  Kawasaki disease
•  Multiple focal coronary artery aneurysms
•  Young patients following viral illness
•  Coronary artery-coronary sinus fistula
•  Only fistulous artery is dilated
•  Takayasu Arteritis
•  Coronary artery aneurysms and stenosis
•  Additional involvement of aorta and great vessels
TREATMENT
•  Infant type:
•  Coronary button transfer: Direct reimplantation with button
of MPA (preferred)
•  Takeuchi procedure: transpulmonary baffle
•  Adults:
•  CABG with ALCAPA ligation
•  Heart transplantation if severe left ventricular
dysfunction
CASE 1
•  4 yo female with abnormal EKG
CMRI
ALCAPA
•  Anomalous left coronary artery arising from the PA, rare and
90% diagnosed in 1st year of life, Bland-White-Garland
syndrome
•  Problem is coronary steal when pulmonary perfusion pressure
falls after first couple of months, risk of myocardial ischemia
•  Late presentation usually with LV dysfunction, myocardial
infarction
ALCAPA
•  Surgical repair:
•  direct re-implantation (also known as coronary button transfer
technique),
•  Tackeuchi repair (where the pulmonary artery is opened,
creating an anterior transverse flap of native pulmonary artery
tissue, which creates a baffle to carry the aortic oxygenated
blood to the anomalous coronary artery ,
•  left coronary artery ligation
•  coronary artery bypass grafting (CABG)
ALCAPA
•  Complications;
•  Narrowing of the anastomoses
•  Myocardial ischemia
CASE 2
•  7 y.o. male with fever, strawberry tongue, mouth hyperemia
and conjunctivitis
Texas Children’s Hospital
Singleton Department of Diagnostic Imaging
CHEST CTA
Axial
CHEST CTA
CHEST CTA
DIFFERENTIAL DIAGNOSIS
•  Kawasaki disease
•  Other vasculitides
•  Coronary fistulae
KAWASAKI DISEASE
•  Rare, unknown etiology – abnormal response to infection/
toxin suggested
•  Small to medium vessels
•  Young children, M>>F, peaks: 6-24 months, after 5 years,
most self-limited
•  Prolonged fever, conjunctivitis, inflamed tongue/oral mucosal
membranes, cervical LAD, maculoerythematous rash hands/
feet
KAWASAKI DISEASE
•  Myocarditis (36%), pericarditis (16%)
•  Fusiform/saccular coronary aneurysms (2nd-3rd wk), occlusion/
stenosis, calcifications
•  ASA (high dose then low dose), IVIG (acute – may decrease
coronary abnormalities), tPA, ocasionally bypass or transplant
CASE 3
•  10 year old with abnormal ECHO
10 YEAR OLD WITH
ABNORMAL ECHO
ANOMALOUS AORTIC ORIGIN OF A
CORONARY ARTERY (AAOCA)
• 
• 
• 
• 
0.6% incidence ARCA
0.1% incidence ALCA
14-17% SCD
10-30 yoa
• 
• 
• 
• 
Mechanism unclear
Intra-arterial
Intra-mural
Ostial stenosis
IMAGING OF AAOCA
• 
• 
• 
• 
• 
CT preferred to MRI
Improved spatial resolution and contrast
Evaluate ostium and proximal course
Retrospective CT gives dynamic information
CT
• 
• 
• 
• 
Coronary dimension
Pericoronary fat
Morphology of ostium
Good surgical correlation in 25 pts
STANDARDIZED NOMENCLATURE
MANAGEMENT
REFERENCES
•  Sakuma H. Coronary CT versus MR angiography: The role of MR angiography.
Radiology 2011;258:340-349
•  Sena L, Krishnamurthy R, Chung T. Pediatric Cardiac CT. En Lucaya J. Strife J,
eds. Pediatric Chest Imaging. Berlin, Heidelberg: Springer-Verlag;
2007:361-395
•  Araoz PA et al: 3 Tesla MR Imaging provides improved contrast in first-pass
myocardial perfusion imaging over a range of gadolinium doses. J Cardiovasc
Magn Reson. 2005;7(3):559-64
•  Kadbi Met al: An improved real-time late gadolinium enhancement imaging
method at 3T. Conf Proc IEEE Eng Med Biol Soc. 2011;2011:531-4
REFERENCES
•  Hussain T., Fenton M., Peel S.A., et al; Detection and grading of coronary
allograft vasculopathy in children with contrast-enhanced magnetic resonance
imaging of the coronary vessel wall. Circ Cardiovasc Imaging. 2013;6:91-98
•  Noel C, Molossi S, Krishnamurthy R, Moffett B, Krishnamurthy R. Cardiac MR
stress perfusion with regadenoson and dobutamine in children: single center
experience in repaired and unrepaired congenital and acquired heart disease. J
Am Coll Cardiol. 2016;67(13_S):964.
•  Dietz SM, Tacke CE, Kuipers IM, et al. Cardiovascular imaging in children and
adults following Kawasaki disease. Insights into Imaging. 2015;6(6):697-705.
doi:10.1007/s13244-015-0422-0
•  Mery C, Lawrence S, Krishnamurthy R, Sexson-Tejtel K, Carberry K, McKenzie
D, Fraser C. Anomalous Aortic Origin of a Coronary Artery: Toward a
Standardized Approach. Semin Thorac Cardiovasc Surg. 2014;26(2):110-22