ACRSPR MR Imaging of Congenital and Pediatric Cardiovascular MR Disorders

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ACR-SPR MR Imaging of Congenital and Pediatric
Cardiovascular MR Disorders
October 9-11, 2009

• Individual workstations for all attendees
• Leading vendor cardiovascular MR post-processing
  software at every workstation
• Emphasis on computer-based self-paced learning
  with significant one-to-one faculty-to-attendee
  interaction

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Pediatric Cardiovascular MR Techniques
Cynthia K. Rigsby, MD Department of
Medical Imaging Childrens Memorial Hospital
Chicago, IL
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Disclosure

• The use of gadolinium for MRA and for power
  injection is considered off-label
• The use of gadolinium for children under the age
  of 2 years is considered off-label

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Pediatric Cardiovascular MR Techniques

• Case examples

• Structure
• Function
• Flow
• Tissue Composition

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Structure

• White blood techniques
• 2D and 3D steady state free precession
• Gradient echo
• Black blood techniques
• Inversion recovery fast spin echo/ HASTE
• MRA
• High resolution
• ECG-gated
• Time-resolved

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White BloodSteady State Free Precession

• Balanced FFP, FIESTA, True FISP
• High contrast to noise ratio
• Low TE values
• Lessen turbulent flow artifacts

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White BloodGradient Echo
Gradient echo
SSFP

• Accentuate turbulent flow jets
• Higher TE values than SSFP

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White BloodGradient Echo
Local shim
No local shim

• Severe banding/off-resonance artifacts on SSFP
  imaging

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White BloodGradient Echo

• Infants/small children if TR for SSFP imaging gtgt
  4 ms

3 month old with DORV s/p
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Structure

• 3D steady state free precession
• Whole heart coverage
• Cardiac and extracardiac vascular imaging
• No contrast
• Isotropic, high resolution
• Up to 1 mm in plane resolution
• Coronary anatomy
• Performed free breathing
• Relatively operator independent
• Ideal for imaging children and CHD

Fenchel M, Greil GF, Martirosian P, Kramer U,
Schick F, Claussen CD, Sieverding L, Miller S.
Three-dimensional morphological magnetic
resonance imaging in infants and children with
congenital heart disease. Pediatr Radiol. 2006
Dec36(12)1265-72. Epub 2006 Sep 28.
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Adult lost to follow up and no available records.
Short of breath. Echo (poor windows) showed
CC-TGV and LV (subpulmonary) to PA conduit.
Evaluate anatomy and function.
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3D SSFP
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3D SSFP

• Mesocardia
• Azygous continuation of the IVC
• Hepatic veins drain directly to the RA
• Pulmonary veins drain to the left atrium
• Atrioventricular discordance ventriculoarterial
  discordance
• L-looped ventricles, L-TGV (CC-TGV)
• LV (subpulmonary) to distal main PA conduit
• Artifact related to metal in conduit
• Mild enlargement and hypertrophy of the systemic
  RV
• Small native PA. Normal RPA and LPA.
• Aortic insufficiency
• Right aortic arch with mirror image branching
• Right and left coronaries arise beneath the
  sternum from separate ostia from the right
  anterior facing sinus
• Liver in the LUQ spleens in the RUQ

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3D SSFP Limitations

• Non-cine images only. No functional info.
• Supplement with cine SSFP and flow sequences
• Future time resolved 3D SSFP

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Black Blood

• Characterize myocardial structure and composition
  
• Double inversion recovery fast spin echo/HASTE
• T1 SE
• May be performed with fat suppression and/or post
  contrast

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Black Blood

• 7 yo male chest pain, vomiting, heart rate of 250
  bpm
• Echo large mass

Double inversion recovery fast spin echo/HASTE
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Black Blood

• MRI and biopsy c/w fibroma

Double inversion recovery FSE fat suppression
post gad
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3D-Magnetic Resonance Angiography

• Mainstay for extracardiac vascular anatomy
• Gadolinium contrast
• Acquire multiple phases with each injection
• /- Timing of image acquisition
• Nephrogenic systemic fibrosis
• Images improved with breath holding

Roya S. Saleh, Swati Patel, Margaret H. Lee, M.
Ines Boechat, Osman Ratib, Carla R. Saraiva, and
J. Paul Finn Contrast-enhanced MR Angiography of
the Chest and Abdomen with Use of Controlled
Apnea in Children Radiology 2007 243 837-846.
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High Resolution MRA

• MRA traditionally been performed without
  ECG-gating
• Images can be limited by motion at the base of
  the heart
• Aortic root
• Ascending aorta

16 year old with Marfan syndrome
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High Resolution MRA

• MRA traditionally been performed without
  ECG-gating
• Images can be limited by motion at the base of
  the heart
• Aortic root
• Ascending aorta

16 year old with Marfan syndrome
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ECG-gated MRA

• Acquisition synchronized with ECG tracing
• Images acquired during cardiac phase with least
  motion
• Possible because of parallel imaging and reduced
  acquisition times
• Helps to eliminate motion at the base of the
  heart
• More reliable assessment of aortic root and
  ascending aorta

Groves, Elliott M., Bireley, William, Dill,
Karin, Carroll, Timothy J., Carr, James C.
Quantitative Analysis of ECG-Gated
High-Resolution Contrast-Enhanced MR Angiography
of the Thoracic Aorta. Am. J. Roentgenol. 2007
188 522-528
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ECG-gated MRATeen with probable coarctation
Case courtesy of James Carr, Northwestern
University
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Time-Resolved MRA

• Repeated quick acquisition of 3-D MRA datasets
• 700 ms 6-10 seconds per phase
• Temporal information can be useful for diagnosis
• Tradeoff between temporal and spatial resolution
• Eliminates need for timing of contrast arrival
• Inject and scan
• Less susceptible to breathing and motion
  artifacts
• TRICKS, subsecond MRA

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Time-Resolved MRA
2.5 sec temporal resolution
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Time-Resolved MRA 10 yo with dyspnea on exertion
1 second temporal resolution
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Function

• SSFP imaging
• Myocardial tagging

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Function

• Systolic function
• How well the heart contracts during systole to
  force blood out of the ventricles
• RV and LV systolic function assessed with
  ejection fractions
• Endocardial border tracings on systolic and
  diastolic images
• 16 yo female TOF s/p repair

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Function
When/if to intervene Tetralogy of Fallot
patients? Therrien, etal. Optimal timing for
pulmonary valve repair in adults after TOF
repair. Am J Cardiol 2005 95 779-82.

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Probability of major adverse clinical outcomes
-death, sustained VT, functional
deterioration-late (median 21 years) after TOF
repairmedian follow-up 4.2 years

• Taken from Knauth, A L et al. Heart
  200894211-216
• Z- score of 7 172 ml/m2 women
• 185 ml/m2 men

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Function

• Diastolic function
• How well the heart relaxes
• Diastolic dysfunction
• Limitation in ventricular relaxation causing
  impairment of ventricular filling during diastole
• Can precede systolic dysfunction
• More difficult than systolic function to directly
  measure

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Function
14 yo with hypertrophic cardiomyopathy
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Function

• Myocardial tagging can be used to assess systolic
  and diastolic function
• Parallel RF pulses saturate tissue and lead to
  tags
• Qualitative analysis
• Subjective and not reproducible over time

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Function

• Quantitative analysis
• Marks location of muscle tags and follows over
  the cardiac cycle
• Accurately index wall motion abnormalities
• Myocardial strain

Mid-LV inferior wall circumferential strain
Taken from Ennis DB, Epstein FH, Kellman P,
Fananapazir L, McVeigh ER, Arai AE. Assessment
of regional systolic and diastolic dysfunction
in familial hypertrophic cardiomyopathy using MR
tagging. Magn Reson Med. 2003 Sep50(3)638-42.
Jérôme Garot, David A. Bluemke, Nael F. Osman,
Carlos E. Rochitte, Elliot R. McVeigh, Elias A.
Zerhouni, Jerry L. Prince, and João A. C. Lima
Fast Determination of Regional Myocardial Strain
Fields From Tagged Cardiac Images Using Harmonic
Phase MRI Circulation 2000. 101 981-988

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MR Phase Contrast Imaging

• Direct non-invasive measurement of
• blood flow velocity, direction, and flow rate
• Valve stenosis and regurgitation
• Shunt fractions (QpQs)
• Relative lung blood flow
• Diastolic dysfunction
• Myocardial wall motion
• Non-contrast MRA
• Significance of vascular stenoses
• Assessment of collateral flow

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Phase Contrast Imaging

• Pulmonary valve regurgitation
• Image perpendicular to vessel of interest
• Adequate temporal and spatial resolution
• Accurate velocity and blood flow measurements
• 16 yo TOF s/p repair

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Phase Contrast Imaging

• Flow direction
• White
• Black
• Gray
• Velocity
• Flow volume
• Velocity
• Vessel area

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Phase Contrast Imaging

• Regurgitant fraction
• Backward flow/forward flow
• 34/56 ml/beat
• 60 regurgitant fraction

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Phase Contrast Imaging
Therrien J, Provost Y, Merchant N, Williams W,
Colman J, Webb G. Optimal Timing of Pulmonary
Valve Replacement in Adults after TOF Repair.
American Journal of Cardiology 2005 95 779-782.
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Tissue Composition

• T2
• Myocardial delayed enhancement
• Perfusion

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T2

• Iron overload states
• ßthalassemia/Sickle cell disease/Hemochromatosis
• Iron accumulation in organs including heart and
  liver
• Chelation therapy to remove excess iron
• May or may not be completely successful
• Cardiac complications due to iron overload are
  leading cause of death in thalassemia
• Cardiac failure directly correlates with cardiac
  iron burden

Wood JC, Enriquez C, Ghugre N, et al. Physiology
and pathophysiology of iron cardiomyopathy in
thalassemia. Ann N Y Acad Sci. 2005 1054
386-395.
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T2 Principles

• T2 is an MRI signal decay rate
• Greater iron in magnetic field increases field
  inhomogeneity and shortens T2
• T2 values correlate with heart and liver iron
  load
• T2 imaging replacing liver biopsy and used to
  direct chelation therapy

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T2

• Gradient echo pulse sequence with multiple TE
  values
• Mono-exponential decay curve fit to the MRI data
• Slope 1000/T2
• Higher iron content will have steeper curve and
  lower T2

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T2
Normal volunteer T2 30 ms
Thalassemia patient T2 3 ms
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T2
Normal volunteer T2 33 ms LIC 1.04 mg/g dry
weight liver
Thalassemia patient T2 2.1 ms LIC 12.5 mg/g
dry weight liver
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Tissue CompositionMyocardial Delayed Enhancement

• Gadolinium rapidly equilibrates between
  extracellular space and interstitium
• Washes in and washes out of normal myocardium
• Slower wash in and wash out from damaged
  myocardium
• Delayed enhancement
• Images performed 15 minutes following contrast
• Scar or myocardial replacement fibrosis

Raymond J. Kim, David S. Fieno, Todd B. Parrish,
Kathleen Harris, Enn-Ling Chen, Orlando
Simonetti, Jeffrey Bundy, J. Paul Finn, Francis
J. Klocke, and Robert M. Judd Relationship of MRI
Delayed Contrast Enhancement to Irreversible
Injury, Infarct Age, and Contractile Function
Circulation 100 1992-2002
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Myocardial Delayed Enhancement
15 yo s/p left ventriculotomy as an infant for
apical muscular VSD repair. Chest pain during
sports.
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Myocardial Delayed Enhancement

• Hypertrophic cardiomyopathy
• Patchy MDE in area of hypertrophy
• Indicative of replacement fibrosis
• MDE associated with markers for risk of sudden
  cardiac death and progressive disease

Moon etal. Toward Clinical Risk Assessment of HCM
with Gadolinium CMR. JACC 200341 1561-7.
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Myocardial Delayed Enhancement

• Thrombus imaging
• Failed classic Fontan patients prior to Fontan
  conversion surgery
• Retrospective review
• No false negative MRI studies for thrombus
  compared with surgical findings

CT and MRI Imaging of the Failed Fontan
Circulation prior to Fontan Conversion. Ladino
M, de Freitas RA, Michelotti M, Deal BJ,
Mavroudis C, Backer C, and Rigsby CK. 93rd RSNA
Scientific Assembly and Annual Meeting, Chicago,
Illinois 2007.
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Myocardial Delayed Enhancement

• 3 year old with chest pain, abnormal ECG, and
  elevated cardiac enzymes
• Delayed enhancement
• Myocarditis
• May be nodular, subepicardial
• Does not respect vascular territories
• Cath negative biopsy c/w myocarditis

Lim etal. Non ischemic causes of delayed
myocardial hyperenhancement on MRI. AJR 2007
188 1675-1681
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Perfusion ImagingFirst Pass Contrast Enhancement
18 month old with 5 days of fever WBC 174K, 80
eosinophils
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Myocardial Delayed Enhancement

• Idiopathic hypereosinophilic syndrome
• Eosinophil mediated organ damage
• Thrombus
• Inflammation/fibrosis
• Restrictive cardiomyopathy (late)

Paydar A, Ordovas K, Reddy G. MRI for
Endomyocardial Fibrosis. Pediatr Cardiol.DOI
10.10007
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Pediatric Cardiovascular MR Techniqueshttp//www.
childrensmemorial.org/cynthia-rigsby-rsna-presenta
tion.ppt

• Structure
• 2D and 3D imaging
• SSFP, Gradient echo, MRA
• Function
• SSFP and myocardial tagging
• Flow
• Phase contrast imaging
• Tissue Composition
• T2, delayed enhancement, perfusion imaging

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