Download Choose Between MRA and CTA

Frandcis P. Chan. MD, PhD: Choose between MRA
and CTA: a rational approach
May 13, 2008- 3:05 PM
CTA versus MRA – A Frequent Question
Choosing Between CTA and MRA,
a Rational Approach
Frandics Chan, M.D., Ph.D.
Stanford University
Medical Center
Lucile Packard
Children’
Children’s Hospital
CE-MRA
LPCH
SUMC
CE-CTA
Department of Radiology
Objectives
Considerations for Decision
• To learn the decision process for
choosing CT versus MRI for
cardiovascular imaging.
• To understand common capabilities
shared by CT and MRI.
• To understand individual strengths of
CT and MRI.
In decreasing order of importance
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LPCH
Department of Radiology
Contraindications
• CTA
– Anaphylactic reaction
– Renal failure
• Relative contraindications
– Mild allergic reaction
– Pregnancy
– Arrhythmia
1.
2.
3.
4.
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Contraindications
Required imaging capabilities
Relative risks
Established approaches
LPCH
Department of Radiology
Iodinated Contrast Use in Renal Failure
• MRA
– Pacemaker / AICD
– Stimulators
– Electronic prosthesis
– Infusion pumps
– Certain implants and
surgical clips
• Gadolinium Contrast
– Allergic reaction
– Pregnancy
– Renal failure
• Consider alternative test
• In mild renal insufficiency
– Isosmolar contrast agent
– Prehydration
– Bicarbonate
– Acetylcisteine (Mycomyst)
– Post-procedure creatinine level
http://www.mrisafety.com/
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Department of Radiology
Stanford Radiology 10th Annual Multidetector CT
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Department of Radiology
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Frandcis P. Chan. MD, PhD: Choose between MRA
and CTA: a rational approach
Gadolinium Use in Renal Failure
• High dose gadolinium contrast is
nephrotoxic
– Not usually a problem at single dose for
MRI use.
– Should not be used as a substitute for
iodinated contrast in x-ray based imaging.
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SUMC
Department of Radiology
May 13, 2008- 3:05 PM
Gadolinium Use in Renal Failure
• Associated with the development of
nephrogenic systemic fibrosis (NSF)
– Rare disorder recognized since 1997
– ~250 cases reported
– Painful skin induration in extremities,
loss of skin elasticity, contracture
– Associated with gadolinium contrast use
– Risk to pediatric patients is unknown
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Current Recommendation
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Department of Radiology
Non-Contrast MRA
• For patients with creatinine clearance
< 30 mL/min
– Avoid gadolinium use if possible
– Consider non-contrast MR angiography
– For patients on dialysis, dialyze after
gadolinium use as soon as possible.
Navigator
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SUMC
Department of Radiology
Considerations for Decision
SUMC
• 3D-Angiography
MRA
LPCH
Department of Radiology
Stanford Radiology 10th Annual Multidetector CT
Symposium
– MRI:
• Lower resolution
(0.7x1.5x2.0mm)
• High contrast
• No bone
• More metal artifact
Contraindications
Required imaging capabilities
Relative risks
Established approaches
– CT
• High resolution
(0.3x0.3x0.7mm)
• Bone
• Less metal artifact
CTA
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Department of Radiology
Shared Imaging Capabilities
In decreasing order of importance
1.
2.
3.
4.
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Department of Radiology
2
Frandcis P. Chan. MD, PhD: Choose between MRA
and CTA: a rational approach
May 13, 2008- 3:05 PM
Shared Imaging Capability
Distinct Imaging Capabilities
• MRI cine
MRI
• MRI
– High temporal resolution
(40 ms)
– Less motion artifacts
– Flow quantification
• CT cine
– Low temporal resolution
(>100 ms)
– More motion artifacts
Cardiac Outputs (Phase Aligned)
16000
14000
Flow (cc/min)
12000
10000
8000
6000
4000
2000
0
-2000 0
Gated CTA
10
15
20
Cardiac Phase
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Department of Radiology
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Distinct Imaging Capabilities
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Department of Radiology
Distinct Imaging Capabilities
• MRI
• MRI
– Flow quantification
– Perfusion imaging
– Myocardial scar
– Flow quantification
– Perfusion imaging
– Myocardial scar
• CT
– Lungs
– Airways
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SUMC
Department of Radiology
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Considerations for Decision
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Relative Risks
• MRI
In decreasing order of importance
– Prolonged exam
– Difficult access
MRI
1.
2.
3.
4.
Department of Radiology
Contraindications
Required imaging capabilities
Relative risks
Established approaches
CT
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LPCH
Department of Radiology
Stanford Radiology 10th Annual Multidetector CT
Symposium
SUMC
LPCH
Department of Radiology
3
Frandcis P. Chan. MD, PhD: Choose between MRA
and CTA: a rational approach
May 13, 2008- 3:05 PM
Relative Risks
Relative Risks
• MRI
• Background
radiation: 3 mSv/yr
• CXR: 0.1 mSv
• Chest CT: 3-5 mSv
• CTA: 5-10 mSv
• Gated CTA: 10-20 mSv
• Cath: >10 mSv
– Prolonged exam
– Difficult access
– Radiation
• Repeated examinations favor MRI
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SUMC
• Critically ill patients favor CT
• CT
Department of Radiology
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Considerations for Decision
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Established Approaches
• MRI
In decreasing order of importance
1.
2.
3.
4.
SUMC
– Aorta
Contraindications
Required imaging capabilities
Relative risks
Established approaches
LPCH
Department of Radiology
SUMC
Established Approaches
LPCH
• MRI
– Aorta
– Systemic Veins
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Department of Radiology
Established Approaches
• MRI
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Department of Radiology
Department of Radiology
Stanford Radiology 10th Annual Multidetector CT
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– Aorta
– Systemic Veins
– TOF c Function
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Department of Radiology
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Frandcis P. Chan. MD, PhD: Choose between MRA
and CTA: a rational approach
May 13, 2008- 3:05 PM
Established Approaches
Established Approaches
• MRI
• MRI
– Aorta
– Systemic Veins
– TOF c Function
Aberrant RCA
• CTA
• CTA
– Pulm. Embolism
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LPCH
– Aorta
– Systemic veins
– TOF c function
Department of Radiology
– Pulm. Embolism
– Coronary arteries
(young children)
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LPCH
Department of Radiology
SUMC
LPCH
Department of Radiology
Guidelines
•
•
•
•
•
•
•
•
First determine contraindications
Function and flow studies go to MRI
Lung and airway studies go to CT
Repeated studies go to MRI
Critically ill patients go to CT
Aortic and caval imaging favor MRI
Pulmonary arteries and veins favor CT
Coronary arteries in young children favor CT
SUMC
LPCH
Department of Radiology
Stanford Radiology 10th Annual Multidetector CT
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