MRA of the Abdomen and Extremities

MR Angiography
Vascular Imaging of the Body and Extremities
Phillip Young MD
Assistant Professor
of Radiology
Mayo Clinic
Rochester, MN
USA
North American Society of Cardiovascular Imaging 2011
Baltimore, Maryland
Disclosures
• I have no financial or commercial
interests relevant to this presentation
to disclose
• CE-MRA is off-label use of
gadolinium*
Acknowledgements:
K-space movies from:
•Kiaran McGee PhD
Mayo Clinic Rochester
•Brian Hargreaves PhD Stanford University
Contrast Enhanced MRA
• Patient preparation
• Protocol design
• Coverage and Resolution
• K-space and Injection Rate
• Time-resolved MRA
• Noncontrast MRA and other New
Techniques
Patient Preparation
• Communicate
requirements to
patient
• Choose injection site
before IV is placed
• Upper
extremities/ chest
• Inject
contralateral to
site of interest
Popliteal entrapment syndrome
• 30 year old with
remote
Kawasaki
Disease
• Palpable
aneurysm in
right brachial
artery
• Stenosis of the
subclavian artery
related to Kawasaki
disease?
Second Phase
First Phase
[
]
T2*
Protocols: Coverage and
Resolution
• Trade-offs:
• Spatial resolution
• Anatomic coverage
• SNR
• Scan time
• CTA sets a high standard of
resolution
Coverage and Resolution
• Some presets have resolution of
256x160
• I prefer 512x192 or 384x224
• I avoid parallel imaging if possible
• Noise introduced
• Potential artifacts
Para-Aortic Soft Tissue Mass
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
High Resolution Allows
Multiplanar Reformatting
Aortic Aneurysm Evaluation
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
MRA
Low-Dose Time-resolved MRA
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
21
K-space and Injection Rate
• Most scanners allow you to choose
the manner in which k-space is
acquired
• This should be matched with an
appropriate injection rate and scan
time
K-space and Injection Rate
K-space and Injection Rate
• Generally, you
would like the peak
contrast
concentration at the
center of k-space
• Still need
contrast for the
periphery
K-space and Injection Rate
• Different readout options available
• Sequential
• Elliptic Centric
• Injection rate is important
Sequential
K-space
• Best choice when:
• Imaging all vessels in
large FOV
• >30 sec scan time
• Timing is difficult
• No power injector
QuickTime
H.264 decom
are needed to see
Sequential
Scan Duration
Slow Injection
Rate
K-space
QuickTime
H.264 decom
are needed to see
Wide Plateau
Time
Start scan: Peak time - Scan time + Contrast Volume
2
2 x Flow Rate
First Phase
Second Phase
K-space and Injection Rate
• Different readout options available
• Sequential
• Elliptic Centric
• Injection rate is important
Elliptic Centric
• When executed well, provides best
contrast
• Can give a “snapshot” of flow at a
given time
• Requires very accurate timing
• Rapid injection rate
Elliptic Centric
Scan Duration
K-space
Fast Injection
Rate
Time
Start scan: Peak time + Contrast Volume
2 x Flow Rate
Sequential
Elliptic Centric
Aortitis?
No
Time-Resolved MRA
• View-sharing techniques
• TRICKS, TWIST, TREAT
• Newer Techniques
• CAPR
Time-Resolved MRA
• Useful when timing
is difficult (at least
1 phase will be
right)
• Lower legs
• Hands
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
• AVM or dynamic
information
AVM of the Forearm in Parkes-Weber Syndrome
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Open vessel?
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
CTA MIP
Second vessel
Is filling from below ankle
MRA MIP
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
43
Conclusion
• Many opportunities to tailor MRA
technique to the needs of your
patients
• Recent and coming developments in
MRA show even more promise for the
future of MR vascular imaging