Clinical%20application%20of%20MR%20perfusion%20

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Clinical application of MR perfusion MSK
oncology

• Tips and Tricks
• Pedro Teixeira MD, PhD

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Introduction

• Limits of conventional MRI on MSK oncology
• Potential applications of MR perfusion
• Difficulties for clinical application
• - Complex acquisition protocols
• - Data post processing
• - Interpretation and
  reproducibility

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The bases

• How does perfusion imaging works?
• Perfusion imaging methods
• - Ultrasound
• - CT
• - MRI

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Sequence choice

• Contrast enhanced
• Gradient Echo
• K space filling

• Partial K space filling
• Good temporal and spatial résolution
• Angiography-like images
• Visual analysis

• Full K space filling
• Low spatial resolution
• Optimal quantitative analysis (permeability)

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4D MR angiography - bases

• Time Resolved MRA sequences (TRICKS, TWIST)

• K space is divided in 4 concentric zones A, B, C,
  D
• Zone A (Image contrast) is read more frequently
• An initial full acquisition (zones A, B, C and D)
  is used as a subtraction mask

D C B A

temps


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A B C D
A
B
C
D
A
B
A
C
A
D
A
B
A
masque
Masque
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Sequence choice
TRICKS
FSPGR

• Visual and semi-quantitative parameters Partial
  filling
• Quantitative parameters Full k space filling

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Protocol FAQ

• Which injection delay and rate should be used?
• How much contrast do we need?
• What is the acceptable temporal resolution range?
• What is the optimal acquisition length?

?
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Data analysis
Types of perfusion parameters available
Visual
Semi-quantitative
Quantitative
Research
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Visual Parameters

• Enhancement intensity
• Enhancement speed
• Néovaisseux

Adjacent artery as standard of reference!
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Semi-quantitative parameters

• Slope
• Maximal enhancement
• Enhancement integral
• Time-to-peak
• Arterial-tumoral peak delay

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Enhancement curve morphology
Type I
Type II
Type III
Type V
Type IV
van Rijswijk et al.
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Data analysis

• Data comparison
• Which standard of reference?
• Temporal parameters
• - Arterial input as the standard of
  reference

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Linterprétation

• Intensity related parameters
• - normalization

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Clinical applications

• Limited role for tumor characterization
• Can aide in the identification and follow-up of
  tumors with a known perfusion behavior
• Post operative evaluation (fibrosis vs
  recurrent/residual tumor)
• Additional criterion for adjuvant therapy
  response
• Pre biopsy planning

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26 year-old female with a dedifferentiated
sarcoma of the thoracic wall treated surgically.
Contrôle post opératoire
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54 year-old woman with a distal femur
ostéosarcome treated with chemotherapy. Treatment
response assessment.
Pre-treatment
Post-treatment (3 cycles)
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Pre-treatment
Post-treatment (3 cycles)
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Biopsy guidance
T2 FS
T1
T1 GD FS
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TRICKS MIP
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Take home messages

• MR perfusion is clinically available
• It can help in the characterization and follow-up
  of MSK tumors
• Optimize the acquisition protocol to the intended
  clinical use
• Beware of inappropriate data comparisons

Thank you for your attention! Ped_gt_at_hotmail.com