Clinical Perfusion Imaging 1'5 3T

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Clinical Perfusion Imaging1.5 3T

• Lawrence N. Tanenbaum, M.D. FACR
• New Jersey Neuroscience Institute - Seton Hall
  University
• JFK Medical Center-Edison Imaging
• www.drtmasters.com drt_at_drtmasters.com
• Edison, New Jersey

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Perfusion imagingprinciples

• monitor the first pass of a rapid bolus injection
  of a standard MRI contrast agent through the
  cerebral vasculature
• Gd T2 susceptibility effects cause a transient
  signal loss proportional to the amount of tracer
  in a given region
• integration of data over the time course of the
  first pass of the contrast agent allows creation
  of map of brain perfusion

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perfusion
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Perfusion imagingtechnique

• initiate single-shot EPI series
• power inject Gd at 0.1-0.2 mmol/kg at 3 cc/sec.
• process data on operators console
• technologist creates map of whole brain dynamic
  susceptibility contrast

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SE PerfusionEchoSpeed
SLE

• 1900/ 80, 1 shot SE EPI
• 192 x128
• 11 locations
• 7-10 mm / 0 mm
• 107
• 30 x 0.65 FOV (19), f R-L
• 35 phases
• 3 cc/sec, 8 sec inject delay

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SE PerfusionEchoSpeed Plus

• 1835-2000/ 80, 1 shot SE EPI
• 192 x128
• 11-12 locations
• 7-10 mm / 0 mm
• 105 111
• 30 x 0.65 FOV (19), f R-L
• 35 phases
• 3 cc/sec, 8 sec inject delay

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GE Perfusion EchoSpeed

• single shot gradient echo EPI
• TR 2266 TE 24.2 60 FA
• 7-10 mm / 0 mm
• FOV 22
• 128 x 128
• 35 phases, 12 locs, 80 seconds
• 3 cc/sec, 8 sec inject delay

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GE PerfusionEchoSpeed Plus

• single shot gradient echo EPI
• TR 1749 TE 19.5 (NVi 19.2)
• 60 FA
• 7-10 mm / 0 mm
• FOV 22
• 128 x 128
• 35 phases, 12 locs, 63 seconds
• 3 cc/sec, 8 sec inject delay

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GRE PerfusionTwinSpeed

• single shot gradient echo EPI
• TE Twin 18.2, NVi 19.2
• EchoSpeed 19.5, ES 24.2
• TR 2000, 60 FA
• 7-10 mm / 0 mm
• FOV 22
• 128 x 128
• 33 phases, 15 locs, 66 seconds
• 3 cc/sec, 8 sec inject delay

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GRE Perfusion3T channel

• single shot gradient echo EPI
• TE Twin 18.2
• TR 2000, 60 FA
• 7 / 0 mm
• FOV 22
• 96 x 128
• 33 phases, 18 locs, 68 seconds
• 3 cc/sec, 8 sec inject delay

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Perfusion imagingtechnique

• SE technique
• less susceptibility artifact
• capillary level assessment
• GE technique
• faster
• higher contrast resolution
• susceptibility proportional to TE

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EchoSpeed Plus
EchoSpeed
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radiation
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Perfusion imagingindications

• neoplasm
• characterization and surveillance
• stroke / ischemia
• Neuropsychology/ Psychiatry
• cardiac stress

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Perfusion Imaging
tumor vs. radiation necrosis
Conventional T2
CBV

• status post surgery and RT for glioblastoma
• conventional MR exhibits non-specific T2 changes
• CBV map indicates small region of recurrent tumor

recurrent tumor
UCSF
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Perfusion imaging

• BBBB studies are insufficient to distinguish
  tumor recurrence from radiation related changes
• FDG PET
• 81 sensitivity, 40 specificity
• Kahn et al AJR 1994 1631459-1465
• Perfusion MR
• 78 sensitivity, specificity
• Lev et al RSNA 1997.

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PET-CT
radiation necrosis
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CBF
CBV
cCBV
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MR-PET fusion
radiation necrosis
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Steamboat 2001
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perfusion
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new onset seizures
Steamboat 2001
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Glioblastoma multiforme
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Multi-voxel MRSI
256 voxels 5 minutes
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Perfusion imagingneuro-oncology

• primary CNS lesions have vasculature that may
  have intact tight junctions
• low grade tumors may not enhance on BBBB studies
• extent of enhancement correlates poorly with the
  extent of high grade tumors
• DSC studies sensitive to abnormal capillary
  density
• perfusion imaging may significantly outperform
  BBBB studies in delineating the presence and
  extent of primary brain tumors

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M. Sage, M.D.
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3T
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Perfusion imagingneuro-oncology

• critical adjunct to BBBB imaging of neoplasms
• many tumors have high rCBV
• regions of increased rCBV correlate with areas of
  active tumor.
• heterogeneous patterns of perfusion suggest high
  grade
• radiation necrosis typically demonstrates low
  rCBV
• lesion characterization may be possible
• meningiomas have very high CBV in contrast to
  schwannomas

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SE perfusion 3.0T
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meningioma
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0.0375 mmol/kg gadobenate
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hemangioblastoma
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Pilocytic astrocytoma
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Perfusion imaginggoals in neuro-oncology

• refine characterization, diagnosis
• biopsy site selection
• routine tumor surveillance
• radiation necrosis vs. recurrent tumor
• primary vs. metastatic

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Perfusion imagingfindings in ischemia

• CBV
• regional perfusion deficit
• compensatory increased volume
• MTE (MTT)
• regional prolongation of transit time

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Perfusion MRI
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Perfusion imaging
Mean Time to Enhance (MTE, MTT)
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Perfusion imagingischemia

• changes seen almost immediately after the
  induction of ischemia
• more sensitive than conventional MRI
• perfusion findings often more extensive than
  those on DW-EPI in early stroke
• more accurately reflects the amount of tissue
  under ischemic conditions in the hyperacute
  period than DW EPI
• DSC DWEPI (Na imaging) tissue at risk

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CBV
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Diffusion-Perfusion imagingBrain Attack Exam
T2
Diffusion Weighted
DSC
Region of low cerebral blood volume correlates
with ischemic region
Ischemic region appears bright on DW Image
10 hrs after onset of symptoms
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Brain Attack Exam
CBV
FLAIR vs. Diffusion reveals acute infarct
MTE
Diffusion vs. DSC reveals tissue-at-risk
St. Lukes Hospital, Milwaukee, WI, Breger et al.
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CT Perfusionimaging technique

• identify slice/ slices covering three vascular
  territories
• inject 40 cc _at_4 cc/sec.
• 370-400 agent concentration
• 45 second scan, 5 sec prep delay
• 80 kVp, 190 mAs
• process data on scanner console or workstation

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CT Perfusion
MTT
CBF
CBV
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ICA occlusion
CBV / NEI
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ICA occlusion
Mean transit time / MTE
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ICA occlusion
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post diamox
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seizure vs. right hemispheric infarction
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right hemispheric ischemia
Las Vegas 2000
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CT Perfusion- r/o stroke
CBF
CBV
MTT
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CT Perfusion- r/o stroke
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Perfusion CT functional assessment

• right ICA, MCA, ACA occlusion
• left ICA stenosis
• left M1 stenosis
• right A2 fills via left A2
• VB system normal

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Perfusion imagingcerebrovascular reserve

• ability to augment flow to vascular beds
  compromised by vascular stenosis
• acetazolamide (Diamox) or 5 CO2 challenge
• abnormal results correlate with an increased risk
  of stroke
• perfusion MR/CT may obtain info analogous to that
  of SPECT, transcranial doppler

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Mean transit time
difference
before Diamox
after Diamox
T. Lee London, Ontario
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Cerebral blood flow (rCBF)
before Diamox
after Diamox
difference
T. Lee London, Ontario
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Cerebral blood volume (rCBV)
after Diamox
difference
before Diamox
T. Lee London, Ontario
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HxTIA US carotid stenosis
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Functional imagingAlzheimers disease

• FDG PET
• marked temporo-parietal hypometabolism
• Tc-HMPAO SPECT
• marked temporo-parietal hypoperfusion
• DSC MRI
• correlates well with SPECT

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DAT
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Dementia DAT
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Perfusion imagingdementia

• findings correlate well with cognitive impairment
• may be useful in monitoring patients genetically
  at risk, and monitoring the effect of therapy

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Perfusion imaging

• Traumatic brain injury
• focal rCBV deficits that correlate with cognitive
  impairment
• Schizophrenia
• decreased frontal lobe rCBV
• HIV/ AIDS
• multiple discrete foci of decreased CBV
• Polysubstance abuse
• multiple discrete foci of decreased CBV

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traumatic brain injury
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traumatic brain injury
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DSC MRI
Tc HMPAO SPECT
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Cerebral perfusion imagingtechnique comparison

• Gd-perfusion MR (DSC)
• rCBV, MTE
• Tc-HMPAO SPECT, Xe-CT
• cerebral blood flow (rCBF)
• Iodine-perfusion CT
• rCBF, rCBV, MTT
• FDG-PET
• cerebral metabolism

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Perfusion imaging

• advantages over PET, SPECT
• no radiotracer necessary
• higher spatial resolution

Steamboat 2001
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Perfusion imaging

• advantages over PET, SPECT
• cost efficiency
• added cost of about 45
• free if already injecting
  for BBBB
• SPECT 1000, PET 2000

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Perfusion imaging

• advantages over PET, SPECT
• no radiotracer necessary
• higher spatial resolution
• cost efficiency
• speed
• DSC study in about one minute
• less motion artifact in uncooperative patients
• processing and filming in about 5 minutes

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Time resolved breast MR
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VIBRANT ASSET 1 min/pass bilat breast fat
sat auto-subtracted
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FSPGR
T1 FLAIR
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Myocardial perfusion

• first pass perfusion
• 100 msec per image
• Adenosine stress
• 7 sec ½ life
• 5 cc/sec power injection
• 0.05 mmol/kg

stress
rest
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Myocardial perfusion FastCard echo train

• hybrid of FGRE and EPI
• first pass perfusion
• 100 msec per image
• speed
• reduced artifacts

stress
rest
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REST
STRESS
S. Wolff, MD
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stress
Cardiac perfusion
rest
S. Wolf MD
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stress
rest
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stress
inferolateral ischemia
rest
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Myocardial viability
La Jolla 2001

• Wall thickness / motion
• akinesis / dyskinesis
• EDWT lt 3 mm
• Dobutamine stress
• low dose viability
• high dose coronary arteries
• Hyperenhancement

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Delayed hyperenhancement

• mechanism
• contrast passes through injured cell membrane
• hyperenhancement due to higher combined signal of
  enhanced intracellular and extracellular spaces
• mde technique
• T1 prep FGRE scan 10-15 minutes after
  administration of 0.1 0.2 mmol/kg of contrast.
• significance
• 90 of patients with HE of 51-75 of wall
  thickness involved did not improve after
  revascularization

Kim et al NEJM 20003431445-53
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Delayed hyperenhancement

• 804 segments with abnormal contractility
• 694 with some hyperenhancement (HE)
• likelihood of improved contractility decreased as
  transmural extent of HE increased
• improvement seen in
• 256/329 (78) without HE
• 109/183 (60) with 1-25 wall thickness involved
• 46/110 (42) with 26-50 wall thickness involved
• 13/124 (10) with 51-75 wall thickness involved
• 1/58 (2) with gt75 wall thickness involved

Kim et al NEJM 20003431445-53
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Delayed hyperenhancement
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JFK Medical Center