neuroimaging_1.mri evaluation of brain tumors a review of functional neuroimaging techniques_by dr....
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MRI evaluation of brain tumors- a review of functional neuroimaging techniques in
clinical practice
Dr. Henry KF MAK
Clinical Assistant Professor &Associate Director of 3T MRI Imaging Unit, University of
Hong KongClinical Instructor, Diagnostic Neuroradiology, University of
Virginia Medical Center,USA
StructuralFunctional
Molecular
MRI
MR Spectroscopy
MRI Functional Neuroimaging Tools for brain tumors
– Diffusion Weighted & Tensor Imaging
– Perfusion/Permeability Imaging
– MR Spectroscopy
– Susceptibility-weighted Imaging
– Functional MRI
Pathologic – Radiologic Correlation
Pathology RadiologyCellularity T2/FLAIR SI,
DWI & ADC
Infiltration T2/FLAIR SI, DTI
Endothelial proliferation and Vascularity
Enhancement, Perfusion and Permeability Imaging
Metabolic Activity MRS
Necrosis Ring Lesion, MRS, DWI & ADC
Hemorrhage T1 and T2 SI, SWI
Cellularity in brain tumorsDiffusion Weighted Imaging
Apparent Diffusion Coefficient imaging
• Diffusion of water spins - isotropic • Based on molecular diffusion first described by
Einstein in 1905: Brownian motion
H2O molecule displacement is completely random and Is limited only by the boundaries of the container
Hagmann P, Radiographics 2006.
Low grade →high grade gliomas
Postoperative Diffusion Abnormality
Pre-op Immed post-op
DWI ADC
2-month F/U 4-month F/U
Recurrence?
Anti-VEGF in recurrent GBM
ADC- Tumor cellularity, tumor ischemia, extracellular matrix
Mak HKF et al., Cancer Imaging, 2012
T2W Post Gd
Ktrans DWI ADC
Tumor Infiltration
Diffusion Tensor Imaging
Isotropic diffusion Anisotropic diffusion
Random Directionality
DWI vs DTI
3T DTI with Parallel Imaging
centrumsemiovale
superiorlongitudinal
fasciculus
cingulum bundle
corpuscallosum,
body
55-directions, b=1000 s/mm2, with ASSET (R=2)
1.8 mm isotropic spatial resolution
DTI - Loss of Anisotropy
DTI and Tumor ImagingT2
From: J. Burdette and Neeraj Chepuri, WFU
MRI ScanHi-Res. Anatomical Scans
DTI Scan (15 minutes)DTI Map Processing
(~10 minutes)
DTI Fiber Tracking(~30 minutes)
Stereotactic Surgical NavigationAnatomical Images Integrated with DTI Fiber Tracks
Presurgical Image Processing
Courtesy of Jeffrey I. Berman, PhD (UCSF)
shoulder
wrist
Roland Henry PhD, Jeff Berman, PhD (Radiology), Mitch Berger, MD (Neurosurgery)
DTI Fiber Tracking of Motor Fibers Launched from Intra-Operative Cortical Stimulation Seed Points
Endothelial Proliferation and Vascularity
Perfusion Imaging
*blood flow per unit time through thecapillary bed of a tissue
Unit: Milliliter / 100 gram Tissue / Minute
Perfusion*
Dynamic Susceptibility T2*W(DSC) Perfusion MR Imaging
• What it is NOT Absolute measure of tissue
perfusion• What it IS Relative measure of tissue
volume, Rough estimation of
intravascular GD-DTPA• What it CAN BE Surrogate marker of
angiogenesis Predictor of outcome Potential endpoint of
angiogenesis treatment
baseline bolus
recirculation
T2*-weighted susceptibility signal time curve
ab
b x 100a
T2* signal intensity time curve
0
100
200
300
400
500
600
700
800
900
1000
0 10 20 30 40 50 60
Time
Sig
nal I
nten
sity
0
200
400
600
800
1000
1200
1400
1600
0 10 20 30 40 50 60
Time
Sig
nal I
nten
sity
Lung carcinoma metastasis
Grade IV glioma (glioblastoma multiforme)
Lung carcinoma metastasis
Grade IV glioma
(glioblastoma multiforme)
Met Glioma
Glioma vs. Solitary Metastasis
MetsGlioma
Glioma vs. Metastasis: Peritumoral rCBV
0.39
2.34
0.79
1.11
Mets
Glioma
Law M et al. Radiology 2002
Metabolic Activity
MR Spectroscopy
Proton Magnetic Resonance Spectroscopy (1H-MRS)
1H-MRS Metabolites @ 1.5 Tesla
Shift (ppm)
Biologic correlate Surrogate marker
NAA 2.01 Neuronal marker (density & function)
↓↓Tumor proliferation↓Edema
Cr 3.03 Energy buffer & shuttle
↓Tumorproliferation
Cho 3.19 Membrane turnover
↑↑Tumor proliferation
Lac 1.31 Anaerobic metabolism
↑Hypoxia; radioresistance
Lip 0.9-1.2 Necrosis ↑Rapid tissue destruction
Examples of 1H-MRS (TE=136ms) of different brain tumours.
Howe et al. Magn Reson Med 2003
Special Property of Lactate
Inverted
Recurrent tumour versus radiation necrosis
1H-MRS (TE=288ms) in a GBM patient in the splenium of the corpus callosum before and after superselective intra-arterial cerebral infusion of bevacizumab, showing reduction of Cho/NAA ratio posttreatment.
Jeon et al. AJNR 2012
Proton MR Spectroscopy (1H MRS)
Lipid/Lactate
NAACho
Cr
Choline
Normal
Brandao 2013 Magn Reson Imaging Clinics N Am
Citrate at 2.6ppm is significantly more prominent in aggressive pediatric astrocytoma
Bluml et al. Neuro-Oncology 2011
FunctionChange in
tumourN-acetyl-aspartate
(NAA)Neuronal marker ↓
Creatine (Cr) Cerebral metabolism marker ↓
Choline (Cho) Reflect membrane synthesis and degradation ↑
Myo-inositol (mI) Glial marker ↑Lactate (Lac) Sign of impaired energy
metabolism ↑Citrate Intermediate in
tricarboxylic acid cycle, malignant process marker
↑
NecrosisADCCBVMRS
Tumor necrosis versus PUS
GBM Abscess
T2W
DWIADC
Post Gd
Necrotic tumor (cerebral metastasis)
Mills SJ et al., Cancer Imaging, 2012
T2 Post-contrast T1 rCBV
Delayed Radiation Necrosis
3-month follow up
Radiation Necrosis
Tumor
Hemorrhage Susceptibility Weighted Imaging
Susceptibility Weighted Imaging
• SWI is a fully velocity-compensated 3-D gradient-echo sequence.
• Consists of magnitude and phase images.
• Phase mask improves contrast by making low phase areas darker.
Sehgal et al., 2005
Functional MRI
Preoperative Brain Mapping
A right-handed patient with left temporal lobe tumor
speech functional activation just posterior to the tumour
Comparison of fMRI and intra-operative cortical stimulation for speech function mapping-A case study. XLZhu, Neursurgery Henry Mak, Neuroradiology
Tumour腫瘤
Speech areas
Corticospinal tract皮層脊髓束
Neuronavigation plan- preoperative術前神经导航計劃
Paper marks speech areas over the cortex
Sylvian fissure
The navigation pointer is pointing at The speech area mapped out by cortical stimulation
Navigation (green cross) is exactly
over the fMRI speech area (pink circle)
Pathologic – Radiologic Correlation
Pathology RadiologyCellularity T2/FLAIR SI,
DWI & ADC
Infiltration T2/FLAIR SI, DTI
Endothelial proliferation and Vascularity
Enhancement, Perfusion and Permeability Imaging
Metabolic Activity MRS
Necrosis Ring Lesion, MRS, DWI & ADC
Hemorrhage T1 and T2 SI, SWI
Pathologic – Radiologic CorrelationPathology Radiology
Cellularity T2 SI, DWI & ADC
Endothelial proliferation and Vascularity
Enhancement, Perfusion and Permeability Imaging
Necrosis Ring Lesion, MRS, DWI & ADC
Hemorrhage T1 and T2 SI, SWI
Labeling Indices MRS, Th 201 and FDG
Infiltration T1 and T2 SI, DTI
Endothelial Proliferation and Vascularity
Permeability Imaging
T1W Dynamic contrast enhanced (DCE)
transK
epk
evpv
Cp(t)
Ce(t)
Sorensen AG, et al. Cancer Research 2009
MRI ScanHi-Res. Anatomical Scans
DTI Scan (15 minutes)DTI Map Processing
(~10 minutes)
DTI Fiber Tracking(~30 minutes)
Stereotactic Surgical NavigationAnatomical Images Integrated with DTI Fiber Tracks
Presurgical Image Processing
Courtesy of Jeffrey I. Berman, PhD (UCSF)
Preoperative DTI TractographyHigh-Grade Glioma: Stereotactic Examination
3D SPGR PostGad
T1
3D FSE T2
PyramidalTract
Postoperative MRIHigh-Grade Glioma: Day 2 Post-Op
PostGad T1
FLAIR
DTI Fiber Tractography: Brain ShiftN
imsk
y et
al.
Neu
rosu
rger
y (2
005)
8-15 mm of intra-op brain shift
DSC pMRI derived variables:
1.Relative cerebral blood volume (rCBV)
2.Abnormal recovery (aRec)
Color Overlay of rCBV Map
Glioblastoma multiforme
Low grade astrocytoma
Johnson G et al. Measuring blood volume and vascular transfer constant from dynamic T2*W contrast enhanced MRI. Magn Reson Med 2004; 51: 961-68.
Johnson G et al. Measuring blood volume and vascular transfer constant from dynamic T2*W contrast enhanced MRI. Magn Reson Med 2004; 51: 961-68.
Limitations
• Susceptibility Artifacts–Near brain-bone-air interface• Anterior & middle cranial fossa
–Metal, blood products, Ca++
6 mm
4 mm
T1 effect
Blood-Brain-Barrier Leakage
Nyquist ghost
Glioblastoma multiforme
Low- Grade Glioma
Recent Advances in MR Neuroimagingof Brain Tumors
Diffusion Imaging DWI- tumor necrosis vs pus - cellularity DTI- tumor infiltration, stereotactic surgery
Perfusion & Permeability Imaging rCBV- HGG vs LGG; HGG vs mets
(endothelial proliferation & vascularity) BBB permeability (ktrans) - HGG vs LGG rCBV/ ktrans - HGG vs post-irradiation
necrosis
Recent Advances in MR Neuroimagingof Brain Tumors
Recent Advances in MR Neuroimagingof Brain Tumors
MR Spectroscopy: high Cho, low NAA- tumor, but not specific (neuronal loss and membrane breakdown) high lactate/lipid- HGG vs LGG (anaerobic
metabolism & tumor necrosis) low Cho, low NAA- post-irradiation necrosis
(fibrinoid necrosis)
GBM with increased rCBV
Multiple Sclerosis plaque
GBM
What is MRS?
• MRS and MRI share the same physical principles
• MRS is a method which conveys the chemical composition of the tissue of interest
Mathematical Operation: Fourier Transformmation
Astrocytes Track Along WM
Anisotropy:Fractional anisotropy (FA) is different in different directions
Chemical shift is field independent!
H2O
NAA
CrPCr
Glu
Cho
Ins
H2O
NAA
CrPCr
Glu
Cho
Ins
CrPCr
CrPCr
NAANAA
6 5 4 3 2 1 0ppm
6 5 4 3 2 1 0ppm
Figure 1. 1H NMR Spectra of Human Brain at 4 Tesla (child): Grey matter (left) and white matter (right)
STEAM, TE = 6 ms, TR = 5 s, NT = 80, VOI = 8 ml
Gray matter White matter
Postoperative Brain TumorPre-op Immed post-op
4-mo post-op
1-mo post-op