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Brain Tumor Imaging
Caribbean Medical Providers Practicing Abroad
June 13, 2015
Asante M. Dickson, MD
CAQ Neuroradiology
Washington Adventist Hospital
Takoma Park, MD
Role of Imaging
Diagnosis Grade Guide Biopsy Monitor treatment response and prognosis
Post-operative base-line
Imaging Modalities Available
CT MRI PET
Pediatric
Supratentorial JPA juvenile pilocytic astrocytoma, Ganglioglioma,
PXA pleomorphic xanthoastrocytoma, PNET primitive neuroectodermal tumor, DNT dysembroplastic neuroepithelial tumor
Infratentorial JPA, Medulloblastoma, ATRT, Ependymoma,
Diffuse pontine glioma (Not usually intra-axial but don’t forget about
LCH and Neuroblastoma)
Medulloblastoma
4 year old
Brainstem Glioma
26 yo M
Craniopharyngioma
56 yo M
FLAIRT2
DWI
ADC
Intravascular Lymphoma
Post Gad
Okay, it’s a brain tumor – But then what ? WHO divides CNS neoplasms into 9 primary groups and mets
Neuroepithelial tumours (astrocytic, oligo, astroblastoma, ependymal, choroid plexus)
Neuronal, mixed glial-neuronal and neurocytic Pineal parenchymal tumors Embryonal tumors (PNET, medullo, ATRT) Peripheral neuroblastic tumors (neuroblastoma) Tumors of cranial, spinal or peripheral nerves Meningeal tumors (meningioma, chondrosarcoma,
hemangioblastoma) Lymphoma, hematopoietic tumors (leukemia, plasmacytoma) Germ Cell Tumors Metastases
The Approach to Differential Diagnosis
Where is it? Intra-axial Vs Extra-axial Cortical, white matter or deep grey matter, Intraventricular Supra-tentorial or Infra-tentorial
Solitary or Multiple How old is the patient?
Child, Young Adult, Older Adult, Ready to die of other causes Primary vs Secondary Is the patient immunocompromised? Other clinical history...
E.g. Lymphoma Imaging features – T2, DWI, PWI, MRS, Gad
Gamuts
Tumors in children <2yo Astrocytoma, CPP, Teratoma, Embryonal tumors
Cortically based tumors DNET, Ganglioglioma, Oligo, PXA(pleomorphic xanthoastrocytoma)
Intraventricular tumors Pineal Region tumors Dural Based tumors Intracranial extension from extracranial
Chordoma, paraganglioma, carcinomas (NPCA), sarcomas (rhabdo)
Cyst + Nodule Pilocytic, Craniopharyngioma, Ganglioglioma, Hemangioblastoma
Intra-axial vs Extra-axial Features Intra-axial
Surrounded by white matter
Expands cortex May destroy GM/WM jx Effaces CSF cisterns Internal vascular supply
Extra-axial CSF Cleft Widening of CSF cisterns Buckling of grey matter GM/WM junction
preserved Continuity with bone or
falx Bony changes External vascular supply
12yoM – Intra or Extra-axial?
Differential Diagnosis – Extra-axial Skull-base/calvarium Dural Sellar/Parasellar/Optic chiasm Perineural Intra-ventricular
Central neurocytoma, ependymoma, subependymoma, oligo, pilocytic astro, meningioma, choroid plexus tumour, epidermoid, subependymal giant cell astrocytoma, colloid cyst, arachnoid cyst
Pineal Region CP Angle
Pre T1 Post T1
Post T1 Post T1 Post T1
Post T1
56 yo M
Primary CNS Lymphoma
Diagnosis – Is it neoplastic?
Mass Lesions – The standard Ddx (Congenital) Infectious Inflammatory Neoplastic Vascular – Ischemic, Hemorrhagic (Toxic, Metabolic) (Traumatic) (Degenerative)
56year old male history of lung CA
FSE T2 DWI ADC
Post-Gad
Abscesses
19 yo Male, Previously well, presents with new onset of seizures x 3
MRI Same Day
DWI ADC GRE Post-Gad
5 Days Later
Post-Gad Pre-GadFSE T2
10 days after presentation
DWI ADC FSE T2
Post Gad Perfusion
15 days after presentation
FLAIR
GRE
Post-Gad
Supratentorial Neoplasms – Adults Metastases Infiltrative (Diffuse or fibrillary) astrocytic tumours
Astrocytoma, anaplastic astrocytoma, GBM, gliomatosis Localized/Noninfiltrative astrocytic tumours
(Pilocytic astrocytoma - peds), Pleomorphic xanthoastrocytoma, (supependymal giant cell astrocytoma)
Oligodendroglioma and anaplastic oligo Neuronal and Glial-neuronal composition
Gangliocytoma and ganglioglioma, (desmoplastic infantile ganglioglioma <1yo), (central neurocytoma), DNT
Primary CNS Lymphoma
GBM
Epithelioid Hemangioendothelioma
Mets from lung
Infratentorial Neoplasms - Adults Metastases Hemangioblastoma Medulloblastoma (Cerebellar astrocytoma, Ependymoma)
JPA
Proton MRS
Elevated choline:Creatine ratio and reduced NAA considered “tumor spectrum” but non-specific
Metabolic ratios for glioma grading remains investigational May be useful to help differentiate high vs low grade
gliomas (II vs III/IV) Lactate (high and low grades, ?radioresistance) vs Mobile
Lipids (high grade only) – can’t separate on standard MRS Imaging brain tumor after therapy – elevated choline
(>50% contralateral oe Ch:Cr >2) – moderate to high sensitivity and high specificity for identifying active tumor (but no large series)
MRS
TE 144 TE 35
Lactate inversion
NAA
ChoCr
Single Voxel
67 yo M
MR Perfusion – elevated relative CBV
MR Spectroscopy – increased choline, reduced NAA
Multivoxel
Grading of Brain Tumors
WHO grading revised in 2000 Based on histological appearance
Does not take into account anatomic location and size of tumor which influence resectability
Primary basis for guiding therapy, prognosis, scientific study
Diffusion Weighted Imaging and Grade Tumor grade and cellularity reflected by ADC values
But most astrocytomas are too heterogeneous for ADC values to be helpful
Post-operative injury Enhancement post-surgery may be subacute infarction
Peritumoral edema Vasogenic edema (mets and meningiomas) vs Tumoral
edema – not so helpful Integrity and Position of White Matter Tracts (DTI)
Tumor grade and cellularity
Higher cellularity, reduced ADC Minimum ADC may correlate inversely with
grade Limit due to tumor heterogeneity Non-glial neoplasms – Meningioma,
Lymphoma
MR Perfusion
Measures Degree of tumour angiogenesis and capillary permeability
CBV is proportional to the area under the contrast agent concentration-time curve Contrast concentration is proportional to the
change in relaxation rate (dR2*) Assumptions of negligible recirculation and
contrast leakage – generally violated Measurement is relative therefore compare to
contralateral white matter
MR Perfusion continued
Oligo’s – high CBV regardless of grade Astrocytomas – higher CBV = high grade Choroid plexus tumours, some meningiomas,
mets – may not return to baseline – contrast leakage/leaky capillaries
CNS Lymphoma – high but not as high as GBM
Tumefactive MS – intralesional venous enhancement, possible mild elevation of CBV
Permeability imaging (DCE steady-state T1 measurement or DSC) Endothelial permeability of vessels in brain tumors
gives info about BBB integrity, vascular morphology and nature of neovascularization
Quantitative estimates of microvascular permeability (Ktrans) correlate with brain tumour grade
Ktrans (endothelial transfer coefficient) is a generalized measure to decribe the relationship between the time course of blood plasma Gad concentration (arterial input function) and Gad concentration changes in the voxel Affected by blood flow, blood volume, endothelial surface
area, endothelial permeability
Monitoring Response to Therapy Post-operative Baseline Tumour recurrence vs radiation necrosis
48year old previously well
DWI Post-GadFLAIR
3 months later - Following one course of steroids
1 year following more steroids
11 months after presentation
13 months after initial presentation
MR Perfusion
11 months Perfusion
13 months Perfusion
FDG-18
Thank You very much !
Special thanks to Dr. Talia Vertinsky