basic approach to brain tumor

Basic approach in Brain Tumor imaging

Arunnit Boonrod

Three simple steps in radiographic interpretation

• Detection• Localization• Characterization

Detection

GBM Intraventricular astrocytoma

Meningioma

Chapter 11 Adult brain tumor, MRI of brain and spine 4th edition, Atlas

Detection

Anaplastic brainstem glioma

Brainstem astrocytoma


Localization

• Intra or extra axial tumor?– Intra-axial tumor =

tumor locates within brain parenchyma

– Extra-axial tumor = tumor locates outside the brain parenchyma, such as Skull, CSF cisterns and ventricles.

Sign of extra-axial locationDefinitive sign• CSF cleft between brain and lesion• Vessels interposed between brain and lesion• Cortex between brain and lesion• Dura (Meninges) between brain and lesion

Suggestive sign• Peripheral, broadly base along calvarium• Overlying bone change• Enhancement of adjacent meninges• Displaement of brain from the skull


Localization

• Specific location – Intra-axial Lobes, cortical base, periventricular,

midline crossing– Extra-axial CPA, sellar/ parasellar,

intraventricular (specific ventricle), pineal region, skull base tumor, etc.

CSF cleft (yellow arrow). Displaced subarachnoid vessels (blue arrow) Gray matter between lesion (curved red arrow). Widen subarachnoid space

90% CPA mass = schwannoma

Brain tumor-systematic approach, Radiology assistant

Characterization• Border

– Well or ill define– Localized or infiltrative

• Tumor tissue– Calcification– Hemorrhage– Cystic– Necrosis– Cellularity – Enhancement pattern

• Surrounding structures– Extension – Bone and dural change– Mass effect– Degree of perilesional brain edema

Common brain tumors

• Extra-axial tumor– Meningioma– Schwannoma– Epidermoid cyst

• Intra-axial tumor– Primary brain tumor; glioma– Secondary or brain metastasis

Extra-axial brain tumor

• 80% of extra-axial lesions = meningioma or a schwannoma.

• 75% of intra-axial = metastasis or astrocytoma

Brain tumor-systematic approach, Radiology assistant

Meningioma

• Most common nonglial primary brain tumor• 15-20% of primary brain tumor• Peak incidence 40-60 years• Female:Male = 2:1-4:1• Most common at parasagittal and convexity

Meningioma

CT• 70-75% hyperdense• 20-25% calcified• 90% enhanced strongly• 10-15% Cystic area• 60% Peritumoral edema• Hemorrhage rare• Bone change:

Hyperostosis, erosion, pneumosinus dilatans

MRI• Typically isointense

signal to gray matter• > 95% enhanced

strongly, commonly heterogeneous

• CSF/ Vascular cleft• 60 % dural tail

Chapter 14 meningioma and other nonglial neoplasms, Diagnostic neuroradiolgy, Anne Osborn.

Classic CPA meningioma. • A. Sagittal T1w and B. FLAIR show a

large mass deviating the cerebellum.

• C. T2w: homogeneous, low-signal-intensity mass with widening of the CPA cistern and deviation of the brainstem, findings characteristic of an extraaxial mass.

• D. After contrast, the mass enhances diffusely and shows the typical association of a dural tail of enhancement, a finding not seen with most other common cerebellopontine angle masses, such as acoustic schwannoma.


Schwannoma

• 6-8 % of primary brain tumor• Most common CPA mass (75-80%)• Peak incidence 50-60 years• Associated with NF-2

Chapter 15 Miscellaneous tumors, Diagnostic neuroradiolgy, Anne Osborn.

Schwannoma

• Cystic, hemorrhage• Less calcification• Peritumoral arachnoid cyst.• At CPA cistern– Intracanalicular component, widening of the porus

acusticus Trumpet sign– Extracanalicular extension into cerebellopontine

angle "ice-cream-cone" appearance.


www.headneckbrainandspine.com

Epidermoid cyst

T1: usually iso-intense to CSFT1 C+ :thin enhancement around the periphery may sometimes be seenT2: usually iso-intense to CSF (65%)FLAIR: often heterogeneous/dirty signal; higher than CSF Dirty CSFDWI: Restricted diffusion


Brain tumor

• Extra-axial tumor– Meningioma– Schwannoma– Epidermoid

• Intra-axial tumor– Primary brain tumor; glioma– Secondary or brain metastasis

Intra-axial brain masses• Most common intra-axial brain masses – high-grade primary neoplasms (36% of cases)– low-grade primary neoplasms (33%)– metastases (8%)– lymphoma (5%)– demyelinating and inflammatory conditions (3%)– infarcts (2%)– abscesses (1%)

TilgnerJ, Herr M, Ostertag C, Volk B. Validation of intraoperative diagnoses using smear preparations from stereotactic brain biopsies: intraoperative versus final diagnosis—influence of clinical factors. Neurosurgery2005; 56(2): 257–263.

Primary brain tumor: WHO Grading according to

Histology

Mitosis

Microproliferative vss

Necrosis

Imaging

Can’t see

MR perfusion (rCBV), enhancement

MRS, DWI

Low grade astrocytoma

Anaplastic astrocytoma

Glioblastoma (GBM)

Brain metastasis

• 40-70 yrs• For intracranial metastasis; intraaxial metastasis is

the most common form.– Lung, breast, melanoma, GI, RCC and unknown origin

• Usually multiple, but 30-50% solitary (esp. melanoma, lung, breast)

• Early deposit at gray-white junction (like other hematogeneous diseases)

Brain metastasis• Focal lesion at GW junction with extensive white matter edema• Extensive edema more than primary glioma or abscess.• Essentially all enhanced.• Cortical metastasis shows less edema might be seen only on post

contrast study.• Variable signals.• Variable types of enhancement.• Any patient with a primary cancer with intracranial enhancement in a

non vascular distribution, metastases should be considered the diagnosis until proven otherwise.

Brain metastasis

Take home messages • Three simple steps – Detection– Localization– Characterization

• Sign of extra-axial location– CSF, Vessels, Cortex or Dura between brain

and lesion

Thank you for your attention

• Chapter 11 Adult brain tumor, MRI of brain and spine 4th edition, Atlas • Brain tumor-systematic approach, Radiology assistant • Chapter 14 meningioma and other nonglial neoplasms, Diagnostic

neuroradiolgy, Anne Osborn. • Chapter 15 Miscellaneous tumors, Diagnostic neuroradiolgy, Anne

Osborn. • www.headneckbrainandspine.com • TilgnerJ, Herr M, Ostertag C, Volk B. Validation of intraoperative

diagnoses using smear preparations from stereotactic brain biopsies: intraoperative versus final diagnosis—influence of clinical factors. Neurosurgery2005; 56(2): 257–263.

Referrences

basic approach to brain tumor

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