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Imaging Knowledge You Should Know for Diagnosis of Brain Tumors

陽明交通大學 醫學院醫學系放射線學科 教授

臺北榮總影像診療部

凌憬峯

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The annual incidence of primary intracranial malignancies is 11–19/100,000 persons.

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Metastases to the brain from a systemic

primary are at least 10 times more common.

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Generalized symptoms result from increased intracranial pressure

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Metastases

  • Metastases are by far the most common supratentorial and infratentorial neoplasms in adults, accounting more than 40% of all tumors
  • About half of these lesions are reported to be solitary
  • In decreasing order of numbers, metastases tend to arise from the lung (50%), breast (15%, in women), melanoma (11%), kidney, and gastrointestinal primaries.

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  • focal symptoms reflecting the affected area of the brain.

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  • rapidly growing tumors often exhibiting symptoms earlier, with less overall tumor bulk than a more slowly growing tumor that allows time for accommodation by the surrounding structures.

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Brain CT

  • Unenhanced CT of the brain is considered the first line of imaging to evaluate patients with suspected brain tumor who present with acute symptoms.
  • CT is widely available, fast and easy to perform, it is very sensitive in detecting acute hemorrhage, hydrocephalus, herniation and calcification.

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Brain CT

  • Contrast-enhanced CT can be helpful in detecting areas of BBB and defining the contrast-enhancing tumor border.
  • CT suffers from several important limitations

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Brain CT

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  • not optimally suited for detecting subtle changes in brain

parenchyma, such as nonenhancing tumor or infiltrative

changes, because of its intrinsically low soft tissue contrast

  • ionizing radiation
  • iodinated contrast agent can cause serious allergic reaction
  • CT is primarily reserved as an initial screening method to exclude potentially life-threatening intracranial process

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清醒一下，請大家寫下答案

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Magnetic Resonance Imaging (MRI)

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  • Magnetic resonance imaging is the imaging study of choice for patients with brain tumor before or after therapy
  • Intravenous MRI contrast agent, gadolinium
  • Contrast-enhanced MRI provides exquisite anatomical detail, has multiplanar capability, and does not require ionizing radiation

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Magnetic Resonance Imaging (MRI)

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  • Contrast-enhanced T1-weighted imaging is among the most important MRI sequences for characterization of brain tumor.
  • The areas of contrast enhancement on T1- weighted images represent regions of BBB breakdown, in which gadolinium has leaked out. This is a process more commonly seen with aggressive neoplasms, such as high-grade glioma.
  • Contrast-enhancing tumor is not, however, synonymous with a malignant brain tumor. Indolent or less aggressive tumors, such as pilocytic astrocytomas or meningiomas, often demonstrate contrast enhancement.

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

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🡺 correct location of the origin of the mass

* within the brain parenchyma (intra-axial)

* outside the brain parenchyma (extra-axial,

in which case symptoms are usually due to

compression of subjacent brain)

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

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🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

​

🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

​

🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

​

🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

​

🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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IMAGING FEATURES

  • How to reach an intracranial tumors ?

​

🡺 radiologic clues that a tumor is extra-axial include :

1) widening of the ipsilateral subarachnoid space

2) cerebrospinal fluid (CSF) cleft between the mass and

brain parenchyma

3) deviation of pial vessels between the mass and brain

tissue

4) buckling of the gray matter (GM)/white matter (WM)

junction

5) broad base along the dural or calvarial surface

6) adjacent bony changes, such as hyperostosis in

meningioma

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  • Conventional MRI

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🡺 accurate compartmentalization of the mass

limiting the differential diagnosis

🡺 the other imaging features often leading to the

correct diagnosis.

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IMAGING FEATURES

  • Conventional MRI

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  • enhancement reflecting the breakdown of the

blood–brain barrier (BBB), which is normally

absent in structures such as the pituitary gland,

pineal gland, choroids plexus, and meninges.

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IMAGING FEATURES

  • Advanced MRI

advances in MRI are helping researchers investigate

the biological nature of tumors rather than the subsequent anatomical changes.

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Advanced MRI�

  • Diffusion Tensor Imaging (DTI) and MR neural tractography (corticospinal tract)
  • MR Spectroscopy (MRS) (metabolites)
  • Perfusion MRI (angiogenesis, treatment F/U)
  • Functional MRI (fMRI) (critical area vs tumor)

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9 y/o girl with seizure and brain tumor

IBRU, Taipei VGH

R

R

R

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IBRU, Taipei VGH

Presurgical Mapping for Language Dominance

9 y/o girl with seizure and brain tumor

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Task: silent reading to visually displayed words.

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第三次動動腦:

腦部結構中，沒有ＢＢＢ的結構有哪些？寫出三個。

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Glial and Neuronal Intra-Axial Tumors

  • Astrocytomas are the most common primary intra-axial mass in adults, mainly supratentorially.
  • Brainstem gliomas account for 1% tumors in adults and 10% to 20% of tumors in children.
  • MR shows T2 hyperintensity and T1 hypointensity with mass effect and variable enhancement.

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Extra-axial Tumors

  • Meningioma is the most common extra-axial neoplasm of adults, representing 20% of all primary intracranial tumors.
  • These are twice as common in females and occur most often in middle-aged patients.
  • Symptoms are related to the location, with common sites being the parasagittal and convexity dura, sphenoid ridge, and parasellar and CPAs (cerebellopontine angle).
  • Parasagittal meningiomas have a propensity to invade the dural venous sinuses
  • Parasellar meningiomas, resulting in encasement of cavernous sinuses and narrowing of the internal carotid arteries.

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Extra-Axial Tumors�(meningiomas)

  • There may be a bony reaction in the adjacent skull, usually hyperostosis due to stimulation of a bony reaction through growth into the haversian canals, and less frequently to bone destruction.
  • They show T1 and T2 isointensity relative to the cortex.

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Pituitary Adenomas

  • Pituitary adenomas represent 33% to 50% of all sellar and parasellar masses.
  • In 66% to 75%, the tumors are hormonally active and likely to present earlier than the endocrine dysfunction. The hormones include growth hormone, adrenocorticotropin, prolactin, and thyrotropin.
  • Hormonally-inactive tumors present at larger sizes due to mass effect on adjacent structures.
  • Microadenomas (10 mm)

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叮嚀

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天氣冷

深夜苦讀一定要添衣穿暖

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四下功課更重

大家辛苦了 加油 加油

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驗收今天自己聽課的成果。

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