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Neuroimaging > Brain tumours > Flashcards

Brain tumours Flashcards

1
Q

What are the two types of brain tumours, otherwise known as CNS neoplasms.

A

Primary and metastatic

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2
Q

What are the most frequent sources of metastatic tumours?

A

lung cancer, breast cancer and melanoma

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3
Q

What are glial cells?

A

Located in the CNS, they provide physical and chemical support to maintain their environment

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4
Q

What two types of glial cells are most likely to become cancerous? What are their roles?

A

Astrocytes - transport nutrients and holds neurons in place
Oligodendrocytes - provide insulation to neurons

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5
Q

What are the two other types of glial cells? What are their roles?

A

microglia - digest dead neurons and pathogens
Ependymal cells - line the ventricles and secrete cerebrospinal fluid

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6
Q

What are Gliomas?

A

An umbrella term for the tumours that originate from glial cells. They vary in aggressiveness/malignancy

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7
Q

What percentage of primary tumours are gliomas?

A

around 50%

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8
Q

what likely causes glial cells to be cancerous?

A

Their neural stem cell progenitors;
they keep regenerating themselves and this constant glycogenesis means a higher likelihood of mutation

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9
Q

What are the features of Grade 1 tumours

A

Benign, slow-growing circumscribed tumours
Cells look almost normal
Rare in adults
usually associated with long term survival
surgery alone most likely to be effective

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10
Q

What are the features of a grade 5 tumour?

A

Most malignant, fast-growing and actively producing
Spreads easily to nearby normal tissue
Cells look very abnormal under microscope
Tumour forms not blood vessels to sustain growth
Central areas of necrosis (dead tissue) are common

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11
Q

What is a big diagnosis contributor to the diagnosis of tumours?

A

Age

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11
Q

From what age do 50% of tumours are metastatic?

A

30-40 years old

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12
Q

What 3 ways do brain tumours produce signs and symptoms? What do the symptoms depend on?

A

Local brain invasion
Compression
Increased intracranial pressure
Depend on the function of the involved area?

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13
Q

What is the most common symptoms of tumours?

A

seizures; 50-80%

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14
Q

What might the focal signs of tumours be due to?

A

Local invasion, mass effect or vasogenic edema

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15
Q

What is vasogenic edema?

A

blood-brain barrier disruption causing tissue filled with water

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16
Q

What 4 neurocognitive symptoms can tumours cause?

A

Memory loss, personality/mood change, fatigue and lack of interest in everyday activities

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17
Q

What is evaluated in the battery for investigating low-grade gliomas?

A

Executive function, apraxia, language, memory and visuo-constructional abilities

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18
Q

What two neuroimaging techniques are used for assessing brain tumours?

A

CT and MR

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19
Q

When assessing a brain tumour, what things do we look for/think about?

A

Location, extension, the pattern of growth, structural categorisation, classification, grading, treatment planning and follow-up

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20
Q

What is a FLAIR scan in regards to MRI scanning? Why use it for brain tumours?

A

A type of T2 weighting where the CSF is suppressed
Allows to see the tumour better

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21
Q

What are the main goals of a diagnostic scan?

A

Detect the presence of a tumour - direct and indirect signs
Localise the tumour and define extension
Identify pattern of growth
characterise tumour’s macro- and microstructure

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22
Q

What are the four ways a tumour can be characterised

A

Extra and intra-axial (located in or out of the CNS)
Extra and intra-cerebral (originating or not from CNS cells)

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23
Q

What are the direct signs of brain tumour in CT and MRI scanning?

A

Increase water content caused by increased cellularity and increased interstitial fluids - CT hypodensity, high T2 and low T1 signal
Presence of regressive phenomena - cysts, necrosis, haemorrhages, calcifications, fatty degeneration
Vascular architecture - CT hypodensity, MR flow-void/enhancement.

24
Q

What are the indirect signs in CT and MRI scanning?

A

mass effect (pressure on brain), edema (trapped fluid) and bone alterations

25
Q

How do malignant gliomas, metastases and extra-axial tumours change the vascular architecture?

A

MG = formation of capillaries with fenestrated endothelium that leads to disruption of the blood-brain barrier
Metastases. = capillaries with the same properties as tissue from origin
extra-axial tumours= capillaries without tight junction

26
Q

How does contrast-enhanced T1 weighted MRI works?

A

gadolinium contrast (paramagnetic material that reduces the relaxation times) is injected into the patient
Travels to the brain vasculature
Contrast reaches capillaries
Normal BBB = stays in capillaries and remains invisible
Disrupted BBB = the contrast leaks into the tissue and creates a hyperintensity signal typically at the BOUNDARIES of the tumour

27
Q

What are the most useful contrasts for diagnosing tumours?

A

T2, FLAIR and contrast-enhanced T1

28
Q

What does advanced MRI add to the diagnosis of tumours?

A

adds important structural, hemodynamic and physiological information

29
Q

What are the 3 advanced MRI techniques?

A

Diffusion MRI, Perfusion MRI, MR spectroscopy

30
Q

What is Diffusion-Weighted MRI?

A

probes tissue water molecular diffusion over distances comparable to the size and spacing between the cells

31
Q

What is ADC?

A

Apparent Diffusion Coefficient - quantifies the water molecular mobility within tissues

32
Q

What is the relationship between ADC and cellularity

A

Reduced ADC = Increased cellularity = Decreased mobility of water to move around

33
Q

What does an increase in ADC mean?

A

vasogenic edema or widening of the extra-cellular structure due to matric degeneration

34
Q

What does a reduction in ADC mean?

A

Increased cellularity OR cytotoxic cell swelling

35
Q

What is tumour angiogenesis

A

When the tumour starts creating blood vessels into the tumour by sending out angiogenic factors (signals). This is so the tumour can be given fresh oxygen to survive

36
Q

What does perfusion-weighted imaging allow us to see? what two techniques do you use to do this?

A

neoangiogenesis
1. Dynamic Susceptibility Contrast-Enhanced (DSC)
2. Dynamic contrast-enhanced (DCE)

37
Q

What does DSC-MRI allow us to measure?

A

the intratumoral relative cerebral blood volume (rCBV)
rCBV proved to accurately predict the grading and outcome of patients with brain gliomas

38
Q

What is the relationship between the rCBV and grading?

A

Low grade = low rCBV
High grade = high rCBV

39
Q

What T weighting is DSC-MRI?

A

T2*

40
Q

What T weighting is DCE-MRI?

A

T1

41
Q

What can DCE-MRI quantify?

A

The tumour microvessel permeability and proliferation

42
Q

What the DCE-MRI allow us to measure?

A

Contrast Transfer constant (Ktrans) - vascular permeability
intra-vascular compartment volume - microvessel density

43
Q

What 3 ways can you treat brain tumours?

A

Microsurgical maximal safe resection
Chemotherapy
Radiation therapy

44
Q

What are the goals of surgery?

A

To obtain representative tissue samples for an integrated diagnosis
to delay (avoid) malignant transformation
to increase the progression-free survival (PFS)
to impact on overall survival (OS)
to contain symptoms (seizures/mass effect)
to maintain function integrity

45
Q

What is intraoperative stimulation brain mapping?

A

A group of techniques which allow to safely and effectively remove tumours and at the same time preserve functional integrity
apply electrical stimulation at cortical and subcortical level during resection and look for evoked responses either during rest or doing a task

46
Q

What impact has been shown from Intraoperative stimulation mapping?

A

Glioma resections using ISM have been associated with fewer late severe neurological deficits and more extensive resection (will remove more of the tumour knowing where not to touch more confidently)

47
Q

Why type of neurological functions do we want to preserve?

A

Motor-sensory, speech, vision
Language, memory, attention, exec functions, emotions, praxis and visuo-constructional abilities

48
Q

What are the two main pre-operative techniques? What do they help with?

A

fMRI = identification of eloquent cortical areas
MR tractography = identification of subcortical connections

49
Q

What relationship was found between pre-operative mapping with fMRI and intraoperative mapping with DES in Bizzi et al’s (2008) study?

A

There was a high concordance between them
High sensitivity and specificity of motor areas by fMRI

50
Q

What affects the diagnostic performance of fMRI validation?

A

the grade of the tumour

51
Q

What is language mapping?

A

aims to detect language functional sites at cortical and subcortical level during brain surgery

52
Q

What are 3 examples of language mapping paradigms?

A

Auditory Verb Generation, Verbal Fluency and Picture Naming

53
Q

Where in the brain was language localised for right-handed people?

A

The left hemisphere

54
Q

What test can we do to confirm the lateralisation of language?

A

WADA test - sends on side of the brain to sleep

55
Q

What is the problem with language mapping?

A

theres a great amount of interindividual variability

56
Q

What are the two streams of language?

A

Ventral and Dorsal?

57
Q

What does the ventral stream do?

A

maps acoustic speech inputs onto conceptual and semantic representations
supports the perception and recognition of auditory objects
bilateral

58
Q

What does the dorsal language stream do?

A

Supports sensory-motor integration
The stimulation causes speech arrest and phenomical paraphasia

Neuroimaging (11 decks)

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