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Multiple Sclerosis

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Ann Pham

on 15 October 2014

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Transcript of Multiple Sclerosis

Limitations of non-contrast T1 & T2 weighted image
Signs & Symptoms
(Rae-Grant, Fox & Béthoux, 2013)
Multiple Sclerosis
Multiple sclerosis is a chronic, neurodegenerative condition that affects the central nervous system, characterised by the presence of multifocal, demyelinated plaques which largely involves the brain, spinal cord and optic nerves.
At the Cellular Level:

Clinical Indications
Primary Symptoms
directly affects the CNS
Secondary Symptoms
result of the primary symptoms
Problem
It is hard to determine initially whether these secondary symptoms are related to primary MS symptoms.
Common Symptoms:
o Vision loss
o Motor complaints (Almuntashri & Aviv, 2011)
o L’Hermitt’s sign
o Fatigue, depression, headaches and back pain can also be apparent in patients with MS.
o Cognitive impairment

Table 1: Tsang, B. K-T, & MacDonell, R. (2011). Multiple sclerosis: Diagnosis, management and prognosis. Australian Family Physician, Vol. 40, No. 12, 948-955.
Case Scenario
(Rae-Grant, Fox & Béthoux, 2013)
Penny Jones is a 23 year old Caucasian female. In the past 6 months she has developed pain at the back of her left eye which was worse with movement. She has also got tingling sensations on her toes on both feet and this sensation has ascended all the way up to her chest just recently. This was associated with sense of unsteadiness with walking and also trouble initiating urination. Whenever she moves her neck she gets the same tingling sensation but across her arms and shoulders. She has also noticed that she gets tired much more quickly than usual. Over the 3 days she has progressively lost central vision in that eye with impaired colour vision and decreased light brightness which spontaneously resolved 3 weeks later.
Radiographer's Role:
Take extra clinical history in particular to the timing of the occurrence of the symptoms
Long-lasting symptoms
(48-72hrs to several weeks)
indicates progressive myelopathy
Short-lasting symptoms
(few seconds)
similar to seizures and unconsciousness except they also affect sensory and motor neurons.
Radiographer needs to be in mind not to assume immediately of such clinical symptoms to the scans as there could be other factors influencing such pain and change in sensations.
0.1% (23,700)
of the Australian population diagnosed with MS in 2009

of people with MS possess severe core-activity limitations
48%
Anatomy & Pathology
Figure 1: http://www.neuroanatomy.wisc.edu/SClinic/Weakness/myelin1.JPG
Usually, MS affects the white matter of the brain as it contains more myelin than in grey matter, but it can appear in both. White matter lesions can be either vascular lesions or MS lesions and can be differentiated by their location.

Specifically, it affects the myelin sheaths surrounding nerve fibres (Amor & van Noort, 2012).
Oligodendrocytes
support and insulate axons and produce myelin
Microglia
main form of active immune defence in the CNS -digests waste products and debris
(Binder, Hirokawa and Windhorst, 2009)
Blood brain barrier
prevents most infections from reaching the brain and spinal cord
(ABC Science, 2013)
Astrocytes
star like cells which provide nutrients, support and neuron insulation
Figure 2: http://4.bp.blogspot.com/_Um_MFFpjTxg/TIiqvJL9pDI/AAAAAAAAAuA/OCtzxC-o5L4/s1600/1_1257234936.gif
What happens to patients with multiple sclerosis?
Changes in oligodendrocytes
Microglia activation and increased production of MHC proteins
Immune reaction occurs producing MS lesions
White blood cells enter the tissue and travel to the "damaged" site
(Amor & van Noort, 2012)
Myelin covering the nerve fibre is damaged
Remyelination

Figure 3: http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/14463695/f2_franklin_nrn2480-f1.jpg
Scar formation
(Murray, Saunders and Holland, 2012)
Nerve signals are unable to be transmitted, resulting in loss or impairment of function
Figure 4: http://uppercervicalcare101.com/upper-cervical/normal.png
(Schidmt & Willis, 2007)
(Martin, 2010)
MS lesions in the Brain:
Inner surface of the corpus callosum
U-fibres - juxtacortical region
Periventricular white matter
Juxtacortical lesions and temporal lobe involvement

Multiple sclerosis brain lesions are most commonly found in:
BLUE ------>
GREEN ---->
YELLOW -->
RED ------->
Dawson's Fingers:
specific sign for multiple sclerosis
appears perpendicularly to the lateral ventricles

Figure 5: Common locations of brain lesions
http://www.radiologyassistant.nl/data/bin/w440/a50979777c67af_typ-MS2b.jpg
Figure 6: Dawson's Fingers sign
http://images.radiopaedia.org/images/562/014cd18453a1b963e17e97cf4ec5c3_gallery.jpg
MS lesions in the Spine:
(Weiner & Stankiewicz, 2012)
Appear peripherally
Most commonly in the cervical spine

Figure 7: Spinal cord lesion
http://www.radiologyassistant.nl/data/bin/w440/a51910e08181d7_15-MS-typisch.jpg
Optic Neuritis:
is the inflammation of the optic nerve(s)
it is a strong indicator for MS
Figure 7: Optic Neuritis
http://img.medscape.com/pi/emed/ckb/radiology/336139-383642-1421.jpg

No known cause for multiple sclerosis
Normal immune system
No particular bacteria/virus associated with MS
Currently:
(Murray, Saunders and Holland, 2012)
The causes of MS are unknown:
? genetic and environmental factors

Majority of cases:
MS begins with an acute episode of neurological disturbance, which is followed by relapse and remission.

MRI Sequences for Multiple Sclerosis
MRI protocol for assessment of MS in the brain includes:
(Porter, 2014)
axial T1,T2, DWI,
sagittal T1,
axial T1+contrast
coronal T1+contrast

FLAIR
FLAIR
FLAIR MRI
very sensitive in detecting MS lesions in the cerebral hemispheres and in periventricular regions

superior at detecting cortical and juxtacortical lesions

MS lesions occurring in grey matter is best visualised using a FLAIR sequence

sagittal FLAIR image shows ‘Dawson fingers’ appearance
(Porter, 2014)
(Trip & Miller, 2005)
(Ge, 2006)
(Porter, 2014)
Figure 8: MS lesion (arrow) in corpus callosum
Image from: Ge, Y. (2006). Multiple Sclerosis: The Role of MR Imaging. American Journal of Neuroradiology, 27(6), 1165.
Figure 9: Image from: Hashemi, R.H. (2000). Advanced Topics in Neuroradiology: value of MRI FLAIR Sequence in Multiple Sclerosis. Retreived October 4, 2014, from http://www.aiclancaster.com/Referring%20Doctors/Newsletters/nl_081400.htm
Use of Contrast
gadolinium contrast allows differentiation between active and inactive MS lesions


allows lesions to be distinguished from other conditions such as neoplasms and vascular malformations


contrast enhanced T1- weighted MRI scans show acute, active lesions appearing as enhancing white matter lesions


allows detection of blood-brain barrier breakdown associated with active inflammation


T1 images using contrast provide information about its dissemination in time and space
(Porter, 2014)
(Weiner, & Stankiewicz, 2012)
(Wilson, 2014, “Typical findings and pulse sequences”, para. 6)
(Trip & Miller, 2005)
(Weiner, & Stankiewicz, 2012)
Figure 10:
(A) T2WI
(B) FLAIR
(C) Contrast-enhanced T1WI
Image from: Ge, Y. (2006). Multiple Sclerosis: The Role of MR Imaging. American Journal of Neuroradiology, 27(6), 1165.
enhancing lesions appear hypointense
Non-contrast T1-weighted images
(Van Waesberghe et al., 1998)
Figure 11:
(A) contrast-enhanced T1-weighted image
(B) corresponding unenhanced T1-weighted image at the time of initial enhancement
(C) corresponding unenhanced T1-weighted image after 6 months
Image from: Van Waesberghe, J.H.T.M., Van Walderveen, M.A.A., Castelijins, J.A., Scheltens, P., Lycklama a Nijeholt, G.J., Polman, C.H., & Barkhof, F. (1998). Patterns of Lesion Development in Multiple Sclerosis: Longitudinal Observations with T1- Weighted Spin-Echo and Magnetization Transfer MR. American Journal of Neuroradiology, 19, 675-683.
hyperintense lesions are non-specific and its signal intensity can change when brain tissue composition is altered
Non-contrast T2-weighted images
(Sahraian, & Radue, 2008)
difficult to distinguish periventricular lesions
(Trip & Miller, 2005)
Figure 12:
(A) T2- weighted image
(B) Proton density weighted image
(C) FLAIR
(D) T1 weighted image with contrast
Image from: Trip, S. A., & Miller, D. H. (2005). Imaging in multiple sclerosis.Journal of Neurology, Neurosurgery, and Psychiatry,76(Supplement 3), iii11-iii18. doi:10.1136/jnnp.2005.073213
Safety Issues & Artefacts
Generic Safety Issues
strong magnetic field
ferromagnetic objects
missile effect
translational attraction and torque
aneurysm clips, foreign body, metallic implants, oxygen tank
(Dempsey, Condon & Hadley, 2002)
internal ferromagnetic objects
movement, discomfort, physical harm
Iron oxide in skin staples, tattoos or eye shadow may cause warmth
(The Royal Australian and New Zealand College of Radiologists [RANZCR], 2007)
heat is produced from the induction in the conducting loops
due to increase in RF pulse.
lead to skin burns and nerve stimulation
(Dempsey, et.al., 2002)
Safety Checklist
MUST fill in and sign a consent form and safety questionnaire
Figure 13: (Melbourne Radiology Clinic, 2014)
Mental Issues: A chaperone with a close relation to the patient can assist in filling the form & ensure all information is understood by the patient.
Preparation
removal of any potential ferromagnetic material
Metal
x-ray for confirmation
Specific Safety Issues
is fatigued or has muscle stiffness or spasms
is unable to remain in the machine for the duration of the examination
If a patient:
exam will need to cease
quench button
Chaperone will be present during procedure behind screen
MS patients: numbness or loss of sensation
Radiographers need to be prepared for these examinations
e.g. defibrillator, oxygen tank or other equipment used in resuscitation situation must be MRI safe.
MS patient may feel more at ease knowing someone they know is there
may not feel skin burns
(Aguilar, 2004)
Radiographers will take extra precautions!
Artefacts
(Somasundaram & Kalavathi, 2012)
Chemical shift
Aliasing/wrap around
Black line
Zipper
Entry slice (inflow) phenomenon
Ferromagnetic implants
Slice overlap/cross-slice
Moire fringe
RF overflow/clipping
Central point
Quadrature ghost
Susceptibility
Eddy current
RF inhomogeneity
Gradient failure
Partial volume
Flow
RF noise
Motion Artefact
extensive duration of brain scan
internal movements
e.g. swallowing & respiration
blurring and ghosting due to inconsistencies in phase and amplitude
patient movement
Figure 14: Motion artefact in the brain.
(Somasundaram & Kalavathi, 2012)
Pulsation Artefact
intrinsic movement of CSF in FLAIR images
CSF flow ghosting artefact
flow in upper spine causes flow void
T2 weighted image
intensity change from CSF (bright) to spinal cord (dark) leading to parallel lines
Figure 15: Gibbs ringing artefact in the brain.
(Somasundaram & Kalavathi, 2012)
Gibbs Ringing
Alternative Imaging
References
Positron Emission Tomography
(Ramil, Rahmat & Azmi, 2009)
Computed Tomography
(Ramil, Rahmat & Azmi, 2009)
First imaging modality before MRI
Unable to show lesions outside the brain such as spinal cord
Inferior capability in showing intracranial lesions


MRI more superior of 90-97% detection rate

risks weigh up greater than benefits
Figure 16: Basic principles and procedures in PET Imaging
(de Paul Faria, Copray, Buchpiguel, Dierckx & de Vries, 2014)
Allows imaging of different MS indications
oedema, inflammation, demyelination and axonal loss
increased understanding and knowledge of disease characteristics in a non-invasive method
(de Paul Faria, Copray, Buchpiguel, Dierckx & de Vries, 2014)
Superior evaluation of therapeutic procedure progress and follow up.
Positive future in the use of bio-markers
e.g. trace glucose metabolism for the presence of sclerotic lesions
C-PK 1195 PET tracer
11
evaluate microglial involvement in MS
(Anonymous,2003).
Further support from 2010 International panel on the diagnostic criteria of MS:
Increase sensitivity and specificity by using bio-makers specifically targeting anti-bodies for the assessment of the degree of MS disease.
Optical Coherence Tomography (OCT) & Visual Evoked Potentials (VEPs)
(Frohman, Balcer & Calabresi, 2010)
Both imaging diagnoses optic neuritis.
OCT:
Evaluates axonal and neural degeneration via retinal nerve fibre layer (RNFL) and macular volume.
(Frohman et al., 2010)
Provide structural evaluation of the retina
VEP:
Measures the time taken for visually evoked stimuli to travel to the occipital lobe
(Frohman et al., 2010)
Higher sensitivity in detecting optic neuritis
identifies correctly 75% of the time
Less complementary than OCT
affected by changes in homeostasis
Magnetic Resonance Imaging
Refinement Strategies
Increasing the magnetic field strength
(Polman et al., 2011)
Better visualisation of lesions by improving SNR, image resolution and chemical shift
7.0T – increased detection of lesions however ? safety

Problem of mimicking other pathologies

Magnetic transfer imaging assesses damage outside the focal lesions

e.g. ADEM and NMO
(Polman et al., 2011)
Solution:
Figure 17: Axial T2-weighted images with multiple hyperintensity in the occipital lobe, midbrain and the periventricular regions.
(Ramil et al., 2009)
Use of new advanced techniques improving visualisation in other MS hallmarks
Cell specific MS - tagging of iron oxide markers to macrophages and T-cells
Proton MRS – uses biomarkers to assess treatment of lesions
MTI – axonal loss and demyelination
DTI – acute and chronic pathological changes


(Ramil et al., 2009)
Cell-specific MR contrast
Proton MRS
MTI
DTI
monitor inflammatory processes in MS tagging small-particle iron oxide to macrophages and T-cells
assesses neuronal health through the measurement of biomarkers within the lesion & assesses legion progress and follow-up from treatment
indicates axonal loss and demyelination
assessed acute and chronic pathological changes, good for follow-up from treatment. With MTI very sensitive in differentiating acute plaque (inflammation and oedema) and chronic plaque.

gadolinium contrast allows differentiation between active and inactive MS lesions

allows lesions to be distinguished from other conditions such as neoplasms and vascular malformations

contrast enhanced T1-weighted MRI scans show acute, active lesions appearing as enhancing white matter lesions

allows detection of blood-brain barrier breakdown associated with active inflammation

T1 images using contrast provide information about its dissemination in time and space
(Wilson, 2014, “Typical findings and pulse sequences”, para. 6)
(Weiner, & Stankiewicz, 2012)
(Trip & Miller, 2005)
(Weiner, & Stankiewicz, 2012)
(Porter, 2014)
Non-contrast T1-weighted images
Non-contrast T2-weighted images
enhancing lesions appear hypointense
hyperintense lesions are non-specific and its signal intensity can change when brain tissue composition is altered
Multiple sclerosis is a chronic, neurodegenerative condition that affects the central nervous system, characterised by the presence of multifocal, demyelinated plaques which largely involves the brain, spinal cord and optic nerves.
What is Multiple Sclerosis?
Full transcript