FINAL YEAR NEUROSURGERY PRESENTATION

1. BASIC PRINCIPLES OF MRI OF
INTRACRANIAL LESIONS
DR ADEBIYI JAMIU
NEUROSURGERY UNIT
NATIONAL HOSPITAL ABUJA

2. OUTLINE
• INTRODUCTION
• PHYSICS OF MRI
• BASIC MRI SEQUENCES
• PRINCIPLES
• MRI in Neurosurgery
– Pre-operative
– Intra-operative
– Post-operative
– Others
• PRINCIPLES OF IMAGING
– Pre-imaging
– Imaging
– Post-imaging
• MRI OF SOME INTRACRANIAL LESIONS
• CURRENT/FUTURE TRENDS
• CONCLUSION

3. INTRODUCTION
• MRI is a medical imaging technique used
mostly in radiology and nuclear medicine in
order to investigate the anatomy and
physiology of the body and to detect
pathologies.
• Intracranial lesions.

4. HISTORY OF MRI
• Discovered by 2
physicists in 1947
– Felix Bloch
– Edward Mills Purcel
• First Clinical Images-
1977
• Nobel Prize in Medicine
in 2003
– Paul Lauterbur
– Peter Mansfield

5. INTRODUCTION
• Magnetic flux density is measured in Tesla (T)
• Clinical MRI : 1.5-3T
• 50X of earth magnetic field
• MRI relies on the magentic ppties H+ to
produce images.

6. PHYSICS OF MRI

7. BASIC MRI COMPONENTS
• PRIMARY MAGNET
• GRADIENT
MAGNET
• RADIOFREQUENCY
(RF) COILS
• COMPUTER
SYSYEMS

8. PHYSICS OF MRI
• Repetition Time (TR):time between successive
pulse sequences applied to the same slice.
• Time to Echo (TE) :time between the delivery
of the RF pulse and the receipt of the echo
signal.

9. PHYSICS OF MRI

10. BASIC MRI SEQUENCES
What Protocol to use ?
• Scout.
• T1W, T2W
• FLAIR
• Post Gd T1W.
• DWI & ADC.
• MRI Perfusion.
• MRS
• GRE.
What is each sequence telling us
about SOL?
• Size of the lesion.
• Location
• Number
• Outline
• Perilesional oedema.
• Necrosis.
• Fat.
• Protein rich substances.
• Calcification.
• Haemorrhage.
• Cysts.

11. BASIC SEQUENCES OF MRI-T1WI
T1 WEIGHTED IMAGE ANATOMIC IMAGE
• Fat- Dark
• Fluid : Dark
• Gray matter: Gray
• White matter: White
• Vessels: Dark
• Useful for: Evaluating
anatomic detail

12. BASIC SEQUENCES OF MRI-T1WI
BRIGHT ON T1
• Fat
• Subacute haemorrhage
• Melanin
• Protein rich fluid.
• Slowly flowing blood
• Paramagnetic substances
(Gd,Cu,Mn)
DARK ON T1
• Edema
• Tumour
• Infection & inflammation
• Haemorrhage (hyperacute,
chronic)
• Calcification(in all
sequences)
• Flow void

13. BASIC SEQUENCES OF MRI-T2WI
T2 WEIGHTED IMAGE PATHOLOGIC IMAGE
• Fat- Bright
• Fluid/CSF-Bright
• Gray matter-Bright
• White matter –Dark
• (Reverse anatomy)
• Useful for: Looking at areas
of edema & pathology

14. BASIC SEQUENCES OF MRI
BRIGHT ON T2
• Perilesional oedema
• Tumour
• Infection & Inflammation
• Subdural collection
• Methemoglobin in late sub
acute haemorrhage.
DARK ON T2
• Calcification,
• Fibrous tissue
• Paramagnetic substances
(deoxyhemoglobin,ferritin,hemosiderin,m
elanin).
• Protein rich fluid
• Flow void

15. BASIC SEQUENCES OF MRI-FLAIR
FLUID ATTENUATION INVERSION
RECOVERY
• Similar to T2WI
with signal from
free water(eg
CSF)suppressed.
• Most pathology
exhibits signal on
FLAIR

16. BASIC SEQUENCES OF MRI-FLAIR

17. BASIC SEQUENCES OF MRI-T1WI,T2WI & FLAIR

18. DWI/ADC
• Diffusion Weighted Images (DWI) & Apparent
Diffusion Coefficient (ADC) :
• DWI is an inherently T2WI
• Reduced or restricted diffusivity will be
hyperintense
( …less Brownian motion >> less loss of signal)
– lesions are very conspicuous)

19. DWI/ADC
Abnormal increase signal
on DWI.
If they are dark on ADC=
True restricted diffusion.

20. T2 SHINE THROUGH
If the focus is
bright on both
DWI/ADC,then the
signal is related to
T2 shine through

21. DWI/ADC
• Causes of Restricted diffusion:
Acute infarct(mins -5/7 days)
Bacterial Abscess
Tumors (Lymphoma,medulloblastoma,GBM)
Epidermoid Cyst
Herpes Encephalitis
Creutzfeldt-Jakob Disease

22. GRE

23. T1WI+ C

24. 3D HEAVILY T2WI-For CNs

25. MR SPECTROSCOPY
• Proton MRS provides a noninvasive method
for characterizing the cellular biochemistry
which underlies brain pathologies.

27. APPLICATION OF MRS
LOW GRADE TUMOUR
• Low -NAA
• High - Choline
• High- Myo-inositoI
• High- Lactate
HIGH GRADE TUMOUR
• NAA – very low
• Creatinine- low
• Choline – very high
• Lactate- High
• Lipids- high

29. FUNCTIONAL MRI
• fMRI detects the blood oxygen level–
dependent (BOLD) changes in the MRI signal
that arise when changes in neuronal activity
occur following a change in brain state.
• An increase in neural activity in a region of
cortex stimulates an increase in the local
blood flow in order to meet the larger
demand for oxygen and other substrates.

30. fMRI

33. PRINCIPLES OF MRI REPORTING
• Strenght MRI:
• Planes: Axial, Sagital, Coronal
• Sequence:
– T1,
– T2,
– T1 VsT1+C,
– T2 Vs FLAIR
– DWI Vs ADC
• Abnormalities & lesions xter
• Intensity
• Anatomical location of lesions
• Pattern of enhancement
• Important normal findings

34. MRI OF INTRACRANIAL LESIONS
• The First Principle
• History: on request card
• Physical examination:(esp CNS exams)
• sEUCr-contrast; Gd
• Clinical Diagnosis
• Radiological Diagnosis: MRI,CT or both
• Histological Diagnosis:- The final arbiter!

35. PRINCIPLES OF MRI IN
NEUROSURGERY
• Pre-operative
– Diagnosis
– Differentiating between differential diagnoses
– Planning for surgery
• Intraoperative
– Lesion localization
– Assessing of extent of intervention
• Post-operative
– Assessing of extent of intervention
– Diagnosing complications
– Detecting recurrence
• e.g. differentiating recurrent tumour from radiation necrosis - PWI
– Monitoring residual lesions
• Others
– Screening
– ??

36. PRINCIPLES OF IMAGING
• Pre-imaging
– Establish indication
– Establish safety
– Informed consent
• Imaging
– Reaffirm safety of intended procedure
– IV access
– Safety measures
• Post-imaging
– Management of complications if any
– Re-imaging (if required)

37. MRI
• Advantages
• Disadvantages
• Contraindications:

38. INDICATIONS FOR BRAIN MRI
• SCREENING
• DIAGNOSIS
• INTRA OP
• POST SURGICAL IMAGING
• POST TREATMENT FOLLOW UP

39. INDICATIONS/CONTRAINDICATIONS
INDICATIONS CONTRAINDICATIONS CAUTION
Neoplasm
- primary
- secondary
Vascular
Degenerative
Spine trauma
Infections/inflam
matory
Epilepsy
Developmental
Non-MRI compatible metallic
implants
Non-MRI compatible foreign bodies
e.g. gunshot
Unstable patients
Nearby metallic
objects
Claustrophobic pts
(sedate)
Pregnancy esp with
contrast

40. MRI OF INTRACRANIAL LESIONS
• Congenital lesions
• Acquired
– Tumours
– Infections
– Haemorrhage/Trauma
• Size of the lesion.
• Location
• Number
• Outline
• Perilesional oedema.
• Necrosis.
• Fat.
• Protein rich substances.
• Calcification.
• Haemorrhage.
• Cysts.

41. MRI OF INTRACRANIAL LESIONS
• CONGENITAL LESIONS

42. A male neonate with
severe hydrocephalus
FINDINGS .
-Axial T2WI through the lateral
ventricles.
There is smooth brain surface
-Coronal T2WI through the sylvian
fissures.
There is hypoplasia of the
periventricular white matter (WM).
There is hour glass deformity of the
cerebral hemispheres
There is hypoplasia of the WM.
Hydrocephalus
Presenting with
lissecephaly

43. 18-year-old lady with
seizures.
FINDINGS
-Sagittal T1WI through the
level of aqueduct(narrow).
--Axial FLAIR through the
body of the lateral
ventricles.
-Coronal T2WI through the
aqueduct.
-Axial post-contrast T1WI
through the aqueduct.
Hydrocephalus secondary
to aqueductal stenosis

44. 26-year-old lady with
dizziness
FINDINGS
-Sagittal T1WI through the 4th
ventricle.
-Axial FLAIR through the level
of the foramen magnum.
Chiari 1 malformation

45. 5-year-old girl with
paraesthesia in bilateral
upper extremities.
FINDINGS
-Sagittal MR T1WI.
-Axial T2WI through the small
posterior fossa.
-Axial FLAIR through the
lateral ventricles.
-Axial T2WI through midbrain.
Beaked tectum protrudes into
dilated quadrigeminal cistern.
Chiari II malformation
(CIIM).

46. 21-year-old female with
headache.
Findings
-Axial NCCT through 4th ventricle.
Large 4th ventricle ballooned into
a large dorsal P. fossa cyst with
remodeling of the occipital
bone.
-Sagittal MRI T1WI through the
4th ventricle-Large P fossa cyst.
Axial T2WI through the fourth
ventricle.
-Coronal T2WI through the fourth
ventricle.
Dandy-Walker malformation
(DWM).

47. MRI OF INTRACRANIAL LESIONS
• ACQUIRED LESIONS
• TUMOURS

48. MRI OF INTRACRANIAL LESIONS
• Peritumoral Oedema
• Vasogenic cerebral
• Mainly affects the white
matter, through leakage
of fluid out of capillaries.
• Minor or major, rounded
or irregular.
• 1° or 2° BT
• Non tumourous
conditions

49. MRI OF INTRACRANIAL LESIONS
• Necrosis
• Caused by sudden
vascular occlusion.
• Endothelial proliferation
and thrombosis
• Poor prognosis in adult
glioma.

50. MRI OF INTRACRANIAL LESIONS
• Haemorrhage
• Due to pathological
changes in the tumor
vessels.
• Typical of malignant
tumors.
• Haemorrhagic
metastatic melanoma.

51. • Cyst
• Neoplastic cysts (arises
within the tumor &
has enhancing walls).
• Non neoplastic cysts
(reactive,arising in the
neighbouring parenchyma
mural enhancement is
absent).

52. 63 year old woman with
history of breast Cancer.
-Axial post-contrast T1WI
through the corona radiata
-Axial T2WI and FLAIR through
the mass.
-Axial ADC map through the
lesion.
-Hyperintensity of the WM
around the mass indicative
of increased diffusivity and
lack of restricted diffusion.
Vasogenic oedema
secondary to brain
metastasis.

53. 5-year-old female with
headache for 1 year.
FINDINGS
Axial post-contrast T1WI through
the posterior fossa.
- large mass from the L cerebellum,
compressing the BS and effacing 4th
Ventricle.
-a large cyst and a mural nodule
-Smaller cysts and septations + mural
enhancement
Pilocytic astrocytoma
(PA).

54. 48 year old man with
headaches
Findings
-Axial FLAIR and
corresponding T2WI
respectively.
-Sagittal pre- and post-
contrast T1WI through
the mass.
Tectal
Glioma

55. 10 year old male with
headaches
Findings
-Sagittal T1WI:The mass is
within the 4th ventricle.
-Axial T2WI: heterogeneous
with some cystic foci.
-Axial post-contrast T1WI
through the mass.
Ependymoma

56. 35 year old male with
intermittent headaches
Findings
-Axial DWI + ADC map.
-mixed solid cystic mass
occupying the left trigone with
RD in the solid component .
- ADC map shows surrounding
parenchymal finger-like
hyperintensity consistent with
vasogenic edema
-Axial T2WI
-Axial post-contrast T1WI- avid
contrast enhancement of the
solid component
Anaplastic
ependymoma WHO III.

57. 54 year old woman
presenting with headaches
and right facial nerve
weakness.
Findings
-Axial T2WI through the CPA( with
a CSF Cleft).
-Axial 3D volumetric heavily T2WI.
-Axial post-contrast T1WI reveals
a broad-based mass +
homogenous enhancement
-Coronal post-contrast T1WI
confirms the dural-based lesion
along the tentorium cerebelli
CPA Meningioma

58. 41 year old woman wih
occaisional headaches and
visaul problems
FINDINGS
-Coronal post-contrast
T1WI through the sella
turcica.
-Sagittal post-contrast
T1WI
-Axial post-contrast T1WI
through the sella
-Corresponding ADC map
shows that the mass has
low ADC (RD).
Pituitary Macroadenoma

59. 18 Yr old man presenting
with headaches, decreased
visional acuity, and
hypopituitarism.
Findings
-Axial FLAIR
Hyperintense
multicystic lobulated
mass in the SSR.
-Post-contrast sagittal
T1WI.
Craniopharyngioma
(CP).

60. 38-year-old female with
headaches and
hypopituitarism.
FINDINGS
-Sagittal T1WI.
-an intrasellar
mass that is
isointense with the
brain .
-Coronal post-contrast
T1WI-non enh
-Axial T2WI through
the sella (Post mural
nodule).
Rathke cleft cyst.

61. 45-year-old male with
headache and dizziness.
Findings
-Axial T2WI through the P fossa.
There is a mixed cystic and
solid tumor.
-Axial post-contrast T1WI
-solid nodule demonstrates
intense enhancement, but
there is a lack of
enhancement
of the cyst wall.
- Sagittal post-contrast T1WI -
multiple hemangioblastomas
in the posterior fossa, C &T spine,
= VHL syndrome.
Haemangioblastoma

62. Patient 1 (3-year-old male)
Patient 2 (6-year-old male) both
complain of headache and vomiting.
FINDINGS
-Axial post-contrast MR
T1WI through the P fossa.
Intensely lumpy
ventricular mass
surrounded by a thin rim
of CSF.
-Axial post-contrast T1WI
through the lateral
ventricles in a different
patient.
Choroid Plexus Papilloma

63. 12-year-old male
presenting with headache
Findings
-Axial T2WI through the
P fossa at the level of CPAs
-Axial FLAIR through the mass
-ADC image shows high ADC
without RD.
-Axial post contrast T1WI
shows no appreciable
enhancement in the
Lesion
CPA Arachnoid Cyst

64. 61-year-old female with headache,
nausea, and visual complaints. Visual
field examination revealed a partial
left inferior quadrantanopsia.
FINDINGS
-Axial FLAIR
-2 masses with
heterogeneous
intensity in the right parietal +
occipital lobes
with surrounding edema and
mass effect on the right
trigone
-Axial ADC map through
the masses. There is low ADC
in the masses(RD)
-Axial post-contrast T1WI.
Glioblastoma

65. 49-year-old female on follow-
up for lesion
discovered incidentally.
FINDINGS
-Axial T2WI:
There is a smooth,
round rel isointense
mass occupying the
region of foramina of
Monro
-Axial FLAIR.
Homogenous
hyperintense mass
-Coronal post-contrast
T1WI .
Colloid Cyst in the
3rd ventricle

66. 70-year-old female with cough
and shortness of breath. She lost
15kg over the last 3 months.
Findings
-Axial T2WI
Heterogenous hyperintense
mass +finger like
-ADC map
There is low ADC within the
mass consistent with
restricted diffusion
-The mass demonstrates
marked homogeneous
enhancement.
Primary CNS
lymphoma

67. 34-year-old female with sudden onset
of headache and altered mental
status.
FINDINGS
- Mid-sagittal and axial non-
contrast T1WI, respectively,
through the sella
turcica.
-Both levels are bright,
suggesting methemoglobin.
-Axial T2WI through the sella.
-Post-contrast sagittal T1WI
shows no changes.
Pituitary Apoplexy

68. 6-year-old female with
headaches, vomiting, and ataxia
Findings
-Axial T2WI :
mass is isointense to GM with
hyperintense intratumoral cysts
or necrosis.
-Axial post-contrast T1WI:
mild enhancement of the solid
component of the mass
-Axial DWI through the mass.
The mass demonstrates
restricted diffusion .
Medulloblastoma

69. Sagittal T2
(A) shows small pericallosal
Aneurysm .
Axial T2
(B) shows multiple flow voids within
a large arteriovenous malformation in
the left hemisphere
Vascular
malformations,AVM

70. MRI OF INTRACRANIAL LESIONS
• TRAUMA/HAEMORRHAGE

71. AGING BLOOD ON MRI
• I Be
– T1 Isointense
– T2 Bright
– hyperacute < 1day
• IdDy
– T1 Isointense
– T2 Dark
– acute 1 to 3 days
• BiDy
– ​T1 Bright
– T2 Dark
– early subacute 3 to 7 days
• BaBy
– T1 Bright
– T2 Bright
– late subacute 7 to 14-28 days
• Doo Doo
– T1 Dark
– T2 Dark
– chronic >14 to 28 days
• I Bleed
• I Die
• Bleed Die
• Bleed Bleed
• Die Die

72. Left parietal EDH
(A) T1
(B) T2
Hematoma shows high
signal on both images, which is
consistent with extracellular
Methemoglobin.

73. 59 year old male
presenting headaches
Axial T1WI :
bilateral almost symmetrical crescentic
extraaxial hypointense collections—
almost cerebrospinal
(CSF) intensity .
Axial FLAIR :
bilateral extraaxial collections are
hyperintense,
higher than CSF intensity .
Axial T2WI :The collections are
hyperintense (about CSF intensity)
with some effacement of
convexity sulci but no midline shift.
Axial GRE:
There is “blooming” within
the medial membrane of the
predominantly hyperintense
crescentic collections. This may
suggest acute blood product.
Chronic Subdural
Haematoma

74. MRI OF INTRACRANIAL LESIONS
• INFECTION

75. 59-year-old female on chronic
immunosuppression with
mycophenolate mofetil and
tacrolimus for kidney and
pancreas transplant performed 7
months prior was admitted with
decreased LOC.
Findings
-Axial DWI MRI through the
frontal lobes.
-left frontal lobe well-
circumscribed
hyperintense mass consistent
with restricted diffusion.
-Axial FLAIR
-Axial T2WI through the left
frontal lobe mass
Post-contrast coronal T1WI
- There is a thick irregular mural
contrast enhancement.
Nocardiosis brain abscess.

76. 41-year-old female, without significant past
medical history with a 3-day history of
generalized malaise, nausea, headache,
lethargy, and fever.
Findings
-Corresponding axial DWI and ADC
map through the thalami.
There is a left thalamic focal restricted
diffusion with surrounding
small edema consistent with an
abscess.
-Axial DWI through the trigones.
There is bilateral intraventricular
restricted diffusion with fluid-fluid
levels in the
trigones consistent with cellular
debris
-Axial FLAIR through the third
ventricle.
-Post-contrast coronal T1WI.
Left Thalamic Pyogenic abscess with
ventriculitis

77. COMPLICATIONS
• Exposure to magnetic field
– Implant malfunction
– Noise + potential auditory damage
– Local tissue heating (RF coils)
– Attraction of ferromagnetic materials
• IV contrast
– Anaphylaxis
– Nephrogenic systemic fibrosis
– Pregnancy (risk vs benefit)
– Breastfeeding (??)

78. LOCAL CALLENGES
• Availability
• Cost

79. CURRENT TRENDS
• MRI suite
– Intraoperative MRI
• Tumour surgery
Glioma surgery

80. THE FUTURE PERSPECTIVE
• Higher teslage MRIs
• Faster image acquisition
• Advancements in dedicated software

81. CONCLUSION
• With advances in technology, it is possible to
use the various MRI Protocols in a
complementary manner to successfully
screen, diagnose, plan treatment, follow up
patients, and image complications and predict
prognostic outcomes with a lot of certainty in
diverse pathologies.

82. REFERENCES
• Mark S. Greenberg. Handbook of
Neurosurgery(8th Edition). Canada. Thieme.
2016.
• Mattew Omojola,Mauricio
Castillo;Neuroimaging, a teaching file.
• Richard G. Ellenbogen, Saleem I. Abdulrauf.
Principle of neurological surgery(3rd Edition).
Philadelphia, US: Saunders, an imprint of
Elsevier Inc. 2012.

83. • THANK YOU FOR ATTENTION

84. • COMMENTS
• QUESTIONS

85. CONCLUSION
• Though a relatively recent technology, MRI
has assumed a prominent role in modern day
diagnostics, especially in Neurosurgery
• Given its excellent soft tissue definition and its
continuous development, its utility can only
increase in the years ahead.