DR.MANOJ SEERVI, Principals of MRI BRAIN, DEPT OF NEUROSURGERY, SMS MEDICAL COLLEGE,JAIPUR, INDIA

1. PRINCIPLES OF MRI BRAIN
BY : DR. MANOJ SEERVI & DR. SURESH CHOUDHARY
INCHARGE: DR. ACHAL SHARMA
FACUILTY: DR. J S SHEKHAWAT
DR. GAURAV JAIN
DR. NAVNEET AGARWAL

2. HISTORICAL ASPECT
• 1940s –Felix Bloch &E. Purcell: discovered just after world
war II & named Nuclear Magnetic Resonance (noble prize
1952)
• 1973: Paul Lauterbur published the first nuclear magnetic
resonance image and the first cross-sectional image of a living
mouse in January 1974
• 1977 – Mansfield: first image of human anatomy, first echo
planar image
• 1990s - Discovery that MRI can be used to distinguish
oxygenated blood from deoxygenated blood ,it leads to
Functional Magnetic Resonance imaging (fMRI)
• Paul Lauterbur and Peter Mansfield won the Nobel Prize in
Physiology/Medicine (2003) for their pioneering work in
MRI

3. The first Human MRI scan was performed on 3rd july 1977 by Raymond
Damadian, Minkoff and Goldsmith.

4. Describing Radiological Terms
• USG(ultrasonography)- ECHOGENICITY
• CT(Computed tomography) scan- DENSITY
• MRI(magnetic resonance imaging)- INTENSITY
• Hyper- white/ bright
• Hypo- black/ dark

5. MRI is based on the principle of nuclear magnetic resonance
(NMR)
• Two basic principles of NMR
1. Atoms with an odd number of protons have spin
2. A moving electric charge, be it positive or negative,
produces a magnetic field
• Body has many such atoms that can act as good MR nuclei (1H,
13C, 19F, 23Na)
• MRI utilizes this magnetic spin property of protons of
hydrogen to produce images.
• In our natural state Hydrogen ions in body are spinning in a
haphazard fashion, and cancel all the magnetism. When an
external magnetic field is applied protons in the body align in
one direction.
BASIC PRINCIPLES OF MRI

6. Why Hydrogen ions are used in MRI?
1. Hydrogen nucleus has an unpaired proton which
is positively charged
2. Every hydrogen nucleus is a tiny magnet which
produces small but noticeable magnetic field
3. Hydrogen is abundant in the body in the form
of water and fat
4. Essentially all MRI is hydrogen (proton) imaging

7. • TE (Echo Time) : the time between the delivery of the RF
pulse and the receipt of the echo signal
• TR (Repetition Time) : The time between two excitations
is called repetition time.
TR & TE

8. • By varying the TR and TE one can obtain T1WI and T2WI.
• In general a short TR (<1000ms) and short TE (<45 ms) scan
is T1WI.
• Long TR (>2000ms) and long TE (>45ms) scan is T2WI.

9. BASIC MR BRAIN SEQUENCES
• ROUTINE SEQUENCES
– T1 – for anatomy
– T2- for pathological details
– FLAIR – suppress fluid
• SPECIAL SEQUENCES
– DWI – for infarcts, abscess , tumour detection
– ADC – for differentiation of different age of infarcts
– MRA – for arterial details
– MRV – for venous details
– MRS – spectroscopy for chemical compositions of the lesion
– GRE
– FIESTA(FAST IMAGING EMPLOYING STEADY STATE ACQUISITION)
/CISS(CONSTRUCTIVE INTERFERENCE STEADY STATE),
– STIR
– SWI

10. • SHORT TE
• SHORT TR
• BETTER ANATOMICAL DETAILS
• FLUID : DARK/CSF BLACK
• GRAY MATTER : GRAY
• WHITE MATTER: WHITE
T1 W IMAGES

11. • Most of pathologies are DARK/ HYPOINTENSE
on T1
• BRIGHT ON T1
– Fat
– Sub acute H’age (Methaemoglobin)
– Melanin
– High Protein Contents
– Posterior Pituitary appears bright on T1
(Neurosecretory granules)
– Gadolinium contrast
– Cholesterol

12. • LONGTE
• LONG TR
• BETTER PATHOLOGICAL DETAILS
• FLUID: BRIGHT/Hyperintense
• GRAY MATTER : RELATIVELY BRIGHT
• WHITE MATTER: DARK
T2 W IMAGES

13. T1 W IMAGES

14. T1W AND T2 W IMAGES

15. • LONG TE
• LONG TR
• SIMILAR TO T2 EXCEPT FREE WATER SUPRESSION
(INVERSION RECOVERY)
• CSF : DARK
• GRAY MATTER : RELATIVELY BRIGHT
• WHITE MATTER: DARK
• Most pathology is BRIGHT
• Hydrocephalous: Periventricular hyperintensity(CSF
ooze)
• Especially good for lesions near ventricles or sulci or
CSF containing spaces (eg Multilpe Sclerosis)
FLAIR (Fluid Attenuated Inversion Recovery Sequences)
Same as T2
with CSF
suppression

16. CT
FLAIR
T2
T1

18. Multiple sclerosis:
periventricular
demyelinating process
(white arrows) and
white matter
inflammatory changes
around the
perimedullary veins,
known as Dawson
Fingers (red arrows)

19. Clinical Applications of FLAIR sequences:
• Used to evaluate diseases affecting the brain parenchyma neighboring
the CSF-containing spaces for
eg: MS & other demyelinating disorders.
• Unfortunately, less sensitive for lesions involving the brainstem &
cerebellum, owing to CSF pulsation artifacts
• Mesial temporal sclerosis (MTS) (thin section coronal FLAIR)
• Tuberous Sclerosis – for detection of Hamartomatous lesions.
• Helpful in evaluation of neonates with perinatal HIE.

20. T1W T2W FLAIR(T2)
TR SHORT LONG LONG
TE SHORT LONG LONG
CSF LOW HIGH LOW
FAT HIGH HIGH MEDIUM
GREY MATTER LOW HIGH HIGH
WHITE MATTER HIGH LOW LOW
EDEMA LOW HIGH HIGH

21. GRADATION OF INTENSITY
IMAGING
CT SCAN CSF Edema White
Matter
Gray
Matter
Blood Bone
MRI T1 CSF Edema Gray
Matter
White
Matter
Cartilage Fat
MRI T2 Cartilage Fat White
Matter
Gray
Matter
Edema CSF
MRI T2 Flair CSF Cartilage Fat White
Matter
Gray
Matter
Edema

22. MRI BRAIN :AXIAL SECTIONS

47. MRI BRAIN :SAGITTAL SECTIONS

48. White Matter
Cerebellum
Parietal Lobe
Frontal Lobe
Lateral Sulcus
Grey Matter
Occipital Lobe
Temporal Lobe

49. Gyri of cerebral
cortex
Sulci of cerebral
Cortex
Cerebellum
Frontal Lobe
Temporal
Lobe

50. Frontal Lobe
Temporal
Lobe
Parietal Lobe
Occipital
Lobe
Cerebellum

51. Frontal Lobe
Parietal Lobe
Orbit
Occipital Lobe
Transverse sinus
Cerebellar
Hemisphere

52. Optic Nerve
Precentral Sulcus
Lateral Ventricle
Occipital Lobe
Maxillary sinus

53. Caudate
Nucleus
Corpus callosum
Thalamus
Tongue
Tentorium
Cerebell
Pons

54. Splenium of
Corpus callosum
Pons
Ethmoid air
Cells
Inferior nasal
Concha
Midbrain
Fourth Ventricle
Genu of Corpus
Callosum
Hypophysis
Thalamus

55. Splenium of
Corpus
callosum
Genu of corpus
callosum
Pons
Superior
Colliculus
Inferior
Colliculus
Nasal Septuml
Medulla
Body of corpus
callosum
Thalamus

56. Cingulate Gyrus
Genu of corpus
callosum
Ethmoid
air cells
Oral cavity
Splenium of
Corpus
callosum
Fourth Ventricle

57. Frontal
Lobe
Maxillary
Sinus
Parietal Lobe
Occipital Lobe
Corpus Callosum
Thalamus
Cerebellum

58. Frontal Lobe
Temporal
Lobe
Parietal Lobe
Lateral Ventricle
Occipital Lobe
Cerebellum

59. Frontal Lobe
Parietal Lobe
Superior Temporal
Gyrus
Lateral Sulcus
Inferior Temporal
Gyrus
Middle Temporal Gyrus
External Auditory
Meatus

60. . Bone
Inferior sagittal sinus
Corpus callosum
Internal cerebral vein
Superior sagittal sinus
Parietal lobe
Vein of Galen
Occipital lobe
Straight sinus
. Vermis
. IV ventricle
Cerebellar tonsil
Mass intermedia
of thalamus
Sphenoid Sinus

61. MRI BRAIN :CORONAL SECTIONS

62. Longitudinal
Fissure
Straight Sinus
Superior Sagittal Sinus
Sigmoid Sinus
Vermis

63. Arachnoid Villi
Great Cerebral
Vein
Tentorium
Cerebelli
Falx Cerebri
Lateral Ventricle
Vermis of
Cerebellum
Cerebellum

64. Splenium of
Corpus callosum
Posterior
Cerebral
Artery
Superior
Cerebellar
Artery
Foramen
Magnum
Lateral Ventricle
Internal Cerebral
Vein
Tentorium
Cerebelli
Fourth Ventricle

65. Cingulate Gyrus
Choroid Plexus
Superior Colliculus
Cerebral Aqueduct
Corpus Callosum
Thalamus
Pineal Gland
Vertebral Artery

66. Insula
Lateral Sulcus
Cerebral Peduncle
Olive
Crus of Fornix
Middle Cerebellar
Peduncle

67. Caudate Nucleus
Third Ventricle
Hippocampus
Pons
Corpus Callosum
Thalamus
Cerebral
Peduncle
Parahippocampal
gyrus

68. Lateral Ventricle
Temporal Horn of
Lateral Ventricle
Uncus of Temporal
Lobe
Body of Fornix
Third Ventricle
Hippocampus

69. Internal Capsule
Caudate Nucleus
Optic Tract
Insula
Parotid Gland
Amygdala
Lentiform
Nucleus
Hypothalamus

70. Internal Capsule
Cingulate Gyrus
Optic Nerve
Nasopharynx
Caudate
Nucleusa
Lentiform
Nucleus
Internal
Carottid Artery

71. Longitudinal
Fissure
Superior Sagittal
Sinus
Lateral Sulcus
Parotid Gland
Genu Of
Corpus
Callosum
Temporal Lobe

72. Frontal Lobe
Nasal
Turbinate
Massetor
Ethmoid Sinus
Nasal Septum
Nasal Cavity
Tongue

73. Frontal Lobe
Medial Rectus
Lateral Rectus
Inferior Turbinate
Superior Rectus
Inferior Rectus
Maxillary Sinus
Tooth

74. Grey Matter
Superior Sagittal Sinus
White Matter
Eye Ball
Maxillary Sinus
Tongue

75. Coronal Section of the Brain at the level of Pituitary gland
Post Contrast Coronal T1 Weighted MRI
sp
np
Frontal lobe
Corpus callosum
Frontal horn
III
Pituitary stalk
Pituitary gland Caudate nucleus
Optic nerve
Internal carotid artery
Cavernous sinus

76. CENTRAL SULCUS
•Upper T sign : the superior frontal sulcus intersects the precentral sulcus in a
"T" junction. The central sulcus is the next posterior sulcus.
•L sign: the superior frontal gyrus intersects precentral gyrus in an "L"
junction. The central sulcus is immediately posterior.
•Lower T sign: the inferior frontal sulcus terminates posteriorly in the
precentral sulcus in a "T" junction. The central sulcus is the next posterior
sulcus.
•M sign: the inferior frontal gyrus has a characteristic "M" configuration and
terminates posteriorly in the precentral gyrus. The central sulcus is
immediately posterior.

82.  Bracket sign: the marginal sulcus is visible immediately posterior to the
central sulcus, and is easily identifiable of sagittal paramedian images as the
continuation of the cingulate sulcus
sigmoidal hook (handknob, omega) sign: the precentral gyrus bulges
posteriorly at the hand motor area
bifid postcentral gyrus sign: the postcentral gyrus is split medially by the pars
marginalis of the cingulate sulcus
 U sign: the most inferolateral extent of the central sulcus is capped by a U-
shaped gyrus – the subcentral gyrus – which abuts the lateral fissure

83. • Free water diffusion in the images is Dark (Normal)
• Acute stroke, cytotoxic edema causes decreased rate of water
diffusion within the tissue i.e. Restricted Diffusion (due to
inactivation of Na K Pump )
• Increased intracellular water causes cell swelling
• Areas of restricted diffusion are BRIGHT.
• Restricted diffusion occurs in
– Cytotoxic edema
– Ischemia (within minutes)
– Abscess
DIFFUSION WEIGHTED IMAGES (DWI)

84. Other Causes of Positive DWI
• Bacterial abscess, Epidermoid ,Acute demyelination,
Acute Encephalitis, CJD(Creutzfeldt-Jakob disease)
• T2 shine through ( High ADC)
• To confirm true restricted diffusion - compare the DWI image
to the ADC.
• In cases of true restricted diffusion, the region of
increased DWI signal will demonstrate low signal on
ADC.
• In contrast, in cases of T2 shine-through, the ADC will be
normal or high signal.

85. • Calculated by the software.
• Areas of restricted diffusion are dark
• Negative of DWI
– i.e. Restricted diffusion is bright on DWI,
dark on ADC
NON-ISCHEMIC CAUSES of low ADC :
• Abscess
• Lymphoma and other tumors
• Multiple sclerosis
• Seizures
• Metabolic (Canavans Disease)
APPARENT DIFFUSION COEFFICIENT Sequences
(ADC MAP)

87. • TheADC may be useful for estimating the lesion age and
distinguishing acute from subacute DWI lesions.
• Acute ischemic lesions can be divided into Hyperacute
lesions (lowADC and DWI-positive) and Subacute
lesions (normalizedADC, T2 shine through effect).
• Chronic lesions can be differentiated from acute lesions by
normalization ofADC and DWI.

88. ADC Sequence
65 year male-Acute Rt ACA Infarct
DWI Sequence

89. STIR: Short T1 (Short Tau) inversion recovery
sequence
• In STIR sequences, an inversion-recovery pulse is used to
null the signal from fat (180° RF Pulse).
• STIR sequences provide excellent depiction of bone
marrow edema which may be the only indication of an
occult fracture.

90. • STIR images are highly water-sensitive and the timing of the
pulse sequence used acts to suppress signal coming from fatty
tissues – so ONLY WATER is bright
• A combination of standard T1 images and STIR images can
be compared to determine the amount of fat or water within a
body part
• Abnormal low signal on the T1 image and abnormal high
signal on the STIR image – indicates abnormal fluid

91. • TWO TYPES OF MR ANGIOGRAPHY
– CE (contrast-enhanced) MRA
– Non-Contrast Enhanced MRA
• TOF (time-of-flight) MRA
• PC (phase contrast) MRA
MR ANGIOGRAPHY

92. CE (CONTRAST ENHANCED) MRA
 T1-shortening agent, Gadolinium, injected iv as contrast
 Gadolinium reduces T1 relaxation time
 When TR<<T1, minimal signal from background tissues
 Result is increased signal from Gd containing structures
 Faster gradients allow imaging in a single breathhold
 CAN BE USED FOR MRA, MRV
 FASTER (WITHIN SECONDS)

93. TOF (TIME OF FLIGHT) MRA
 These techniques derive contrast between stationary
tissues and flowing blood by manipulating the magnitude
of the magnetization
 The magnitude of magnetization from the moving spins is
very large as compared to the magnetization from the
stationary spins which are relatively small. This leads to a
large signal from moving blood spins and a diminished
signal from stationary tissue spins. Blood vessels usually
appear bright on TOF image
 2D TOF- SENSITIVE TO SLOW FLOW – VENOGRAPHY
 3D TOF- SENSITIVE TO HIGH FLOW – MR ANGIOGRAPHY

94. PHASE CONTRAST (PC) MRA
• It derive contrast between stationary tissues and flowing blood by
manipulating the phase of the magnetization.
• The phase of the magnetization from the stationary spins is zero and the phase
of the magnetization from the moving spins is non-zero.
• In phase difference images, the signal is linearly proportional to the velocity
of the spins. Fast moving spins give rise to a larger signal and spins moving in
one direction are assigned a bright signal and appear white in the scan ,
• whereas spins moving in the opposite direction are assigned a dark signal and
appear black on the scan.

95. Vertebral Artery
Middle Cerebral
Artery
Internal Carotid
Artery
Basilar Artery
Anterior Cerebral
Artery
Posterior Cerebral
Artery
Posterior Inferior
Cerebellar Artery
Superior
Cerebellar Artery
Anterior Inferior
Cerebellar Artery

96. Vertebral Artery
Posterior Cerebral
Artery
Anterior Cerebral
Artery
Middle Cerebral
Artery
Internal Carotid
Artery
Basilar Artery

97. MR VENOGRAPHY

101. Oblique view

102. • Form of T2-weighted image which is susceptible
to iron, calcium or blood.
• Blood, bone, calcium appear dark
• Areas of blood often appears much larger than
reality (BLOOMING)
• Useful for:
– Identification of haemorrhage / calcification
Look for: DARK only
GRE Sequences (GRADIENT RECALLED
ECHO/T2 *)

104.  Perfusion is the process of nutritive delivery of arterial
blood to a capillary bed in the biological tissue
means that the tissue is not getting
enough blood with oxygen and nutritive elements
(ischemia)
means neoangiogenesis – increased
capillary formation (e.g. tumor activity)
PERFUSION STUDIES

105. ⚫ Stroke
Detection and
assessment of
ischemic stroke
(Lower perfusion )
 Tumors
Diagnosis, staging, assessment of
tumour grade and prognosis
Treatment response
Post treatment evaluation
Prognosis of therapy effectiveness
(Higher perfusion)
APPLICATIONS OF PERFUSION IMAGING

106. CISS OR FIESTA
• FIESTA (Fast Imaging Employing Steady-state
Acquisition) is the GE name for a balanced steady-state
gradient echo sequence. Philips calls balanced-FFE
(Fast Field Echo). The equivalent Siemens product is
called CISS (Constructive Interference Steady State).
• CISS sequence uses a strong T2-weighted 3D gradient echo
technique which produces high resolution isotropic images.
• Two consecutive runs of 3D balanced steady-state free
precession with different excitation levels are performed
internally and subsequently combined. Image contrast in CISS is
determined by the T2/T1 ratio of the tissue.

107. • Tissues with both long T2 and short T1 relaxation
times have high signal intensity on CISS images.
• Due to high T2/T1 ratio, water and fat have high
signal on this sequence.
• The CISS sequence provides excellent contrast
between cerebrospinal fluid (CSF) and other
structures in the brain.
• For these reasons, CISS sequence is very useful for
evaluating structures surrounded by CSF (e.g.
cranial nerves).

108. CN I

110. CN II

111. CN III

112. CN IV

113. CN V

114. CN V

115. CN V

116. CN V

117. Trigeminal neuralgia

118. CN VI

119. CN VII

120. CN VII

121. CN VIII

122. CN VIII

123. CN IX

124. CN X

125. CN XI

126. CN XII

127. Cisterns

128. Cisterns

133. Oculomotor cistern

134. THANK YOU