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NORMAL MRI BRAIN
DR. PIYUSH OJHA
DM RESIDENT
DEPARTMENT OF NEUROLOGY
GOVT MEDICAL COLLEGE, KOTA
History: MRI
• Paul Lauterbur and Peter Mansfield won the Nobel
Prize in Physiology/Medicine (2003) for their
pioneering w...
The first Human MRI scan was performed on 3rd july 1977 by Raymond
Damadian, Minkoff and Goldsmith.
MAGNETIC FIELD STRENGTH
• S.I. unit of Magnetic Field is Tesla.
• Old unit was Gauss.
• 1 Tesla = 10,000 Gauss
• Earth’s M...
• MRI is based on the principle of nuclear magnetic
resonance (NMR)
• Two basic principles of NMR
1. Atoms with an odd num...
• Hydrogen nucleus has an unpaired proton which is
positively charged
• Hydrogen atom is the only major element in the bod...
• TE (echo time) : time interval in which signals are
measured after RF excitation
• TR (repetition time) : the time betwe...
BASIC MR BRAIN SEQUENCES
• T1
• T2
• FLAIR
• DWI
• ADP
• MRA
• MRV
• MRS
• SHORT TE
• SHORT TR
• BETTER ANATOMICAL DETAILS
• FLUID DARK
• GRAY MATTER GRAY
• WHITE MATTER WHITE
T1 W IMAGES
• MOST PATHOLOGIES DARK ON T1
• BRIGHT ON T1
– Fat
– Haemorrhage
– Melanin
– Early Calcification
– Protein Contents (Collo...
T1 W IMAGES
• LONG TE
• LONG TR
• BETTER PATHOLOGICAL DETAILS
• FLUID BRIGHT
• GRAY MATTER RELATIVELY BRIGHT
• WHITE MATTER DARK
T2 W ...
T1W AND T2 W IMAGES
• LONG TE
• LONG TR
• SIMILAR TO T2 EXCEPT FREE WATER SUPRESSION
(INVERSION RECOVERY)
• Most pathology is BRIGHT
• Especia...
CT
FLAIRT2
T1
T1W T2W FLAIR(T2)
TR SHORT LONG LONG
TE SHORT LONG LONG
CSF LOW HIGH LOW
FAT HIGH LOW MEDIUM
BRAIN LOW HIGH HIGH
EDEMA LOW...
MRI BRAIN :AXIAL SECTIONS
Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Weighted
M.R.I.
Section at the level of Foramen
Magnum...
Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of medulla
Sigmoid Sin...
ICA
Temporal
lobe
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Pons
Cerebellar
Hemisphere
Vermis
IV Ventri...
Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Mid Brain
Aqueduct ...
Fig. 1.5 Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of theIII Ven...
Fig. 1.6 Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Thalamus
S...
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Corpus
Callosum
Genu of corpus callosum
Splenium of corpus ca...
Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section at the level of Body of
Corpus Call...
Post Contrast Axial MR Image of the brain
Post Contrast sagittal T1 Wtd
M.R.I.
Section above the Corpus Callosum
Parietal ...
MRI BRAIN :SAGITTAL SECTIONS
Grey Matter
White Matter
White Matter
Cerebellum
Grey Matter
Frontal Lobe
Parietal Lobe
Temporal Lobe
Lateral Sulcus Occipital Lobe
Gyri of cerebral
cortex
Sulci of cerebral
Cortex
Cerebellum
Frontal Lobe
Temporal
Lobe
Frontal Lobe
Temporal
Lobe
Parietal Lobe
Occipital
Lobe
Cerebellum
Frontal Lobe
Parietal Lobe
Orbit
Occipital Lobe
Transverse sinus
Cerebellar
Hemisphere
Optic Nerve
Precentral Sulcus
Lateral Ventricle
Occipital Lobe
Maxillary sinus
Caudate
Nucleus
Corpus callosum
Thalamus
Tongue
Pons
Tentorium
Cerebell
Splenium of
Corpus callosum
Pons
Ethmoid air
Cells
Inferior nasal
Concha
Midbrain
Fourth Ventricle
Genu of Corpus
Callosum...
Splenium of
Corpus
callosumGenu of corpus
callosum
Pons
Superior
Colliculus
Inferior
Colliculus
NasalNasal Septuml
Medulla...
Cingulate Gyrus
Genu of corpus
callosum
Ethmoid
air cells
Oral cavity
Splenium of
Corpus
callosum
Fourth Ventricle
Frontal
Lobe
Maxillary
Sinus
Parietal Lobe
Occipital Lobe
Corpus Callosum
Thalamus
Cerebellum
Frontal Lobe
Temporal
Lobe
Parietal Lobe
Lateral Ventricle
Occipital Lobe
Cerebellum
Frontal Lobe
Parietal Lobe
Superior Temporal
Gyrus
Lateral Sulcus
Inferior Temporal
Gyrus
Middle Temporal Gyrus
External A...
. Bone
Inferior sagittal sinus
Corpus callosum
Internal cerebral vein
Vein of Galen
Superior sagittal sinus
Parietal lobe
...
MRI BRAIN :CORONAL SECTIONS
Longitudinal
Fissure
Straight Sinus
Superior Sagittal Sinus
Sigmoid Sinus
Vermis
Straight Sinus
Cerebellum
Lateral Ventricle,
Occipital Horn
Arachnoid Villi
Great Cerebral
Vein
Tentorium
Cerebelli
Falx Cerebri
Lateral Ventricle
Vermis of
Cerebellum
Cerebellum
Splenium of
Corpus callosum
Posterior
Cerebral
Artery
Superior
Cerebellar
Artery
Foramen
Magnum
Lateral Ventricle
Internal...
Cingulate Gyrus
Choroid Plexus
Superior Colliculus
Cerebral Aqueduct
Corpus Callosum
Thalamus
Pineal Gland
Vertebral Artery
Insula
Lateral Sulcus
Cerebral Peduncle
Olive
Crus of Fornix
Middle Cerebellar
Peduncle
Caudate Nucleus
Third Ventricle
Hippocampus
Pons
Corpus Callosum
Thalamus
Cerebral
Peduncle
Parahippocampal
gyrus
Lateral Ventricle
Body of Fornix
Temporal Horn of
Lateral Ventricle
Uncus of Temporal
Lobe
Third Ventricle
Hippocampus
Internal Capsule
Caudate Nucleus
Optic Tract
Insula
Lentiform
Nucleus
Parotid Gland
Amygdala
Hypothalamus
Internal Capsule
Cingulate Gyrus
Optic Nerve
Nasopharynx
Internal
Carottid Artery
Lentiform
Nucleus
Caudate
Nucleusa
Longitudinal
Fissure
Superior Sagittal
Sinus
Lateral Sulcus
Parotid Gland
Genu Of
Corpus
Callosum
Temporal Lobe
Ethmoid Sinus
Frontal Lobe
Nasal
Turbinate
Massetor
Nasal Septum
Nasal Cavity
Tongue
Medial Rectus
Frontal Lobe
Lateral Rectus
Inferior Turbinate
Superior Rectus
Inferior Rectus
Maxillary Sinus
Tooth
Grey Matter
Superior Sagittal Sinus
White Matter
Eye Ball
Maxillary Sinus
Tongue
Coronal Section of the Brain at the level of Pituitary gland
Post Contrast Coronal T1 Weighted MRI
sp
np
Frontal lobe
Corp...
FLAIR & STIR SEQUENCES
Short TI inversion-recovery (STIR) sequence
• In STIR sequences, an inversion-recovery pulse is used to
null the signal fr...
Comparison of fast SE and STIR sequences
for depiction of bone marrow edema
FSE STIR
Fluid-attenuated inversion recovery
(FLAIR)
• First described in 1992 and has become one of the corner stones of
brain MR ...
• Most pathologic processes show increased SI on T2-WI,
and the conspicuity of lesions that are located close to
interface...
Clinical Applications of FLAIR sequences:
• Used to evaluate diseases affecting the brain parenchyma neighboring
the CSF-c...
• Embolic infarcts- Improved visualization
• Chronic infarctions- typically dark with a rim of high
signal. Bright periphe...
T2 W
FLAIR
T1 W Images:
Subacute Hemorrhage
Fat-containing structures
Anatomical Details
T2 W Images:
Edema
Tumor
Infarction
Hemorrha...
• Free water diffusion in the images is Dark
(Normal)
• Acute stroke, cytotoxic edema causes
decreased rate of water diffu...
• Areas of restricted diffusion are
BRIGHT.
• Restricted diffusion occurs in
– Cytotoxic edema
– Ischemia (within minutes)...
Other Causes of Positive DWI
• Bacterial abscess, Epidermoid Tumor
• Acute demyelination
• Acute Encephalitis
• CJD
• T2 s...
T2 SHINE THROUGH
• Refers to high signal on DWI images that is not
due to restricted diffusion, but rather to high T2
sign...
• To confirm true restricted diffusion - compare
the DWI image to the ADC.
• In cases of true restricted diffusion, the
re...
• Calculated by the software.
• Areas of restricted diffusion are dark
• Negative of DWI
– i.e. Restricted diffusion is br...
• The ADC may be useful for estimating the lesion age
and distinguishing acute from subacute DWI lesions.
• Acute ischemic...
Nonischemic causes for decreased ADC
• Abscess
• Lymphoma and other tumors
• Multiple sclerosis
• Seizures
• Metabolic (Ca...
65 year male-Acute Rt ACA Infarct
DWI Sequence ADC Sequence
Clinical Uses of DWI & ADC in Ischemic Stroke
• Hyperacute Stage:- within one hour minimal hyperintensity seen in
DWI and ...
• Post contrast images are always T1 W images
• Sensitive to presence of vascular or extravascular Gd
• Useful for visuali...
MR ANGIOGRAPHY / VENOGRAPHY
• TWO TYPES OF MR ANGIOGRAPHY
– CE (contrast-enhanced) MRA
– Non-Contrast Enhanced MRA
• TOF (time-of-flight) MRA
• PC (ph...
CE (CONTRAST ENHANCED) MRA
 T1-shortening agent, Gadolinium, injected iv as contrast
 Gadolinium reduces T1 relaxation t...
TOF (TIME OF FLIGHT) MRA
 Signal from movement of unsaturated blood converted into
image
 No contrast agent injected
 M...
PHASE CONTRAST (PC) MRA
 Phase shifts in moving spins (i.e. blood) are measured
 Phase is proportional to velocity
 All...
Internal Carotid
Artery
Basilar Artery
Vertebral Artery
Middle Cerebral
Artery
Anterior Cerebral
Artery
Posterior Cerebral...
Vertebral Artery
Basilar Artery
Posterior Cerebral
Artery
Internal Carotid
Artery
Anterior Cerebral
Artery
Middle Cerebral...
MR VENOGRAPHY
NORMAL MR VENOGRAPHY (Lateral View)
Superior
Sagittal Sinus
Internal
Jugular Vein
Sigmoid Sinus
Transverse Sinus
Confluenc...
NORMAL MR VENOGRAPHY (Lateral View)
• Form of T2-weighted image which is susceptible
to iron, calcium or blood.
• Blood, bone, calcium appear dark
• Areas of ...
• Non-invasive physiologic imaging of brain that
measures relative levels of various tissue
metabolites.
• Used to complem...
Observable metabolites
Metabolite Resonating
Location
ppm
Normal function Increased
Lipids 0.9 & 1.3 Cell membrane
compone...
Metabolite Location
ppm
Normal function Increased Decreased
NAA 2 Nonspecific
neuronal marker
(Reference for
chemical shif...
Metabolite Location
ppm
Normal
function
Increased Decreased
Choline 3.2 Marker of cell
memb turnover
Neoplasia,
demyelinat...
Metabolite ratios:
Normal abnormal
NAA/ Cr 2.0 <1.6
NAA/ Cho 1.6 <1.2
Cho/Cr 1.2 >1.5
Cho/NAA 0.8 >0.9
Myo/NAA 0.5 >0.8
MRS
Dec NAA/Cr
Inc acetate,
succinate, amino
acid, lactate
Neuodegenerat
ive
Alzheimer
Dec NAA/Cr
Dec NAA/
Cho
Inc
Myo/NAA...
• ICSOLs
• Differentiate Neoplasms from Nonneoplastic
Brain Masses
• Radiation Necrosis versus Recurrent Tumor
• Inborn Er...
 Perfusion is the process of nutritive delivery of arterial
blood to a capillary bed in the biological tissue
means that ...
 Stroke
Detection and
assessment of
ischemic stroke
(Lower perfusion )
 Tumors
Diagnosis, staging, assessment of
tumour ...
REFERENCES
• CT and MRI of the whole body – John R Haaga (5th
edition)
• Osborne Brain : Imaging, Pathology and Anatomy
• ...
THANK YOU
• CISS / 3D FIESTA SEQUENCE
• Heavily T2 Wtd Sequences
• Allows much higher resolution and clearer
imaging of tiny intracr...
MAGNETIZATION TRANSFER (MT) MRI
• MT is a recently developed MR technique that alters contrast
of tissue on the basis of m...
GRADATION OF INTENSITY
IMAGING
CT SCAN CSF Edema White
Matter
Gray
Matter
Blood Bone
MRI T1 CSF Edema Gray
Matter
White
Ma...
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
Normal mri brain
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Normal mri brain

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By Dr Piyush Ojha , DM Resident, GMC Kota
under guidance of Prof. Dr Vijay Sardana (HOD,Neurology)

Published in: Health & Medicine
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Normal mri brain

  1. 1. NORMAL MRI BRAIN DR. PIYUSH OJHA DM RESIDENT DEPARTMENT OF NEUROLOGY GOVT MEDICAL COLLEGE, KOTA
  2. 2. History: MRI • Paul Lauterbur and Peter Mansfield won the Nobel Prize in Physiology/Medicine (2003) for their pioneering work in MRI • 1940s – Bloch & Purcell: Nuclear Magnetic Resonance (Nobel Prize in 1952) • 1990s - Discovery that MRI can be used to distinguish oxygenated blood from deoxygenated blood. Leads to Functional Magnetic Resonance imaging (fMRI) • 1973 - Lauterbur: gradients for spatial localization of images (ZEUGMATOGRAPHY) • 1977 – Mansfield: first image of human anatomy, first echo planar image
  3. 3. The first Human MRI scan was performed on 3rd july 1977 by Raymond Damadian, Minkoff and Goldsmith.
  4. 4. MAGNETIC FIELD STRENGTH • S.I. unit of Magnetic Field is Tesla. • Old unit was Gauss. • 1 Tesla = 10,000 Gauss • Earth’s Magnetic Field ~ 0.7 x 10(-4) Tesla • Refrigerator Magnet ~ 5 x 10(-3) Tesla
  5. 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. MRI
  6. 6. • Hydrogen nucleus has an unpaired proton which is positively charged • Hydrogen atom is the only major element in the body that is MR sensitive. • Hydrogen is abundant in the body in the form of water and fat • Essentially all MRI is hydrogen (proton 1H) imaging
  7. 7. • TE (echo time) : time interval in which signals are measured after RF excitation • TR (repetition time) : the time between two excitations is called repetition time. • 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. TR & TE
  8. 8. BASIC MR BRAIN SEQUENCES • T1 • T2 • FLAIR • DWI • ADP • MRA • MRV • MRS
  9. 9. • SHORT TE • SHORT TR • BETTER ANATOMICAL DETAILS • FLUID DARK • GRAY MATTER GRAY • WHITE MATTER WHITE T1 W IMAGES
  10. 10. • MOST PATHOLOGIES DARK ON T1 • BRIGHT ON T1 – Fat – Haemorrhage – Melanin – Early Calcification – Protein Contents (Colloid cyst/ Rathke cyst) – Posterior Pituitary appears BRIGHT ON T1 – Gadolinium
  11. 11. T1 W IMAGES
  12. 12. • LONG TE • LONG TR • BETTER PATHOLOGICAL DETAILS • FLUID BRIGHT • GRAY MATTER RELATIVELY BRIGHT • WHITE MATTER DARK T2 W IMAGES
  13. 13. T1W AND T2 W IMAGES
  14. 14. • LONG TE • LONG TR • SIMILAR TO T2 EXCEPT FREE WATER SUPRESSION (INVERSION RECOVERY) • Most pathology is BRIGHT • Especially good for lesions near ventricles or sulci (eg Multilpe Sclerosis) FLAIR – Fluid Attenuated Inversion Recovery Sequences
  15. 15. CT FLAIRT2 T1
  16. 16. T1W T2W FLAIR(T2) TR SHORT LONG LONG TE SHORT LONG LONG CSF LOW HIGH LOW FAT HIGH LOW MEDIUM BRAIN LOW HIGH HIGH EDEMA LOW HIGH HIGH
  17. 17. MRI BRAIN :AXIAL SECTIONS
  18. 18. Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Weighted M.R.I. Section at the level of Foramen Magnum Cisterna Magna . Cervical Cord . Nasopharynx . Mandible . Maxillary Sinus
  19. 19. Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section at the level of medulla Sigmoid Sinus Medulla Internal Jugular Vein Cerebellar Tonsil Orbits
  20. 20. ICA Temporal lobe Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Pons Cerebellar Hemisphere Vermis IV Ventricle Pons Basilar Artery Cavernous Sinus MCP IAC Mastoid Sinus
  21. 21. Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Mid Brain Aqueduct of Sylvius Orbits Posterior Cerebral ArteryMiddle Cerebral Artery Midbrain Frontal Lobe Temporal Lobe Occipital Lobe
  22. 22. Fig. 1.5 Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section at the level of theIII Ventricle Occipital Lobe III Ventricle Frontal lobe Temporal Lobe Sylvian Fissure
  23. 23. Fig. 1.6 Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Thalamus Superior Sagittal Sinus Occipital Lobe Choroid Plexus . Internal Cerebral Vein Frontal Horn Thalamus Temp Lobe Internal Capsule . Putamen Caudate Nucleus Frontal Lobe
  24. 24. Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Corpus Callosum Genu of corpus callosum Splenium of corpus callosum Choroid plexus within the body of lateral ventricle
  25. 25. Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Body of Corpus Callosum Parietal Lobe Body of the Corpus Callosum Frontal Lobe
  26. 26. Post Contrast Axial MR Image of the brain Post Contrast sagittal T1 Wtd M.R.I. Section above the Corpus Callosum Parietal Lobe Frontal Lobe
  27. 27. MRI BRAIN :SAGITTAL SECTIONS
  28. 28. Grey Matter White Matter
  29. 29. White Matter Cerebellum Grey Matter Frontal Lobe Parietal Lobe Temporal Lobe Lateral Sulcus Occipital Lobe
  30. 30. Gyri of cerebral cortex Sulci of cerebral Cortex Cerebellum Frontal Lobe Temporal Lobe
  31. 31. Frontal Lobe Temporal Lobe Parietal Lobe Occipital Lobe Cerebellum
  32. 32. Frontal Lobe Parietal Lobe Orbit Occipital Lobe Transverse sinus Cerebellar Hemisphere
  33. 33. Optic Nerve Precentral Sulcus Lateral Ventricle Occipital Lobe Maxillary sinus
  34. 34. Caudate Nucleus Corpus callosum Thalamus Tongue Pons Tentorium Cerebell
  35. 35. Splenium of Corpus callosum Pons Ethmoid air Cells Inferior nasal Concha Midbrain Fourth Ventricle Genu of Corpus Callosum Hypophysis Thalamus
  36. 36. Splenium of Corpus callosumGenu of corpus callosum Pons Superior Colliculus Inferior Colliculus NasalNasal Septuml Medulla Body of corpus callosum Thalamus
  37. 37. Cingulate Gyrus Genu of corpus callosum Ethmoid air cells Oral cavity Splenium of Corpus callosum Fourth Ventricle
  38. 38. Frontal Lobe Maxillary Sinus Parietal Lobe Occipital Lobe Corpus Callosum Thalamus Cerebellum
  39. 39. Frontal Lobe Temporal Lobe Parietal Lobe Lateral Ventricle Occipital Lobe Cerebellum
  40. 40. Frontal Lobe Parietal Lobe Superior Temporal Gyrus Lateral Sulcus Inferior Temporal Gyrus Middle Temporal Gyrus External Auditory Meatus
  41. 41. . Bone Inferior sagittal sinus Corpus callosum Internal cerebral vein Vein of Galen Superior sagittal sinus Parietal lobe Occipital lobe Straight sinus . Vermis . IV ventricle Cerebellar tonsil Mass intermedia of thalamus Sphenoid Sinus
  42. 42. MRI BRAIN :CORONAL SECTIONS
  43. 43. Longitudinal Fissure Straight Sinus Superior Sagittal Sinus Sigmoid Sinus Vermis
  44. 44. Straight Sinus Cerebellum Lateral Ventricle, Occipital Horn
  45. 45. Arachnoid Villi Great Cerebral Vein Tentorium Cerebelli Falx Cerebri Lateral Ventricle Vermis of Cerebellum Cerebellum
  46. 46. Splenium of Corpus callosum Posterior Cerebral Artery Superior Cerebellar Artery Foramen Magnum Lateral Ventricle Internal Cerebral Vein Tentorium Cerebelli Fourth Ventricle
  47. 47. Cingulate Gyrus Choroid Plexus Superior Colliculus Cerebral Aqueduct Corpus Callosum Thalamus Pineal Gland Vertebral Artery
  48. 48. Insula Lateral Sulcus Cerebral Peduncle Olive Crus of Fornix Middle Cerebellar Peduncle
  49. 49. Caudate Nucleus Third Ventricle Hippocampus Pons Corpus Callosum Thalamus Cerebral Peduncle Parahippocampal gyrus
  50. 50. Lateral Ventricle Body of Fornix Temporal Horn of Lateral Ventricle Uncus of Temporal Lobe Third Ventricle Hippocampus
  51. 51. Internal Capsule Caudate Nucleus Optic Tract Insula Lentiform Nucleus Parotid Gland Amygdala Hypothalamus
  52. 52. Internal Capsule Cingulate Gyrus Optic Nerve Nasopharynx Internal Carottid Artery Lentiform Nucleus Caudate Nucleusa
  53. 53. Longitudinal Fissure Superior Sagittal Sinus Lateral Sulcus Parotid Gland Genu Of Corpus Callosum Temporal Lobe
  54. 54. Ethmoid Sinus Frontal Lobe Nasal Turbinate Massetor Nasal Septum Nasal Cavity Tongue
  55. 55. Medial Rectus Frontal Lobe Lateral Rectus Inferior Turbinate Superior Rectus Inferior Rectus Maxillary Sinus Tooth
  56. 56. Grey Matter Superior Sagittal Sinus White Matter Eye Ball Maxillary Sinus Tongue
  57. 57. 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 Caudate nucleus III Pituitary stalk Pituitary gland Optic nerve Internal carotid artery Cavernous sinus
  58. 58. FLAIR & STIR SEQUENCES
  59. 59. Short TI inversion-recovery (STIR) 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.
  60. 60. Comparison of fast SE and STIR sequences for depiction of bone marrow edema FSE STIR
  61. 61. Fluid-attenuated inversion recovery (FLAIR) • First described in 1992 and has become one of the corner stones of brain MR imaging protocols • An IR sequence with a long TR and TE and an inversion time (TI) that is tailored to null the signal from CSF • Nulled tissue remains dark and all other tissues have higher signal intensities.
  62. 62. • Most pathologic processes show increased SI on T2-WI, and the conspicuity of lesions that are located close to interfaces b/w brain parenchyma and CSF may be poor in conventional T2-WI sequences. • FLAIR images are heavily T2-weighted with CSF signal suppression, highlights hyper-intense lesions and improves their conspicuity and detection, especially when located adjacent to CSF containing spaces
  63. 63. 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.
  64. 64. • Embolic infarcts- Improved visualization • Chronic infarctions- typically dark with a rim of high signal. Bright peripheral zone corresponds to gliosis, which is well seen on FLAIR and may be used to distinguish old lacunar infarcts from dilated perivascular spaces.
  65. 65. T2 W FLAIR
  66. 66. T1 W Images: Subacute Hemorrhage Fat-containing structures Anatomical Details T2 W Images: Edema Tumor Infarction Hemorrhage FLAIR Images: Edema, Tumor Periventricular lesion WHICH SCAN BEST DEFINES THE ABNORMALITY
  67. 67. • 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 DIFFUSION WEIGHTED IMAGES (DWI)
  68. 68. • Areas of restricted diffusion are BRIGHT. • Restricted diffusion occurs in – Cytotoxic edema – Ischemia (within minutes) – Abscess
  69. 69. Other Causes of Positive DWI • Bacterial abscess, Epidermoid Tumor • Acute demyelination • Acute Encephalitis • CJD • T2 shine through ( High ADC)
  70. 70. T2 SHINE THROUGH • Refers to high signal on DWI images that is not due to restricted diffusion, but rather to high T2 signal which 'shines through' to the DWI image. • T2 shine through occurs because of long T2 decay time in some normal tissue. • Most often seen with sub-acute infarctions, due to Vasogenic edema but can be seen in other pathologic abnormalities i.e epidermoid cyst.
  71. 71. • 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.
  72. 72. • Calculated by the software. • Areas of restricted diffusion are dark • Negative of DWI – i.e. Restricted diffusion is bright on DWI, dark on ADC APPARENT DIFFUSION COEFFICIENT Sequences (ADC MAP)
  73. 73. • The ADC may be useful for estimating the lesion age and distinguishing acute from subacute DWI lesions. • Acute ischemic lesions can be divided into Hyperacute lesions (low ADC and DWI-positive) and Subacute lesions (normalized ADC). • Chronic lesions can be differentiated from acute lesions by normalization of ADC and DWI.
  74. 74. Nonischemic causes for decreased ADC • Abscess • Lymphoma and other tumors • Multiple sclerosis • Seizures • Metabolic (Canavans Disease)
  75. 75. 65 year male-Acute Rt ACA Infarct DWI Sequence ADC Sequence
  76. 76. Clinical Uses of DWI & ADC in Ischemic Stroke • Hyperacute Stage:- within one hour minimal hyperintensity seen in DWI and ADC value decrease 30% or more below normal (Usually <50X10-4 mm2/sec) • Acute Stage:- Hyperintensity in DWI and ADC value low but after 5- 7days of episode ADC values increase and return to normal value (Pseudonormalization) • Subacute to Chronic Stage:- ADC value are increased but hyperintensity still seen on DWI (T2 shine effect)
  77. 77. • Post contrast images are always T1 W images • Sensitive to presence of vascular or extravascular Gd • Useful for visualization of: – Normal vessels – Vascular changes – Disruption of blood-brain barrier POST CONTRAST (GADOLINIUM ENHANCED)
  78. 78. MR ANGIOGRAPHY / VENOGRAPHY
  79. 79. • TWO TYPES OF MR ANGIOGRAPHY – CE (contrast-enhanced) MRA – Non-Contrast Enhanced MRA • TOF (time-of-flight) MRA • PC (phase contrast) MRA MR ANGIOGRAPHY
  80. 80. 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)
  81. 81. TOF (TIME OF FLIGHT) MRA  Signal from movement of unsaturated blood converted into image  No contrast agent injected  Motion artifact  Non-uniform blood signal  2D TOF- SENSITIVE TO SLOW FLOW – VENOGRAPHY  3D TOF- SENSITIVE TO HIGH FLOW – MR ANGIOGRAPHY
  82. 82. PHASE CONTRAST (PC) MRA  Phase shifts in moving spins (i.e. blood) are measured  Phase is proportional to velocity  Allows quantification of blood flow and velocity  velocity mapping possible  USEFUL FOR – CSF FLOW STUDIES (NPH) – MR VENOGRAPHY
  83. 83. Internal Carotid Artery Basilar Artery Vertebral Artery Middle Cerebral Artery Anterior Cerebral Artery Posterior Cerebral Artery Posterior Inferior Cerebellar Artery Superior Cerebellar Artery Anterior Inferior Cerebellar Artery
  84. 84. Vertebral Artery Basilar Artery Posterior Cerebral Artery Internal Carotid Artery Anterior Cerebral Artery Middle Cerebral Artery
  85. 85. MR VENOGRAPHY
  86. 86. NORMAL MR VENOGRAPHY (Lateral View) Superior Sagittal Sinus Internal Jugular Vein Sigmoid Sinus Transverse Sinus Confluence of Sinuses Straight Sinus Vein of Galen Internal Cerebral Vein
  87. 87. NORMAL MR VENOGRAPHY (Lateral View)
  88. 88. • 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)
  89. 89. • Non-invasive physiologic imaging of brain that measures relative levels of various tissue metabolites. • Used to complement MRI in characterization of various tissues. MR SPECTROSCOPY
  90. 90. Observable metabolites Metabolite Resonating Location ppm Normal function Increased Lipids 0.9 & 1.3 Cell membrane component Hypoxia, trauma, high grade neoplasia. Lactate 1.3 Denotes anaerobic glycolysis Hypoxia, stroke, necrosis, mitochondrial diseases, neoplasia, seizure Alanine 1.5 Amino acid Meningioma Acetate 1.9 Anabolic precursor Abscess , Neoplasia,
  91. 91. Metabolite Location ppm Normal function Increased Decreased NAA 2 Nonspecific neuronal marker (Reference for chemical shift) Canavan’s disease Neuronal loss, stroke, dementia, AD, hypoxia, neoplasia, abscess Glutamate , glutamine, GABA 2.1- 2.4 Neurotransmitter Hypoxia, HE Hyponatremia Succinate 2.4 Part of TCA cycle Brain abscess Creatine 3.03 Cell energy marker (Reference for metabolite ratio) Trauma, hyperosmolar state Stroke, hypoxia, neoplasia
  92. 92. Metabolite Location ppm Normal function Increased Decreased Choline 3.2 Marker of cell memb turnover Neoplasia, demyelination (MS) Hypomyelination Myoinositol 3.5 & 4 Astrocyte marker AD Demyelinating diseases
  93. 93. Metabolite ratios: Normal abnormal NAA/ Cr 2.0 <1.6 NAA/ Cho 1.6 <1.2 Cho/Cr 1.2 >1.5 Cho/NAA 0.8 >0.9 Myo/NAA 0.5 >0.8
  94. 94. MRS Dec NAA/Cr Inc acetate, succinate, amino acid, lactate Neuodegenerat ive Alzheimer Dec NAA/Cr Dec NAA/ Cho Inc Myo/NAA Slightly inc Cho/ Cr Cho/NAA Normal Myo/NAA ± lipid/lactate Inc Cho/Cr Myo/NAA Cho/NAA Dec NAA/Cr ± lipid/lactate Malignancy Demyelinating disease Pyogenic abscess
  95. 95. • ICSOLs • Differentiate Neoplasms from Nonneoplastic Brain Masses • Radiation Necrosis versus Recurrent Tumor • Inborn Errors of Metabolism • RESEARCH PURPOSE FOR NEURODEGENERATIVE DISEASES MRS APPLICATION
  96. 96.  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
  97. 97.  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
  98. 98. REFERENCES • CT and MRI of the whole body – John R Haaga (5th edition) • Osborne Brain : Imaging, Pathology and Anatomy • Neurologic Clinics (Neuroimaging) : February 2009, volume 27 • Bradley ‘s Neurology in Clinical Practice (6th edition) • Adams and Victor’s: Principles of Neurology (10th edition) • Understanding MRI : basic MR physics : Stuart Currie et al : BMJ 2012 • Harrison’s textbook of Internal Medicine (18th edition)
  99. 99. THANK YOU
  100. 100. • CISS / 3D FIESTA SEQUENCE • Heavily T2 Wtd Sequences • Allows much higher resolution and clearer imaging of tiny intracranial structures CRANIAL NERVES IMAGING
  101. 101. MAGNETIZATION TRANSFER (MT) MRI • MT is a recently developed MR technique that alters contrast of tissue on the basis of macromolecular environments. • MTC is most useful in two basic area, improving image contrast and tissue characterization. • MT is accepted as an additional way to generate unique contrast in MRI that can be used to our advantage in a variety of clinical applications.
  102. 102. 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

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