normal mri brain
TRANSCRIPT
![Page 1: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/1.jpg)
NORMAL MRI BRAIN
DR. PIYUSH OJHADM RESIDENT
DEPARTMENT OF NEUROLOGYGOVT MEDICAL COLLEGE, KOTA
![Page 2: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/2.jpg)
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
![Page 3: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/3.jpg)
The first Human MRI scan was performed on 3rd july 1977 by Raymond Damadian, Minkoff and Goldsmith.
![Page 4: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/4.jpg)
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
![Page 5: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/5.jpg)
• MRI is based on the principle of nuclear magnetic resonance (NMR)
• Two basic principles of NMR1. 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
![Page 6: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/6.jpg)
• 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
![Page 7: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/7.jpg)
• 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
![Page 8: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/8.jpg)
BASIC MR BRAIN SEQUENCES
• T1• T2• FLAIR• DWI• ADP• MRA• MRV• MRS
![Page 9: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/9.jpg)
• SHORT TE• SHORT TR
• BETTER ANATOMICAL DETAILS• FLUID DARK• GRAY MATTER GRAY• WHITE MATTER WHITE
T1 W IMAGES
![Page 10: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/10.jpg)
• 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
![Page 11: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/11.jpg)
T1 W IMAGES
![Page 12: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/12.jpg)
• LONG TE• LONG TR
• BETTER PATHOLOGICAL DETAILS• FLUID BRIGHT • GRAY MATTER RELATIVELY BRIGHT• WHITE MATTER DARK
T2 W IMAGES
![Page 13: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/13.jpg)
T1W AND T2 W IMAGES
![Page 14: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/14.jpg)
• 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
![Page 15: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/15.jpg)
CT
FLAIRT2
T1
![Page 16: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/16.jpg)
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
![Page 17: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/17.jpg)
MRI BRAIN :AXIAL SECTIONS
![Page 18: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/18.jpg)
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
![Page 19: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/19.jpg)
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
![Page 20: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/20.jpg)
ICA
Temporallobe
Post Contrast sagittal T1 Wtd M.R.I.
Section at the level of Pons
Cerebellar Hemisphere
Vermis
IV Ventricle
Pons
Basilar Artery
Cavernous Sinus
MCPIAC
Mastoid Sinus
![Page 21: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/21.jpg)
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 Artery Middle Cerebral Artery
Midbrain
FrontalLobe
Temporal Lobe
Occipital Lobe
![Page 22: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/22.jpg)
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
![Page 23: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/23.jpg)
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
![Page 24: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/24.jpg)
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
![Page 25: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/25.jpg)
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
![Page 26: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/26.jpg)
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
![Page 27: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/27.jpg)
MRI BRAIN :SAGITTAL SECTIONS
![Page 28: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/28.jpg)
Grey Matter
White Matter
![Page 29: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/29.jpg)
White Matter
Cerebellum
Grey Matter
Frontal Lobe
Parietal Lobe
Temporal Lobe
Lateral Sulcus Occipital Lobe
![Page 30: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/30.jpg)
Gyri of cerebral cortex
Sulci of cerebral Cortex
Cerebellum
Frontal LobeTemporalLobe
![Page 31: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/31.jpg)
Frontal Lobe
Temporal Lobe
Parietal Lobe
OccipitalLobe
Cerebellum
![Page 32: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/32.jpg)
Frontal Lobe
Parietal Lobe
Orbit
Occipital Lobe
Transverse sinus
Cerebellar Hemisphere
![Page 33: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/33.jpg)
Optic Nerve
Precentral Sulcus
Lateral Ventricle
Occipital Lobe
Maxillary sinus
![Page 34: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/34.jpg)
Caudate Nucleus
Corpus callosum
Thalamus
Tongue
Pons
Tentorium Cerebell
![Page 35: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/35.jpg)
Splenium of Corpus callosum
Pons
Ethmoid air Cells
Inferior nasalConcha
Midbrain
Fourth Ventricle
Genu of CorpusCallosum
Hypophysis
Thalamus
![Page 36: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/36.jpg)
Splenium of Corpus callosumGenu of corpus
callosum
Pons
SuperiorColliculus
Inferior Colliculus
NasalNasal Septuml
Medulla
Body of corpus callosum
Thalamus
![Page 37: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/37.jpg)
Cingulate Gyrus
Genu of corpuscallosum
Ethmoid air cells
Oral cavity
Splenium of Corpus callosum
Fourth Ventricle
![Page 38: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/38.jpg)
FrontalLobe
MaxillarySinus
Parietal Lobe
Occipital Lobe
Corpus CallosumThalamus
Cerebellum
![Page 39: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/39.jpg)
Frontal Lobe
TemporalLobe
Parietal Lobe
Lateral Ventricle
Occipital Lobe
Cerebellum
![Page 40: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/40.jpg)
Frontal Lobe
Parietal Lobe
Superior Temporal Gyrus
Lateral Sulcus
Inferior Temporal Gyrus
Middle Temporal Gyrus
External Auditory Meatus
![Page 41: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/41.jpg)
. 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
![Page 42: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/42.jpg)
MRI BRAIN :CORONAL SECTIONS
![Page 43: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/43.jpg)
LongitudinalFissure
Straight Sinus
Superior Sagittal Sinus
Sigmoid Sinus
Vermis
![Page 44: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/44.jpg)
Straight Sinus
Cerebellum
Lateral Ventricle,Occipital Horn
![Page 45: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/45.jpg)
Arachnoid Villi
Great CerebralVein
TentoriumCerebelli
Falx Cerebri
Lateral Ventricle
Vermis ofCerebellum
Cerebellum
![Page 46: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/46.jpg)
Splenium ofCorpus callosum
Posterior CerebralArterySuperior CerebellarArtery
Foramen Magnum
Lateral Ventricle
Internal CerebralVein
Tentorium Cerebelli
Fourth Ventricle
![Page 47: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/47.jpg)
Cingulate Gyrus
Choroid Plexus
Superior Colliculus
Cerebral Aqueduct
Corpus Callosum
Thalamus
Pineal Gland
Vertebral Artery
![Page 48: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/48.jpg)
Insula
Lateral Sulcus
Cerebral Peduncle
Olive
Crus of Fornix
Middle CerebellarPeduncle
![Page 49: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/49.jpg)
Caudate Nucleus
Third Ventricle
Hippocampus
Pons
Corpus Callosum
Thalamus
CerebralPeduncle
Parahippocampalgyrus
![Page 50: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/50.jpg)
Lateral VentricleBody of Fornix
Temporal Horn of Lateral Ventricle
Uncus of Temporal Lobe
Third Ventricle
Hippocampus
![Page 51: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/51.jpg)
Internal CapsuleCaudate Nucleus
Optic Tract
InsulaLentiform Nucleus
Parotid Gland
Amygdala
Hypothalamus
![Page 52: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/52.jpg)
Internal Capsule
Cingulate Gyrus
Optic Nerve
Nasopharynx
Internal Carottid Artery
Lentiform Nucleus
Caudate Nucleusa
![Page 53: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/53.jpg)
LongitudinalFissure
Superior SagittalSinus
Lateral Sulcus
Parotid Gland
Genu Of Corpus Callosum
Temporal Lobe
![Page 54: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/54.jpg)
Ethmoid Sinus
Frontal Lobe
Nasal Turbinate
Massetor
Nasal Septum
Nasal Cavity
Tongue
![Page 55: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/55.jpg)
Medial Rectus
Frontal Lobe
Lateral Rectus
Inferior Turbinate
Superior Rectus
Inferior Rectus
Maxillary Sinus
Tooth
![Page 56: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/56.jpg)
Grey Matter
Superior Sagittal Sinus
White Matter
Eye Ball
Maxillary Sinus
Tongue
![Page 57: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/57.jpg)
Coronal Section of the Brain at the level of Pituitary glandPost Contrast Coronal T1 Weighted MRI
sp
np
Frontal lobe
Corpus callosum
Frontal horn
Caudate nucleus
III
Pituitary stalk
Pituitary glandOptic nerve
Internal carotid artery
Cavernous sinus
![Page 58: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/58.jpg)
FLAIR & STIR SEQUENCES
![Page 59: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/59.jpg)
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.
![Page 60: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/60.jpg)
Comparison of fast SE and STIR sequences for depiction of bone marrow edema
FSE STIR
![Page 61: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/61.jpg)
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.
![Page 62: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/62.jpg)
• 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
![Page 63: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/63.jpg)
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.
![Page 64: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/64.jpg)
• 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.
![Page 65: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/65.jpg)
T2 WFLAIR
![Page 66: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/66.jpg)
T1 W Images:Subacute HemorrhageFat-containing structuresAnatomical Details
T2 W Images:EdemaTumorInfarctionHemorrhage
FLAIR Images:Edema, TumorPeriventricular lesion
WHICH SCAN BEST DEFINES THE ABNORMALITY
![Page 67: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/67.jpg)
• 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)
![Page 68: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/68.jpg)
• Areas of restricted diffusion are BRIGHT.
• Restricted diffusion occurs in – Cytotoxic edema– Ischemia (within minutes) – Abscess
![Page 69: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/69.jpg)
Other Causes of Positive DWI
• Bacterial abscess, Epidermoid Tumor• Acute demyelination• Acute Encephalitis• CJD• T2 shine through ( High ADC)
![Page 70: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/70.jpg)
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.
![Page 71: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/71.jpg)
• 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.
![Page 72: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/72.jpg)
• 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)
![Page 73: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/73.jpg)
• 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.
![Page 74: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/74.jpg)
Nonischemic causes for decreased ADC• Abscess
• Lymphoma and other tumors
• Multiple sclerosis
• Seizures
• Metabolic (Canavans Disease)
![Page 75: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/75.jpg)
65 year male-Acute Rt ACA Infarct
DWI Sequence ADC Sequence
![Page 76: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/76.jpg)
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)
![Page 77: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/77.jpg)
• 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)
![Page 78: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/78.jpg)
![Page 79: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/79.jpg)
MR ANGIOGRAPHY / VENOGRAPHY
![Page 80: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/80.jpg)
• TWO TYPES OF MR ANGIOGRAPHY
– CE (contrast-enhanced) MRA
– Non-Contrast Enhanced MRA• TOF (time-of-flight) MRA• PC (phase contrast) MRA
MR ANGIOGRAPHY
![Page 81: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/81.jpg)
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)
![Page 82: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/82.jpg)
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
![Page 83: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/83.jpg)
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
![Page 84: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/84.jpg)
![Page 85: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/85.jpg)
MR ANGIOGRAPHY
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
![Page 86: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/86.jpg)
MR ANGIOGRAPHY
Vertebral Artery
Basilar Artery
Posterior Cerebral Artery
Internal Carotid Artery
Anterior Cerebral Artery
Middle Cerebral Artery
![Page 87: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/87.jpg)
MR VENOGRAPHY
![Page 88: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/88.jpg)
![Page 89: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/89.jpg)
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
![Page 90: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/90.jpg)
NORMAL MR VENOGRAPHY (Lateral View)
![Page 91: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/91.jpg)
• 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 / calcificationLook for: DARK only
GRE Sequences (GRADIENT RECALLED ECHO)
![Page 92: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/92.jpg)
GREFLAIR
Hemorrhage in right parietal lobe
![Page 93: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/93.jpg)
• 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
![Page 94: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/94.jpg)
NORMAL MR SPECTRUM
![Page 95: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/95.jpg)
Observable metabolitesMetabolite Resonating
Locationppm
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,
![Page 96: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/96.jpg)
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
![Page 97: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/97.jpg)
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
ADDemyelinating
diseases
![Page 98: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/98.jpg)
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
![Page 99: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/99.jpg)
MRS
Dec NAA/CrInc acetate,
succinate, amino acid, lactate
Neuodegenerative
Alzheimer
Dec NAA/CrDec NAA/
ChoInc
Myo/NAA
Slightly inc Cho/ CrCho/NAA
Normal Myo/NAA± lipid/lactate
Inc Cho/CrMyo/NAACho/NAA
Dec NAA/Cr± lipid/lactate
Malignancy Demyelinating disease Pyogenic
abscess
![Page 100: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/100.jpg)
• ICSOLs• Differentiate Neoplasms from Nonneoplastic
Brain Masses• Radiation Necrosis versus Recurrent Tumor• Inborn Errors of Metabolism• RESEARCH PURPOSE FOR
NEURODEGENERATIVE DISEASES
MRS APPLICATION
![Page 101: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/101.jpg)
Perfusion is the process of nutritive delivery of arterial
blood to a capillary bed in the biological tissue
Lower perfusion means that the tissue is not getting
enough blood with oxygen and nutritive elements
(ischemia)
Higher perfusion means neoangiogenesis – increased
capillary formation (e.g. tumor activity)
PERFUSION STUDIES
![Page 102: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/102.jpg)
Stroke Detection and
assessment of ischemic stroke
(Lower perfusion )
Tumors Diagnosis, staging, assessment of tumour grade and prognosisTreatment responsePost treatment evaluationPrognosis of therapy effectiveness (Higher perfusion)
APPLICATIONS OF PERFUSION IMAGING
![Page 103: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/103.jpg)
![Page 104: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/104.jpg)
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)
![Page 105: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/105.jpg)
THANK YOU
![Page 106: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/106.jpg)
• CISS / 3D FIESTA SEQUENCE
• Heavily T2 Wtd Sequences
• Allows much higher resolution and clearer imaging of tiny intracranial structures
CRANIAL NERVES IMAGING
![Page 107: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/107.jpg)
I AND II N III N
V N VI N
![Page 108: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/108.jpg)
VII AND VIII N
LOWER CRANIAL N
![Page 109: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/109.jpg)
TRIGEMINAL NEURALGIA
![Page 110: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/110.jpg)
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.
![Page 111: Normal mri brain](https://reader036.vdocuments.us/reader036/viewer/2022081414/58f9b222760da3da068bc823/html5/thumbnails/111.jpg)
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