This document provides an overview of MRI brain imaging. It begins with the anatomy of the brain and basic MRI principles. It then covers indications for brain MRI, patient preparation including positioning in the scanner, and common sequences used. T1-weighted, T2-weighted, FLAIR and diffusion-weighted sequences are described in terms of their characteristics. Contrast agents, safety procedures, and specialized protocols for conditions like epilepsy are also summarized. The document aims to inform about all aspects of performing and interpreting a brain MRI exam.

1. MRI
BRAIN
Presentation by :-
GYANDEEP
MTR-269
AIIMS DELHI

2. OUTLINE
• Anatomy
• Basics
• Indications
• Contraindications
• Patient Preparation
• Positioning
• Planning/Sequences
• Image Characterization
• MRI Safety

3. ANATOMY
Brain
Forebrain
Midbrain
Hindbrain
Cerebrum
Thalamus
Hypothalamus
Hippocampus
Cerebellum
Pons
Medulla
Oblongata

6. ANATOMY

7. Genu of corpus
callosum
Splenium of
corpus callosum
Cerebellum
Lateral
ventricle
Midbrain
Pons
Medulla
oblongata
Fourth
ventricle
Spinal cord
Thalamus
Hypothalamus
Cerebrum

8. Gray matter and white matter
• Gray and white matter are two different regions of the
central nervous system. In the brain, gray matter refers to
the darker, outer portion, while white matter describes the
lighter, inner section underneath.

9. BODY PLANES
AXIAL/TRANSVERSE
SAGITTAL CORONAL
1. Axial Plane - Divides the body into superior and
inferior parts.
2. Sagittal Plane - Divides the body into right half and
left halves.
3. Coronal Plane - Divides the body into anterior and
posterior parts.

10. AXIAL SAGITTAL CORONAL

11. MRI V/S CT
 CT is a map of tissue density - white areas
represent higher density tissues than blacker
areas.
 MRI is a map of proton energy in tissues of
the body – white areas represent high ‘signal’.
CSF is low density on CT.
 CSF is white on this MRI image – indicating
high signal.

12. Advantages of MRI over CT
in Brain Imaging
• MRI does not use ionizing radiation, and is thus preferred over CT in children and
patients requiring multiple imaging examinations.
• MRI has a much greater range of available soft tissue contrast and anatomy in
greater detail.
• MRI scanning can be performed in any imaging plane without having to
physically move the patient.
• MRI contrast agents have a considerably smaller risk of causing potentially lethal
allergic reactions.

13. INDICATIONS
 Stroke
 Epilepsy , Seizures
 Infection
 Inflammation
 Abscess
 Tumour
 Multiple Sclerosis
 Chronic severe Headache
 Dementia
Congenital malformations
 Pituitary fossa pathology

14. CONTRAINDICATIONS
• Any electrically, magnetically or mechanically activated implant :-
- Cardiac pacemaker
- Insulin pump biostimulator
- Cochlear implant
- Hearing aids
• Intracranial aneurysm clips.
• Metallic foreign body in the eye.
• Metal shrapnel or bullet.
• Claustrophobic

15. Patient Preparation
1. Instructions for fasting :
- Fasting not required ( for non contrast study )
- Instruct the patient to report empty stomach
( patients needing contrast study )
2. Contrast media should only be given to patient if blood urea
and serum creatinine levels are within the normal range.
i.e.- Blood urea - 17 – 49
Creatinine - 0.5 - 0.9
3. Ask the patient to provide complete details regarding the
implant used ( if any ) since it may be contraindicated for MRI.
4. A satisfactory written informed consent form must be taken
from patient.

16. 5. Ask the patient to remove all metallic objects including keys,
coins, wallet, cards with magnetic strips, jewellery, hearing aid and
hairpins.
6. Explain the procedure to patient.
7. Instruct the patient to keep still.
8. Disposable ear plugs should be provided to patient to devoid
the patients from repeated noises during scanning.

17. Positioning
16 Channels Brain
Coil

18. Positioning
• Head first supine.
• Position the head in the Brain coil/head coil and
immobilise with pads/cushions.
• Give pads/cushions under the legs for extra
comfort.
• Centre the laser beam localiser over the glabella.

19. BRAIN AIIMS
Survey
T2W_TSE (TRA)
FLAIR (TRA)
T1W_TSE (TRA)
DWI (TRA)
SWI (TRA)
T2W_TSE (SAG)
T2W_TSE (COR)
T1W_SE_PG (TRA)
T1W_SE_PG (SAG)
T1W_SE_PG (COR)
Sequences

20. Planning
1. Survey :-
A three plane survey must be taken in the beginning to localize and
plan the sequences. Survey images are T1 weighted low resolution
scans.

21. 4. T2W_TSE (SAG)
• Plan the sagittal slices on the axial plane; angle the position block parallel
to midline of the brain. Check the positioning block in the other two planes.
An appropriate angle must be given in the coronal plane on a tilted head
(parallel to the line along 3rd ventricle and brain stem). Slices must be
sufficient to cover the brain from temporal lobe to temporal lobe.
•SLICE THICKNESS – 5MM

22. 2. T2W_TSE (TRA)
• Plan the axial slices on the sagittal plane; angle the position block
parallel to the genu and splenium of the corpus callosum. Slices must
be sufficient to cover the whole brain from the vertex to the line of the
foramen magnum. Check the positioning block in the other two planes.
An appropriate angle must be given in coronal plane on a tilted head
(perpendicular to the line of 3rd ventricle and brain stem).
•SLICE THICKNESS – 5MM

23. 3. FLAIR (TRA)
• Plan the axial slices on the sagittal plane; angle the position block
parallel to the genu and splenium of the corpus callosum. Slices
must be sufficient to cover the whole brain from the vertex to the
line of the foramen magnum. Check the positioning block in the
other two planes. An appropriate angle must be given in coronal
plane on a tilted head (perpendicular to the line of 3rd ventricle and
brain stem).

24. 5. T2W_TSE (COR)
• Plan the coronal slices on the sagittal plane; angle the position
block perpendicular to the corpus callosum. Check the positioning
block in the other two planes. An appropriate angle must be given in
the axial plane on a tilted head (perpendicular to mid line of the
brain). Slices must be sufficient to cover the whole brain from the
frontal sinus to the line of the occipital protuberance.

25. Epilepsy Protocol
Indications :
 Onset of partial seizures, at any age.
 Onset of generalised or unclassified seizures in the first year of life, or in
adulthood.
 Difficulty obtaining seizure control with first-line antiepileptic drugs (AEDs).
 Loss of seizure control, or a change in the pattern of seizures.
Region of Interest :- Hippocampus.
Sequences :
 T2_TSE_CORONAL_OBLIQUE
 T1_TSE_CORONAL_OBLIQUE

26. T2W_TSE_CORONAL_OBLIQUE
• Plan the coronal high resolution slices on the sagittal plane; angle
the position block plane perpendicular to the long axis of the
hippocampus. Check the positioning block in the other two planes.
An appropriate angle must be given in the axial plane (perpendicular
to mid line of the brain). Slices must be sufficient to cover the whole
temporal lobe.

27. CONTRAST MEDIA
• Gadolinium(Gd) based contrast agents are used.
• Dose – 0.2 ml/kg.(max. dose).

28.  When contrast is present in your body, it alters the magnetic
properties of nearby water molecules, which enhances the quality of
the images. This improves the sensitivity and specificity of the
diagnostic images.
Contrast material enhances the visibility of the following:
 Tumors.
 Inflammation.
 Certain organs’ blood supply.
 Blood vessels.
 The contrast can also help diagnose multiple sclerosis, stroke,
dementia and infection.

29. Characterise Image
• When a patient is placed in the magnet the hydrogen atoms in the water of
their body tissues line up along the magnetic field. Radiofrequency pulses
are sent in, causing the atoms to ‘flip’ into another plane and then ‘relax’
back when the pulse is turned off. This recovery process is known as
relaxation.
• .This relaxation time varies from one type of tissue to another. This
difference in relaxation times is used in MRI to distinguish normal and
pathologic tissues.
• Each tissue is characterized by two relaxations times: T1 (longitudinal
relaxation time) and T2 (transverse relaxation time). Most of the images are
created by one of these two characteristics being the predominant source of
contrast. This means when an image is described as a T1-weighted image T1
is the main source of contrast.

30. T1W IMAGE :
• The easiest way to identify T1 weighted images is to look for fluid filled
spaces in the body (e.g. Cerebrospinal fluid in the brain ventricles and spinal
canal, free fluid in the abdomen, fluid in the gall bladder and common bile
duct, synovial fluid in joints, fluid in the urinary tract and urinary bladder,
edema or any other pathological fluid collection in the body).
Fluids normally appear dark on a T1W Image.
 Useful for Anatomy.
• Gray matter : - gray.
• White matter : - whiter.
• Fluids : - dark.
• Fat : - bright.

31. T2W IMAGE :
• The easiest way to identify T2 weighted images is to look for fluid filled
spaces in the body (e.g. Cerebrospinal fluid in the brain ventricles and spinal
canal, free fluid in the abdomen, fluid in the gall bladder and common bile
duct, synovial fluid in joints, fluid in the urinary tract and urinary bladder,
edema or any other pathological fluid collection in the body).
• Fluids normally appear bright on T2 weighted images.
 Useful for Pathology.
• Gray matter : - whiter.
• White matter : - darker than gray.
• Fluids : – bright.
• Fat : - Darker than the fat signal
on T1 images.

32. FLAIR IMAGE :
• FLAIR is another variation of the inversion recovery sequence. In FLAIR, the
signal from fluid is nullified by using a long effective echo time and long
inversion time. This sequence is commonly used in the brain and spinal cord
where the lesions are normally covered by bright cerebrospinal fluid (CSF)
signals. A long inversion time suppresses the high CSF signal and improve the
visualization of small periventricular and spinal cord lesions.
• Fluids normally appear dark and lesions or other pathological processes
appear bright on image. Images normally appear as a fluid suppressed T2
image.
• Gray matter : - whiter.
• White matter : - darker than gray.
• Fluids : – dark.
• Pathologies :- Bright/white.

35. Diffusion-weighted Imaging(DWI)
• Diffusion-weighted magnetic resonance imaging (DW MRI) provides image
contrast that is dependent on the random microscopic motion of water protons,
which may be substantially altered by different pathological process.

36. MRI SAFETY
Do not bring ferro-magnetic objects into the examination
room. The attraction by the magnet may lead to serious or
fatal injury to patient
1. Projectile Effects :-
2. Implants :- Adhere strictly to the conditions as specified by the implant
manufacturer. If conditions are not known , do not scan.
3. Nurse Call/ Hearing Protection :- Use the nurse call with every patient and give
instructions about its use. Provide appropriate
hearing protection for every patient and anyone else
in the room.
4. Patient Positioning :- Prevent contact between body parts or skin
and coil cables. Verify clearance between
body parts and the bore wall.

37. Acknowledgments
• Head and Professor – Dr. Deep N. Shrivastava.
• Dr. Madhusudhan.
• Dr. Chandan J. Das.
• Mr. Pawan Kumar Popli.
• Mr. Lalit Gupta.