MRI, PET, SPECT, and fMRI are brain imaging techniques. MRI uses magnetism and radio waves to produce detailed soft tissue images. It is based on proton excitation and relaxation. PET involves injecting radioactive tracers to show brain activity and function. SPECT uses gamma rays to create 3D images of blood flow. fMRI detects oxygen level changes to map neural activity areas. Each technique has advantages like no radiation (MRI) or ability to repeat scans (fMRI), and disadvantages such as expense, long scan times, or sensitivity to movement.

1. BRAIN
IMAGING TECHNIQUES
(MRI, PET, SPECT, fMRI)
Mr. SACHIN
M.Sc. NEUROSCIENCE
GURUGRAM UNIVERSITY

2. MRI ( Magnetic Resonance Imaging)
• MRI is a radiology technique
• That uses magnetism, radio waves, and a computer to
produce images of body structures.
• MRI is based on the principles of NMR
• In 1997 the first MRI exam was performed on a
human being.
• It took 5 hours to produce one image.

3. PRINCIPLE
•MRI makes use of the magnetic properties of
certain atomic nuclei.
• Hydrogen nucleus (single proton) present in
water molecules, and therefore in all body
tissues.
•The hydrogen nuclei partially aligned by a strong
magnetic field in the scanner.

4. CONTI..
•The nuclei can be rotated using radio waves, and
they subsequently oscillate in the magnetic field
while returning to equilibrium.
• Simultaneously they emit a radio signal.
•This is detected using antennas (coils)
•Very detailed images can be made of soft
tissues.

7. MRI scanning is based on the excitation and relaxation of
protons.

8. WHO CAN'T HAVE AN MRI SCAN?
•A cardiac pacemaker
•Certain clips in your head from brain operations
•A cochlear implant
•A metallic foreign body in your eye
•Had surgery in the last 8 weeks
•If you are pregnant

9. Indication Of MRI
• Stroke
• Temporal lobe epilepsy,
• Infection,
• Inflammation,
• Tumour,
• Multiple sclerosis (MS),
• Etc.

10. Advantage
• No overlapping artifact
• Excellent resolution
• Very good at detecting fluid
• Excellent for imaging the
brain, spine and joints
• No radiation
• Multiple imaging tests
within the same study (T1,
T2, IR, GE)
Disadvantage
•Very expensive
•Patients cannot have a
pacemaker or ferromagnetic
material
• Slower to acquire images
(approximately 45 minutes)

11. Positron Emission Tomography (PET) scans
3-dimensional images of the inside of the body.
The images can clearly show the part of the body being investigated, including
any abnormal areas, and can highlight how well certain functions of the body are
working.
PET scans are often combined with CT scans to produce even more detailed
images. This is known as a PET-CT scan.
They may also occasionally be combined with an MRI scan (known as a PET-
MRI scan).

12. fluorodeoxyglucose

15. PET scan

16. Indication of PET scan
• Cancer.
• Epilepsy.
• Infection (More than-15 days).
• Test to treatment Development.
• Brain functioning.
• Dementia.
• Single part supporting.
• PET may be use for Chemotherapy

17. How to prepare for PET scan

18. Risk and side effects of PET scan
• A PET scan is painless and has few risks and side
effects. But you may have discomfort or problems,
such as:
• Pain or redness where a tracer is injected
• Claustrophobia
• Allergic reactions to a tracer, although this rarely
happens and may be a mild reaction

19. SPECT Scan
• Single Photon Emission Computed Tomography
• The first SPECT measurements were performed in the
1960s (Kuhl and Edwards, 1964).
• Shows how blood flows through arteries and veins in
the brain
• Can detect reduced blood flow in the brain.

20. SPECT scan Images

21. Single Photon Emission computed
Tomography (SPECT)
• SPECT generates transverse image with the
distribution of X- ray or GAMMA – ray emitting nuclei
in the patient.
• Most widely used radioactive tracers for SPECT are
Hexamethyl propylene amine oxime
 gamma cameras are used for SPECT acquisition.
 3D image

22. Indication of SPECT scan
• BRAIN DISORDER- SPECT Can be helpful in
determining which parts of brain are being affected.
• Dementia
• Clogged Blood Vessels
• Seizures
• Epilepsy
• Head Injuries.

23. Patient prepare for SPECT
• The patient prepare for a SPECT Scan depend on the patient particular
Situation.
• In general, The patient Should:
• Leave metallic jewelry at home.
• Inform the technologist if the patient Pregnant
• Bring a list of all the medication and supplements the patient take.

24. Risk of SPECT scan
• For most people , SPECT Scan are safe
• If the patient receive an injection of radioactive tracer , the patient
may experience .
• Bleeding , pain or swelling where the needle was inserted in the
patient ARM.
• Rarely an Allergic reaction to the radioactive tracer.

25. FUNCTIONAL MAGNETIC RESONANCE
IMAGING SCAN (fMRI)
• Neurons consume oxygen and nutrients
• Increased neural activity requires increased supply of oxygen
• oxygen is bound to hemoglobin (oxyhemoglobin vs. de-
oxyhemoglobin) to supply neurons with oxygen and glucose, blood
flow is increased locally
• The local increase in blood flow leads to a displacement of de-
oxyhemoglobin
• MR signal is higher for oxygenated compared to de-oxygenated
blood

26. fMRI..

27. fMRI
• The image shows areas active for visual memory (green), aural
memory (red), and both types of memory (yellow).

29. fMRI
Advantages
• It requires no contrast agent.
• High quality anatomical
images can be obtained in
the same session as the
functional studies.
• . Can be repeated multiple
times
Disadvantages
• Cannot perform receptor-
ligand studies like PET and
• SPECT Extremely sensitive to
head movements.
• Loud sound from magnets

30. Reference
• Wikipedia
• Neuroscience book
• Google

31. THANKYOU