PET & MRI scan- Indication, Preparation, Position Of The Patient!

PET scan rotating brain (gif)
PET scan rotating brain

By the end of this article, you would be able to:

What is PET scan (Positron Emission Tomography) & MRI Scan (Magnetic Resonance Imaging) Moreover, IndicationsPreparationDefinition, etc? 

PET scanning machine picture
PET scanning machine

What is a PET scan? 

A PET scan is a diagnostic imaging technique in which parents are given a special radioactive substance that emits positrons; these, in turn, grow rise to gamma rays, which are detected by a gamma camera. It gives a three-dimensional image or picture of functional processes in the body. 

Many different radioisotopes are useful in PET scanning. Such as Fluorine-18, Oxygen-15, and Carbon-11. 3F has commonly used isotopes. It replaces the hydroxyl (OH) group of molecules of interest. A PET scan demonstrates the biological functions of the body before anatomical changes take place, while the CT scan provides information about the body's anatomy such as size, shape, and location. 

PET scans of brain tumor using sigma-2 ligands


  1. To detect malignancy 
  2. To diagnose Seizures/Epilepsy, Alzheimer's and other Dementias, Schizophrenia, Depression, Attention Deficit Disorder (ADD), and other neurologic disorder. 


  • PET Camera
  • Medical Cyclotron( for the production of Radioisotopes) 

Preparation of the patient

  • Explain the procedure to the patient 
  • The patient is asked to wear a gown during the exam
  • Make sure that the patient is not pregnant
  • 6 hours of fasting is required
  • Explain to the patient that radio Isotopes has to be given intravenously half prior to the study. 
  • The patient is asked to lie down quietly for about 30 minutes after the injection. It is very important to stay as still as possible during this time.

PET scan

Post-Procedure care 

  • Inform the patient once the procedure is completed
  • Help him; her to be oriented back to set up
  • Make arrangements to send the patient back to the ward OPD. (specific points will be discussed under each system)

What is an MRI scan?

MRI scanning machine
MRI scanning machine

The full form of MRI (magnetic, Resonance Imaging), his technique of tomography-based upon the magnetic behavior of protonsespecially H+ in the body tissues when subjected to the magnetic field and RF pulses.

Head MRI image
Head MRI image

Indications of MRI scan

  1. Tumor of brain or meninges
  2. Skull base or orbital tumor
  3. Pituitary tumor
  4. Inflammation of the  brain meninges 
  5. Encephalopathy
  6. Encephalitis
  7. ENT problems- following consultation with a Radiologist
  8. The demyelinating disease of the brain
  9. Congenital problems
  10. Head trauma 
  11. Epilepsy
  12. Stroke
  13. Post-operative follow-up after brain surgery
  14. Spinal cord compression (acute)
  15. Radiculopathy with neurological signs
  16. Trauma 
  17. Tumour and infection arising in bone or other connective tissue
  18. Infections arising in bone or other connective tissue
MRI head scanning picture


Ferromagnetic implants (e.g.: Cardiac pacemakers, metallic orthopedic device, metal aneurysm dips, cardiac valve. for cardiac pacemaker and prosthetic valve, patients asked to get the card of the manufacturer along with him/her).


  1. MRI machine
  2. RF coil

Preparation of the patient

  • Explain the sequence of procedure 
  • Inform the patient that MRI is a painless procedure that does not require ionizing radiation and has no known risks
  • Explain to the patient that he/she will lie flat on a narrow table inside the round opening of a large magnet and patient that he/she should lie motionless during the scan
  • Tell him/her that they will hear a soft humming sound and on-off pulses of radiofrequency waves

Related Topics #sonography

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