Brain Perfusion

Indications:
Evaluate:
Cerebrovascular Accidents
Head Trauma
Possible Brain Death
Localization of Cerebral Ischemia
Localization of Brain Perfusion
Convulsive Disorders
Neuropsychiatric Disorders

Assessment of:
Tissue Viability
Cognitive Functions
Stroke
Dementia
CVD
Brain Death
Epilepsy
Movement disorders
Head Trauma

Further Evaluation of the brain due to abnormal results from other studies



Contraindications:
If the patient is uncooperative and cannot keep their head still which will in effect cause artifacts in the final image and you could miss defects.

If the patient did not adhere to the proper patient preparations and took medications that were suppose to be discontinued prior to the scan.

Questions asked in Patient History:
Can the sit still for 1 hour?
Have they been diagnosed with any preexisting neurological problems? ( you may need to closely watch patients with epilepsy for example.)
Are the pregnant or breast feeding?
DO YOU HAVE ANY QUESTIONS?

Radiopharmaceutical information:
  • Radionuclide: Tc-99m
  • Radiopharmaceutical: Tc-99m ECD(Ethyl Cysteinate Dimer) or Tc-99m HMPAO( Hexamethyl-Propylene-amine oxime)
  • Adult dosing: 20mCi
  • Pediatric dosing: (age +1)/(age +7)*Adult Dose
  • Method of administration: IV
  • Method of Localization: ECD - Passively diffused to brain and once metabolized in the brain cells, it becomes a less polar and less diffusible compound.
  • HMPAO - Passive Diffusion, same as ECD.
  • Physical Half-life: 6 Hours


Patient Preparation:
Verify the order and the Patient ID
Explain the procedure and ask if they have any questions
No Caffeine, Nicotine or Alcohol for 24 hours prior to injection
Make sure the patient lays down and stays still for at least 1 hour
Avoid any stimulation to the brain as noise can affect the temporal region and show increased uptake, visual stimulates can cause increased uptake to occiptal region of the brain and possibly skew the image (reason the patient must sit in a quiet, dimly lit room.



Side Effects:

The Patient Should not have any side effects

Equipment Used:
Gamma Camera, Preferable Dual Head
Collimator used: LEHR or LE ultra HR
Velcro Strap to minimize any possible patient movement.

Acquisition Setup:

Photopeak(s): 140KeV for Tc-99m

Window(s): 20%


Dynamic: View(s)
Matrix:64x64 zoom 2
Time/Frame: 1sec/frame
Number of Frames: 30-60
This is to make sure the injection is in the vein
SPECT:
Circular Rotation
Total Rotation: 360
Starting point: 0
Matrix: 64x64 Zoom 2
Time/Azmuiths: 40 seconds
Number of Azmuiths:40-64
Step and Shoot

Processing:


Filter: Hamming
Cut-off: 1.2
Frequency: High Frequency


Procedure:
Verify patient using name and DOB
Verify Doctors order for test
Explain Procedure and ask if the patient has any questions
Start IV then move patient to a dimly lit quiet room where they can lay down
Make sure they are relaxed before the injection in a dark and quiet room
Inject 20mCi of Tc-99m HMPAO or ECD with their eyes opened
Wait 15min to 2-3 Hours before imaging (optimal time is 1 hour)
Head must be totally in FOV
Move Collimators as close as possible and record radius(within 11-15cm)


Normal Uptake and common varients:
Insert an image of a normal scan. Describe the normal uptake, and any normal varients visualized.
brain_spect_1_small.jpg
You can observe the normal perfusion throughout the whole corticies of the brain as there is no signs of hypoperfusion
Abnormal Uptake and causes:
Insert an image of an abnormal scan. Describe the abnormal uptake, and the cause of the abnormal uptake.
external image 63d0f2b163375161c4cdc79aa47509.jpg
You can notice the decreased bilateral perfusion is the parietal and temporal lobes consistent with Alzheimer's disease on this SPECT image.
Artifacts:
Insert an image with an artifact, and explain what the artifact is.

Common artifacts in brain perfusion imaging would be patient movement and possibly incorrect attenuation corrections on the reconstruction program on the computer. Velcro straps can be used to minimize the patient movements as the patient are under the camera for 30 minutes to an hour.


References:
Nuclear Medicine: The Requisites by Harvey A. Ziessman, Janis P. O'Malley and James H. Thrall
http://interactive.snm.org/docs/pg_ch21_0403.pdf