Brain tumor imaging

Indications:

Detection of recurring brain tumors

Localization of recurring brain tumors

radiation necrosis from recurrent high-grade tumor and high-grade from low-grade gliomas

Contraindications:
Patient may be to agitated or uncooperative to remain still for acquisition


Questions asked in Patient History:

List the common questions asked when taking a patient history for this specific procedure.
Any known head/neck trauma?
Any known plates?
Radiopharmaceutical information:
  • Radionuclide: Tc-99m, Thallium
  • Radiopharmaceutical: Tl-201 and Tc-99m Sestamibi,
  • Adult dosing: 2-4 mCi Tl-201 OR 20 mCi Sestamibi
  • Pediatric dosing:
  • Method of administration: Intravenousl
  • Method of Localization:
  • Physical Half-life: Tc-99m Sestamibi 6 hrs, Tl-201 72 hours

Patient Preparation:
1- verify order, establish pt ID
2- explain procedure to the pt
3- Restriction of any alcohol, caffiene, abd nicotine 24 hours prior to injection
4- Place patient in a quiet, dimly lit room
5- After injection, patient is advised to remain supine, and lay still 1 hour prior to imaging.



Side Effects:

No side effects

Equipment Used:
Type of Camera or Probe: large FOV
Collimator used: LEAP or LEHR

Acquisition Setup:

Photopeak(s): Tc-99m Sestamibi 140 KeV; Tl-201 ~70-80 keV

Window(s): 20%


Dynamic: View(s)
Matrix:
Time/Frame:
Number of Frames:

Statics: View(s)
Matrix:
Total Counts or Duration: 200,000 - 800,000 counts

Whole body: View(s)
not needed

SPECT:
180 or 90 degree configuration
Total Rotation: 180 or 360
Starting point:
Matrix: 128 x 128
Time/Azmuiths: 40 seconds
Number of Azmuiths: 40 per head

Processing:

Filtered backprojection or iterative reconstruction
Filter: Hamming
Cut-off: 1.2
Frequency: high


Procedure:
  • Inject dose: Intravenously
  • 2-4 mCi Tl-201
  • 20 mCi Tc-99m Sestamibi
  • Image 20-30 minutes post administration
  • 2 hour delayed Tl-201 images may be helpful
  • because abnormal tissue would washout slower than normal brain areas of BBB distribution
  • position patient so the brain is entirely in the FOV
  • Position collimators as close as possible to the head
  • Begin imaging
Normal Uptake and common varients:

Tl-201 is an analog to potassium. The distribution of this radiopharmacuetical depends on blood flow, and metabolic activity as a result of the sodium potassium pump.
Tc-99m sestamibi is carried into the endothelial cells to the mitochondria. Tc-99m Sestamibi also accumulates in the choroid plexus.

Abnormal Uptake and causes:
Abnormal tumor tissue has a tendency to clear at a slower pace than normal tissues;

photo.JPG

Artifacts:
infections, intracranial abscess can create false positive in a study.

References: