RADIONUCLIDE CISTERNOGRAPHY

INDICATIONS:

1. Diagnosis of normal pressure hydrocephalus.
2. Identification of cerebrospinal fluid (CSF) leaks.

PATIENT PREPARATIONS:

None.

RADIOPHARMACEUTICAL:

In-111-DTPA, Dose: .500 mCi (requires 24 hrs advance notice)

Technique of administration:

1. Intrathecal via lumbar puncture (performed by referring physician or consulting service).
2. 22 gauge or smaller needle preferred to minimize CSF leakage.
3. May use 3 way stopcock so that injection of radiopharmaceutical can be followed by 1-2 mL saline flush.
4. Keep patient horizontal for 2 hours following lumbar puncture to minimize chances of headache from CSF leakage.

SCANNING TIME:

Initial lumbar puncture: 30 minutes.

Delayed images at 4 and 24 hours: 30 minutes for each set of images. (Delayed images may be needed at 48 hours and 72 hours.)

OTHER CONSIDERATIONS:

Quantitative diagnosis of CSF rhinorrhea:

1. Immediately before the intrathecal injection of the radiopharmaceutical, anterior and posterior pledgets are placed in each nostril by a physician.
2. 6 hours after placement the pledgets are removed.
3. 5 mL of venous blood is withdrawn into a heparinized tube both at time of placement and at the time of removal of the pledgets.
4. The radioactivity in each pledget and each 0.5 mL plasma sample is measured in a well counter.
5. The results are expressed as the ratio of pledget radioactivity over the average plasma radioactivity. Normal pledget to plasma radioactivity ratios do not exceed 1:3.