Study Type, Agent, and Dose?
After 3 hours

After 24 hours

Normal ¹¹¹In-DTPA Cisternogram
Agent: ¹¹¹In-Diethylenetriamine Pentaacetic (DTPA)
Adult Doses: 500 to 800 microCi intrathecally 
Critical Organ: Spinal Cord
Notes:

• Activity should reach the basal cisterns by 2 to 4 hours in adults
• Activity should appear over the convexities of the brain by 24-28 hours; if it does not, further delayed imaging is necessary
• Activity within the lateral ventricles at any time is considered abnormal
• ^99mTc-DTPA is not used to evaluate CAF flow because of its short (6 hours). T_1/2