Tests called an Indium-111 or Technetium 99m-DPTA CSF flow study, where radioactive dye is injected into the CSF, will be done to make sure the CSF flows freely throughout the spinal canal. These are done as part of the screening evaluation. If the flow study is okay, you will be eligible to take part in this study. But if there is a block of the CSF pathway, the area may be treated (usually with radiation) and then you can be re-evaluated and may still be enrolled in the study if a repeat flow study shows that the block has been cleared.