12/05/08 - Ommaya Flow Study

A new experience... My flow study, technically known as a cisternogram, was performed last Tuesday and Wednesday. Thursday was an optional day if the previous two days weren't successful in their results - they were. So, the flow study appointment for Thursday was canceled, but an appointment to receive my first dose of intrathecal chemotherapy was scheduled in its place. That will be a separate post...


Diagram of Gamma camera (Click to enlarge)
Back to the flow study, which was done by Moffit's Nuclear Medicine group. They injected my Ommaya Reservoir (once, at the beginning of the test) with a radioactive dye (indium 111), and then used a sophisticated piece of equipment, called a gamma camera, to track it. They did this immediately, six hours later, and 24 hours later. They had enough data from these images to determine that the flow study was successful, so a 48 hour appointment wasn't necessary, and it was canceled.


A gamma camera Similar to the one used on me
The output of the camera is not what you might think. Since it is only sensitive to radiation, the images are scattered "dots" on a plain background, although you can make out my brain and spine. When the tech was taking the image, it was white spots on a black background. It could also take up to five minutes for a proper exposure. In the outputs shown below (which I was surprised to get) the images are inverted - black dots on a white background.


Gamma camera images of my flow study
The doctors got these results and decided that the flow study was successful. What all they looked at to determine this, I don't know...