From dementia and neuropsychiatric problems to seizures, epilepsy and head injuries, a single-photon emission computerized tomography (SPECT) scan helps doctors diagnose and assess brain disorders. With brain SPECT images, for instance, they can tell which areas of the brain are impaired and are more or less active than others.
As with most types of nuclear imaging tests, a brain SPECT scan is a two-step procedure. In the first step, you’ll be given an intravenous injection of radioactive dye. Your brain’s more active tissues tend to retain more of the dye, so in cases of a seizure, doctors can trace which area of the brain is causing the attack. After the injection, you may be asked to wait 15 to 30 minutes (or sometimes a few hours) to ensure that the dye has been fully absorbed.
In the second step, you’ll be undergoing the actual scan. A SPECT machine fitted with a camera detects the dye and takes pictures of your brain to record the distribution of the substance. This process takes 30 minutes or so.
Pictures from the camera are forwarded to a computer and converted into 3-D brain SPECT images for analysis. The images may be in shades of gray or in color. Based on the shades or colors, your doctor can identify which areas of your brain absorbed a lot or just a bit of the dye.
In certain cases, a second brain SPECT scan may be required for comparison purposes. This incorporates Diamox, a drug that stimulates blood flow to your brain, and is usually scheduled within two to 14 days of your initial nuclear imaging scan.