A CT Scan is short for computerized axial tomography of the brain. It utilizes x-rays which are combined by a computer into a single picture. This process enables the physician to obtain a series of pictures of the brain without invading the brain itself. It is used primarily to rule out organic disease such as a tumor or bleeding in the brain as a cause of the headache problem. A CT Scan can be performed with or without dye. The dye may enhance the detection of a brain tumor or a blood clot. The dye is iodine based so it must be used with caution in those with allergy to these agents. It is more sensitive than MRI scans for detecting acute bleeding on the brain. However, the MRI scan is useful for looking at other brain conditions and takes pictures at different angles than the CT. The MRI does not use x-ray or iodine dye.
Special CT scans are done to study the paranasal sinuses. This is useful if sinusitis is suspected. A typical series of CT scans for the sinuses use less x-ray radiation than a standard complete set of x-rays. However, a CT scan of the sinuses does not show any brain tissue. Most CT scans of the head do not .include all of the sinuses.
For most problems in the brain that cause headache, MRI scans are more sensitive. For the detection of a recent brain hemorrhage or for sinus disease, CT is more helpful.
Discuss with your healthcare provider which, if any, of these tests are necessary for your headache condition.