What imaging tests are done of the brain?
- Computerized axial tomographic scan (C.T. or CAT
scan) - Uses X-rays to generate an image of the brain. Doctors use CT
to determine whether a stroke has occurred and to identify the type of
stroke: ischemic (result of blockage) or hemorrhagic (result of
bleeding). CT scanning takes from 20 minutes to an hour to complete.
- Magnetic resonance imaging scanning (M.R.I.) - The
patient is placed in a magnetic field, causing the behavior of brain
cells to change. Once the patient is in a magnetic field, the head is
subjected to bursts of energy of a known frequency. The response of the
brain cells to these bursts of energy is detected as signals that
ultimately generate an image of the brain. MRI can give very accurate
images of the brain and is used to determine the presence, location and
size of aneurysms and arteriovenous malformations, which are potential
sources for hemorrhagic stroke.
- Radionuclide angiography - Radioactive compounds are injected into a vein in the
arm; the bloodstream then carries them toward the head. As the
radioactive compound circulates in the bloodstream, it constantly emits
bursts of radiation. Once the radioactive compound reaches the brain,
these bursts of radiation are detected and used to form an image of the
brain. This imaging procedure can show areas where the brain has been
deprived of blood flow and is damaged.