Blockage of carotid arteries show no warning signs before symptoms of a stroke or transient ischemic attack, says WebMD, but several tests can pinpoint clogging in advance, starting with a stethoscope examination. More tests include ultrasound, cerebral angiography, CT or MR angiography, CT scan and MRI.
A preliminary physical exam for carotid artery blockage involves listening for a bruit in the neck through a stethoscope. The whooshing sound of a bruit signifies turbulence of flow caused by the narrowing of an artery, says Mayo Clinic and MedicineNet. A standard or Doppler carotid ultrasound is a non-invasive procedure showing blood flow and exposing plaque or blood clots with the use of high frequency sound waves.
Tests often use a dye that is injected into the veins as a contrast material for better imaging results. CT angiography uses X-rays, like a CT scan, to take pictures of the body from multiple angles. A computer then creates visual cross sections of the carotid arteries.
MRI and MR angiography use a powerful magnet as an imaging technique, according to WebMD. Because of the magnet, patients with certain implants, such as pacemakers, cannot undergo these tests. Otherwise, it is very safe. A riskier procedure would be cerebral angiography, which is a standard for observing carotid arteries. Although invasive, it allows observation of a contrast dye moving through the arteries in real time on a live X-ray screen.