Ultrasound of Cerebral - Cerebrovascular Index (Bilateral)
Transcranial Doppler (TCD) cerebrovascular index testing is a non-invasive ultrasound procedure that uses high-frequency sound waves to measure blood flow speed and direction in the major arteries supplying the brain on both sides of the head. Unlike many other brain imaging exams, it does not use ionizing radiation or intravenous contrast dye, and the 30-minute test requires no special preparation or fasting, with no claustrophobia risk as no enclosed scanning equipment is used.
This 30-minute non-invasive bilateral ultrasound test measures blood flow through the brain’s major cerebral arteries to assess cerebrovascular and cardiovascular health without radiation, contrast dye, or special preparation.
Key facts at a glance
- Modality
- us
- Body part
- head · cerebral
- Ionizing radiation
- false
- Radiation dose
- 0
- Duration (min)
- 30
- Pregnancy safe
- true
- Pediatric safe
- true
- Breastfeeding safe
- true
- Claustrophobia risk
- none
- Metal implant safe
- safe
- Sedation
- none
- LOINC
- 24732-1
- SNOMED
- 241475005
- Result turnaround
- 1-24h
- Availability
- routine
- Setting
- any
- Cost tier
- low
What Is a Transcranial Doppler Cerebrovascular Index Test?
A transcranial Doppler (TCD) cerebrovascular index test is a specialized vascular ultrasound that uses harmless high-frequency sound waves transmitted through the scalp and thin skull bones to assess the speed, direction, and pattern of blood flow through the major cerebral arteries on both the left and right sides of the brain. The test generates a cerebrovascular index score that helps your care team evaluate how efficiently blood is circulating to brain tissue, and it is completely painless, with no needles, incisions, radiation exposure, or contrast dye used at any point during the exam.
Clinical Applications for Cardiovascular and Cerebrovascular Care
This test is used to diagnose, monitor, and screen for a range of cardiovascular and cerebrovascular conditions, including detecting narrowed or blocked cerebral arteries caused by atherosclerosis, evaluating stroke risk in patients with heart conditions like atrial fibrillation, and monitoring for dangerous artery spasms (vasospasm) after a subarachnoid hemorrhage. It is also used to assess abnormal blood flow in patients with sickle cell disease, patent foramen ovale, and other congenital or acquired vascular abnormalities that increase risk of stroke or transient ischemic attack (TIA), and to screen for cerebrovascular issues in patients with chronic cardiovascular disease.
What to Expect During Your Exam
The 30-minute exam is performed while you are seated or lying down in a comfortable, open exam room with no enclosed scanning equipment, so there is no risk of claustrophobia. A trained sonographer will apply a water-based gel to your scalp and hold a small handheld ultrasound transducer against your temples, the back of your head, and other areas of the skull to capture blood flow data from all major cerebral arteries on both sides of your brain. You may be asked to hold your breath briefly or perform small, simple movements during the test to help the sonographer capture accurate flow measurements, and you can resume all normal activities, including driving and taking your regular medications, immediately after the exam is complete.
Preparation and Safety Information
No special preparation is required for this test: you do not need to fast, stop taking any regular medications, or arrange for transportation after the exam. The test carries no known risks, as it uses only non-ionizing sound waves (not radiation) and no contrast dye, making it safe for most patients, including those who are pregnant or have kidney disease that would prevent them from having contrast-based imaging tests.
How to read the report
- Results reviewed by radiologist.
What Is This Procedure?
This ultrasound evaluates cerebral, specifically brain. No radiation exposure.
What Does It Show?
Detailed images of brain and cerebral arteries. Part of the cardiovascular system.
Common Uses
This exam is commonly used to detect arterial blockages, evaluate blood flow, identify aneurysms, and assess vascular disease.
What to Expect
The procedure takes approximately 30 minutes.
Severe pain at procedure site
urgentWorsening severe pain with fever or other symptoms. Go to urgent care or ER.
Mild symptoms after procedure
promptMild discomfort or symptoms that don't improve. Contact your doctor.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 9, 2026. · Read our editorial policy