What Is Transcranial Doppler Ultrasound?
Transcranial Doppler (TCD) is a well-known cerebral blood flow examination. It uses pulsed Doppler technology and 2MHz transmission frequency to allow the ultrasound sound beam to penetrate the thinner part of the skull and directly trace the brain. The Doppler signal of the bottom arterial blood flow is used to obtain the hemodynamic parameters of the cerebral arteries to reflect the cerebral vascular function status.
Transcranial Doppler ultrasound
Right!
- Transcranial Doppler (TCD) is well known
- 1. diagnosis
- (1) Blood flow velocity: The blood flow velocity reflects the size of the cerebral arterial lumen and blood flow. When the blood flow is constant, the blood flow velocity is inversely proportional to the size of the lumen.
- (2) Pulse index: reflects the size of peripheral resistance of cerebral blood vessels. The larger the value, the greater the peripheral resistance of the cerebrovascular system, and vice versa.
- (3) Audio signal and spectrum waveform: reflect the local blood flow state of cerebral blood vessels.
- The local blood flow velocity in the stenosis is accelerated or there is a large bilateral difference.
- The vascular motion in the area after stenosis is reduced.
- Abnormal blood flow in any area that causes spectrum widening.
- The increased local blood flow velocity in the posterior or anterior communicating arteries indicates collateral circulation.
- Lumen stenosis caused by cerebral vasospasm: if the blood flow velocity increases by 50% after subarachnoid hemorrhage or the middle cerebral artery blood flow velocity reaches 120 cm / s (cm / s).
- Transcranial Doppler ultrasound can penetrate the skull without trauma, which overcomes the inaccuracy of the cerebral blood flow map during the traditional physical examination and the traumatic nature of cerebral angiography. Long-term dynamic observation, while also providing MRI, DSA, PET, SPECT and other imaging technology can not provide hemodynamic parameters, provide reference information for the diagnosis, monitoring, treatment of cerebrovascular disease, in evaluating the brain Vascular disease and differential diagnosis are of great significance.
- Transcranial Doppler ultrasound reflects the functional status of cerebral blood vessels through the following indicators.
- (1) Blood flow velocity: The blood flow velocity reflects the size of the cerebral arterial lumen and blood flow. When the blood flow is constant, the blood flow velocity is inversely proportional to the size of the lumen.
- (2) Pulse index: reflects the size of peripheral resistance of cerebral blood vessels. The larger the value, the greater the peripheral resistance of the cerebrovascular system, and vice versa.
- (3) Audio signal and spectrum waveform: reflect the local blood flow state of cerebral blood vessels.
- People's physical examination experts said: The following conditions can be considered for this test:
- Diagnosis of intracranial vascular obstruction.
- Diagnose extracranial vascular obstruction and understand whether the collateral circulation is good.
- To evaluate the effects of extracranial vascular disease (intracranial arterial stenosis, obstruction, and subclavian artery stealing blood) on intracranial blood flow velocity.
- Diagnosis and follow-up detection of internal carotid dissection aneurysms.
- Detecting and identifying the venous malformation of the arteries supplying blood.
- Evaluate the ability of the collateral circulation, and predict the clamping effect before carotid endarterectomy.
- Diagnosis of other intracranial vascular diseases: abnormal skull base vascular network disease, aneurysm, vascular dementia, carotid cavernous sinus fistula, cerebral infarction with low blood flow.
- Intermittent monitoring and follow-up study of vasospasm after subarachnoid hemorrhage, vasospasm and hyperperfusion of migraine, acute stroke, blood flow changes during anticoagulation after intracranial vascular obstruction, and changes in blood viscosity .
- Continuous monitoring. [1]