Transcranial doppler tcd also known as transcranial color coded duplex sonography tccs is a sonographic study of intracranial structures and blood vessels used most commonly to identify the hemodynamic state present in the vertebrobasilar circulation and the circle of willis. Transcranial doppler transcranial doppler also known as transcranial color coded duplex sonography is a non invasive painless ultrasound technique that uses high frequency sound waves to measure both the direction and velocity of the blood flow in the major cerebral arteries of the brain 1 some may refer to the imaging modality as transcranial color coded duplex sonography tccs and the . Transcranial doppler is also an ultrasound doctors use it to check how blood moves through the brain it can help them check on conditions that can affect blood flow there such as stenosis and