What is spectral broadening?
Spectral broadening is caused by turbulence in blood flow as the normally homogeneous velocity of reflective red blood cells becomes more diverse, resulting in the apparent broadening of the spectral Doppler waveform.
What is spectral Doppler?
Definition: spectral Doppler. spectral Doppler. Instead of displaying Doppler measurements visually as in the color and power Doppler methods, spectral Doppler displays the blood flow measurements graphically, displaying flow velocities recorded over time.
What is a normal TCD?
normal flow: mean = 55cm/sec. mild: > 120cm/sec. moderate: > 160cm/sec. severe: > 200cm/sec.
What causes broadening of spectral lines?
The principal physical causes of spectral line broadening are Doppler and pressure broadening.
What causes pressure broadening?
Pressure broadening (also called collision broadening) is brought about by collisions between molecules or atoms, which can supply or remove small amounts of energy during radiative transitions, thereby allowing photons with a broader range of frequencies to produce a particular transition of a molecule.
What does less than 50% stenosis mean?
Narrowing of the carotid arteries less than 50% is considered part of normal aging. Narrowing of the carotid arteries between 50-70% carries a low risk of stroke and should be monitored.
What is CCA stenosis?
Carotid artery stenosis is a narrowing of the large arteries on either side of the neck. These arteries carry blood to the head, face, and brain. This narrowing is usually the result of a build-up of plaque within the arteries, a condition called atherosclerosis.
What is spectral analysis in ultrasound?
the association between Doppler and conventional ultrasound imaging techniques. Spectral analysis permits features of the Doppler signal to be identified which are. associated with hemodynamic phenomena, such as flow disturbance and wave reflec- tion.
What is TCD in pregnancy?
In obstetric imaging, the fetal transverse cerebellar diameter (TCD) is often measured as an additional fetal biometric parameter. It is measured as the maximal diameter between the cerebellar hemispheres on an axial scan.
What is the TCD test for?
The test examines and records the speed of the blood flow in arteries known as the Circle of Willis, which are located at the base of the brain, to facilitate the diagnosis of a wide range of conditions affecting the brain following: Subarachnoid hemorrhage (SAH) Transient Ischemic Attack (TIA) Sickle Cell Anemia.