Normalizing fractional moving blood volume estimates with power Doppler US: defining a stable intravascular point with the cumulative power distribution function.
OBJECTIVE
To normalize the power Doppler ultrasound (US) signal to the expected signal from 100% blood in the calculation of a fractional moving blood volume estimate.


METHODS
To locate the signal from flowing blood with a consistent backscatter coefficient, the authors estimated the knee of the cumulative Doppler power distribution function. They used a flow-tube phantom to test the use of this knee to locate a radial position that would fall into a region of high shear stress and minimal rouleaux formation. They also studied how well the method normalized fractional moving blood volume estimates of the right renal cortex in a volunteer when simulating different body habitus and in a group of six healthy volunteers to estimate variability.


RESULTS
Over five flow velocities and over undersaturated to severely oversaturated receiver gains, the calculated flow-tube area was a mean 89% +/- 7 (+/- standard deviation) of a standard. In humans, the technique normalized the fractional moving blood volume estimates over an 8-dB receiver gain variation; the mean +/- standard deviation of fractional moving blood volume estimates for the six volunteers was 37.6% +/- 3.6.


CONCLUSIONS
Vascularity estimates with power Doppler US are feasible with a normalization scheme based on the cumulative Doppler power distribution function.
Rubin
J M
JM
Department of Radiology, University of Michigan Hospitals, Ann Arbor 48109, USA.
Bude
R O
RO
Fowlkes
J B
JB
Spratt
R S
RS
Carson
P L
PL
Adler
R S
RS
D000328:Adult; D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000000981:diagnostic imaging*; D001810:Blood Volume; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D018615:Ultrasonography, Doppler, Color / Q000379:methods