Harmonic imaging increases the signal-to-noise ratio in grey-scale imaging.
With the use of ultrasound contrast agents (UCA), imaging of brain perfusi
on seems possible. The authors used an ultrasound system in connection with
a 1.8/3.6-MHz harmonic sector transducer and an acoustic densitometry unit
for quantification of ultrasound intensity in the thalamus (THAL), the tem
poroparietal white matter (TPWM), and the lateral fissure (LF). Ten millili
ters of BY963, a spherosome-air-based UCA, was injected intravenously in 12
healthy volunteers. Time-intensity curves were calculated. Mean increase o
f intensity (standard deviation [SD]), mean area under the time-intensity c
urve (AUC) from baseline (SD), and mean transit time (MTT) (SD) in the regi
on of LF, THAL, and TPWM were 2.2 +/- 1.7, 1.1 +/- 0.6, 0.9 +/- 0.9 dB and
16.7 +/- 22.7, 4.7 +/- 4.7, 3.7 +/- 6.3 as well as 11.1 +/- 3.5, 9.7 +/- 3.
1, and 11.9 +/- 8.0, respectively. There was a statistically significant di
fference for mean AUC (p = 0.02) but none comparing mean intensity increase
(p = 0.07) and MTT (p = 0.9). The authors' study indicates that different
regions of the human brain show different time-intensity curves. These resu
lts suggest that it is possible to measure parameters closely related to pe
rfusion in various regions of the adult human brain.