In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 114, No. 4_Supplement ( 2003-10-01), p. 2321-2321
Kurzfassung:
The ability to detect small gas bubbles in blood depends on the relative magnitude of the acoustic power backscattered from the microbubbles (‘‘signal’’) to the power backscattered from the red blood cells (‘‘noise’’). Erythrocytes are weak, Rayleigh scatterers, and therefore the backscattering coefficient (BSC) of blood increases as the fourth power of frequency throughout the diagnostic frequency range. Microbubbles, on the other hand, are either resonant or super-resonant in the range 10–30 MHz. Above resonance, their total scattering cross-section remains constant with increasing frequency and the directivity pattern of the scattered wave changes significantly. Therefore, increasing the detection frequency may lead to a reduction in signal-to-noise ratio. An active cavitation detector (ACD) was utilized to observe the gradual obscuring of a steel target in blood with increasing frequency, and to measure the BSC of suspensions of Optison® microspheres in blood, as a function of microsphere concentration, hematocrit and frequency in the range 10–30 MHz. The experimental results were compared with theoretical predictions of the BSC of Optison® and blood, in order to determine whether the presence of tightly packed red blood cells affects the acoustic response of the microbubbles. [Work supported by the ASA, the US Army, and the NSF.]
Materialart:
Online-Ressource
ISSN:
0001-4966
,
1520-8524
Sprache:
Englisch
Verlag:
Acoustical Society of America (ASA)
Publikationsdatum:
2003
ZDB Id:
1461063-2
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