In vitro evaluation of an oscillating dual-mode ultrasound probe for sector imaging and directive therapy.
Interstitial probes have been shown as effective devices to deliver high-intensity ultrasound therapy. Here, cylindrically-focused dual-mode transducers with either one or 5-elements were characterized, and a monoelement probe was evaluated in vitro. In therapy mode, the transducers were maximally efficient (> or =70%) at 5.6 MHz with surface intensities up to 20 W/cm(2). In imaging mode, fractional bandwidths were 46% and 50+/-4% (ave+/-std) for the monoelement and 5-element transducers respectively. Axial and lateral resolutions were 0.5 mm and 1.0 mm, respectively, for both transducers as measured with a point scatterer in the focal plane. After characterization, the oscillating probe was used to image and apply therapy to porcine liver. B-mode images over a 140 degrees sector were formed before and after therapy, which was applied for 90 s at each of 5 angles separated by 20 degrees (e.g. -40 degrees , -20 degrees, 0 degrees, 20 degrees, 40 degrees) to form a composite lesion. Transducer surface intensity was 18 W/cm(2). Therapy was interrupted at 125 ms intervals to collect pulse/echo data along the therapy axes. Data were displayed in real-time as an M-mode image to monitor therapy. B-mode images adequately represented the liver tissue. M-mode image data agreed well with the formation of lesions in the liver.
Owen
N R
NR
INSERM U556, Lyon, France.
Bouchoux
G
G
Murillo
A
A
Merouche
S
S
Birer
A
A
Chapelon
J Y
JY
Berriet
R
R
Fleury
G
G
Lafon
C
C
D000162:Acoustics; D000465:Algorithms; D004582:Electronics, Medical; D004867:Equipment Design; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000473:pathology; D008962:Models, Theoretical; D009991:Oscillometry / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D014159:Transducers; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000379:methods; D018084:Ultrasonography, Interventional / Q000295:instrumentation*