Three-dimensional ultrasound images obtained using a mechanical scanning mechanism and shown using a cube-view approach. (a) B-mode image of a kidney; (b) power Doppler image of a kidney; (c) Doppler image of the carotid arteries, showing reverse flow in the carotid sinus.
Nonlinear propagation: (a) measured pressure waveform and spectrum of a sound pulse transmitted through beef; (b) waveform and spectrum following transmission through water; and (c) measured focal beam profiles of the fundamental (solid lines) and nonlinear second harmonic beams (dashed lines). Since harmonic amplitudes are proportional to the square of the fundamental pressure, the wave passing through the relatively unattenuating water generates a disproportionate increase in the second harmonic, compared to that passing through attenuating muscle. The harmonic beam has a narrower main lobe and weaker sidelobes than the fundamental beam. From Burns, Ref. 111.
(a) Experimental apparatus used to generate the results in (b), which shows the MRI-based temperature maps (left) and contrast-enhanced T1-weighted images (right) of two sonications in two rabbit brains with (A) and without (B) preinjection of Optison®. Isotherms drawn at 3 and are superimposed on the T1-weighted images in the insets. With Optison®, the length of the focal zone was reduced, and the heating was centered at the focal plane (dotted line in the temperature images). The images were acquired parallel to the direction of the ultrasound beam. Note that in both cases a second location inferior to the first was also sonicated. In these images, the ultrasound beam propagated in a direction from left to right. (A: , , pulsed; B: , , CW). From Hynynen, Ref. 185.
Power Doppler ultrasound images of vasculature in a GEM-prostate cancer model are verified by Microfil-enhanced micro-CT. (A), from left to right in the first row, a three-dimensional power Doppler image, a three-dimensional micro-CT image, a two-dimensional plane from the three-dimensional power Doppler image, the matching two-dimensional plane from the three-dimensional micro-CT image, and an overlay of the two-dimensional power Doppler and micro-CT images of a tumor. Second and third rows, equivalent sequences of images from a tumor and tumor, respectively. Arrows, sites used for registration of corresponding vessels. Bars, . (B), bar graphs of internal and peripheral vascularity estimated from the three-dimensional power Doppler and micro-CT images shown in (A). The power Doppler and micro-CT vascularity metrics (CPD and vascular density, respectively) are shown on separate graphs. Adapted from Xu et al. (Ref. 201).
Maximum treatment volume size allowed by heating of overlying tissues as a function of tumor depth, various body aperture sizes, given typical tissue properties. Adapted from Ref. 231.
Three-dimensional prostate images obtained with a TRUS ultrasound transducer coupled to a mechanical rotational scanning mechanism. (a) 3D TRUS image with three orthogonal views; (b) the 3D TRUS image of the prostate has been segmented; (c) 3D TRUS image of a brachytherapy patient obtained after the procedure. The image has been sliced to reveal rows of brachytherapy seeds (arrow). (d) The same image as in (c) but sliced in the coronal plane (not available using conventional TRUS imaging) revealing three rows of brachytherapy seeds (arrow). Adapted from Ref. 272, Fenster et al.
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