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Quantifying perfusion-related energy losses during magnetic resonance-guided focused ultrasound

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Coronal magnitude image obtained during MRgFUS heating. Fiberoptic probes measured the background temperature. The dashed line indicates the circular heating region and the solid line identifies the region of interest for data presented in figures 3 and 4.
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Figure 2: Coronal magnitude image obtained during MRgFUS heating. Fiberoptic probes measured the background temperature. The dashed line indicates the circular heating region and the solid line identifies the region of interest for data presented in figures 3 and 4.

Mentions: Experiments were performed in ex vivo porcine kidneys perfused with a heparin- H2O solution in variable flow (0, 20, 40 mL/min) situations and embedded in a gelatin phantom (Figure 1). Heating was achieved by electronically steering a phased-array ultrasound transducer (256 elements, f=1 MHz) in an 8 mm-radius circle for 120 s (Figure 2). MR temperature data (Figure 3) were acquired with a 3T Siemens Trio MRI (3D segmented-EPI, TR/TE=30/11 ms, FA=15°, EPI factor=9, 2x2x3 mm3, 3.3 s acquisition, ZFI to 0.5-mm isotropic spacing). Based on conservation of energy principles, deviation of a thermal model that excludes perfusion effects from the experimental temperatures was used to quantify Qb. Estimates of Qb were obtained at the time of each MR acquisition during cooling, transformed into perfusion values via the Pennes bioheat transfer equation,[7] and averaged to mitigate the effects of noise.


Quantifying perfusion-related energy losses during magnetic resonance-guided focused ultrasound
Coronal magnitude image obtained during MRgFUS heating. Fiberoptic probes measured the background temperature. The dashed line indicates the circular heating region and the solid line identifies the region of interest for data presented in figures 3 and 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4489705&req=5

Figure 2: Coronal magnitude image obtained during MRgFUS heating. Fiberoptic probes measured the background temperature. The dashed line indicates the circular heating region and the solid line identifies the region of interest for data presented in figures 3 and 4.
Mentions: Experiments were performed in ex vivo porcine kidneys perfused with a heparin- H2O solution in variable flow (0, 20, 40 mL/min) situations and embedded in a gelatin phantom (Figure 1). Heating was achieved by electronically steering a phased-array ultrasound transducer (256 elements, f=1 MHz) in an 8 mm-radius circle for 120 s (Figure 2). MR temperature data (Figure 3) were acquired with a 3T Siemens Trio MRI (3D segmented-EPI, TR/TE=30/11 ms, FA=15°, EPI factor=9, 2x2x3 mm3, 3.3 s acquisition, ZFI to 0.5-mm isotropic spacing). Based on conservation of energy principles, deviation of a thermal model that excludes perfusion effects from the experimental temperatures was used to quantify Qb. Estimates of Qb were obtained at the time of each MR acquisition during cooling, transformed into perfusion values via the Pennes bioheat transfer equation,[7] and averaged to mitigate the effects of noise.

View Article: PubMed Central - HTML

No MeSH data available.