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

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Temperature change resulting from 120 s FUS heating and 30 s cooling with a flow rate of 40 mL/min. Areas of increased cooling (blue) are likely locations of discrete vasculature.
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Figure 3: Temperature change resulting from 120 s FUS heating and 30 s cooling with a flow rate of 40 mL/min. Areas of increased cooling (blue) are likely locations of discrete vasculature.

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
Temperature change resulting from 120 s FUS heating and 30 s cooling with a flow rate of 40 mL/min. Areas of increased cooling (blue) are likely locations of discrete vasculature.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Temperature change resulting from 120 s FUS heating and 30 s cooling with a flow rate of 40 mL/min. Areas of increased cooling (blue) are likely locations of discrete vasculature.
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.