Acoustic field characterization of a clinical magnetic resonance‐guided high‐intensity focused ultrasound system inside the magnet bore

Kothapalli, Satya V. V. N.; Altman, Michael B.; Partanen, Ari; Wan, Leping; Gach, H. Michael; Straube, William L.; Hallahan, Dennis E.; Chen, Hong

doi:10.1002/mp.12412

Cited by 12 publications

(11 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the complicated procedure involved in this process has prevented many clinical MR-HIFU sites from performing the measurements. To address those issues, our previous work explored the feasibility of using the robotic positioner integrated into the HIFU table instead of an external positioning system for acoustic characterization of a clinical MR-HIFU system inside the MR bore [ 13 ]. The integrated positioner consists of five motors, allowing 3D transducer translation to scan the HIFU focus against a fixed fiber-optic hydrophone.…”

Section: Discussionmentioning

confidence: 99%

“…A detailed description of the experimental setup can be found in a prior publication [ 13 ]. A clinical MR-HIFU system (Sonalleve V2, Profound Medical Inc., Mississauga, Canada) was used in this study.…”

Section: Methodsmentioning

confidence: 99%

“…The hydrophone voltage data were converted to acoustic pressures using the manufacturer-provided calibration program based on the Fresnel formula [ 15 ]. Peak positive ( p + ) and peak negative pressures ( p − ) based on individual measurements were calculated from the mean of the maximum positive and negative pressures across the 10th to 30th cycles to avoid the ramp-up and ramp-down parts of the pressure waveform (Kothapalli et al [ 13 ]). The resulting peak positive and negative pressure maps were linearly interpolated with a factor of 10 and plotted in 2D or 3D.…”

Section: Methodsmentioning

confidence: 99%

“…Previously, we demonstrated using the integrated robotic positioner within the HIFU patient table for acoustic characterization of a clinical MR-HIFU system inside the MR bore [ 13 ]. In that method, the transducer was translated against a fiber-optic hydrophone fixed within a water tank, and pressures at different transducer positions were acquired.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A convenient, reliable, and fast acoustic pressure field measurement method for magnetic resonance-guided high-intensity focused ultrasound systems with phased array transducers

et al. 2018

Self Cite

View full text Add to dashboard Cite

BackgroundWith the expanding applications of magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU), there is an urgent need for a convenient, reliable, and fast acoustic pressure field measurement method to aid treatment protocol design, ensure consistent and safe operation of the transducer, and facilitate regulatory approval of new techniques. Herein, we report a method for acoustic pressure field characterization of MR-HIFU systems with multi-element phased array transducers. This method integrates fiber-optic hydrophone measurements and electronic steering of the ultrasound beam with MRI-assisted HIFU focus alignment to the fiber tip.MethodsA clinical MR-HIFU system (Sonalleve V2, Profound Medical Inc., Mississauga, Canada) was used to assess the proposed method. A fiber-optic hydrophone was submerged in a degassed water bath, and the fiber tip location was traced using MRI. Subsequently, the nominal transducer focal point indicated on the MR-HIFU therapy planning software was positioned at the fiber tip, and the HIFU focus was electronically steered around the fiber tip within a 3D volume for 3D pressure field mapping, eliminating the need for an additional, expensive, and MRI-compatible 3D positioning stage. The peak positive and negative pressures were measured at the focus and validated using a standard hydrophone measurement setup outside the MRI magnet room.ResultsWe found that the initial MRI-assisted HIFU focus alignment had an average offset of 2.23 ± 1.33 mm from the fiber tip as identified by the 3D pressure field mapping. MRI guidance and electronic beam steering allowed 3D focus localization within ~ 1 h, i.e., faster than the typical time required using the standard laboratory setup (~ 3–4 h). Acoustic pressures measured using the proposed method were not significantly different from those obtained with the standard laboratory hydrophone measurements.ConclusionsIn conclusion, our method offers a convenient, reliable, and fast acoustic pressure field characterization tool for MR-HIFU systems with phased array transducers.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A convenient, reliable, and fast acoustic pressure field measurement method for magnetic resonance-guided high-intensity focused ultrasound systems with phased array transducers

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Sonalleve MRgFUS system included a 256-element phased array transducer mounted to a five-axis robot positioner and located inside a modified MRI patient table. The acoustic fields generated by the phased array transducer was calibrated by a fiber optic hydrophone using our previous published method 34 . The FWHM of the axial beam and lateral beam were 12.10 mm and 1.37 mm, respectively.…”

Section: Methodsmentioning

confidence: 99%

Focused Ultrasound-enabled Brain Tumor Liquid Biopsy

Zhu

Cheng

et al. 2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

Although blood-based liquid biopsies have emerged as a promising non-invasive method to detect biomarkers in various cancers, limited progress has been made for brain tumors. One major obstacle is the blood-brain barrier (BBB), which hinders efficient passage of tumor biomarkers into the peripheral circulation. The objective of this study was to determine whether FUS in combination with microbubbles can enhance the release of biomarkers from the brain tumor to the blood circulation. Two glioblastoma tumor models (U87 and GL261), developed by intracranial injection of respective enhanced green fluorescent protein (eGFP)-transduced glioblastoma cells, were treated by FUS in the presence of systemically injected microbubbles. Effect of FUS on plasma eGFP mRNA levels was determined using quantitative polymerase chain reaction. eGFP mRNA were only detectable in the FUS-treated U87 mice and undetectable in the untreated U87 mice (maximum cycle number set to 40). This finding was replicated in GL261 mice across three different acoustic pressures. The circulating levels of eGFP mRNA were 1,500–4,800 fold higher in the FUS-treated GL261 mice than that of the untreated mice for the three acoustic pressures. This study demonstrated the feasibility of FUS-enabled brain tumor liquid biopsies in two different murine glioma models across different acoustic pressures.

show abstract

Spatiotemporally-controlled transgene expression in hydroxyapatite-fibrin composite scaffolds using high intensity focused ultrasound

Moncion

Harmon

et al. 2019

Biomaterials

View full text Add to dashboard Cite

Conventional tissue engineering approaches rely on scaffold-based delivery of exogenous proteins, genes, and/or cells to stimulate regeneration via growth factor signaling. However, scaffold-based approaches do not allow active control of dose, timing, or spatial localization of a delivered growth factor once the scaffold is implanted, yet these are all crucial parameters in promoting tissue regeneration. To address this limitation, we developed a stable cell line containing a heat-activated and rapamycin dependent gene expression system. In this study, we investigate how high intensity focused ultrasound (HIFU) can spatiotemporally control firefly luciferase (fLuc) transgene activity both in vitro and in vivo by the tightly controlled generation of hyperthermia. Cells were incorporated into composite scaffolds containing fibrin and hydroxyapatite particles, which yielded significant increases in acoustic attenuation and heating in response to HIFU compared to fibrin alone. Using 2.5 MHz HIFU, transgene activation was observed at acoustic intensities of 201 W/cm 2 and higher. Transgene activation was spatially patterned in the scaffolds by rastering HIFU at speeds up to 0.15 mm/s. In an in vivo study, a 67-fold increase in fLuc activity was

show abstract

Acoustic field characterization of a clinical magnetic resonance‐guided high‐intensity focused ultrasound system inside the magnet bore

Cited by 12 publications

References 32 publications

A convenient, reliable, and fast acoustic pressure field measurement method for magnetic resonance-guided high-intensity focused ultrasound systems with phased array transducers

A convenient, reliable, and fast acoustic pressure field measurement method for magnetic resonance-guided high-intensity focused ultrasound systems with phased array transducers

Focused Ultrasound-enabled Brain Tumor Liquid Biopsy

Spatiotemporally-controlled transgene expression in hydroxyapatite-fibrin composite scaffolds using high intensity focused ultrasound

Contact Info

Product

Resources

About