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Vascular occlusion using focused ultrasound surgery for use in fetal medicine
I H Rivens1, I J Rowland, M Denbow
1Joint Department of Physics, The Royal Marsden NHS Trust, Downs Road, Sutton, Surrey SM2 5PT, UK. ian@icr.ac.uk
Objective:
Focused ultrasound surgery (FUS) is being developed clinically for the non-invasive treatment of soft tissue tumours of the prostate, bladder, liver, kidney, muscle and breast. In the work described in this paper, the application of FUS is extended to investigate the potential to induce vascular occlusion, with the aim of applying the technique to problems in fetal medicine and oncology.
Methods:
In this feasibility study the occlusion of femoral blood flow in vivo is demonstrated using an array of multiple single exposures of 1.7 MHz focused ultrasound. These were placed in two rows of four lesions at a focal depth of 5 mm. The 4660-W cm-2 (free field spatial peak intensity) 2-s exposures were placed 2 mm apart. Vascular patency was assessed using a Siemens Vision (1.5T) magnetic resonance (MR) imaging scanner with an extremity coil, and intravenous gadolinium contrast agent. FLASH and FISP MR sequences were used to obtain full 3D data sets providing information on soft tissue damage and perfusion.
Results And Conclusion:
Total vascular occlusion was achieved in four of nine cases and significant vascular disruption in five of nine cases. Refinement of the FUS technique and long-term studies are now indicated prior to initial clinical application in fetal medicine.
Insights
Focused ultrasound surgery (FUS) shows promise for inducing vascular occlusion in vivo. This non-invasive technique could be applied to fetal medicine and oncology, with further refinement needed for clinical use.
Area of Science:
- Medical Imaging and Ultrasound Technology
- Vascular Biology and Intervention
Background:
- Focused ultrasound surgery (FUS) is an emerging non-invasive treatment for soft tissue tumors.
- Current applications target organs like the prostate, liver, and breast.
- This study explores FUS for inducing vascular occlusion.
Purpose of the Study:
- To investigate the feasibility of using FUS to create vascular occlusion.
- To assess the potential application of FUS in fetal medicine and oncology.
- To evaluate FUS-induced vascular occlusion in a preclinical model.
Main Methods:
- Femoral artery occlusion in vivo using multiple 1.7 MHz FUS exposures.
- Exposures delivered in two rows of four lesions at 5 mm depth, 2 mm apart.
- Vascular patency assessed via 1.5T MRI with gadolinium contrast, using FLASH and FISP sequences.
Main Results:
- Complete vascular occlusion achieved in 4 out of 9 cases.
- Significant vascular disruption observed in 5 out of 9 cases.
- MRI provided detailed soft tissue damage and perfusion data.
Conclusions:
- FUS can induce vascular occlusion in vivo.
- The technique shows potential for fetal medicine applications.
- Further refinement and long-term studies are necessary before clinical translation.