Vascular occlusion using focused ultrasound surgery for use in fetal medicine.
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.


CONCLUSIONS
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.
Rivens
I H
IH
Joint Department of Physics, The Royal Marsden NHS Trust, Downs Road, Sutton, Surrey SM2 5PT, UK. ian@icr.ac.uk
Rowland
I J
IJ
Denbow
M
M
Fisk
N M
NM
ter Haar
G R
GR
Leach
M O
MO
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D005263:Femoral Artery / Q000473:pathology / Q000601:surgery*; D005268:Femoral Vein / Q000473:pathology / Q000601:surgery*; D005333:Fetus / Q000601:surgery; D019786:Gadolinium DTPA / Q000008:administration & dosage; D007091:Image Processing, Computer-Assisted; D007275:Injections, Intravenous; D008279:Magnetic Resonance Imaging; D008297:Male; D010865:Pilot Projects; D011673:Pulsatile Flow / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000502:physiology; D014464:Ultrasonic Therapy / Q000295:instrumentation / Q000379:methods*; D014654:Vascular Patency / Q000502:physiology
D003287:Contrast Media; D019786:Gadolinium DTPA