High frequency, high frame-rate ultrasound imaging system

1. A scanhead for use with an ultrasound imaging system, comprising:

a transducer assembly comprising a single element ultrasonic transducer that is configured to generate ultrasound at a frequency of at least 20 megahertz (20 MHz), to transmit at least a portion of the generated ultrasound into a subject and to receive ultrasound energy from the subject;

an elongate member having a proximal end, wherein the elongate member is configured to pivot about a pivot axis spaced from the proximal end, and wherein the transducer assembly is non-rotatably coupled to the proximal end of the elongate member;

a means for oscillating the transducer along a reciprocating convex arcuate path at a frequency of at least 7.5 Hz, wherein a portion of the means for oscillating is fixed relative to the elongate member and moves along a reciprocating arcuate route remote from the reciprocating arcuate path of the transducer such that movement of the portion of the means for oscillating causes a complementary and opposite movement of the transducer, and wherein the reciprocating arcuate path of the transducer is co-planer to the reciprocating arcuate route of the portion of the means for oscillating; and

a means for sensing the spatial position of a proximal end of the portion of the means for oscillating along the reciprocating Arcuate route to determine the position of he transducer along its arcuate path.

2. The scanhead of claim 1 , wherein the transducer is a broadband transducer.

3. The scanhead of claim 1 , wherein the transducer assembly and at least a portion of the elongate member are located within an enclosed volume, and wherein the enclosed volume is at least partially filled with a fluid.

4. The scanhead of claim 3 , wherein the fluid has an impedance substantially similar to the impedance of tissue.

5. The scanhead of claim 3 , wherein the fluid is a glycol.

6. The scanhead of claim 3 , wherein the fluid is water.

7. The scanhead of claim 3 , wherein the fluid is selected from the group consisting of: water, ethylene glycol, triethylene glycol, and light paraffin oil.

8. The scanhead of claim 3 , wherein the enclosed volume is partially defined by an acoustically penetrable membrane and wherein the acoustically penetrable membrane is positioned such that at least a portion of the generated ultrasound can pass therethrough the membrane before being transmitted into the subject.

9. the scanhead of claim 8 , further comprising a sealing membrane that defines at least a portion of the enclosed volume.

10. the scanhead of claim 9 , wherein the sealing membrane is sealed relative to the elongate member at the pivot axis.

11. the scanhead of claim 10 , wherein the sealing membrane is configured to have a reduced stretch deformation when the elongate member is oscillated within the enclosed volume.

12. The scanhead of claim 9 , wherein the sealing membrane comprises a flexible elastomer.

13. The scanhead of claim 9 , wherein the sealable membrane comprises a flexible elastomer.

14. The scanhead of claim 8 , wherein the acoustically penetrable membrane has a thickness of about 0.9 microns (μm) to about 60.0 microns (μm).

15. The scanhead of claim 8 , wherein the acoustically penetrable membrane is sealably attached to a frame member, and wherein the frame member and the membrane comprise the same material.

16. The scanhead of claim 8 , wherein the acoustically penetrable membrane has an acoustic impedance that is substantially the same as the acoustic impedance of the fluid.

17. The scanhead of claim 8 , wherein the acoustically penetrable membrane has an impedance of between about 1.0 megaRayles and 3.3 megaRayles.

18. The scanhead of claim 17 , wherein the acoustically penetrable membrane has an impedance of between about 1.5 megaRayles and 1.8 megaRayles.

19. The scanhead of claim 8 , wherein the acoustically penetrable membrane comprises a material selected from the group consisting of: polyester, polycarbonate, acrylic, thermoplastic elastomer, silicone elastomer, laytex elastomer, Surlyn® ionomer, Surlyn® 8940, Kapton®, polymethyl pentene, TPX® MX-002, TPX® 95, MX-004; Teflon®, Mylar®, polyethylene, polytetrafluoroethylene, polycarbonate, polypropylene, and polyurethane films.

20. The scanhead of claim 19 , wherein the polyethylene is low density polyethylene (LDPE).

21. The scanhead of claim 8 , wherein at least a portion of the transducer can contact at least a portion of the interior surface of the membrane during its movement along the reciprocating arcuate path.

22. The scanhead of claim 1 , wherein the transducer can be moved along the reciprocating arcuate path over a distance of about 15 millimeters (mm) or less.

23. The scanhead of claim 1 , wherein the transducer can be moved along the reciprocating arcuate path over a distance of about 10 millimeters (mm) or less.

24. The scanhead of claim 1 , wherein the transducer can be moved along the reciprocating arcuate path over an angle of about 22 degrees or less.

25. The scanhead of claim 1 , wherein the transducer can be moved along the reciprocating arcuate path at a frequency of at least 15 Hz.

26. The scanhead of claim 1 , wherein the transducer can be oscillated along the reciprocating arcuate path at a frequency of at least 30 Hz.

27. The scanhead of claim 1 , further comprising a position encoder configured to determine the position of the transducer along its reciprocating arcuate path.

28. The scanhead of claim 27 , wherein the position encoder is configured such that the position of the transducer can be accurately tracked along the reciprocating arcuate path to within about 1.0 micron (μm) of the actual transducer position.

29. The scanhead of claim 1 , wherein the means for oscillating comprises a limited angle motor.

30. The scanhead of claim 29 , wherein the limited angle motor is a moving coil type torque motor.

31. The scanhead of claim 29 , wherein the limited angle motor can oscillate the transducer along the reciprocating arcuate path at a speed of at least about 10 Hz.

32. The scanhead of claim 31 , wherein the limited angle motor can oscillate the transducer along the reciprocating arcuate path at a speed of at least about 15 Hz.

33. The system of claim 32 , wherein the limited angle motor can oscillate the transducer along the reciprocating arcuate path at a speed of at least about 30 Hz.

34. The scanhead of claim 1 , wherein the transducer is configured to generate ultrasound at a frequency of between about 25 MHz and about 60 MHz.

35. The scanhead of claim 1 , wherein the transducer is configured to generate ultrasound at a frequency of at least about 25 MHz.

36. An ultrasound imaging system, comprising:

the scanhead of claim 1 ; and

a processor configured to process the received ultrasound to provide an image having a frame rate of at least 15 frames per second (fps).

37. The system of claim 36 , wherein the processor is further configured to produce an ultrasound image having a spatial resolution of less than about 100 microns (μm).

38. The system of claim 37 , wherein the processor is further configured to produce an ultrasound image having a spatial resolution of about and between 75-100 microns (μm).

39. The system of claim 37 , wherein the processor is further configured to produce an ultrasound image having a spatial resolution of about and between 30-100 microns (μm).

40. The system of claim 36 , wherein the transducer can be oscillated along the reciprocating arcuate path at a frequency of at least 15 Hz, and wherein the processor is configured to provide an image having a frame rate of at least 30 fps and a spatial resolution of less than about 100 microns (μm).

41. The system of claim 36 , wherein the transducer can be oscillated along the reciprocating arcuate path at a frequency of at least 30 Hz and wherein the processor is configured to provide an image having a frame rate of at least 60 fps and a spatial resolution of less than about 100 microns (μm).

42. The ultrasound imaging system of claim 1 , wherein the scanhead is configured for extra-vascular imaging applications.

43. An ultrasound imaging system, comprising:

the scanhead of claim 1 ;

a processor configured to process the received ultrasound to provide an image having a frame rate of at least 15 frames per second (fps); and

a means for positioning the transducer to within about 1 micron (μm) of a predetermined location along the reciprocating arcuate path.

44. The ultrasound imaging system of claim 43 , wherein the processor is further configured to provide a pulsed-wave Doppler image.

45. The ultrasound imaging system of claim 43 , wherein the processor is further configured to provide an M-Mode image.

46. A method for producing an ultrasound image, comprising:

a) providing a scanhead, comprising:

i) a transducer assembly comprising a single element ultrasonic transducer;

ii) an elongate member having a proximal end, wherein the elongate member is configured to pivot about a pivot axis spaced from the proximal end, and wherein the transducer assembly is non-rotatably coupled to the proximal end of the elongate member;

iii) a means for oscillating the transducer along a reciprocating convex arcuate path, wherein a portion of the means for oscillating is fixed relative to the elongate member and moves along a reciprocating arcuate route remote from the reciprocating arcuate path of the transducer such that movement of the portion of the means for oscillating causes a complementary and opposite movement of the transducer, and wherein the reciprocating arcuate path of the transducer is co-planer to the reciprocating arcuate route of the portion of the means for oscillating; and

iv) a means for sensing the spatial position of a proximal end of the portion of the means for oscillating along the reciprocating Arcuate route to determine the position of the transducer along its arcuate path.

b) generating ultrasound at a frequency of at least about 20 megahertz (20 MHz) using the transducer;

c) transmitting at least a portion of the generated ultrasound into a subject from a location external to the subject;

d) receiving ultrasound energy from the subject;

e) oscillating the transducer along the reciprocating arcuate path at a frequency of at least 7.5 Hz during the generation, transmission and receipt of the ultrasound; and

f) processing the received ultrasound to provide an image having a frame rate of at least 15 frames per second (fps).

47. The method of claim 46 , wherein the subject is a small animal.

48. The method of claim 47 , wherein the small animal is a mouse or a rat.

49. The method of claim 46 , wherein the subject is an embryo.

50. The method of claim 46 , further comprising using ultrasound in a frequency range of 20 MHz to 60 MHz.

51. The method of claim 46 , wherein the transducer is moved along the reciprocating arcuate path at a frequency of at least 30 Hz, and wherein the provided image has a frame rate of at least 60 fps.

52. The method of claim 46 , wherein the position of the transducer is accurately tracked along the reciprocating arcuate path to within about 1.0 micron (μm) of the actual transducer position using a position encoder.

53. The method of claim 46 , further comprising positioning the transducer to within about 1 micron (μm) of a predetermined location along the reciprocating arcuate path.

54. The method of claim 53 , wherein the provided image is a pulsed-wave Doppler image.

55. The method of claim 53 , wherein the provided image an M-Mode image.