Ultrasound imaging with acquisition of imaging data in perpendicular scan planes

• US 6,537,220 B1
• Filed: 08/31/2001
• Issued: 03/25/2003
• Est. Priority Date: 08/31/2001
• Status: Expired due to Fees

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Emery, Charles Dale, Friemel, Barry Hugh
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US09/944,650
• Publication Number:
  US 20030055308A1
• Time in Patent Office: 571 Days
• Field of Search: 600/437, 600/443, 600/447, 600/459, 128/916
• US Class Current: 600/447
• CPC Class Codes: A61B 8/14 Echo-tomography
• CPC Class Codes: A61B 8/145 characterised by scanning multiple planes
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: B06B 1/0629 Square array
• CPC Class Codes: G01S 15/8925 the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems
• CPC Class Codes: G10K 11/30 using refraction, e.g. acoustic lenses

Abstract

An ultrasonic imaging array has two independent, interleaved linear subarrays occupying a common array face. The subarrays are independently steerable and focusable in different imaging planes. The subelements making up the elements in of the subarrays is preferably quadrilateral. Adjacent subelements in each element are electrically connected via an interconnect portion such that the interconnect portion connecting each pair of adjacent subelements in each element is substantially linear and is aligned with the diagonals of the adjacent subelements. A preferred acoustic lens is curved in both azimuth and elevation directions, whereby the subarrays are independently focusable. By transmitting in one plane and simultaneously receiving in a different, orthogonal plane, a system including the array can image a 3-D region of interest (ROI). In a volumetric embodiment of the invention two orthogonal B-mode images of a structure within the ROI are displayed simultaneously. The user may then trace the outlines of the images and the system therefrom calculates the volume of the structure.

Claims

1. An ultrasonic imaging array comprising two independent, interleaved linear subarrays occupying a common array face, the subarrays being independently steerable and focusable in different imaging planes in which:

each subarray comprises a plurality of elements and each element comprises at least one subelement;

each subelement is quadrilateral and has a diagonal;

adjacent subelements in each element are electrically connected via an interconnect portion; and

the interconnect portion connecting each pair of adjacent subelements in each element is substantially linear and is aligned with the diagonals of the adjacent subelements.

2. An array as defined in claim 1, in which:

the diagonals of all subelements in each element are aligned; and

the interconnect electrically connecting the subelements in each element is linear over the extent of the array face.

3. An array as defined in claim 2, further comprising a multilayer flex circuit, in which:

the interconnects for a first one of the subarrays are patterned as first linear traces onto a first separate layer of the flex circuit and extend to a first edge of the array face; and

the interconnects for a second one of the subarrays are patterned as second linear traces onto a second separate layer of the flex circuit and extend to a second edge of the array face that is different from the first edge.

4. An array as defined in claim 3, further comprising a connector for each subarray, the connector for each subarray being connected to the interconnects of the respective subarray along the respective edge.

5. An array as defined in claim 2, in which:

the subelements in each element are grouped into a plurality of groups, the groups in each element of each respective subarray having the same relative position within the subarray;

the subelements in each group are electrically connected;

whereby each subarray operates as a multidimensional array, with a dimension greater than one and less than two.

6. An array as defined in claim 5, in which a first group consists of a central plurality of subelements and a second group consists of the plurality of subelements located on either side of the first group.

7. An array as defined in claim 1, comprising first and second subelements, in which:

the first subelements comprise a first one of the subarrays;

the second subelements comprise a second one of the subarrays;

edges of the subelements extend in a first and a second direction; and

the first and second subelements are arranged in a pattern in which they alternate in both the first and second directions.

8. An array as defined in claim 1, in which each subarray constitutes an independent, unswitched aperture.

9. An array as defined in claim 1, further comprising an acoustic lens mounted over the array face, which defines a single, common aperture, in which:

each subarray comprises a plurality of elements;

the elements in a first one of the subarrays extend in an azimuth direction and the elements in a second one of the subarrays extend in an elevation direction, which is orthogonal to the azimuth direction; and

the lens is curved in both the azimuth and elevation directions, whereby the subarrays are independently focusable.

10. An array as defined in claim 9, in which curvatures of the lens have radii substantially proportional to the following:

$\frac{1}{f_{\mathrm{gx}}}=\left(\frac{v_{\mathrm{lens}}-v_{\mathrm{water}}}{v_{\mathrm{lens}}}\right)<br><br>\left(\frac{1}{R_x}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{1}{f_{\mathrm{gy}}}=\left(\frac{v_{\mathrm{lens}}-v_{\mathrm{water}}}{v_{\mathrm{lens}}}\right)<br><br>\left(\frac{1}{R_y}\right)$

where f_gx is the geometric focus in the azimuth-dimension;

R_x is the lens radius of curvature in the azimuth-dimension;

f_gy is the geometric focus in the elevation-dimension;

R_y is the lens radius of curvature in the elevation-dimension;

v_lens is the velocity of sound in the lens; and

v_water is the velocity in water.

11. An array as defined in claim 10, in which the lens has a thickness substantially proportional to the following:

$\mathrm{\Delta <br><br>}=C-\frac{v_{\mathrm{lens}}}{v_{\mathrm{water}}}<br><br>\left(\sqrt{z_x^2+x^2}+\sqrt{z_y^2+y^2}\right)$

where Δ

=Δ

(x,y) is the thickness of the lens at each point (x,y), where x is an azimuth coordinate and y is an elevation coordinate;

C is a constant; and

z_x and z_y are focal distances in a depth direction that is orthogonal to the azimuth and elevation directions.

12. An array as in claim 1, in which the subelements are diced from ceramic and are convex-concave, that is, curved in both the first and second dimensions, the first and second directions being orthogonal, whereby the subarrays may be focused in both the first and second directions.

13. A method for imaging a region of interest of a body using ultrasound, in which the, region of interest includes a body structure, comprising:

activating and independently steering in different imaging planes interleaved linear subarrays of ultrasound-generating elements occupying a common face of an ultrasound array;

receiving echo signals from within the region of interest along the different imaging planes;

generating from the received echo signals and simultaneously displaying for a user two orthogonal cross-sectional B-mode images of the region of interest;

moving the array to a plurality of positions;

at each position, tracing a periphery of the body structure as displayed in a first one of the orthogonal cross-sectional B-mode images;

measuring distance of movement of the array as a function of sequentially generated second ones of the B-mode images, which are orthogonal to the first B-mode images; and

calculating a volume of the structure as a function of the products of areas within the traced periphery and the corresponding measured distances, summed over all the positions of the array.

14. An ultrasonic imaging system comprising:

an ultrasound transducer having two independent, interleaved linear subarrays occupying a common array face;

transmission control means for activating and independently steering the subarrays in different imaging planes;

reception means for receiving echo signals from insonified points within a region of interest and for converting the received echo signals into a predetermined display format; and

display means for displaying the converted echo signals in which;

each subarray comprises a plurality of elements and each element comprises at least one subelement;

each subelement is quadrilateral and has a diagonal;

adjacent subelements in each element are electrically connected via an interconnect portion; and

the interconnect portion connecting each pair of adjacent subelements in each element is substantially linear and is aligned with the diagonals of the adjacent subelements.

15. A system as in claim 14, further comprising:

processing means for independently generating two orthogonal cross-sectional B-mode images of a region of interest;

the display means being further provided for simultaneously displaying the two orthogonal cross-sectional B-mode images for a user.

16. A system as in claim 15, further comprising:

input means maneuverable by the user for tracing a periphery of a body structure as displayed in a first one of the orthogonal cross-sectional B-mode images;

volume calculation means for measuring distance of movement of the array as a function of sequentially generated second ones of the B-mode images, which are orthogonal to the first B-mode images and for calculating a volume of the structure as a function of the products of areas within the traced periphery and the corresponding measured distances, summed over a plurality of positions of the array.

17. An ultrasonic imaging array comprising two independent, interleaved linear subarrays occupying a common array face, in which:

each subarray comprises a plurality of elements and each element comprises at least one subelement;

each subelement is quadrilateral and has a diagonal;

adjacent subelements in each element are electrically connected via an interconnect portion;

the interconnect portion connecting each pair of adjacent subelements in each element is substantially linear and is aligned with the diagonals of the adjacent subelements;

the diagonals of all subelements in each element are aligned;

the first subelements comprise a first one of the subarrays;

the second subelements comprise a second one of the subarrays;

edges of the subelements extend in a first and a second direction; and

the first and second subelements are arranged in a pattern in which they alternate in both the first and second directions; and

the interconnect electrically connecting the subelements in each element is linear over the extent of the array face;

whereby each subarray constitutes an independent, unswitched aperture, the subarrays being independently steerable and focusable in different imaging planes.

18. An ultrasonic system for volumetric measurement comprising:

an ultrasound transducer having two independent, interleaved linear subarrays occupying a common array face;

transmission control means for independently activating and independently steering the subarrays in different imaging planes;

reception means for receiving echo signals from insonified points within a region of interest and for converting the received echo signals into a predetermined display format;

processing means for independently generating two orthogonal cross-sectional B-mode images of a region of interest;

display means for displaying the converted echo signals and for simultaneously displaying the two orthogonal cross-sectional B-mode images for a user;

input means maneuverable by the user for tracing a periphery of a body structure as displayed in a first one of the orthogonal cross-sectional B-mode images;

volume calculation means for measuring distance of movement of the array as a function of sequentially generated second ones of the B-mode images and for calculating a volume of the structure as a function of the products of areas within the traced periphery and the corresponding measured distances, summed over a plurality of positions of the array.

19. An acoustic lens for an ultrasound array, which has elements extending both an azimuth direction an elevation direction, which is orthogonal to the azimuth direction, the lens being curved in both the azimuth and elevation directions;

in which curvatures of the lens have radii substantially proportional to the following;

$\frac{1}{f_{\mathrm{gx}}}=\left(\frac{v_{\mathrm{lens}}-v_{\mathrm{water}}}{v_{\mathrm{lens}}}\right)<br><br>\left(\frac{1}{R_x}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{1}{f_{\mathrm{gy}}}=\left(\frac{v_{\mathrm{lens}}-v_{\mathrm{water}}}{v_{\mathrm{lens}}}\right)<br><br>\left(\frac{1}{R_y}\right)$

where f_gx is the geometric focus in the azimuth-dimension;

R_x is the lens radius of curvature in the azimuth-dimension;

f_gy is the geometric focus in the elevation-dimension;

R_y is the lens radius of curvature in the elevation-dimension;

V_lens is the velocity of sound in the lens; and

v_water is the velocity in water.

20. A lens as defined in claim 19, in which the lens has a thickness substantially proportional to the following:

$\mathrm{\Delta <br><br>}=C-\frac{v_{\mathrm{lens}}}{v_{\mathrm{water}}}<br><br>\left(\sqrt{z_x^2+x^2}+\sqrt{z_y^2+y^2}\right)$

where Δ

=Δ

(x,y) is the thickness of the lens at each point (x,y), where x is an azimuth coordinate and is an elevation coordinate;

C is a constant; and

Z_x and z_y are focal distances in a depth direction that is orthogonal to the azimuth and elevation directions.