Abstract:
Provided herein are devices and methods for mounting variously configured medical imaging probes for imaging applications. In one aspect, a holding device allows for interfacing/holding most conventional ultrasound probes such that the probes may be attached to a positioning device using a common interface. As ultrasound probes come in various sizes and lengths, the device may adjust to different lengths, widths and shapes of different probes. Hence, the device may work in a substantially universal manner while securely holding probes with little wobble or other problems.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. 119 to U.S. Provisional Application No. 60/893,317, entitled: “UNIVERSAL HOLDER,” filed on Mar. 6, 2007, and No. 60/894,602, entitled: “CRADLE WITH MANUAL RATCHET,” filed on Mar. 13, 2007, the contents of which are incorporated herein as if set forth in full. 
    
    
     FIELD OF INVENTION 
     The present invention is directed to an apparatus for holding and positioning a medical imaging instrument. More particularly, the invention relates to an apparatus adapted to hold a plurality of differently configured medical imaging instruments such that those instruments may be secured and/or rotated about at least one fixed axis. 
     BACKGROUND OF THE INVENTION 
     Medical imaging instruments are often utilized by doctors and other medical professionals to conduct non-invasive examinations. That is, medical imaging instruments, including X-ray, magnetic resonance (MR), computed tomography (CT), ultrasound, and various combinations of these instruments/techniques are utilized to provide images of internal patient structure for diagnostic purposes as well as for interventional procedures. Such medical imaging instruments allow examination of internal tissue that is not readily examined during normal visual or tactile examination. Applications include imaging in the areas of urology and brachytherapy. 
     Medical imaging devices typically allow for generating 3-D images of internal structures of interest. Such 3-D imaging may improve the accuracy and/or reliability of medical diagnosis. For instance, a medical imaging device may be utilized to generate a 3-D model or map of the prostate such that one or more biopsies may be taken from a desired location of the prostate. For purposes of prostrate imaging, image acquisition and guidance may be provided by a transrectal ultrasound-imaging device (TRUS). In such an application, the ultrasound-imaging device may be inserted into the rectum of a patient to generate an image. Such images may be utilized to take one or more biopsies from a prostate location of interest and/or implant radioactive seeds at one or more desired locations in a brachytherapy procedure. 
     In order to generate 3-D images, many medical imaging devices obtain a plurality of images (e.g., two dimensional images) and register these images together to form a 3-D image. Accordingly, movement of a medical imaging device between the acquisition of individual images makes it more difficult to properly align (e.g., register) the different images for purposes of generating accurate 3-D images. 
     Traditionally, having a medical practitioner manipulate the medical imaging instrument by hand has controlled medical instrument positioning for medical image acquisition and/or treatment, including that of ultrasound probes. That is, the medical practitioner manually guides the instrument. Such manual manipulation is suitable for many medical procedures. However, in instances where it is desirable to obtain multiple images for 3-D image generation, manual manipulation of the device may result in movement between images. Further, for biopsy and other treatment procedures it is desirable that the relative location between an imaging instrument and a tissue area of interest be known. That is, it is important that the device directs an imaging field to a particular tissue location and remain stationary to allow for guiding a biopsy/treatment device to a tissue location within the imaging field. Relative movement between the imaging device and the tissue area of interest during imaging and/or biopsy/treatment may impede the successful performance of these procedures. 
     Accordingly, a number of holding and manipulating/positioning assemblies have been proposed wherein a holder interfaces with an imaging device such as an ultrasound probe. Such a holder is then interconnected to one or more mechanical armatures and/or actuators such that the probe may be mechanically positioned and/or rotated. However, original equipment manufactures (OEMs) of ultrasound probes do not have a standardized design. As will be appreciated, ultrasound probes generated by different manufactures come in different lengths and widths. This is true for both the insertion portion end of a probe as well as a handle portion of the probe. This has resulted in the need for specialized holders and/or specialized positioning assemblies for differently configured ultrasound probes. Accordingly, prior positioning assemblies have required that a medical facility utilize a particular probe with a particular positioning assembly. Further, such positioning assemblies have typically been complicated and mechanically cumbersome. 
     SUMMARY OF THE INVENTION 
     Provided herein are devices and methods for the use of such devices for mounting variously configured medical imaging probes for imaging applications. Further, systems and methods are provided for acquiring medical images. In one aspect, a device allows for interfacing/holding most conventional ultrasound probes such that the probes may be attached to a positioning device using a common interface. As ultrasound probes come in various sizes and lengths, the device may adjust to different lengths, widths and shapes of different probes. Hence, the device may work in a substantially universal manner while securely holding probes with little wobble or other problems. The device may also be lightweight and compact to allow it to be used efficiently. The device may also allow use of a biopsy needle and/or a histological gun while a probe is held within the device. 
     In another aspect, the device may be utilized with a manual or automated (e.g., robotic) positioning/rotation device. The positioning/rotation device allows for axial misalignment correction for non-concentric probes to facilitate rotation around the axis of the probe tip. In a further aspect, the positioning/rotation device includes an assembly to allow accurate sampling even during manual rotation by a user. 
     Accordingly, provided herein is an apparatus that allows for interfacing with a plurality of differently configured ultrasound probes. The device includes a clamp body for receiving a portion of the ultrasound probe where the clamp body includes a first body member and a second body member that is moveably attached to the first body member. In this regard, the first and second body members are adapted to move between an open position and a closed position. At least one bias force member is disposed on the surface of one of the first and second body members. A mounting element is also associated with the surface of the clamp body. Such a mounting element allows for mounting the clamp body and, hence, a supported ultrasound probe to a positioning device. 
     Generally, the inclusion of a bias force member on a surface between the first and second body members allows the bias force member to deflect and thereby accommodate differently sized probes. The bias force member also typically applies a force to an ultrasound probe disposed in the clamp when the first and second body members are in a closed position. That is, in addition to accommodating differently sized ultrasound probes, the bias force member also securely hold the probe within the clamp. This may reduce or substantially eliminate relative movement/wobble between the supported ultrasound probe and the clamp body. In a further arrangement, two or more bias force members may be disposed on the inside surfaces of the first and/or second body members. Utilization of separate bias force members may allow for more conformal engagement with a supported ultrasound probe. 
     As utilized herein, the term bias force member includes, without limitation, resilient or elastic members (e.g., elastomeric blocks) disposed on the surfaces of the body members. Such bias force members may compress when the body members are closed relative to an ultrasound probe. In addition, such bias force members also include spring-type members (e.g., coiled springs and/or leaf springs). In any arrangement, a contact surface of the bias force members may be shaped to provide improved contact with an ultrasound probe disposed within the clamp. For instance, the bias force members may have a spherical or otherwise rounded contact surface that allows for improved contact between a probe and the bias force member. Further, a surface of the bias force member may include a gasket or other compressible material that allows for improved contact therebetween. 
     As the bias force member typically applies a force between the first and second body members when disposed about a portion of an ultrasound probe, a latch may be required to maintain the first and second members in a closed position. Any appropriate latch may be utilized. In one arrangement, the latch includes a male pin on one of the first and second body members that may be disposed within a female recess on the other of the first and second body members. In a further arrangement, the first and second body members may move axially relative to one another to allow the pin to be engaged within the recess. Further, such a pin may include a spring-loaded retention ball that is adapted to mate with an indention associated with the female recess. Such a spring-loaded retention ball may reduce or prevent unintended opening of the first and second body members. 
     The first and second body members may be concave members (e.g., half cylindrical members). In such an arrangement, the first and second body members may at least partially define a bore that is sized to receive an ultrasound probe. In such an arrangement, the bias force member(s) may be extend into the bore defined by the first and second body members. In any arrangement, the first and second body members may be pivotally connected. For instance, the first and second body members may be connected utilizing one or more hinge pins. 
     The mounting element associated with the surface of the clamp may be any element that allows the clamp to be interconnected to a desired positioning device. For instance, one or more apertures may be formed in a surface of one or both body members that allow the clamp to be physically connected (e.g., bolted) to a positioning device. Alternatively, the mounting element may be connectable to, for example, an end portion of the clamp body in order to mount the clamp body and/or a supported ultrasound probe to a positioning device. 
     According to another aspect, the device for supporting and rotating an ultrasound probe about a desired axis is provided. The device includes a disk having a first surface that is adapted to be rotatively mounted to a positioning device. A probe holding device is also provided for receiving a portion of an ultrasound probe. A connecting element is utilized to connect the probe holding device to a second surface of the disk. This connecting device may be adjustable to permit the selective positioning of a central axis of a receiving bore of the holding device relative to a rotational axis of the disk. It will be appreciated that often, a handle portion of an ultrasound probe, which may be disposed within the receiving bore, may be offset from an insertion portion or acquisition tip of the ultrasound probe. In this regard, it is desirable that the tip/acquisition portion of the probe rotate about a common axis with the disk. That is, during image acquisition, it is desirable that the acquisition tip of the probe rotate about a fixed axis to reduce registration error. 
     In a further arrangement, an outer periphery of the disk includes a plurality of notches. The device may further include a spring-loaded pawl for engaging the notches. In this regard, a user may, for example, manually turn the disk until the pawl engages a notch on the periphery of the disk. Images may then be acquired. The user may then turn the disk until the pawl engages the next notch. In this regard, the notches may be disposed at an even spacing about the periphery of the disk. 
     According to another aspect, a method for interfacing an ultrasound probe is provided. The method includes disposing a handle portion of an ultrasound probe between first and second body members of a clamp device while the body members are in at least partially open position. Once so disposed, the first and second body members may be moved to a closed position. In conjunction with moving the body members to the closed position, a bias force member may be compressed between the ultrasound probe and at least one of the first and second body members. Accordingly, the first and second body members may be latched together to secure the probe therebetween. 
     The method may further include attaching the clamp device to a positioning device. Such a positioning device may be operative to rotate the probe around at least one fixed axis. In this regard, the method may further include aligning and acquisition portion of the probe with a rotational axis of the positioning device. Such alignment may require offsetting the handle portion from the rotational axis of the positioning device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cross-sectional view of a trans-rectal ultrasound imaging system as applied to perform prostate imaging. 
         FIG. 2   a  illustrates two-dimensional images generated by the TRUS of  FIG. 1 . 
         FIG. 2   b  illustrates a 3-D volume image generated from the two dimensional images of  FIG. 2   a.    
         FIG. 3  illustrates an exemplary ultrasound probe. 
         FIGS. 4A and 4B  illustrate top and bottom perspective views, respectively, of a probe holding device. 
         FIGS. 5A  an  5 B illustrate end views of a probe holding device in open and closed configurations, respectively. 
         FIG. 5C  illustrates an end view of the probe holding device with a compressible gasket. 
         FIG. 5D  illustrates an end view of the probe holding device incorporating a lock release mechanism. 
         FIGS. 6A  an  6 B illustrate end an ultrasound probe disposed in a probe holding device in open and closed configurations, respectively. 
         FIGS. 7A and 7B  illustrate axial movement between upper and lower body members of the device. 
         FIG. 8  illustrates a rear end view of a probe disposed within a probe holding device. 
         FIG. 9  illustrates one embodiment of a positioning device. 
         FIG. 10  illustrates another embodiment of a positioning device. 
         FIG. 11  illustrate an attachment element for attaching a probe holding device to the positioning device of  FIG. 10 . 
         FIG. 12  illustrates a notched disk that allows the positioning device of  FIG. 10  to be manually rotated while providing constant angular rotation for imaging purposes. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the accompanying drawings, which assist in illustrating the various pertinent features of the present disclosure. Although the present disclosure is described primarily in conjunction with transrectal ultrasound imaging for prostate imaging, it should be expressly understood that aspects of the present invention may be applicable to other medical imaging applications. In this regard, the following description is presented for purposes of illustration and description. 
     Disclosed herein are systems and methods that facilitate obtaining medical images and/or performing medical procedures. More specifically, a medical imaging device holder (i.e., holding device or cradle) is provided that is adapted to securely support multiple differently configured ultrasound probes. Further, a simplified rotational mechanism is provided. 
     The probe cradle may be interfaced with the rotational mechanism such that a supported probe may be rotated about a fixed axis. In this regard, multiple images may be obtained from the supported probe in different angular positions for 3-D image generation. As the probe is securely supported by the holding device, there may be little or no probe movement, other than about the fixed axis of rotation, between successive images. Accordingly, successive images may more easily be registered together. In other instances, the holding device may be utilized to securely position a probe relative to a tissue area of interest while a medical instrument is guided to the area of interest. 
       FIG. 1  illustrates a transrectal ultrasound probe being utilized to obtain a plurality of two-dimensional ultrasound images of the prostate  12 . As shown, the probe  10  may be operative to automatically scan an area of interest. In such an arrangement, a user may rotate the acquisition end  14  of the ultrasound probe  10  over an area of interest. Accordingly, the probe  10  may acquire plurality of individual images while being rotated over the area of interest. See  FIGS. 2A-B . Each of these individual images may be represented as a two-dimensional image. See  FIG. 2A . Initially, such images may be in a polar coordinate system. In such an instance, it may be beneficial for processing to translate these images into a rectangular coordinate system. In any case, the two-dimensional images may be combined to generate a 3-D image. See  FIG. 2B . 
     As shown in  FIG. 1 , the ultrasound probe  10  is a side-fire probe that generates ultrasound waves out of the side surface. However, it will be appreciated that end-fire scan probe may be utilized as well. In any arrangement, the probe  10  may also include a biopsy gun (not shown) that may be attached to the probe. Such a biopsy gun may include a spring driven needle that is operative to obtain a core from desired area within the prostate. In this regard, it may be desirable to generate an image of the prostate  12  while the probe  10  remains positioned relative to the prostate. If there is little or no movement between acquisition of the images and generation of the 3D image, the biopsy gun may be positioned to obtain a biopsy (or perform other procedures) of an area of interest within the prostate  12 . However, manual manipulation of the probe  10  often results in relative movement between the probe and the prostate  12  between subsequent images and/or as a biopsy device is guided toward an area of interest. 
     Accordingly, for imaging is desirable that relative movement (e.g., wobble) between the probe  10  and the prostrate  12  be minimized (i.e., other than rotational movement of the probe about a fixed axis for image acquisition). Further, it is often desirable that the probe remains fixed relative to the prostrate  12  during biopsy or other treatment procedures such that desired tissue locations may be accurately targeted. To achieve such fixed positioning of the probe, it is often desirable to interface the probe  10  with a positioning device that maintains the probe  10  in a fixed relative position to the prostate. In order to utilize such a probe  10  with such a positioning device, it is necessary to secure the probe  10  to the device. That is, an interface between the probe and positioning device is required. 
     Complicating the interfacing of an ultrasound probe with a positioning device is the fact that probes made by different probe manufacturers have different dimensions. For instance,  FIG. 3  illustrates an exemplary TRUS probe  10 . As shown, the probe includes an insertion end  14  having a first length L 1  (i.e., insertion length) and a first diameter D 1  (i.e., insertion diameter). The probe  10  also includes a handle  16  having a second length L 2  (i.e., a holding length) and a second diameter D 2 . Further, the probe may have a transition  18  between the insertion end  14  and handle  16 . In the present embodiment, the overall length of the probe  10  is defined by the combined lengths of these components,  14 ,  16  and  18 . 
     However, the dimensions (e.g., lengths and/or diameters) of any or all of these components  14 ,  16  and  18  may vary between probes of different manufactures. Further, these components may be tapered and/or set at an angle to one another. Therefore, to interface different probes to a common positioning device requires either individual probe interfaces (i.e., probe holders) for individual probes, or, a probe holder that is operative to securely hold differently configured probes. Accordingly, provided herein is a universal probe holding device that may be securely connected to a positioning device, where the holding device can securely hold differently configured probes. 
     While different probes may have different dimensions, it is recognized that probes produced for a common purpose (e.g., TRUS probes) are generally similar in size and shape. Accordingly, a holding device may need to accommodate relatively small differences in, for example, handle diameter and/or overall length to permit the device to securely support probes of different manufacturers. 
       FIGS. 4A and 4B  illustrates top and bottom perspective views of a holding device  20  that may be utilized to hold differently configured probes. As shown, the device  10  generally defines a clamp that is designed to open and close about a handle portion of an ultrasound probe. In this regard, the device  20  includes an upper body member  22  and a lower body member  24  that are connected using a hinge. In this regard, the upper body member  22  and lower body member  24  are operative to move relative to one another (e.g., pivot) about a hinge axis, that in the current embodiment is defined by a hinge pin  26 . More specifically, the lower body member  24  includes first and second clevises  30 ,  32  and the upper body member  22  includes a single clevis  28  that is disposed between the first and second clevises  30 ,  32  of the lower body member  24 . As shown, the clevises  28 ,  30 , 32  receive the hinge pin  26  through a plurality of axially aligned apertures in the clevises. 
     The upper and lower body members  22 ,  24  are generally defined as concave members where a recessed surface of each body member  22 ,  24  is generally aligned (e.g., parallel) with the axis defined by the hinge pin  26 . In the present embodiment, the upper and lower body members and  22 ,  24  are generally C-shaped when viewed from an end. See  FIGS. 5A and 5B . In this regard, the upper and lower body members  22 ,  24  may define a bore therebetween when in a closed position. This bore is adapted to receive an ultrasound probe. In this regard, a body/handle  16  of an ultrasound probe  10  may be disposed between the upper and lower body members  22 ,  24  of the device  20  while those members are an open position. See  FIG. 6A . Once an ultrasound probe  10  is disposed between the upper and lower body members  22 ,  24  of the holding device  20 , those members may be moved to a closed position relative to one another. See  FIG. 6B . In the closed position, the probe  10  is secured within the bore that is defined by the first and second body members  22 ,  24 . 
     In order to accommodate differently sized probes, and it is necessary that the inside surface of the holding device  20  at least partially conform to probes having different dimensions. In this regard, the device  20  may be utilized with a variety of differently configured ultrasound probes. Referring again to  FIGS. 4A and 4B , it will be noted that the inside surface of at least one of the body members  22 ,  24  of the device  20  includes a resilient member adapted to conform to the surface of the probe  10  when the first and second body members  22 ,  24  are closed. 
     In this particular embodiment, the resilient member is formed of a bias force member that is adapted to engage a surface of the probe disposed within the bore of the device  20  and apply a force to the probe  10  which prevents relative movement between the probe  10  and the holding device  20 . As shown, the present embodiment utilizes first and second bias force members, which are represented as spring-loaded pressure plates  40 a,  40 b (referred to as pressure plates  40  unless specifically identified). The pressure plates  40  are spring loaded such that when an ultrasound probe is disposed within the device and the device is closed (See  FIG. 8 ), the pressure plates  40  are deflected towards the bottom of the lower body member  24  of the device  20  and exert a force between the probe  10  and the device  20 . 
     As shown, the pressure plates  40  in this particular embodiment, extend through a bottom surface of the lower member  24  when compressed. See  FIGS. 5A-D . However, it will be appreciated that other embodiments may be provided where the bias force members do not extend through the bottom member. The pressure plates  40  include an upper contact surface  42  that is adapted to engage a probe disposed within the bore of the device  10 . This upper contact surface  42  may be rounded and/or partially spherical to provide better contact with the probe. Further, the contact surface  42  may be covered by a resilient material (e.g., a gasket, rubber, elastomeric material or other compressible material) to improve the contact between the bias force member  40  and a probe  10 . This compressible material may have any shape that allows for conformance with a probe  10  dispose within the holding device  20 . For instance, as shown in  FIG. 5C , the gasket may be U-shaped to conform with an outside surface of the probe  10 . Of note, other inside surfaces of the upper and lower body members  22 ,  24  may also include a resilient/compressible material for purposes of providing better contact between the device  20  and a probe  10 . 
     A spring  46  is disposed around outside surface of a body portion  44  of the pressure plate  40 . This spring  46  is disposed between an upper lip on the pressure plate  40  and the bottom inside surface of the lower body member  24 . Compression of this spring allows the body portion  44  of the pressure plate  40  to move through the lower body member  24 . It should be noted that while first and second bias force members  40 a,  40 b are utilized in the current embodiment, more or fewer bias force members may be utilized. Further, such bias force members may take different forms. For instance, a leaf spring may extend between the first and second ends of one or both of them members to provide a conformal fit with a probe disposed within the device  20 . 
     In any embodiment, the bias force members may be deflected when an ultrasound probe is disposed within the device  20 . That is, the bias force members may deflect to accommodate a probe. However, the bias force members will resist such deflection and thereby apply a force between the probe and the device  20  when the upper and lower body members  22 ,  24  are closed. Such deflection and applied force allows differently sized probes to be secured within the device  20 . Further, such applied force allows for holding a probe  10  with little or no relative movement between the device  20  and the probe. That is, such an arrangement allows for reducing wobble between the probe  10  and the holding device  20 . 
     As noted above, the top and bottom body members  22 ,  24  are operative to move relative to one another in order to accommodate an ultrasound probe therebetween. Further, one or both body members  22 ,  24  may include bias force members, e.g., pressure plates, that apply a force between a received probe and the inside surfaces of the device  20 . Accordingly, it is necessary to provide a lock mechanism to maintain the upper and lower body members  22 ,  24  in a closed position when a probe  10  is disposed within the device  20 . 
     The present embodiment of the device utilizes a slide lock arrangement. As shown in  FIGS. 4A , the clevis  28  of the upper body member  22  is narrower than the space between the clevises  30 ,  32  of the body member  24 . This allows the upper body member  22  to move axially along the hinge pin  26  between the clevises  30 ,  32  of the lower body member  24 . That is, the upper and lower body members of the device  20  are permitted to move to axially relative to one another. In this regard, a male connecting pin  50  on one of the body members  22 ,  24  may be selectively received within a mating female recess  52  on the other body member  22 ,  24 . In the present embodiment, an L-shaped connecting pin  50  is attached to the free lateral edge of the upper body member  22 . The corresponding edge of the lower body member  24  includes a recess  52  that opens to an L-shaped cavity. The connecting pin  50  may be disposed within the recess  52  and the upper body member  22  may be advanced axially relative to the lower body member. See  FIGS. 7A and 7B . In such an arrangement, the L-shaped pin  50  may be disposed beneath a lip of the aperture  52  by sliding the upper body member  22  relative to the lower body member  24 . 
     The connecting pin  50  includes a spring loaded retention ball  54  on its front face. See  FIGS. 4A and 5D . When the upper body member  22  of the device  20  is closed relative to the lower body member and the connecting pin  50  is disposed within the recess/aperture  52 , the retention ball  54  engages an indentation  56  or aperture within the cavity that receives the connecting pin  50 . This allows for locking the upper and lower members  22 ,  24  in the position shown in  FIG. 7B . That is, the spring loaded retention ball  54  provides a resistance to being retracted from the indentation  56  and thereby prevents unintentional opening of the device. In order to open the device  20 , the upper body member  22  is retracted with either a force that is sufficient to overcome the spring loading of the retention ball, which then disengages from the indentation  56  and allows the connecting pin  50  to be withdrawn from the cavity. Alternatively, the lower body member  24  may have a release mechanism  58 . See  FIG. 5D . By depressing the release mechanism  58 , the retention ball  54  may be disengaged from the indention  56  and thereby facilitate the retraction of the connecting pin  50  from the recess  52 . However, it will be appreciated that other locking mechanisms may be utilized to maintain the upper and lower members  22 ,  24  in a closed position and such mechanisms are within the scope of the present invention. 
       FIG. 4B  illustrates a bottom perspective view of the device  10 . As shown, on the outside surface of the lower body member  24 , there is a plurality of mounting holes  60  that forms one embodiment of a mounting element for the device  20 . These mounting holes  60  may be utilized to mount the device to a positioning device such as, for example, a robotic positioning device. However, it should be noted that other arrangements for mounting the device  20  to a positioning device are possible and considered within the scope of the invention. 
     Of note, a top edge  23  of the upper member  24  may be shaped in a manner that permits a biopsy needle or other treatment element to access the insertion end  14  of the probe  10 . As illustrated by  FIGS. 5A ,  5 B and  8 , the top edge  23  of the upper member is flattened to permit access past the holding device  20  to the insertion end of the probe  10 . This flattened section  23  may also be used to mount an emergency switch for immediate release of the TRUS probe from the rectum of the patient and to immediately stop any automatic motion.  FIG. 9  illustrates one embodiment of a robotic actuator (e.g., positioning device) to which the holding device  20  may be connected. However, it will be appreciated that any robotic actuator may be utilized, and the illustrated robotic actuator is provided by way of illustration and not by limitation. What is important is that the holding device  20  may be affixed to a positioning device and that the holding device  20  accommodates ultrasound probes having different physical configurations. In this regard, the holding device may receive and securely hold ultrasound probes from various different manufacturers such that differently configured probes may be utilized with a single positioning device. Further, the probe held by the device  20  is secured by the resilient and/or bias force members disposed within the clamp, which prevents wobble (e.g., relative movement between the holding device  20  and probe  10 ). 
     During image acquisition, it is typical to insert the insertion end of an ultrasound probe relative to a tissue area of interest (e.g., the prostrate). Once so positioned, the probe may be rotated around the axis of its tip (e.g., for an end-fire probe) while a plurality of 2-D images are obtained for use in generating a 3-D image. Preferably, the images are acquired at equal angular offsets in order to provide an improved 3-D image. 
     In this regard, it is desirable that the probe tip and typically the insertion end of the probe rotate around a fixed axis. However, as illustrated by  FIGS. 3 ,  6 A and  6 B, it is noted that in many instances the axis of the insertion end  14  of the probe  10  is offset from the axis of the handle  16  of the probe  10 . Further, when the probe  10  is disposed within the holding device  20 , the axis of the insertion end  14  of the probe is offset from the central axis of the holding device  20 . In order to effectively rotate the probe  10  around the insertion/tip axis, it may be necessary to rotate the holding device  20  and, hence, the handle  16  of the probe  10  about an offset axis. That is, it may be necessary to correct for axial misalignment of the probe  10 . 
     Accordingly,  FIG. 10  provides an illustration of a device that allows correcting the misalignment of the axes of the probe  10  such that the rotation takes place with respect to the insertion end/tip of the probe  10 . As shown, the assembly  100  allows for correcting the misalignment of the axis of the insertion end of the probe (axis  1 ) and the axis of the handle/holding device (axis  3 ). Generally, the assembly  100  includes a rotating disk  70 , which may be rotatively coupled to a positioning device and/or robotic arm (e.g., of  FIG. 9 ). The axis of rotation of the insertion end of the probe  10  is aligned with the axis of rotation of the rotating disk  70  (i.e, axis  1 ). 
     To permit alignment of the insertion end  14  of the probe  10  with the rotational axis of the disk  70 , the holding device  20  must be connected to the disk  70  at a distance from the axis of rotation (axis  1 ) to account for the offset between the insertion end  14  of the probe and the probe handle  16  and/or central axis of the holding device  20 . As shown in  FIGS. 10 and 11 , the holding device  20  is connected to an axis alignment tool  74 . As shown, the axis alignment tool  74  interconnects to the probe holding device  20 . The axis alignment tool forms a second embodiment of a mounting element for the holding device  20 . The axis alignment tool  74  is adapted to be mounted to the parallel axis offset tool  80 . 
     The parallel axis offset tool  80  is interconnectable to the disk  70  at a position (axis  2 ) that is offset from the axis of rotation (axis  1 ) of the disk  70 . By adjusting the angular position of the parallel axis offset tool  80  relative to its connection point (i.e., axis  2 ) with the disk  70 , the axis of the insertion end  14  of the probe may be aligned with the rotational axis of the disk  70 . That is, the parallel axis offset tool  80  will be rotated about axis  2  and the axis alignment tool may be displaced such that the insertion end axis is substantially aligned with the axis of rotation (i.e, axis  1 ). 
     As may be appreciated, in most instances of manual image sampling, a user is not able to uniformly control the angular rotation of the probe between successive samples. That is, manual acquisition of ultrasound data suffers from the drawback of irregular sampling rates and such irregularly sampled data may cause bad image quality when reconstructed into a 3-D image. The design of the assembly  100  of  FIG. 10  may also be adapted to allow for uniform sampling during manual rotation of the probe  10 . 
     The assembly shown in  FIG. 12  provides a mechanism for manual rotation of a TRUS probe at regularly spaced acquisition angles. The saw-tooth disk  72 , which may be incorporated into a positioning mechanism (e.g., see  FIGS. 9 and 10 ), has uniformly spaced notches  82  about its periphery. Further the saw-toothed disk  72  may include a combination of discs (e.g., stacked) with different sampling angles. As a user rotates the assembly, a spring-loaded pin or pawl  84  engages the notches. Accordingly, images may be sampled at each notch. This ensures that 2-D images are acquired at uniform sampling angles. It will be appreciated that the saw-toothed wheel may have notches defining various desired sampling rates such as 1°, 2°, 3°, resulting in a flexible, yet uniform manual sampling apparatus. 
     The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in similar or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.