Abstract:
An introducer for use with an ultrasonic imaging system. The introducer comprises a tubular member having a connecting end, a positioning end, and a central lumen, the connecting end including a coupling for attaching the introducer to an ultrasonic imaging system, and the positioning end comprising a plug or other structure that facilitates positioning of the introducer inside a urethra at a fixed anatomical landmark.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to ultrasonic imaging systems and, in particular, to an introducer for use with an ultrasonic imaging system. In a particularly preferred embodiment, the invention relates to an introducer for use with transurethral ultrasonic imaging systems.  
       BACKGROUND OF THE INVENTION  
       [0002]     When performing ultrasonic imaging within a tissue region or body lumen, such as a patient&#39;s urethra, it is important to ensure proper coupling of the energy generated and received by an imaging transducer to the surrounding tissues, and it is also often important to protect the surrounding tissues from abrasion or other harm.  
         [0003]     The present invention is directed to an introducer that functions to enhance energy transfer or acoustic coupling between an imaging transducer that is placed within a body lumen, such as a patient&#39;s urethra, and surrounding tissues. In various embodiments, the present invention also relates to the configuration, storage, and packaging of such an introducer.  
       SUMMARY OF THE INVENTION  
       [0004]     Exemplary embodiments of the present invention that are shown in the drawings are summarized below. These and other embodiments are more fully described in the Detailed Description section. It is to be understood, however, that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.  
         [0005]     In one presently preferred embodiment, an introducer is provided which comprises a tubular member defining a lumen wherein the tubular member comprises an open proximal end that is adapted to connect to an ultrasonic imaging system to allow insertion of an ultrasonic imaging catheter into the lumen. The tubular member further comprises a closed distal end and an imaging section that is transparent to ultrasonic waves. The introducer also may contain an acoustic coupling medium to enhance acoustic coupling between the ultrasonic imaging catheter, the tubular member, and any surrounding tissues. A seal may be used to retain the acoustic coupling medium within the lumen, and in such embodiments, the seal preferably is breachable or may be penetrated by the ultrasonic imaging catheter.  
         [0006]     In the above described embodiment, the seal may be provided, for example, by a cap structure, a releasable tubular seal, or a clamped fold of the tubular member. And, depending upon the intended application, the acoustic coupling medium may comprise water, some other type of liquid, such as saline solution, or a gel.  
         [0007]     In still further embodiments, the introducer may include a distal tip or plug that may be used to position the distal end of the introducer within a particular region of interest, such as adjacent a patient&#39;s bladder sphincter or bladder neck.  
         [0008]     As previously stated, the above-described embodiments and implementations are for illustration purposes only. Numerous other embodiments, implementations, and details of the invention are easily recognized by those of skill in the art from the following descriptions and claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1A  illustrates a sectional view of an introducer, in accordance with an embodiment of the invention.  FIG. 1B  illustrates the introducer shown in  FIG. 1A  connected to an ultrasonic imaging system.  
         [0010]      FIG. 2  is an illustration of an introducer, covered with a sheath, and including a fold-over clamp seal, prior to the introducer&#39;s insertion into a patient&#39;s urethra, in accordance with an embodiment of the invention.  
         [0011]      FIG. 3A  and  FIG. 3B  illustrate an introducer system with a hydrophilic coating, in accordance with an embodiment of the invention.  FIG. 3A  shows the introducer before a catheter has been inserted into the lumen.  FIG. 3B  shows the introducer with the catheter in the process of being inserted.  
         [0012]      FIG. 4  is a sectional schematic anatomical view showing an ultrasonic imaging catheter within an introducer inside a patient&#39;s prostatic urethra, in accordance with an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     For the sake of convenience, several terms used to describe various human anatomical structures and embodiments of the invention are defined below. It should be understood that these are provided merely to aid the understanding of the description, and that the definitions should in no way limit the scope of the invention, which is defined by the appended claims.  
         [0014]     Anterior: Situated at the front or the front surface of an organ.  
         [0015]     Apex of the prostate: The end of the prostate gland located farthest away from the urinary bladder.  
         [0016]     Axial/Longitudinal: Along the centerline of the urethra, regardless of patient position.  
         [0017]     Biopsy: The removal of a small sample or samples of tissue for examination under a microscope or other device.  
         [0018]     Bladder: The hollow organ that stores and discharges urine from the body.  
         [0019]     Bladder neck: The outlet area of the bladder. It is composed of circular muscle fibers (bladder sphincter), and helps control urine flow from the bladder into the urethra.  
         [0020]     Catheter drive mechanism: A motion control system that can provide axial and/or rotational motion to an imaging catheter, or an ultrasonic transducer disposed within an imaging catheter.  
         [0021]     Distal: Remote, farther from any point of reference (the opposite of proximal).  
         [0022]     Genitourinary system: Pertaining to the genital and urinary systems.  
         [0023]     Imaging catheter: A tubular mechanism, containing an ultrasonic transducer for organ-tissue imaging.  
         [0024]     Inferior: Anatomically refers to a lower surface of an organ, or a location situated below a given reference point.  
         [0025]     Intraluminal: Within a lumen, such as a vessel or other tubular passage within the body, an organ of the body, or an area of tissue within the body.  
         [0026]     Introducer: A device that facilitates the insertion of a catheter into the urethra.  
         [0027]     Periluminal: Around a lumen, such as a vessel or other tubular passage within the body, an organ of the body, or an area of tissue within the body.  
         [0028]     Posterior: Situated at the back or the back surface of an organ.  
         [0029]     Prostatic Urethra: The segment of the urethra, which is surrounded by prostatic tissue from the proximal end at the bladder neck to the distal end at the apex of the prostate gland.  
         [0030]     Proximal: Closer to any point of reference.  
         [0031]     Superior: Anatomically refers to an upper surface of an organ, or situated above a given reference point.  
         [0032]     Transducer: A device, which transforms one form of energy to another form of energy (e.g. electrical to acoustical energy, or, conversely, acoustical to electrical energy).  
         [0033]     Transurethral: A procedure performed through the urethra.  
         [0034]     Transverse: Placed crosswise, situated at right angles to the long axis of an organ.  
         [0035]     Various embodiments of the invention are directed to an introducer for use with a transurethral ultrasonic imaging system. Some embodiments include an acoustic coupling medium, and others include a sheath which covers the introducer, protecting it from contamination. A further embodiment includes a sheath and a lubricant to facilitate insertion of the introducer into a patient. Other embodiments include a hydrophilic coating on the introducer to enhance lubricity and elements to facilitate hydrating the hydrophilic coating. Some embodiments have a rigid plug at the tip of the introducer to facilitate proper placement of the ultrasonic transducer prior to imaging. The system elements and various embodiments of the invention are described in detail with reference to the appended drawings.  
         [0036]      FIG. 1A  illustrates a sectional view of an introducer  100  in accordance with an embodiment of the invention. Introducer  100  includes tubular member  102  which provides the primary structure of the introducer  100 . Lumen  104  is the passageway or opening within the tubular member  102 . The proximal end  106  of the introducer  100 /tubular member  102  is open. The distal end  108  of the introducer  100 /tubular member  102  is closed.  
         [0037]     At the proximal end  106  the introducer  100  has a connector  110 . At the distal end  108  there is a distal seal  112  which performs the function of closing the distal end  108  to the passage of fluid. FIG IA illustrates the distal seal as a plug. In another embodiment (not shown) the distal seal is formed from the end of the tubular member  102  without additional material.  
         [0038]     At another point along the length of the tubular member  102  a proximal seal  114  is situated.  FIG. 1A  illustrates the proximal seal  114  as a removable clamp. In another embodiment (see  FIG. 2 ) the proximal seal  114  is created by folding the tubular member  102  over on itself and securing it in that position until it is ready to be used.  
         [0039]     Within the tubular member  102  and between the distal seal  112  and the proximal seal  114  a volume is defined. This volume is filled with an acoustic coupling medium  116 . The purpose of acoustic coupling medium is to allow passage of ultrasonic waves with minimal loss. Air is a very poor coupling medium for ultrasonic imaging. Examples of good ultrasonic coupling media are: pure water, water with certain additives, certain mineral oils, and certain gels.  
         [0040]      FIG. 1B  illustrates the introducer  100  shown in  FIG. 1A  ready for use. The proximal seal  114  has been removed. An ultrasonic imaging catheter  302 , which is part of an ultrasonic imaging system  300 , has been inserted in through the lumen  104  of the introducer  100 . Introducer  100  has been connected to the ultrasonic imaging system using the connector  110 .  
         [0041]     The tip  306  of the ultrasonic imaging catheter  302  contains an ultrasonic transducer  304  whose purpose is to send out ultrasonic waves and detect the reflections of those waves from non-homogeneous regions of the organ being imaged. The ultrasonic imaging system  200  may rotate the ultrasonic transducer  304  to obtain planar or conical image slices. The ultrasonic imaging system  300  may also move the transducer  304  axially to obtain a 3-D image.  
         [0042]     In order for the ultrasonic imaging system  300  to function properly the ultrasonic waves emanating from and returning to the transducer  304  should not be impeded. There is therefore an imaging section  118  of the introducer, corresponding to the axial travel of the transducer  304 , where the tip of the catheter  306  should remain immersed in the coupling medium  116  and the tubular member  102  should be transparent to ultrasonic waves. An example of a structural material that is transparent to ultrasonic waves is polyethylene.  
         [0043]     In accordance with an embodiment of the invention the tubular member  102  has an outside diameter of approximately 4 mm. The outside diameters of other embodiments fall in the range of 2.5 mm to 8 mm. In accordance with an embodiment of the invention the wall thickness of the tubular member  102  is approximately 0.2 mm. The wall thickness of other embodiments fall in the range of 0.1 mm to 0.5 mm  
         [0044]     Turning now to  FIG. 2 , in accordance with an embodiment of the invention an introducer is shown as packaged prior to use. A closed-ended sheath  122  covers a tubular member  102  of the introducer from a distal end  108  to a connector  110  at a proximal end  106 . This sheath  122  helps maintain cleanliness and sterility of the tubular member  102  during handling, as an imaging catheter is being inserted into the introducer, and as the introducer is connected to an ultrasonic imaging system. The sheath  122  is removed prior to the tubular member  102  being inserted into a patient&#39;s urethra.  
         [0045]     In accordance with an embodiment of the invention a proximal seal  114  is created by folding the tubular member  102  over on itself. Those skilled in the art will note that this construction is valid with or without the sheath  122 . A restraint  120  maintains the seal until the restraint  120  is removed by the user in order to insert an imaging catheter into the catheter.  
         [0046]     In accordance with another embodiment of the invention, a cap  124  covers the open proximal end  106  of the introducer. The cap  124  is attached to the connector  1   10 . The cap  124  is removed prior to the insertion of an imaging catheter and prior to the connection of the introducer to an ultrasonic imaging system.  
         [0047]     In accordance with an embodiment of the invention a lubricant  126  occupies the space between the outside of the tubular member  102  and the inside of the sheath  122 . As the sheath  122  is removed a substantial amount of lubricant  126  remains with the tubular member  102 . This lubricant aids in the safe insertion of the tubular member  102  into the patient&#39;s urethra.  
         [0048]     The sheath  122  may be constructed of a flexible, impermeable material such as polyethylene.  
         [0049]      FIG. 3A  and  FIG. 3B , in accordance with an embodiment of the invention, illustrate a hydrophilic introducer system  103 . The hydrophilic introducer system  103  includes a tubular member  102  which has a hydrophilic coating  128  on its outer surface. The purpose of the hydrophilic coating is to reduce friction between the tubular member  102  and the patient&#39;s tissue as the tubular member  102  is inserted into the patient&#39;s urethra. An example of a hydrophilic coating is a hyaluronan-based coating. Hydrophilic coatings should be immersed in water, typically for 30 seconds, before they are ready for use.  
         [0050]     The hydrophilic introducer system  103  also may include a proximal seal  114 , a water-based acoustic coupling medium  116 , a sheath  122 , a distal one-way valve  130 , and a distal opening  132 .  
         [0051]      FIG. 3A  shows the hydrophilic introducer system  103  before a catheter  302  has been fully inserted. The coupling medium  116  is constrained within the tubular member  102  between the proximal seal  114  and the distal one-way valve  130 . During normal handling of the introducer system the coupling medium  116  will remain so constrained and the annular space  134  between the tubular member  102  and the sheath  122  will remain dry.  
         [0052]      FIG. 3B  shows the hydrophilic introducer system  103  with the catheter  302  in the process of being inserted in through the tubular member  102 . The catheter  302  has passed the proximal seal  114  which now seals against the catheter  302  to prevent the coupling medium  116  from leaking out the proximal end  106 . As the catheter  302  displaces the coupling medium  116  within the tubular member  102  the coupling medium  116  is forced past the one-way valve  130 , through the distal opening  132  and into the annular space  134  where it comes in contact with the hydrophilic coating  128 . The arrows in the figure represent movement of the coupling medium  116 .  
         [0053]     In another embodiment of the invention the proximal seal  114  also acts as a one-way valve—allowing air from outside to enter as the catheter  302  is being withdrawn.  
         [0054]     In another embodiment of the invention there is a proximal one-way valve (not shown) in addition to the proximal seal  114 .  
         [0055]     Turning now to  FIG. 4 , in accordance with an embodiment of the invention, a sectional anatomical view showing the ultrasonic imaging catheter  302  within the introducer  100  and inside a patient&#39;s prostatic urethra  400  is illustrated. The ultrasonic imaging catheter  302  is connected to the ultrasonic imaging system  300  for imaging the patient&#39;s prostate gland  404 . In accordance with an embodiment of the invention, the ultrasonic imaging system  300  is a transurethral prostate imaging system. In accordance with another embodiment of the invention, the ultrasonic imaging catheter  302  is connected to a drive mechanism of the ultrasonic imaging system  300  (not shown in  FIG. 4 ). The drive mechanism of the ultrasonic imaging system  300  rotates an ultrasonic transducer  304  inside the ultrasonic imaging catheter  302 . In accordance with another embodiment of the invention the drive mechanism of the ultrasonic imaging system  300  can also move the imaging catheter  302  axially relative to the introducer  100  enabling the ultrasonic imaging system  300  or its adjuncts to construct a three dimensional image of the prostate.  
         [0056]     During a 3-D imaging session it is important to place the ultrasonic transducer  304  in a suitable position before imaging begins due to mechanical travel limitations and patient discomfort considerations. For example, if a complete scan of the prostate  404  is desired, using an ultrasonic imaging system  300  which withdraws the imaging catheter  302  while imaging, then the transducer  304  should initially be positioned (within the urethra) so the initial 2-D image is on the distal side of, yet close to, the prostate  404 , the distal side of the prostate  404  being the side towards the urinary bladder  408 .  
         [0057]     In accordance with an embodiment of the invention the introducer  100  includes a relatively rigid plug  136  at the distal tip. In other embodiments this rigid structure may assume other configurations, such as a thickened or enlarged section of the tubular member  102 . The purpose of the rigid plug  136  is to define the distal tip of the catheter  100  as it is being inserted into the urethra. When the rigid plug  136  reaches the bladder sphincter  406  there will be increased resistance when inserting the introducer  100 . This is a signal for the person inserting the introducer  100  to stop as this point closely approximates the ideal starting point for the ultrasonic transducer  304 . During imaging the introducer  100  remains stationary relative to the patient while axial movement of the imaging catheter  302  occurs relative to the introducer  100 .  
         [0058]     It will be evident to a person ordinarily skilled in the art that one or more of the embodiments mentioned above provide the following advantages during transurethral ultrasonic imaging of the genitourinary system of a patient. The introducer may significantly reduce the incidence of cross-contamination between patients since it isolates the ultrasonic imaging catheter from contact with the patient&#39;s bodily fluids, and since it is disposable due to its relatively low manufacturing cost. The introducer may serve as an anchoring device, maintaining a fixed relationship to the patient as the ultrasonic imaging catheter is moved axially, thus allowing precise control of the movement of the ultrasonic transducer relative to the patient&#39;s organ being imaged. A rigid plug at the tip of the introducer may aid in the proper initial placement of the ultrasonic transducer. The sheath helps maintain cleanliness and sterility of the introducer even after the introducer is installed on the ultrasonic imaging system and up to the point the introducer is inserted into a patient&#39;s urethra. The sheath may contain a lubricant to facilitate insertion of the introducer into a patient&#39;s urethra. The introducer may have a hydrophilic coating to provide lubricity. A sheath and associated valves may enable convenient wetting of the hydrophilic coating.  
         [0059]     While the invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or systems or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.