Abstract:
An echogenic medical device includes a shaft having a proximal portion, a distal portion, first and second opposing longitudinal sides, and a passageway extending therethrough. The distal end includes a beveled opening communicating with the passageway, and extending between a distal tip portion disposed along the first longitudinal side and a heel portion disposed along the second longitudinal side. A first echogenic region extends circumferentially around the shaft at the distal portion. The first echogenic region is structured for providing a signal visible along the circumference of the shaft under ultrasound visualization. A second echogenic region extends along a length of the second longitudinal side and is substantially aligned with the heel portion. The second echogenic region is structured and arranged for providing a generally linear signal visible under ultrasound examination along the second longitudinal side, and substantially not visible along the first longitudinal side.

Description:
RELATED APPLICATION 
       [0001]    The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 61/590,495, filed Jan. 25, 2012, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a medical device constructed for visualization within the body of a patient under medical imaging. More particularly, the invention relates to an echogenic medical device configured such that the location and rotational orientation of the device in the body of a patient may be observed in real time under ultrasound visualization. 
         [0004]    2. Background Information 
         [0005]    The ability to monitor the location and orientation of surgical instrumentation within intraluminal and extraluminal regions of the body of a patient has attained increased importance in recent years. Instruments formed of fluoroscopic and radiopaque materials are widely used to create visible regions within the body. Fluoroscopy is a technique in which an x-ray beam is transmitted through a patient to generate images of the target structure that can be displayed in a monitor. It can also be used to observe the position of instruments during diagnostic procedures. However, the use of x-ray exposes the patient to potentially harmful radiation. Additionally, health care workers must typically transport the patient to a specially-equipped radiology facility to obtain the x-ray, thereby increasing the cost and complexity of the procedure. Further, the images obtained via fluoroscopy may not achieve sufficient clarity to provide the desired level of detail to the medical professional. 
         [0006]    Conventional endoscopy offers visualization of the immediate regions within which the endoscope is positioned by way of a video camera attached at the distal end of the endoscope. However, the video camera provides a field of view limited to only the immediate region. Surgical instrumentation within the immediate region that is obstructed by body features or by other instrumentation cannot be visualized. Similarly, instrumentation outside of the immediate region, such as outside the lumen in which the endoscope has been positioned, cannot be visualized with the endoscopic video camera. 
         [0007]    Ultrasound imaging is another option that has been used to monitor the placement of medical instrumentation. Ultrasound imaging utilizes high frequency sound waves to create an image of living tissue. As ultrasound waves are emitted, the waves are reflected upon encountering a surface change. The reflected waves are captured to create an image, which image is displayed on a monitor in real time. Ultrasound imaging allows for monitoring of the medical devices in extraluminal regions, as well as in intraluminal regions. Such monitoring is readily used in modern medicine to guide a medical device to a target site, while at the same time minimizing the possibility of inadvertent injury to adjacent tissue resulting from a misplaced device. 
         [0008]    Ultrasound visualization has additional favorable characteristics in that it can be performed at the bedside, and it eliminates exposure of the patient to hazardous radiation. Although ultrasound visualization provides benefits not available with other medical techniques, there are some shortcomings associated with this technique. For example, the device to be observed under ultrasound may not be easily visible at certain angles relative to the ultrasound probe. In addition, the ultrasound image may not provide sufficient detail to enable the medical professional to determine with a high degree of confidence the particular orientation of the instrument in the viewing region, such as the degree of rotation of the device in the region. 
         [0009]    It would be desirable to provide an echogenic device that is structured such that specified features of the device can be visualized in real time when the device is positioned within the body of the patient with greater precision than available with prior art devices. 
       SUMMARY 
       [0010]    The present invention addresses the problems of the prior art. In one form thereof, the invention comprises a medical device configured for insertion into the body of a patient and ultrasound-guided movement therein to an interior target site. A shaft has a proximal portion and a distal portion, wherein the distal portion extends to a distal end. A first echogenic region at the distal portion is structured for providing a signal visible under ultrasound visualization. A second echogenic region proximal of the first echogenic region is structured and arranged for providing a signal visible under ultrasound visualization. The signal at the second echogenic region is visually distinguishable from the signal at the first echogenic region. 
         [0011]    In another form thereof, a medical device configured for insertion into the body of a patient and ultrasound-guided movement therein to a target site is disclosed. A shaft has a proximal portion and a distal portion, wherein the distal portion extends to a distal end. An echogenic region at the distal portion comprises a plurality of geometric configurations disposed along the distal portion. At least some of the geometric configurations extend into a matrix of the shaft and define at least two wall angles 1, 2 . Each of the wall angles is configured and positioned to enhance an echogenicity of the geometric configuration under ultrasound visualization. 
         [0012]    In still another form thereof, an echogenic needle is disclosed. The echogenic needle includes a shaft having a proximal portion, a distal portion extending to a distal end, first and second generally opposing longitudinal sides extending along the proximal and distal portions, and a passageway extending therethrough. The distal end defines a beveled opening communicating with the passageway. The beveled opening extends between a distal tip portion disposed along the first longitudinal side and a heel portion disposed along the second longitudinal side. A first echogenic region extending circumferentially around the shaft at the distal portion is structured for providing a signal visible along substantially the entire circumference of the shaft under ultrasound visualization. A second echogenic region extending along a length of the second longitudinal side and substantially aligned with the heel portion is structured and arranged for providing a generally linear signal visible under ultrasound examination along the second longitudinal side, and substantially not visible along the first longitudinal side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a side view of the distal portion of a prior art echogenic needle; 
           [0014]      FIG. 2  is a side view of the distal portion of the prior art echogenic needle, rotated 90 degrees from the orientation as shown in  FIG. 1 ; 
           [0015]      FIG. 3  is a side view of the distal portion of an echogenic needle according to an embodiment of the present invention; 
           [0016]      FIG. 4  is a side view of the distal portion of the echogenic needle of  FIG. 3 , rotated 90 degrees from the orientation as shown in  FIG. 3 ; 
           [0017]      FIG. 5  is a side view of another example of an echogenic needle, wherein the echogenic region includes multiple echogenic shapes; 
           [0018]      FIG. 6  is a side view of the distal portion of the echogenic needle of  FIG. 5 , rotated 90 degrees from the orientation as shown in  FIG. 5 ; 
           [0019]      FIG. 7  is a side view of still another example of an echogenic the distal portion of an echogenic needle similar to that of  FIG. 5 , wherein the echogenic shapes are provided in a random rotational pattern along the side of the echogenic needle; 
           [0020]      FIG. 8  is a side view of the distal portion of the echogenic needle of  FIG. 7 , rotated 90 degrees from the orientation as shown in  FIG. 7 ; 
           [0021]      FIG. 9  is a side view of the distal portion of an echogenic needle according to yet another alternative embodiment, including multiple bands of echogenic elements, wherein each band is formed of elements having a configuration that differs from the elements of another band; 
           [0022]      FIG. 10  is a side view of the distal portion of another embodiment of an echogenic needle according to the present invention, illustrating shaped dimples extending inwardly into the surface of the needle; 
           [0023]      FIG. 11  is an enlarged view of one of the shaped elements of the needle of  FIG. 10 ; 
           [0024]      FIG. 12  is a tangential sectional view of the needle and shaped element taken along A-A of  FIG. 11  and illustrating angle 1 ; 
           [0025]      FIG. 13  is an axial sectional view of the needle and shaped element taken along B-B of  FIG. 11  and showing angle 2 ; 
           [0026]      FIG. 14  is a side view of a catheter having an echogenic ribbon applied along the top outer surface of the catheter; and 
           [0027]      FIG. 15  is a top view of the catheter of  FIG. 14 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    For purposes of promoting an understanding of the present invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0029]    In the following discussion, the terms “proximal” and “distal” will be used to describe the opposing axial ends of the device, as well as the axial ends of various component features of the device. The term “proximal” is used in its conventional sense to refer to the end of the device (or component thereof) that is closest to the operator during use of the device. The term “distal” is used in its conventional sense to refer to the end of the device (or component thereof) that is initially inserted into the patient, or that is closest to the patient during use. 
         [0030]    As used herein, the term “echogenic” is defined as having enhanced echogenicity. Specifically, it is used to refer to a structure, or a portion of a structure, constructed or treated in a manner to provide greater reflectivity of ultrasonic waves than the structure, or structure portion, would exhibit in the absence of such construction or treatment, and/or that is capable of providing an echogenic profile relative to surrounding tissues during use of the structure in the body of a patient. 
         [0031]    It is known in the art that materials used for medical devices, such as a needle, sheath, catheter, cannula, stylet, etc., will reflect some ultrasonic waves. However, the term “echogenic,” as used herein includes constructing or treating the device by creating, e.g., a textured, patterned, indented, angled or otherwise irregular surface including, for example, one or more dimples, divots, knurls, ridges, nubs, and the like (hereafter collectively referred to as “dimples”), each of which is known in the art to enhance echogenicity as compared to a more smooth or untreated surface for a similarly-sized/shaped object, and/or applying a material to the device capable of enhancing the echogenicity of the device when compared to a device not having the material applied thereto, and/or forming the device, or a discrete portion of the device, of a matrix suitable for enhancing echogenicity when compared to an otherwise similar device or device portion not formed of the echogenicity-enhancing matrix. 
         [0032]      FIG. 1  illustrates a side view of the distal portion of a prior art echogenic medical device, in this case, an echogenic needle  10 .  FIG. 2  is a side view of the distal portion of the needle  10 , rotated 90 degrees from the orientation as shown in  FIG. 1 . Needle  10  has a generally elongated body  12  of an appropriate length that extends to a distal end  13 . Distal end  13  terminates at distal tip  14 . Distal tip  14  is structured for penetrating, e.g., the outer skin of the patient, an occlusion, a body wall, an organ, or other bodily structure positioned along a path to a target site. Needle  10  has a beveled opening  16  that leads to a lumen (not shown) extending through the elongated body  12 . As described herein, a beveled opening refers to an opening that is angled, or inclined, with regard to the main axis of the medical device at an angle other than a right angle. Needle  10  may also include an outer sheath  11  or like structure that extends to, or beyond, the proximal end (not shown) of the needle. 
         [0033]    Prior art needle  10  includes an echogenic structure at its distal end. In this example, the echogenic structure comprises a pattern of dimpling  20  extending circumferentially around the distal end of the needle. It is known in the art to provide certain echogenic patterns along a medical device, such as a needle, and the pattern shown in  FIG. 1  is one example of a known pattern. This and similar patterns are provided on needles commercially available from Cook Medical Technologies, LLC, Bloomington, Ind., and referred to as ECHOTIP® needles. Other echogenic patterns, as well as devices to which such patterns have been applied, are disclosed in U.S. Pat. No. 4,869,259, and U.S. Pat. Publ. Nos. 2006/0247530, 2008/0097213, and 2011/0046619. All patents and patent publication documents referred to herein are incorporated by reference in their entireties. 
         [0034]    The known echogenic patterns, such as the pattern illustrated in the prior art needle of  FIG. 1 , have generally proven effective in enabling the ultrasound technician to locate, and track, the axial position of the distal tip of the needle within the body of the patient. However, this echogenic pattern is generally visible on the monitor as a brightened portion of the ultrasound image. The image is not provided in sufficient detail to enable the medical professional to determine the alignment, or rotational orientation, of the beveled opening of the needle. 
         [0035]    It would be advantageous to have the capability of locating features of a medical device within the body of the patient with greater precision than available with prior art devices, such as the needle shown in  FIG. 1 . For example, it would be beneficial if the medical professional could determine the rotational orientation of the bevel of the needle. In this way, the professional could readily distinguish the position of the tip  14  of the bevel from the bevel heel  18 . Armed with this knowledge, the professional could thereby ensure that the needle is oriented for insertion such that the tip enters the target structure first. 
         [0036]    Without the ability to distinguish the rotational orientation of the needle as described, the medical professional may attempt to lead into the target site with the bevel heel side of the needle, instead of with the tip side. In this event, and particularly in those instances when entry is attempted at an angle to the vessel or other target structure, the stick may be unsuccessful, as the needle may deflect off the vessel or structure. When this occurs, the professional must rotate the needle in an attempt to lead with the needle tip  14 . However, due to the lack of visibility on ultrasound, and in particular, an inability to distinguish the bevel heel from the distal tip on the ultrasound monitor, such rotation includes a certain element of trial and error. If sufficient rotation is not achieved, a second, or even a third attempt could also be unsuccessful. Any unsuccessful attempts add unnecessary time and effort to the procedure. Additionally, such unsuccessful attempts at entry may cause additional trauma to the patient. Even when entry is made, the professional can still not generally be certain of the exact orientation of the opening. 
         [0037]      FIG. 3  illustrates a side view of the distal portion of an echogenic medical device according to an embodiment of the present invention.  FIG. 4  is another side view of the distal portion of the device rotated 90 degrees from the orientation shown in  FIG. 3 . In the example of  FIGS. 3 and 4 , the echogenic medical device comprises an echogenic needle  100 . As illustrated, needle  100  has some similarities to prior art needle  10  shown in  FIGS. 1 and 2 . For example, needle  100  has a generally elongated body  102  of an appropriate length, and extends to a beveled opening  106  at distal end  103 . Beveled opening  106  is bordered at the distal end by distal tip  104 , and at the proximal end by heel  108 . As with the prior art needle, distal tip  104  is structured for penetrating, e.g., the outer skin of the patient, an occlusion, a body wall, an organ, or other bodily structure positioned along a path to the target site. Needle  100  may also include an outer sheath  101 , or like structure, that extends to, or beyond, the proximal end (not shown) of the needle, as well known in the art. 
         [0038]    In this example, needle  100  includes a circumferential pattern of dimpling  120  formed at the distal end. This circumferential pattern of dimpling may be similar to dimpling pattern  20  that is shown on prior art needle  10 . As stated above with regard to pattern  20  of  FIG. 1 , dimpling pattern  120  is visualized on the ultrasound monitor as a brightened portion that informs the operator of the general position of the distal portion of the needle. Dimpling pattern  20  on the prior art device does not inform the operator of the degree of rotation of the needle. As a result, the respective positions of distal tip  14  and bevel heel  18  cannot generally be distinguished in the prior art needle with sufficient clarity to ensure that the distal tip  14  is initially inserted into the target structure. 
         [0039]    In the example shown in  FIG. 3 , the position of the bevel heel  108  may be readily distinguished from the distal tip  104 . Unlike prior art needle  10  of  FIGS. 1 and 2 , needle  100  includes a second echogenic feature. In  FIG. 3 , this additional echogenic feature is an echogenic stripe  130 . Echogenic stripe  130  comprises a pattern of dimples extending longitudinally along all or a portion of the length of one longitudinal side  134 , or half, of needle  100 . In  FIG. 4  an imaginary plane, identified on the figure as P, extends along the longitudinal axis of needle  100  to distinguish longitudinal side  134  of the needle from the other longitudinal side  136 . As illustrated in  FIG. 3 , echogenic stripe  130  comprises a pattern of dimples, two to a row, extending in a proximal direction along needle longitudinal side  134 , from the most proximal circumferential row  123  of dimples  120 . In this example, stripe  130  is oriented such that it commences proximal of heel  108  of beveled needle opening  106 . 
         [0040]    By providing echogenic stripe  130  along a discrete longitudinal side of needle  100 , in this case on the longitudinal side  134  of elongated body  102  that includes heel  108 , the operator can readily distinguish one longitudinal side, or half, of the needle from the other on the ultrasound monitor. As a result, the operator is therefore able to readily determine the location of the heel. Armed with this knowledge, the operator can also readily determine the position, or more importantly, the rotational orientation of needle tip  104 . The operator can then readily determine from the image on the screen whether tip  104  must be rotated in order to lead into the vessel or other structure to be penetrated by needle tip  104 . If the needle must be rotated in order to maneuver tip  104  into position for initial entry, the image provided by the echogenic stripe enables the operator to determine when sufficient rotation has been carried out such that the tip is properly positioned for initial entry. 
         [0041]    Although the respective echogenic stripe  130  and circumferential pattern  120  have been described for simplicity as comprising a series of dimples, the use if this terminology is not meant to limit the echogenic feature to a particular geometric or structural configuration. Rather, those skilled in the art are aware that echogenicity may be imparted to a substrate in other ways. Thus, for example, the surface of the device may be constructed or treated in a manner such that a textured, patterned, indented, angled, or otherwise irregular surface may be formed thereon. As stated above, the dimpling may include dimples, divots, knurls, ridges, nubs, and like structures and configurations that are capable of enhancing the echogenicity as compared to a smooth or untreated surface for an otherwise similarly-sized/shaped object. 
         [0042]      FIGS. 5 and 6  illustrate another example of an echogenic medical device. In this example, echogenic needle  200  includes a generally elongated body  202  that extends to beveled opening  206  at distal end  203 . Beveled opening  206  is bordered at the distal end by distal tip  204  and at the proximal end by heel  208 . An outer sheath  201  may be provided as before. 
         [0043]    As in the previous example, needle  200  includes a circumferential dimpling pattern  220  and an echogenic longitudinal stripe pattern  230 . Longitudinal stripe pattern  230  may be provided along longitudinal side, or half,  234  of elongated body  202 . One or both of patterns  220 ,  230  may comprise a plurality of geometrically-shaped echogenic elements. In this example, dimpling pattern  220  comprises alternating rows of echogenic dimples having different geometric shapes, and extending around the circumference of distal end  203 . The alternating rows may comprise a sequential arrangement comprising a row  220   a  of generally circular dimples, a row  220   b  of generally triangular dimples, and a row  220   c  of generally square dimples. Similarly, longitudinal stripe pattern  230  may comprise respective longitudinal rows of generally circular dimples  230   a,  generally triangular dimples  230   b,  and generally square dimples  230   c  along longitudinal side  234 . In this manner longitudinal side  234  may be distinguished from longitudinal side  236 . 
         [0044]    By providing respective echogenic regions  220 ,  230  formed of sequential rows of echogenic elements of various geometrical configurations, a suitable ultrasound image may be achieved from a wider range of insertion angles of the needle when compared to an image resulting from a single configuration. 
         [0045]      FIGS. 7 and 8  illustrate another example of an echogenic medical device. In this example, echogenic needle  300  includes a generally elongated body  302  that extends to beveled opening  306  at distal end  303 . Beveled opening  306  is bordered at the distal end by distal tip  304  and at the proximal end by heel  308 . An outer sheath  301  may be provided to receive the proximal end of the needle body, as before. 
         [0046]    As in the previous examples, needle  300  includes a circumferential dimpling pattern  320  and an echogenic stripe pattern  330 . As in the example of  FIGS. 5 and 6 , one or both of patterns  320 ,  330  may comprise alternating rows of echogenic dimples having geometric shapes that differ from the shapes of the elements in another row. Unlike the previous example, at least some of the echogenic elements in any particular row may be rotated about their individual axes. Thus, as shown, dimpling pattern  320  may comprise alternating rows of echogenic dimples comprising a row  320   a  of generally circular dimples, a row  320   b  of generally triangular dimples, and a row  320   c  of generally square dimples. Similarly, longitudinal stripe pattern  330  may comprise respective longitudinal rows of generally circular dimples  330   a,  generally triangular dimples  330   b,  and generally square dimples  330   c.    
         [0047]    Rotating at least some of the echogenic elements around their respective axes as described enhances the echogenic signal from a respective row of the elements when compared to the same row without such rotation of the elements, thereby enhancing the visibility of stripe pattern  330 . 
         [0048]    Although the echogenic elements  120 ,  130 ,  220 ,  230 ,  320 ,  330  previously shown and described are either generally circular, generally triangular, or generally square, these are only examples of possible geometric configurations of the echogenic elements. Those skilled in the art will appreciate that other geometric shapes and configurations, such as hexagonal, pyramidal, etc., may be substituted for the shapes of the dimples shown and described, as long as the geometric shapes and configurations are capable of providing a suitable signal for ultrasound imaging. 
         [0049]    Similarly, although each of the rows in the examples shown and described includes echogenic elements having the same geometric configuration, this is not required in all instances. Therefore, it is permissible to include dimples of a plurality of geometric configurations in a single row, or in each row, at least some of which may be rotated about their respective axes when compared to other elements in the row, as described above. 
         [0050]      FIG. 9  illustrates another example of an echogenic medical device. In this example, echogenic needle  400  includes a generally elongated body  402  that extends to beveled opening  406  at distal end  403 . Beveled opening  406  is bordered at the distal end by distal tip  404  and at the proximal end by heel  408 , as in the previous examples. An outer sheath  401  may be provided as before. 
         [0051]    Needle  400  includes a first circumferential dimpling pattern  420  as before, and includes one or more sets of additional dimpling patterns. In this example, needle  400  includes second and third dimpling patterns  430 ,  440 , respectively. Dimpling patterns  420 ,  430 ,  440  may be formed of echogenic elements of a type described above. In this example, the echogenic elements of the first circumferential pattern  420  are generally circular. The echogenic elements of the second circumferential pattern  430  are generally triangular. The echogenic elements of the third circumferential pattern are generally square. If desired, at least some of the echogenic elements may be rotated in any fashion about their axes. See, e.g., generally triangular elements  430  in the example shown. Those skilled in the art will appreciate that the specific geometric configurations of the echogenic elements are not restricted to the elements shown in this example, and may be varied as desired. Providing echogenic bands of different configurations spaced longitudinally along the length of the needle allows the operator to better determine penetration depth, and provides a scale along the shaft of the needle composed of various shapes and angles. 
         [0052]      FIG. 10  illustrates still another example of an echogenic medical device. Echogenic needle  500  includes a generally elongated body  502  that extends to beveled opening  506  at distal end  503 . Beveled opening  506  is bordered at the distal end by distal tip  504  and at the proximal end by heel  508 . An outer sheath  501  may be provided as before. A circumferential pattern of dimpling  520  is formed at the distal end. In this example, dimples  520  extend inwardly into the surface of the needle in a manner to comprise one or more wall angles 1, 2 , etc. In the example shown, generally-triangular dimples extend inwardly into the matrix of the needle in a generally pyramidal configuration to create the wall angles 1  and  2 . 
         [0053]      FIG. 11  is an enlarged view of one of dimples  520 , in this case dimple  520   a.  Lines A-A and B-B are provided to illustrate the orientation of angles 1  and  2 .  FIG. 12  is a tangential sectional view of needle  500  at dimple  520   a.  This tangential cross-section view is taken along A-A of  FIG. 11 , and illustrates angle 1 .  FIG. 13  is an axial sectional view along the circumference of needle  500  at dimple  520   a.  This axial sectional view is taken along B-B of  FIG. 11 , and illustrates angle 2 . Those skilled in the art may adjust the configuration of the dimples, and the respective wall angles, as desired to enhance or otherwise modify echogenicity. 
         [0054]    In addition to the dimples and related structures that may impart echogenicity to a medical device as described, echogenicity may be also imparted to the device in a manner other than by forming the echogenic elements into or onto the surface of the device in a manner described above. For example, more, or fewer, rows of dimples, etc., may be applied to form longitudinal stripes, such as stripes  130 ,  230 ,  330 , and the other echogenic structures as shown and described hereinabove. In addition, the rows need not necessarily be adjacent as shown in  FIGS. 3 ,  5 , and  7 , and instead can be spaced or otherwise positioned in a manner such that a discernable and/or distinguishable echogenic pattern may be observed. Further, instead of longitudinal rows, other patterns can be substituted, such as spiral rows, broken lines, etc., along the longitudinal side of the needle. 
         [0055]    Those skilled in the art will appreciate that since an objective is to distinguish an amount of rotation of the device, other patterns capable of providing such orientation may be substituted. Preferably, however, all or most of the pattern will extend along a particular longitudinal side of the device. This arrangement provides a very favorable frame of reference, so that the rotational orientation of the medical device can be readily determined. Those skilled in the art will appreciate that any irregularities or other modification of the substrate should be carried out in a manner that does not adversely affect the mechanical properties of the substrate in any material fashion. 
         [0056]      FIG. 14  is another example of an echogenic medical device according to the present invention.  FIG. 14  illustrates a medical device, such as curved catheter  600 , having an echogenic ribbon  610  applied along a length of the catheter. In  FIG. 14 , the echogenic ribbon is disposed along an outer surface of the curved portion.  FIG. 15  illustrates the curved catheter rotated 90 degrees from the view of  FIG. 14  so that the top surface of the curved catheter can be observed. 
         [0057]    In this embodiment, rather than deforming the surface of the catheter to form the series of irregularities as described, one or more lengths of echogenic ribbon  610  may be provided along all, or a portion, of the length of catheter  600 . Ribbon  610  may be formed of the same or a similar composition as catheter  600 , such as a metal or a metal alloy, and deformations (e.g., dimples) are disposed along the surface of the ribbon. The deformations may be formed in the same manner as the deformations on the structures previously described, and may be dispersed along the surface of ribbon  610  in a manner such that an operator may discern the orientation of the catheter. Although catheter  600  and ribbon  610  have been described in this example as being formed of the same or a similar material, those skilled in the art will appreciate that this need not be the case, as long as suitable means (e.g., an adhesive or bonding) are provided for securing the ribbon along the surface of the catheter. 
         [0058]    Although ribbon  610  is shown in  FIGS. 14 and 15  as a continuous ribbon extending along the length of catheter  600 , other configurations are possible. For example, if desired, multiple shorter ribbons or similar structures can be applied to, or wrapped around, catheter  600 . This arrangement may also provide additional flexibility to the echogenic portion of the feeding tube. Alternatively, echogenicity may be imparted by surface deformation or irregularity, or by modifying the matrix of the substrate. As still another alternative, ribbon  610  can be embedded into the wall of catheter  600 , and a plastic can be extruded or otherwise applied over the ribbon and the catheter. Those skilled in the art will appreciate that although a curved medical device  600  is illustrated in the example, this is merely one example of a medical device that may be modified by application of ribbon  610 , and that a modification of devices of other configurations, such as straight, helical, etc. is also contemplated. 
         [0059]    In addition to the foregoing, there are additional ways of providing echogenicity to a substrate of a type that will result in enhanced scatter and/or reflectance of ultrasound signals, and that may be substituted for the surface techniques described above. For example, an echogenic coating can be applied to a designated length of the substrate, such as the length of longitudinal echogenic stripes  130 ,  230 ,  330 . Suitable echogenic coatings are described in, for example, U.S. Pat. Nos. 6,506,156 and 6,106,473, both incorporated by reference herein. 
         [0060]    As yet another variation, instead of surface modification or utilizing a separate echogenic ribbon, stripe, coating, etc., the substrate may be formed to have an echogenic material incorporated into all or any designated portion of its matrix. Thus, for example, a known material for imparting echogenicity, such as glass spheres, echogenic metal or alloys (e.g., tungsten), etc., may be incorporated into the matrix during formation of the substrate, e.g., into a polymer matrix during substrate formation. Preferably, the materials (e.g., the glass spheres) will only be incorporated into the distal portion or other specifically designated portion of the substrate, and will be incorporated in a manner such that a distinct echogenic pattern is provided along the designated substrate portion, such as longitudinal side  134  ( FIGS. 3 and 4 ). Alternatively, a portion (e.g., the distal portion) of the substrate can be formed to have the desired echogenic pattern, and this portion can then be affixed (e.g., via heat bonding, adhesion, etc.) to another portion (e.g., the proximal portion or an intermediate portion) of the substrate. Once this substrate is formed, there would generally be no further need to add other irregularities, materials, etc., to enhance echogenicity, as sufficient echogenicity for visualization under ultrasound is provided by the matrix materials. 
         [0061]    It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.