JPH0593410U - Ultrasound imaging catheter - Google Patents

Abstract

(57) [Abstract] [Purpose] Significantly improve the shallow observation depth inherent in a small-diameter ultrasonic imaging catheter. An ultrasonic imaging catheter with high resolution is provided. An outer tube (12) to be inserted into a body cavity, and an outer tube (12) that is swingably supported in the vicinity of the tip of the outer tube (12) in a plane along the longitudinal direction of the outer tube (12). A vibrator 14 having an opening larger than the diameter of the tube 12, a transmission wire 18 which is disposed in the outer tube 12 along the extending direction thereof, and which reciprocates or rotates with respect to the outer tube 12, and a vibration. Child 1
4 is arranged at the rear portion of the transmission wire 18 and converts the reciprocating motion or the rotational motion of the transmission wire 18 into the swing motion of the oscillator 14.
9 and 9.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a catheter-type small-diameter ultrasonic probe that can be inserted into a blood vessel. In particular, it enables the expansion of the observation depth (for ultrasonic diagnostic equipment using the ultrasonic pulse echo method). Regarding catheters.

[0002]

[Prior Art]

 The ultrasonic diagnostic apparatus is one of the image diagnostic apparatuses that have become very popular in recent years. The target of diagnosis is almost the whole human body, and many probes (linear probe, convex probe, sector probe, etc.) for observing internal organs from outside the body have been put to practical use. Recently, intracavity probes (transrectal probe, transluminal probe, and transesophageal probe) that allow direct observation of the target organ from inside the body have been developed, enabling more precise observation and diagnosis.

Further, at present, a small-diameter probe that can be inserted into a forceps port of an endoscope or a blood vessel has been developed, and precise diagnosis of the stomach, gallbladder, pancreas, etc. under observation with an endoscope and X Observation of coronary cross-section under fluoroscopy is progressing. Currently, the smallest probe that can be inserted into a blood vessel is one that uses an ultrasonic wave of 30 MHz at a diameter of just over 1 mm.

The conventional structure of a catheter-type small-diameter ultrasonic probe that can be inserted into a blood vessel (hereinafter referred to as an ultrasonic imaging catheter) is roughly classified into FIGS. 14 (a), (b), (c). ) There are three known types. 14 (a) and 14 (b) show the structure of a radial scanning type ultrasonic imaging catheter using a mechanical scanning method, and FIG. 14 (a) shows a structure in which a transducer 101 is directly rotated by a drive shaft 103. In FIG. 4B, the transducer 101 is fixed and the opposing acoustic reflecting mirror 102 is rotationally scanned by the rotary drive shaft 103. In all of these, the ultrasonic beam 110 is rotationally scanned in a direction perpendicular to the catheter 104 to obtain a tomographic image. That is, when the catheter 104 is inserted into a blood vessel, the cross section (circular slice) of the blood vessel can be observed as an image.

[0005]

[Problems to be solved by the device]

 However, in the conventional example shown in FIG. 14 (b), the opening of the oscillator 101 is limited by the diameter of the catheter 104, and in the example shown in FIG. 14 (a), The aperture S that determines the resolution in the slice thickness direction of the tomographic plane is not limited by the diameter of the catheter 104, but the aperture L that determines the azimuth resolution of the tomographic image plane is limited by the diameter of the catheter 104. I will end up.

Therefore, when the catheter 104 has a small diameter, for example, about 1 mm so that it can be inserted into a blood vessel, the opening of the vibrator 101 also becomes 1 mm or less. Due to the principle of sound waves, ultrasonic waves transmitted from a small aperture have a poorer directivity than ultrasonic waves transmitted from a large aperture, and the ultrasonic beam immediately diffuses. Therefore, in order to improve the directivity of the ultrasonic beam and the resolution of the image when the ultrasonic beam is generated by the transducer with such a small aperture, in principle, the frequency of the ultrasonic beam should be set higher. Must be set to a higher frequency. For this reason, the frequency of the ultrasonic imaging catheter with a diameter of about 1 mm, which has been put into practical use, is set to a high frequency of about 20 to 30 MHz.

The relationship between aperture, resolution and frequency is described in detail in Japanese Patent Application Laid-Open No. 60-18159 filed by the applicant of the present application. As described above, in a radial scanning type small-diameter imaging catheter, a high frequency of about 20 to 30 MHz must be used, and therefore the observation depth (the ultrasonic beam reach depth) is extremely shallow (about 5 mm). Therefore, the target of diagnosis is extremely limited to the vicinity of the blood vessel cross section. Of course, if the diameter of the catheter is made thicker, a large opening can be made, so a frequency of 20 MHz to 10 MHz, which is a lower frequency, can be used, and the diagnostic depth can be expanded, but the diameter of the catheter can be increased to 2 to 3 mm. It becomes thick and it becomes difficult to insert it into the blood vessel.

In addition, as shown in FIG. 14C, a large number of rectangular transducers 101 are arranged around a catheter, and the ultrasonic beam 110 is radially scanned by an electronic scanning method. .. Also in this method, the lateral resolution depends on the opening limited by the diameter of the catheter 104. Furthermore, this method has a principle problem that a tomographic image with good resolution cannot be obtained unless the number of transducers 101 arranged on the outer circumference of the catheter 104 is increased (for example, 64 elements or more). , It is extremely difficult to manufacture. It is also necessary to provide a switching circuit for controlling the electronic scan at the tip portion 105 of the catheter 104 (when the switching circuit is outside the catheter, it is necessary to pass as many leads as the number of elements into the catheter). ) In any case, it is extremely difficult to reduce the diameter, and it cannot be said to be a practical method.

One method for solving the above problems is to extend the aperture of the transducer in the longitudinal direction of the catheter and perform sector scanning of the transducer along the plane including the central axis of the catheter. There are possible ways to do it. In this case, the aperture in the scanning direction is not limited by the diameter of the catheter, so that lower frequencies can be used and the observation depth can be deeper without reducing the resolution.

As a mechanism for sector-scanning the transducer along the plane including the central axis of the catheter in this way, for example, a mechanism disclosed in Japanese Patent Publication No. 57-61417 or Japanese Patent Publication No. 63-145640. The one disclosed in the publication is known. However, among the above-mentioned mechanisms, the mechanism disclosed in Japanese Patent Publication No. 57-61417 discloses a mechanism, such as a solenoid coil 128, an armature 124, and a rotating body 120, which is provided below a vibrator 122 as shown in FIG. Since the members are provided, an extra space for arranging these mechanical members is required in the radial direction of the catheter. As a result, the outer diameter of the catheter is increased in principle, which is a structure that is essentially unsuitable for small diameter catheters. Even with this structure, even if the opening of the transducer is made large along the longitudinal direction of the catheter as shown in FIG. 16, the sector scan angle is extremely small due to the presence of the above-mentioned mechanical member. .. That is, this structure can be applied to a rectal probe or a body cavity probe, but cannot be applied to a probe having a small diameter that can be inserted into a blood vessel.

Further, the mechanism disclosed in Japanese Patent Laid-Open No. 63-145640 is provided with a swingable rotatable member at the tip of a catheter, and an electronic scanning type probe is provided on the rotatable member. It is attached. Similar to the mechanism disclosed in Japanese Patent Publication No. 57-61417, this structure also has a drive mechanism below the transducer (probe). Since it requires a large space, the outer diameter of the catheter tends to be inherently thick, which is not suitable for a catheter with a small diameter that can be inserted into a blood vessel.

[0012] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize a shallow observation depth that is inherently possessed by a small-diameter ultrasonic imaging catheter. It is to provide an ultrasonic imaging catheter that has a large improvement, has a deep observation depth even with a small diameter, and has good image resolution.

[0013]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems and to achieve the object, the ultrasonic imaging catheter of the present invention has an outer tube part to be inserted into a body cavity and a longitudinal part of the outer tube part near the tip part of the outer tube part. A vibrator which is swingably supported in a plane along the direction and has an opening larger than the diameter of the outer tube along the longitudinal direction of the outer tube; And a transmission wire that reciprocates or rotates with respect to the outer tube portion, and a reciprocating motion or rotational movement of the transmission wire that is disposed at the rear portion of the vibrator, and is converted into a swing motion of the vibrator. And a conversion mechanism for converting.

[0014]

[Action]

 As described above, since the ultrasonic imaging catheter according to the present invention is constructed, the reciprocating motion or the rotary motion of the transmission wire is converted into the diameter of the outer tube portion through the conversion mechanism provided behind the transducer. By converting into a swinging motion of a transducer with a larger opening, it is possible to scan the transducer in the direction of the larger opening, but the storage space for the conversion mechanism is increased in the radial direction of the outer tube. Since it is not necessary, it is possible to provide an ultrasonic imaging catheter that has a large observation depth even with a small diameter and has good image resolution.

[0015]

【Example】

 Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing the structure of an ultrasonic imaging catheter according to an embodiment.

In FIG. 1, an ultrasonic imaging catheter 10 (hereinafter, simply referred to as a catheter) is inserted into a body cavity or a blood vessel from its tip 10a, and the structure around the body cavity or the blood vessel is ultrasonically detected. It is for exploring. An ultrasonic oscillator 14 is arranged in the vicinity of the distal end inside the outer tube 12 forming the outer shell of the catheter 10, and the ultrasonic oscillator 14 is attached to the substrate 30. The substrate 30 is rotatably supported by a rotating shaft 16 in a plane along the longitudinal direction of the catheter 10. Behind the ultrasonic transducer 14, a flexible drive wire 18 arranged along the longitudinal direction of the outer tube 12 is arranged, and the drive wire 18 is arranged at the rear end of the catheter 10. By a driving device (not shown), a reciprocating movement along the longitudinal direction of the outer tube 12 (direction of arrow a) or a rotational movement about the central axis of the outer tube 12 (direction of arrow b) is performed. There is. Between the drive wire 18 and the ultrasonic oscillator 14, the reciprocating motion or the rotational motion of the drive wire 18 is converted into the swinging motion of the ultrasonic vibrator 14 around the rotation axis 16 (direction of arrow c). A conversion mechanism 19 is arranged. Therefore, the ultrasonic transducer 14 is driven by a driving device (not shown) so that the sector operation is performed over the range of the arrow d in the side view direction with respect to the longitudinal direction of the catheter 10.

The ultrasonic transducer 14 has an opening width of A in the longitudinal direction of the catheter 10 and an opening width of F in the radial direction of the catheter 10, as shown in FIGS. have. The radial opening width F of the catheter 10 is necessarily limited by the inner diameter D 1 of the catheter 10, and the opening width F is set to a value slightly smaller than this inner diameter D 2. On the other hand, the opening width A in the longitudinal direction of the catheter 10 is not limited to the inner diameter D of the catheter 10 and can be set larger than the inner diameter D of the catheter 10. As described above, by increasing the opening width A along the longitudinal direction of the catheter 10, that is, the scanning direction of the ultrasonic transducer 14, it becomes difficult for the ultrasonic waves to diffuse. Therefore, in the sector operation indicated by the range of arrow d. The lateral resolution is improved. This improved azimuth resolution can ensure the required resolution even at lower frequencies, so lower frequencies can be used to increase the depth of arrival of the ultrasonic beam. If the arrival depth of the ultrasonic beam increases, the observation depth of the catheter 10 becomes deeper, and it becomes possible to perform observation in a wider range.

The relationship between the opening width A of the ultrasonic transducer 14, the sector scanning angle α, and the inner diameter D of the catheter 10 in this embodiment is expressed by the following equation. α = 2 · sin ⁻¹ (D / A) When this relationship is expressed in a graph, it becomes as shown in FIG. According to FIG. 4, when the opening width A is twice the inner diameter D of the catheter 10, a scanning angle of about 60 ° is obtained, and even when the opening width A is four times the inner diameter D, it is about 30 °. It can be seen that the scanning angle of is obtained.

Next, FIG. 5 is a diagram showing a first modification of the embodiment. The same parts as those in the embodiment are designated by the same reference numerals and the description thereof will be omitted. In FIG. 5, another ultrasonic transducer 22 is provided on the back surface of the ultrasonic transducer 14 with the backing layer 20 interposed therebetween. If sector scanning is simultaneously performed by these two ultrasonic transducers 14 and 22, the range shown by arrow d and the tomographic image within the range shown by arrow e can be obtained at the same time, and the observation range can be further expanded. You can

FIG. 6 is a diagram showing a second modification of the embodiment. In this second modification, the ultrasonic transducer 14 of the embodiment is replaced with an array vibrating element 26 in which small vibrating elements 24 are arranged in an array as shown in FIGS. 6 and 7. is there. When the array vibrating element 26 is used in this way, the electronic focusing technique can be used at the time of transmitting and receiving ultrasonic waves, so that the resolution of images can be improved. In particular, in the case of a catheter with a large opening and a large observation depth, as in this embodiment, it is possible to focus on a deep portion of the affected area by using the electronic focusing technique. It is possible to observe clearly. Further, the array transducer 26 can be applied to the first modification shown in FIG.

Furthermore, various modifications such as improving the convergence of ultrasonic waves can be considered by using the ultrasonic vibrator as a concave vibrator. Next, the structure of the conversion mechanism 19 will be described. FIG. 8 is a diagram showing the structure of the conversion mechanism 19 according to the first embodiment. In FIG. 8, the ultrasonic transducer 14 is arranged on a substrate 30 that is rotatably mounted around a rotary shaft 16. As shown in FIG. 9, a slide groove 30a extending in the width direction of the substrate 30 is formed at the rear end of the substrate 30. On the other hand, the tip portion 18a of the drive wire 18 is bent as shown in FIG. 8, and a spherical projection portion 18b is formed on the tip portion thereof (FIG. 10). Then, as shown in FIG. 10, the protrusion 18b enters the substrate 30 through the slide groove 30a. In the conversion mechanism 19 configured as above, when the drive wire 18 rotates as shown by the arrow b in FIG. Exercise. With this movement, the protrusion 18b slides along the slide groove 30a as shown in FIGS. 9A to 9C, and the substrate 30 swings around the rotary shaft 16. Becomes

Next, FIG. 11 is a view showing the structure of the second embodiment of the conversion mechanism 19. In FIG. 11, one end of a link member 34 is rotatably attached to the tip of the substrate 30 via a hinge 32. The other end of the link member 34 is rotatably attached to the tip of the drive wire 18 via a hinge 35. Therefore, when the drive wire 18 reciprocates in the direction of arrow a, the link member 34 rotates at a rotation angle of 90 ° or less as the drive wire moves, and the substrate 30 swings as indicated by arrow c. Do exercise.

FIG. 12 shows a structure of a modification of the second embodiment, and shows a case where a link member 38 is attached to the rear end portion of the substrate 30 via a hinge 36. In this structure as well, the drive wire 18 reciprocates in the direction of the arrow a in exactly the same manner as in the second embodiment, so that the substrate 30 oscillates as shown by the arrow c. Next, FIG. 13 is a diagram showing the structure of the third embodiment of the conversion mechanism 19.

In FIG. 13, the substrate 40 to which the ultrasonic transducer 14 is attached is rotatably supported by the rotating shaft 41 at the front end portion 40 a thereof with respect to the outer tube 12. A sliding pin 42 is attached to the rear end portion 40b of the substrate 40. On the other hand, a slide rail 44 having a substantially arcuate groove portion 44a is attached to the distal end portion of the drive wire 18 in a state of extending in the vertical direction. In the conversion mechanism 19 configured in this manner, when the drive wire 18 reciprocates in the direction of arrow a, the sliding pin 42 slides vertically along the arcuate groove portion 44a, and accordingly. Thus, the substrate 40 makes a swinging motion around the rotation shaft 41.

Of the above embodiments, the most preferred one is the first embodiment. In the first embodiment, since the ultrasonic transducer 14 can be oscillated by the rotational movement of the drive wire 18, the conventional radial scan method as shown in FIGS. 14 (a) and 14 (b) is used. The drive mechanism of the ultrasonic diagnostic apparatus using the small-diameter probe can be used as it is. Therefore, by using one ultrasonic diagnostic equipment main unit and replacing only the probe, it is possible to support a wide range of diagnosis from observation of the vicinity of blood vessels to observation of deep organs, which is practically excellent. ..

It should be noted that the present invention can be applied to modifications and variations of the above embodiments without departing from the spirit of the invention.

[0027]

[Effect of the device]

 As described above, according to the ultrasonic imaging catheter of the present invention, the reciprocating motion or rotating motion of the transmission wire is larger than the diameter of the outer tube portion via the conversion mechanism provided behind the transducer. By converting the oscillator with the opening into the oscillating motion, it is possible to scan the oscillator in the direction in which the opening is large, but a space for the conversion mechanism is required in the radial direction of the outer tube. Since it is eliminated, it is possible to provide an ultrasonic imaging catheter which has a deep observation depth even with a small diameter and has good image resolution.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the structure of an ultrasonic imaging catheter according to an embodiment.

FIG. 2 is a cross-sectional view of FIG. 1 viewed from the right side.

FIG. 3 is a plan view showing the shape of an ultrasonic transducer.

FIG. 4 is a graph showing the relationship between the opening width of the ultrasonic transducer, the sector scan angle, and the inner diameter of the catheter.

FIG. 5 is a diagram showing a first modification of the embodiment.

FIG. 6 is a diagram showing a second modification of the embodiment.

FIG. 7 is a plan view showing the shape of an ultrasonic transducer according to a second modification.

FIG. 8 is a view showing the structure of the first example of the conversion mechanism.

FIG. 9 is a diagram showing how the ultrasonic transducer oscillates.

FIG. 10 is a side sectional view of a rear end portion of a substrate.

FIG. 11 is a diagram showing a structure of a second example of the conversion mechanism.

FIG. 12 is a diagram showing the structure of a third embodiment of the conversion mechanism.

FIG. 13 is a diagram showing the structure of a fourth example of the conversion mechanism.

FIG. 14 is a diagram showing the structure of a conventional small-diameter ultrasonic imaging catheter.

FIG. 15 is a diagram showing an example of a drive mechanism for a conventional ultrasonic transducer.

FIG. 16 is a diagram showing a case where the ultrasonic transducer has a large opening in FIG.

[Explanation of symbols]

 10 Ultrasonic Imaging Catheter 12 Outer Tube 14 Ultrasonic Transducer 16 Rotating Shaft 18 Drive Wire 19 Conversion Mechanism 20 Backing Layer 22 Ultrasonic Transducer 24 Vibrating Element 26 Array Vibrating Element 30 Substrate 32 Hinge 34 Link Member 35 Hinge 36 Hinge 38 Link member 40 Substrate 41 Rotating shaft 42 Sliding pin 44 Slide rail

Claims (1)

[Scope of utility model registration request] 1. An outer tube part to be inserted into a body cavity, and a longitudinal part of the outer tube part, which is swingably supported near a tip part of the outer tube part in a plane along the longitudinal direction of the outer tube part. A vibrator having an opening larger than the diameter of the outer tube portion along the direction, and arranged in the outer tube portion along the extending direction thereof and reciprocating or rotating with respect to the outer tube portion. An ultrasonic imaging catheter comprising: a transmission wire; and a conversion mechanism, which is disposed at a rear portion of the transducer and converts a reciprocating motion or a rotational movement of the transmission wire into a swing motion of the transducer.