JPH08275946A - Ultrasonic imaging catheter - Google Patents

Abstract

PURPOSE: To provide an ultrasonic imaging catheter which has large observing depth even in a small diameter and has good image resolving power, by improving greatly the shallowness of observation depth which is an intrinsic nature the ultrasonic imaging catheter of the small diameter has. CONSTITUTION: This ultrasonic imaging catheter is provided with an outer tube 12 which is inserted into a body cavity, a vibrator 14 which is supported swingingly on a face along the longitudinal direction of the outer tube 12 near the head part of the outer tube 12 and has a larger opening than the diameter of the outer tube 12 along the longitudinal direction of the outer tube 12, a transmission wire 18 which is arranged along the extending direction of the outer tube 12 therein and by which reciprocating motion or rotating motion is performed in relation to the outer tube 12, and a converting mechanism 19 which is arranged on the rear part of the vibrator 14 and by which the reciprocating motion or rotating motion of the transmission wire 18 is converted into a swinging motion of the vibrator 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a catheter type ultrasonic probe having a small diameter which can be inserted into a blood vessel, and in particular, enables extension of the observation depth (an ultrasonic diagnostic apparatus using an ultrasonic pulse echo method. Ultrasonic imaging catheter).

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus is one of the image diagnostic apparatuses that have become very popular in recent years. The diagnosis target is almost the whole body of the human body, and many probes (linear probe, convex probe, sector probe, etc.) for observing internal organs and the like from outside the body have been put to practical use. In addition, recently, a body cavity probe (transrectal probe, transcavity probe, or transesophageal probe) that allows direct observation of a target organ from inside the body has been developed, which enables more precise observation and diagnosis.

Further, at present, a small-diameter probe that can be inserted into the forceps mouth 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-rays are being performed. This is a situation where the observation of coronary artery cross-section under fluoroscopy is progressing.
At present, as a minimum diameter probe that can be inserted into a blood vessel, one using an ultrasonic wave of 30 MHz at a diameter of slightly over 1 mm is known.

The conventional structure of a catheter type small-diameter ultrasonic probe (hereinafter referred to as an ultrasonic imaging catheter) that can be inserted into a blood vessel is roughly classified into FIG.
Three types are known as shown in (a), (b) and (c).

FIGS. 14 (a) and 14 (b) show the structure of a radial scanning type ultrasonic imaging catheter using a mechanical scanning method. FIG. 14 (a) shows a transducer 101 directly mounted on a rotary drive shaft 103. Those that rotate and scan,
(B) is an acoustic reflecting mirror 1 in which the oscillator 101 is fixed and facing each other.
02 is rotationally scanned by the rotary drive shaft 103. In all of these, the ultrasonic beam 110 is rotationally scanned in the 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.

[0006]

However, among the above-mentioned conventional examples, the one shown in FIG.
The opening of the oscillator 101 is limited by the diameter of the catheter 104, and in the case shown in FIG.
Aperture S that determines the resolution in the slice thickness direction of the slice plane
Is not limited to the diameter of the catheter 104,
The aperture L that determines the lateral resolution of the tomographic image plane is limited by the diameter of the catheter 104.

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 vibrator 10
The opening of 1 also becomes 1 mm or less. According to the principle of sound waves, ultrasonic waves transmitted from a small opening have a property that directivity is inferior to that of ultrasonic waves transmitted from a large opening 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 vibrator having such a small aperture, in principle, the ultrasonic beam The frequency must be set to a higher frequency. For this reason, the frequency of the ultrasonic imaging catheter having 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.

Regarding the relationship between the aperture, the resolution and the frequency,
Japanese Patent Application Laid-Open No. 60-18159 filed by the applicant of the present application
It is described in detail in the publication.

As described above, in the 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 arrival depth of the ultrasonic beam) is extremely shallow (about Therefore, the diagnosis target is very limited to the vicinity of the blood vessel cross section. Of course, if the diameter of the catheter is made large, a large opening can be made, so that the frequency is lower.
A frequency of about 10 to 10 MHz can be used, and the diagnostic depth is expanded, but the diameter of the catheter is increased to about 2 to 3 mm, which makes it difficult to insert the catheter into a blood vessel.

In the structure shown in FIG. 14C, a large number of rectangular vibrators 101 are arranged around the catheter,
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. Further, 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's extremely difficult. It is also necessary to provide a switching circuit for controlling the electronic scan on the tip portion 105 of the catheter 104 (if 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,
Not a practical method.

As one method for solving the above-mentioned problems, the opening of the vibrator is extended in the longitudinal direction of the catheter, and the vibrator is sector-scanned along a plane including the central axis of the catheter. A method can be considered. In this case,
Since the aperture in the scan direction is not limited by the diameter of the catheter, lower frequencies can be used and observation depth can be deeper without loss of resolution.

As a mechanism for sector-scanning the transducer along the plane including the central axis of the catheter, for example,
The one disclosed in JP-B-57-61417 and the one disclosed in JP-A-63-145640 are known.

However, among the above mechanisms, Japanese Patent Publication No.
The mechanism disclosed in Japanese Patent Publication No. 7-61417 is shown in FIG.
Since mechanical members such as the solenoid coil 128, the armature 124, and the rotating body 120 are provided below the vibrator 122 as shown in FIG. 3, a space for arranging these mechanical members is provided in the radial direction of the catheter. Extra needed. As a result, the outer diameter of the catheter is increased in principle, which is essentially unsuitable for a small-diameter catheter. 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, even if this structure can be applied to a rectal probe or a body cavity probe,
It cannot be applied to a probe having such a small diameter that it can be inserted into a blood vessel.

In the mechanism disclosed in Japanese Patent Laid-Open No. 63-145640, a swingable rotatable member is provided at the tip of the catheter, and an electronic scanning type probe is provided on the rotatable member. It is attached. This structure is similar to the mechanism disclosed in Japanese Patent Publication No. 57-61417.
Since the drive mechanism exists under the transducer (probe), an extra space is required in the radial direction of the catheter by the amount of this drive mechanism, and therefore the outer diameter of the catheter is essentially thick. It is not suitable for a catheter with a small diameter that tends to be inserted into a blood vessel.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to significantly reduce the depth of observation that a small-diameter ultrasonic imaging catheter essentially has. The ultrasonic imaging has a large observation depth even with a small diameter and good image resolution.
To provide a catheter.

[0017]

In order to solve the above-mentioned problems and achieve the object, an ultrasonic imaging catheter of the present invention has an outer tube portion to be inserted into a body cavity and a tip of the outer tube portion. A vibrator having an opening larger than the diameter of the outer tube portion along the longitudinal direction of the outer tube portion and swingably supported in the plane of the outer tube portion in the vicinity of the outer tube portion; A transmission wire that is disposed in the tube portion along the extension direction thereof and that reciprocates or rotates with respect to the outer tube portion; and a reciprocating movement or rotation motion of the transmission wire that is disposed at the rear portion of the vibrator. To a swing motion of the oscillator.

As described above, since the ultrasonic imaging catheter according to the present invention is constructed, the reciprocating motion or rotary motion of the transmission wire is transferred to the outer tube via the conversion mechanism provided behind the vibrator. By converting the oscillator into an oscillating motion that has an opening that is larger than the diameter of the section, the transducer can be scanned in the direction in which the opening is larger, but the conversion mechanism is accommodated in the radial direction of the outer tube section. Since no space is required, it is possible to provide an ultrasonic imaging catheter having a small observation diameter, a deep observation depth, and good image resolution.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic view showing the structure of an ultrasonic imaging catheter according to one 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 searched by ultrasonic waves. It is for.

An outer tube 12 forming the outer shell of the catheter 10.
An ultrasonic transducer 14 is arranged near the tip of the inside of the ultrasonic transducer, and the ultrasonic transducer 14 is attached to the substrate 30. The substrate 30 is rotatably supported by the 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.
A drive device (not shown) arranged at the rear end of the outer tube 1
2 reciprocating movement along the longitudinal direction (arrow a direction) or rotational movement about the central axis of the outer tube 12 (arrow b direction)
It is designed to do. Between the drive wire 18 and the ultrasonic transducer 14, the reciprocating movement or the rotational movement of the drive wire 18 is converted into a swinging movement (in the direction of arrow c) around the rotation axis 16 of the ultrasonic transducer 14. A conversion mechanism 19 is arranged. Therefore, the ultrasonic transducer 14 is driven by a drive 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.

As shown in FIGS. 1, 2 and 3, the ultrasonic transducer 14 has an opening width A in the longitudinal direction of the catheter 10 and an opening width F in the radial direction of the catheter 10. have. The radial opening width F of the catheter 10 is necessarily limited by the inner diameter D of the catheter 10, and the opening width F
Is set to a value slightly smaller than this inner diameter D.
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 larger than the inner diameter D of the catheter 10. in this way,
By increasing the opening width A along the longitudinal direction of the catheter 10, that is, the scanning direction of the ultrasonic transducer 14, the ultrasonic waves are less likely to diffuse, so that the azimuth resolution in the sector operation shown by the arrow d is improved. To be done. This improved lateral resolution ensures the required resolution even at lower frequencies, so lower frequencies can be used to increase the reach of the ultrasonic beam. If the arrival depth of the ultrasonic beam increases, the observation depth by the catheter 10 becomes deeper, and it becomes possible to observe a wider range.

The opening width A of the ultrasonic transducer 14, the sector scan angle α, and the catheter 10 in this embodiment are as follows.
The relation with the inner diameter D of is expressed by the following equation.

Α = 2 · sin ⁻¹ (D / A) This relationship is shown in the graph 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.
It can be seen that a scanning angle of about 30 ° can be obtained even when is 4 times the inner diameter D.

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 a backing layer 20 interposed therebetween. These two ultrasonic transducers 1
If the sector scanning is performed simultaneously with 4 and 22, tomographic images in the range indicated by the arrow d and the range indicated by the arrow e can be obtained at the same time, and the observation range can be further expanded.

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. It is a thing. By using the array vibrating element 26 in this way, the electronic focusing technique can be used when transmitting and receiving ultrasonic waves, and therefore the resolution of the image can be improved. In particular, as in this embodiment, in a catheter having a large observation depth to deepen the observation depth, it is possible to focus on a deep portion of the affected area by using the electronic focusing technique, so that the deep portion can be clearly seen. It becomes possible to observe. The array vibrator 26 can also be applied to the first modification shown in FIG.

Furthermore, various modifications are conceivable, such as using an ultrasonic vibrator as a concave vibrator to improve the convergence of ultrasonic waves.

Next, the structure of the conversion mechanism 19 will be described.

FIG. 8 is a view 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 rotatably mounted around a rotary shaft 16. As shown in FIG. 9, a slide groove 30 a 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 protrusion 18b is formed at the tip of the bent portion (see FIG. 1).
0). 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 described above, when the drive wire 18 rotates as shown by the arrow b in FIG.
The tip portion 18a of the drive wire 18 whirls around the central axis of the drive wire 18. With this movement, the protrusion 18b is, as shown in FIGS. 9 (a) to 9 (c),
By sliding along the slide groove 30a, the substrate 30 swings around the rotating shaft 16.

Next, FIG. 11 is a diagram showing the structure of the second embodiment of the conversion mechanism 19.

In FIG. 11, the tip of the substrate 30 is
One end of the link member 34 is rotatably attached via the hinge 32. The other end of the link member 34 is
It is rotatably attached to the distal end portion 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 rotationally moves within a rotation angle of 90 ° as the drive wire moves,
The substrate 30 makes an oscillating motion as shown by the arrow c.

FIG. 12 shows the structure of a modification of the second embodiment, and shows a case where a link member 38 is attached to the rear end of the substrate 30 via a hinge 36. Also in this structure, 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 with respect to the outer tube 12 at the tip portion 40a thereof. A sliding pin 42 is provided on the rear end portion 40b of the substrate 40.
Is attached. On the other hand, the slide rail 4 having a substantially arc-shaped groove portion 44a at the tip of the drive wire 18
4 is attached in a state of extending in the vertical direction.
In the conversion mechanism 19 configured as above, when the drive wire 18 reciprocates in the direction of arrow a, the sliding pin 42 is moved.
Slides in the vertical direction along the arc-shaped groove portion 44a, and accordingly, the substrate 40 swings about the rotation shaft 41.

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

The present invention can be applied to modifications and variations of the above embodiment without departing from the spirit of the present invention.

[0040]

As described above, according to the ultrasonic imaging catheter of the present invention, the reciprocating motion or rotary motion of the transmission wire is transferred to the outer tube portion via the conversion mechanism provided behind the vibrator. By converting into a swinging motion of a transducer having an opening larger than the diameter of the transducer, it is possible to scan the transducer in the direction of the larger opening, but the space for accommodating the conversion mechanism in the radial direction of the outer tube portion. Since it is not necessary, it is possible to provide an ultrasonic imaging catheter having a small observation diameter, a deep observation depth, and good image resolution.

[0041]

[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 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 modified example of the embodiment.

FIG. 6 is a diagram showing a second modified example 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 embodiment 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 the substrate.

FIG. 11 is a view showing the structure of the second embodiment of the conversion mechanism.

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

FIG. 13 is a view showing the structure of the fourth embodiment 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 conventional ultrasonic transducer driving mechanism.

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

[Explanation of symbols]

 10 Ultrasonic Imaging Catheter 12 Outer Tube 14 Ultrasonic Transducer 16 Rotating Axis 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)

[Claims] 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 in the vicinity of the tip 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 movement or a rotational movement of the transmission wire into a swinging movement of the transducer.