Catheter for diagnostic imaging

Abstract

This catheter for diagnostic imaging comprises a proximal outer tube, a proximal inner tube, an outer tube supporting tube, and a drive shaft, wherein: when the proximal inner tube is in a most advanced state of being pushed furthest into the proximal outer tube, a multiple-tube structure is formed in which the outer tube supporting tube, the proximal inner tube, and the proximal outer tube are positioned in this order outward in a radial direction from the drive shaft; when the proximal inner tube is in a most retracted state of being drawn furthest from the proximal outer tube, the rear end of the outer tube supporting tube is positioned in front of the front end of the proximal inner tube; the outer peripheral surface of a front end portion of the proximal inner tube has a diameter-enlarged portion with a rear end portion that functions as a stopper that comes into abutment with the proximal outer tube when the proximal inner tube is drawn from the proximal outer tube and reaches the most retracted state; the inner peripheral surface of the front end portion of the proximal inner tube has a guide surface that extends with a gradually decreasing diameter rearward from the front end surface of the proximal inner tube; and the guide surface is capable of guiding a rear end portion of the outer tube supporting tube when the proximal inner tube is pushed into the proximal outer tube from the most retracted state.

Description

Diagnostic imaging catheters

[0001] The present disclosure relates to diagnostic imaging catheters.

[0002] A diagnostic imaging catheter is known which has a proximal outer tube, a proximal inner tube, an outer tube support tube, and a drive shaft, and which forms a multi-tube structure in which, when the proximal inner tube is pushed all the way into the proximal outer tube, the outer tube support tube, the proximal inner tube, and the proximal outer tube are positioned in this order radially outward from the drive shaft (see, for example, Patent Document 1).

[0003] International Publication No. 2023 / 008539

[0004] In consideration of priming properties, the above-described diagnostic imaging catheter may be configured so that the rear end of the outer tube support tube is located forward of the front end of the proximal inner tube when the proximal inner tube is in the most retracted state, where it is pulled all the way out from the proximal outer tube. In this case, when the proximal inner tube is pushed into the proximal outer tube from the most retracted state, an external force may cause the rear end of the outer tube support tube to become eccentric with respect to the front end of the proximal inner tube, causing the rear end face of the outer tube support tube to come into contact with the front end face of the proximal inner tube, potentially preventing the catheter from being smoothly retracted inside the proximal inner tube.

[0005] Therefore, an object of the present disclosure is to provide a catheter for diagnostic imaging in which the rear end of the outer tube support tube is smoothly stored inside the proximal inner tube when the proximal inner tube is pushed into the proximal outer tube from the most retracted state.

[0006] One aspect of the present disclosure is as follows.

[0007] [1] A catheter for diagnostic imaging, comprising: a proximal outer tube, a proximal inner tube, an outer tube support tube, and a drive shaft; wherein, in a most advanced state in which the proximal inner tube is pushed all the way into the proximal outer tube, the outer tube support tube, the proximal inner tube, and the proximal outer tube form a multi-tube structure in which the outer tube support tube, the proximal inner tube, and the proximal outer tube are positioned radially outward from the drive shaft in this order; wherein, in a most retracted state in which the proximal inner tube is pulled all the way out from the proximal outer tube, the rear end of the outer tube support tube is positioned forward of the front end of the proximal inner tube; the outer peripheral surface of the front end of the proximal inner tube has an enlarged diameter portion having a rear end that serves as a stopper that abuts against the proximal outer tube when the proximal inner tube is pulled out from the proximal outer tube to reach the most retracted state; and the inner peripheral surface of the front end of the proximal inner tube has a guide surface that extends rearward while gradually reducing in diameter from the front end surface of the proximal inner tube, and the guide surface is capable of guiding the rear end of the outer tube support tube when the proximal inner tube is pushed into the proximal outer tube from the most retracted state.

[0008] [2] The diagnostic imaging catheter according to [1], wherein the outer diameter of the enlarged diameter section is constant from the front end to the rear end.

[0009] [3] A catheter for diagnostic imaging according to [1] or [2], which has an inner tube support tube, wherein in the most forward state, the inner tube support tube, the outer tube support tube, the proximal inner tube, and the proximal outer tube form the multi-tube structure, which are positioned in this order radially outward from the drive shaft, and wherein in the most retracted state, the front end of the inner tube support tube is positioned forward of the rear end of the outer tube support tube.

[0010] [4] A catheter for diagnostic imaging described in [3], wherein the telescopic mechanism, which is composed of the proximal outer tube, the proximal inner tube, the outer tube support tube, and the inner tube support tube, has an outer flow path formed between the proximal inner tube and the proximal outer tube and the inner tube support tube and the outer tube support tube in the most retracted state, and the outer flow path allows priming fluid to flow from the rear end of the telescopic mechanism to the front end of the telescopic mechanism in the most retracted state.

[0011] [5] A method for manufacturing a catheter for diagnostic imaging described in any one of [1] to [4], comprising a proximal inner tube forming step of using a mold having a guide surface forming surface shaped to follow the guide surface and an enlarged diameter portion forming surface shaped to follow the outer peripheral surface of the enlarged diameter portion, and bringing a molten front end portion of a tubular body, which is a preform of the proximal inner tube, into contact with the guide surface forming surface and the enlarged diameter portion forming surface to deform the molten front end portion, thereby forming the guide surface and the enlarged diameter portion.

[0012] [6] A method for manufacturing a catheter for diagnostic imaging described in [5], wherein the enlarged diameter portion molding surface has a constant diameter from the front end to the rear end, the outer diameter of the tubular body is smaller than the diameter of the enlarged diameter portion molding surface, and the diameter of the front end of the guide surface molding surface, which extends while gradually reducing in diameter toward the rear, is larger than the inner diameter of the front end of the tubular body.

[0013] According to the present disclosure, it is possible to provide a catheter for diagnostic imaging in which the rear end of the outer tube support tube is smoothly stored inside the inner tube at the proximal end when the inner tube at the proximal end is pushed into the outer tube at the proximal end from the most retracted state.

[0014] 5A is an external view showing a most advanced state of a diagnostic imaging catheter according to an embodiment of the present disclosure; FIG. 5B is an external view showing a most retracted state of the diagnostic imaging catheter of FIG. 1; FIG. 5C is a partially enlarged cross-sectional view of FIG. 1; FIG. 2 is a partially enlarged cross-sectional view of FIG. 2; FIG. 5D is a cross-sectional view showing a state when an end of a tubular body, which is a preformed product of a proximal inner tube, is brought into contact with a mold in order to manufacture the diagnostic imaging catheter of FIG. 1; FIG. 5E is a cross-sectional view showing a state when deformation of the end of the tubular body by the guide surface forming surface of the mold has begun, from the state of FIG. 5A; FIG. 5F is a cross-sectional view showing a state when deformation of the end of the tubular body by the guide surface forming surface and the enlarged diameter portion forming surface has been completed, from the state of FIG. 5C.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0016] 1 and 2 , a diagnostic imaging catheter 1 according to an embodiment of the present disclosure includes a sheath 2 to be inserted into a body cavity such as a blood vessel (such as a coronary artery) of a living body such as a patient, an extension / retraction mechanism 3 including a proximal outer tube 3a and a proximal inner tube 3b, and a drive shaft 4 having a signal transmitter / receiver 4a at its distal end, and while the sheath 2 is inserted into the body cavity, the extension / retraction mechanism 3 moves the drive shaft 4 toward the proximal end within the sheath 2, while the signal transmitter / receiver 4a generates a tomographic image of the area around the body cavity for diagnosis. The signal transmitter / receiver 4a may have an intravascular ultrasound (IVUS) structure, an optical coherence tomography (OCT) structure, or a structure including both.

[0017] The diagnostic imaging catheter 1 may be connected to an external device (not shown), and the external device may rotate the drive shaft 4 within the sheath 2 and pull the proximal inner tube 3b toward the proximal end while controlling transmission and reception of signals from the signal transmitter / receiver 4a to and from the periphery of the body cavity to generate a tomographic image. The distal end of the sheath 2 may have a guidewire insertion member 2a through which a guidewire (not shown) passes.

[0018] The telescopic mechanism 3 moves the drive shaft 4 toward the proximal end within the sheath 2 when the proximal inner tube 3b is pulled toward the proximal end relative to the proximal outer tube 3a and extends.

[0019] More specifically, as shown in FIGS. 1 to 4, the diagnostic imaging catheter 1 has a proximal outer tube 3a, a proximal inner tube 3b, an outer tube support tube 3c, and a drive shaft 4. In a most advanced state (see FIGS. 1 and 3) in which the proximal inner tube 3b is pushed all the way into the proximal outer tube 3a, the outer tube support tube 3c, the proximal inner tube 3b, and the proximal outer tube 3a form a multi-tube structure in which the outer tube support tube 3c, the proximal inner tube 3b, and the proximal outer tube 3a are positioned in this order radially outward from the drive shaft 4. In a most retracted state (see FIGS. 2 and 4) in which the proximal inner tube 3b is pulled all the way out from the proximal outer tube 3a, the outer tube support tube 3c forms a multi-tube structure. The rear end of the outer tube support tube 3c is located forward of the front end of the handheld inner tube 3b, and the outer surface of the front end of the handheld inner tube 3b has an expanded diameter portion 3b1 with a rear end that serves as a stopper 3b2 that abuts against the handheld outer tube 3a when the handheld inner tube 3b is pulled out of the handheld outer tube 3a to reach its most retracted state, and the inner surface of the front end of the handheld inner tube 3b has a guide surface 3b3 that extends from the front end surface of the handheld inner tube 3b toward the rear while gradually reducing in diameter, and the guide surface 3b3 can guide the rear end of the outer tube support tube 3c when the handheld inner tube 3b is pushed into the handheld outer tube 3a from its most retracted state.

[0020] In this embodiment, the front-to-rear direction is the direction along the central axis O of the inner tube 3b at hand, the front side is the tip side (patient side) of the diagnostic imaging catheter 1, and the rear side is the base side (practitioner side), the radial direction is the direction perpendicular to the central axis O, and the circumferential direction is the direction circumferential around the central axis O.

[0021] According to the above configuration, the inner diameter of the front end of the proximal inner tube 3b can be increased by the amount of the guide surface 3b3, thereby preventing the rear end surface of the outer tube support tube 3c from abutting against the front end surface of the proximal inner tube 3b when the proximal inner tube 3b is pushed from the most retracted state into the proximal outer tube 3a. Furthermore, the guide surface 3b3, which extends from the front end surface of the proximal inner tube 3b while gradually reducing in diameter toward the rear, guides the rear end of the outer tube support tube 3c toward the inside (radially inward and rearward) of the proximal inner tube 3b. Therefore, a diagnostic imaging catheter 1 can be realized in which the rear end of the outer tube support tube 3c is smoothly housed inside the proximal inner tube 3b when the proximal inner tube 3b is pushed from the most retracted state into the proximal outer tube 3a. In this embodiment, the guide surface 3b3 extends rearward while gradually reducing in diameter in a straight line. However, the configuration is not limited to this. For example, the guide surface 3b3 may extend rearward while gradually reducing in diameter in a bent line, curved line, or stepped shape.

[0022] In this embodiment, as described above, the telescopic mechanism 3 is provided in a direction in which the proximal inner tube 3b is pulled toward the proximal end relative to the proximal outer tube 3a, but it may also be configured in the opposite direction. In this case, the telescopic mechanism 3 is configured to move the drive shaft 4 toward the proximal end within the sheath 2 when the proximal outer tube 3a is pulled toward the proximal end relative to the proximal inner tube 3b and extended, with the front side being the proximal end and the rear side being the distal end.

[0023] The outer diameter of the enlarged diameter portion 3b1 is constant from the front end to the rear end. Here, "constant" means that the outer diameter is constant to the extent that a slight inclination due to the draft angle normally set in a molding die when forming the stopper 3b1 is tolerated. This configuration makes it easy to ensure the strength of the stopper 3b2 (the rear end of the enlarged diameter portion 3b1).

[0024] The diagnostic imaging catheter 1 has an inner tube support tube 3d, and in the most advanced state, the inner tube support tube 3d, outer tube support tube 3c, proximal inner tube 3b, and proximal outer tube 3a form a multi-tube structure positioned in this order radially outward from the drive shaft 4, and in the most retracted state, the front end of the inner tube support tube 3d is positioned forward of the rear end of the outer tube support tube 3c. With this configuration, when the proximal inner tube 3b is pushed into the proximal outer tube 3a from the most retracted state, the inner tube support tube 3d can prevent the rear end of the outer tube support tube 3c from becoming eccentric relative to the front end of the proximal inner tube 3b due to an external force. This makes it easier to smoothly store the rear end of the outer tube support tube 3c inside the proximal inner tube 3b.

[0025] The dimensions and inclination angle θ of the guide surface 3b3 of the hand-held inner tube 3b can be set as appropriate, but it is preferable that the diameter at the front end of the guide surface 3b3 be 1.75 mm or more, the length of the guide surface 3b3 in the front-to-rear direction be 1.8 mm or more, and the inclination angle θ with respect to the central axis O be 9° or more.

[0026] In this embodiment, the front end of the hand-held inner tube 3b has a front end face extending radially outward from the front end of the guide surface 3b3, and the front end face extends in a straight line in the radial direction, but this is not limited to this. For example, the front end face may extend in a curved line, or the front end of the guide surface 3b3 may be directly connected to the front end of the expanded diameter portion 3b1 without providing a front end face.

[0027] The rear end of the inner circumferential surface of the proximal outer tube 3a has a stepped surface 3a1 that narrows in diameter in a step-like manner and faces forward, and when the proximal inner tube 3b reaches its most retracted state, a stopper 3b2 abuts against the stepped surface 3a1, causing the proximal outer tube 3a to stop. The proximal outer tube 3a has a cylindrical proximal outer tube main body 3a2 and a unit connector 3a3 that is connected to the rear end of the proximal outer tube main body 3a2, and the unit connector 3a3 has the stepped surface 3a1 against which the stopper 3b2 abuts.

[0028] The telescopic mechanism 3 has an outer flow path 3e formed between the proximal inner tube 3b and the proximal outer tube 3a and the inner tube support tube 3d and the outer tube support tube 3c in the most retracted state, and the outer flow path 3e allows a priming liquid such as physiological saline to flow from the rear end of the telescopic mechanism 3 to the front end of the telescopic mechanism 3 in the most retracted state. Furthermore, because the rear end of the outer tube support tube 3c is located further forward than the front end of the proximal inner tube 3b in the most retracted state of the telescopic mechanism 3, a wide flow path cross-sectional area can be ensured for the outer flow path 3e within the proximal inner tube 3b when priming in the most retracted state, enabling smooth priming (see the white arrow in Figure 4).

[0029] If the drive shaft 4 buckles within the telescopic mechanism 3 when moving from the most retracted position to the most advanced position after priming, there is a risk that the drive shaft 4 may be damaged, such as twisted, when rotated in a buckled state. The provision of the inner tube support tube 3d and the outer tube support tube 3c can prevent such buckling from occurring.

[0030] The telescopic mechanism 3 has an inner flow path 3f formed radially inside the inner tube support tube 3d and the outer tube support tube 3c when in the most retracted state, and the inner flow path 3f can flow priming liquid from the rear end of the telescopic mechanism 3 to the front end of the telescopic mechanism 3 when in the most retracted state.

[0031] The telescopic mechanism 3 has an outer tube spacer 3g that is located between the proximal outer tube 3a and the outer tube support tube 3c and holds the outer tube support tube 3c, and the outer surface of the outer tube spacer 3g contacts the inner surface of the front end of the proximal outer tube 3a and the inner surface contacts the outer surface of the front end of the outer tube support tube 3c, and the outer tube spacer 3g forms an outer tube connecting flow path (not shown) that connects the outer flow path 3e and the inner flow path 3f.

[0032] The telescopic mechanism 3 has an inner pipe spacer 3h that is located between the proximal inner pipe 3b and the inner pipe support tube 3d and holds the inner pipe support tube 3d, and the inner pipe spacer 3h has an outer surface that contacts the inner surface of the rear end of the proximal inner pipe 3b and an inner surface that contacts the outer surface of the rear end of the inner pipe support tube 3d, and the inner pipe spacer 3h forms an inner pipe connecting flow path (not shown) that connects the outer flow path 3e and the inner flow path 3f.

[0033] The diagnostic imaging catheter 1 has a relay connector 5 that connects the sheath 2 to the distal end of the extension / retraction mechanism 3 (the distal end of the proximal outer tube 3a), and a hub 6 that is connected to the proximal end of the extension / retraction mechanism 3 (the proximal end of the proximal inner tube 3b), and the hub 6 has a port 6a to which an injection device (not shown) for a priming solution is connected, and an internal flow path 6b that connects a flow path within the injection device connected to the port 6a to the inner flow path 3f and outer flow path 3e of the extension / retraction mechanism 3. The drive shaft 4 extends through the internal flow path 6b of the hub 6, and has a connection part (not shown) for connecting to an external device at its proximal end.

[0034] Priming is performed by injecting priming liquid from port 6a using an injection device, flowing it through the internal flow path 6b of the hub 6, the inner flow path 3f and outer flow path 3e of the telescopic mechanism 3, and the flow path within the sheath 2 in that order, and then discharging it from the tip opening (not shown) of the sheath 2.

[0035] 5A to 5D, the diagnostic imaging catheter 1 may be manufactured by a method for manufacturing a diagnostic imaging catheter, which includes a proximal inner tube 3b forming step in which a mold 7 having a guide surface-forming surface 7a1 shaped to conform to the guide surface 3b3 and an enlarged-diameter portion-forming surface 7b shaped to conform to the outer peripheral surface of the enlarged-diameter portion 3b1 is used, and the molten front end of a tubular body 8, which is a preform of the proximal inner tube 3b, is brought into contact with the guide surface-forming surface 7a1 and the enlarged-diameter portion-forming surface 7b to deform the front end, thereby forming the guide surface 3b3 and the enlarged-diameter portion 3b1. With this configuration, the guide surface 3b3 and the enlarged-diameter portion 3b1 of the proximal inner tube 3b can be formed simultaneously, thereby achieving efficient manufacturing.

[0036] The enlarged-diameter-portion-forming surface 7b has a constant diameter from the front end to the rear end, the outer diameter of the tube 8 is smaller than the diameter of the enlarged-diameter-portion-forming surface 7b, and the diameter of the front end of the guide surface-forming surface 7a1, which extends while gradually reducing in diameter toward the rear, is larger than the inner diameter of the front end of the tube 8. According to the above configuration, by advancing the tube 8 relative to the mold 7 by an external force as shown by the white arrows in Figures 5A to 5D, the front end of the tube 8 is pressed against the guide surface-forming surface 7a1, causing it to undergo enlarged deformation and come into close contact with the enlarged-diameter-portion-forming surface 7b, thereby simultaneously forming the guide surface 3b3 and the enlarged-diameter portion 3b1 of the proximal inner tube 3b. In this embodiment, a front-end surface-forming surface 7c shaped to fit along the front end surface of the proximal inner tube 3b is provided between the front end of the guide surface-forming surface 7a1 and the front end of the enlarged-diameter-portion-forming surface 7b. However, the present invention is not limited to this, and the shape or presence or absence of the front end surface-forming surface 7c can be appropriately determined depending on the shape or presence or absence of the front end surface of the proximal inner tube 3b.

[0037] The external force is not particularly limited and may be, for example, mechanical power or gravity. To advance the tube 8 relative to the die 7, the external force may be applied only to the die 7, only to the tube 8, or to both. The die 7 is not limited to a configuration having the guide surface molding surface 7a1 and the enlarged diameter portion molding surface 7b integrally as shown in the figure, and may be configured, for example, such that the guide surface molding surface 7a1 and the enlarged diameter portion molding surface 7b have movable parts that allow them to move relative to each other during the process of forming the proximal inner tube 3b, although this is not shown.

[0038] The mold 7 has a protrusion 7a having a guide surface molding surface 7a1 on its outer circumferential surface, and the protrusion 7a has an insertion portion 7a2 located rearward of the guide surface molding surface 7a1, and the outer circumferential surface of the insertion portion 7a2 extends rearward while gradually reducing in diameter from the rear end of the guide surface molding surface 7a1. According to the above configuration, even if the tube 8 becomes eccentric with respect to the guide surface molding surface 7a1 when the tube 8 is advanced relative to the mold 7 in the proximal inner tube 3b forming step, the inner circumferential surface of the front end of the tube 8 can be guided to the guide surface molding surface 7a1 by the insertion portion 7a2, thereby achieving stable production.

[0039] In the process of forming the inner tube 3b, the front end of the tube 8 is heated through the heated mold 7 to be in a molten state. With the above configuration, the front end of the tube 8 can be melted and deformed by contact with the mold 7, thereby achieving further efficiency in manufacturing. There are no particular restrictions on the method of heating the mold 7, and high-frequency induction heating, for example, can be used. Note that in the process of forming the inner tube 3b, the tube 8 may be heated directly without using the mold 7.

[0040] The protrusion 7a may have a hole 7a3 extending forward from the rear end of the protrusion 7a, and the method for manufacturing a diagnostic imaging catheter may be configured such that, in the step of forming the proximal inner tube 3b, the linear member 9 is inserted into the hole 7a3 of the protrusion 7a and the tubular body 8, and the tubular body 8 is advanced relative to the mold 7 until it contacts the protrusion 7a. This configuration makes it easy to accurately guide the tubular body 8 relative to the mold 7 until it contacts the protrusion 7a in the step of forming the proximal inner tube 3b. The hole 7a3 of the protrusion 7a may be configured as a through hole or a blind hole.

[0041] The method for manufacturing a diagnostic imaging catheter may be configured such that, in the proximal inner tube 3b forming step, with the linear member 9 inserted into the hole 7a3 of the convex portion 7a and the tubular body 8, the tubular body 8 is advanced relative to the mold 7 from the time of contact with the convex portion 7a until the guide surface 3b3 and the expanded diameter portion 3b1 can be formed. With this configuration, in the proximal inner tube 3b forming step, it is possible to easily and accurately guide the tubular body 8 relative to the mold 7 from the time of contact with the convex portion 7a until the guide surface 3b3 and the expanded diameter portion 3b1 can be formed.

[0042] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present disclosure.

[0043] REFERENCE SIGNS LIST 1 Diagnostic imaging catheter 2 Sheath 2a Guide wire insertion member 3 Telescopic mechanism 3a Proximal outer tube 3a1 Step surface 3a2 Proximal outer tube main body 3a3 Unit connector 3b Proximal inner tube 3b1 Expanded diameter portion 3b2 Stopper 3b3 Guide surface 3c Outer tube support tube 3d Inner tube support tube 3e Outer flow path 3f Inner flow path 3g Outer tube spacer 3h Inner tube spacer 4 Drive shaft 4a Signal transmitting / receiving unit 5 Relay connector 6 Hub 6a Port 6b Internal flow path 7 Mold 7a Convex portion 7a1 Guide surface forming surface 7a2 Insertion portion 7a3 Hole 7b Expanded diameter portion forming surface 7c Front end surface forming surface 8 Tubular body 9 Linear member O Central axis θ Inclination angle

Claims

1. A catheter for diagnostic imaging, comprising: a proximal outer tube, a proximal inner tube, an outer tube support tube, and a drive shaft; wherein in a most advanced state in which the proximal inner tube is pushed all the way into the proximal outer tube, the outer tube support tube, the proximal inner tube, and the proximal outer tube are positioned in this order radially outward from the drive shaft to form a multi-tube structure; wherein in a most retracted state in which the proximal inner tube is pulled all the way out from the proximal outer tube, the rear end of the outer tube support tube is positioned forward of the front end of the proximal inner tube; the outer peripheral surface of the front end of the proximal inner tube has an enlarged diameter portion having a rear end serving as a stopper that abuts against the proximal outer tube when the proximal inner tube is pulled out of the proximal outer tube to reach the most retracted state; and wherein the inner peripheral surface of the front end of the proximal inner tube has a guide surface that extends rearward while gradually reducing in diameter from the front end surface of the proximal inner tube, and wherein the guide surface is capable of guiding the rear end of the outer tube support tube when the proximal inner tube is pushed into the proximal outer tube from the most retracted state.

2. The diagnostic imaging catheter according to claim 1, wherein the outer diameter of said enlarged portion is constant from the front end to the rear end.

3. A catheter for diagnostic imaging as described in claim 1, which has an inner tube support tube, and in the most forward state, the inner tube support tube, the outer tube support tube, the proximal inner tube and the proximal outer tube form a multi-tube structure positioned in this order radially outward from the drive shaft, and in the most retracted state, the front end of the inner tube support tube is positioned forward of the rear end of the outer tube support tube.

4. A catheter for diagnostic imaging as described in claim 3, wherein an extension mechanism composed of the outer tube at hand, the inner tube at hand, the outer tube support tube and the inner tube support tube has an outer flow path formed between the inner tube at hand and the outer tube at hand and the inner tube support tube and the outer tube support tube in the most retracted state, and the outer flow path is capable of flowing priming fluid from the rear end of the extension mechanism to the front end of the extension mechanism in the most retracted state.

5. A method for manufacturing a catheter for diagnostic imaging according to any one of claims 1 to 4, comprising a proximal inner tube forming step of using a mold having a guide surface forming surface shaped to conform to the guide surface and an enlarged portion forming surface shaped to conform to the outer circumferential surface of the enlarged portion, and bringing a molten front end portion of a tubular body, which is a preform of the proximal inner tube, into contact with the guide surface forming surface and the enlarged portion forming surface to deform the front end portion, thereby forming the guide surface and the enlarged portion.

6. A method for manufacturing a catheter for diagnostic imaging as described in claim 5, wherein the enlarged diameter portion molding surface has a constant diameter from the front end to the rear end, the outer diameter of the tubular body is smaller than the diameter of the enlarged diameter portion molding surface, and the diameter of the front end of the guide surface molding surface, which extends while gradually narrowing toward the rear, is larger than the inner diameter of the front end of the tubular body.

Images