Patent Description:
In particular, the present invention relates to an optical imaging apparatus according to the preamble of claim <NUM>, such as it is, e.g., known from <CIT>.

There are known, as apparatuses for acquiring an image of a vascular lumen, an optical coherence tomography (OCT: Optical Coherence Tomography) apparatus, etc. Furthermore, as an improved version of the OCT apparatus, the development of a swept-source OCT (SS-OCT) apparatus using wavelength sweep is underway (Patent Literature <NUM>). These are generically referred to as "imaging apparatuses for diagnoses", hereinafter.

The imaging apparatus for diagnosis employs a catheter accommodating an imaging core that transmits and receives light in a tip end portion thereof so as to be rotatable and axially movable. The imaging core is connected to a drive shaft having generally the same length as an overall length of the catheter. Furthermore, the drive shaft accommodates therein an optical fiber. Moreover, a connector to connect the catheter to an MDU (motor drive unit) part included in the imaging apparatus for diagnosis is provided on a rear end of the catheter. The MDU part is a drive unit, which functions as a power source for the rotation and axial movement of the drive shaft, and has a connector to connect the MDU part to the catheter.

The connection between the MDU part and the catheter will now be considered in more detail.

Reference symbol 2A of <FIG> illustrates a manner in which a catheter connector section (hereinafter, catheter connector) <NUM> is moved in the direction of an arrow <NUM> and connected to a connector section (hereinafter, MDU connector) <NUM> of the MDU part <NUM>. Reference symbol 2B of <FIG> is a front view of the MDU connector <NUM>. Reference symbol 2C of <FIG> is a partially transparent perspective view of a knob engagement portion <NUM> which is located at the center of the MDU connector <NUM>, into which a knob of the catheter is fitted, and which supports the knob thereof. Reference symbol 2D of <FIG> is a planar development view illustrating an inner surface of the knob engagement section <NUM> shown in FIG. 2C when the knob engagement portion <NUM> is taken along line A-A'. Furthermore, <FIG> illustrates a cross-sectional structure of an ordinary catheter connector <NUM>.

The MDU part <NUM> is roughly composed by a base section <NUM> and a slider section <NUM> which is slidable with respect to the base section <NUM> along an arrow <NUM> shown in <FIG>. The base section <NUM> is provided with various operation switches including a grip section <NUM> for gripping a catheter sheath <NUM>. Furthermore, the base section <NUM> has therein a circuit board and a motor for allowing the slider section <NUM> to slide along the arrow <NUM>. The slider section <NUM> is provided with the MDU connector <NUM> accommodating the catheter connector <NUM> and connected thereto, and has therein a motor for rotating the drive shaft within the catheter and a structure for optically connecting the optical fiber of the drive shaft to an optical fiber within a cable <NUM>. The MDU connector <NUM> functions as a cover protecting a connection state when the catheter connector <NUM> is connected to the MDU connector <NUM>.

As indicated by reference symbol 2B of <FIG>, the MDU connector <NUM> has therein a connector engagement portions <NUM> which has guide grooves 205a and 205b for guiding projection portions <NUM> and <NUM> which the catheter connector <NUM> has. When the projection portions <NUM> and <NUM> of the catheter connector <NUM> are fitted into the MDU connector <NUM> along these guide grooves 205a and 205b, the catheter and the MDU part <NUM> are mechanically integrated with each other. It is noted that the connector engagement portion <NUM> does not rotate but is fixed.

Furthermore, when a knob <NUM> (see <FIG>) holding the optical fiber located at a central position of the catheter connector <NUM> is fitted into the knob engagement portion <NUM>, the knob engagement portion <NUM> is optically connected to the optical fiber within the catheter and rotates integrally with the knob <NUM>. Guide walls <NUM> for guiding a projection portion <NUM> provided on a tip end of the knob <NUM> are provided inside of the knob engagement portion <NUM>. As indicated by reference symbol 2C of <FIG>, the guide walls <NUM> correspond to ridgelines of a mountain within the knob engagement portion <NUM>. It is reference symbol 2D of <FIG> that a planar development view which illustrates the inner surface of the knob engagement portion <NUM> taken along line A-A' in the perpendicular direction passing through a peak of the "mountain" defined by the guide walls <NUM>. As clear from 2D of <FIG>, a space sandwiched between the guide wall <NUM> forms a guide groove <NUM>. A width WO of the guide groove <NUM> near an opening side of the knob engagement portion <NUM> is substantially equal to an inner circumference of the knob engagement portion <NUM>, the width WO changes to a width W1 along the depth direction, and the width in a state where the knob <NUM> has been fitted into the knob engagement portion <NUM> to some extent becomes equal to a width of the projection portion <NUM>, thereby guiding the knob <NUM> linearly. Moreover, an inclination angle of the guide walls <NUM> is not limited to a specific angle but is preferably <NUM> degrees to <NUM> degrees, more preferably <NUM> degrees to <NUM> degrees. As this inclination angle is greater, phase shift correction becomes possible. On the other hand, as the inclination angle is greater, a stroke (length in the depth direction) necessary to attach the catheter connector <NUM> becomes larger, so that an appropriate angle is determined as the inclination angle in the light of design. It is noted that the inclination angle of <NUM> degrees is adopted.

As shown in <FIG>, the catheter connector <NUM> supports a catheter sheath <NUM> and has an opening portion <NUM> for connecting the catheter connector <NUM> to the MDU part <NUM>. The catheter connector <NUM> has therein the knob <NUM> which is rotatable integrally with a drive shaft <NUM> accommodated in the catheter sheath <NUM>. This knob <NUM> is constituted by PBT (Poly Butylene Terephthalate), and forms a structure for guiding an optical fiber <NUM> accommodated in the drive shaft and exposing a tip end portion of the optical fiber <NUM>. It is noted that a support section <NUM> prevents the knob <NUM> from projecting outside and applies a force to the knob <NUM> in the direction of cancelling the fitting of the optical connector to the knob <NUM> when the catheter connector <NUM> is pulled out from the MDU part <NUM>.

As shown, a surface of an end portion of the optical fiber <NUM> is not a surface orthogonal to the axial direction thereof but is a slope inclined at an angle θ with respect to the orthogonal surface. On the other hand, an end surface (not shown) of an optical fiber located deep in the knob engagement portion <NUM> within the MDU part <NUM> has the same inclination angle, the optical fiber is exposed, and the end surfaces of the two optical fibers are surface-connected to each other. The reason for setting the inclination angle θ to each fiber end surface is to mitigate the influence of reflected light on a connection surface therebetween.

As such, when the catheter connector <NUM> is attached to the MDU part <NUM>, the respective fiber end surfaces are surface-connected to each other. To be more exact, it is necessary to connect the catheter connector <NUM> to the MDU part <NUM> without causing phase shift in the rotational direction. For this reason, the knob <NUM> has the projection portion (key) <NUM> for defining an angle of the knob in the rotational direction thereof within the catheter connector <NUM>. On the other hand, the knob engagement portion <NUM> of the MDU part <NUM> side is provided with the guide groove <NUM> defined by the aforementioned guide walls <NUM> so that the knob <NUM> and the knob engagement portion <NUM> are fixed to each other at a determined angle. Namely, when a user holds the catheter connector <NUM> and inserts the projection portions <NUM> and <NUM> of the catheter connector into the connector engagement portion <NUM> of the MDU connector <NUM> along the guide grooves 205a and 205b, the projection portion <NUM> of the knob <NUM> collides against the guide walls <NUM> of the knob engagement portion <NUM>, and when the user subsequently and continuously presses the catheter connector <NUM> into the connector engagement portion <NUM>, the knob engagement portion <NUM> rotates and the projection portion <NUM> of the knob <NUM> is finally guided along the guide groove <NUM> of the knob engagement portion <NUM>, thereby surface-connecting the end surfaces of the optical fibers of the catheter connector <NUM> and the MDU part <NUM> to each other.

As described above, the user performs the operation for holding the catheter connector <NUM> in user's hand and pressing the catheter connector <NUM> into the connector section <NUM> of the MUD part <NUM>. At this time, positions of the projection portions <NUM> and <NUM> of the catheter connector <NUM> are defined in the MDU part <NUM> side. On the other hand, the knob <NUM> receives a force for connecting the catheter connector <NUM> to the MDU part <NUM> via an elastic body <NUM> in the catheter insertion direction and is connected to the knob engagement portion <NUM>. At this time, because of many members associated with the connection, it is considered that the knob <NUM> collides against the knob engagement portion <NUM> and the connection cannot be completed, depending on a variation in tolerance. In that case, providing the elastic body <NUM> that tends to relatively deform in an end portion of the knob <NUM> makes it possible to mitigate dimensional inconsistency during the connection. It is noted that it is necessary for a reaction force when the elastic body <NUM> deforms to exceed a load necessary for completing the connection between the knob <NUM> and the knob engagement portion <NUM>; thus, the elastic body <NUM> has a spring constant equal to or higher than a certain value. A support section <NUM> is provided to fixedly support the elastic body <NUM>.

Providing the abovementioned structure enables the optical fibers to be appropriately connected to each other when the catheter is connected to the MDU part <NUM>. It is noted that silicone rubber is normally used for this elastic body <NUM>. Furthermore, when the connection between the catheter connector <NUM> and the MDU connector <NUM> is completed both mechanically and optically, the knob <NUM> is integrated with the knob engagement portion <NUM>. The projection portions <NUM> and <NUM> are similarly fixedly supported in the MDU part <NUM>. As a result, a sufficient space is created between a rear end surface 301a of the knob <NUM> and a surface 311a of the elastic body <NUM>.

As described above, when the user performs the operation for connecting the catheter to the MDU part <NUM>, the projection portion <NUM> of the knob <NUM> abuts the guide walls of the knob engagement portion <NUM> of the MDU part <NUM>. When the user subsequently and continuously performs the operation for pressing the catheter connector <NUM> into the MDU connector <NUM>, the rear end surface 301a of the knob <NUM> abuts the surface 311a of the elastic body <NUM> and a frictional force is generated therebetween. Namely, the knob <NUM> is suppressed from rotating.

A configuration related to rotation drive within the MDU part <NUM> is connected to the knob engagement portion <NUM> of the MDU part <NUM>; therefore, a force for suppressing the rotation (hereinafter, a rotation suppression force for the knob engagement portion <NUM>) acts on the knob engagement portion <NUM> even in a non-driven state although the knob engagement portion <NUM> is rotatable. Therefore, when the user continues the operation for inserting the catheter connector <NUM> in a state where the rear end surface 301a of the knob <NUM> abuts the surface 311a of the elastic body <NUM>, a considerable load is applied to a contact position between the projection portion <NUM> of the knob <NUM> and the guide walls <NUM> of the knob engagement portion <NUM>, and the projection portion <NUM> of the knob <NUM> is broken according to circumstances. On the other hand, because the knob engagement portion <NUM> of the MDU part <NUM> is supposed to be used a plurality of times and a resin having sufficiently high hardness is used therefor, the probability of breaking the knob engagement portion <NUM> is low but yet the probability of flawing a collision position is not zero. Once there occurs a flaw in the position, the knob engagement portion <NUM> moves jerkily in the position and loses a smooth guiding function, with the result that the connector of the MDU part <NUM> might be broken according to circumstances.

The present invention has been made in the light of the abovementioned problems and an object of the present invention is to provide a technique for alleviating not only a burden on a catheter but also a burden on an MDU part and for yet enabling the long-term use of the MDU part.

To solve the abovementioned problems, an optical imaging apparatus for diagnosis of the present invention has the configuration according to claim <NUM>. Preferred embodiments are presented in the dependent claims.

According to the present invention, it is possible to alleviate not only a burden on the catheter but also a burden on the MDU part and to yet ensure the long-term use of the MDU part with a simple structure.

Other features and advantages of the present invention will become clearer from the disclosure given below with reference to the accompanying drawings. It is noted that same or like configurations are denoted by the same reference symbols in the accompanying drawings.

The accompanying drawings are encompassed in the specification, constitute part of the specification, illustrate embodiments of the present invention, and are used for describing the principle of the present invention together with the disclosure.

Embodiments according to the present invention will be described in detail hereinafter with reference to the accompanying drawings.

<FIG> illustrates an example of an overall configuration of an optical tomography apparatus for diagnosis (hereinafter, simply imaging apparatus for diagnosis) <NUM> according to an embodiment of the present invention. An apparatus using a wavelength swept light source is taken by way of example in the embodiment; however, since the present invention is applicable to any apparatus using a single wavelength light source, it would be appreciated that the use of the wavelength swept light source is given only for illustrated purposes.

The imaging apparatus for diagnosis <NUM> is composed by a catheter <NUM>, an MDU part <NUM>, and an operation control apparatus <NUM>, and the MDU part <NUM> and the operation control apparatus <NUM> are connected to each other by a cable <NUM> via a connector <NUM>. This cable <NUM> accommodates therein an optical fiber and various signal lines.

The catheter <NUM> protects the optical fiber and accommodates therein a drive shaft for transmitting a rotational force. An imaging core, which has a light transmission-reception unit for transmitting light (measurement light) transmitted from the operation control apparatus <NUM> via the MDU part <NUM> in the direction generally orthogonal to a central axis of the optical fiber and receiving reflected light from an outside for the transmitted light, is provided on a tip end of this optical fiber.

The MDU part <NUM> has the structure of <FIG> previously described. Briefly, the MDU part <NUM> holds the catheter <NUM> via a connector provided on a rear end of the catheter. The drive shaft within the catheter is rotated by driving a motor included in the MDU part <NUM>, thereby making rotatable the imaging core provided on the tip end thereof. Furthermore, the MDU part <NUM> performs processing for pulling (retreating) the drive shaft within the catheter at a predetermined speed by driving a motor provided in a linear drive unit included therein.

With the abovementioned configuration, the catheter <NUM> is guided into a patient's blood vessel, and a radial scan motor included in the MDU part <NUM> is driven to rotate the drive shaft within the catheter <NUM>, thereby making it possible to scan a vascular luminal surface over <NUM> degrees. Moreover, the MDU part <NUM> pulls the drive shaft within the catheter <NUM> at the predetermined speed, thereby performing a scan along an axis of the blood vessel. It is thereby possible to obtain a plurality of tomographic images viewed from within the blood vessel along the axis of the blood vessel and also possible to reconstruct a three-dimensional blood vessel image by connecting those images.

The operation control apparatus <NUM> has a function to exert an overall control over operation performed by the imaging apparatus for diagnosis <NUM>. The operation control apparatus <NUM> has, for example, a function to input various set values based on user's (doctor's) instructions, and a function to process data obtained by measurement and display the processed data as tomographic images of an interior of a body cavity.

The operation control apparatus <NUM> is provided with a main body control unit <NUM>, a printer/DVD recorder <NUM>-<NUM>, an operation panel <NUM>, an LCD monitor <NUM>, etc. The main body control unit <NUM> generates an optical tomographic image. The optical tomographic image is generated by generating data on interference light by interfering the reflected light which has been obtained by the measurement with reference light which has been obtained by separating light from the light source and by processing line data which has been generated on the basis of the interference light.

The printer/DVD recorder <NUM>-<NUM> prints out a processing result of the main body control unit <NUM> and/or stores the processing result as data. The operation panel <NUM> is a user interface to which a user inputs various set values and instructions. The LCD monitor <NUM>, which functions as a display apparatus, displays, for example, the tomographic image generated by the main body control unit <NUM>. <NUM> denotes a mouse that serves as a pointing device (coordinate input device).

While the general configuration and operation of the imaging apparatus for diagnosis <NUM> have been described above, the feature of the present embodiment lies in the structure of the connector of the catheter <NUM> to be connected to the MDU part <NUM>. A structure of the MDU part <NUM> is assumed to be the same as that shown in <FIG>, and the structure of the catheter connector <NUM> according to the embodiment will now be described with reference to <FIG>. It is noted that similar parts to those of the conventional connector shown in <FIG> are denoted by the same reference symbols and the reference symbols are not described herein.

<FIG> illustrates a cross-sectional structural view of the catheter connector <NUM> according to the embodiment. The catheter connector <NUM> differs from that shown in <FIG> in that a hard ring member <NUM> is interposed between the elastic body <NUM> (constituted by silicone rubber) and the knob <NUM> and are the same in the other respects. This ring member <NUM> has a cylindrical portion fitted into an inside diameter of the elastic body <NUM>, and a flange portion (see <FIG>) for dispersing a force of contact when the ring member <NUM> contacts the rear end surface 301a of the knob <NUM>. Furthermore, a projection portion 401a along a circumference of the flange portion is provided on a knob <NUM>-side thereof, as shown in <FIG>. A diameter R of this projection portion 401a is set to be equal to or close to an innermost diameter of the flange portion. It is noted that a depth L0 of the cylindrical portion of the ring member <NUM> is sufficiently smaller than a thickness L of the elastic body <NUM> in the depth direction thereof. Structuring the catheter connector <NUM> as described above makes it possible to maintain buffering properties by the elastic body <NUM> even when the knob <NUM> retreats and the rear end surface 301a of the knob is pressure-contacted to the projection portion 401a of the ring member <NUM> if the catheter is to be connected to the MDU part <NUM>.

Moreover, POM (Polyoxymethylene) is used as a material of this ring member <NUM> according to the embodiment. As a result, the material of the ring member <NUM> can reduce per se a frictional force between the knob <NUM> and the elastic body <NUM>. Furthermore, providing the projection portion 401a along the innermost diameter of the ring member <NUM> makes it possible to further reduce a frictional torque between the elastic body <NUM> and the knob <NUM>. As a result, a frictional torque between the ring member <NUM> and the knob <NUM> can be made sufficiently lower than a rotation suppression force of the knob engagement portion <NUM> when the MDU part <NUM> is not driven. Namely, when the catheter connector <NUM> is inserted into the MDU connector <NUM>, it is the knob <NUM>-side of the catheter connector <NUM> that rotates, so that it is possible to greatly alleviate a burden on a contact point between the projection portion <NUM> of the knob <NUM> and the guide walls <NUM> of the knob engagement portion <NUM> as compared with a conventional technique.

It is noted that the example where the POM is used as the material of the ring member <NUM> according to the embodiment has been described; in conclusion, however, the material of the ring member is not limited to the POM as long as the material thereof satisfies a condition that the frictional force between the ring member <NUM> and the knob <NUM> is lower than the rotation suppression force of the knob engagement portion <NUM> when the MDU part <NUM> is not driven. Nevertheless, PBT (Poly Butylene Terephthalate resin) is generally used for the knob <NUM> and the POM is preferably used for the material of the ring member <NUM> since the POM is sufficiently lower in frictional resistance than the PBT and is inexpensive.

As described so far, the catheter according to the present embodiment can be configured so that the side thereof which operates to rotate for ensuring accurate optical coupling is the knob side thereof within the catheter which is low in resistance during rotation when the catheter is connected to the MDU part which the imaging apparatus for diagnosis has. It is, therefore, possible to alleviate the burden on the MDU part <NUM> during the connection as compared with a conventional structure and improve a working ratio thereof.

Furthermore, the inventor of the present invention paid attention to the generation of a rotational torque about the contact point as indicated by an arrow <NUM> of <FIG> from a deviation between a line of force generated at the contact point and a line of force of a resultant force received by the knob <NUM> from the ring member <NUM> when the projection portion <NUM> of the knob <NUM> abuts the guide walls <NUM> of the knob engagement portion <NUM> if the catheter is to be connected to the MDU part. While <FIG> illustrates as if the knob engagement portion <NUM> permits the knob <NUM> to enter the knob engagement portion <NUM> in a state where the knob <NUM> is inclined, this is merely an exaggeration for helping understand the disclosure and <FIG> does not illustrate that such a clearance is present in the knob engagement portion <NUM>.

The generation of the torque <NUM> as shown indicates that the knob <NUM> enters the knob engagement portion <NUM> in a slightly inclined state. When the catheter <NUM> is attached to the MDU part <NUM>, an attachment force therefor is received by a contact part where the knob <NUM> contacts the knob engagement portion <NUM> and a shear force is generated in the projection portion <NUM> of the knob <NUM>. When the knob <NUM> is in the inclined state, a cross-sectional area receiving this shear force is smaller than that when the catheter is attached to the MDUpart <NUM> in a state where the knob <NUM> is not inclined. A high shear stress might be thereby generated in the projection portion <NUM> of the knob <NUM> and the projection portion <NUM> of the knob <NUM> might be broken or deformed.

The inventor of the present invention considered that it would be desirable to provide a structure for eliminating the torque <NUM> or generating an inverse rotational torque in order to make larger the cross-sectional area receiving the aforementioned shear force and to reduce the shear stress. Fortunately, it is clear from <FIG> that a rotation center of the torque <NUM> is defined by a position on the circumference of the knob <NUM> where the projection portion <NUM> is provided. For that reason, a surface, which abuts the ring member <NUM>, of the knob <NUM> is formed into a surface such that a flange portion of the knob <NUM> becomes the thickest in the same direction as the projection portion <NUM> and becomes the thinnest in the direction opposite to the projection portion <NUM>. Structuring the knob <NUM> as described above enables an upper end of a surface 301b to contact first the ring member <NUM> or the projection portion 401a in <FIG> when the catheter is pressed into the MDU part <NUM> to retreat the knob <NUM>, so that a state where the torque <NUM> shown previously is not present at all can be created or the torque in the opposite direction can be applied to the knob <NUM>. As a result, it is possible to secure a large cross-sectional area which receives the abovementioned shear force in the contact part between the projection portion <NUM> of the knob <NUM> and the guide walls <NUM> of the knob engagement portion <NUM>; therefore, it is eventually possible to reduce the shear stress and further alleviate the burden on the projection portion <NUM> of the knob <NUM>.

The embodiments according to the present invention have been described so far. In the present embodiments, the example where the present invention is applied to the imaging apparatus for diagnosis using optical coherence using the OCT or OFDI has been described. An apparatus that has not only a light transmission/reception unit but also an ultrasound transmission/reception unit provided in an imaging core and generating a tomographic image using optical coherence and a tomographic image using an ultrasound wave at one scan has recently been developed; therefore, the present invention may be applied to such an apparatus.

Claim 1:
An optical imaging apparatus (<NUM>) for diagnosis comprising
a drive unit (<NUM>) which functions as a power source for the rotation and axial movement of a drive shaft (<NUM>), and
a catheter (<NUM>) comprising said drive shaft (<NUM>) and a connector (<NUM>) for connecting the catheter (<NUM>) to the drive unit (<NUM>), wherein
the connector (<NUM>) comprises
a fiber end holding part exposing and holding an end surface of an optical fiber (<NUM>) in order to optically connect the catheter (<NUM>) to the drive unit (<NUM>);
an elastic body (<NUM>) buffering a load when the catheter (<NUM>) is connected to the drive unit (<NUM>); and
a member (<NUM>), provided between the elastic body (<NUM>) and the fiber end holding part, abuts the fiber end holding part when the fiber end holding part retreats due to pressing of the connector (<NUM>) into the drive unit (<NUM>) and is fixed to the elastic body (<NUM>),
characterized in that
a frictional force between the member (<NUM>) and the fiber end holding part is lower than a rotation suppression force of an engagement portion (<NUM>) of the drive unit (<NUM>) when the drive unit (<NUM>) is not driven and the connector (<NUM>) is pressed into the drive unit (<NUM>), the engagement portion (<NUM>) being configured to engage the fiber end holding part.