Abstract:
An imaging apparatus and method are provided. The probe for an imaging apparatus includes a manually manipulable proximal portion; a straight distal portion with a distal tip for locating at a site to define an observational field; and a curved portion between the proximal portion and the distal portion. The imaging method includes the steps of locating a distal tip of an imaging probe at a site to define an observational field; irradiating the observational field from the distal tip; and collecting a return signal at the distal tip; wherein the probe comprises a manually manipulable proximal portion. The apparatus and method provided herein are useful for various applications including but not limited to endomicroscopy and other microsurgical procedures performed under optical stereoscopic magnified visualization, such as neurosurgery, ENT/facial surgery and spinal surgery.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 12/756,692 filed Apr. 8, 2010, which claims the benefit of U.S. Provisional Patent Application No. 61/212,272 filed Apr. 8, 2009, the entire contents of all of which are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to an imaging method and apparatus, of particular but by no means exclusive application in endomicroscopy and in microsurgical and other procedures performed under optical stereoscopic magnified visualization, including neurosurgery, ENT/facial surgery and spinal surgery. 
     BACKGROUND OF THE INVENTION 
     One existing microscopic probe comprises an endoscope or endomicroscope, with an endoscopic head for insertion into a patient (through the mouth or anus) coupled to a laser source by an optical fibre or optical fibre bundle. Another microscopic probe is similar to this endoscope, but adapted for examining the skin. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, therefore, there is provided a probe for an imaging apparatus, comprising: a manually manipulable proximal portion; a straight distal portion with a distal tip for locating at a site to define an observational field; and a curved portion between the proximal portion and the distal portion; wherein the straight portion has a length of between 75 mm to 205 mm, the curved portion provides an angle between the proximal portion and the distal portion of between 120° and 150°, and the probe has a working length of between 125 mm to 300 mm. In certain particular embodiments, the curved portion provides an angle between the proximal portion and the distal portion of between 130° and 140°, and in a specific embodiment, the angle is approximately 135°. The probe may be an endoscopic probe, such as a confocal endoscopic probe. The probe may be, for example, a neurological probe, an ENT probe, an ultrasound probe, an OCT probe or a CARS probe. 
     It will be appreciated by those in the art that the distal tip refers to the terminal portion of the probe, and assumes different forms in each of these embodiments. For example, the distal tip of the ultrasound probe comprises an ultrasound head. The probe may have an orientation marking that allows identification of an orientation of the probe. The invention also provides an imaging apparatus, comprising the probe described above. 
     The apparatus may comprise an endomicroscope or other endomicroscopic apparatus. An endomicroscope is high resolution microscope capable of cellular, subcellular and surface and subsurface imaging, such as a miniature confocal microscope or other scanning microscope probe. The apparatus may be adapted to be used with a macroscopic visualization apparatus such as an operating microscope. As will be understood by those in the art, an operating microscope is the main visualization tool of a microsurgeon. It provides high magnification of tissue and thus allows very fine surgical procedures to be performed, though does not achieve cellular or subcellular resolution. An operating microscope is typically a direct viewing binocular device with a continuous passive optical path from tissue to observer. Thus, while an operating microscope is commonly referred to as a ‘microscope’, it should not be confused with an endomicroscope or an apparatus according to the present invention, which are specific types of microscopes that operate with at least an order of magnitude higher magnification than an operating microscope. The apparatus may be configured to orient an image collected with the probe so as to correspond to a normal field of view of a macroscopic visualization apparatus. The invention also provides an operating microscope that includes an imaging apparatus as described above. 
     According to a second aspect of the invention, therefore, there is provided an imaging method, comprising: locating a distal tip of an imaging probe at a site to define an observational field; irradiating the observational field from the distal tip; and collecting a return signal at the distal tip; wherein the probe comprises a manually manipulable proximal portion, a straight distal portion including the distal tip, and a curved portion between the proximal portion and the distal portion, and wherein the straight portion has a length of between 75 mm to 205 mm, the curved portion provides an angle between the proximal portion and the distal portion of between 120° and 150°, and the probe has a working length of between 125 mm to 300 mm. 
     In certain particular embodiments, the angle between the proximal portion and the distal portion is between of between 130° and 140°, and in a specific embodiment, the angle is approximately 135°. The probe may be an endoscopic probe, in which case the observational field is irradiated with light emitted from the distal tip, and the return signal comprises return light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be more clearly ascertained, preferred embodiments will now be described, by way of example only, with reference to the accompanying drawing, in which: 
         FIG. 1  is a schematic view of a confocal endomicroscopic apparatus according to an embodiment of the present invention; 
         FIG. 2  is a schematic view of the probe of the apparatus of  FIG. 1 ; 
         FIG. 3  is a schematic, perspective view of the probe of the apparatus of  FIG. 1 ; and 
         FIG. 4  is a schematic view of the probe of the apparatus of  FIG. 1  in use. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a schematic view of an endomicroscope system  10  according to an embodiment of the present invention. System  10  includes a laser source  12  with 488 nm wavelength output, a light separator in the form of an optical coupler  14 , a confocal endomicroscope probe  16 , a power monitor  18  and a detection unit  20 . System  10  includes a control box (not shown) that houses laser source  12  and detection unit  20  (in the form of a photomultiplier tube), and a computer (not shown) for receiving, storing and displaying data from detection unit  20 . Probe  16  includes an x-y scanning mechanism (not shown) so that light emitted by probe  16  has a point observational field that is scanned in a raster scan so that an image of the observational field—comprising a portion of a sample—can be collected and displayed. System  10  therefore also includes electrical cables for transmitting a scanning signal from the aforementioned control box to probe  16 , for powering the scanning mechanism. 
     In use, laser light from source  12  is transmitted by first optical fibre  22  to optical coupler  14 ; a first portion of the light is coupled into second optical fibre  24  and transmitted to probe  16 . A second portion of the light is coupled into third optical fibre  26  and transmitted to power monitor  18 . Probe  16  is adapted to be manipulated manually and placed against a sample to be imaged confocally. Before or during such imagining, the power deposited onto the sample can be monitored with power monitor  18  and the known ratio between the power coupled by optical coupler  14  into second fibre  24  and that into third fibre  26 . Light returned confocally by the sample and collected by probe  16  is transmitted back to optical coupler  14  and a portion of that return light is then coupled into fourth or return optical fibre  28  and transmitted to detection unit  20 . An image can then be constructed from the light detected by detection unit  20  and the aforementioned scanning signal, as the latter allows the origin within the sample of the return light to be ascertained. All the optical fibres  22 ,  24 ,  26 ,  28  are single moded at the wavelength of laser source  12 , though in some embodiments few- or multi-moded fibre may be used for fourth optical fiber  28 . 
     Probe  16  is shown in greater detail in  FIGS. 2 and 3 , and comprises a rigid steel housing  30  with a distal tip  32  adapted to be placed gently into contact with the sample. Housing  30  houses the terminal portion of second optical fibre  24 , the scanning mechanism for scanning the exit tip of second optical fibre  24 , and an optical train for receiving the scanned light from the exit tip of second optical fibre  24  and focusing it onto or into the sample. 
     System  10  is configured to be used with an operating microscope as is illustrated schematically at  40  in  FIG. 4 . In use, a macroscopic visualization apparatus in the form of operating microscope  42  is supported by arm  44  above a subject  46 , and defines an optical corridor  48  into an access corridor  50  created in the subject  46  to provide access to a site or sample  52  under examination. Probe  16 , once in position against sample  52 , can be viewed with operating microscope  42 . 
     Probe  16  is adapted to allow easy fine control of its distal tip  32  by manual  15  manipulation of a proximal portion  54  while distal tip  32  is viewed by operating microscope  42 , without probe  16  significantly obstructing optical corridor  48 . Probe  16  is thus adapted to be supported comfortably by a user for accessing sample  52  through access corridor  50 , and—referring to  FIG. 2 —has an insertable and essentially straight distal insertion portion  56  with a length  1  of 75 to 205 mm (and, in the illustrated embodiment, approximately 110 mm) and an outside diameter of approximately 6.6 mm. Proximal portion  54  of probe  16  and insertion portion  56  are coupled by a curved portion  58 , which provides approximately a 45° bend between those two portions, so that the angle θ between proximal portion  54  and insertion portion  56  is approximately 135°. Curved portion  58  allows distal tip  32  of probe  16  to be placed at sample  52  with manually manipulated proximal portion  54  held just outside access corridor  50 , without proximal portion  54  being in optical corridor  48 . Curved portion  58  thus allows the user to have a line of sight through operating microscope  42  along insertion portion  56  of probe  16  that is unobstructed by the user&#39;s hands. 
     In use, insertion of probe  16  into access corridor  50  is accomplished while operating microscope  42  is in place over access corridor  50  and, therefore, probe  16  is dimensioned to fit within the available working distances. For example, for a operating microscope  42  set at a 500 mm working distance and  35  arranged to focus on the deepest structures in an access corridor  50  of 200 mm depth, probe  16  should have a minimum reach of just over 200 mm (and, in practice, no less than 205 mm), provided by insertion portion  56 . However, this leaves an access working distance (i.e. between subject  46  and operating microscope  42 ) d of only 300 mm. Hence, insertion portion  56  (of ≧205 mm), curved portion  58 , proximal portion  54  and cable relief  60  should preferably be accommodated by this 300 mm, that is, have a “working length” (i.e. length in a direction parallel to insertion portion  56 ) of 300 mm. This defines the longest probe dimensions generally usable in this scenario. 
     In applications where higher magnifications of operating microscope  42  are employed, probe  16  should accommodate shorter working distances. This may  10  involve working at a distance of 200 mm from sample  52 , with sample  52  up to 70 mm deep. In this situation the minimum length of insertion portion  56  would be 75 mm and the total length of probe  16  less than 125 mm to allow probe  16  to be located in the working distance of 125 mm between the subject  46  and operating microscope  42 . 
     Thus the dimensions of probe  16  comprise or depend on the following:
         1) insertion portion  56 : 75 mm to 205 mm;   2) working length L measured in direction of insertion portion  56 : 125 mm to 300 mm;   3) handheld, proximal portion  54 , is adapted to sit at a comfortable angle for the position of the user&#39;s hand (extending from the bridge between the thumb and index finger to the tips of thumb and index finger);   4) angle θ provided by curved portion  58 : between 120° and 150° (and preferably between 130° and 140°, and in this embodiment approximately 135°) 25 between insertion portion  56  and handheld, proximal portion  54 ;   5) the combined length c of proximal portion  54  and the outer surface of curved portion  58  (together being that part of probe  16  likely to be manipulated by the user during use), in a direction parallel with proximal portion  54 , should not be less than the length required for the user to grip probe  16  along this combined length with a minimal number of fingers, while leaving a clear line of sight along the insertion portion  56 ; this minimum length is estimated to be about 59 mm;   6) combined length c depends on the balance of probe  16  and the available working space: probe  16  should not be unduly heavy in its balance point in respect to the bend; it is estimated that combined length c should not be greater than 75% of the length of the insertion portion  56 .       

     In addition, probe  16  is provided with orientation marking on insertion portion  56 , close to distal tip  32 , to allow orientation of the ultimate image relative to the field visualized by operating microscope  42 . The orientation marking, in the present embodiment, comprises a dot  62  close to distal tip  32 , representing “up” in the microscopic field. In other embodiments, however, the orientation 5 marking comprises:
         1) a plurality of visually distinguishable dots distributed around insertion portion  56 ;   2) axially oriented stripes indicating each quadrant (“north/south/east/west” markings);   3) nearly radial markings oriented at an angle to the axis of the scope with the angle being different in different quadrants so that observation from any side enables recognition of which side is being viewed;   4) colour coded markings (such as a plurality of dots, stripes or radial markings) to enhance the differences between different quadrants.
 
The orientation marking may also comprise any combination of these that serves to allow the identification of the orientation of probe  16 .
       

     System  10  orients its output of images collected with probe  16  to correspond to the normal field of view of operating microscope  42 , by aligning the “up” direction in that field of view (i.e. typically away from the user) and the top of an image collected with probe  16  when probe  16  is held in a relaxed, neutral manner. Hence, “up” in the confocal image is oriented so that advancing the arm in the direction of the user&#39;s forearm with straight wrist will move probe  16  “up” relative to the image. Swinging the arm right from the elbow with straight wrist would move probe  16  right relative to the displayed image, etc. 
     The optical path for the left and right eye through operating microscope  42  defines a coordinate system for up/down/left/right orientation of the user. The integrated camera of operating microscope  42  can thus be used to measure the outer orientation of probe  16  according to this coordinate system. The orientation of an image generated by system  10  can then be transformed to be correctly oriented to the coordinate system of operating microscope  42 . This can be done by rotating the endoscopic image, so that up/down/right/left 35 directions coincide with the coordinate system of operating microscope  42 . Alternatively, the image orientation of the endoscopic image can be adjusted to the coordinate system of the microscope by transforming the input signals for the scanning mechanism of system  10 , that is, by rotating the two axes of the scanning mechanism. 
     Modifications within the scope of the invention may be readily effected by those 5 skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove. 
     In the claims that follow and in the preceding description of the invention, except where the context requires otherwise owing to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Further, any reference herein to prior art is not intended to imply that such prior 15 art forms or formed a part of the common general knowledge.