Abstract:
A catheter assembly which is provided with a distally positioned magnetic resonance imaging coil, comprising a cable assembly having a proximal end and a distal end, the cable assembly further comprising an outer tube, a first electronics assembly disposed within the distal end of the cable assembly, a first fiber optic strand disposed within the tube, and connected to the first electronic assembly; and a tip assembly connected to the distal end of the cable assembly further comprising a thin structural wall forming a cavity, and a coil assembly disposed within the cavity. The catheter assembly enables high resolution magnetic resonance imaging of tissue proximate to the assembly, as well as other beneficial diagnostic and therapeutic procedures.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]    This application claims the benefit of the filing date of U.S. provisional patent application Serial No. 60/357,935 filed Feb. 19, 2002. 
     
    
     
         [0002]    This invention relates in one embodiment to a catheter assembly, and more particularly to a catheter assembly that includes the capability to perform magnetic resonance imaging.  
         FIELD OF THE INVENTION  
         [0003]    A catheter assembly which is provided with a distally positioned magnetic resonance imaging coil, thereby enabling high resolution magnetic resonance imaging of tissue proximate to the assembly.  
         BACKGROUND OF THE INVENTION  
         [0004]    Magnetic resonance imaging (MRI) is rapidly becoming an imaging method of choice for most non-invasive diagnostic procedures due to a variety of advantages. MRI is particularly effective in the imaging of internal organs, because images produced by MRI have superb soft tissue contrast, the imaging process is not obstructed by bone, and it is straightforward to obtain multi-plane images without repositioning patient. MRI is harmless to a majority of patients, as it requires no ionizing radiation or toxic contrast agents. It provides highly precise and clear images, thereby enabling functional analysis capabilities and a rapidly emerging medical practice of MRI-guided surgery.  
           [0005]    However there remains opportunity for further improvement of MRI. Present MRI capabilities are still unable to image disease conditions where exceptional tissue morphological or spectral resolution is required, such as the diagnosis of “vulnerable plaques” (see Peter Libby, “Atherosclerosis: The New View,” Scientific American, May 2002, Volume 286, number 5, pages 46-55). It is well known to those skilled in the art that reducing the distance between the tissues to be imaged by MRI and the receive coil in the MRI unit will enhance the signal from the tissues and thereby improve the quality of the magnetic resonance image, specifically by improving the tissue magnetic resonance image signal-to noise ratio.  
           [0006]    The present invention provides such a reduction in the distance between the tissues to be imaged by MRI. The present invention provides a small diameter MRI imaging coil that can be placed within the body, such as natural body openings or punctures through the skin, and to enable the coil to be positioned close to the tissues to be imaged, thereby providing significant improvement in morphological or spectral image quality due to the enhanced signal from the tissues and the increase in tissue magnetic resonance image signal-to-noise ratio that this closer proximity provides. The present invention may be further combined with other diagnostic and therapeutic features and capabilities useful for the diagnosis and treatment of diseases. In the preferred embodiment, the present invention is provided as a catheter device.  
           [0007]    Heretofore, a number of patents and publications have disclosed catheter devices, the relevant portions of which may be briefly summarized as follows:  
           [0008]    U.S. Pat. No. 6,236,879, for a “Fiber optic catheter system,” discloses “A catheter system including a catheter having a proximal end and a distal end and a device for determining the position of the distal end of the catheter relative to the position of the proximal end of the catheter, the device for determining the position including a glass fiber within a lumen of the catheter, the lumen being defined by a wall, a first polarization filter near the proximal end of the catheter, and a second polarization filter near the distal end of the catheter, wherein the first and second polarization filters are fixed with respect to the wall, and wherein the glass fiber is suitable for transporting polarized light while maintaining the direction of the polarization of the light substantially unchanged during torsional stress of the catheter.” 
           [0009]    U.S. Pat. No. 6,166,806, for a “Fiber optic catheter for accurate flow measurements,” discloses “A two-fiber optic probe or sensor performs accurate measurements of fluids flowing within a remote vessels, such as blood flowing within arteries or veins or fluid flowing within pipes.” 
           [0010]    U.S. Pat. No. 5,973,779, for a “Fiber-optic imaging probe,” discloses “A fiber-optic imaging probe is disclosed for use in dynamic light scattering applications. The probe includes two monomode optical fibers and two GRIN lenses to form a pair of identical fiber-lens combinations.” 
           [0011]    U.S. Pat. No. 5,415,653, for a “Optical catheter with stranded fibers,” discloses “A catheter having an axis extending between a proximal end and an opposing distal end includes a plurality of optical fibers arranged to spiral in a first direction to form a circumferential layer around the axis.” 
           [0012]    U.S. Pat. No. 4,991,590, for a “Fiber optic intravascular blood pressure transducer,” discloses “A device for the measurement of the blood pressure of a patient includes an arrangement for transmitting a light through an optical fiber; an arrangement for receiving and measuring a reflected light through an optical fiber; and a cylindrically shaped pressure sensor having a side window and a plate having two sections which moves in accordance with the applied blood pressure thereby causing the reflection and detection of different amounts of light based on the applied blood pressure at the window.” 
           [0013]    U.S. Pat. No. 5,919,135, for a “System and method for treating cellular disorders in a living being,” discloses “ . . . . The invention employs a computerized imaging system (such as CAT scan, MRI imaging, ultrasound imaging, infrared, X-ray, UV/visible light fluorescence, Raman spectroscopy, single photon emission computed tomography or microwave imaging) to sense the position of a drug infusing catheter within the body . . . . ” 
           [0014]    U.S. Pat. No. 6,026,316, for a “Method and apparatus for use with MR imaging,” discloses, “The invention is an apparatus and method for targeted drug delivery into a living patient using magnetic resonance (MR) imaging. The apparatus and method are useful in delivery to all types of living tissue and uses MR Imaging to track the location of drug delivery and estimating the rate of drug delivery. An MR-visible drug delivery device positioned at a target site (e.g., intracranial delivery) delivers a diagnostic or therapeutic drug solution into the tissue (e.g., the brain). The spatial distribution kinetics of the injected or infused drug agent are monitored quantitatively and non-invasively using water proton directional diffusion MR imaging to establish the efficacy of drug delivery at a targeted location.” 
           [0015]    U.S. Pat. No. 6,052,613, “Blood pressure transducer,” discloses, “This invention relates to a blood pressure transducer ( 8 ) and provides a safe and economical transducer by providing a novel optical fiber ( 80 ) made of a transparent elastomer. The present invention provides an invasive direct blood pressure transducer ( 8 ) of an external sensor system consisting of a catheter ( 1   a ), a pressure tub ( 6 ) connected to the catheter at one of the ends thereof and a pressure transducer ( 8 ) connected to the other end of the pressure tube ( 6 ), part of the pressure transducer is composed of an optical fiber ( 80 ) made of a transparent elastomer.” 
           [0016]    U.S. Pat. No. 5,445,151, for a “Method for blood flow acceleration and velocity measurement using MR catheters,” discloses “A method of magnetic resonance (MR) fluid flow measurement within a subject employs an invasive device with an RF transmit/receive coil and an RF transmit coil spaced a known distance apart. The subject is positioned in a static magnetic field. The invasive device is positioned in a vessel of a subject in which fluid flow is desired to be determined. A regular pattern of RF transmission pulses are radiated through the RF transmit/receive coil causing it to cause a steady-state MR response signal. Intermittently a second RF signal is transmitted from the RF coil positioned upstream, which causes a change in the steady-state MR response signal sensed by the downstream transmit/receive coil. This is detected a short delay time later at the RF receive coil. The time delay and the distance between the RF coils lead directly to a fluid velocity. By exchanging the position of the RF transmit and transmit/receive coils, retrograde velocity may be measured. In another embodiment, more RF coils are employed. The changed MR response signal may be sensed at a number of locations at different times, leading to a measured change in velocity, or acceleration of the fluid.” 
           [0017]    U.S. Pat. No. 6,134,003, for a “Method and apparatus for performing optical measurements using a fiber optic imaging guidewire, catheter or endoscope,” discloses, “An imaging system for performing optical coherence tomography includes an optical radiation source; a reference optical reflector; a first optical path leading to the reference optical reflector; and a second optical path coupled to an endoscopic unit.” 
           [0018]    U.S. Pat. No. 5,830,209, for a “Multi-fiber laser catheter,” discloses “Laser catheters according to the invention include multiple optical fibers for delivery of laser energy to a pre-determined treatment site in the therapeutic treatment of cardiac tissue. A fixation device fixes the distal end of the catheter to the treatment site. Temperature sensing devices disposed on the fixation device provide a temperature depth profile of the tissue treatment site, which can be used to control the treatment. Multi-piece, single-piece and porous tip catheters are disclosed.” 
           [0019]    U.S. Pat. No. 6,024,738, for a “Laser catheter apparatus for use in arteries or other narrow paths within living organisms,” discloses “A laser catheter for the treatment of lesions and plaque deposits in arteries and other narrow paths having a radiation assembly affixed to a flexible conduit. The conduit generally includes multiple lumens for the passage of an optical fiber, a guide wire, a cooling medium therethrough, or fluid for inflating an angioplasty balloon.” 
           [0020]    U.S. Pat. No. 5,634,720, for a “Multi-purpose multi-parameter cardiac catheter,” discloses “A multi-lumen, multi-purpose cardiac catheter which incorporates optical filaments and an optical coupler for use with external apparatus for determining the oxygen concentration in the blood of a patient under critical care conditions, as well as incorporating therein a thermal element useable with a second external apparatus for measurement of continuous cardiac output.” 
           [0021]    U.S. Pat. No. 5,435,308, for a “Multi-purpose multi-parameter cardiac catheter,” discloses “A multi-lumen, multi-purpose cardiac catheter which incorporates optical filaments and an optical coupler for use with external apparatus for determining the oxygen concentration in the blood of a patient under critical care conditions, as well as incorporating therein a heater coil useable with a second external apparatus for measurement of continuous cardiac output. The catheter also includes a thermistor and at least one injectate port for enabling the user to also conduct thermal dilution readings and obtain intermittent measurements of cardiac output. The combination of a thermal dilution catheter with a SVO2 catheter and a continuous cardiac output catheter gives the multi-purpose catheter above described substantial versatility as well as providing the user with a versatile cardiac catheter device which enables him to conduct multiple evaluations of disparate blood-related parameters which require the use of separate apparatus. Simply by switching from one external apparatus to the other, the user can obtain readings for different blood-related parameters useful in the treatment of the cardiac patient.” 
           [0022]    U.S. Pat. No. 6,036,654, for a “Multi-lumen, multi-parameter catheter,” discloses “A multi-lumen catheter capable of measuring cardiac output continuously, mixed venous oxygen saturation as well as other hemodynamic parameters. The catheter is also capable of undertaking therapeutic operations such as drug infusion and cardiac pacing. The catheter includes optical fibers for coupling to an external oximeter, an injectate port and thermistor for bolus thermodilution measurements, a heating element for inputting a heat signal and for coupling to an external processor for continuously measuring cardiac output, and a distal lumen for measuring pressure, withdrawing blood, guidewire passage or drug infusion. In a preferred embodiment, the catheter includes a novel lumen configuration permitting an additional infusion lumen for either fast drug infusion or cardiac pacing.” 
           [0023]    The disclosures of U.S. Pat. Nos. 6,236,879, 6,166,806, 5,973,779, 5,415,653, 4,991,590, 5,919,135, 6,026,316,6,052,613, 5,445,151, 6,134,003, 5,830,209, 6,024,738, 5,634,720, 5,435,308, and 6,036,654 are incorporated into this disclosure by reference.  
           [0024]    Despite the advances in capabilities that are described in these numerous catheter devices, there remain shortcomings in the capabilities of these catheter devices, and in magnetic resonance imaging, and in the use of magnetic resonance imaging when these catheter devices are present in the body. As was previously described, there is a need to reduce the distance between the tissue to be imaged by MRI and the receive coil in the MRI unit. Because of the relatively large distance between the external receive coil in present MRI systems and the internal tissue of the patient, the signal-to-noise ratio is insufficient to provide a satisfactory image of certain tissues in many circumstances.  
           [0025]    Many of these catheter devices are dangerous to the patient, because when such catheter devices are exposed to the MRI procedure, the metallic wires, tubing, structural supports, and other metallic leads therein are heated by the effect of the high frequency magnetic field. In addition, the functionality of these catheter devices is generally limited to a single purpose. It would be particularly beneficial to have a catheter device provided with multiple diagnostic features or capabilities in a single lead, and/or provided with diagnostic and therapeutic features in a single lead. In particular, it is highly desirable to incorporate an MRI coil into a catheter having additional diagnostic features or capabilities.  
           [0026]    It is therefore an object of this invention to provide a small diameter MRI imaging coil that can be placed within the body, such as natural body openings or punctures through the skin, and to enable the coil to be positioned close to the tissues to be imaged, thereby providing significant improvement in morphological or spectral image quality due to the enhanced signal from the tissues and the increase in tissue magnetic resonance image signal-to-noise ratio that this closer proximity provides.  
           [0027]    It is a further object of the present invention to combine with the present invention other diagnostic and therapeutic features and capabilities useful for the diagnosis and treatment of diseases.  
         SUMMARY OF THE INVENTION  
         [0028]    In accordance with the present invention, there is provided a catheter assembly comprising a cable assembly having a proximal end and a distal end, said cable assembly further comprising an outer tube, a first electronics assembly disposed within said distal end of said cable assembly, and a first fiber optic strand disposed within said tube and connected to said first electronic assembly; and a tip assembly connected to said distal end of said cable assembly further comprising a thin structural wall and a cavity formed within said thin structural wall, and a coil assembly disposed within said cavity, wherein said coil assembly is connected to said first electronics assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    The invention will be described by reference to the following drawings, in which like numerals refer to like elements, and in which:  
         [0030]    [0030]FIG. 1 is a schematic of a cross section of a catheter bundle of optical strands,  
         [0031]    [0031]FIG. 2 is a schematic of a cross section of a catheter bundle of optical and support strands,  
         [0032]    [0032]FIG. 3 is a schematic of a cross section of a catheter bundle of optical, strands, tubes, and support strands, and  
         [0033]    FIGS.  4 - 14  each schematically illustrate a numerous embodiments of a catheter cable and tip. 
     
    
       [0034]    The present invention will be described in connection with a preferred embodiment, however, it will be understood that there is no intent to limit the invention to the embodiment described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.  
       DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. In describing the present invention, the terms distal and proximal ends are used to describe the catheter embodiments disclosed herein. As used herein, the proximal end of a catheter is meant to describe the end thereof that is external to the body in which it is disposed. The distal end of a catheter is meant to describe the end thereof that is internal to the body in which it is disposed. The catheter terminates within such a body at the distal end of such catheter. FIGS.  4 - 14  of this disclosure depict distal ends of catheters of the present invention.  
         [0036]    [0036]FIG. 1 is a cross-sectional view of a catheter cable assembly  100 . Such catheter cable assembly  100  is typical of prior art optical cable assemblies. Reference may be had, e.g., to U.S. Pat. No. 4,784,461 (optical cable with improved strength), U.S. Pat. No. 6,259,843 (optical cable), U.S. Pat. No. 5,611,016 (dispersion balanced optical cable), U.S. Pat. No. 4,911,525 (optical communications cable), U.S. Pat. No. 4,798,443 (optical cable), U.S. Pat. No. 5,634,720 (multi-purpose multi-parameter cardiac catheter), and the like. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.  
         [0037]    Referring to FIG. 1, and in the preferred embodiment depicted therein, six fiber optic strands  102  are shown surrounding a central fiber optic strand  103 . It is to be understood that the number of strands  102  in the assembly  100  of the catheter cable may be more or less than the number depicted. In one embodiment, from about 1 to about 10 such fiber optic strands  102  may be used.  
         [0038]    Referring again to FIG. 1, it is preferred that each such fiber optics strand  102 / 103  be comprised of a core  108 . This core  108  preferably consists of or consists essentially of silicon dioxide (silica), preferably of high purity. The core  108  generally has a symmetrical cross section, such as a circular cross section; and it usually has a diameter of from about. 1 to about 100 microns. In one embodiment, core  108  has a diameter of from about 2 to about 10 microns.  
         [0039]    Cladding  106  preferably envelops the core  108 . In the embodiment depicted, the cladding  106  has an outside diameter that is substantially larger than core  108 , being at least about 1.1 times as large as the diameter of the core. In general, the cladding generally has a diameter of from about 5 to about 150 microns. In one embodiment, the optical cladding  106  has a thickness of approximately 60 micrometers and is itself preferably surrounded by a protective film  104 . The protective film  104  preferably consists essentially of plastic material and, in one embodiment, has a thickness of approximately 1 micrometer. In the embodiment depicted in FIG. 1, six (6) of these fiber optic strands  102  comprising core  108  and cladding  106  are positioned around a central fiber optic strand  103 .  
         [0040]    In the embodiment depicted, the seven fiber optic strands  102 / 103  of FIG. 1 are surrounded by a protective layer comprising a sleeve or tube  110 , which keeps the seven individual, strands  102 / 103  together. Such outer tubing  110  may be made from flexible material such as, e.g., plastic.  
         [0041]    The regions  114  disposed between fiber optic strands  102 / 103  in one embodiment are preferably filled with additional material  114  to provide for increased structural strength of the overall assembly  100 . In one embodiment, the additional material  114  is plastic material. In another embodiment, the additional material  114  is steel fiber or carbon fiber. In one embodiment, it is preferred that none of the materials within the cable assembly  100 , and/or the cable assembly  120  (see FIG. 2) be electrically conductive.  
         [0042]    In one embodiment, illustrated in FIG. 1, some or all of the outer regions  112  are filled with the same additional material(s) within spaces  114 , and/or different additional material. Furthermore, some of these spaces  114 / 112  may be filled with additional material, whereas others are not.  
         [0043]    Fewer or more interstrand regions  114 / 112  will exist depending on the total number of strands comprising the catheter cable assembly  100 . The choice of material depends, in part, on the desired flexibility and strength of the catheter cable assembly  100 .  
         [0044]    [0044]FIG. 2 is a sectional view of an optical cable assembly  120  in which a central strand  122  is preferably comprised of, or consists essentially of, a single, solid material. In this embodiment, strand  122  may be used to give the catheter cable additional structural strength or flexibility. The additional, solid material  122  may be a plastic material, may be optically inert, and may preferably be electrically insulative.  
         [0045]    It is preferred that the material  122  have low magnetic susceptibility. Thus, e.g., the material  122  can be made of glass-epoxy, quartz glass, or other material having a low magnetic susceptibility. As is known to those skilled in the art, magnetic susceptibility is measured by the ratio of the intensity of magnetization produced in a substance to the magnetizing force or intensity of field to which it is subjected.  
         [0046]    [0046]FIG. 3 depicts another embodiment of another cable strand assembly  130  in which two of the fiber optics strands  102  of FIG. 2 are replaced by lumens  132  and  134 .  
         [0047]    As will be apparent, these lumens may comprise and/or convey cooling fluid(s) or gas(es), heat exchange fluids or gases, and the like. The lumens  132  and/or  134  may be pressured. The lumens  132  and/or  134  may be partially evacuated.  
         [0048]    In the preferred embodiment depicted in FIG. 3, lumens  132  and/or  134  preferably comprise a wall  136  of approximately 1 to 2 micrometers thick and an axial void  138  of approximately 125 micrometers in diameter.  
         [0049]    [0049]FIG. 4 is a schematic representation of an assembly  200  comprised of a cable assembly  204  and a catheter tip assembly  201  connected to the cable assembly  204  at the distal end of the catheter (not shown).  
         [0050]    As is known to those skilled in the art, a catheter is a tubular instrument adapted to allow passage of fluid, other material, or energy from or into a body cavity or blood vessel. As used herein, the term “catheter” refers to a tubular cable assembly connected to a tip comprised of a thin structural wall and a cavity enclosed therein, containing means for converting photonic energy to electrical energy, and vice versa.  
         [0051]    Referring again to FIG. 4, catheter tip assembly  201  comprises a thin structural wall  202  containing a volume or cavity  218 , within which a variety of small devices may be disposed. Catheter cable  204  preferably comprises at least two tubes  206  and  208  and a fiber optics strand  210 . These tubes/strand  206 / 208 / 210  preferably pass into a sealed chamber  212 . Disposed within the volume  214  of the chamber  212  is an electronic transducer assembly  216  connected to the fiber optics strand  210  and also connected to a coil assembly  220  situated outside the chamber  212 , but within the tip volume  218 . The connection of the electronic assembly  216  to the coil assembly  220  is preferably made by conductors  222  and  224 .  
         [0052]    The coil assembly  220  is preferably one or more pick-up coils and/or one or more transmit coils suitable for magnetic resonance imaging procedures. As is known to those skilled in the art, pickup coils are adapted to sense a signal or quantity. Reference may be had, e.g., to U.S. Pat. No. 4,691,164, which also describes coil  120  as being a “transmitter/receiver.” Reference also may be had, e.g. to U.S. Pat. Nos. 4,450,408, 6,278,277, 5,061,680, 5,158,932, and the like. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.  
         [0053]    Referring again to FIG. 4, the lumens  206  and  208  may be used, e.g. to cycle air through the chamber  212  to provide a cooling means for the electronics assembly  216 . Such a flow may be made into and out of chamber  212 , as is indicated by the flow direction arrows  226  and  228 . Alternatively, a liquid may be cycled through the chamber  212  for the purposes of assisting and controlling the dissipation of heat generated by the electronics assembly  216 .  
         [0054]    In another embodiment (not shown), the catheter cable assembly  204  of FIG. 4 additionally contains a strand suitable for steering the catheter tip through the lumens of the body.  
         [0055]    In another embodiment, illustrated in FIG. 5, one preferred assembly  250  of the distal end of the catheter cable assembly  252  and catheter tip  254  is illustrated. The cable assembly  252  consists of at least two strands  256  and  258 . As will be apparent, the assembly  250  includes two separate electronic assemblies  260  and  262 , and two strands  256  and  258 .  
         [0056]    Referring to FIG. 5, and in the preferred embodiment depicted therein, strand  256  is preferably connected to an electronic assembly  260  that preferably houses means for converting and storing energy conveyed to it through strand  256 .  
         [0057]    In one embodiment, depicted in FIG. 5, strand  256  is hollow tube or lumen filled with a gas (such as air), and/or a liquid, and/or a solid material(s). In this embodiment, the power assembly  260  may contain a piezoelectric crystal (not shown), one or more capacitors (not shown), one or more inductors (not shown), one or more resistors (not shown), and other electronic components, circuits, and assemblies (not shown).  
         [0058]    Referring again to FIG. 5, and in one embodiment, the end of lumen  256  is connected to the piezoelectric crystal (not shown) in such a way as to oscillate the piezoelectric crystal as the pressure in the tube  256  is oscillated by an external means (not shown). By such a device, one can convert a pressure signal into an electrical signal, and vice versa. If one were to add photoelectric devices to this assembly, one would also be able to convert pressure signals to photonic signals, and vice versa.  
         [0059]    As will be apparent, in the embodiment depicted in FIG. 5, hydraulic energy/signals may be converted to electrical energy/signals, and vice versa, by piezoelectric transducer assembly  260 . Thus, in addition to conveying information photonically, the device  250  is also capable of transmitting information hydraulically.  
         [0060]    In another embodiment, strand  256  is a fiber optics cable. Power assembly  260  may contain a photovoltaic cell (not shown) along with a capacitor (not shown). An external laser diode (not shown) may preferably send light through the strand  256  to the assembly  260  where it is converted to an electrical potential by a photovoltaic cell (not shown) which charges the capacitor.  
         [0061]    In the embodiment illustrated in FIG. 5, strand  258  is preferably a fiber optics strand to be used for sending signals to the proximal end of the catheter cable  252 . Strand  258  is preferably connected to an electronics assembly  262  at the distal end of the cable assembly  252 . The electronics assembly  262  is preferably powered by the power assembly  260  through connection  264 . The electronics assembly  262  preferably has means (not shown) for converting and sending signals received by one or more coils  268  through optics strand  258 . The coils  268  are connected to the electronics assembly  262  via lines  270  and  272 . In another embodiment, not shown, the coils  268  are telemetrically connected to the electronics assembly  262 .  
         [0062]    In one embodiment, not shown, several coils  268  are positioned at various angles to enhance the imaging ability of the catheter. As will be apparent, the angles at which radiation impacts an antenna often affect its receiving capabilities.  
         [0063]    In another embodiment, not shown, the coil  268  may be rotated and/or translated into various angles and locations within the tip assembly by an actuator (not shown) controlled by electronics assembly  262 .  
         [0064]    [0064]FIG. 6 illustrates another embodiment of this invention comprising an assembly  300  comprised of a catheter cable assembly  302  and a distal end tip  304 . The cable assembly  302  contains at least tubes  306  and  308  connected to a power assembly  312 , and at least one fiber optics strand  310  connected to an electronics assembly  314 . In this embodiment, liquid (or gas) may be cycled through the power assembly  312  which is so constructed, in one embodiment, as to convert the motion of the fluid through assembly  312  or to convert the contents of the liquid (or gas) into electrical energy suitable for running the electronics in assembly  314 . The liquid or gas, e.g. may contain electrolytes, and assembly  312  may be so constructed as to comprise a battery. The power assembly  312  is connected to the electronics assembly  314  via line  316 .  
         [0065]    In one embodiment, the electronics assembly  314  is connected to the fiber optics strand  310  and is used to convey signals obtained from coils  320 , which are connected to the electronics assembly  314  via lines  322  and  324 , through the optics strand  310 . Additionally, strand  310  may be used to send signals from the external proximal end (not shown) of the cable assembly  302  to the electronics assembly  314 .  
         [0066]    In another embodiment depicted in FIG. 7, an assembly  350  is shown comprising a catheter cable assembly  352  and a catheter tip assembly  354 . The catheter cable assembly comprises at least 3 strands,  356 ,  358 ,  360 .  
         [0067]    In this embodiment, strands  356  and  358  are connected to a subassembly  370 . Subassembly  370  is connected to a syringe needle  372  that has an open orifice  374  in the tip  354 . In one embodiment of the configuration depicted in FIG. 7, strand  356  is a hollow tube and strand  358  is a fiber optic. Subassembly  370  may consist of a reservoir (not shown) and electronic means (not shown) for controlling the release of the reservoir contents through the needle  372 . Strand  356  is then used to fill the reservoir with the desired solution, e.g. an MRI contrast agent or drug, or topical ointments, etc. Strand  358  may be used to communicate externally with the electronics of subassembly  370  to signal when the solution stored in the reservoir is to be released.  
         [0068]    In another embodiment of FIG. 7, not shown, the needle  372  is used to obtain fluid samples from the body. In this embodiment, tube strand  356  is used to provide a vacuum pressure suitable for drawing the bodily fluid through the needle  372 . Subassembly  370  is so constructed as to provide means for controlling the drawing of a fluid through the needle  372 . Subassembly  370  may also contain medical analyses means (not shown) suitable, e.g. for detecting glucose levels in blood, for detecting toxins in the blood, for determining the pH level of the sampled fluid, etc. Subassembly  370  also preferably has means (not shown) for sending data pertaining to the results of such analysis through the fiber optics strand  358  to an external monitor or physician (not shown). Additionally, strand  358  may be used to send command signals from an outside physician to the subassembly  370  to control the drawing of fluid and to direct the analysis of said drawn fluid.  
         [0069]    Referring again to FIG. 7, the electronics assembly  362  is preferably connected to the fiber optics strand  360  and is used to convey signals obtained from one or more coils  364 , which are connected to the electronics assembly  362  via lines  366  and  368 , through the optics strand  360 . Additionally, fiber optics stand  360  may be used to send signals from the external proximal end (not shown) to the cable assembly  352  to the electronics assembly  362 .  
         [0070]    [0070]FIG. 8 depicts another embodiment of an assembly  400  comprised of a catheter cable assembly  402  and a tip assembly  404 . The catheter cable assembly  402  comprises of at least 3 strands  406 ,  408 ,  410  that, in this embodiment, are all preferably fiber optics strands. In this embodiment, strands  406  and  408  are connected to optical electronics assembly  420 . Also connected to optical electronics assembly  420  is an optics conduit assembly  422  that is connected to a lens assembly  424  built into the outer surface of the tip assembly  404 . The optical electronics assembly  420 , optics conduit assembly  422  and lens assembly  424  may comprise the components of an optical biopsy assembly or may provide means for performing Optical Coherent Tomography. In these cases, the optics strand  406  may convey the light to be used for the optical biopsy procedures, while optics strand  408  is used by the electronics assembly  420  to convey the biopsy information back to the physician or external monitoring device (not shown). Additionally, optical electronics assembly  420 , optics conduit assembly  422 , and lens assembly  424  may be used for laser ablation at the tip site. Laser light may be generated by a laser diode built into optical electronics assembly  420 , or may be obtained from an external source through strand  406 . In another embodiment, the functionality of strand  406 , optical electronics assembly  420 , optics conduit assembly  422  and lens assembly  424  is switched between performing, e.g., optical coherent tomography and laser ablation. Such functional switching may be controlled externally by communication between an external physician and the optical electronics assembly  420  Via fiber optic strand  408 .  
         [0071]    In another embodiment, and continuing to refer to FIG. 8, the electronics assembly  420  and optics assemblies  422  and  424  are utilized to provide video images of the external tip environment (not shown) through the optical strand  406  to the proximal end of the catheter.  
         [0072]    Continuing to refer to FIG. 8, the electronics assembly  412  is preferably connected to the fiber optics strand  410  and is used to convey signals obtained from coils  414 , which are connected to the electronics assembly  412  via lines  416  and  418 , through the optics strand  410 .  
         [0073]    [0073]FIG. 9 depicts another embodiment of an assembly  500  comprising a cable assembly  502  and a tip assembly  504 . In this embodiment, at least one fiber optic strand  508  is disposed within the catheter cable assembly  502 . It is connected, within a tip cavity region  506 , to an electronics assembly  510 . The electronics assembly is connected to at least one coil  512  by means of lines  514  and  516 . Signals from the coils  512  are converted into light signals by the electronics assembly  510  and sent out through the fiber optic strand  508 . The power to run the electronics assembly  510  is preferably provided by a power electronics assembly  520 , which is connected to at least one coil  518  via lines  522  and  524 . In magnetic resonance imaging (MRI) technology, external radio frequency electromagnetic waves are applied to the a body in order to excite protons in the nuclei of the body&#39;s atoms. The coils  518  and power electronics  520  are so designed as to resonate at the externally applied radio frequency wave frequency. In this way, energy may be delivered, and possibly stored in capacitors (not shown) within power electronics assembly  520 . The electrical power is provided to the electronics assembly  510  via line  526 .  
         [0074]    [0074]FIG. 10 depicts another embodiment of an assembly  550  comprising a cable assembly  552  and a tip assembly  554 . In this embodiment, the cable assembly  552  comprises of at least one optics strand  556  connected to an electronics assembly  558 . The electronics assembly  558  is connected to at least one pickup coil  560  via lines  562 ,  564 . The electronics assembly  558  converts the signals picked up by the coils into light signals suitable for transmission through the fiber optics strand  556  and generates and transmits such signals. Additionally, other sensors  566 , and electromagnetic emitters  570  are connected to the electronics assembly  558  via lines  568  and  572 . Sensors  566  and emitters  570  are also connected to, and may protrude through, the tip  554 . Sensors  566  may be used, e.g., to sense the temperature, blood pressure, blood flow rate, etc. within a body. Emitters  570  may be used, e.g. to emit millimeter electromagnetic energy, or heat, or other energy. The electronic assembly  558  collects sensed data from the sensors and converts the data into light signals suitable for transmission through the fiber optics strand  556 . Electronics assembly  558  also controls and coordinates which datum from which sensor and/or coil is to be transmitted through fiber optics strand  556  at ay given time.  
         [0075]    [0075]FIG. 11 depicts another embodiment of an assembly  600  comprising a cable assembly  602  and a tip assembly  604 . The cable assembly  602  comprises at least 2 fiber optic strands  606 ,  608  connected to an electronics assembly  610 . The electronics assembly  610  is connected to at least one sensing device, including, but not limited to, a pickup coil  612 . Other, optional, sensing devices are labeled as  618 . The electronics assembly  604  is connected to the pickup coil  612  via lines  614 ,  616 . The other sensing devices are connected to the electronics assembly  610  via line  620 .  
         [0076]    In this embodiment, laser light, or other suitable light, is sent from an external source (not shown) through fiber optics strand  606  as indicated by arrow  622  to the electronics assembly  610 . The electronics assembly modifies the light in a predetermined way to encode the signals from the coil  612  and/or the sensing devices  618  and then channels the light through the fiber optics strand  608 , as indicated by arrow  624 . In this way, a source for generating light is not required at the electronics assembly  610 . One method for encoding a signal is to construct electronics assembly  610  with optical components suitable for causing phase shifts in the light  622  based on signals from the coil  612  or other sensing devices  618 . Then, by externally comparing the phase between the light sent in  622  with that of the light sent out  624 , a means for transmitting sensed data is realized. Other means for altering the incoming light  622  before channeling it out as  624  may be utilized. Using such techniques reduces the power requirements of the electronics assembly  610  since, in these embodiments, electronics assembly  610  does not need a light source. Also, this provides a way to utilize light sources that might not otherwise be applicable if it were required to be part of the electronics assembly  610  because of size constraints, power requirements, or heating problems. Using an external light source as described here eliminates these constraints.  
         [0077]    In another embodiment depicted in FIG. 12, a distal end catheter assembly  650  comprises a catheter cable assembly  652  and a tip assembly  654  suitable for performing radio frequency ablation within a body. Other frequencies of electromagnetic energy outside of the radio frequency range may also be utilized. The catheter cable assembly comprises at least one optical strand  656  connected to an electronic assembly  658  which contains means for converting the optical energy sent from the external proximal end of the catheter (not shown) to the electronic assembly  658  at the distal end of the catheter. Such means for converting the optical energy to electrical energy may be, e.g., a photovoltaic cell. Electronic assembly  658  may also be comprised of other electronic components as well. The electronic assembly  658  is connected to an radio frequency signal generator  660  via line  668 . The radio frequency signal generator  660  is connected to one or more coils  662  suitable for performing, e.g. radio frequency ablation, via lines  664 ,  666 .  
         [0078]    In another embodiment (not shown) the radio frequency generator of the embodiment shown in FIG. 12 is removed. In this case, the optical energy sent to the electronic assembly  658  of FIG. 12 is pulsed at the desired radio frequency. Other frequencies outside of the radio frequency range may also be utilized. The electronics assembly  658  of FIG. 12 is correspondingly modified to connect directly to the coils  662  of FIG. 12. In this way, the amount of electronics, power requirements, heat generation and possibly other constraints in the design of the catheter tip may be reduced.  
         [0079]    [0079]FIG. 13 depicts another embodiment of an assembly  700  comprised of a catheter cable assembly  702  and a tip assembly  704 . The catheter cable assembly  702  comprises 2 strands  706 ,  708  that, in this embodiment, are all preferably fiber optic strands. In this embodiment, strand  706  passes through the tip area  712  and connects to a lens assembly  710 . Thus, electromagnetic energy (such as, e.g., optical energy, microwave energy, millimeter wave energy, and the like) from a source (not shown) at the remote proximal end of the catheter cable  702  may be directly applied to the tip  704  and to the external environment disposed beyond it.  
         [0080]    In one embodiment, the electromagnetic energy conveyed through  706  is outside of the visible electromagnetic spectrum, includes the near infrared, and/or infrared and/or ultraviolet, and/or other ranges of the electromagnetic spectrum. In another embodiment, and continuing to refer to FIG. 13, the optical energy passed through the strand  706  and out through the lens assembly  710  is a laser light adapted to apply heat to the environment proximate to the tip. In another embodiment, the laser energy may be utilized for cauterization.  
         [0081]    Continuing to refer to FIG. 13, the electronics assembly  714  is preferably connected to the fiber optics strand  708  and is preferably used to convey through optics strand  708  the signals obtained from coils  716  that are connected to the electronics assembly  714  via lines  718  and  720 .  
         [0082]    [0082]FIG. 14 depicts another embodiment of the invention, illustrating an assembly  750  comprised of a catheter cable assembly  752  and a tip assembly  754 : The catheter cable assembly  752  comprises two strands  758 ,  760 . Strand  758  is preferably a hollow lumen or tube suitable for transporting a gas or a liquid. Strand  760  is preferably a fiber optic strand. In this embodiment, strand  758  connects to one or more inflatable bladders  764  disposed within the tip volume  756 . The connection of the tube  758  to the bladder(s) is accomplished via connection assembly  766 . The bladder is further enclosed within a chamber  776  within the tip volume  756  which provides the necessary constraints on the bladder  764  such that when a gas or liquid is pumped into the bladder  764 , said bladder  764  can not extend into the tip volume  756 . The bladder  764  is so disposed as to be able to expand out of the tip  754  through orifice  762  of tip  754 . In this way, the catheter tip  754  may be stabilized within the body environment (not shown) to which said tip is introduced. Applying a partial vacuum to the tube  758  retracts the bladder  764 .  
         [0083]    Continuing to refer to FIG. 14, the electronics assembly  768  is preferably connected to the fiber optics strand  760  and is used to convey signals obtained from one or more coils  770 , which are connected to the electronics assembly  768  via lines  772  and  774 , through the optics strand  760 . The electronic assembly  768  may contain means for decoupling the coils  770  with respect to the externally applied (not shown) magnetic resonance imaging radio frequency and/or gradient magnetic field oscillations. Additionally, electronics assembly  768  may contain means for converting the signals picked up by the coils  770  into digital signals or analog signals suitable for transmission through the fiber optics strand  760 . Multiplexing of signals may also be used to transmit and/or receive signals through fiber optics strand  760 .  
         [0084]    In another embodiment (not shown), one or more bladders are disposed along the cable assembly  752  of FIG. 14, rather than or in addition to the bladders in the tip  754  of FIG. 14.  
         [0085]    In another embodiment (not shown), extendable and retractable wires are used to increase the stability of the catheter tip.  
         [0086]    It is, therefore, apparent that there has been provided, in accordance with the present invention, a catheter assembly that is compatible with and that may be subjected to a magnetic resonance imaging process without adverse effects on the assembly, or the patient within whom it is disposed. While this invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art, and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.