fig1 of the drawings schematically illustrates a unit of magnetic resonance image ( mri ) type cross - sectioning medical imaging equipment 10 with which the stereotactic apparatus 12 of the present invention may be utilized to assist the using physician in advantageously locating , vectoring , and inserting a medical needle - device relative to a patient anatomical target of interest . as previously suggested , equipment 10 might also take the form of a unit of computed tomography image ( cti ) type of medical imaging equipment or other body cross - sectional imaging system . such equipment typically is provided with a patient table 14 upon which the patient p to receive treatment is appropriately positioned . in most cross - sectional imaging equipment arrangements , the patient support table 14 generally may be incrementally indexed along its longitudinal axis to any of numerous different and repeatable positions at which the cross - sectional imaging plane 16 of the equipment intersects the patient &# 39 ; s body ( and stereotactic apparatus 12 ) at different points of anatomical interest . in other forms of such medical imaging equipment , the patient support table remains in a transiently fixed position and the equipment scanner and cross - sectional imaging plane are moved relative to the table as a gantry . in the case of mri imaging equipment , images of many different patient sectional planes can be obtained without moving either the patient or the equipment so long as the patient &# 39 ; s body region of interest is located generally in the center of the equipment magnet / magnetic field . also , fig1 additionally schematically illustrates the conventional x - y - z coordinate axis scheme that pertains to equipment 10 and that is sometimes referred to describe particular angular and directional relationships . note that the equipment cross - sectional imaging plane 16 corresponds to the x - y coordinate plane and that the longitudinal axis of the patient support table 14 parallels the x coordinate axis . the drawings do not illustrate the inclusion and positioning of a conventional equipment cathode ray tube monitor that appropriately displays the equipment - generated patient cross - sectional images including an image that contains the patient anatomical target of particular interest . throughout the specification and claims of this application the repeated use of specific co - ordinate directions is intended in a relative sense and not an absolute sense . different equipment construction or operation modifications may be effected that result in changes of absolute co - ordinate direction without a relative change in co - ordinate direction . fig2 illustrates the fig1 component parts after the patient p and equipment support table 14 have moved to a position whereat equipment cross - sectional imaging plane images appearing on the equipment monitor screen intersect the patient &# 39 ; s anatomical target of interest . in the drawings the patient p is shown as being in a decubitus position as for procedures involving the human female breast . however the stereotactic apparatus of the present invention may be utilized for medical procedures involving and other parts of the human body such as head , abdomen and extremities . referring to fig3 through 6 , stereotactic apparatus 12 is more clearly illustrated as being basically comprised of base subassembly 18 , movable compression plate subassembly 20 that cooperates with vertical support posts 22 mounted on subassembly 18 , and needle - device locator subassembly 24 mounted on compression plate subassembly 20 . base subassembly includes a frame member 26 , a base member 28 positioned within and rotatable relative to frame member 26 , and double - v reference pattern 30 ( fig5 and 6 ) which is shown affixed to the underside of an equipment surface coil antenna 32 mounted on base member 28 . where pattern 30 is affixed to imaging equipment element 32 it must be with assurance that element 32 rotates with base member 28 when that member is rotated as for angularity adjustment purposes . otherwise , double - v reference pattern may be directly affixed to base member 28 . frame member 26 can be retained in position on equipment patient support table 14 by removable tape or other functionally equivalent means . such frame member retention minimizes the likelihood of assist apparatus 12 accidentally being moved relative to patient p during use . details of double - v reference pattern 30 are best shown in fig5 and 6 . basically , such reference pattern is comprised of two v - configured elements 34 and 36 with each such &# 34 ; v &# 34 ; being contained within an equally - sized and adjoining imaginary true square . thus , the angle that is included between the legs of each &# 34 ; v &# 34 ; will be approximately 53 degrees , 8 minutes ( 2 times are tangent 0 . 5 ), and each right - angled distance between the legs of an element 34 or 36 will be equal to its distance from the &# 34 ; v &# 34 ; apex along the &# 34 ; v &# 34 ; axis of symmetry . for mr imaging applications of the present invention , the legs of &# 34 ; v &# 34 ; elements 34 and 36 are essentially constructed of small - diameter plastic tubes filled with an image - conspicuous sterile contrast agent such as ky jelly . the filled plastic tube legs are secured to the underside of equipment surface antenna 32 ( or to base member 28 ), by conventional permanent adhesive . with respect to ct imaging , all apparatus parts are imaged -- metal , plastic , etc . also , frame member 26 and base member 28 of subassembly 18 are provided with the respective etched or printed indicia designated 38 and 40 , respectively , and such are used in the hereinafter described process of properly aligning base member 28 relative to the plane that contains equipment cross - sectioning image plane 16 . basically , the arrow indicia 38 and the 0 ( zero ) value of scale indicia 40 each coincide with the illustrated axis of symmetry 42 of double - v reference pattern 30 when the x - axis of needle - device locator subassembly 24 and of body - part compression plate subassembly 20 are at right angles ( along line 43 ) to symmetry axis 42 . reference pattern 30 also has an axis of asymmetry 43 that is oriented at right angles to axis 42 . body - part compression plate subassembly 20 is basically comprised of a plate member 50 having affixed sleeves 52 ( and included sleeve clamping screws ) that cooperate with vertical posts 22 and also having interior opening 54 that is filled with a very taut open mesh element 56 which has a very high degree of net open area similar to that of the stringing in a tennis racquet . needle - device locator subassembly 24 is basically comprised of x - axis rails 60 and 62 and z - axis rail 64 , each affixed to plate member 50 , and a needle - device guide carrier 66 slidably mounted on rails 60 and 62 and having and internal open slide 68 that co - operates with the z - axis rails 70 of carrier 66 . located within open slide element 68 is the hereinafter detailed and described readily - removable , needle - device guide subassembly 80 also provided with a double - v reference pattern ( see fig8 ) that differs from double - v reference pattern 30 provided with assist apparatus base member 28 . subassembly 24 also advantageously is provided with a remote control positioner that includes sheathed , push - pull cables 82 and 84 . cable 82 is connected to a z - axis rail 70 of carrier 66 and functions to move that carrier in x - axis directions ; cable 84 is connected to open slide 68 and functions to move that slide in z - axis directions . optional clamping screws 86 are provided for securing or locking carrier 66 relative x - axis rails 60 and 62 when it has been moved to its position for subsequent needle - device insertion . in drawing fig1 and 2 , manual manipulation of positioning cables 82 and 84 is contemplated . however , automatic remote actuation and control of positioning cables 82 and 84 is quite feasible and desirable . one manner for accomplishing that objective is schematically illustrated in fig1 . fig8 and 9 provide details of readily - removable , needle - device guide subassembly 80 . that subassembly includes an open rigid box frame having top and bottom face frames 86 and 88 joined into a unitary structure by side legs 90 . the interior faces of face frames 86 and 88 each support an attached v - configured reference pattern element 92 or 94 which together constitute a &# 34 ; stacked &# 34 ; double - v reference pattern . although v - shaped reference pattern elements 92 and 94 have the same geometric configuration as v - shape elements 34 and 36 of base member 28 , such have significantly reduced overall dimensions . superimposed on and adhered to the exterior face of each of face frames 86 and 88 is a transparent , perforable film or diaphragm element 96 having v - shaped transverse reference lines 98 and angled reference lines 100 printed thereon . lines 98 conform to the same measurement as the distance between the two image conspicuous limbs 92 , 94 . lines 100 are spaced at millimeter distances parallel to the closest image conspicuous limb 92 , 94 . short and straight , image - conspicuous , fiduciary elements 102 and 103 are adhered to the inner faces of face frame elements 86 and 88 , respectively , and in alignment with one of transverse lines 98 ( e . g ., the 30 millimeter line ), and are available for use in verifying subassembly position accuracy relative to later - described visual scales provided on the remote ends of push - pull positioning cable elements 82 and 84 . refer to fig1 . also , scale 104 is printed on perforable diaphragm elements 96 and are utilized at the time vectoring and inserting the physician - held medical needle - device into needle - device guide subassembly 80 following subassembly location above the patient anatomical target of interest . &# 34 ; v &# 34 ;- elements 92 and 94 are constructed in the same manner as the similar elements of image - conspicuous reference pattern 30 , and when being &# 34 ; stacked &# 34 ; are positioned vertically above and below each other . similarly , it is important that the perforable diaphragms 96 provided in subassembly 80 be positioned in vertical alignment above and below each other . fig7 schematically illustrates the screen 110 of cathode ray tube monitor normally incorporated in mri equipment 10 with the patient and reference pattern images that are displayed when assist apparatus 12 is properly positioned with respect to equipment cross - sectional imaging plane 16 and plane 16 intersecting the patient p &# 39 ; s body at the anatomical target of interest t . screen 110 specifically displays the leg cross - section images 112 and 114 of v - element 34 , the leg cross - section images 116 and 118 of reference pattern element 36 , the leg cross - section images 120 and 122 of needle - device guide subassembly upper v - reference pattern 92 , and the leg cross - section images 124 and 126 of lower v - reference pattern 94 . if the plane of fiduciary reference patterns 102 and 103 of subassembly 80 is vertical and coincides with equipment cross - section image plane 16 containing target t , cross - section images 128 and 130 of the upper face frame element 86 and cross - section images 132 and 134 of lower face frame element 88 will also appear on the screen as shown in fig7 . fig1 schematically illustrates a remote control push - pull cable end detail that may advantageously incorporated into each of control cables 82 and 84 . basically , each cable end is provided with an affixed scale 150 having indicia in units of measurement corresponding to the units of measurement , usually millimeters , and for the full range of movement of carrier element 66 by cable element 82 in the x - axis direction ( e . g ., 200 millimeters ). only one half of that scale distance ( e . g ., from 0 to 100 millimeters ) is normally used for the movement of open slide element 68 in the z - axis direction by control cable 84 . fig1 schematically illustrates a remote control for push - pull cables 82 and 84 that does not involve manually moving the cable ends . instead an automatic control comprised of control box 160 and electrically connected drive box 180 may be advantageously utilized . control box 160 has display windows 162 and 164 that show the current position co - ordinates of the center of needle - device guide subassembly 80 in their x - axis and z - axis ranges , respectively , display windows 166 and 168 that show the correction required to locate the center of needle - device guide subassembly over the patient anatomical target of interest by operator manual inputs through +( plus ) and -( minus ) respective actuating buttons 170 , 172 , 174 , and 176 . when the proper correction values are found displayed in windows 166 and 168 , start button 178 is manually actuated to start accomplishment of the operator - desired position changes . drive box 180 basically includes two bi - directional conventional stepper motors 182 and 184 that are connected to cable ends 82 and 84 , respectively , through lead screw drive elements 186 and 188 . electrical power inputs to stepper motors 182 and 184 are controlled by control box 160 and cause cable ends 83 and 84 to be thereby advanced or retracted . the fig7 display images are used in the procedures of properly locating and orienting apparatus base member 28 and vectoring the to - be - used medical needle - device during its insertion in guide subassembly 80 and subsequent insertion into the imaged body part of patient p . in fig1 i illustrate assist apparatus 12 in elevation and show a medical needle - device 200 positioned with its lower extreme at the patient anatomical target t . the distance y of that figure can be measured on the screen 110 of the imaging equipment monitor , and corresponds to the actual distance from the line connecting screen images 120 and 122 to target t . scaled distance indicia are normally provided on the exterior of needle - device 200 and extend from the device lower tip upward . that scale information may be easily utilized to determine the depth of insertion of needle - device 200 through guide subassembly 80 and into the patient body - part p from the underside of guide upper open face frame 86 to accurately just reach target t . the procedure for properly aligning apparatus base member 28 is best understood by reference to fig1 and 13 which assume that patient p has been positioned on support table 14 as desired and that assist apparatus 12 has been positioned on the table in proximity to the region of the patient anatomical target of interest . referring to fig1 , the distance designated + x between reference pattern images 112 and 114 is first measured and a millimeter magnitude value ( e . g ., 20 millimeters ) found . the distance - x between reference pattern images 116 and 118 is also measured and a millimeter magnitude value ( e . g ., 10 millimeters ) found . the difference between such measured values ( e . g ., + 10 millimeters ) is a measurement of the magnitude of rotational correction that is required to place base member 28 in a condition where asymmetry axis 43 of double - v reference pattern 30 lies in a plane that can be made parallel to equipment cross - sectional imaging plane 16 . using principles of plane geometry pertaining to double - v reference pattern 30 and elemental mathematics , circular scale 40 marked on base member 28 is provided with measurement units that correspond to the millimeter values of the required correcting rotation . thus , for the assumed fig1 case and with patient support table 14 moved to a position where the physician - user can manually rotate base member 28 , the + 10 value on scale 40 is brought into alignment with indicia 38 to effect the necessary correction . when the base member 28 rotational correction is completed , compression plate subassembly 20 is engaged with support posts 22 , the patient body - part to be subjected to the medical procedure is compressed by downward movement of subassembly 20 to obtain body - part immobility , subassembly 20 is secured against further sliding along post elements 22 , and patient support table 14 , patient p , and assist apparatus 12 are returned to the patient body - part imaging position . reference pattern 30 section images will then appear on display screen 110 with the + x distance between images 112 and 114 being equal to the - x distance between section images 116 and 118 as shown in fig1 . the correlation of scale 40 values to the scaled distances between the leg section images of double - v reference pattern 30 is achieved by virtue of the use of reference pattern &# 34 ; v &# 34 ; configurations wherein the angle included between the legs of each &# 34 ; v &# 34 ; is very nearly equal to the previously - indicated 53 degrees , 8 minutes . the next basic steps to the method of the present invention involve properly positioning needle - device locator subassembly 24 and determining the vector and depth at which the to - be - used medical needle device is to be inserted into needle - device guide subassembly 80 for subsequent insertion into the patient body - part to accurately reach the patient anatomical target of interest . generally , the next step involves taking successive images that in effect move cross - section imaging plane 16 in a z - axis direction until that plane , as viewed on the imaging equipment monitor screen , intersects and contains the patient body - part target of interest t . subsequently and using push - pull cables 82 and 84 from a remote position , the physician user moves both guide carrier element 66 and open slide element 68 to a position where the cross - section images 120 , 122 , 124 , and 126 of v - shape reference patterns 92 and 94 appear on the imaging equipment monitor screen 110 ( see fig7 ), and where a vertical or near - vertical line passing midway between images 120 and 122 and midway between images 124 and 126 intersects the patient target t . if the measured distance between reference pattern images 120 and 122 ( e . g ., 30 millimeters ) equals the distance measured between section images 124 and 126 ( also 30 millimeters ), the to - be - inserted medical - device needle is to be projected through the transparent perforable diaphragms 96 of removable guide subassembly 80 at the centers of the marked transverse lines that numerically correspond to the measured distances ( e . g ., 30 millimeters ) and are so - indicated in the printed marginal scales of face frames 86 and 88 . if the measured distance between section images 120 and 122 ( e . g ., 30 millimeters ) is greater or less than the distance measured between section images 124 and 126 ( e . g ., 25 millimeters or 35 millimeters ), the to - be - inserted medical - device needle is to be projected through the transparent perforable diaphragms 96 of removable guide subassembly 80 at the center of the marked transverse line that numerically corresponds to the measured distance ( e . g ., 30 millimeters ) so - indicated in the printed marginal scale of face frame 86 , and at the center of the marked transverse line that numerically corresponds to the measured distance ( e . g ., 25 millimeters or 35 millimeters ) so - indicated in the printed marginal face frame 88 of needle - device guide subassembly 80 . as a matter of convenience and in cases where the needle - device insertion is not to be centered between the pairs of cross - section images ( where the successive printed &# 34 ; v &# 34 ; apexes are positioned on diaphragm elements 96 ) but instead nearer to one of the two legs or limbs of the v - shape reference pattern , the desired distance of off - set may be measured on monitor screen 110 and implemented by counting the modular lengths that extend along the diaphragm transverse reference lines -- each modular length corresponding to the unit distance between adjacent transverse lines ( e . g ., 5 millimeters ).
apparatus is disclosed for assisting in the location , vectoring , and insertion of a needle - like medical device relative to a patient &# 39 ; s body using medical imaging equipment that produces patient cross - sectional images and that has a monitor which displays produced cross - section images . included image - conspicuous , double - v reference patterns are sectioned and displayed at the equipment monitor in a manner readily identifying and quantifying position changes necessary to assure accurate needle - device location , vectoring , and insertion .