referring now to the figures and fig1 a and 1b in particular , there is shown an exploded view , transducer probe 10 comprising a block - like carrier 12 having a plurality of ultrasonic transducer elements 11 arranged in at least one row on an application surface 14 adapted to be located on the body surface of a patient . the carrier 12 includes a slot 16 extending partly across the application surface 14 between the transducer elements 11 at substantially the longitudinal center of the surface . a wedge - shaped cavity 18 is defined by two pairs of the mutually facing offset tapered walls 20 , 21 , and 22 , 23 opening symmetrically on both sides of an axis extending perpendicular to the application surface 14 , the edges of the slot 16 defining the bottom of the cavity . horizontal surfaces 24 , 25 , respectively , define the offset between the walls 20 , 21 terminating in the slot 16 and the walls 22 , 23 diverging upwardly into the upper surface 13 of the carrier 12 . a cable bore 28 for receiving a cable ( not shown ) for connecting the individual transducer elements 11 to an electric transmitter - receiver section of an ultrasonic diagnostic apparatus ( not shown ) is formed in a convenient surface of the carrier 12 . the carrier 12 further includes a pair of projections 30 as stopper means to engage an adapter 32 , the projections being formed on each of the mutually facing tapered walls 22 , 23 adjoining the horizontal surfaces 24 , 25 . the body of carrier 12 may be , for example , approximately 100 mm long , 60 mm high and 30 mm wide . in a carrier of such dimensions , the width of the wedge - shaped cavity 18 in the upper surface 13 of the carrier is about 70 mm and converges to the slot 16 of about 3 mm . at the horizontal surfaces 24 , 25 , the width of the cavity is about 50 mm between the walls 22 , 23 and about 40 mm between the walls 21 , 22 . the height of the projections 30 is determined to permit the adapter to be slid upwardly a short distance and then removed forwardly while the carrier is held in position by the hand of an operative grasping the area of the lateral inner wall of the carrier above the upper surface of the adapter , for reasons explained hereinafter . the distribution of the transducer elements 11 as shown on the application surface 14 is purely exemplary . in an actual transducer , approximately 120 transducer elements are positioned on the application surface , each element having a width , for example , of about 0 . 6 mm , and arranged at intervals of about 0 . 1 mm . where the slot 16 opens into the approximate center of the application surface the space between the adjacent elements 11 is widened . the adapter 32 is substantially complementary in shape to the wedge - shaped cavity 18 in the carrier 12 so as to be fitted into the cavity and may be made of elastic synthetic resins . the height of the adapter 32 , however , is somewhat less than the height of the cavity 18 , the upper surface of the adapter , when inserted in the cavity , being parallel to the upper surface 13 of the carrier 12 but about half the distance between the horizontal surfaces 24 , 25 and the upper surface 13 , as shown in fig2 a . the adapter 32 includes a cannula guide portion 34 and a carrier engaging portion 36 . the cannula guide portion 34 comprises the lower portion of the adapter 32 between the opposing walls 20 , 21 and the upper portion of the adapter substantially bounded by the diverging projections of the walls 20 , 21 when the adapter is inserted in the carrier . the carrier engaging portion 36 includes the upper portions of the adapter 32 between the horizontal surfaces 24 , 25 and the upper surface 13 extending outwardly from the projections of the walls 20 , 21 . a pair of grooves 38 , 39 having a defined depth is cut into the two diverging surfaces 40 , 41 of the engaging portion 36 complementary to the walls 22 , 23 of the carrier 12 for engaging the projections 30 of the carrier . the outer and inner vertical walls 46a - d of the carrier engaging portion 36 are grooved with horizontal ridges to facilitate handling of the adapter 32 , only the grooves on the outer walls being shown . the adapter 32 is reversible with respect to the carrier 12 , i . e ., the adapter may be inserted into the cavity 18 with either of the lateral walls of the adapter facing the vertical wall 26 of the cavity . cannula guide means may then be formed on each lateral wall of the adapter for use as convenient . as illustrated in fig1 a and fig2 a , the outer lateral wall of the adapter 32 contains a single vertical cannular guide channel 42 , whereas the inner lateral wall ( fig1 ) is formed with a shallow , triangular cavity 44 extending from a wide portion in the top surface of the adapter and converging to a slot ( not shown ) in the bottom edge of the adapter . the channel 42 and the shallow cavity 44 each terminates in a slot ( not shown ) aligned with the slot 16 in the carrier . when the adapter 32 , formed as shown in fig1 is inserted into the cavity 18 , the cavity 44 and the wall 26 of the carrier 12 form a cannula guide path with converging side walls . the surgeon may then selectively position the the cannula in the triangular guide path at any angle within the width of the path . alternatively , the adapter 32 may be reversed from the position shown in fig1 and the channel 42 positioned next to the wall 26 of the carrier 12 . the channel 42 is then closed by the wall 26 and a single conduit 50 , as shown in fig3 a , is formed for guiding a cannula perpendicularly to the application surface 14 . under the invention , a plurality of cannula guide paths may be formed on at least one lateral surface of the adapter . for example , in the embodiment of fig4 a cannula guide adapter 52 is provided with a plurality of cannula guide channels 54a - d extending radially from the bottom to the top of the adapter 52 in place of the triangular space 44 shown in fig1 . the cannula guide adapter 52 may be fitted in the wedge - shaped cavity 18 of the carrier 12 with the channel 42 in front , whereby four guide paths are defined by the channels 54 and the inner lateral wall 26 of the cavity . cannula guide paths at predetermined radial angles from the bottom to the top of the adapter 52 are thus provided . the puncturing cannula is advanced precisely through the selected closed path and inserted into the objective region of the body of the patient . any convenient number of cannula guide paths may be provided on the lateral surfaces of the cannula guide adapter . for example , in fig2 b and 3a three guide paths are shown . now there will be described the operation of the above - mentioned ultrasonic transducer probe . first , the cannula guide adapter 32 or 52 , which has previously been sterilized , is fitted in the wedge - shaped cavity 18 of the carrier 12 with the channel 42 , for example , being in front and the projections 30 defined on the mutually facing tapered walls 22 , 23 of the carrier 12 fitted into the grooves 38 , 39 cut into the side surface 40 , 41 of the cannula guide adapter . the cannula guide adapter is thus securely fitted in the wedge - shaped cavity 18 . the cannula guide slot path or paths are thereby defined by the channels 44 , 48 or 54 of the adapter and the inner lateral wall 26 of the cavity 18 . then the transducer probe 10 is placed on the body surface of the patient corresponding to the region which requires examination or injection of contrast medium by means of a cannula . ultrasonic search signals are transmitted toward the interior of the patient body and echo signals are received from the search signal intercepting acoustic discontinuities . an ultrasonic sectional image of the region is displayed on a display unit of an ultrasonic diagnostic apparatus . thereafter , the puncturing cannula is inserted into a guide path . the displacement of the cannula is then determined from the depth and relative position of the objective region in the patient body , while the operator observes the display of the sectional image . thereupon , the cannula is introduced at a prescribed angle and inserted into the body of the patient . at the same time , an echoic image of the cannula is also displayed on the display unit , whereby the operator can continually observe the state of the cannula . additionally , the entire probe can be removed easily from around the cannula without disturbing the position of the cannula , for any purpose such as the taking of x - ray exposures . with the aid of the corrugated faces 24 , 25 , the adapter can be slid upwardly enough to disengage the projections 30 and removed forwardly from the probe . the carrier of the probe can then be slid along the body of the patient in the opposite direction , leaving the cannula undisturbed . the formation of the guide path or paths between the channels of the adapter and the lateral inner wall of the carrier greatly facilitates the complete removal of the probe from around the emplaced cannula . it is to be understood that the shape of the cannula guide adapter may be modified without departing from the scope or spirit of this invention .
an ultrasonic transducer probe for connection to ultrasonic diagnostic imaging apparatus for guiding a cannula into proper position for insertion into an objective region of the body of a patient under examination comprises a block - like carrier whose application surface is to be brought into contact with the body the carrier having a plurality of transducer elements equidistantly arranged in at least in one row across the application surface of the carrier , and having a wedge - shaped cavity extending laterally across the carrier diverging from a slot dividing the row of transducer elements into the surface opposite the application surface , and a cannula guide adapter dimensioned to fit within the cavity of the carrier detachably , the adapter being selectably reversible in the cavity and having channels in the lateral sides aligned with the slot for forming cannula guide paths radiating outward therefrom when the adapter is fitted into the cavity .