Behaviour of the 2.1-mm (14 G) automated biopsy needle in phantoms.

Abstract

To study the behaviour of the 2.1-mm (14 G) core biopsy needle in targets of different consistencies and to correlate the needle behaviour to lengths of the samples. A series of butter blocks at temperatures of -5 degrees C, -2 degrees C, +1 degrees C, +4 degrees C, +7 degrees C, +10 degrees C, +13 degrees C, +16 degrees C and +19 degrees C simulating lesions of different hardness in human breast, were passed with needles (3 passes at each temperature). Inner needle behaviour was studied both with and without outer cannula effect. At +4 degrees C to +13 degrees C the needle had a curved course, deviated to the side of its tip. At +4 degrees C, the needle was most deviated (range 4, 8, 10 degrees ) and the samples were largest (8, 12, 12 mm). At -5 degrees C to +1 degrees C the needle was bent, the cannula was not triggered and no sample was obtained. At +16 degrees C and +19 degrees C the needle had a straight course and the length of the sample was decreasing. Behaviour of the inner needle as well as the cannula depends on the hardness of the target. Targets of intermediate hardness yield adequate samples when the inner needle takes a curved course deviated toward the tip and get restored by the cannula.