Abstract
Purpose: 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.
Material and Methods: A series of butter blocks at temperatures of -5 °C, -2 °C, +1 °C, +4 °C, +7 °C, +10 °C, +13 °C, +16 °C and +19 °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.
Results: At +4 °C to +13 °C the needle had a curved course, deviated to the side of its tip. At +4 °C, the needle was most deviated (range 4, 8, 10 °) and the samples were largest (8, 12, 12 mm). At -5 °C to +1 °C the needle was bent, the cannula was not triggered and no sample was obtained. At +16 °C and +19 °C the needle had a straight course and the length of the sample was decreasing.
Conclusion: 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.