Biopsy needle design
A biopsy needle assembly includes a mandrel within a cannula, the needle assembly is fired into a target tissue to obtain a tissue sample using a force source imparting movement to the needle assembly. The mandrel and cannula design, and force source characteristics minimize needle deflection, and allow the needle assembly to excise extended length tissue samples. The mandrel forms tissue retention ridges within a tissue sample region to reduce fragmentation of the tissue sample.
1. An apparatus, comprising:
a cannula, comprising:
a body extending between a first end and a second end, the body having a first side and an opposite second side; and
a leading edge formed by the first end, the leading edge extending along a first plane, the first plane extending between the first side and second side, the first plane forming a leading edge angle between the intersection of the first side and the first plane;
a mandrel, comprising:
a body extending between a first end and a second end along a central longitudinal axis;
a notch formed by the body, the notch forming a bed extending between the first end and the second end;
a first sample region formed by the bed, the first sample region, comprising:
a first plurality of ridges, wherein each of the first plurality of ridges comprises:
a flank extending from the bed toward the mandrel body second end, the flank terminating at a crest; and
a concave slope descending from the crest;
a second sample region formed by the bed, the second sample region comprising:
a second plurality of ridges, wherein each of the second plurality of ridges comprises:
a flank extending from the bed toward the mandrel body second end, the flank terminating in a crest; and
a concave slope descending from the crest;
a deck disposed between the first plurality of ridges and the second plurality of ridges.
2. The apparatus of claim 1 , further comprising:
a cannula force source imparting movement to the cannula; and
wherein the cannula force source imparts a loaded force between 7 lbs. and 11 lbs.
3. The apparatus of claim 2 , wherein the loaded force is 7.32 lbs.
4. The apparatus of claim 2 , wherein the cannula force source imparts between 2 lbs./in and 3.2 lbs./in upon the cannula.
5. The apparatus of claim 1 , further comprising:
a mandrel force source imparting movement to the mandrel; and
wherein the mandrel force source moves the mandrel between 1 mm and 66 mm.
6. The apparatus of claim 5 , wherein the mandrel force source imparts a loaded force between 7 lbs. and 11 lbs.
7. The apparatus of claim 1 , wherein the bed further comprises:
a reverse ridge, the reverse ridge comprising:
a flank extending from the bed toward the first end, the flank terminating at a crest; and
a concave slope descending from the crest.
8. The apparatus of claim 1 , wherein the cannula leading edge angle is between 12 degrees and 20 degrees.
9. The apparatus of claim 1 , wherein the cannula and mandrel are mounted to an actuator.
10. The apparatus of claim 1 , further comprising:
a vet tip point formed by the cannula leading edge, and wherein the vet tip point leading edge angle is 12 degrees;
a trocar point with a first beveled surface formed by the mandrel first end, wherein the first beveled surface forms a first beveled angle between the intersection of the first beveled surface and the central longitudinal axis, wherein the first bevel angel is 15 degrees.
11. The apparatus of claim 1 , further comprising:
a cannula spring imparting movement to the cannula, the cannula spring comprising a loaded force between 7 lbs. and 11 lbs.;
a mandrel spring imparting movement to the mandrel, the mandrel spring comprising a loaded force of between 7 lbs. and 11 lbs.; and
an actuator housing the cannula spring and mandrel spring.
12. The apparatus of claim 11 , wherein the mandrel spring moves the mandrel between 1 mm and 66 mm.
13. The apparatus of claim 1 , further comprising:
a vet tip point formed by the cannula leading edge, and wherein the vet tip point leading edge angle is 20 degrees;
a trocar point with a first beveled surface formed by the mandrel first end, wherein the first beveled surface forms a first beveled angle between the intersection of the first beveled surface and the central longitudinal axis, wherein the first bevel angel is 15 degrees.
14. The apparatus of claim 13 , further comprising:
a cannula spring imparting movement to the cannula, the cannula spring comprising:
a spring rate of 2 lbs./in.; and
a loaded force of 7.32 lbs.;
a mandrel spring imparting movement to the mandrel, the mandrel spring comprising:
a spring rate of 2 lbs./in.; and
a loaded force of 7.32 lbs.;
an actuator housing the cannula spring and mandrel spring.
15. The apparatus of claim 13 , wherein the bed further comprises:
a reverse ridge, the reverse ridge comprising:
a flank extending from the bed toward the first end, the flank terminating at a crest; and
a concave slope descending from the crest.
16. The apparatus of claim 1 , further comprising:
wherein the cannula translates in a first direction; and
a cannula force source imparting movement to the cannula, wherein the cannula includes a momentum between 0.099 kg m/s and 0.256 kg m/s in the first direction.
17. The apparatus of claim 16 , wherein the cannula momentum is between 0.150 kg m/s and 0.217 kg m/s in the first direction.
18. The apparatus of claim 17 , further comprising:
wherein the mandrel translates in the first direction; and
a mandrel force source imparting movement to the mandrel, wherein the mandrel includes a momentum between 0.120 kg m/s and 0.282 kg m/s in the first direction.
19. The apparatus of claim 18 , wherein the mandrel momentum is between 0.165 kg m/s and 0.239 kg m/s in the first direction.
20. The apparatus of claim 1 , further comprising:
a cannula spring imparting movement to the cannula, the cannula spring comprising:
a spring rate of 2 lbs./in.; and
a preload of 2.5 lbs.
21. The apparatus of claim 1 , wherein the first sample region extends between the bed at the mandrel body first end toward the mandrel body second end.
22. The apparatus of claim 21 , wherein the first sample region extends 20 mm.