1. Ultrasound-guided fine-needle aspirate and biopsy technique
Copyright © 2010 The Academy of Veterinary Imaging

2. The Academy of Veterinary Imaging
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3. Introduction
This presentation describes the methods to use as well as other factors to consider when performing an ultrasound-guided fine-needle aspirate (FNA) or core biopsy. The scanning planes used for FNA and core biopsy are the same. The technique varies somewhat, and the differences are demonstrated. Animation is used to demonstrate the aspirate/biopsy techniques. Please note that this animation will not run properly with older versions of PowerPoint or PowerPoint viewer.

4. Directions
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5. Ultrasound-guided FNA and biopsy
technique
Indications
Method details:
Rock/slide the probe
Accuracy
Keep needle in
plane of beam
Probe orientation
Animal
preparation
Screen orientation
Superficial lesion
Materials
Deep lesion
Reset (exit) program
Method
References

6. Indications
There are many indications for ultrasound-guided aspirates and biopsies as there are essentially no pathognomonic lesions in ultrasound. Most of the time a cytologic or histopathologic sample is needed to make a definitive diagnosis. Samples for cytology and histopathology may obtained with ultrasound-guided, laparoscopic and surgical procedures.

7. Indications Icterus/liver enzyme elevation/elevated bile acids
Splenomegaly
Focal nodules or masses anywhere
Renal disease sometimes (i.e. renal dysplasia, renal masses, lymphosarcoma suspects)
Prostatomegaly
Free abdominal fluid
Cysts
Lymphadenopathy
U/S guided FNA/biopsies generally not done on:
Adrenal glands
Transitional cell carcinoma suspect masses
Chronic renal failure, glomerulonephritis

8. Accuracy
Currently there is a lack of consensus about the accuracy of ultrasound-guided fine needle aspirates and biopsies compared to surgical or post mortem biopsy sample results. Some studies report high accuracy, others, low accuracy. The differential diagnosis and case presentation both should be considered when determining the best method of obtaining a cytology or histopathology sample.

9. Animal preparation Coagulation concerns:
A physical examination should be done to assess evidence of a coagulopathy, and if one is suspected, no aspirate or biopsy is recommended.
The pre-biopsy hematocrit should be known.
At least a platelet count is recommended before a fine-needle aspirate is done.
Perform a buccal mucosal bleeding time if i.e. von Willebrand’s disease, or other disorders of primary coagulation are suspected.
A platelet count as well as coagulation profile (PT, aPTT and/or PIVKA) are recommended before a core biopsy is done.
Sedation/brief anesthesia may be indicated.
Prepare a sterile field

10. Coagulation tests PT = Prothrombin time
PTT = Partial thromboplastin time
PIVKA = Proteins induced by vitamin K antagonism

11. Materials Biopsy guide or not
22-G 1.5 inch “cysto’ needle or 22-G 3.5 inch spinal needle is often used for fine-needle aspirates.
Attach needle to extension set then syringe for easier handling
14-G to 18-G core biopsy needles
Bard® automatic biopsy needles
One hand to trigger
Forward ‘throw” varies from 11 to 22 mm
Order from Sound Technologies or other distributors

12. Method Biopsy guide or freehand Thickness of beam is 1-2 mm
Must keep needle in plane of beam (biopsy guide would do this for you)
Shortest distance/safest pathway
“Sewing-machine” motion for fine-needle ‘aspirates’
Stab incision in skin before doing a core biopsy
Sample preparation and evaluation:
Spray aspirates carefully on the slide
Smear gently, dry rapidly
View representative slide before submitting
Place core biopsy samples in cassette, pouch or lens paper
Pick pathologist carefully

13. Probe orientation Reference marker corresponds to left side of screen
(see
Screen Orientation
slide)
Probe
Skin
Schematic of the
resulting ultrasound
image
Superficial “lesion”
to biopsy
Deep “lesion”
to biopsy

14. Screen orientation Near field Opposite reference marker
Far field

15. Rock and/or slide the probe to a “reachable” position
to line up the lesion
to a “reachable” position
Superficial lesion
can be toward the edge
or in the center
of the beam
Deep lesion needs
to be lined up
toward the edge of
the beam

16. Keep needle in the same plane
as the beam
See rotated views

17. Keep needle in the same plane as the beam: Rotated views of the
probe/beam/biopsy plane
Needle is placed in the plane of the beam

18. Angle to use for a superficial lesion:
Aim needle more perpendicular to beam
FNA:
Core biopsy:

19. Superficial lesion FNA

20. Superficial lesion FNA

21. Superficial lesion FNA

22. Superficial lesion FNA

23. Superficial lesion FNA

24. Superficial lesion FNA

25. Superficial lesion FNA

26. Superficial lesion FNA

27. Superficial lesion FNA

28. Superficial lesion core biopsy

29. Superficial lesion core biopsy
Take biopsy

30. Superficial lesion core biopsy

31. Superficial lesion core biopsy

32. Superficial lesion core biopsy

33. Superficial lesion core biopsy
Take biopsy

34. Superficial lesion core biopsy

35. Superficial lesion core biopsy

36. Superficial lesion core biopsy

37. Superficial lesion core biopsy
Take biopsy

38. Superficial lesion core biopsy

39. Superficial lesion core biopsy

40. Angle to use for a deep lesion: Aim needle more parallel to beam
FNA:
Core biopsy:

41. Deep lesion FNA

42. Deep lesion FNA

43. Deep lesion FNA

44. Deep lesion FNA

45. Deep lesion FNA

46. Deep lesion FNA

47. Deep lesion FNA

48. Deep lesion FNA

49. Deep lesion FNA

50. Deep lesion
core biopsy

51. Deep lesion core biopsy
Take biopsy

52. Deep lesion
core biopsy

53. Deep lesion
core biopsy

54. Deep lesion
core biopsy

55. Deep lesion
core biopsy

56. Deep lesion core biopsy
Take biopsy

57. Deep lesion
core biopsy

58. Deep lesion
core biopsy

59. Deep lesion
core biopsy

60. Deep lesion
core biopsy

61. Deep lesion core biopsy
Take biopsy

62. Deep lesion
core biopsy

63. Deep lesion
core biopsy

64. Deep lesion
core biopsy

65. References
Fife WD (2005) Abdominal ultrasound: Aspirations and biopsies, In Ettinger SJ, Feldman EC (eds), Textbook of Veterinary Internal Medicine, 6th edition, St. Louis, Elsevier Saunders, pp
Nyland TG, Mattoon JS, Herrgesell EJ, Wisner ER (2002) Ultrasound-guided biopsy, In Nyland TG, Mattoon JS (eds), Small Animal Diagnostic Ultrasound, Philadelphia, WB Saunders, Co., pp