2 The Academy of Veterinary Imaging 2409 Avenue J, Suite C Arlington, TX (800) opt 4
3 IntroductionThis 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 DirectionsIn this presentation select the appropriate button on the home page to see the described information. The forward arrow button will take you to the next topic. The back arrow will take you to the prior topic. The ‘home’ button will take you to the home page, and the ‘i’ button will take you to the title page.You may view the animation of each procedure up to three times before having to reset (exit) the presentation. Select a button with under the procedure you would like to view to run the animation. If there are no more buttons seen, you will need to reset the presentation to view that procedure again. To reset the presentation, either press ‘Escape’ on you computer, or select the appropriate button on the home page.
5 Ultrasound-guided FNA and biopsy techniqueIndicationsMethod details:Rock/slide the probeAccuracyKeep needle inplane of beamProbe orientationAnimalpreparationScreen orientationSuperficial lesionMaterialsDeep lesionReset (exit) programMethodReferences
6 IndicationsThere 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 SplenomegalyFocal nodules or masses anywhereRenal disease sometimes (i.e. renal dysplasia, renal masses, lymphosarcoma suspects)ProstatomegalyFree abdominal fluidCystsLymphadenopathyU/S guided FNA/biopsies generally not done on:Adrenal glandsTransitional cell carcinoma suspect massesChronic renal failure, glomerulonephritis
8 AccuracyCurrently 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 timePIVKA = 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 handling14-G to 18-G core biopsy needlesBard® automatic biopsy needlesOne hand to triggerForward ‘throw” varies from 11 to 22 mmOrder 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 biopsySample preparation and evaluation:Spray aspirates carefully on the slideSmear gently, dry rapidlyView representative slide before submittingPlace core biopsy samples in cassette, pouch or lens paperPick pathologist carefully
13 Probe orientation Reference marker corresponds to left side of screen (seeScreen Orientationslide)ProbeSkinSchematic of theresulting ultrasoundimageSuperficial “lesion”to biopsyDeep “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 lesionto a “reachable” positionSuperficial lesioncan be toward the edgeor in the centerof the beamDeep lesion needsto be lined uptoward the edge ofthe beam
16 Keep needle in the same plane as the beamSee rotated views
17 Keep needle in the same plane as the beam: Rotated views of the probe/beam/biopsy planeNeedle is placed in the plane of the beam
18 Angle to use for a superficial lesion: Aim needle more perpendicular to beamFNA:Core biopsy: