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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.
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Indications Accuracy Materials Animal preparation Ultrasound-guided FNA and biopsy technique Probe orientation Superficial lesion Deep lesion Method Screen orientation References Rock/slide the probe Keep needle in plane of beam Method details: Reset (exit) program
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.
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
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.
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 Willebrands 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.PT, aPTT and/or PIVKA Sedation/brief anesthesia may be indicated. Prepare a sterile field
Coagulation tests PT = Prothrombin time PTT = Partial thromboplastin time PIVKA = Proteins induced by vitamin K antagonism
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
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
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
Reference marker Near field Far field Opposite reference marker Screen orientation
Rock and/or slide the probe to line up the lesion to a reachable position Deep lesion needs to be lined up toward the edge of the beam Superficial lesion can be toward the edge or in the center of the beam
Keep needle in the same plane as the beam See rotated views
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
Angle to use for a superficial lesion: Aim needle more perpendicular to beam FNA: Core biopsy: