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Disc Aspiration/Biopsy | Radiology Key

Disc Aspiration/Biopsy



Disc Aspiration/Biopsy


Donald V. La Barge, III, MD










Graphic shows narrowing of intervertebral disc space and purulent material throughout disc space extending ventrally and dorsally image into the epidural space. Note the destructive endplate changes image.






Graphic shows bone image and disc image destruction with paraspinal image and epidural image involvement in a representation of granulomatous discitis/osteomyelitis. Note the intraosseous abscesses image.


TERMINOLOGY


Abbreviations



  • Fine needle aspiration (FNA)


Definitions



  • Fine needle aspiration/core biopsy of intervertebral disc material ± vertebral endplate


PRE-PROCEDURE


Indications



  • Suspected osteomyelitis/discitis



    • To identify infectious organism


Contraindications



  • Coagulopathy


  • Inability to tolerate prolonged prone positioning


Getting Started



  • Things to check



    • Laboratory data



      • Coagulopathy/anticoagulation studies



        • Prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR)


        • Hemoglobin, hematocrit, and platelet count


        • Bleeding time


      • Infection/inflammatory markers



        • White blood cell count, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)


        • Temperature


      • Positive cultures?



        • Blood, urine, respiratory, cerebrospinal fluid (CSF)


    • Imaging studies



      • Look for most accessible site if multiple sites of abnormality


      • Evaluate anatomy


      • Are imaging findings consistent with discitis/ osteomyelitis?



        • Loss of disc height with increased T2-weighted signal and enhancement of disc


        • Decreased T1- and increased T2-weighted MR signal associated with vertebral endplate destructive changes above and below disc


        • Paraspinal &/or epidural inflammatory changes ± abscess


    • Clinical presentation/history



      • Is patient taking antibiotics?


      • Anticoagulation/antiplatelet therapy?


      • Any recent surgery or procedure that may be source of infection?


    • Informed consent


  • Medications



    • Local anesthetic


  • Equipment list



    • Standard sterile prep and drape materials


    • Radiopaque marking device



      • Always carefully ensure appropriate level, especially with subtle radiographic changes


    • Local anesthetic



      • 5 mL syringe


      • Buffered 2% lidocaine


      • Long 25-gauge needle


    • Needle for FNA/biopsy



      • May choose 22-25-gauge Chiba needle for FNA



        • Smaller gauge needle may be inadequate in setting of tenacious, purulent material


      • Larger gauge system preferred if doing biopsy (e.g., 13-16-gauge)


    • Specimen containers



      • Formalin vs. saline for tissue samples, depending on pathology suspected/institution protocol



        • Formalin for cytology in cases of suspected tumor


        • Nonbacteriostatic saline for suspected infection


        • Consult with pathology/laboratory department regarding individual institutional protocol


    • Bandage


PROCEDURE


Patient Position/Location



  • Best procedure approach




    • Prone


  • Imaging modality considerations



    • Fluoroscopy



      • Biplane allows easier triangulation compared with single plane/C-arm



        • Easier to frequently check AP and lateral fluoroscopy to ensure safe needle trajectory


    • CT



      • Preferred for cervical and thoracic discs by many interventionalists



        • Vascular or spinal cord injury more likely in cervical and thoracic region


        • Potential for lung injury (pneumothorax) in thoracic region


      • Ensure renal function/contrast compatibility if intravenous contrast is contemplated



        • BUN/creatinine and glomerular filtration rate should be known


        • Contrast information form should be completed


        • Ensure that patient is not allergic to iodinated contrast


      • CT fluoroscopy generally offers shorter procedure times and lower radiation exposure to patient compared with conventional CT


Equipment Preparation



  • Have local anesthetic prepared


  • Proper specimen containers


  • Ensure FNA &/or biopsy needles are available


Procedure Steps



  • Carefully review pre-procedure imaging and ensure correct level


  • Obtain informed consent


  • Position patient


  • Procedure “time out”



    • Correct patient, level(s), and procedure


    • All necessary equipment available


    • Pathology representative present if desired


  • Begin conscious sedation as indicated


  • Carefully mark proper level(s) for FNA/biopsy



    • Angle AP fluoroscopy tube along expected needle trajectory


    • Approach dorsolaterally, anterior to facet


    • For thoracic and lumbar levels, use “Scotty dog” anatomy



      • Superimpose superior endplate of vertebra below disc to be intervened upon


      • Place “ear” of “Scotty dog” (superior articular process) at center of intervertebral disc by angling AP fluoroscopy plane toward desired side


      • Needle entry should be at junction of middle 1/3 and outer 1/3 of disc (in front of “Scotty dog ear”)


  • Mark skin


  • Perform sterile prep and drape


  • Create skin wheal, and generously apply local anesthetic along expected needle trajectory



    • Spot fluoroscopy of numbing needle is beneficial for trajectory planning



      • Long spinal needle may be necessary for deep application of anesthetic in obese patients


  • Insert FNA/biopsy needle



    • Utilize intermittent fluoroscopy to ensure safe trajectory


    • Check AP and lateral fluoroscopy to triangulate once needle is anchored under skin


    • Obtain spot radiograph to document correct level and successful needle placement


  • If bone encountered, usual culprit is facet



    • Check oblique/lateral fluoroscopy


    • If confirmed to be facet angle anteriorly



      • Often requires withdrawal (1-2 cm) first to allow redirection of needle tip


  • Warn patient when passing near nerve root and prior to puncturing disc



    • May decrease sudden motion in response to pain


  • Advance carefully under fluoroscopic guidance into disc



    • Where to start sampling depends on underlying pathology



      • Generally recommend sampling inflamed portion of disc/endplate such that sample includes nucleus, annulus, and endplate


      • FNA/biopsy of paraspinal inflammation may also increase diagnostic yield


  • FNA



    • Apply small syringe (usually 3-5 mL) to 18-22-gauge Chiba needle, and gently aspirate



    • Place specimen in appropriate container


  • Biopsy



    • e.g., Ostycut (Bard; Helsingborg, Sweden): Remove needle, attach vacuum syringe, lock back, advance biopsy system slowly under fluoroscopy, release suction, withdraw specimen


    • Place specimen in appropriate container


  • After needle removal

Sep 22, 2016 | Posted by in EMERGENCY RADIOLOGY | Comments Off on Disc Aspiration/Biopsy
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