Ch 19: special radiographic procedures

Arthrography

• study of synovial joints & related soft tissue structures, may also use MRI or CT in addition to arthrography
• knee
    * looks at joint capsule, menisci, collateral, cruciate, & other ligaments, contrast into joint capsule
    * indicated with suspected tears, Baker cyst is nontraumatic indicator
    * contraindicated when pt is allergic to iodine contrast & local anesthetics
    * typically use fluoro, have sling to stress joint to see meniscus, lateral & medial stress depending on which meniscus needs to be seen
    * sterile arthrogam tray supplies, exact supplies vary by doctor & facility
    * negative or positive contrast, iodinated media, double contrast studies are common
    * retropatellar, lateral, medial, and anterior needle approaches, aspirate joint fluid - if normal it’s discarded, if not it’s sent to pathology, empty all fluid and inject contrast, flex knee to spread contrast
    * closely collimated fluoro images of meniscus, 20 degrees between exposures with 9 total images of each meniscus, AP & lateral conventional xrays taken
• shoulder
    * shows joint capsule & rotator cuff, long tendon of biceps, articular cartilage
    * indicated with chronic pain & general weakness, suspected rotator cuff tear
    * xray & fluoro used, need arthrogram tray & spinal needle since joint is so deep
    * usually positive contrast or positive and negative combo - double contrast shows specific areas better
    * spinal needle guided with fluoro into joint space, inject small amount of contrast to check location
    * imaging may be done upright or supine, common to use fluoro with spot images as needed, may take images before and after contrast

CT & MRI Arthrography

• iodine contrast for CT & gadolinium for MRI
• after initial fluoro procedure patient is sent to CT or MRI for additional imaging

Biliary duct procedures

• post-op (T tube/delayed) cholangiography
    * done in radiology dept after cholecystectomy to detect residual stones in biliary ducts
    * T tube catheter placed in common bile duct during cholecystectomy - extends to outside body & is clamped off
    * to detect residual stones - may remove any through the catheter, can further investigate structures
    * contraindicated if pt is sensitive to iodine contrast, has acute biliary infection, or elevated BUN and creatinine
    * clinical history taken, pt in gown and NPO minimum 8 hrs prior
    * fluoro during contrast injection, xrays may be taken after, use iodinated media (may be diluted so it doesn’t cover any stones)
    * drain excess bile first into basin (follow standard precautions when handling bile, inject contrast bit by bit, try to avoid air bubbles as they may be mistaken for stones
• endoscopic retrograde cholangiopancreatogram
    * endoscope inserted to visualize organs & structures, often use duodenoscope during ERCP
    * examine biliary & main pancreatic ducts
    * can be diagnostic or therapeutic
    * usually performed by a gastroenterologist
    * indicated for residual calculi or structures in ducts
    * contraindicated if pt is sensitive to contrast, has acute biliary infection, elevated BUN or creatinine, or possible pseudocyst of pancreas
    * clinical history to rule out pancreatitis or pseudocyst
    * NPO minimum 8 hrs prior and NPO minimum 1 hr+ after procedure
    * fluoro during catheter placement and contrast injection, xrays may be taken after
    * use iodinated media, may be diluted so it doesn’t obscure stones
    * physician places endoscope until hepatopancreatic ampulla (ampulla of Vater) is located, catheter inserted into common bile duct and contrast injected

Hysterosalpingography

• shows uterus & uterine tubes
• shows female reproductive tract using contrast, to evaluate patency of uterine tubes, can see outline of any uterine pathology
• indicated for infertility assessment & for suspected intrauterine pathology, for evaluating uterine tubes after tubal ligation or reconstructive surgery
• contraindicated with pregnancy, pelvic inflammatory disease, and active uterine bleeding
• study is performed 7-10 days after onset of menstruation
• may require bowel prep for pt to prevent gas or feces from obscuring anatomy
• pt may be advised to take pain reliever
• empty bladder immediately before exam
• fluoro is used, table that can go into Trendelenburg is a plus, stirrups for table to assist in lithotomy positioning
• tenaculum may be used to hold cervix in place
• positive contrast used, iodine contrast is preferred - does cause pain when injected & may persist for a few hours after procedure, may do fractional injection of contrast
• speculum inserted & vagina & cervix are cleansed, cannula or balloon catheter inserted - inflate end to block off cervix so contrast doesn’t run out
• injection of contrast done slowly - if uterine tubes are open contrast will flow through tubes into peritoneal cavity
• fluoro used, collimated images taken while uterus & uterine tubes are filling, take image when/if contrast flows into peritoneal cavity
• LPO & RPO may be done to see same side uterine tube

Myelography

• largely replaced by MRI & CT
• studies spinal cord & nerve root branches, contrast given into subarachnoid space
• mostly lumbar & cervical areas studied
• indicated when pt symptoms indicate presence of lesion within or protruding into spinal canal - herniated nucleus pulposus is most common indication, tumors, cysts, & bone fragments are other indications
• has the ability to identify multiple lesions
• contraindicated with blood in CSF, arachnoiditis, increased ICP, lumbar puncture within 2 wks prior
• pt usually given sedative/muscle relaxer 1hr prior to exam, sedation depends on doctor
• table for exam should be able to tilt, have shoulder braces & foot rest with ankle restraints, may need grids & cassette holders for horizontal beam images, may use sponges & pillows for positioning
• ideal contrast mixes well with CSF, is easily absorbed, nontoxic, nonreactive, & has good opacity
    * mostly nonionic water-soluble iodinated contrast is used
    * absorption begins 30 min post injection, good opacity up to 1hr post injection
    * good opacity up to 1 hr post injection, after 4-5 hr contrast is hazy, gone after 24 hrs
• dose is generally 9-15 mL
• if puncture is given in cervical region chin should be hyperextended to prevent contrast from going into brain
• contrast given into subarachnoid space
• lumbar puncture performed at L3-L4 and is most common site
    * pt prone with block under abdomen or left lateral with spine flexed
• cervical/cisternal puncture performed at C1-C2 and is plan B site
    * pt erect or prone with head flexed
• during fluoro pt is tilted from erect to Trendelenburg to move contrast around, after fluoro pt may do xrays
• C-spine positions
    * horizontal beam lateral CR to C4/5
    * swimmer’s CR to C7
      * possible anterior obliques added
• T-spine positions
    * right lateral decubitus AP/PA CR to T7
    * left lateral decubitus AP/PA CR to T7
    * right/left lateral vertical beam CR to T7
• L-spine positions
    * semi-erect lateral horizontal beam CR to L3
      * may do obliques & supine AP

CT Myelography

• may be done in conjunction with regular myelography, iodinated contrast used for CT, pt goes to CT for scans after initial myelography

Hip to Ankle long bone measurement

• more common - can assess lower extremities bilaterally, can measure for hardware if indicated
    * 120 inch SID
    * remove shoes & have knees in true AP

Radiographic Skeletal Survey (bone survey)

• series of images over entire skeleton, may focus on specific area of interest, done to evaluate multiple areas

Conventional Tomography

• obtains diagnostic image of a specific layer of tissue or object that’s superimposed by other tissues, blurs structures above & below a certain plane
• exposure angle: total distance xray tube travels during exposure
    * higher angle = thinner slice thickness
• fulcrum: pivot point
• object plane: plane where anatomy is in focus
• structures at the level of pivot point stay in same spot on IR & other structures are blurred due to tube motion, obtain initial scout to determine level of interest
• large structures need thick plane and low angle
• small structures need thin plane and high angle

Digital Tomosynthesis

• digital tomography, less dose than CT and lower cost, like conventional tomography but obtains pulsed xray exposures instead of continuous, data is automatically reconstructed into tomographic sections