Welcome to the clinical refresher for myelography. This module was written by Vicki Sanders, MSRS, RRA, RTR, CV, CT. After completing this module, you will be able to identify the indications, contraindications, and complications of myelography. Explain pre-procedure preparation and assessment for myelography.
Apply radiation protection and technical factors for myelography. List equipment and contrast materials used in myelography. Describe the patient positioning and step-by-step procedure to perform cervical, thoracic, and lumbar myelography.
Discuss post-procedure care and instructions for patients after myelography. Before the procedure, patients should be evaluated and have the procedure cleared by a physician. Ensure the patient is well hydrated before the procedure. The patient should have nothing by mouth for 4 to 6 hours before the procedure, and any medications which decrease seizure threshold should be evaluated by a physician. These medications may need to be withheld 48 hours before the procedure and for 24 hours after the procedure.
Before beginning the procedure, a brief history from the patient should be recorded. This history should include at least the patient's current medications, allergies, and pregnancy status, as well as the specific nature of their symptoms, any previous spinal surgeries, and any history of seizures. Additionally, before the procedure, the patient's previous studies should be reviewed, and as well as orders for any laboratory testing of CSF samples.
the patient's opening and closing pressure, and the amount of fluid to be removed. A focused neurological examination may also be performed. Informed consent must be obtained from the patient or surrogate before the procedure and should include the purpose and nature of the procedure, the performance of the procedure, the risks, complications, and expected benefits of the procedure, the risks of not accepting the procedure, any reasonable alternatives to the procedure, and the most likely risks and benefits of those alternatives, and the patient's right to refuse the procedure.
Patients should have the opportunity to ask questions, and all of their questions must be answered. Risks of myelography include post-procedure spinal headache, infection, bleeding, seizures, cerebral herniation, local and radicular pain, local nerve root trauma, Possible extraarachnoid injection, numbness, epidermoid tumor or cyst formation, and abducens nerve palsy. Patients must be able to understand these risks at the time they give consent. The patient's surrogate or power of attorney should be contacted to provide consent for patients under the influence of medications or experiencing altered mental capacity.
To be able to safely tilt the patient during myelography, a tilting fluoroscopy table with proper support devices and physical ankle restraints is necessary. The ability to manipulate the table is key to moving the injected contrast into the correct position for imaging. Pulsed fluoroscopy and last image hold, or LIH, functions are useful in decreasing radiation dose to the patient.
Reducing pulsed fluoroscopy to 7.5 pulses per second and reducing filming rate to one exposure per second greatly reduces radiation exposure to patients and others in the room. LIH allows the user to save the current image on the monitor without using an additional exposure to take a spot image. Images and fluoroscopic field of view, or FOV, are manually collimated as much as possible to limit radiation exposure to the patient.
The detector is placed as close to the patient as safely possible to reduce magnification and patient dose. Automatic dose rate controls and automatic brightness controls automatically adjust the kilovoltage peak, or KVP, and milliampereage, or MA, to achieve a dose as low as reasonably achievable. Selecting the correct patient procedure and patient size on the fluoroscope will ensure the KVP and MA settings will be appropriate for the procedure being performed.
The use of magnification increases spatial resolution, but also increases the radiation dose to the patient, and should be used sparingly during the procedure. The total time the beam is on should be limited as much as possible by using intermittent fluoroscopy, LIH, and pulsed fluoroscopy. All personnel and family in the examination room are required to wear radiation safety equipment, including lead aprons and thyroid shields.
If the fluoroscope being used has a lead protective curtain, it should be removed so it will not interfere with the integrity of the sterile field. The bucky slot cover is engaged to reduce exposure to the staff and others. The hands of the operator should be kept out of the fluoroscopic FOV as much as possible, or sterile lead gloves should be used to reduce dose.
Preliminary scout images of the spine are obtained before the procedure begins. Most of the equipment required for the procedure is included on the lumbar puncture or myelogram tray, though the contents of the tray may vary slightly by vendor and facility standardization. The equipment includes lidocaine 1% without epinephrine, two 18-gauge needles or 18-gauge filter needles which are used to drop lidocaine and contrast, and one 25-gauge 1.5-inch needle for local infiltration. There is a manometer, a three-way stopcock, and four plastic tubes with caps numbered 1 through 4. There will be several 10 milliliter syringes for lidocaine and several 20 milliliter syringes for contrast, as well as several pads of 4x4 or 2x2 inch gauze.
There will be a sterile fenestrated drape, at least three sponge applicators, plastic extension tubing, and a small bandage. The procedure will also need antiseptic solution, such as providone iodine, or at least three antiseptic solution swabs. Chlorhexadrine gluconate, also known as Chloroprep, is contraindicated for procedures which may have contact with the meninges.
Refer to facility policy for use of chlorhexadrine. The procedure requires sterile gloves, a metallic hemostat or instrument to localize the entry site, and an indelible marker. A 22 or 25 gauge, 3.5 inch atraumatic or pencil point spinal needle.
or a 22 or 25 gauge, 3 inch bevel tip spinal needle can be used. Use of bevel tip needles may increase the incidence of post-dural puncture headache. Obese patients may require a longer needle. Optionally, silk or medical tape may be used to secure the gown to the patient. Lastly, the procedure requires 6 to 12.5 milliliters of non-ionic water-soluble contrast media specifically indicated for intrathecal use.
Iohexol and iopamidol are approved for intrathecal injection. Dose and concentration are dependent on the area being examined. Total dose should not exceed 3,060 milligrams of iodine.
The total concentration should not exceed 300 mg iodine per milliliter for adults. Ionic contrast is absolutely contraindicated for intrathecal administration due to the risk of seizures and other serious complications. Always double-check the contrast to ensure it is non-ionic.
The myelogram procedure is tailored to the individual patient, determined by their clinical condition and history. The procedure should be explained to the patient in advance to ensure maximum patient cooperation with instructions. Needle placement and any observed abnormalities should be documented and recorded with spot films or with last image hold.
To inject the contrast, begin a lumbar puncture as normal with the spinal needle. Once the subarachnoid space has been reached, cerebral spinal fluid will begin to flow out the needle. Attach the contrast syringe with connection tubing to the spinal needle with a wet connection by allowing a drop of contrast material to enter the hub of the spinal needle. Tilt the table approximately 15 degrees upright to keep the contrast in the lower lumbar area.
Over 1 to 2 minutes, slowly instill the non-ionic, water-soluble contrast media under intermittent fluoroscopic guidance. Contrast should flow away from the needle and begin to mix with the CSF. Obtain a spot image to document needle placement. After injection, disconnect the connection tubing.
Replace the stylet fully and remove the needle. Clean the antiseptic solution from the patient's skin and place a small bandage at the entry site. Secure the patient to the tabletop using the tabletop support devices.
After injecting contrast, begin a cervical myelogram by hyperextending the patient's head and placing their chin on a chin rest to create a trough in the lordotic curve. This position also helps prevent rapid ascension of the contrast into the basal cisterns. Ensure patient support devices are properly engaged, then slowly tilt the table into a Trendelenburg position while observing the column of contrast moving into the cervical area.
Once contrast reaches the proper area, return the table to a horizontal position. Obtain posterior anterior or PA images, left and right oblique views at approximately 30 and 55 degrees from the tabletop, and cross-table lateral images. A cross-table lateral swimmer's view often is performed as well to better visualize the cervical thoracic junction in patients with broad shoulders.
Images can be obtained either by digital fluoroscopy, routine imaging techniques, or a combination of both. After injecting contrast, begin a thoracic myelogram by rolling the patient into a lateral or supine position, with the patient's head elevated on a pillow. Slowly tilt the table into a Trendelenburg position while observing the column of contrast moving into the thoracic area.
Once the contrast reaches the proper area, return the table to a horizontal position. At minimum, AP and lateral views of the thoracic region are performed. Both obliques can be performed along with a lateral swimmer's view if necessary.
Images can be obtained either by digital fluoroscopy, routine imaging techniques, or a combination of both. After injecting contrast, begin a lumbar myelogram by confirming the column of contrast has spread throughout the lumbar region. Obtain posterior anterior, or PA, images, both obliques, and cross-table lateral images. Standing flexion and extension views may also be performed.
Images can be obtained either by digital fluoroscopy, routine imaging techniques, or a combination of both. After fluoroscopic or conventional images are obtained, the patient is moved to a stretcher. Avoid abrupt or active patient movement.
Instruct the patient to remain passive and move the patient slowly to the stretcher. The patient is then transported to CT by stretcher for sectional imaging. Post-procedure cropping, shuttering, electronic collimation or electronic masking that eliminates anatomical information is not acceptable practice for radiographers. Post-exposure shuttering, cropping, and other methods may be used to eliminate large regions of brightness so long as it does not eliminate any anatomical information.
Any necessary annotations can be made on images and stored. It is best practice to use lead markers to indicate the side of the patient during the examination. To evaluate the quality of a myelogram, verify that the appropriate level of spinal column with contrast medium present is demonstrated on the finished images.
The patient's images and CT results should be reviewed by the radiologist to ensure the area is properly opacified with contrast. The patient's position may need to be manipulated to ensure the contrast is in the proper area for sectional imaging. Every attempt should be made to resolve any questionable findings before the patient is discharged to avoid repeated procedures.
Collimation should be evident on still images and images of the conus should be included in lumbar myelography. Images of the C7 to T1 junction should be included in cervical myelograms. This concludes the clinical refresher for myelography. You should not...