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MYELOGRAPHY and CNS Exams using MRI & CT Spring 2012 Meninges Membranes that enclose the brain and spinal cord Dura Mater- outer layer Arachnoid = middle layer Pia mater = innermost layer Subarachnoid space = wide space between arachnoid and pia mater Subarachnoid space Wide space between arachnoid and pia mater Filled with CSF Bathes brain & spinal cord with nutrients Cushions against shocks and blows Where contrast is injected for myelograms CSF Information Total adult CSF volume is 150 ml 50% intracranial 50% spinal Adult opening pressure is normally 7-15 cm fluid >18 abnormal Young adults slightly higher <18-20 Spinal Cord Diameter AP diameter is 7mm through C7 C7 to conus medullaris is 6mm At conus it is 7mm Cord size is considered abnormal if it is over 8mm or under 6mm Myelography General term applied to the radiologic examination of the CNS structures situated in the vertebral canal Requires contrast introduction into the subarachnoid space by spinal puncture Puncture made at L2-L3 or L3-L4 space May also be introduced into cisterna magna at C1 and occipital bone Myelography Contrast is generally water-soluble, nonionic, iodinated medium OMNIPAQUE http://www.ismp.org/newsletters/acutecare/artic les/20031127.asp ISOVUE Contrast Precautions Verify it is the correct contrast Non-ionic iodinated contrast Omnipaque or Isovue Correct concentration 180 and 300 common Check expiration date Keep contrast vial in room until procedure is complete Puncture made at L2-L3 or L3-L4 space and Cisterna Magna Spinal needle injection MYELOGRAM WITH CONTRAST Room should be prepared by RT before patient arrival Table and equipment cleaned Footboard and shoulder supports attached Radiographic equipment checked Image intensifier locked to prevent accidental contact with sterile field or spinal needle Tray setup FOOT BOARD SHOULDER PADS Hand grips MYELOGRAM TRAY Additional items Blankets Sterile towels Sodium bicarbonate (if not in tray) Non-ionic iodinated contrast media Sterile gloves for DR Shields for PT, DR, anyone else in room, and yourself Varying sizes of spinal needles and needles Extra syringes and tubing Cleaning liquid Syringes and Spinal Needles Syringes Spinal Needles (covered) More Spinal Needles (uncovered) PRE- Procedure :Myelography Premedication rarely needed Patient should be well hydrated Check orders, obtain history, labs results (if necessary), and previous exams Informed consent: Risks, benefits alternatives Procedural details, including table movement and sensations should be explained, and get pt into a gown Contraindications and Considerations PT < 15.0 seconds Platelets >100,000 If below 50,000 a platelet transfusion may be indicated before procedure Heparin stopped 4 hours before Preferable to reschedule exam if below 15 Can be restarted 2 hrs after procedure Usually given as IP Coumadin stopped 3-4 days before Usually OP Labs usually indicated Radiation Safety Have shields for PT’s, DR and yourself Question LMP and the possibility of being pregnant Use cardinal rules Time Distance Shielding ALARA Use pulse if possible Save the last image on screen when possible Prone & Lateral Flexion Prone Pillow under abdomen for flexion of spine Lateral flexion is not commonly used Widens interspace for easier introduction of needle Scout Images Cross table lateral With grid Closely collimated Myelography Local anesthesia given at puncture site Lidocaine and sodium bicarbonate Spinal needle inserted (pressure obtained) CSF usually withdrawn and sent to laboratory Contrast injected and needle removed 9-12 ml Table angle and gravity used to move contrast under fluoroscopy Spot images taken as needed Spot Films Central ray vertical or horizontal using CR or film screen cassettes Images are taken at Site of blockage Level of distortion If conus medullaris is area of concern: Lay pt supine Central ray at T12- L1 Use 10x12 cassette and collimate tightly Myelogram overview Myelography If contrast is moved into cervical area, head is positioned in acute extension to prevent contrast from entering ventricular system Acute extension compresses cisterna magna and is the only position that will prevent contrast from entering ventricles Myelography Usually performed as outpatient basis Common for CT myelography (CTM) to be used with conventional Myelogram MRI often used instead Myelography and CTM still used for patients with contraindications for MRI Pacemakers and metal fusion rods Post procedure: Myelography Monitoring required Head and shoulders elevated 30 to 45 degrees Bed rest for several hours Fluid encouraged Puncture site checked before release Possible Complications from Myelography Vomiting Spinal Headache Due to loss of CSF during puncture Increased severity upright Decreased pain when recumbent. Vertigo Neck Pain More Severe Complications Nerve root damage Meningitis Epidural abscess Contrast reaction (anaphylactic shock) CSF leak Hemorrhage Treatment for Spinal Headache Initial treatment Persistent headache Tylenol If a fever occurs, contact MD Horizontal position Forced fluids Beyond 48 hrs w/o fever (24 hrs if severe) May be indicative of meningitis Caffeine Blood patch Blood Patch Sterily injecting a small amount of patient’s blood into the epidural space Clot will occur over hole Usually will stop headache immediately 1st patch is 70% effective 2nd patch is 95% effective Myelogram radiographs Myelograms Images CTM Performed after intrathecal injection Can be performed at any level of vertebral column Multiple slices taken (1.5 – 3mm) Gantry is tilted Windowing allows for density and contrast changes Can obtain images with small amounts of contrast Can be done 4 hours after initial injection CTM MRI of Spinal Cord and CSF flow Non-invasive Provides anatomic detail of brain, spinal cord, intravertebral disc spaces, and CSF within subarachnoid space Does not require intrathecal injection Does not have bone artifacts MRI basics T1 & T2 images can be taken Head coil for brain Body coil and surface coil form spine IV contrast can be used to enhance tumor Gadolinium Contraindications to MRI Pacemakers Ferromagnetic aneurysm clips Metallic spinal fusion rods Myelography Using MRI and Conventional methods MYELOGRAM Preference of MRI MRI is the preferred modality for middle and posterior cranial fossa of brain. In CT these structures are obscured by bone artifacts Spinal cord Allows direct visualization of spinal cord, nerve roots, and surrounding CSF Can be done in various planes Aid in diagnosis and treatment of neurodisorders Usefulness of MRI Assessing demyelinating disease Such as MS Spinal cord compression Postradiation therapy changes of spinal cord tumors Herniated disks Congenital abnormalities of vertebral column Metastatic disease Paraspinal masses MRI and Brain imaging Middle and posterior fossa abnormalities Acoustic neuromas Pituitary Tumors Primary and metastatic neoplasms Hydrocephalus AVM’s Brain atrophy Not valuable for diagnosing: Osseous bone abnormalities of skull Intracerebral hematomas Subarachnoid Hemorrhage CT preferred for these 3 illnesses CT of Brain basics Useful for demonstrating size, location and configuration of mass lesions and surrounding edema Assessing cerebral ventricle or cortical sulcus enlargement Shifting of midline structures caused by mass lesions, cerebral edema, or hematoma Indications for Pre and Post contrast Imaging using CT Suspected Neoplasms Suspected metastatic disease Arteriovenous malformation (AVM) Demyelinating disease (MS) Seizure disorder Bilateral isodense hematomas Indications for Brain scans without Contrast media Dementia Craniocerebral trauma Hydrocephalus Acute infarcts Post evacuation follow up of hematomas CT Brain imaging Most often Axial orientation Gantry 20-25 degrees to OML Allows lowest slice to provide an image of both the upper cervical, foramen magnum, and roof of orbit 12-14 slices 8-10 mm slices 3-5 mm slices through post fossa Depending of PT size Slice thickness CT Brain imaging (cont) Coronal imaging Helpful in evaluation of Pituitary gland Sella turcica Facial bones Sinuses CT: Modality of choice Modality of choice for the following” Hematomas Suspected aneurysms Ischemic or hemorrhagic strokes Acute infarcts Used as initial diagnostic modality for: Craniocerebral trauma CT of Spine Useful in diagnosis of vertebral column hemangiomas and lumbar spine stenosis Often used post-trauma to assess Axis and Atlas fractures and for better demonstration of C7-T1 Clearly demonstrates size, number and locations of fracture fragments of C, T and L spine. Surgery Applications of CT imaging Greatly assists surgeons in distinguishing neural compression by soft tissue from compression by bone Post-op Useful in assessing outcome of surgical procedure MRI vs. CT MRi superior to CT for imaging of posterior fossa CT has artifacts from bone MRI is free from bone artifacts MRI has inability to image calcified structures. CT is superior for calcifications MRI can detect cerebral infarction earlier than CT. Both modalities provide similar information on subacute and chronic strokes Diskography and Nucleography Radiologic exam of individual intervertebral disks Small amount of water soluble iodinated contrast injected into center of disk double needle entry Pt’s given local anesthetic Used to investigate disk lesions So pt is alert and communicate with DR about pain when needle and contrast are inserted Ruptured nucleus pulpous Has been largely replaced by CTM and MRI Diskograms Lumbar Diskograms Vertebroplasty Interventional radiology procedure to treat compression fractures or other pathologies in the vertebral bodies Used when conservative treatment does not work Used when severe pain does not improve over a number of weeks of treatment Percutaneous Vertebroplasty Done in specials or OR Trocar needle is advanced through pedicle into the vertebral body under fluoro Non-ionic contrast media is used to confirm needle placement Bone cement ( polymethyl methacrylate) is injected into vertebral body using fluoro AP & LAT images taken post procedure CT sometimes done as well Vertebroplasty under Fluoro Post Vertebroplasty Percutaneous Kyphoplasty Trocar needle advanced Through pedicle, avoiding spinal canal Biopsies can be taken Balloon catheter used to expand the compressed vertebral body to near its original height before injection of bone cement Trocar needle is considered the “working cannula” Kyphoplasty Outline Pre and Post Kyphoplasty radiographs Complications of Vertebroplasty and Kyphoplasty Most common: leakage of cement Less common: pulmonary embolism Death Success of Vertebroplasty and Kyphoplasty Success is measured by the pt’s pain reduction and quality of life improvement Can help reduce hunchback and restore normal curvature With Kyphoplasty there is a 80-90% success rate Pain Management Epidural Injection Facet Injection Spinal Cord stimulation Radiofrequency Neurolysis Considerations of Pain Management Interventional Procedures Stop NSAID 3 days prior to procedures With Facet injections no pain relievers 4 hours prior to procedure Takes 3- 10 days for full results to manifest Done when conventional treatment has not helped Epidural Used to treat pain as a result of and injured disk affecting spinal nerves Done under fluoroscopy with PT awake Decreased inflammation & swelling Takes 10- 15 minutes Recovery short Sterile procedure Complications Spinal headache (most common) Infection Epidural Hematoma Can be done at any level of the spine Place a needle (often with catheter) into epidural space Small amount of contrast injected to verify placement Corticosteroid & anesthetic injected ( Cortisone Lidocaine Epidural Epidural with Catheters Facet Injections Indications: Diagnosis Therapy Causes of pain include: Inflammation, swelling, or arthritis Awake under fluoro Takes 20-40 minutes Sterile procedure Complications Pain at site Bleeding Infection Increase in pain Facet Injections Inject needle into facet joint Inject contrast to verify needle placement Inject lidocaine or bupivivaine (anesthetic) & corticsteroid (antiinflammatory) Side effects of Steroids Fluid retention Weight gain Mood swings Increase in blood pressure Usually temporary Spinal Cord Stimulation Delivers low voltage electrical stimulation to the spinal cord Delivered through 1-2 wires which are carefully placed in epidural space Electrical signals replace sensation of pain with a tingling sensation Done in two stages Trial Permanent placement SCS Radiographs Trial and Permanent Placement Done in OR If trial period helps permanent generator is placed under skin in OR Contains generator with battery (some are rechargeable) Local anesthetic & intravenous sedation Wires placed in epidural space PT goes home with wires in place for 1 week to test and see if it helps Periodically battery is replaced Others have transmitters & generators Generators only vs. Generators with Transmitters SCS with generators inside the body must be replaced in OR Some are one time use Those that are rechargeable allow for more time in between battery replacement SCS with transmitters can also be one time use or rechargeable PT can adjust settings according to different programs Set by DR according to PT’s pain patterns SCS With Generator and Transmitter SCS Indications, Benefits & Risks Indications: Chronic pain associated with: Neuropathic pain Failed back surgery syndrome Arachnoiditis Certain vascular disease Benefits Reduces rather than eliminates pain Reduces pain by 50% Reduces narcotic use Risks Infection & bleeding Paint at insertion site Nerve injury Dural puncture or tear Migration or breakage of wire Radiofrequency Neurolysis Uses high frequency radio waves to produce a heat lesion Lesion ablates or inactivates nerves responsible for transmitting pain Usually done in L and C spine Pain can be caused from whiplash or arthritis Done under fluoro in OR Radiofrequency Neurolysis Helps for 6-24 months 70% of PT’s get relief Takes about 45-60 minutes Can be repeated if pain returns Radiofrequency Neurolysis PT is awake and mildly sedated Local anesthetic injected Stimulation test is done to verify needle placement PT is questioned for tingling or buzzing feeling (as when hitting your funny bone) Once PT confirms this , they are sedated more Radio waves are transmitted ablating the nerve Muscles may spasm or “jump” RF Risks Infection Bleeding Blood vessel damage Soreness for a few days