Description:
Residents are allocated portions of several months on the Neuroradiology and Head and Neck Radiology boards. A portion of the training is incorporated with the vascular/interventional rotation and the MRI rotation. Dedicated neuroradiology on the Neuro CT board totals two months at UC Irvine Medical Center.
The residents are expected to protocol all the patients in order to fully determine the clinical indications for each examination. Following adequate clinical information, a decision needs to be made regarding appropriate imaging planes, the slice thickness and slice intervals.
Goals:
- To develop an understanding of neuroimaging of the brain, head and neck, and spine.
- To be able to develop indications for CT vs. MRI studies (see attached Imaging Guidelines: Neuroradiology and MRI).
- To be able to interpret the studies appropriately.
Responsibilities:
- Reporting of the neuro/CT and the head and neck radiology cases, within one day after the cases are performed.
- Being available from 7:30 a.m. to protocol forms that have been received since the previous day. At the end of each day, Monday-Friday, the next day’s exams are previewed and protocoled as needed.
- The resident is to be available promptly for all contrast injections, if needed. This includes the first case of each morning.
- The resident is expected to work closely with the non-radiology housestaff and attending staff to communicate patient needs.
- The following protocols apply for deciding the correct examination:
- The routine brain study is done in the “EMI” plane (20? to the infraborbital-meatal line – Reid’s base line).
- Refer to previous examinations when available. Comparison studies should be performed in a similar fashion regarding positioning and contrast material use.
- Elderly patients, patients with airway problems, patients with rigid spines, sedated children and others may have to be scanned in a plane closer to the axial plane because of mechanical or other reasons.
- Be specific in categorizing various studies properly. Physicians will then learn to request them precisely. Examples:
- Orbital CT – should be done in axial and coronal planes.
- Skull base or facial CT – preferably in two planes.
- Neck CT – axial.
- Spinal CT – usually regional of cervical, thoracic or lumbar areas in axial plane.
- CT myelography – usually regional and with nonionic contrast medium.
- Overlapping sections. Examples:
- Whenever necessary, to compensate for the partial volume effect of scan voxel thickness. (Is the abnormality real?).
- For all orbital studies (usually 2 mm of overlapping through orbital center with EMI or 2.5-5 mm through orbital center with G.E.). In the coronal plane, 5 mm of overlap should suffice.
- The following guidelines are suggested for deciding about ionic contrast material:
- A history to suggest possible risk of contrast material injection should always be obtained in each patient.
- Contrast material should probably not be injected without special deliberation and/or consent in the following patients:
- Anaphyllactoid reaction to contrast material in the past.
- Obviously dehydrated patients (poor skin turgor, sunken eyes, and impaired oral intake).
- Multiple myeloma.
- Gout or uric acidemia.
- Renal failure.
- Insulin dependent, poorly controlled or long-standing diabetes (especially when possibly dehydrated).
- Congestive heart failure.
- Dosage in children should best be kept to 1 cc per pound of body weight. (In small adults it is also best to adhere to this dosage).
- Contrast scans should not be done on the same day as other contrasted radiographic exams – IVU, angiography, etc.
- A decision for contrast injection should be made more readily in patients who have been administered general anesthesia in order to avoid having to repeat the anesthetic to complete the study.
- Contrast injection may be eliminated in the following examination:
- The first study following head trauma if performed within five days of the event.
- Studies to follow ventricular size in unshunted patients.
- Studies to follow ventricular size in shunted patients where the shunt is felt to be functioning satisfactorily.
- Contrast material should be used in shunted hydrocephalus where the shunting system is suspected to be impaired (may show ventriculitis, meningitis).
Reading List
- Connors III JJ and Wojak JC. Interventional Radiology: Strategies and Practical Techniques. Philadelphia: WB Saunders Co., 1999.
- Greenberg JO. Neuroimaging. A Comparison to Adams and Victor’s Principles of Neurology. New York: McGraw-Hill, Inc., 1995.
- JR, da Costa Leite C. Neurodiagnostic Imaging. Pattern Analysis and Differential Diagnosis. Philadelphia: Lippincott-Raven, 1998.
- Newton TH, Hasso AN and Dillon WP. Computed Tomography of the Head and Neck., Volume III. New York: Raven Press, 1988.
- Orrison Jr WW, Lewine JD, Sanders JA, Hartshorne MF. Functional Brain Imaging. St. Louis: C.V. Mosby Co., 1995.
- Phelps PD and Lloyd GAS. Radiology of the Ear. Boston: Blackly Scientific Publications, 1983.
- Ramsey RG. Neuroradiology with Computed Tomography. Philadelphia: W.B. Saunders Co., 1981.
- Som PM and Bergeron RT. Head and Neck Imaging. St. Louis, Mosby Year Book, 2nd ed., 1991.
- Weinberg PE, et al. Neuroradiology Test and Syllabus, Part 1. ACR, 1990.
- Weinberg PE, et al. Neuroradiology Test and Syllabus, Part 2. ACR, 1990.
- Williams AL and Haughton VM. Cranial Computed Tomography. St. Louis: CV Mosby Co.,Inc., 1985.
Neuroradiology and MRI
Anton N. Hasso, M.D., F.A.C.R.
Head and Brain
Computed Tomography (CT)
CT without contrast is the best way to evaluate acute trauma and suspected acute hemorrhage or hemorrhagic infarction within the first 12 to 24 hours. Bone artifacts diminish accuracy in the posterior fossa.
Indications:
- Acute head trauma with suspected intracranial bleeding.
- Suspected subarachnoid hemorrhage.
- Suspected hemorrhagic cerebral infarction.
- Contraindications to MRI (aneurysm clips, pacemakers, neurostimulators, cochlear implants, pregnancy).
Magnetic Resonance Imaging (MRI)
MRI is the best way to evaluate the brain when acute hemorrhage is not an issue and if MRI is available and not contraindicated. CT should be obtained in all other circumstances.
Excellent Indications:
- Suspected, but undiagnosed hemorrhage in posterior fossa or brain stem.
- Suspected, non-hemorrhagic cerebral infarction
- dementia, suspected from multiple infarcts.
- Suspected intracerebral aneurysms or arteriovenous malformations.
- Suspected dural sinus thrombosis.
- Suspected brain tumor, including particularly:
- meningiomas
- posterior fossa tumors
- acoustic neuromas
- Suspected intracerebral metastases
- bulky tumors
- tumor seeding of meninges or any intradural locus
- Suspected lymphoma
- Suspected pituitary tumor or lesion
- Suspected intraorbital or visual pathway lesions
- Suspected intracranial infections such as cerebritis, meningitis, when lumbar puncture is not diagnostic, particularly:
- brain abscess
- toxoplasmosis
- Suspected multiple sclerosis. (MRI of the brain is the first choice over evoked responses).
- Suspected multifocal leukoencephalopathy
Poor Indications:
- Headaches
- Tension headaches
- Migraine
- Cluster headaches
- Dizziness
- Vertigo
Head and Neck (Cranial and Extracranial)
Computed Tomography (CT)
CT is the best way to evaluate cortical bone, such as the bony calvarium. It is best for the middle ear, ossicles and cholesteatoma. CT is vastly superior to plain radiographs for the evaluation of large air spaces such as sinuses, mastoids and adjacent bone.
Indications:
- Evaluation of osseous structures.
- Suspected middle ear disorders.
- Suspected disorders of paranasal sinuses or mastoids. (Please note: limited coronal sections are most cost-effective).
- Evaluation of masses of the hypopharynx and larynx.
- Indications for MRI when MRI is contraindicated.
MRI
MRI is the best way to identify and evaluate soft tissue masses with respect to their source of origin, their precise location and extension, and for temporomandibular joint if imaging is necessary.
Indications:
- Staging of head and neck malignancies.
- Evaluation of the extent of thyroid malignancies.
- Evaluation of thyroid or parathyroid masses if neither nuclide scans nor ultrasound is used.
- Evaluation of masses of nasopharynx, parotid or submandibular glands.
- Evaluation of ocular and orbital lesions.
- Evaluation of temporomandibular joint dysfunction.
Contraindications:
Aneurysm clips, pacemakers, neurostimulators, cochlear implants, pregnancy
(Relative contraindication: An uncooperative patient – anesthesia may be required)
Computed Tomography (CT)
CT is useful for the assessment of the spine when MRI is contraindicated or unavailable but is only rarely superior, such as in the evaluation of fractures.
Indications:
- Suspected spinal fracture.
- Suspected spinal stenosis when low back pain is progressive and heaviness after exercise is relieved by rest.
- Indications for MRI when MRI is contraindicated.
MRI
MRI is best for the evaluation of known or possible tumors, including primary bone tumors, skeletal metastases and intradural masses. It can provide a non-invasive, non-radiating serial evaluation of the response to anti-cancer treatment. It is best to show infection such as spondylitis, osteomyelitis, discitis and abscesses. It is best to show the demyelination of multiple sclerosis is the spinal cord in involved and MRI of the brain is negative. It is best to diagnose spinal disc degeneration, distinguish it from facet or spur problems, and to diagnose spinal cord diseases. It eliminates the need for myelography to diagnose metastases and may make it unnecessary prior to disc surgery. It is best for all levels of the spine.
Indications:
- Suspected vertebral, paraspinal or intraspinal metastases or infections.
- Suspected primary bone tumors.
- Suspected multiple sclerosis or spinal cord disease.
- Suspected disc herniation, based on progressive and persistent symptoms of back and leg pain, lasting four to eight weeks without improvement despite treatment including bed rest and medication.
- Radiculopathy of unknown cause.
- Suspected spinal stenosis when low back pain is progressive and heaviness after exercise is relieved by rest.
- Follow-up of treatment for malignancy or infection.
- Evaluation of recurrent symptoms after spinal surgery.
MRI DANGERS – Screening for Patient Safety (Absolute & Relative Contraindications)
The following militate against patient eligibility for MRI (things to ask your patients about before requesting MRI):
- Cardiac pacemakers and other implantable or surface electronic devices (includes pain stimulators and insulin infusors).
- Artificial heart valves (some but not all).
- Cerebral aneurysm clips and other metal vascular clips on the brain.
- Cochlear implants and metal middle ear drainage devices.
- Bullets, shrapnel or metal fragments in the body (depending on location and presence of fibrosis).
- Metal orthopaedic prostheses in the body region under MRI investigation.
- Metal workers, including grinding and welding (may require X-ray of orbital region to exclude intraorbital metallic foreign bodies).
- History of eye injury from metal fragments (may require X-ray of orbital region to exclude intraorbital metallic foreign bodies).
- Pregnancy.