sequence: axial with ultra thin slices (e.g.sequence: whole brain axial and sagittal, a volumetric acquisition is preferred when available.SequencesĪ good protocol for this purpose involves at least: The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preference, institutional protocols, patient factors (e.g. NB: This article is intended to outline some general principles of protocol design. 0.2 mL/kg in adults, children and infants.MRI protocol for assessing the posterior fossa, including the cerebellopontine angle, is a group of basic MRI sequences put together to best approach lesions involving the brainstem, cranial nerves (CN III to CN XII), cerebellum and CSF spaces (fourth ventricle, cisterna magna, prepontine cistern, and CPA cisterns). The recommended dose of gadolinium DTPA injection is 0.1 mmol/kg, i.e. Use T1 SE axial and coronal after the administration of IV gadolinium DTPA injection(copy the planning outlined above). T1 pre contrast and post contrast scans are only required in case of tumor present in internal auditory canal. Slices must be sufficient to cover IAMS from the hippocampus up to the line of the C1 vertebral body. An appropriate angle must be given in the sagittal plane (perpendicular to the brain stem). Plan the axial slices on the coronal plane angle the position block parallel to the line along right and left IAMS(as shown in the diagram).Check the positioning block in the other two planes. Slices must be sufficient to cover IAMS from the posterior border of sphenoid sinus up to the line of the fourth ventricle. An appropriate angle must be given in the sagittal plane (parallel to the brain stem). Plan the coronal slices on the axial plane angle the position block parallel to the line along right and left IAMS(as shown in the diagram).Check the positioning block in the other two planes. An appropriate angle must be given in coronal plane on a tilted head (perpendicular to the line of 3rd ventricle and brain stem). Check the positioning block in the other two planes. Slices must be sufficient to cover the whole brain from the vertex up to the line of the foramen magnum. Plan the axial slices on the sagittal plane angle the position block parallel to the anterior and posterior margin of the corpus callosum. Suggested protocols, parameters and planningĪ three plane localiser must be taken in the beginning to localise and plan the sequences. Give cushions under the legs for extra comfortĬentre the laser beam localizer over the glabella Position the head in the head coil and immobilise with cushions Offer earplugs or headphones, possibly with music for extra comfort Gadolinium should only be given to the patient if GFR is > 30 relative or staff )Ĭontrast injection risk and benefits must be explained to the patient before the scan If possible provide a chaperone for claustrophobic patients (e.g. Patient preparatio n i nternal auditory meatus(iams) MRI scanĪ satisfactory written consent form must be taken from the patient before entering the scanner roomĪsk the patient to remove all metal objects including keys, coins, wallet, cards with magnetic strips, jewellery, hearing aid and hairpins Pregnancy (risk vs benefit ratio to be assessed) Intracranial aneurysm clips (unless made of titanium) cardiac pacemaker, insulin pump biostimulator, neurostimulator, cochlear implant, and hearing aids) Contraindications internal auditory meatus(iams) MRI scanĪny electrically, magnetically or mechanically activated implant (e.g.
0 kommentar(er)
