From a historical perspective, the main clinical utility of MRI has been its strength in superior resolution of neurological soft tissues, far more than that is able to be seen with Computed Tomography (CT). MRI easily distinguishes grey from white matter, excludes focal intracerebral (or intra-axial) lesions from extra-axial lesions and can perform angiography of the circle of Willis without the need for contrast.
Common conditions requiring MRI evaluation include demyelination disorders such as multiple sclerosis (MS), primary and secondary tumours, strokes, aneurysms and infections. All these may result in a positive clinical history of headaches and/or seizures, making MRI the imaging modality of choice.
CT is the main imaging modality used in the context of trauma as it is widely available and reliably demonstrates haemorrhage from normal cerebral tissue. The main disadvantage of CT is the use of ionising radiation.
Figure 1. Coronal post contrast MRI of the brain in a patient presenting with a headache demonstrates an enhancing mass of the right lateral ventricle (arrow) that was pathologically confirmed to be a primary brain tumour, in this instance a central neurocytoma.
Figure 2. Sagittal post contrast MRI of the brain in a patient with a history of melanoma and new onset of seizures demonstrates an enhancing lesion (arrow) in keeping with a solitary metastasis.
MBS item description
Referral by a medical practitioner (excluding a specialist or consultant physician) for a MRI scan of head for a patient 16 years or older for:
- unexplained seizure(s)
- unexplained chronic headache with suspected intracranial pathology
MRI scans that are eligible for the Medicare rebate referred by GPs are bulk billed at Melbourne Radiology Clinic.
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