Magnetic resonance imaging (MRI) is a test that uses a magnetic field and radio waves to produce detailed images of the structures. The MRI machine is a large, cylindrical (tube-shaped) machine that creates a strong magnetic field around the patient. The magnetic field, along with radio waves, alters the hydrogen atoms' natural alignment in the body. Pulses of radio waves sent from a scanner knock the nuclei in your atoms out of their normal position. As the nuclei realign back into proper position, the nuclei send out radio signals. These signals are received by a computer that analyzes and converts them into a two-dimensional (2D) image of the body structure or organ being examined.
MRI brain imaging acquired a firm position in clinical practice and medical research as a powerful means of detecting both anatomic and functional information about the brain.
Headaches are described as primary (where no contributing cause is found) or secondary (where a discrete lesion or other condition has triggered the event).
The decision to use MRI is a common dilemma facing clinicians, particularly as primary headache phenotypes can be triggered by secondary causes. Studies demonstrate that there is no appreciable difference in the frequency of pathological and incidental findings in common headache populations compared with the general community. Imaging is therefore not routinely required where a primary headache diagnosis can be made.
Approximately 0.1% of headaches are sinister (i.e., secondary headaches, which include neoplasm, aneurysm rupture, venous sinus thrombosis, meningitis, etc.). Among patients with migraine and a normal neurological examination, the prevalence of significant intracranial abnormalities on neuroimaging ranges from 0 to 3.1% and combining this data in a meta-analysis resulted in a prevalence of 0.18%. Specifically, the prevalence of arteriovenous malformations is 0.8% and saccular aneurysms is 2.4% on autopsy.
Micieli, A., & Kingston, W. (2019). An Approach to Identifying Headache Patients That Require Neuroimaging. Frontiers in public health, 7, 52. https://doi.org/10.3389/fpubh.2019.00052
Serag, D., Ragab, E. Prevalence of incidentally discovered findings on brain MRI in adult Egyptian population. Egypt J Radiol Nucl Med 51, 65 (2020). https://doi.org/10.1186/s43055-020-00187-1
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Neurological-Diagnostic-Tests-and-Procedures-Fact
https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/magnetic-resonance-imaging-mri-of-the-spine-and-brain
https://www.nejm.org/doi/full/10.1056/nejmoa070972