What type of MRI (Magnetic Resonance Imaging) is most appropriate for diagnosing headaches?

MRI Selection for Headache Diagnosis

MRI without contrast is the most appropriate initial imaging study for diagnosing headaches when imaging is indicated, with contrast added only if abnormalities are found on the initial non-contrast scan. 1, 2

Appropriate MRI Selection Based on Headache Type

Primary Headaches

• For primary headaches (migraine, tension-type):
  • Imaging is usually not appropriate unless red flags are present 1
  • When imaging is needed, MRI without contrast is the preferred modality 2

Secondary Headaches

• For suspected secondary headaches:
  • MRI head without IV contrast is the initial study of choice 1
  • Post-contrast imaging should be added only if abnormalities are detected on the non-contrast study 1

Special Headache Scenarios

• Thunderclap headache: Either non-contrast CT head (faster, more sensitive for acute blood) or MRI brain is appropriate; non-contrast MRA should also be considered 1
• Headache with suspected infection: MRI head with AND without IV contrast is recommended 1
• Post-traumatic headache: MRI head without contrast with susceptibility-weighted imaging (SWI) or gradient-echo (GRE) sequences to detect hemosiderin deposition 1

MRI Protocols and Sequences

Standard Protocol

• T1-weighted images
• T2-weighted images
• FLAIR (Fluid-Attenuated Inversion Recovery)
• DWI (Diffusion-Weighted Imaging)

Special Sequences When Indicated

• SWI or GRE: For detecting hemosiderin from prior hemorrhage or trauma 1
• MR Venography (MRV): For suspected venous outflow stenosis or venous sinus thrombosis 1
• MR Angiography (MRA): When vascular abnormalities like aneurysm, AVM, or dissection are suspected 1

When to Use Contrast

• Gadolinium contrast should be reserved for:
  • Abnormal findings on initial non-contrast MRI 1
  • Suspected intracranial infection 1
  • Suspected metastatic disease 3
  • Suspected venous sinus thrombosis (contrast-enhanced MRV) 1

When to Consider CT Instead of MRI

• Emergency settings when rapid assessment is needed 2
• Suspected acute subarachnoid hemorrhage (CT is more sensitive) 3
• When MRI is contraindicated or unavailable 2
• For patients unable to tolerate MRI (claustrophobia, inability to remain still)

Diagnostic Yield and Pitfalls

• Only about 1% of children with headaches have relevant findings on MRI that explain their headaches 2
• In adults with typical primary headaches meeting diagnostic criteria, the yield of clinically significant findings is similarly low 4, 5
• Be aware that incidental findings are common and may lead to unnecessary anxiety and additional testing 4

Red Flags Warranting Imaging

• Sudden severe headache ("thunderclap")
• New headache after age 50
• Progressive or worsening pattern
• Headache that changes with position
• Neurological deficits or abnormal examination
• Immunocompromised state
• History of cancer
• Pregnancy with atypical headache features
• Headache triggered by exertion, Valsalva maneuver, or sexual activity 6

MRI without contrast remains the cornerstone of headache imaging when indicated, with additional sequences and contrast administration guided by specific clinical scenarios and initial imaging findings.