When to Order MRI Head With Versus Without Contrast
MRI head without contrast is the preferred initial imaging choice for most neurological conditions, while MRI with and without contrast should be reserved for specific clinical scenarios where enhancement patterns are diagnostically important, such as suspected tumors, infections, or inflammatory conditions.
General Principles for MRI Head Ordering
MRI Without Contrast (Non-Contrast) is Appropriate For:
- Acute stroke evaluation - Non-contrast MRI is usually appropriate for initial imaging of acute stroke in both adults and children 1
- Altered mental status without focal neurological deficits 1
- Suspected vascular abnormalities - Initial evaluation of arteriopathies, moyamoya, or vascular malformations 1
- Trauma evaluation
- Headache without concerning features
- Seizure disorders
- Neurodegenerative disorders
MRI With and Without Contrast is Appropriate For:
- Suspected intracranial mass/tumor - Enhancement patterns help characterize lesions 1
- Suspected infection (meningitis, encephalitis, abscess) 1
- Inflammatory conditions - Multiple sclerosis, vasculitis, autoimmune encephalitis 1
- Suspected central nervous system vasculitis 1
- Evaluation of nontraumatic intraparenchymal hemorrhage of unknown etiology 1
- Persistent or worsening altered mental status despite clinical management of suspected underlying cause 1
Clinical Decision Algorithm
Start with non-contrast MRI when:
- Evaluating acute stroke
- Initial screening for most neurological conditions
- Patient has contraindication to contrast (severe renal impairment, previous allergic reaction)
- Evaluating for structural abnormalities
Order MRI with and without contrast when:
- Enhancement patterns would provide critical diagnostic information
- Evaluating for blood-brain barrier disruption
- Characterizing known lesions
- Suspected infection or inflammation
- Evaluating for leptomeningeal disease
Important Considerations
Contrast administration risks: Gadolinium-based contrast agents carry risks including nephrogenic systemic fibrosis in patients with renal impairment and potential gadolinium deposition in brain tissue with repeated exposures.
Timing considerations: In acute stroke, non-contrast MRI with diffusion-weighted imaging (DWI) can detect ischemic changes within minutes of onset, while contrast-enhanced studies may not add significant diagnostic value in the hyperacute setting 2, 3.
Potential pitfalls: Recent administration of iodinated contrast (from CT or angiography) can affect MRI interpretation for up to 48 hours, potentially leading to false positive hemorrhage interpretations 4.
Detection of hemorrhage: Non-contrast MRI sequences, particularly gradient-recalled echo (GRE) or susceptibility-weighted imaging (SWI), are highly sensitive for detecting both acute and chronic hemorrhage, potentially more sensitive than CT 5, 3.
Advanced non-contrast techniques: Techniques like arterial spin labeling (ASL) and time-of-flight MRA can provide perfusion and vascular information without contrast, which is particularly valuable in patients with contraindications to contrast administration 3.
By following these guidelines, clinicians can optimize the diagnostic yield of MRI while minimizing unnecessary contrast administration and its associated risks.