Do you order MRI with or without contrast to rule out Multiple Sclerosis?

MRI Protocol for Ruling Out Multiple Sclerosis

Order MRI with contrast (gadolinium) for the initial diagnostic workup of multiple sclerosis. 1

Brain MRI Protocol

The standardized diagnostic protocol must include both pre- and post-contrast T1-weighted sequences along with T2-weighted imaging. 1 The MAGNIMS consensus guidelines explicitly state that the standardized protocol for conventional MRI in diagnostic work-up includes axial T1-weighted sequences before and after contrast, axial T2-weighted and proton-density (or T2-FLAIR) sequences, and sagittal 2D or isotropic 3D T2-FLAIR sequences. 1

Why Contrast is Essential

• Gadolinium enhancement detects acute inflammatory activity by identifying blood-brain barrier breakdown, which helps establish dissemination in time even on a single scan. 1
• A single gadolinium-enhanced MRI can potentially provide evidence for both dissemination in space and time simultaneously, which accelerates diagnosis. 2
• Contrast helps differentiate acute from chronic lesions, which T2-weighted sequences alone cannot accomplish. 1, 2
• Contrast enhancement patterns help exclude MS mimics such as tumors, vascular malformations, and leptomeningeal disease—persistent enhancement beyond 3 months or lesions with mass effect suggest alternative diagnoses. 2

Technical Specifications

• Use a minimum field strength of 1.5 T, preferably 3.0 T, with slice thickness of 3 mm for 2D sequences. 1
• Administer a single dose (0.1 mmol/kg body weight) of gadolinium-based contrast medium with a minimum delay of 5 minutes after injection before acquiring post-contrast images. 1
• At 1.5 T, use conventional 2D spin-echo sequences to detect gadolinium-enhancing MS lesions; at 3.0 T, isotropic 3D gradient-echo or fast spin-echo sequences are acceptable alternatives. 1

Spinal Cord MRI Protocol

Always include spinal cord MRI in the initial diagnostic workup, particularly in specific clinical scenarios. 1, 3

Mandatory Indications for Spinal Cord Imaging

• Patients presenting with spinal cord symptoms at disease onset require spinal cord MRI to detect symptomatic lesions and rule out non-demyelinating pathology. 1
• When brain MRI is equivocal or inconclusive (showing only 1-2 lesions that don't fulfill dissemination in space criteria), spinal cord imaging can provide additional lesions to meet diagnostic thresholds. 1
• Patients without spinal symptoms should still be considered for spinal cord MRI, as asymptomatic cord lesions are found in 30-40% of patients with clinically isolated syndrome and predict conversion to clinically definite MS. 1, 3

Spinal Cord Contrast Protocol

The approach to contrast in spinal cord imaging differs from brain imaging. 1 The guidelines recommend a "one-stop shop" strategy where spinal cord MRI is performed directly after contrast-enhanced brain MRI, saving time and avoiding additional contrast administration. 1

• Contrast-enhanced T1-weighted spin-echo sequences are mandatory only if T2 lesions are present on the initial sagittal sequences. 1
• Only a small percentage of spinal cord lesions show contrast enhancement, and those that do are commonly associated with new clinical symptoms. 1

Spinal Cord Technical Requirements

• Minimum field strength of 1.5 T (unlike brain imaging, 3.0 T confers no additional diagnostic value for spinal cord). 1
• Mandatory sagittal sequences include: dual-echo (proton-density and T2-weighted) conventional and/or fast spin-echo, plus STIR as an alternative to proton-density-weighted. 1
• Slice thickness of 3 mm with at least two sets of sagittal images with different contrasts to increase confidence in lesion detection. 1

Critical Diagnostic Considerations

When Contrast Provides Maximum Value

• In patients with a single clinical attack, gadolinium-enhancing lesions can demonstrate dissemination in time if both enhancing and non-enhancing lesions are present simultaneously. 1, 2
• For differential diagnosis, contrast patterns help distinguish MS from neuromyelitis optica spectrum disorders (which show longitudinally extensive enhancement) and tumors (which show persistent enhancement beyond 3 months). 4, 2
• In monitoring disease activity, contrast-enhanced lesions correlate with pathological inflammatory activity and predict concomitant relapses. 5

Common Pitfalls to Avoid

• Never rely solely on T2-weighted sequences for initial diagnostic workup, as they cannot distinguish acute from chronic lesions or provide evidence of dissemination in time on a single scan. 1, 2
• Do not skip spinal cord imaging in patients over 50 or with vascular risk factors, as brain white matter lesions may be nonspecific; spinal cord lesions increase diagnostic specificity. 1
• Avoid diagnosing MS based on MRI alone without appropriate clinical correlation—the lesions detected with MRI are pathologically nonspecific and must be interpreted in the appropriate clinical context. 2
• Ensure standardized protocols are used to allow proper comparative analysis if follow-up scans are needed at different time points or imaging centers. 1

Red Flags Requiring Contrast

• Persistent gadolinium enhancement greater than 3 months suggests alternative diagnoses such as neoplasm rather than MS. 2
• Lesions with mass effect or meningeal enhancement are atypical for MS and require contrast to identify. 2
• Unusual enhancement patterns help identify MS mimics including neuromyelitis optica spectrum disorders and MOG-antibody disease, which require different treatment approaches. 4