Does an MRI protocol for Multiple Sclerosis (MS) include contrast, specifically gadolinium-based contrast agents?

MRI Protocol for Multiple Sclerosis Includes Gadolinium Contrast

Yes, MRI protocols for Multiple Sclerosis (MS) include gadolinium-based contrast agents as they are mandatory in the initial diagnostic study when lesions are seen on T2-weighted sequences. 1

Standard MRI Protocol Components for MS

Non-contrast Sequences

• T2-weighted sequences should be acquired in at least two planes, with axial T2 and proton-density (and/or T2-FLAIR) scans combined with sagittal T2-FLAIR being the optimal strategy 1
• Single-slab isotropic 3D T2-FLAIR (voxel size = 1 mm³) could replace 2D T2-FLAIR sequences for better spatial resolution 1
• T2-weighted sequences are more sensitive than T1-weighted ones for demonstrating MS lesions 1

Contrast Enhancement Protocol

• Gadolinium-enhanced (single dose, 0.1 mmol/kg body weight) T1-weighted spin-echo sequences are mandatory in the initial study when lesions are seen on T2-weighted sequences 1
• A minimum delay time of 5 minutes is recommended between gadolinium injection and T1-weighted sequence acquisition 1
• The "dead" time after contrast injection can be used to perform T2-FLAIR sequences to optimize total acquisition time 1

Clinical Value of Contrast in MS Imaging

Initial Diagnostic Study

• Contrast enhancement allows acute lesions to be distinguished from chronic ones, demonstrating dissemination in time (DIT) 1
• The pattern of enhancement helps in differential diagnosis from other conditions that can mimic MS 1
• Enhancement occurs in almost all new lesions which appear during serial monthly scans of patients with relapsing-remitting or secondary progressive MS 1

Follow-up Studies

• In follow-up studies, a postcontrast T1-weighted sequence, though not strictly mandatory, is highly recommended as it facilitates visual detection of new active lesions 1
• This approach is particularly valuable in patients with small lesions or a high lesion load, where lesion detection based only on T2-weighted scans might be difficult 1
• Contrast enhancement is a short-lived feature (typically 2-8 weeks) in most MS lesions, thus helping differentiate recent from older lesions 1

Characteristics of Enhancing MS Lesions

• An enhancing MS lesion is defined as an area of at least 3 mm with clear hyperintensity on T1-weighted images obtained at least 5 minutes after contrast agent administration 1
• Enhancing MS lesions are often nodular, though larger ones can evolve into ring-enhancing lesions 1
• Larger lesions may show "open-ring" enhancement (open towards ventricles or gray matter), which helps differentiate from neoplastic lesions or abscesses 1

Important Considerations

• Safety concerns regarding gadolinium administration and its tendency to accumulate in the brain can be mitigated by using macrocyclic rather than linear agents 1
• Controlling the frequency of gadolinium administration at follow-up is recommended 1
• Lesions that enhance for longer than 3 months are exceptional and should raise suspicion of alternative pathology 1
• Recent research suggests that routine administration of contrast in follow-up studies may not be necessary for patients showing non-progressive disease on non-contrast MRI 2

Spinal Cord MRI Protocol

• For spinal cord imaging, contrast-enhanced T1-weighted spin-echo is recommended if T2 lesions are present 1
• Mandatory sequences include dual-echo (proton-density and T2-weighted) conventional and/or fast spin-echo, STIR, and contrast-enhanced T1-weighted spin-echo (if T2 lesions present) 1