Imaging chronic active lesions in multiple sclerosis: a consensus statement.

Area of Science:

• Neuroimaging
• Neurology
• Inflammation research

Background:

• Chronic active lesions (CAL) are key indicators of chronic inflammation in multiple sclerosis (MS), impacting disease progression.
• Recent advancements in MRI and PET imaging allow for in vivo detection and quantification of CAL in MS patients.

Purpose of the Study:

• To present a consensus statement from the North American Imaging in Multiple Sclerosis Cooperative on the radiological definition and measurement of CAL.
• To summarize the development process of this consensus statement and highlight existing knowledge gaps.

Main Methods:

• Review of innovative MRI and PET-derived biomarkers for CAL detection, including paramagnetic rim lesions and 18-kDa translocator protein-positive lesions.
• Development of a consensus statement providing radiological guidance for CAL identification, quantification, and monitoring.

Main Results:

• Identification of promising candidate biomarkers for CAL, such as paramagnetic rim lesions and slowly expanding lesions on MRI, and 18-kDa translocator protein-positive lesions on PET.
• Acknowledgement that current biomarkers have overlapping but not equivalent sensitivity and specificity compared to histopathological CAL.
• Highlighting the lack of standardization in current imaging measures for CAL.

Conclusions:

• The consensus statement offers crucial guidance for standardizing CAL assessment in MS.
• Further research is needed to address remaining knowledge gaps and refine imaging biomarkers for more accurate CAL detection and monitoring.