Image registration and subtraction to detect active T(2) lesions in MS: an interobserver study

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Serial MRI scans are crucial for evaluating multiple sclerosis (MS) lesion volume changes in clinical trials.
• Traditional volume analysis is time-consuming and prone to quantification errors.
• Assessing lesion number or size changes using subtracted images offers a more precise evaluation of MS disease activity.

Purpose of the Study:

• To evaluate the interobserver agreement in detecting active MS lesions using subtracted MRI images.
• To determine the reliability of subtracted images for assessing MS disease progression in clinical trials.

Main Methods:

• Paired dual-echo T2-weighted spin-echo MRI studies from 30 MS patients were analyzed.
• An automatic matching algorithm registered follow-up scans to baseline scans.
• Six observers identified new, enlarging, resolving, and shrinking lesions on subtracted images after guideline training.

Main Results:

• Good interobserver agreement was found for detecting new MS lesions (kappa 0.69).
• Combining new and enlarging lesions showed good agreement for "positive" disease activity (kappa 0.71).
• Moderate agreement was observed for enlarging (kappa 0.52) and shrinking lesions (kappa 0.53), while agreement for resolving lesions was poor (kappa 0.31).

Conclusions:

• Subtracted MRI images provide a reliable and time-efficient method for assessing "positive" MS disease activity.
• This technique enhances the visual detection of new T2 lesions, improving interobserver agreement in clinical trials.
• Subtracted images offer a valuable tool for monitoring MS progression.