Motion artifacts in standard clinical setting obscure disease-specific differences in quantitative susceptibility...

Area of Science:

• Neuroimaging
• Medical Physics

Background:

• Quantitative susceptibility mapping (QSM) is an emerging MRI technique for visualizing iron and other paramagnetic substances.
• Clinical translation of QSM requires assessing its robustness against patient motion, a common issue in clinical populations like Alzheimer's disease patients.

Purpose of the Study:

• To evaluate the impact of head motion artifacts on the reliability and diagnostic utility of QSM in patients with Alzheimer's disease, mild cognitive impairment, and healthy controls.
• To determine if QSM can detect significant differences in subcortical gray matter susceptibility between these groups under realistic clinical scanning conditions.

Main Methods:

• 3 Tesla MRI scans were acquired from 29 Alzheimer's disease patients, 31 mild cognitive impairment patients, and 41 healthy controls using multi-echo gradient-echo sequences for QSM.
• Motion artifacts were visually assessed by two raters, and QSM was reconstructed using two different algorithms: joint background-field removal and segmentation-enhanced dipole inversion (JANS) and morphology enabled dipole inversion (MEDI).
• Statistical analyses compared quantitative susceptibility values in segmented subcortical gray matter regions between groups, both with and without consideration of motion artifacts.

Main Results:

• A significant proportion of acquired data exhibited visible motion artifacts in both magnitude images and reconstructed QSM.
• No statistically significant differences in QSM were found between the patient and control groups when motion-affected data were included in the analysis.
• When analyzing only subjects without visible motion artifacts, significant QSM differences were detected in the caudate nucleus and putamen between groups.

Conclusions:

• Head motion significantly impacts the reliability of QSM, potentially masking true biological differences between neurological patient groups and healthy controls.
• Current QSM methods may not be sufficiently robust for direct clinical application without implementing additional strategies to restrict or compensate for patient motion.
• Further development of motion-robust QSM techniques is crucial for its successful integration into standard clinical neuroimaging protocols to avoid erroneous diagnostic conclusions.