Multimodal partial volume correction: Application to [¹¹C]PIB PET/MRI myelin imaging in multiple sclerosis

Area of Science:

• Neuroimaging
• Radiochemistry
• Neurology

Background:

• The [11C]PIB PET tracer is used for amyloid imaging but is now repurposed for multiple sclerosis (MS) demyelination and remyelination quantification.
• Current myelin PET imaging suffers from low resolution, impacting the accuracy of white matter (WM) lesion quantification.

Purpose of the Study:

• To introduce a novel partial volume correction (PVC) method, Multiresolution-Multimodal Resolution-Recovery (MM-RR), to enhance [11C]PIB PET myelin imaging resolution.
• To improve the quantification accuracy of WM lesions in MS using MRI structural images.

Main Methods:

• Developed and applied the MM-RR method, utilizing wavelet transform and a synergistic statistical model.
• Tested MM-RR on phantom data and a dataset of 8 healthy controls and 20 MS patients with [11C]PIB PET and MR T1/T2-weighted images.

Main Results:

• In healthy controls, MM-RR increased WM uptake by 5.7% and WM/GM contrast by 31% without altering GM uptake.
• MM-RR PET binding maps showed significant correlation with myelin sheath protein mRNA expression (R² = 0.57 ± 0.09).
• In MS patients, MM-RR improved lesion contour sharpness and normal-appearing tissue/WM-lesion contrast by over 40% compared to standard PET.

Conclusions:

• The MM-RR method effectively improves the resolution and quantification accuracy of [11C]PIB PET myelin imaging in MS.
• MM-RR enhances WM/GM contrast and lesion visualization, offering a valuable tool for studying demyelination and remyelination in MS.