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

Abstract

The [C]PIB PET tracer, originally developed for amyloid imaging, has been recently repurposed to quantify demyelination and remyelination in multiple sclerosis (MS). Myelin PET imaging, however, is limited by its low resolution that deteriorates the quantification accuracy of white matter (WM) lesions. Here, we introduce a novel partial volume correction (PVC) method called Multiresolution-Multimodal Resolution-Recovery (MM-RR), which uses the wavelet transform and a synergistic statistical model to exploit MRI structural images to improve the resolution of [C]PIB PET myelin imaging. MM-RR performance was tested on a phantom acquisition and in a dataset comprising [C]PIB PET and MR T1- and T2-weighted images of 8 healthy controls and 20 MS patients. For the control group, the MM-RR PET images showed an average increase of 5.7% in WM uptake while the grey-matter (GM) uptake remained constant, resulting in +31% WM/GM contrast. Furthermore, MM-RR PET binding maps correlated significantly with the mRNA expressions of the most represented proteins in the myelin sheath (R= 0.57 ± 0.09). In the patient group, MM-RR PET images showed sharper lesion contours and significant improvement in normal-appearing tissue/WM-lesion contrast compared to standard PET (contrast improvement > +40%). These results were consistent with MM-RR performances in phantom experiments.

Increased Cerebral Blood Flow after single dose of antipsychotics in healthy volunteers depends on dopamine D2 receptor density profiles

“…This is consistent with our hypothesis motivated by the existence of a large variability between mRNA expression and protein synthesis due to post-transcriptional regulation mechanisms (Liu et al, 2016). Our findings are consistent with previous works that have linked the spatial architecture of the brain transcriptome to brain structure (Grecchi et al, 2017;Veronese et al, 2015), function (Hawrylycz et al, 2015;Richiardi et al, 2015) and in vivo measures of brain proteins (Gryglewski et al, 2018;Rizzo et al, 2014;Veronese et al, 2016a). Here we could show that post mortem brain mRNA expression data may potentially be used to map also variations in MRI-based functional response to drug stimulation.…”

Increased cerebral blood flow after single dose of antipsychotics in healthy volunteers depends on dopamine D2 receptor density profiles

“…(Liu et al, 2016). Our findings are consistent with previous works that have linked the spatial architecture of the brain transcriptome to brain structure (Grecchi et al, 2017;Veronese et al, 2015), function (Hawrylycz et al, 2015;Richiardi et al, 2015) and in vivo measures of brain proteins (Gryglewski et al, 2018;Rizzo et al, 2016;Veronese et al, 2016). Here we could show that post mortem brain mRNA expression data may potentially be used to map also variations in MRI functional response to drug stimulation.…”

[18F]Florbetapir PET/MR imaging to assess demyelination in multiple sclerosis

“…Radioligands developed to measure amyloid-β pathology in grey matter for Alzheimer's disease, such as [ 11 [8][9][10] also showed affinity for myelin protein. This is due to the fact that these stilbene and benzothiazole derivatives have a very flat structure, interacting with the secondary structure of myelin basic protein similarly to the way they interact with amyloid [11,12]. In fact, in healthy white matter, myelin basic protein has a particular two-dimensional secondary structure as it acts as a hinge between lipid bilayers.…”