A multimodal analysis of Magnetic Resonance Imaging for the study of brain abnormalities in migraine: gray matter morphometry, white matter integrity and structural connectivity

Abstract

Migraine is one of the most common causes of disability, especially among young women. Despite the high migraine prevalence and its consequences, currently there are no migraine biomarkers and the diagnosis is exclusively based on the description of the symptoms by the patient. Furthermore, the migraine pathophysiology is not completely understood yet. In order to find a migraine biomarker and better understand the migraine pathophysiology, Magnetic Resonance Imaging (MRI) has been employed thanks to its excellent tissue contrast and spatial resolution using non-ionizing radiation. Multiple studies that have assessed gray matter and white matter structure in patients with migraine have shown conflicting results, although some patterns such as loss of gray matter volume have been widely described. From the clinical point of view, other important assessments like the comparison between the two current main migraine types, Chronic Migraine (CM) and Episodic Migraine (EM), have been barely carried out. Considering the technical perspective, specific evaluations of the structural connections between gray matter regions and the relationships between the MRI findings from different modalities have not been performed. In the present doctoral thesis, the main objective was the characterization of gray matter and white matter structural properties of patients with CM and EM. With regard to both migraine groups, the comparison between the two migraine types through the employment of diverse MRI processing techniques is also included in the main objective. The use of advanced and novel diffusion measures not employed previously in the migraine literature was also considered to provide an additional strategy for the assessment of white matter. An evaluation of the diffusion MRI (dMRI) acquisition parameters in association with the sample size was carried out to identify possible sources of the variability. Moreover, the structural connections between gray matter regions through the white matter tracts were assessed, bearing in mind their possible relationship with gray matter morphometry.