The role of tissue anisotropy in quantitative brain MRI

In recent years, there have been remarkable advancements in magnetic resonance imaging (MRI), making it possible to obtain high-resolution images of the human body in a clinical setting. This progress has transformed MRI from a tool that primarily produces visual images into one that can provide detailed information about the composition of tissues within the body. However, there is a significant challenge when it comes to accurately mapping the structure of human brain tissue. This challenge arises from the fact that MRI images of the brain are influenced by the orientation of nerve fibers relative to the MRI`s magnetic field. This orientation-dependent effect, called anisotropy, has been found to be as significant as changes related to diseases. Unfortunately, our understanding of how tissue composition and anisotropy affect quantitative MRI (qMRI) is limited, which has become a major obstacle to using qMRI in clinical practice. To address these limitations, a collaborative research project is being conducted at the University of Basel in Switzerland, and the Medical University of Innsbruck in Austria. The project involves diverse investigations of post-mortem brain tissue, healthy volunteers, and patients with specific neurological diseases. The goal is to combine various examinations, such as post-mortem qMRI, in vivo qMRI, along with histological and biochemical analyses, to uncover the origins of anisotropy in qMRI and pave the way towards its clinical application. The researchers aim to investigate how anisotropy can be used as a clinical biomarker in patients with aceruloplasminemia and multiple sclerosis. The expected outcomes of this research are promising. The researchers anticipate observing differences in anisotropy among various qMRI parameters and validating the use of diffusion tensor imaging (DTI) and advanced diffusion modeling. By categorizing qMRI parameters into specific component maps, they expect to identify increased anisotropy related to tissue components, such as lipids and proteins. Importantly, the study aims to identify the underlying tissue components responsible for qMRI anisotropy. This research is of great importance for the field of medicine. It not only sheds light on the origins of anisotropy in qMRI but also offers the potential for precise mapping of tissue composition in patients. By addressing systematic biases in current diagnostic imaging, this research has the potential to enhance the accuracy and effectiveness of clinical practice, ultimately benefiting patients.