DPU - Symposium 2022

Medica l Image Ana lysis & Ar t i f icia l Intel l igence Symposium 2022 Nr. 9: Dipl.-Ing. Philipp Lazen, BSc: B1+ Corrected Metabolite Concentration Estimates from 7 T FID CRT MRSI Curriculum Vitae: Dipl.-Ing. Philipp Lazen, BSc is a PhD student in his second year at the Medical University of Vienna. He works on MR spectroscopic imaging (MRSI). For his master thesis I developed a pulse simulation model which can be used to test different excitation pulses in a numerical phantom. His PhD focuses on various approaches towards improving MRSI, such as the application of higher order shim coils as well as post processing methods like B1 correction. Additionally, he is involved in various clinical studies involving clinical patients and healthy volunteers. As such, his work unites aspects of software development and coding, data science and analysis, and biology and medicine. Abstract: B1 + Corrected Metabolite Concentration Estimates from 7 T FID CRTMRSI Magnetic resonance spectroscopic imaging (MRSI) is an imaging modality similar to MR imaging that can map distributions of metabolites in tissues, such as the brain. Conventionally, MRSI offers only qualitative measurements, but no absolute metabolite concentrations. As a remedy, metabolite ratios are commonly used to provide better comparability between subjects and MR scanners, but a more sophisticated solution is the calculation of metabolite concentration estimates (CE) based on internal water referencing. Additionally, MRSI – like all MR based modalities – can suffer from inhomogeneities of the involved magnetic fields, which reduce the reliability of the acquired results. For example, magnetic excitation pulses are naturally imperfect and result in a spatially inhomogeneous transmit field B1 +, causing the resulting signal strength in a voxel to vary with its location. In this study, we calculated metabolite CEs in a cohort of healthy volunteers and corrected the resulting values for B1 + inhomogeneities.