Experimental assessment of clinical MRI-induced global SAR distributions in head phantoms

Accurate estimation of SAR is critical to safeguarding vulnerable patients who require an MRI procedure. The increased static field strength and RF duty cycle capabilities in modern MRI scanners mean that systems can easily exceed safe SAR levels for patients. Advisory protocols routinely used to establish quality assurance protocols are not required to advise on the testing of MRI SAR levels and is not routinely measured in annual medical physics quality assurance checks. This study aims to develop a head phantom and protocol that can independently verify global SAR for MRI clinical scanners. A four-channel birdcage head coil was used for RF transmission and signal reception. Proton resonance shift thermometry was used to estimate SAR. The SAR estimates were verified by comparing results against two other independent measures, then applied to a further four scanners at field strengths of 1.5¿T and 3¿T. Scanner output SAR values ranged from 0.42 to 1.52¿W/kg. Percentage SAR differences between independently estimated values and those calculated by the scanners differed by 0-2.3%. We have developed a quality assurance protocol to independently verify the SAR output of MRI scanners.The project was co-financed by the European Regional Development Fund (ERDF) under Ireland’s European Structural, Investment Funds Programme 2014–2020 and Enterprise Ireland; Grant agreement: CF-2017-0826-P, Irish Research Council postgraduate scholarship GOIPG/2018/82 and the NUI Galway College of Science. Thank you to the NUI Galway Microbiology and physics department for their help creating the phantom. Authors would like to thank Maja Drapiewska and David Connolly from the NUI Galway College of Engineering and Informatics and Eileen Smith from Netzsch for help with DSC measurements.peer-reviewed2020-10-0

Simple Steps to Characterise a Conductivity Measurement Probe for Bio-impedance Applications

Bio-impedance measurements require properly designed and characterised probes. Particular attention must be paid to the excitation signals and temperature compensation to meet the requirements of the linear sample response and the measurement accuracy. Here, we propose a reliable method to characterise probe performance for conductivity measurements of biological samples. This poster was presented at the 23rd International Conference on Biomedical Applications of Electrical Impedance Tomography EIT2023 (12th - 14th June 2023, Aachen, Germany). Conference Proceedings: https://zenodo.org/record/8037618.<br/