Relaxation measurements of an MRI system phantom at low magnetic field strengths

OBJECTIVE: Temperature controlled T(1) and T(2) relaxation times are measured on NiCl(2) and MnCl(2) solutions from the ISMRM/NIST system phantom at low magnetic field strengths of 6.5 mT, 64 mT and 550 mT. MATERIALS AND METHODS: The T(1) and T(2) were measured of five samples with increasing concentrations of NiCl(2) and five samples with increasing concentrations of MnCl(2). All samples were scanned at 6.5 mT, 64 mT and 550 mT, at sample temperatures ranging from 10 °C to 37 °C. RESULTS: The NiCl(2) solutions showed little change in T(1) and T(2) with magnetic field strength, and both relaxation times decreased with increasing temperature. The MnCl(2) solutions showed an increase in T(1) and a decrease in T(2) with increasing magnetic field strength, and both T(1) and T(2) increased with increasing temperature. DISCUSSION: The low field relaxation rates of the NiCl(2) and MnCl(2) arrays in the ISMRM/NIST system phantom are investigated and compared to results from clinical field strengths of 1.5 T and 3.0 T. The measurements can be used as a benchmark for MRI system functionality and stability, especially when MRI systems are taken out of the radiology suite or laboratory and into less traditional environments. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10334-023-01086-y.