Assessing effects of scanner upgrades for clinical studies

<jats:sec><jats:title>Background</jats:title><jats:p>Scanner upgrades due to software and hardware changes are an inevitable part of MR research and, without quality assurance protocols, can jeopardize studies.</jats:p></jats:sec><jats:sec><jats:title>Purpose</jats:title><jats:p>To evaluate changes in T<jats:sub>1</jats:sub> relaxation time by inversion recovery (IR) and variable flip angle (VFA) measurements on a 3T system that underwent an "everything but the magnet" upgrade.</jats:p></jats:sec><jats:sec><jats:title>Study Type</jats:title><jats:p>Longitudinal.</jats:p></jats:sec><jats:sec><jats:title>Phantom</jats:title><jats:p>An International Society of Magnetic Resonance in Medicine / National Institute of Standards and Technology (ISMRM/NIST) system phantom with repeated measurements across multiple (<jats:italic>n</jats:italic> = 3) days.</jats:p></jats:sec><jats:sec><jats:title>Field Strength/Sequence</jats:title><jats:p>T<jats:sub>1</jats:sub> IR, VFA at 3T.</jats:p></jats:sec><jats:sec><jats:title>Assessment</jats:title><jats:p>The T<jats:sub>1</jats:sub> measurements by IR and VFA were compared with the nuclear magnetic resonance (NMR) measurements, which constitute the known values for the ISMRM/NIST system phantom, to determine the measurement error.</jats:p></jats:sec><jats:sec><jats:title>Statistical Tests</jats:title><jats:p>Descriptive.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The T<jats:sub>1</jats:sub> VFA measurement errors were distributed around zero (–15% to +10%) on the original system and then the errors were distributed entirely above zero post‐upgrade (+5% to 30%). The T<jats:sub>1</jats:sub> IR results had a dramatic increase in error distribution (±5% original, ±20% post‐upgrade) prior to the identification of signal saturation as an issue. Once the signal saturation was accounted for, the T<jats:sub>1</jats:sub> IR errors decreased to ±10% post‐upgrade.</jats:p></jats:sec><jats:sec><jats:title>Data Conclusion</jats:title><jats:p>The T<jats:sub>1</jats:sub> VFA measurement differences between the original and post‐upgrade systems can be entirely attributed to contributions from B<jats:sub>1</jats:sub>. The T<jats:sub>1</jats:sub> IR measurements demonstrate the need for quantitative quality assurance (QA) processes. The site under study passed the QA protocols in place, which did not identify the increased T<jats:sub>1</jats:sub> error, nor the signal saturation issue. To improve on this study, we would make systematic, quantitative measurements at intervals less than a year and following any hardware or software upgrade.</jats:p><jats:p><jats:bold>Level of Evidence:</jats:bold> 1</jats:p><jats:p><jats:bold>Technical Efficacy:</jats:bold> Stage 2</jats:p><jats:p>J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2019;50:1948–1954.</jats:p></jats:sec>