title: Quantitative susceptibility mapping at 3 T: comparison of acquisition methodologies.
abstract: Quantitative susceptibility mapping (QSM) is fast becoming a routine clinical tool in the evaluation and assessment of neurological diseases. Unfortunately, there is currently no established standard scanning protocol, and it is uncertain whether different acquisition strategies alter the derived estimates of magnetic susceptibility. Here, we compare some key deep grey matter susceptibility values in healthy adults acquired from various QSM sequences using either unipolar or bipolar readout gradients, accelerated imaging or not, and gradient-warp correction or not. Four healthy adult volunteers were scanned three times each within 4 days at 3 T. The eight different QSM combinations were acquired in different randomised order for each session, and then co-registered to an anatomical atlas. The average and standard deviations of magnetic susceptibilities in the caudate, putamen, red nucleus, internal and external globus pallidus were used in a linear mixed effects model to determine the influence of the various acquisition parameters. Gradient-warp correction was the only statistically significant fixed effect (p < 0.01), but its impact was small (~5% change) compared with the overall fixed effects. The random effects coefficients (i.e. the various tissues) were statistically significant. Based on our limited multiple observations in healthy adult volunteers, the susceptibilities in deep grey matter are statistically equivalent when QSM source data are acquired with or without accelerated imaging using either unipolar or bipolar readout gradients. There is, however, a statistically meaningful, but small, difference if gradient-warp correction is used or not. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Departments of Radiology & Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.|Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services, Calgary, AB, Canada.
authors.forename: M Louis
authors.initials: ML
authors.lastname: Lauzon
authors.affiliation: Departments of Radiology & Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.|Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services, Calgary, AB, Canada.
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: McCreary
authors.affiliation: Departments of Radiology & Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.|Calgary Image Processing and Analysis Centre, Calgary, AB, Canada.
authors.forename: D Adam
authors.initials: DA
authors.lastname: McLean
authors.affiliation: Departments of Radiology & Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.|Calgary Image Processing and Analysis Centre, Calgary, AB, Canada.
authors.forename: Marina
authors.initials: M
authors.lastname: Salluzzi
authors.affiliation: Departments of Radiology & Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.|Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services, Calgary, AB, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Frayne
mesh_terms: D000368:Aged; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D001923:Brain Chemistry; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: QSM; gradient-warp correction; methodology; parallel imaging; readout gradient polarity; susceptibility