Multicenter Evaluation of Geometric Accuracy of MRI Protocols Used in Experimental Stroke.
It has recently been suggested that multicenter preclinical stroke studies should be carried out to improve translation from bench to bedside, but the accuracy of magnetic resonance imaging (MRI) scanners routinely used in experimental stroke has not yet been evaluated. We aimed to assess and compare geometric accuracy of preclinical scanners and examine the longitudinal stability of one scanner using a simple quality assurance (QA) protocol. Six 7 Tesla animal scanners across six different preclinical imaging centers throughout Europe were used to scan a small structural phantom and estimate linear scaling errors in all orthogonal directions and volumetric errors. Between-scanner imaging consisted of a standard sequence and each center's preferred sequence for the assessment of infarct size in rat models of stroke. The standard sequence was also used to evaluate the drift in accuracy of the worst performing scanner over a period of six months following basic gradient calibration. Scaling and volumetric errors using the standard sequence were less variable than corresponding errors using different stroke sequences. The errors for one scanner, estimated using the standard sequence, were very high (above 4% scaling errors for each orthogonal direction, 18.73% volumetric error). Calibration of the gradient coils in this system reduced scaling errors to within ±1.0%; these remained stable during the subsequent 6-month assessment. In conclusion, despite decades of use in experimental studies, preclinical MRI still suffers from poor and variable geometric accuracy, influenced by the use of miscalibrated systems and various types of sequences for the same purpose. For effective pooling of data in multicenter studies, centers should adopt standardized procedures for system QA and in vivo imaging.
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Xenios
X
Milidonis
University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.|Edinburgh Preclinical Imaging, University of Edinburgh, Edinburgh, United Kingdom.
Ross J
RJ
Lennen
University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.|Edinburgh Preclinical Imaging, University of Edinburgh, Edinburgh, United Kingdom.
Maurits A
MA
Jansen
Department of Experimental Neurology, Center for Stroke Research Berlin, Charité University Medicine Berlin, Berlin, Germany.|Core Facility 7 T Experimental MRIs, Center for Stroke Research Berlin and Cluster of Excellence NeuroCure, Charité University Medicine Berlin, Berlin, Germany.
Susanne
S
Mueller
Department of Experimental Neurology, Center for Stroke Research Berlin, Charité University Medicine Berlin, Berlin, Germany.|Core Facility 7 T Experimental MRIs, Center for Stroke Research Berlin and Cluster of Excellence NeuroCure, Charité University Medicine Berlin, Berlin, Germany.
Philipp
P
Boehm-Sturm
Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.
William M
WM
Holmes
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Emily S
ES
Sena
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Malcolm R
MR
Macleod
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.|Edinburgh Preclinical Imaging, University of Edinburgh, Edinburgh, United Kingdom.
Ian
I
Marshall
D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012015:Reference Standards; D020521:Stroke / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed