Demonstration of nonlinearity bias in the measurement of the apparent diffusion coefficient in multicenter trials.
OBJECTIVE
Characterize system-specific bias across common magnetic resonance imaging (MRI) platforms for quantitative diffusion measurements in multicenter trials.


METHODS
Diffusion weighted imaging (DWI) was performed on an ice-water phantom along the superior-inferior (SI) and right-left (RL) orientations spanning ± 150 mm. The same scanning protocol was implemented on 14 MRI systems at seven imaging centers. The bias was estimated as a deviation of measured from known apparent diffusion coefficient (ADC) along individual DWI directions. The relative contributions of gradient nonlinearity, shim errors, imaging gradients, and eddy currents were assessed independently. The observed bias errors were compared with numerical models.


RESULTS
The measured systematic ADC errors scaled quadratically with offset from isocenter, and ranged between -55% (SI) and 25% (RL). Nonlinearity bias was dependent on system design and diffusion gradient direction. Consistent with numerical models, minor ADC errors (± 5%) due to shim, imaging and eddy currents were mitigated by double echo DWI and image coregistration of individual gradient directions.


CONCLUSIONS
The analysis confirms gradient nonlinearity as a major source of spatial DW bias and variability in off-center ADC measurements across MRI platforms, with minor contributions from shim, imaging gradients and eddy currents. The developed protocol enables empiric description of systematic bias in multicenter quantitative DWI studies.
Radiology, University of Michigan, Ann Arbor, Michigan, USA.
Dariya I
DI
Malyarenko
Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
David
D
Newitt
Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
Lisa
L
J Wilmes
Diagnostic Radiology, Oregon Health and Science University, Portland, Oregon, USA.
Alina
A
Tudorica
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.
Karl G
KG
Helmer
Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
Lori R
LR
Arlinghaus
John Hopkins University School of Medicine, Baltimore, Maryland, USA.
Michael A
MA
Jacobs
Translational and Molecular Imaging Institute Icahn School of Medicine at Mount Sinai, New York, USA.
Guido
G
Jajamovich
Translational and Molecular Imaging Institute Icahn School of Medicine at Mount Sinai, New York, USA.
Bachir
B
Taouli
Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Departments of Radiology, Physics and Cancer Biology, Vanderbilt University, Nashville, Tennessee, USA.
Thomas E
TE
Yankeelov
Advanced Imaging Research Center, Oregon Health and Science University, Portland, Oregon, USA.
Wei
W
Huang
Radiology, University of Michigan, Ann Arbor, Michigan, USA.
Thomas L
TL
Chenevert
D015982:Bias; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D015337:Multicenter Studies as Topic / Q000592:standards*; D017711:Nonlinear Dynamics; D019047:Phantoms, Imaging
ADC mapping; gradient nonlinearity; multicenter trials; quantitative diffusion MRI