Thomas Leonard Chenevert PhD, Presenter: Consultant, Koninklijke Philips Electronics NV

Dariya Malyarenko, Abstract Co-Author: Nothing to Disclose

Craig J. Galban PhD, Abstract Co-Author: Inventor, ImBio, LLC

Charles R. Meyer PhD, Abstract Co-Author: Nothing to Disclose

Timothy D. Johnson PhD, Abstract Co-Author: Nothing to Disclose

Alnawaz Rehemtulla PhD, Abstract Co-Author: Stockholder, ImBio, LLC

Brian Dale Ross PhD, Abstract Co-Author: Co-founder, ImBio, LLC Shareholder, ImBio, LLC Advisor, ImBio, LLC

This study was undertaken to determine the extent of quantitative agreement for ADC values of a known, temperature-controlled fluid measured on multiple platforms, sites, and field-strength MR systems using a common acquisition protocol. Development of quantitative quality control procedures were developed to ascertain the technical variability in multi-center measurements of the diffusion coefficient of water as a prerequisite to use the apparent diffusion coefficient (ADC) as a biomarker in multi-center clinical trials.

A standardized data acquisition protocol was developed which was used at 18 participating test sites to acquire measurements from a temperature-controlled diffusion phantom which was provided to each site. Usable diffusion weighted imaging data of ice water at 5 b-values were collected from a total of 35 clinical MRI systems from 3 different vendors at 2 field strengths (1.5 and 3T) which were analyzed at a centralized processing site.

The standard deviation of bore-center ADC values was determined to be <2% measured across all 35 scanners (error range of -2% to +5%). Daily repeatability (2xstd/mean) of the measurement was determined to be within 4.5% while intra-exam repeatability at the phantom center was within 1%. Excluding one outlier, inter-site reproducibility of ADC at magnet isocenter was within 3%, though variability was found to increase for off-isocenter measurements. Significant (>10%) system-specific and vendor-specific spatial non-uniformity ADC bias was also found for the off-center measurement consistent with non-linear gradient performance.

Through standardization of DWI protocols, reproducibility of ADC measurements improved and revealed spatial ADC non-uniformity as a source of error in multi-site clinical studies. These non-uniformities are correctable using a priori knowledge of gradient coil characteristics.

Detection of clinically-significant changes in ADC require the sources of technical variability to be well characterized. For this a phantom capable of absolute diffusion measurement is required.

Chenevert, T, Malyarenko, D, Galban, C, Meyer, C, Johnson, T, Rehemtulla, A, Ross, B, Evaluation of an Ice Water Phantom for Assessment of Apparent Diffusion Coefficient Repeatability and Reproducibility Across Multiple Systems.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12034685.html