Abstract #4223

Multisite Investigation of the Effect of Site & Protocol Variation on Fractional Anisotropy

Karl Gerard Helmer¹, Ming-Chung Chou², Allen Song³, Jessica Turner⁴, Barjor Gimi⁵, Susumu Mori⁶

¹Radiology, Massachusetts General Hospital, Charlestown , MA, United States; ²Computer Science & Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan; ³Duke University, Durham, NC, United States; ⁴The Mind Research Network, Albuquerque, NM, United States; ⁵Radiology, Dartmouth Medical School, Hanover, NH, United States; ⁶Radiology, School of Medicine, Johns Hopkins Univerity, Baltimore, MD, United States

Multi-site studies have become ubiquitous when large numbers of subjects are needed. Therefore, the characterization of site and protocol variation effects has become increasingly important. We present data from Siemens, Philips, and GE MR scanners and characterize the behavior of the fractional anisotropy as decreasing amounts of data and/or diffusion-weighted directions are used in the tensor calculation. In addition, the effect of a common protocol variation (TE) is investigated. The methods used in this study are also suitable for the site-reliability characterization before a multi-site study is begun or after upgrades during the study.