Erratum: "The Relationship of Three-Dimensional Human Skull Motion to Brain Tissue Deformation in Magnetic Resonance Elastography Studies" (ASME J. Biomech. Eng., 2017, 139(5), p. 051002; DOI: 10.1115/1.4036146) to Paper Number BIO-16-1363.

Abstract

In this study, displacements of brain tissue in six human subjects and one gelatin "phantom" were measured by MR elastography on two MR scanners. Both were Siemens Trio 3T MRI scanners. One Trio scanner was located at the Beckman Institute at University of Illinois in Urbana-Champaign (UIUC; 4 subjects) and the other Trio scanner was at the Center for Clinical Imaging Research at Washington University in St. Louis (WU; 2 subjects and gel phantom). After publication, we discovered that the default motion-encoding gradient strength was not identical on the two scanners, but was lower on the WU scanner than on the UIUC scanner (20 mT/m vs 26 mT/m on the UIUC scanner). Thus in two subjects and the gel phantom, the estimated displacement amplitudes should be higher by a factor equal to 26/20 (1.3). Correcting this error changes estimates of mean and standard deviation of brain displacement, curl and strain values in the human brain by about 10% (due to 30% error in 2/6 subjects). Corresponding measurements in a gel phantom are also affected; these were included solely for qualitative comparison to the behavior of the brain. No statistical comparisons were affected by these errors. The main conclusions of the study are unchanged.