Hiroshi Matsuda MD,PhD, Presenter: Nothing to Disclose

Fumio Yamashita PhD, Abstract Co-Author: Nothing to Disclose

Norihide Maikusa PhD, Abstract Co-Author: Nothing to Disclose

Tetsuya Yuasa PhD, Abstract Co-Author: Nothing to Disclose

Kenichiro Tanaka PhD, Abstract Co-Author: Nothing to Disclose

Takeshi Iwatsubo MD, PhD, Abstract Co-Author: Nothing to Disclose

Field intensity inhomogeneity and geometric distortion would hamper reproducibility in brain volumetry using MRI. To overcome these problems, a new automatic correction method was developed and validated in repetitive human brain studies.

The whole brain images using Magnetization Prepared Rapid Acquisition Gradient Echo (MPRAGE) sequences were acquired in 40 healthy adult volunteers of 37 institutes at baseline and one-week later as a preparation study of Japanese Alzheimer’s Disease Neuroimaging Initiative (J-ADNI). A MPRAGE image of a spherical ADNI-phantom containing 165 polycarbonate spheres filled with copper sulfate was obtained at every human study. First human brain images were corrected for field inhomogeneity using B1 calibration data from head and body coils. Then geometric distortion was corrected using a three-dimensional polynomial approximation equation that deforms a distorted phantom image to an originally designed undistorted phantom image. Finally the nonparametric nonuniformity normalization algorithm intensively corrected inhomogeneity. Reproducibility in brain volumetry between baseline and one-week later was assessed in each volunteer using segmented gray matter images. Voxel-based morphometry (VBM), tensor-based morphometry (TBM), and measures of absolute whole gray matter volume were used for these assessments. Moreover FreeSurfer assessed reproducibility of absolute volume measures of hippocampus and entorhinal cortex.

The present correction significantly reduced coefficient of variations (CV) from 8.4 + 10.7 (mean + s.d.) to 5.8 + 7.3 for VBM in medial temporal areas (p<0.05), from 5.9 + 1.1 to 5.4 + 0.7 for TBM in the whole brain (p<0.005), and from 1.0 + 1.3 to 0.4 + 0.4 for absolute whole gray matter volume (p<0.002). FreeSurfer showed a tendency of CV reduction after correction in hippocampus from 1.1 + 1.1 to 1.0 + 1.8 and in entorhinal cortex from 6.1 + 4.9 to 5.2 + 4.5.

The present newly developed correction method for filed intensity inhomogeneity and geometric distortion can provide better reproducibility in longitudinal measures of brain structures using MRI.

High reproducibility in brain volumetry is required for MRI to serve as a biomarker to determine treatments effects in clinical trials involving Alzheimer’s disease and mild cognitive impairment.

Matsuda, H, Yamashita, F, Maikusa, N, Yuasa, T, Tanaka, K, Iwatsubo, T, A New Simultaneous Geometric and Intensity Correction Method for MRI Improves Reproducibility in Volumetry of Brain Structures: Japanese Alzheimers Disease Neuroimaging Initiative.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034286.html