High-field diffusion MR histology: image-based correction of eddy-current ghosts in diffusion-weighted rapid acquisition with relaxation enhancement (DW-RARE).
High-resolution, diffusion-weighted (DW) MR microscopy is gaining increasing acceptance as a nondestructive histological tool for the study of fixed tissue samples. Spin-echo sequences are popular for high-field diffusion imaging due to their high tolerance to B(0) field inhomogeneities. Volumetric DW rapid acquisition with relaxation enhancement (DW-RARE) currently offers the best tradeoff between imaging efficiency and image quality, but is relatively sensitive to residual eddy-current effects on the echo train phase, resulting in encoding direction-dependent ghosting in the DW images. We introduce two efficient, image-based phase corrections for ghost artifact reduction in DW-RARE of fixed tissue samples, neither of which require navigator echo acquisition. Both methods rely on the phase difference in k-space between the unweighted reference image and a given DW image and assume a constant, per-echo phase error arising from residual eddy-current effects in the absence of sample motion. Significant qualitative and quantitative ghost artifact reductions are demonstrated for individual DW and calculated diffusion tensor images.
Tyszka
J Michael
JM
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
Frank
Lawrence R
LR
D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D066298:In Vitro Techniques; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity