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Diffusion imaging with the MP‐rage sequence
Author(s) -
Lee Haakil,
Price Ronald R.
Publication year - 1994
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880040616
Subject(s) - sequence (biology) , diffusion , rage (emotion) , diffusion imaging , diffusion mri , computer science , medicine , computational biology , nuclear magnetic resonance , neuroscience , radiology , magnetic resonance imaging , physics , biology , genetics , thermodynamics
Diffusion‐weighted magnetic resonance (MR) images obtained with conventional spin‐echo techniques are known to be sensitive to subject motion because of long image acquisition times. To reduce the acquisition time, use of a magnetization‐prepared rapid gradient‐echo (MP‐RAGE) sequence modified for diffusion sensitivity was studied. In this sequence, a preparation phase with a 90°–180°–90° pulse train is used to sensitize the magnetization to diffusion. Centric‐ordered phase encoding, short TRs (5.2–6.5 msec), and small flip angles (5°–8°) are necessary to minimize saturation effects from tissues with short relaxation times. Phantom studies with various concentrations of copper sulfate (T1 ranging from 2,459 to 90 msec) were performed to validate that the diffusion‐weighted signal obtained with the MP‐RAGE sequence was independent of relaxation time. Diffusion‐weighted images of water, isopropyl alcohol, and acetone were acquired to confirm the accuracy of measured diffusion coefficients. Brain images of healthy normal volunteers were obtained to demonstrate motion insensitivity and general image quality of the technique. The results indicate that accurate diffusion‐weighted images can be obtained with a diffusion‐weighted MP‐RAGE sequence, with imaging times of about 1 second.