Advanced

AJNR - American Journal of Neuroradiology

This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Chou, M.-C. Articles by Chen, C.-Y. Search for Related Content PubMed Articles by Chou, M.-C. Articles by Chen, C.-Y.

Pseudolesions Arising from Unfolding Artifacts in Diffusion Imaging with Use of Parallel Acquisition: Origin and Remedies

M.-C. Chou^a,b, C.-Y. Wang^a,b, H.-S. Liu^a,b, H.-W. Chung^a,b and C.-Y. Chen^b

^a Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, ROC
^b Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan, ROC

View larger version (31K): [in this window] [in a new window]   Fig 1. Simulation of parallel imaging at acceleration factor of R = 2 by using perfect/imperfect sensitivity profiles. Image of object (A) was acquired by 2-channel RF coils. Each accelerated raw image (B1 and B2) shows an aliasing pattern due to reduced FOV, which could be unfolded correctly if sensitivity profiles are perfectly obtained (C). With erroneous sensitivity profiles, unfolding artifacts would take place, showing an aliasing pattern spaced at FOV/R from the original object along the phase-encoding direction (D).

View larger version (86K): [in this window] [in a new window]   Fig 2. Sagittal (A) and axial (B) views of the saturation band applied over the eyeball regions to eliminate unfolding pseudolesions in parallel imaging. The saturation band was placed near the borderline of the skull base to avoid accidental suppression of signals from the brain tissue.

View larger version (96K): [in this window] [in a new window]   Fig 3. The b = 0 images (top row) acquired with SENSE parallel imaging at acceleration factors of R = 2, 3, and 4 (left to right columns, respectively) show ghosting from the eyeballs, displaced spatially along the phase-encoding direction at FOV/R, consistent with SENSE unfolding artifacts (first row; arrows). The corresponding b = 1000 diffusion-weighted images exhibit no artifacts (second row), hence resulting in pseudolesion intensity in the ADC and FA maps mimicking diffusion abnormality (third and bottom rows, respectively; arrows).

View larger version (92K): [in this window] [in a new window]   Fig 4. In the same arrangement as Fig. 3, the b = 0 and b = 1000 images, and the ADC and FA maps (top to bottom rows, respectively) obtained with the saturation band to suppress the eyeball signals show no pseudolesions.