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Comparative Study
. 2009 Jan;27(1):13-22.
doi: 10.1016/j.mri.2008.05.009. Epub 2008 Jul 22.

HASTE sequence with parallel acquisition and T2 decay compensation: application to carotid artery imaging

Ling Zhang  1 , Eugene G Kholmovski, Junyu Guo, Seong-Eun Kim Choi, Glen R Morrell, Dennis L Parker
Affiliations
Comparative Study

HASTE sequence with parallel acquisition and T2 decay compensation: application to carotid artery imaging

Ling Zhang et al. Magn Reson Imaging. 2009 Jan.

Abstract

T2-weighted carotid artery images acquired using the turbo spin-echo (TSE) sequence frequently suffer from motion artifacts due to respiration and blood pulsation. The possibility of using HASTE sequence to achieve motion-free carotid images was investigated. The HASTE sequence suffers from severe blurring artifacts due to signal loss in later echoes due to T2 decay. Combining HASTE with parallel acquisition (PHASTE) decreases the number of echoes acquired and thus effectively reduces the blurring artifact caused by T2 relaxation. Further improvement in image sharpness can be achieved by performing T2 decay compensation before reconstructing the PHASTE data. Preliminary results have shown successful suppression of motion artifacts with PHASTE imaging. The image quality was enhanced relative to the original HASTE image, but was still less sharp than a non-motion-corrupted TSE image.

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Figures

Fig. 1
Fig. 1
Illustration of the PHASTE data reconstruction where the denser sampling is around the center of k-space. (a) The k-space sampling pattern for PHASTE with R=2. (b) The k-space data after KIPA was used to recover the missing PE views (dashed lines). (c) The complete k-space corresponding to the image obtained after applying Homodyne reconstruction to the data in (b).
Fig. 2
Fig. 2
Comparison of energy spectrum for different pulse sequences. (a) Energy spectrum for TSE (gray line) and HASTE (dark line). (b) Energy spectrum for TSE and PHASTE with R=2 (dark line).
Fig. 3
Fig. 3
Illustration of T2 compensation function construction. (a) Function D calculated from the data without PE. (b) Inversion of function D with the minimum normalized to 1. (c) The sum of Gaussian function (σ=128/3) with a factor β=0.01. (d) The final T2 compensation function obtained by multiplying the functions shown in (b) and (c).
Fig. 4
Fig. 4
Phantom study. (a) HASTE image without T2 compensation. (b) PHASTE image without T2 compensation, R=2. (c) HASTE image with T2 compensation. (d) PHASTE image with T2 compensation, R=2.
Fig. 5
Fig. 5
Result of the first human carotid study. (a) HASTE image without T2 compensation. (b) PHASTE image without T2 compensation. (c) TSE image. (d) PHASTE image with T2 compensation.
Fig. 6
Fig. 6
Result of the second human carotid study. (a) T2-compensated PHASTE images for different slices with different slice thickness (3 mm for the top 2 images and 2 mm for the bottom image). (b) TSE images for the same slices.
Fig. 7
Fig. 7
Comparison of T2 weighted TSE images (left column) with T2-compensated PHASTE images (right column). Top two rows are from a single subject with minimal motion artifact. Bottom row is from a subject with substantial motion artifact. Thin arrows point to carotid artery with plaque. Fat arrows point to carotid artery obscured by the motion artifact.
See this image and copyright information in PMC

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