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Time‐resolved MR angiography with limited projections
Author(s) -
Huang Yuexi,
Wright Graham A.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21312
Subject(s) - computer science , contrast (vision) , signal (programming language) , angiography , artificial intelligence , gadolinium , magnetic resonance angiography , computer vision , nuclear medicine , magnetic resonance imaging , radiology , materials science , medicine , metallurgy , programming language
A method for reconstruction of time‐resolved MRI called highly‐constrained backprojection (HYPR) has been developed. To evaluate the HYPR reconstruction in relation to data sparsity and temporal dynamics, computer simulations were performed, investigating signal modulations under different situations that reflect dynamic contrast‐enhanced MR angiography (MRA). In vivo studies were also performed with gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) for abdominal MRA in a canine model to demonstrate the application of HYPR for three‐dimensional (3D) time‐resolved MRA. When contrast dynamics vary over space, large vessels (e.g., veins) tend to introduce signal interference to small vessels (e.g., arteries) in HYPR, particularly when the vessels are in close proximity. The enhancement of background tissue signals may also alter the arterial and venous temporal profiles in HYPR. However, the artifacts are manifest as intensity modulation rather than structural interference, and therefore have little impact on structural diagnosis. Increasing the number of projections per time point increases temporal blur while reducing corruption of temporal behavior from adjacent tissues. Uniformly interleaved acquisition order, such as the bit‐reversed order, is important to reduce artifacts. With high signal‐to‐noise ratio (SNR) and limited artifacts, HYPR reconstruction has potential to greatly improve time‐resolved MRA in clinical practice. Magn Reson Med 58:316–325, 2007. © 2007 Wiley‐Liss, Inc.