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Fast diffusion‐weighted steady state free precession imaging of in vivo knee cartilage
Author(s) -
Bieri O.,
Ganter C.,
Welsch G. H.,
Trattnig S.,
Mamisch T. C.,
Scheffler K.
Publication year - 2012
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.23061
Subject(s) - flip angle , steady state free precession imaging , precession , nuclear magnetic resonance , diffusion , steady state (chemistry) , physics , attenuation , diffusion mri , signal to noise ratio (imaging) , signal (programming language) , transverse plane , chemistry , magnetic resonance imaging , optics , condensed matter physics , computer science , medicine , anatomy , radiology , programming language , thermodynamics
Quantification of molecular diffusion with steady state free precession (SSFP) is complicated by the fact that diffusion effects accumulate over several repetition times (TR) leading to complex signal dependencies on transverse and longitudinal magnetization paths. This issue is commonly addressed by setting TR > T 2 , yielding strong attenuation of all higher modes, except of the shortest ones. As a result, signal attenuation from diffusion becomes T 2 independent but signal‐to‐noise ratio (SNR) and sequence efficiency are remarkably poor. In this work, we present a new approach for fast in vivo steady state free precession diffusion‐weighted imaging of cartilage with TR << T 2 offering a considerable increase in signal‐to‐noise ratio and sequence efficiency. At a first glance, prominent coupling between magnetization paths seems to complicate quantification issues in this limit, however, it is observed that diffusion effects become rather T 2 (Δ D ∼ 1/10 Δ T 2 ) but not T 1 independent (Δ D ∼ 1/2 Δ T 1 ) for low flip angles α ∼ 10 − 15°. As a result, fast high‐resolution (0.35 × 0.35 − 0.50 × 0.50 mm 2 in‐plane resolution) quantitative diffusion‐weighted imaging of human articular cartilage is demonstrated at 3.0 T in a clinical setup using estimated T 1 and T 2 or a combination of measured T 1 and estimated T 2 values. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.