期刊
NMR IN BIOMEDICINE
卷 21, 期 1, 页码 59-70出版社
JOHN WILEY & SONS LTD
DOI: 10.1002/nbm.1179
关键词
short-T-2; cortical bone; radial imaging; half-pulse; bone water
资金
- NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES [R01AR049553, R01AR050068] Funding Source: NIH RePORTER
- NIAMS NIH HHS [R01 AR 50068, R01 AR 49553] Funding Source: Medline
Water in dense collagenous tissues such as tendons and ligaments, as well as water in cortical bone that occupies the spaces of the lacuno-canicular system or is tightly bound to collagen, is not ordinarily detectable by MRI. Water proton T-2 in these structures is generally less than 1 ms. Recent advances in instrumentation in conjunction with non-Cartesian imaging strategies now allow center of k-space to be scanned 100 mu s or less after excitation. We examined the performance of two radial pulse sequences, a 2D sequence with half-pulse excitation and a new 3D hybrid sequence with variable-echo Cartesian encoding in the third dimension, on a whole-body 3 T scanner. Both pulse sequences used long-T-2 soft-tissue suppression pulses. The half-pulse slice profiles observed experimentally agreed well with those computed on the basis of a numerical solution of Bloch equations. The techniques yielded a signal-to-noise ratio of the order of 25 in 9 min scan time at a nominal voxel size of 0.58 x 0.58 x 8 mm(3) and 50-90 mu s 'echo time' in the cortex of the tibial mid-shaft. With the use of an external reference, the water volume fraction of cortical bone in four subjects (mean +/- SD age 32.25 +/- 5.3 years) was found to be 22.5 +/- 2.7%, in good agreement with literature values. Copyright (c) 2007 John Wiley & Sons, Ltd.
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