Fast magnetization transfer and apparent T1 imaging using a short saturation pulse with and without inversion preparation. Issue 3 (19th April 2013)

• Record Type: Journal Article
• Authors: Kim, Tae; Shin, Wanyong; Kim, Seong‐Gi
• Is Part Of: Magnetic resonance in medicine. Volume 71:Issue 3(2014:Mar.)
• Page Start: 1264
• Page End: 1271
• Publication Date: 2013-04-19
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.24756
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm24756-sec-0001" sec-type="section"> <title>Purpose</title> <p>Measurements of magnetization transfer (MT) metrics, such as the steady‐state (SS) MT ratio and apparent longitudinal relaxation rate require multiple MT irradiation durations and a long experimental time. To overcome these problems, we propose a novel method using a short MT off‐resonance pulse with and without on‐resonance inversion preparation pulse.</p> </sec> <sec id="mrm24756-sec-0002" sec-type="section"> <title>Theory and Methods</title> <p>Computer simulations were performed to examine the accuracy of the proposed method and to find the optimal off‐resonance irradiation pulse duration (<italic>T</italic><sub>irad</sub>) and power level (<italic>ω</italic><sub>1</sub>). Our approach, with echo planar imaging data acquisition, was applied to animals at 9.4 T and humans at 3 T with <italic>ω</italic><sub>1</sub>/2π = 100 Hz and 177 Hz, respectively. Steady‐state MT ratio and relaxation rate were obtained from a pair of MT images at a <italic>T</italic><sub>irad</sub>, with and without inversion.</p> </sec> <sec id="mrm24756-sec-0003" sec-type="section"> <title>Results</title> <p>For <italic>T</italic><sub>irad</sub> ≥ 0.4 s, steady‐state MT ratio, and relaxation rate measured at any single <italic>T</italic><sub>irad</sub> agreed well with those of the conventional fitting method that uses multiple <italic>T</italic><sub>irad</sub>. Our simulation indicates that a higher <italic>ω</italic><sub>1</sub> can use a shorter Tirad.</p> </sec> <sec id="mrm24756-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Steady‐state MT ratio and relaxation rate can be determined from MT data with only one, short <italic>T</italic><sub>irad</sub> by incorporation of an inversion prepulse. This MT imaging approach is simple, fast, and easily implementable. <bold>Magn Reson Med 71:1264–1271, 2014. © 2013 Wiley Periodicals, Inc</bold>.</p> </sec> </abstract>