Ex-vivo cellular MRI with b-SSFP: quantitative benefits of 3 T over 1.5 T

Introduction The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequ...

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Published in:Magma (New York, N.Y.) N.Y.), 2008-08, Vol.21 (4), p.251-259
Main Authors: Ramadan, Soha Said, Heyn, Chris, MacKenzie, Lisa T., Chambers, Ann F., Rutt, Brian K., Foster, Paula J.
Format: Article
Language:English
Subjects:
Biomedical Engineering and Bioengineering
Computer Appl. in Life Sciences
Health Informatics
Imaging
Iron
Magnetic fields
Medicine
Medicine & Public Health
Radiology
Research Article
Solid State Physics
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Summary:Introduction The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. Methods In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. Results The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. Conclusion There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells.
ISSN:0968-5243
1352-8661
DOI:10.1007/s10334-008-0118-2