Fast multislice pH-weighted chemical exchange saturation transfer (CEST) MRI with Unevenly segmented RF irradiation.
Chemical exchange saturation transfer (CEST) MRI is a versatile imaging technique for measuring microenvironment properties via dilute CEST labile groups. Conventionally, CEST MRI is implemented with a long radiofrequency irradiation module, followed by fast image acquisition to obtain the steady state CEST contrast. Nevertheless, the sensitivity, scan time, and spatial coverage of the conventional CEST MRI method may not be optimal. Our study proposed a segmented radiofrequency labeling scheme that includes a long primary radiofrequency irradiation module to generate the steady state CEST contrast and repetitive short secondary radiofrequency irradiation module immediately after the image acquisition so as to maintain the steady state CEST contrast for multislice acquisition and signal averaging. The proposed CEST MRI method was validated experimentally with a tissue-like pH phantom and optimized for the maximal contrast-to-noise ratio. In addition, the proposed sequence was evaluated for imaging ischemic acidosis via pH-weighted endogenous amide proton transfer MRI, which showed similar contrast as conventional amide proton transfer MRI. In sum, a fast multislice relaxation self-compensated CEST MRI sequence was developed, with significantly improved sensitivity and suitable for in vivo applications.
Sun
Phillip Zhe
PZ
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA. pzhesun@nmr.mgh.harvard.edu
Cheung
Jerry S
JS
Wang
Enfeng
E
Benner
Thomas
T
Sorensen
A Gregory
AG
D000818:Animals; D003287:Contrast Media; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D011846:Radio Waves; D051381:Rats; D017208:Rats, Wistar; D020521:Stroke / Q000175:diagnosis
D003287:Contrast Media