New method for contrast manipulation in DNP-enhanced MRI.
The magnetization subtraction technique (MS), which is equivalent to the inversion recovery technique in strong magnetic fields, has been implemented in dynamic nuclear polarization-enhanced magnetic resonance imaging (DNPI). The general theoretical basis of the MS method, which can be applied to DNPI or to prepolarized MRI in weak magnetic fields (such as Earth's magnetic field), is introduced. Details are provided about the signal amplitude, dynamic range of the method, and conditions required to observe signal void in samples with specific T1 relaxation times. The experimental results obtained with MS DNPI are presented and discussed. In the experiments, electron spin resonance irradiation frequencies of 199 MHz and 16.2 MHz were employed. Also, T1 contrast manipulation in the polarizing and in the detection magnetic field is discussed and demonstrated for MS DNPI.
Planinsic
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G
Fakulteta za matematiko in fiziko, Univerza v Ljubljani, Ljubljana, Slovenia.
Grucker
D
D
Stepisnik
J
J
D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D019047:Phantoms, Imaging; D013382:Subtraction Technique