Jiadi Xu1, 2, Nirbhay N. Yadav1, 2, Kannie W.Y. Chan1, 2, Amnon Bar-Shir2, Qin Qin1, 2, Guanshu Liu1, 2, Michael T. McMahon1, 2, Peter C.M. van Zijl1, 2
1F. M. Kirby Center, Kennedy Krieger Institute, Baltimore, MD, United States; 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States
A T2 relaxation dispersion technique is proposed to detect low concentration metabolites with protons that exchange in the intermediate to fast regime on the MR time scale. It employs a Carr-Purcell-Meiboom-Gill (CPMG) pulse train module with a fixed total length. The R2 (1/T2) values measured are dispersed by changing the number of 180 pulses in this module, which varies the pulse spacing. The dispersion curves reflect the concentration, exchange rate, and chemical shift difference of the exchangeable protons with water. The technique easily detects glutamate, myo-inositol and creatine and can quantify their exchange properties.