In Vivo 3D Localized ¹³C Spectroscopy Using Modified INEPT and DEPT

The 3D localized ¹³C spectroscopy methods LINEPT and LODEPT, which are modifications of INEPT and DEPT, are proposed. As long as a ¹³C inversion pulse (180-degree pulse) is applied at 1/(4J) before the proton echo time in LINEPT and a ¹³C excitation pulse (90-degree pulse) is applied at 1/(2J) before the proton echo time in LODEPT, the proton echo time can be set to any value longer than 1J(2J) in LINEPT and longer than 1/J in LODEPT. As a result, the proton and the ¹³C pulses can be applied separately and these proton pulses can be made slice-selective pulses. These localization features of LINEPT and LODEPT were evaluated using a phantom consisting of a cylinder filled with ethanol placed inside another cylinder filled with oil, and localized ethanol spectra could be obtained. In vivo 3D localized ¹³C spectra from the brain of a monkey could be obtained using decoupled LINEPT, and glutamate C-4 appeared directly after the administration of glucose C-1, followed by the appearance of glutamate C-2, C-3 and glutamine C-2, C-3, C-4.