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Abstract:
Objective
Investigation of the feasibility and performance of phosphorus (31P) magnetic resonance spectroscopic imaging (MRSI) at 9.4 T with a three-layered phosphorus/proton coil in human normal brain tissue and tumor.
Materials and methods
A multi-channel 31P coil was designed to enable MRSI of the entire human brain. The performance of the coil was evaluated by means of electromagnetic field simulations and actual measurements. A 3D chemical shift imaging approach with a variable repetition time and flip angle was used to increase the achievable signal-to-noise ratio of the acquired 31P spectra. The impact of the resulting k-space modulation was investigated by simulations. Three tumor patients and three healthy volunteers were scanned and differences between spectra from healthy and cancerous tissue were evaluated qualitatively.
Results
The high sensitivity provided by the 27-channel 31P coil allowed acquiring CSI data in 22 min with a nominal voxel size of 15 × 15 × 15 mm3. Shimming and anatomical localization could be performed with the integrated four-channel proton dipole array. The amplitudes of the phosphodiesters and phosphoethanolamine appeared reduced in tumorous tissue for all three patients. A neutral or slightly alkaline pH was measured within the brain lesions.
Conclusion
These initial results demonstrate that 31P 3D CSI is feasible at 9.4 T and could be performed successfully in healthy subjects and tumor patients in under 30 min.
