Optimization of pulse sequences for lactate detection using MR spectroscopy

Objective: To obtain the optimal detection and quantitative analysis of lactate by changing a series of parameters used in the MR pulse sequences. Methods: A glass model containing lactate was utilized. The MR scanner was a 1.5 T system (Signa MR/i, GE). After using the fast gradient echo sequence to define the position of volume of interest (VOI), the spectra were obtained by using both PRESS and STEAM sequences. The experiment was also carried out in 12 patients with brain diseases and two volunteers. Three voxels (2 cm x 2 cm x 2 cm) were placed in external standard solution and the corresponding locations of the encephalopathy, respectively. The peak heights were measured after the baselines were corrected. The curves of the peak heights versus the TE were plotted using EXCEL program. Results: The curves of lactate peaks versus TE obtained by the model using PRESS and STEAM sequences exhibited waveform characteristic. The up-doublets were recorded with their maximum peak heights using TE values of 26 ms and 270 ms,whereas the down-doublets were recorded at their peaks using a TE value between 135 to 160 ms. All the peaks recorded by STEAM sequence were similar to those recorded by PRESS sequence. However, the former were weaker than the latter. The results indicated that the optimized sequences were useful for better detection of lactate in clinical examinations. Conclusion: The optimized sequences are able to benefit the detection and quantitative analysis of lactate. (authors)