Purpose: (i) To develop an MRS technique to measure 7Li levels in human brain in a reasonable scan time, (ii) to develop a technique to quantify 7Li T2 relaxation times as measured from human brain in patients taking lithium for the treatment of their bipolar disorder, and (iii) to confirm or refute the presence of bi-exponential 7Li T2 relaxation in human brain. Materials and Methods: We modified a spin-echo MRS pulse sequence to decrease its minimum echo time. With IRB approval, we performed lithium MRS with the modified pulse sequence on 13 euthymic bipolar patients stable on long-term lithium to treat their disease. Results: We were able to achieve a total scan time per sample of 8:20; total scan time including imaging, calibration and MRS was approximately 1 h 15 min. We observed bi-exponential T2 relaxation in the majority of patients, with an average short decay time of 5.3 ± 1.4 ms and an average long decay time of 68.2 ± 10.2 ms. However, in two patients we observed strongly mono-exponential T2 relaxation with an average decay time of 47.4 ± 1.3 ms. Conclusion: 7Li relaxation patterns may prove useful to distinguish between lithium-responsive and lithium nonresponsive bipolar patients.
- T2 relaxation
- bipolar disorder
- magnetic resonance spectroscopy
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging