Brain lithium concentrations in bipolar disorder patients: preliminary (7)Li magnetic resonance studies at 3 T.
BACKGROUND
This study was conducted to investigate the feasibility of human brain (7)Li MRS investigations at a high magnetic field (3 T), and to further explore the relationship between brain and serum lithium measures in lithium-treated bipolar patients.


METHODS
Eight bipolar disorder type I patients (5 males, 3 females; mean age +/- SD = 33 +/- 9 years) were studied. A 3-T scanner, using a dual-tuned ((1)H and (7)Li) echoplanar imaging (EPI) compatible radiofrequency (RF) birdcage coil was used. (7)Li magnetic resonance spectroscopy (MRS) signal was acquired at the frequency of 49.64 MHz using an imaging selective in vivo spectroscopy (ISIS) sequence (TR = 15 sec, 128 averages), and quantitation was obtained in reference to an external standard.


RESULTS
The mean +/- SD oral lithium dose was 1265 +/- 442 mg/day, and the mean +/- SD 12-hour serum level was 0.69 +/- 0.19 mEq/L. The measured brain lithium concentrations varied from 0.23 to 0.55 mEq/L (mean +/- SD = 0.35 +/- 0.11 mEq/L). The brain-serum ratios varied from 0.30 to 0.80 (mean +/- SD = 0.52 +/- 0.16). Subjects on single daily doses of lithium at bedtime (n = 5) had higher brain-serum lithium ratios compared with those on twice-a-day schedules (n = 3) (0.61 +/- 0.12 and 0.37 +/- 0.07, respectively; Mann--Whitney U test, Z = -2.24, p =.03).


CONCLUSIONS
This study demonstrated for the first time the feasibility of (7)Li MRS human studies at 3 T. Future studies should examine a possible role for this methodology in investigations of lithium refractoriness and prediction of treatment outcome in bipolar patients.
Soares
J C
JC
Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
Boada
F
F
Spencer
S
S
Mallinger
A G
AG
Dippold
C S
CS
Wells
K F
KF
Frank
E
E
Keshavan
M S
MS
Gershon
S
S
Kupfer
D J
DJ
D000328:Adult; D018692:Antimanic Agents / Q000097:blood / Q000493:pharmacokinetics*; D001714:Bipolar Disorder / Q000378:metabolism*; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008094:Lithium / Q000097:blood / Q000493:pharmacokinetics*; D009682:Magnetic Resonance Spectroscopy; D008297:Male
D018692:Antimanic Agents; D008094:Lithium