Manganese-Enhanced Magnetic Resonance Imaging of the Spinal Cord in Rats

Manganese-enhanced magnetic resonance imaging (MEMRI) offers a novel neuroimaging method in visualizing the activity patterns of neural circuits. MEMRI is using the divalent manganese ion, which has been used as a cellular contrast agent. The present study was conducted to determine the contrast-enhancing effects of manganese ion administered into the spinal cord of rats. Manganese ion was administered into the spinal cord by lumbar puncture. Ex vivo magnetic resonance images were obtained at 6, 12, 24, and 48 hours after manganese ion injection. Although the highly contrasted images were not observed 6 or 12 hr after manganese injection, the distinctive manganese-enhanced images began to appear at 24 hours after manganese ion injection. These results suggest that the gray matter is the foci of intense paramagnetic signals and MEMRI may provide an effective technique to visualize the activity-dependent patterns in the spinal cord.

Evaluations of Spectral Analysis of in vitro 2D-COSY and 2D-NOESY on Human Brain Metabolites

PURPOSE: To investigate the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar nuclear Overhauser effect/enhancement (NOE) interaction through 2D- correlation spectroscopy (COSY) and 2D- NOE spectroscopy (NOESY) techniques. MATERIALS AND METHODS: All 2D experiments were performed on Bruker Avance 500 (11.8 T) with the zshield gradient triple resonance cryoprobe at 298 K. Human brain metabolites were prepared with 10% D2O. Two-dimensional spectra with 2048 data points contains 320 free induction decay (FID) averaging. Repetition delay was 2 sec. The Top Spin 2.0 software was used for post-processing. Total 7 metabolites such as N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), glutamine (Gln), glutamate (Glu), myo-inositol (Ins), and lactate (Lac) were included for major target metabolites. RESULTS: Symmetrical 2D-COSY and 2D-NOESY spectra were successfully acquired: COSY cross peaks were observed in the only 1.0-4.5 ppm, however, NOESY cross peaks were observed in the 1.0-4.5 ppm and 7.9 ppm. From the result of the 2-D COSY data, cross peaks between the methyl protons (CH3(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methylene protons (CH2(3,H alpha)) at 2.50ppm and methylene protons (CH2,(3,HB)) at 2.70 ppm were observed in NAA. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. From the result of 2-D NOESY data, cross peaks between the NH proton at 8.00 ppm and methyl protons (CH3) were observed in NAA. Cross peaks between the methyl protons (CH3(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methyl protons (CH3) at 3.03 ppm and methylene protons (CH2) at 3.93 ppm were observed in Cr. Cross peaks between the methylene protons (CH2(3)) at 2.11 ppm and methylene protons (CH2(4)) at 2.35 ppm, and between the methylene protons(CH2 (3)) at 2.11 ppm and methine proton (CH(2)) at 3.76 ppm were observed in Glu. Cross peaks between the methylene protons (CH2 (3)) at 2.14 ppm and methine proton (CH(2)) at 3.79 ppm were observed in Gln. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. CONCLUSION: The present study demonstrated that in vitro 2D-COSY and NOESY represented the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar NOE interaction. This study could aid in better understanding the interactions between human brain metabolites in vivo 2DCOSY study.