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OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder (MDD). This study evaluated the antidepressant effect of rTMS and examined how it affected N-asetyl aspartate (NAA), choline (Cho), creatine (Cr), lactate (Lac), myoinositol (mIns), glutamate (Glu), glutathione (GSH), and glutamine (Gln) metabolite levels in the left dorsolateral prefrontal cortex (DLPFC) of MDD patients who were not receiving antidepressant medication. METHODS: In total, 18 patients (10 female, 8 male) were evaluated. Each patient underwent H magnetic resonance spectroscopy (H-MRS) before and within 3 days of completion of TMS therapy. All patients completed 20 sessions of rTMS directed at the left DLPFC over a 2-week period. The Hamilton Depression Scale (HAMD) scores of patients were calculated, and their responses to treatment were assessed within 1–3 days of completion of TMS. RESULTS: We found statistically significant differences in HAMD scores before and after rTMS. Moreover, the peak metabolite ratios of NAA/Cr, GSH/Cr, and Gln/Cr were significantly higher after rTMS compared to those before rTMS. CONCLUSION: Increased understanding of the mechanism of action of TMS will improve its application and may stimulate development of new-generation therapeutic agents.
Subject(s)
Female , Humans , Aspartic Acid , Choline , Creatine , Depression , Depressive Disorder, Major , Glutamic Acid , Glutamine , Glutathione , Inositol , Lactic Acid , Magnetic Resonance Spectroscopy , Prefrontal Cortex , Transcranial Magnetic StimulationABSTRACT
Chemical exchange saturation transfer (CEST) is a novel MRI technology developed in recent years. In CEST, the exchangeable hydrogen protons were saturated using a selective RF pulse, and then transferred into free water by chemical exchange. This process leads to a reduction of free pool signal, which can be used to infer the solute pool information and environmental information around the solute. In recent years, CEST technology has developed rapidly, and various CEST contrast agents have been developed with their own characteristics and applications. In this review paper, the principles, measurement of CEST signal, types of CEST agents, and the applications of several commonly used CEST contrast agents in human brain imaging researches were introduced including amide proton transfer imaging CEST (APT-CEST), glutamate CEST (gluCEST) and glucose CEST (glucoCEST).
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Objective To detect the metabolites of non-motor functional area in patients with Parkinson disease (PD) by proton magnetic resonance spectroscopy (1H-MRS).Methods Forty-two PD patients (PD group) tested with unified PD rating scale (UPDRS) and 20 healthy controls(normal control group) were enrolled in this study.MRI and 1H-MRS using a GE signa excite1.5T MR was obtained,and the ratios of metabolites such as N-acetylaspartate(NAA)/creatin(Cr),NAA/cholinecompounds(Cho) in the prefrontal lobe,hippocampus,cuneus gyrus and dorsal thalamus were compared.Correlations between brain metabolites and UPDRS were analyzed.Results The levels of NAA/Cr,and NAA/Cho in bilateral dorsal thalamus,cuneus gyrus,hippocampus,prefrontal lobe in PD group were significantly lower than those in normal control group (P ＜ 0.01).The level of Cho/Cr in right hippocampus,right cuneus gyms,and right dorsal thalamus in PD group was significantly higher than that in normal control group (P ＜ 0.05).The NAA/Cho in the left hippocampus (r =-0.388,P =0.011) and left cuneus gyrus (r =-0.325,P =0.036) was negatively correlated with UPDRS scores (P ＜ 0.05).Conclusions There is extensive neuronal damage and some glial proliferation in the non-motor functional areas including prefrontal lobe,hippocampus,cuneus gyrus,anddorsal thalamus in the PD patients.The degree of damage in left hippocampus and left cuneus gyms is positively correlated with the severity of the disease clinically.
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Objective By 1 H magnetic resonance spectroscopy( 1 H MRS) ,small for gestational age (SGA)and appropriate for gestational age(AGA) as the detection of brain metabolites and MRI plus soft-ware measurement in different brain areas of volume,investigate its cerebral metabolites and the changes of brain in different parts of the volume and significance. Methods Select 88 patients eligible infants, SGA group of 27 cases and AGA group of 21 cases of premature infants;SGA group of 22 cases and AGA group of 18 cases of term infants. Preterm infants with a gestational age of 32 to 36 weeks,term infants with a gesta-tional age of 37 to 41 weeks. Check time between 4 to 7 days old. Calculation of cerebrum volume,cerebellar volume and cerebrospinal fluid volume and intracranial volume,N-acetylaspartic acid(NAA),as 1H MRS area of metabolites measured right frontal choline compounds( Cho) and creatine compounds( Cr) wave,calcu-lation of Cho/Cr and NAA/Cho ratio of NAA/Cr. Results NAA/Cr,the cerebrum volume and intracranial volume of SGA in premature infants group,term infants group and mixed group were 0. 627 ± 0. 183,(2. 831 ±0. 199) ×105 mm3,(3. 178 ±0. 209) ×105 mm3;0. 706 ±0. 139,(3. 056 ±0. 217) ×105 mm3,(3. 411 ± 0. 212 ×105 mm3;0. 708 ± 0. 171,(2. 932 ± 0. 234) × 105 mm3,(3. 282 ± 0. 239) × 105 mm3,respective-ly. NAA/Cr,the cerebrum volume and intracranial volume of AGA in premature infants group,term infants group and mixed group were 0. 734 ± 0. 101,(2. 987 ± 0. 111) × 105 mm3,(3. 347 ± 0. 137) × 105 mm3;0. 805 ± 0. 106, ( 3. 228 ± 0. 284 ) × 105 mm3 , ( 3. 588 ± 0. 306 ) × 105 mm3; 0. 721 ± 0. 119, ( 3. 098 ± 0.240) ×105 mm3,(3.458 ±0.258) ×105 mm3,respectively. The data of SGA group were all lower than those in AGA group,which had significant difference(P0. 05,respectively). In the premature infants groups,the NAA/Cho of SGA group(0. 401 ± 0. 737) was lower than in the AGA group(0. 506 ± 0. 116), which had significant difference(P=0. 000). In the term infants groups,the NAA/Cho of SGA group(0. 483 ±0. 605) was lower than in the AGA group(0. 472 ± 0. 987),which had no significant difference(P =0. 653). In the AGA groups,NAA/Cr,NAA/Cho,cerebellar volume and cerebrospinal fluid volume of pre-mature infants group and term infants group had no significant difference ( P>0. 05 ) . Both of the cerebellar volume and cerebrospinal fluid volume between the premature infants AGA group and premature infants AGA group had no significant difference(P>0. 05). Conclusion Neurons in the brain,the cerebrum volume,the cranial cavity volume and NAA/Cr of SGA was significantly lower than those of AGA,but Cho/Cr,cerebel-lar volume and cerebrospinal fluid volume of SGA and AGA had no significant difference. NAA/Cr in the brain and the cerebrum volume of SGA may be associated with low volume of small nerve mental retarda-tion,worthy of further study.
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INTRODUCTION: The intrinsically high sensitivity of Magnetic Resonance Spectroscopy (MRS) causes considerable variability in metabolite quantification. In this study, we evaluated the variability of MRS in two research centers using the same model of magnetic resonance image scanner. METHODS: Two metabolic phantoms were created to simulate magnetic resonance spectra from in vivo hippocampus. The phantoms were filled with the same basic solution containing the following metabolites: N-acetyl-aspartate, creatine, choline, glutamate, glutamine and inositol. Spectra were acquired over 15 months on 26 acquisition dates, resulting in a total of 130 spectra per center. RESULTS: The phantoms did not undergo any physical changes during the 15-month period. Temporal analysis from both centers showed mean metabolic variations of 3.7% in acquisitions on the same day and of 8.7% over the 15-month period. CONCLUSION: The low deviations demonstrated here, combined with the high specificity of Magnetic Resonance Spectroscopy, confirm that it is feasible to use this technique in multicenter studies in neuroscience research.
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The technology of Magnetic Resonance Spectroscopy(MRS) is a newly-developed mean for analyzing some specific nucleus and their compounds making use of the principles of magnetic resonance and the effects of chemical shift. Currently, among MRS applications, proton magnetic resonance spectroscopy (1HMRS) is the most widely applied one developed from single voxel to three-dimensional multi-voxel scanning technique. It provides a lot of important information for clinical studies. This article mainly reviews the methods for absolute quantification measurement of brain metabolites using multi-voxel MRS.
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Background & objectives: Repeated apnoeic/hypoapnoeic episodes during sleep may produce cerebral damage in patients with obstructive sleep apnoea (OSA). The aim of this study was to determine the absolute concentration of cerebral metabolites in apnoeic and non-apnoeic subjects from different regions of the brain to monitor the regional variation of cerebral metabolites. Methods: Absolute concentration of cerebral metabolites was determined by using early morning proton magnetic resonance spectroscopy (1H MRS) in 18 apnoeic patients with OSA (apnoeics) having apnoea/hypopnoea index (AHI) >5/h, while 32 were non-apnoeic subjects with AHI< 5/h. Results: The absolute concentration of tNAA [(N-acetylaspartate (NAA)+N-acetylaspartylglutamate (NAAG)] was observed to be statistically significantly lower (P<0.05) in apnoeics in the left temporal and left frontal gray regions compared to non-apnoeics. The Glx (glutamine, Gln + glutamate, Glu) resonance showed higher concentration (but not statistically significant) in the left temporal and left frontal regions of the brain in apnoeics compared to non-apnoeics. The absolute concentration of myo-inositol (mI) was significantly high (P<0.03) in apnoeics in the occipital region compared to non-apnoeics. Interpretation & conclusions: Reduction in the absolute concentration of tNAA in apnoeics is suggestive of neuronal damage, probably caused by repeated apnoeic episodes in these patients. NAA showed negative correlation with AHI in the left frontal region, while Cho and mI were positively correlated in the occipital region and Glx showed positive correlation in the left temporal region of the brain. Overall, our results demonstrate that the variation in metabolites concentrations is not uniform across various regions of the brain studied in patients with OSA. Further studies with a large cohort of patients to substantiate these observations are required.