The role of relaxation time corrections for the evaluation of long and short echo time 1H MR spectra of the hippocampus by NUMARIS and LCModel techniques.
ABSTRACT 1H MR spectroscopy is routinely used for lateralization of epileptogenic lesions. The present study deals with the role of relaxation time corrections for the quantitative evaluation of long (TE=135 ms) and short echo time (TE=10 ms) 1H MR spectra of the hippocampus using two methods (operator-guided NUMARIS and LCModel programs). Spectra of left and right hippocampi of 14 volunteers and 14 patients with epilepsy were obtained by PRESS (TR/TE=5000/135 ms) and STEAM (TR/TE=5000/10 ms) sequences with a 1.5-T imager. Evaluation was carried out using Siemens NUMARIS software and the results were compared with data from LCModel processing software. No significant differences between the two methods of processing spectra with TE=135 ms were found. The range of relaxation corrections was determined. Metabolite concentrations in hippocampi calculated from spectra with TE=135 ms and 10 ms after application of correction coefficients did not differ in the range of errors and agreed with published data (135 ms/10 ms: NAA=10.2+/-0.6/10.4+/-1.3 mM, Cho=2.4+/-0.1/2.7+/-0.3 mM, Cr=12.2+/-1.3/11.3+/-1.3 mM). When relaxation time corrections were applied, quantitative results from short and long echo time evaluation with LCModel were in agreement. Signal intensity ratios obtained from long echo time spectra by NUMARIS operator-guided processing also agreed with the LCModel results.
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ABSTRACT: In this study, short echo time (1)H-magnetic resonance spectroscopy (MRS) was applied for quantification of neurometabolites using the LC Model algorithm in Taiwanese adolescents with attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectra were acquired bilaterally on the prefrontal area (part of the anterior cingulate gyrus and part of the medial frontal gyrus) in 15 adolescents with ADHD (average age of 13.88years) and 22 controls (average age of 14.85years). Absolute metabolite levels and ratios relative to creatine plus phosphocreatine (Cr+PCr) were obtained to be compared between groups. Results showed that adolescents with ADHD had significantly lower mean right prefrontal levels of Cr+PCr as compared with the controls. No significant differences between groups were noted in the remainder of the prefrontal metabolites. As for the group comparison of relative ratios, the N-acetylaspartate/Cr+PCr ratio was significantly higher in the right prefrontal regions of ADHD adolescents. This finding provides evidence of a right prefrontal neurochemical alteration in ADHD adolescents, which is consistent with current ADHD theory of prefrontal neuropathology with developmental mechanism. In addition, it highlights the importance of the method in interpretation of MRS findings in the context of ADHD.Psychiatry Research 02/2010; 181(3):199-203. · 2.68 Impact Factor
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ABSTRACT: The influence of iron deposits on T2 values and the content of metabolites in the brain of three patients with DNA proved pantothenate kinase-associated neurodegeneration (PKAN, formerly Hallervorden-Spatz syndrome) was studied. An eye-of-the-tiger sign, a typical MR finding for PKAN, was observed in two patients with the same mutation. A hypointensive lesion in a whole globus pallidus was observed in the third patient with the additional mutation. T2 values in the globus pallidus of the patients were about 40% shorter than in controls (71/48 ms in controls vs. patients), which corresponds to the increase of Fe concentration based on the ferritin basis from 17 mg for controls to 48 mg (100 g wet brain weight) in PKAN patients. 1H MR spectroscopy (MRS) has mainly been used to describe neuronal damage represented by decreased NAA (6.4 mmol vs. 9 mmol) and Cr/PCr (7.0 mmol vs. 9.8 mmol) concentrations in the basal ganglia region of the patient group to controls; MRS is much more case-sensitive and describes individual development of the disease as demonstrated in the difference between the spectra of typical PKAN patients (1, 2), and the patient (3) with atypical PKAN development. Any significant changes of metabolite concentration with the exception glutamine, glutamate and GABA were found in the white matter.European Radiology 06/2005; 15(5):1060-8. · 4.34 Impact Factor
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ABSTRACT: PurposeTo introduce a method of independent determination of CH2 and CH3 components of intramyocellular lipids (IMCLs) by using long TE for spectra measurement and LCModel for spectra evaluation, to test this technique in controls and insulin-resistant subjects, and to compare results at 1.5 and 3 T.Materials and Methods Eight healthy volunteers and 11 patients with type 2 diabetes mellitus underwent measurement using a 1.5-T MR scanner; six healthy volunteers were measured using a 3-T MR scanner. Spectra from the tibialis anterior muscle were acquired by using a point resolved spectroscopy (PRESS) sequence with the following parameters: TR/TE/ACQ = 2000 msec/270 msec/256. Spectra were processed by LCModel 6.1 software with two types of adopted basis-set.ResultsSpectra with good separation of both CH2 and CH3 components of IMCL and extramyocellular lipids (EMCLs) were obtained and the LCModel routine was successfully applied. The reproducibility comparison (N= 7 at 1.5 T vs. N = 5 at 3 T) showed that better results can be obtained at higher B0 values. The comparison of the healthy and insulin-resistant subjects proved that both IMCL_CH2/Cr and IMCL_CH3/Cr ratios significantly differ.Conclusion Long TE spectroscopy of the human muscle with IMCL quantification using the LCModel technique can detect changes in IMCL levels as well as help in the study of fatty acyl chain composition. Using a higher field strength increased the intra-individual reproducibility by approximately 150% J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.Journal of Magnetic Resonance Imaging 03/2006; 23(5):728 - 735. · 2.57 Impact Factor