64, 3.5, 5.36, 7.22, 9.08] msec, TR = 2.53 sec, T1 = 1.2 sec, flip angle = 7°, slice thickness = 1 mm and resolution = 256 × 256 mm2 was used to prescribe a single 12 cc (20 × 20 × 30 mm3) 1H-MRS voxel in the anterior cingulate region of the brain. Data were collected with body coil excitation,

in conjunction with head matrix coils in receive mode, using a PRESS sequence with TR/TE = 1.5 sec/40 msec, 1600-Hz bandwidth and 192 averages. Scanner preprocessing software corrects zero-order phase differences before combining individual spectra from different channels Inhibitors,research,lifescience,medical (Natt et al. 2005), averages acquisitions from multiple scans, and saves acquired data in 1024 complex time-domain data points. Inhibitors,research,lifescience,medical For use with LCModel, a water spectrum with 16 averages was also acquired from the same voxel. In the ICA analysis, we used water-suppressed data, which had been normalized by the scanner software using a single scan water reference acquisition (Natt et al. 2005). As ICA works collectively on all spectra,

Inhibitors,research,lifescience,medical data from all subjects were read and stored in a matrix. Also, as our ICA approach requires complex, frequency-domain data, the acquired complex time-domain data were converted into spectral domain using FFT. In vivo spectra were corrected for B0 variation by using real part of the N-acetyl peak of NAA spectrum from LCModel basis to align spectra. Following spectral alignment, we sought to exclude spectra that could unduly bias component estimation and extraction. Spectra with suspect LCModel results, such as those with large full-width half-maximum (FWHM > 0.072 ppm) or poor signal-to-noise ratio (SNR < 15) or simply a bad fit were excluded. We also excluded spectra if the associated LCModel Inhibitors,research,lifescience,medical concentration estimates Inhibitors,research,lifescience,medical of any metabolite were more than 3.5 standard deviations from the corresponding mean. Finally, we applied an objective data-driven quality control that excluded any spectrum with any data point in the analysis window more than 3.5 standard deviations from corresponding point

in the mean spectrum (generated from all included spectra). Though arbitrary, such a choice http://www.selleckchem.com/products/AZD8055.html allowed us to exclude very few poor quality spectra and realize an in vivo data set with no variance Isotretinoin outliers (N = 193). ICA analysis ICA was performed over the same analysis window used in the LCModel analysis (1.8–4.2 ppm), using the real part of the spectra. Such an approach is suitable for the linear unmixing problem in ICA and also suits the infomax algorithm, which works well with real valued data. Without any further preprocessing, the spectra were mean centered (demeaned) and factorized using singular value decomposition to perform PCA. The number of retained principal components was determined using minimum description length criteria (Rissanen 1983; Ojanen et al.