Imagenología
¹H Magnetic Resonance Spectroscopy demonstrates different metabolic features in Gliomatosis Cerebri
Materials and methods
One patient with suspected GC was studied after his informed consent was obtained. MR imaging and MRS were performed with a 1.5-T unit (Avanto®, Siemens Medical Systems, Erlangen, Germany). A localizing Sagittal T1-weighted image was obtained, followed by Axial and Coronal T1-weighted. Axial T2-weighted as well as DARK FLUID or FLAIR images were also acquired. The hybrid Multivoxel 2D Chemical Shift Imaging (CSI) technique uses a Point-Resolved Spectroscopy (PRESS) Double Spin Echo scheme for pre-selection of a Volume of Interest (VOI) that is usually defined to include the abnormality as well as normal appearing brain tissue. We use CHESS for water suppression. In order to avoid a contribution to the spectra from fat signals, the VOI was completely enclosed within the brain and positioned at the center of the phase-encoded Field of View (FOV). VOI consists of an 80 mm x 80 mm region placed within a 160 mm x 160 mm FOV on a 10 mm to 20 mm slice. A 16 x 16 phase-encoding matrix gives an 8 x 8 array of spectra in the VOI with a plane resolution of 10 mm x 10 mm. The parameters used were 1500/30/6 (TR/TE/Acquisitions). Other settings included were a Hamming filter, number of sampling points NP = 1024, BW = 1kHz, preparatory scans = 6, delta frequency = -2.7 ppm. Data underwent apodization through a 1.0 Hz Lorentzian filter, Fourier transformation in time and space, and phase correction. Lipids (Lip), Lactate (Lac), N-Acetylaspartate (NAA), Creatine (Cr), Choline (Cho) and myo-Inositol (mI) intensity signals were detected. NAA/Cr, Cho/Cr, mI/Cr and Cho/NAA ratios were calculated. The GC diagnosis was confirmed by a stereotactic biopsy at the area where Cho/Cr ratio reached the highest value which is represented as an intense red area within the metabolic map showed in Figure 1. |