Dynamics of γ-aminobutyric acid concentration in the human brain in response to short visual stimulation.

Objective: To find a possible quantitative relation between activation-induced fast (< 10 s) changes in the γ-aminobutyric acid (GABA) level and the amplitude of a blood oxygen level-dependent contrast (BOLD) response (according to magnetic resonance spectroscopy [MRS] and functional magnetic resonance imaging [fMRI]).

Materials And Methods: fMRI data and MEGA-PRESS magnetic resonance spectra [echo time (TE)/repetition time (TR) = 68 ms/1500 ms] of an activated area in the visual cortex of 33 subjects were acquired using a 3 T MR scanner. Stimulation was performed by presenting an image of a flickering checkerboard for 3 s, repeated with an interval of 13.

T Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation.

Background: In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T mapping, a well-established method for cartilage lesions assessment.

Purpose: To examine short-term consequences of single first-time LPD in teenagers by T mapping of the patellar-cartilage state.

Study Type: Prospective.

Macromolecular-Suppressed GABA-Edited MR Spectroscopy in the Posterior Cingulate Cortex of Patients With Acute Mild Traumatic Brain Injury.

Background: Mild traumatic brain injury (mTBI) causes a number of molecular and cellular alterations. There is evidence of an imbalance between the main excitatory (glutamate, Glu) and the main inhibitory (gamma-aminobutyric acid [GABA]) neurotransmitters following mTBI. In vivo human GABA-Glu balance studies following mTBI are sparse.

Separate N-acetyl aspartyl glutamate, N-acetyl aspartate, aspartate, and glutamate quantification after pediatric mild traumatic brain injury in the acute phase.

Purpose: To separately measure N-acetyl aspartul glutamate (NAAG), N-acetyl aspartate (NAA), aspartate (Asp), and glutamate (Glu) concentrations in white matter (WM) using J-editing techniques in patients with mild traumatic brain injury (mTBI) in the acute phase.

Methods: Twenty-four patients with closed concussive head injury and 29 healthy volunteers were enrolled in the current study. For extended H MRS examination, patients and controls were equally divided into two subgroups.

T measurement and quantification of cerebral white and gray matter aspartate concentrations in vivo at 3T: a MEGA-PRESS study.

Purpose: To measure the transverse relaxation rate (T ) of aspartate (Asp) from Asp-edited MEGA-PRESS spectra and use the measured T values to estimate the Asp concentrations in gray matter (GM)- and white matter (WM)-dominant brain regions.

Methods: Since Asp-edited MEGA-PRESS spectra contain non-overlapped Asp signals, TE-dependence arising from J-evolution can be considered using phantom MEGA-PRESS spectra acquired with the same parameters as in vivo spectra. Four TE values (90, 115, 140, and 150 ms) were selected from numeric analyses for effective detection of the edited Asp multiplet at ~2.