Quantitative 3.0T MR Spectroscopy Reveals Decreased Creatine Concentration in the Dorsolateral Prefrontal Cortex of Patients with Social Anxiety Disorder

BACKGROUND The brain biochemical changes of social anxiety have not been clarified although there have been a limited number of MR spectroscopic studies which utilized metabolite/creatine ratios. Present study aimed to explore the alteration of absolute metabolite concentration in social anxiety disorder using quantitative MR spectroscopy. MATERIALS AND METHODS With a 3.0T MR scanner, single voxel MR spectroscopy (stimulated echo acquisition mode, TR/TE/TM = 2000/20/16 ms) was performed in the left dorsolateral prefrontal cortex and related regions of nine medication-free patients with social anxiety disorder and nine controls. Absolute metabolite concentration was calculated using tissue water as the internal reference and corrected for the partial volume of cerebrospinal fluid. RESULTS In the left dorsolateral prefrontal cortex, the N-acetyl aspartate/creatine ratio of patients was significantly higher than that of controls, and this was due to the decrease of creatine concentration instead of the increase of N-acetyl aspartate concentration. Furthermore, the creatine concentration of the left dorsolateral prefrontal cortex was negatively correlated with the scores of Liebowitz social anxiety scale. CONCLUSIONS The alteration of creatine level in the left dorsolateral prefrontal cortex suggests abnormal energy metabolism and correlates with symptom severity in social anxiety disorder. And metabolite concentration is preferable to metabolite/creatine ratio for the investigation of individual, absolute metabolite changes in this region of social anxiety disorder.