Serotonin transporter availability in thalamic subregions in schizophrenia: A study using 7.0-T MRI with [11C]DASB high-resolution PET

• The SERT availability was examined in thalamic subdivisions with high-resolution PET–MRI.
• No significant differences were found in SERT availability between schizophrenia and control groups.
• Negative symptom severity showed a negative correlation with SERT availability in the left anterior thalamic nucleus.
• The high-resolution imaging system combining structural and molecular information is an important asset for in vivo clinical research.

The serotonin transporter (SERT) is an integral protein that provides an index of serotonergic innervation. Until recently, few studies have investigated SERT binding in thalamic subregions in schizophrenia. The purpose of this study was to examine SERT availability in thalamic subdivisions (anterior nucleus, mediodorsal nucleus, and pulvinar) using 7.0-T magnetic resonance imaging (MRI) and high-resolution positron emission tomography (PET) with 11C-3-amino-4-(2-dimethylaminomethylphenylthio)benzonitrile ([11C]DASB) in schizophrenia. Antipsychotic-free patients with schizophrenia (n=12) and healthy controls (n=15) underwent PET and MRI scans. For SERT availability, the binding potential with respect to non-displaceable compartment (BPND) was derived using the simplified reference tissue model (SRTM2). The analysis revealed that there were no significant differences in SERT availability between the two groups. In patients with schizophrenia, the severity of negative symptoms had a negative correlation with SERT availability in the anterior nucleus of the left thalamus. The present study did not reveal significant differences in SERT availability in thalamic subdivisions between patients with schizophrenia and control subjects. The association of SERT availability in the anterior nucleus with negative symptoms may suggest a role for the anterior thalamic nucleus in the pathophysiology of symptoms of schizophrenia. The ultra-high resolution imaging system could be an important asset for in vivo psychiatric research by combining structural and molecular information.