Individually differentiated serotonergic raphe nuclei measured with brain PET/MR imaging

Area of Science:

• Neuroscience
• Medical Imaging
• Radiochemistry

Background:

• The raphe nuclei are crucial for serotonin production, impacting mood and cognition.
• Accurate measurement of individual raphe nuclei activity is vital for understanding neurological disorders.
• Positron emission tomography (PET) and magnetic resonance (MR) imaging offer complementary insights into brain structure and function.

Purpose of the Study:

• To quantify the metabolic activity and serotonin transporter binding of individual human raphe nuclei.
• To evaluate the utility of fluorine-18 fluorodeoxyglucose (FDG) and carbon-11 (11C) 3-amino-4-(2-dimethylaminomethylphenylthio) benzonitrile (DASB) PET imaging for raphe nuclei assessment.
• To investigate the correlation between glucose metabolism and serotonin transporter availability in the raphe nuclei using a PET/MR imaging system.

Main Methods:

• Seven healthy volunteers underwent simultaneous FDG PET, (11)C-DASB PET, and T2*-weighted MR imaging on a brain PET/MR system.
• Standardized uptake value ratios (SUVR) for FDG and nondisplaceable binding potential (BPnd) for (11)C-DASB were calculated for each raphe nucleus.
• Pearson correlation analysis was employed to determine the relationship between FDG-SUVR and DASB-BPnd.

Main Results:

• Individual raphe nuclei were successfully identified using both FDG and (11)C-DASB PET imaging.
• Mean (11)C-DASB binding potential (BPnd) and FDG uptake (SUVR) varied across the different raphe nuclei.
• A significant positive correlation was observed between FDG-SUVR and DASB-BPnd for the raphe nuclei (r = 0.506, P = .002).

Conclusions:

• Brain PET/MR imaging enables the simultaneous measurement of glucose metabolism and serotonin transporter binding in individual raphe nuclei.
• The findings demonstrate a significant correlation between metabolic activity and serotonergic transporter availability in the raphe nuclei.
• This integrated imaging approach provides a valuable tool for studying serotonergic systems in health and disease.