Statistical mapping analysis of serotonin synthesis images generated in healthy volunteers using positron-emission tomography and alpha-[11C]methyl-L-tryptophan.
OBJECTIVE
To assess the suitability of analyzing functional images of brain serotonin (5-HT) synthesis with statistical parametric mapping (SPM), and to investigate further possible sex-related regional differences.


METHODS
Prospective study.


METHODS
Six healthy men and 5 healthy women.


METHODS
Participants' brains were scanned with positron-emission tomography (PET) after intravenous injection of alpha-[11C]methyl-L-tryptophan (alpha-[11C]MTrp).


METHODS
Tissue radioactivity images were converted into functional images using the Patlak plot approach, and analyzed with 2 methods for global normalization in the SPM program: proportional scaling and analysis of covariance (ANCOVA).


RESULTS
The data structure suggests that PET alpha-[11C]MTrp data meet the criteria for analysis with SPM, and that the proportional scaling method is more appropriate than the ANCOVA method for normalization. Regional differences in 5-HT synthesis were identified between men and women, and the significance of these findings was supported by region of interest (ROI) analyses.


CONCLUSIONS
SPM analyses of PET alpha-[11C]MTrp data may be of value for identifying regional differences in brain 5-HT synthesis between groups, and in investigating the effects of psychotropic drugs. Since we found regional differences between male and female subjects, men and women should not be grouped for data analysis in PET alpha-[11C]MTrp studies.
Okazawa
H
H
Department of Neurology and Neurosurgery, McGill University, Montreal.
Leyton
M
M
Benkelfat
C
C
Mzengeza
S
S
Diksic
M
M
D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011446:Prospective Studies; D012701:Serotonin / Q000096:biosynthesis*; D013223:Statistics as Topic; D014055:Tomography, Emission-Computed; D014364:Tryptophan / Q000031:analogs & derivatives*
D012701:Serotonin; D014364:Tryptophan