Quantification of 5-HT _1a receptors in temporal lobe epilepsy with PET and [ ¹⁸ F]FCWAY: Effect of modeling methods on group discrimination

Previous PET studies with [¹⁸F]FCWAY were modeled with a 120-min kinetic analysis, using arterial input function with corrections for uptake of the metabolite [¹⁸F]fluorocyclohexanecarboxylic acid ([¹⁸F]FC) and vascular activity. We evaluated whether logistically less demanding analysis approaches can be used as alternatives to the full analysis. Dynamic frames were acquired for 120-min in 13 temporal lobe epilepsy (TLE) patients and 10 controls, and modeled with a simplified 3-parameter 2-tissue compartment. The gold standard binding index was <i>BP</i>_F. Images were also generated with a 90-min (<i>BP</i>_{F_90}) and 60-min (<i>BP</i>_{F_60}) data analysis interval, without correction for [¹⁸F]FC (<i>BP</i>_{F_NOFC}) and without neither [¹⁸F]FC correction nor vascular correction (<i>BP</i>_{ND_NOFCVA}). <i>f_P</i> was significantly higher in patients than in controls. <i>BP</i>_{F_NOFC} had very similar statistical power as <i>BP</i>_F, except in the raphe where the effect size of <i>BP</i>_{F_NOFC} was about 40% lower than that of <i>BP</i>_F. <i>BP</i>_{ND_NOFCVA} had poorest performance. Negligible loss of statistical significance in detected differences occurred in the cortex with both <i>BP</i>_{F_90} and <i>BP</i>_{F_60}, but <i>BP</i>_{F_60} was associated with some time instability in the raphe. PET scans can be reduced to 90-min in future, arterial line-based, TLE studies. Lack of correction for [¹⁸F]FC mildly reduced the statistical power only in the raphe.