*3.3. Voxel-Based Comparisons*

Figure 1 (panels A and B) shows the average *k*icer for ASD and control participants in voxels throughout the brain. In striatal as well as extrastriatal regions, we found no statistically significant differences in the *k*icer values between ASD and controls, and in neither sample did we observe significant associations between the *k*icer values and the AQ total or social interaction subscale scores. These results were similar, regardless of whether we adjusted for confounders, applied varying *k*icer thresholds, used unsmoothed data or data smoothed with a 4 FWHM Gaussian filter, or examined the results for the two PET/CT scanners separately. We did observe, in accordance with the ROI analysis, that *k*icer values in a small cluster of voxels in the left nucleus accumbens, significantly negatively correlated with the AQ attention to detail subscale in the ASD sample (and not in controls) (Figure 1C). At more lenient *p*-value thresholds, this association extended to larger parts of the striatum bilaterally.
