Figure 3(a) (Media 1) and 3(b) (Media 2) compare the SV image quality with and without subpixel image registration realignment, clearly showing less bulk tissue signal and higher vascular contrast in the realigned image.
Using the EORTC/SUVmax-based criteria, 5/37 patients had a discordant response of thoracic, and 2/12 a discordant response of non-thoracic lesions between the reference and the realigned image.
Using the mean realigned image, all images were coregistered to a segmented high-resolution structural scan (voxel size, 1 × 1 × 1 mm) using a normalized mutual information cost function.
using standardized procedures (Friston et al., 1994; Friston, 2007), including realignment for head movements using the first scan of each participant as a reference, and spatial warping to a standardized anatomic space (Talairach and Tournoux, 1988), by matching each realigned image to the PET template of the Montreal Neurological Institute (MNI) (Friston et al., 1995).
Equivalence between reference and realigned images was tested (determining 95% range of the difference) and estimating the percentage of voxel values that fell within that range.
The extra-thoracic locations aligned above 90% of the voxels in all patients implicating that movement control was adequate (Table 1). Figure 2 Equivalence plot between reference and realigned images of 39 patients.
The realigned images were spatially normalized to the standard EPI template, resampled to 3×3×3 mm3 and smoothed using an 8-mm full-width-at-half-maximum Gaussian kernel to decrease spatial noise.
As CT and SPECT images are generated sequentially we realigned images using a three dimensional external fiducial containing 1 MBq of 99m-technetium (99mTc) in a small plastic tubing (Portex, Smith Medical, Ashford, Kent, UK) detectable with CT and firmly fixed to the neck region of the mice.
The realigned images were then normalized to an EPI template in Montreal Neurological Institute (MNI) stereotactic space.
All statistical analyses were performed on these smoothed and realigned images.
The realigned images were coregistered with individual anatomical images, spatially normalized to the MNI152 brain template (Montreal Neurological Institute, Montreal, Canada) and resampled to 2 × 2 × 2 mm.
