Figure 2.

Visualization and quantitation of [¹⁸F]FTC-146 accumulation in rats with and without nerve injury via PET/MRI and ex vivo autoradiography. (A) Diagram of a rat depicting the location of the PET/MR image slices. A labeled version of the MR and PET/MR fused image slice is shown, whereby 1 = knee joint, 2 = penile urethra, 3 = site of nerve injury (i.e., neuroma), 4 = fiducial, and 5 = vein and tail. (B) Representative axial PET/MR images through the thighs of SNI, SNI (pre-blocked), sham, and control rats. The White arrow points to [¹⁸F]FTC-146 accumulation in the injured left nerve of SNI rat. (C) Ex vivo autoradiography of representative excised whole sciatic nerves from SNI, SNI (pre-blocked), sham, and control rats. Nerve 1 is the right (uninjured) whereas nerve 2 is the left (injured) sciatic nerve from a representative SNI rat; nerves 3 and 4 are the right (uninjured) and left (injured) sciatic nerves from a SNI rat - however this rat was pre-treated with a haloperidol prior to radiotracer administration, thus serving to block accumulation of [¹⁸F]FTC-146; nerves 5 and 6 are the right and left sciatic nerves from a sham-operated rat (sham surgery was performed on left side of the rat without causing nerve injury); nerves 7 and 8 are the right and left sciatic nerves from a control rat. White arrow points to the neuroma of the left injured nerve of a SNI rat. (D) Pain assessment of rat groups for PET/MRI and autoradiography images by von Frey tests. (E) The average normalized maximum signal in left and right sciatic nerves from rats in each group as determined via PET/MRI (n = 4). (F) Signal intensity in left and right sciatic nerves from rats in each group as determined via ex vivo autoradiography of whole nerves (n = 2). Error bars represent standard error of the mean value. ****p<0.0005, ***p<0.005.