SPECT data were obtained with a Siemens Symbia T2 series SPECT•CT scanner with low energy high-resolution collimators (full width at half-maximum 7.4mm) and two-slice CT. The ligand, (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2-hydroxy-3-iodo-6-methoxybenzamide ([123I]-IBZM) was chosen due to its selectivity for striatal D2/3 receptors.58 (link),59 (link) All participants received 185mBq [123I]-IBZM per scanning (GE Healthcare). The SPECT scanning was performed using the constant infusion technique.60 (link),61 (link) A CT scout and 2×30min tomography were performed. The individually adjusted dose of amisulpride was administered to all patients at same time, 3h prior to the SPECT scanning at follow-up.
Plasma free fraction of [123I]-IBZM was determined using ultrafiltration (Centrifree, 30000 MW).62 (link) The plasma metabolite analysis of [123I]-IBZM was performed using Oasis WCX (Waters) solid phase extraction units and stepwise elution with water, 40% acetonitrile and acidified 95% methanol. The native compound was eluted in the water phase and the metabolites in the subsequent elution.
All participants had a structural MRI scan performed for co-registration. The HC were only scanned at baseline to reduce the radiation dose.
Note that the supplementary material contains the details of the SPECT and MRI acquisitions.
Plasma free fraction of [123I]-IBZM was determined using ultrafiltration (Centrifree, 30000 MW).62 (link) The plasma metabolite analysis of [123I]-IBZM was performed using Oasis WCX (Waters) solid phase extraction units and stepwise elution with water, 40% acetonitrile and acidified 95% methanol. The native compound was eluted in the water phase and the metabolites in the subsequent elution.
All participants had a structural MRI scan performed for co-registration. The HC were only scanned at baseline to reduce the radiation dose.
Note that the supplementary material contains the details of the SPECT and MRI acquisitions.