title: Iterative reconstruction with correction of the spatially variant fan-beam collimator response in neurotransmission SPET imaging.
abstract: The dopamine transporter (DAT) has been shown to be a sensitive indicator of nigrostriatal dopamine function. Although visual inspection is often sufficient to assess DAT imaging, quantification could improve the diagnostic accuracy of single-photon emission tomography (SPET) studies of the dopaminergic system. The aim of this study was to assess the accuracy of quantification of the striatal/background uptake ratio when correction for attenuation, scatter and spatially variant fan-beam collimator response is performed in technetium-99m and iodine-123 SPET imaging. A numerical striatal phantom was implemented, and simulated projections of low-energy photons were obtained by using the SimSET Monte Carlo code. High-energy contamination in 123I studies was modelled from experimental measurements with 99mTc and 123I. The ordered subsets expectation maximisation (OSEM) algorithm was employed in reconstruction. Mean improvements of 8% and 16% were obtained in the calculated striatal/background uptake ratio in the putamen and the caudate, respectively, when the spatially variant point spread function was included in the transition matrix. Ideal scatter correction resulted in improvements in the putamen and caudate of 9% for 99mTc agents and 19% for 123I agents. Improvements averaged 31% in the putamen and 43% in the caudate when correction for attenuation, scatter and spatially variant collimator response was included in the reconstruction.
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Deborah
authors.initials: D
authors.lastname: Pareto
authors.forename: Albert
authors.initials: A
authors.lastname: Cot
authors.forename: Javier
authors.initials: J
authors.lastname: Pavía
authors.forename: Carles
authors.initials: C
authors.lastname: Falcón
authors.forename: Ignacio
authors.initials: I
authors.lastname: Juvells
authors.forename: Francisco
authors.initials: F
authors.lastname: Lomeña
authors.forename: Domènec
authors.initials: D
authors.lastname: Ros
mesh_terms: D000465:Algorithms; D001931:Brain Mapping / Q000379:methods; D003198:Computer Simulation; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D009435:Synaptic Transmission / Q000502:physiology*; D013667:Technetium / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D019275:Radiopharmaceuticals; C493214:SLC6A3 protein, human; D013667:Technetium