title: Radius dependence of FP-CIT quantification: a Monte Carlo-based simulation study.
abstract: OBJECTIVE
  Dopamine transporter imaging with SPECT is a valuable tool for both clinical routine and research studies. Semi-quantitative analysis plays a key role in interpreting the scans, but is dependent on numerous factors, rotational radius being one of them. This study systematically evaluates the potential influence of radius of rotation on apparent tracer binding and describes methods for correction.
  
  
  METHODS
  Monte Carlo simulation scans of a digital brain phantom with various disease states and various radii of rotation ranging from 13 to 30 cm were analyzed using 4 different methods of semi-quantification. Different volumes of interest as well as a method with partial volume correction were applied.
  
  
  RESULTS
  For conventional 3D semi-quantification methods the decrease of measured striatal binding per cm additional radius rotation lied in the range between 2.5 and 3.1 %, whereas effects were negligible when applying recovery-corrected quantification. Effects were independent of disease state.
  
  
  CONCLUSIONS
  Partial volume effects with increasing radius of rotation can lead to considerable decrease of measured binding ratios, particularly when applying dopamine transporter imaging in a research setting. Standardization of acquisition radius can avoid the effect; correction seems feasible, but the correction factors depend on the quantification approach applied.
authors.affiliation: Department of Nuclear Medicine, University of Munich, Marchioninistr. 15, 81377, Munich, Germany, walter.koch@med.uni-muenchen.de.
authors.forename: Walter
authors.initials: W
authors.lastname: Koch
authors.forename: Peter
authors.initials: P
authors.lastname: Bartenstein
authors.forename: Christian
authors.initials: C
authors.lastname: la Fougère
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D001927:Brain Diseases / Q000000981:diagnostic imaging / Q000378:metabolism; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism; D003198:Computer Simulation; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism; D018450:Disease Progression; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D006801:Humans; D008959:Models, Neurological; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism; D019275:Radiopharmaceuticals; D012399:Rotation; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014326:Tropanes
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D019275:Radiopharmaceuticals; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane