title: Evaluation of Iterative Reconstruction Method and Attenuation Correction in Brain Dopamine Transporter SPECT Using an Anthropomorphic Striatal Phantom.
abstract: OBJECTIVE
  The aim of this study was to determine the optimal reconstruction parameters for iterative reconstruction in different devices and collimators for dopamine transporter (DaT) single-photon emission computed tomography (SPECT). The results were compared between filtered back projection (FBP) and different attenuation correction (AC) methods.
  
  
  METHODS
  An anthropomorphic striatal phantom was filled with (123)I solutions at different striatum-to-background radioactivity ratios. Data were acquired using two SPECT/CT devices, equipped with a low-to-medium-energy general-purpose collimator (cameras A-1 and B-1) and a low-energy high-resolution (LEHR) collimator (cameras A-2 and B-2). The SPECT images were once reconstructed by FBP using Chang's AC and once by ordered subset expectation maximization (OSEM) using both CTAC and Chang's AC; moreover, scatter correction was performed. OSEM on cameras A-1 and A-2 included resolution recovery (RR). The images were analyzed, using the specific binding ratio (SBR). Regions of interest for the background were placed on both frontal and occipital regions.
  
  
  RESULTS
  The optimal number of iterations and subsets was 10i10s on camera A-1, 10i5s on camera A-2, and 7i6s on cameras B-1 and B-2. The optimal full width at half maximum of the Gaussian filter was 2.5 times the pixel size. In the comparison between FBP and OSEM, the quality was superior on OSEM-reconstructed images, although edge artifacts were observed in cameras A-1 and A-2. The SBR recovery of OSEM was higher than that of FBP on cameras A-1 and A-2, while no significant difference was detected on cameras B-1 and B-2. Good linearity of SBR was observed in all cameras. In the comparison between Chang's AC and CTAC, a significant correlation was observed on all cameras. The difference in the background region influenced SBR differently in Chang's AC and CTAC on cameras A-1 and B-1.
  
  
  CONCLUSIONS
  Iterative reconstruction improved image quality on all cameras, although edge artifacts were observed in images captured by cameras with RR. The SBR of OSEM with RR was higher than that of FBP, while the SBR of OSEM without RR was equal to that of FBP. Also, the SBR of Chang's AC varied with different background regions in cameras A-1 and B-1.
authors.affiliation: Division of Medical Quantum Sciences, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Maebatake
authors.affiliation: Radiological Science Course, Department of Health Sciences, School of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Imamura
authors.affiliation: Radiological Science Course, Department of Health Sciences, School of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Kodera
authors.affiliation: Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yamashita
authors.affiliation: Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Himuro
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Baba
authors.affiliation: Division of Medical Quantum Sciences, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Miwa
authors.affiliation: Division of Medical Quantum Sciences, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
keywords: Attenuation correction; Iterative reconstruction; SPECT/CT