title: Simultaneous acquisition of iodine-123 emission and technetium-99m transmission data for quantitative brain single-photon emission tomographic imaging.
abstract: The aim of this study was to obtain quantitative iodine-123 brain single-photon emission tomographic (SPET) images with scatter and attenuation correction. We used a triple-headed SPET gamma camera system equipped with fan-beam collimators with a technetium-99m line transmission source placed at one of the focal lines of the fan-beam collimators. Four energy windows were employed for data acquisition: (a) 126-132 keV, (b) 132-143 keV, (c) 143-175 keV and (d) 175-186 keV. A simultaneous transmission-emission computed tomography scan (TCT-ECT) was carried out for a brain phantom containing 123I solution. The triple energy window scatter correction was applied to the 123I ECT data measured by means of the windows (b), (c) and (d) acquired by two detectors. Attenuation maps were reconstructed from 99mTc TCT data measured by means of the windows (a), (b) and (c) acquired by one detector. Chang's iterative attenuation correction method using the attenuation maps was applied to the 123I ECT images. In the phantom study cross-calibrated SPET values obtained with the simultaneous mode were almost equal to those obtained with the sequential mode, and they were close to the true value, within an error range of 5.5%. In the human study corrected images showed a higher grey-to-white matter count ratio and relatively higher uptake in the cerebellum, basal ganglia and thalamus than uncorrected images. We conclude that this correction method provides improved quantification and quality of SPET images and that the method is clinically practical because it requires only a single scan with a 99mTc external source.
authors.affiliation: Department of Radiology, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ogasawara
authors.forename: J
authors.initials: J
authors.lastname: Hashimoto
authors.forename: K
authors.initials: K
authors.lastname: Ogawa
authors.forename: A
authors.initials: A
authors.lastname: Kubo
authors.forename: N
authors.initials: N
authors.lastname: Motomura
authors.forename: H
authors.initials: H
authors.lastname: Hasegawa
authors.forename: T
authors.initials: T
authors.lastname: Ichihara
mesh_terms: D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D002138:Calibration; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007457:Iodine Radioisotopes; D008953:Models, Anatomic; D017556:Technetium Compounds; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007457:Iodine Radioisotopes; D017556:Technetium Compounds