title: [Radial long-axis tomography: a new reconstructing algorithm for thallium-201 myocardial SPECT].
abstract: The long-axis (L-A) tomograms of the heart in thallium-201 SPECT have been conventionally reconstructed as those parallel to the midventricular vertical or horizontal L-A plane. We developed a new algorithm for reconstructing the rotated L-A tomograms around the L-A to longitudinally observe thallium-201 myocardial distribution and to provide an optimal view of the cardiac apex. After determining the orientation of the L-A and reconstructing the short-axis (S-A) tomograms using standard techniques, the coordinates of the S-A planes were transformed to the polar coordinates whose origin is located at the position of the L-A in each plane. Then, "radial L-A tomograms", i.e. midventricular L-A planes oriented at the angle of every 6 degrees to the midventricular horizontal L-A plane, were reconstructed. Also, we developed a new technique for analyzing thallium-201 distribution of the L-A tomograms. For the basal 2/3 regions, two profiles which consist of the pixels with maximum count on the upper and lower myocardial portions of the lines (spaced at 1 pitch) vertically to the L-A were computed. For the remaining apical 1/3 regions, the semi-circumferential maximum-count profile from the values of 30 radii spaced at 6 degrees interval were computed. Based on these profiles, a 2D polar representation was then generated. From the study using a cardiac phantom with an apical small infarction, the usefulness of this new tomographic method for the detection of apical myocardial ischemia was demonstrated. The application to the exercise/redistribution studies in patients with effort angina indicated that radial long-axis tomography provides precise information about the longitudinal extent of perfusion defects, particularly in the apical regions.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.forename: A
authors.initials: A
authors.lastname: Tani
authors.forename: R
authors.initials: R
authors.lastname: Morozumi
authors.forename: N
authors.initials: N
authors.lastname: Matsubara
authors.forename: M
authors.initials: M
authors.lastname: Hori
authors.forename: A
authors.initials: A
authors.lastname: Kitabatake
authors.forename: T
authors.initials: T
authors.lastname: Kamada
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Kozuka
authors.forename: K
authors.initials: K
authors.lastname: Kimura
mesh_terms: D000465:Algorithms; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008961:Models, Structural; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D013794:Thallium Radioisotopes