Research ArticleImaging

Optimization of Number of Iterations as a Reconstruction Parameter in Bone SPECT Imaging Using a Novel Thoracic Spine Phantom

Mitsuha Fukami, Norikazu Matsutomo and Tomoaki Yamamoto
Journal of Nuclear Medicine Technology June 2021, 49 (2) 143-149; DOI: https://doi.org/10.2967/jnmt.120.253534

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    (A) Axial diagram of ISMM phantom. (B) Coronal diagram of ISMM phantom. (C) Photograph of thoracic spine ISMM phantom; vertebra and tumors are shown on left, and torso and lungs are shown on right.

  • FIGURE 2.
    FIGURE 2.

    Axial (A) and coronal (B) diagrams of VOIs. VOIs 1, 2, and 3 were defined as background, tumor (28 mm), and vertebra, respectively. VOIs of other tumor sizes were defined similarly to 28-mm tumor.

  • FIGURE 3.
    FIGURE 3.

    Comparison of FWHM (A), %CV (B), and contrast (C) according to number of iterations. Number of subsets was fixed at 10, and number of iterations was varied from 1 to 40. FWHM decreased as number of iterations was increased, and FWHM converged uniformly when number of iterations exceeded 10. %CV increased as number of iterations was increased. Contrast increased as number of iterations was increased, and contrast converged uniformly when number of iterations exceeded 5.

  • FIGURE 4.
    FIGURE 4.

    Comparison of RC by size of sphere. Number of subsets was fixed at 10, and number of iterations was varied from 1 to 40. RC decreased with decreasing sphere size.

  • FIGURE 5.
    FIGURE 5.

    Comparison of SUVmax (A), SUVpeak (B), and SUVmean (C) according to number of iterations. Number of subsets was fixed at 10, and number of iterations was varied from 1 to 40. As number of iterations was increased, all SUVs increased and converged uniformly.

  • FIGURE 6.
    FIGURE 6.

    SPECT images of thoracic spine with various numbers of iterations. Number of subsets was fixed at 10, and number of iterations was 1, 2, 3, 5, 10, 20, 25, 30, 35, and 40.

Tables

  • TABLE 1

    Visual Assessment Results Varied According to Numbers of Iterations

    Number of iterationsAverage score
    12.1 ± 0.6
    22.2 ± 0.8
    32.5 ± 0.5
    51.9 ± 0.6
    102.8 ± 0.8
    202.5 ± 0.5
    252.7 ± 0.7
    302.7 ± 0.7
    352.9 ± 0.7
    402.8 ± 0.6
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