Research ArticleImaging

The Influence of Minimal Misalignment on the Repeatability of PET Images Examined by the Repositioning of Point Sources

Akira Maebatake, Keishin Morita, Go Akamatsu, Yuji Tsutsui, Kazuhiko Himuro, Shingo Baba and Masayuki Sasaki
Journal of Nuclear Medicine Technology March 2019, 47 (1) 55-59; DOI: https://doi.org/10.2967/jnmt.118.208835

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Setting of point sources. Seven point sources were placed on x-axis (interval, 5 cm). For fixed-position images, data were acquired for 10 min, 5 times serially. For variable-position images, data were acquired for 10 min each with point sources at 0, ±0.5, and ±1.0 mm in x-axis direction to simulate minimum of repositioning.

  • FIGURE 2.
    FIGURE 2.

    Images of point sources at fixed position reconstructed by OSEM and OSEM+PSF with 5 different matrix sizes. Images of point sources far from center became faint and broad. Hot spots were smaller and denser on OSEM+PSF images than on OSEM images.

  • FIGURE 3.
    FIGURE 3.

    Images of point sources at variable positions reconstructed by OSEM and OSEM+PSF with 400 × 400 matrix. Density and shape of point sources differed among positions.

  • FIGURE 4.
    FIGURE 4.

    rMax,i at both fixed and variable positions on OSEM and OSEM+PSF images. At both positions, rMax,i decreased at positions far from center. rMax,i was higher on OSEM+PSF images than on OSEM images.

  • FIGURE 5.
    FIGURE 5.

    FWHM,i at both fixed and variable positions on OSEM and OSEM+PSF images. FWHM,i increased at positions far from center on OSEM images. FWHM,i of OSEM+PSF images was stable at all positions.

Tables

  • TABLE 1

    CVmax,i on OSEM Images

    Position (cm)
    Matrix051015202530
    128 × 128
     Fixed0.39%0.31%0.31%0.56%1.30%1.03%0.52%
     Variable7.06%0.70%3.68%4.90%12.5%11.1%5.40%
    200 × 200
     Fixed0.39%0.49%0.31%0.49%0.32%1.04%1.02%
     Variable7.06%5.84%3.68%0.64%7.80%5.61%1.86%
    256 × 256
     Fixed0.69%0.67%0.46%0.75%0.41%0.88%1.73%
     Variable10.9%3.91%7.68%6.35%5.48%1.14%3.17%
    400 × 400
     Fixed0.49%0.67%0.46%0.98%0.87%0.84%1.18%
     Variable9.13%3.91%5.96%2.58%2.38%1.60%3.29%
    512 × 512
     Fixed0.28%0.67%0.46%0.85%0.80%0.31%0.68%
     Variable4.81%3.91%6.31%1.71%2.07%0.75%2.46%
  • TABLE 2

    CVmax,i on OSEM+PSF Images

    Position (cm)
    Matrix051015202530
    128 × 128
     Fixed0.44%0.84%0.56%0.47%0.33%1.22%1.39%
     Variable9.89%0.92%10.4%7.09%6.83%18.7%5.76%
    200 × 200
     Fixed0.46%0.85%0.50%0.57%0.30%1.09%1.32%
     Variable9.89%10.21%10.4%7.09%6.64%18.7%10.89%
    256 × 256
     Fixed1.55%0.73%0.84%1.00%1.04%1.99%0.92%
     Variable25.1%5.47%31.7%6.97%5.66%8.85%22.1%
    400 × 400
     Fixed1.27%0.73%0.49%1.48%0.69%2.76%1.39%
     Variable18.8%5.47%16.3%16.6%21.0%14.8%13.9%
    512 × 512
     Fixed0.39%0.73%0.41%1.48%1.04%0.88%1.03%
     Variable12.4%5.47%13.7%12.3%10.3%5.33%12.6%
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