Research ArticleImaging

Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Patient-Specific Breathing–Instructed CT

Charlotte S. van der Vos, Antoi P.W. Meeuwis, Willem Grootjans, Lioe-Fee de Geus-Oei and Eric P. Visser
Journal of Nuclear Medicine Technology June 2019, 47 (2) 154-159; DOI: https://doi.org/10.2967/jnmt.118.215970

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Example of respiratory signal before and during CT acquisition. Patients were instructed to hold their breath between amplitude limits of optimal PET gate (between horizontal lines). To determine whether patient complied with instructions, amplitude range of respiratory signal before start of CT scan (mean amplitude range over several respiratory cycles) and during breathing instructions was determined. Ratio between those two was used to determine whether patients were able to hold their breath.

  • FIGURE 2.
    FIGURE 2.

    Ratios between average amplitude range of respiratory signal during breathing instructions and before CT acquisition, for each patient. Patients 1, 11, 12, and 20 could not comply with breathing instructions and showed higher ratio than other patients. When amplitude during CT acquisition of only lungs (not including upper abdomen region) was considered, ratios of patients 12 and 20 improved; therefore, they could be included in data analysis. Patients 1 and 11 showed only slight or no improvement and were excluded from data analysis.

  • FIGURE 3.
    FIGURE 3.

    Patient with small cell lung cancer. (A and B) Transaxial (A) and coronal (B) planes of standard CT fused with respiration-gated PET image showed mismatch. (C and D) Same transaxial (C) and coronal (D) plane of CT with breathing instructions and corresponding gated PET images showed improved match. (A color version of this figure is available as a supplemental file at http://tech.snmjournals.org.)

  • FIGURE 4.
    FIGURE 4.

    Scatterplot showing results of distance between centroids for lesions between PET and breath-hold (BH) CT and between PET and standard CT.

Tables

  • TABLE 1

    Patient Characteristics

    CharacteristicData
    Sex (n)
     Male12
     Female8
    Mean age (y)64.2 (SD, 9.2)
    Mean weight (kg)76.3 (SD, 18.1)
    Mean administered activity (MBq)210 (SD, 105)
    Diagnosis (n)
     Primary lung cancer10
     Metastasis6
     Other and unconfirmed4
    Location of lesion (n)
     Upper lobes16
     Middle and lower lobes9
     Lung hilum6
  • TABLE 2

    Results of Analyses of Spatial Alignment for Both Patient Groups

    ParameterStandard CT and PETBreath-hold CT and PETP
    Mismatch of lung–liver boundary (mm)5.6 ± 7.31.7 ± 2.10.049
    Average distance between lesion centroids (mm)5.5 ± 6.53.6 ± 2.00.040
    Jaccard similarity coefficient0.32 ± 0.160.36 ± 0.160.176
    SUVmax (g/cm3)10.3 ± 6.410.6 ± 6.60.104
    SUVmean (g/cm3)6.1 ± 3.86.3 ± 3.90.044
    Metabolic tumor volume6.73 ± 15.66.69 ± 15.70.930
    TLG54.50 ± 143.454.55 ± 141.90.018

    • Data are mean and SD.

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