Research ArticleOriginal Article

Value of metabolic parameters in distinguishing primary mediastinal lymphomas from thymic epithelial tumors

Lei Zhu, Xiaofeng Li, Jian Wang, Qiang Fu, Jianjing Liu, Wenchao Ma, Wengui Xu and Wei Chen
Cancer Biology & Medicine May 2020, 17 (2) 468-477; DOI: https://doi.org/10.20892/j.issn.2095-3941.2019.0428

Article Figures & Data

Figures

  • Figure 1
    Figure 1

    Axial CT, PET, and fusion images (from left to right columns) of examples of primary mediastinal lymphomas (arrows) and thymic epithelial tumors (arrows). Panel A: 43-year-old female patient with diffuse large B-cell lymphoma (CT value = 4–38 Hu; SUVmax = 23.8 g/mL, MTV = 218.0 cm3, and TLG = 2774.9 g/mL cm3); panel B: 70-year-old male patient with squamous cell carcinoma (CT value = 39 Hu with scattered calcifications; SUVmax = 18.7 g/mL, MTV = 36.28 cm3, and TLG = 428.39 g/mL cm3).

  • Figure 2
    Figure 2

    Histograms of age distribution of the patients in this study, showing that most patients with primary mediastinal lymphomas (left panel) were < 40 years of age (76.1%), whereas most patients with thymic epithelial tumors (right panel) were > 40 years of age (87.7%).

  • Figure 3
    Figure 3

    The mean metabolic tumor volume (A) and total lesion glycolysis (B) in the patients with primary mediastinal lymphomas and thymic epithelial tumors, and a separate comparison for each subgroup of primary mediastinal lymphoma (C) and thymic epithelial tumors (D).

  • Figure 4
    Figure 4

    ROC curve and area under the curve of the maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) in differentiating patients with malignant tumors from patients with benign tumors in the pre-vascular compartment of the mediastinum.

  • Figure 5
    Figure 5

    ROC curve and area under the curve of the maximum standard uptake value and mean standard uptake value in differentiating patients with thymic epithelial tumors from patients with primary mediastinal lymphomas in the pre-vascular compartment of the mediastinum (A). The areas under the curve were significantly greater when age was involved as an index (B) in differentiating patients with thymic epithelial tumors from patients with primary mediastinal lymphomas.

Tables

  • Table 1

    Demographics of patients diagnosed with primary mediastinal lymphoma and thymic epithelial tumors in this study

    Pathological subtypesNAgeAge rangeMale (%)
    Primary mediastinal lymphoma71 (52.2%)30.25 ± 14.443–7022 (31.0)
     Classic Hodgkin lymphoma2626.19 ± 9.826–5023.1
     Diffuse large B-cell lymphoma3036.43 ± 14.115–7030.0
     T-lymphoblastic lymphoma919.33 ± 16.93–4655.6
     Other types633.33 ± 16.8613–5933.3
    Thymic epithelial tumors65 (47.8%)54.23 ± 15.1612–7740 (61.5)
     Thymoma_A464.75 ± 7.4155–7350.0
     Thymoma_AB457.00 ± 9.1346–6850.0
     Thymoma_B1853.88 ± 12.5141–7662.5
     Thymoma_B2652.5 ± 21.6716–7266.7
     Thymoma_B3448.75 ± 13.333–6475.0
     Thymic carcinomas3953.77 ± 15.9712–7761.5
      Squamous cell carcinoma2655.19 ± 15.4812–7661.5
      Neuroendocrine carcinoma858.25 ± 17.4326–7762.5
      Adenocarcinoma/sarcoma539.2 ± 8.5824–4560.0
    Total13641.57 ± 19.123–7762 (45.6)
  • Table 2

    Group comparison between the primary mediastinal lymphoma and thymic epithelial tumors

    Primary mediastinal lymphomaThymic epithelial tumorsGroup comparison
    χ2P
    Age55.19< 0.001**
     < 40548
     ≥ 401757
    Sex12.68< 0.001**
     Male2240
     Female4925
    Malignancy33.21< 0.001**
     Malignant7140
     Benign025
    SUVmax16.55 ± 6.3810.64 ± 6.1628.18< 0.001**
     < 13.7274817.47< 0.001**
     ≥ 13.74417
    SUVmean9.80 ± 3.936.11 ± 3.5528.93< 0.001**
     < 8.0294916.43< 0.001**
     ≥ 8.04216
    MTV (cm3)143.98 ± 149.9384.99 ± 130.105.74< 0.05*
     < 115.8395310.9= 0.001**
     ≥ 115.83212
    TLG (g/mL cm3)1546.1 ± 1838.69641.78 ± 1381.4514.55< 0.001**
     < 1113.9425713.85< 0.001**
     ≥ 1113.9298

    SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; MTV, metabolic tumor volume; TLG, total lesion glycolysis; * and ** represent significant differences of P < 0.05 and P < 0.01, respectively.

    • Table 3

      Comparisons of metabolic and volumetric parameters in groups of patients with primary mediastinal lymphoma and thymic epithelial tumors

      Pathological subtypesSUVmaxSUVmeanMTVTLG
      Total13.72 ± 6.928.03 ± 4.17115.79 ± 143.371113.95 ± 1692.13
      Primary mediastinal lymphoma16.55 ± 6.389.80 ± 3.93143.98 ± 149.931546.15 ± 1838.69
       Classic Hodgkin lymphoma14.05 ± 5.278.51 ± 3.5373.4 ± 101.75669.34 ± 888.29
       Diffuse large B-cell lymphoma20.81 ± 5.6912.28 ± 3.44180.92 ± 143.322327.82 ± 2082.62
       T-lymphoblastic lymphoma11.94 ± 3.396.87 ± 1.95188.06 ± 134.801459.41 ± 1387.87
       Other types12.99 ± 5.537.32 ± 3.25199.05 ± 271.131567.05 ± 2733.1
        χ2, P23.34, < 0.00122.47, < 0.00113.15, 0.00413.96, 0.003
      Thymic epithelial tumors10.64 ± 6.166.11 ± 3.5584.99 ± 130.10641.78 ± 1381.45
       Thymoma_A6.37 ± 0.863.76 ± 0.5215.65 ± 7.7756.34 ± 24.43
       Thymoma_AB5.37 ± 2.003.14 ± 1.2852.94 ± 36.31136.72 ± 53.78
       Thymoma_B16.16 ± 2.613.59 ± 1.7139.21 ± 22.59122.32 ± 58.77
       Thymoma_B28.65 ± 3.855.07 ± 2.3043.29 ± 21.51210.08 ± 137.81
       Thymoma_B39.91 ± 8.485.97 ± 5.3759.60 ± 38.04317.35 ± 253.83
       Thymic carcinomas12.91 ± 6.297.35 ± 3.60113.79 ± 160.87959.87 ± 1715.11
        Squamous cell carcinoma14.22 ± 6.688.25 ± 3.8699.86 ± 121.291005.18 ± 1872.20
        Neuroendocrine carcinoma9.99 ± 3.945.86 ± 2.34184.24 ± 278.801168.21 ± 1754.16
        Adenocarcinoma/sarcoma10.78 ± 5.985.04 ± 2.0673.54 ± 68.25391.46 ± 386.17
        χ2, P22.51, 0.00223.05, 0.00211.58, > 0.0520.61, 0.004

      SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; MTV, metabolic tumor volume; TLG, total lesion glycolysis.

      • Table 4

        Diagnostic ability of metabolic and volumetric parameters of PET/CT in differentiating patients with primary mediastinal lymphoma versus thymic epithelial tumors

        Cut-off valuesSensitivity (%)Specificity (%)Accuracy (%)AUC (95% CI)
        SUVmax12.370.470.870.60.764 (0.685–0.843)
        SUVmean6.976.169.372.80.767 (0.688–0.847)
        TLG (g/mL cm3)350.370.463.169.00.690 (0.599–0.780)
        MTV (cm3)10646.581.566.10.619 (0.524–0.715)
        SUVmax + TLG/66.273.2/0.768 (0.689–0.847)
        SUVmax + age/80.093.0/0.908 (0.855–0.961)
        SUVmean + age/83.188.7/0.912 (0.861–0.964)

        SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; MTV, metabolic tumor volume; TLG, total lesion glycolysis.

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