Original article

Annals of Nuclear Medicine

, Volume 26, Issue 3, pp 222-227

Intratumoral heterogeneity of F-18 FDG uptake differentiates between gastrointestinal stromal tumors and abdominal malignant lymphomas on PET/CT

  • Tadashi WatabeAffiliated withDepartment of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University HospitalImmunology Frontier Research Center, Osaka University
  • , Mitsuaki TatsumiAffiliated withDepartment of Nuclear Medicine, Osaka University HospitalDepartment of Radiology, Osaka University Hospital
  • , Hiroshi WatabeAffiliated withDepartment of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine
  • , Kayako IsohashiAffiliated withDepartment of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University Hospital
  • , Hiroki KatoAffiliated withDepartment of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University Hospital
  • , Masahiro YanagawaAffiliated withDepartment of Radiology, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University Hospital
  • , Eku ShimosegawaAffiliated withDepartment of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University Hospital
  • , Jun HatazawaAffiliated withDepartment of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of MedicineDepartment of Nuclear Medicine, Osaka University HospitalImmunology Frontier Research Center, Osaka University Email author 

Abstract

Objective

Gastrointestinal stromal tumors (GISTs) and malignant lymphomas (MLs) in the abdomen are often observed as tumors of unknown origin on F-18 FDG PET/CT. The purpose of this study was to evaluate the intratumoral metabolic heterogeneity of F-18 FDG uptake on PET to determine if it might be helpful to discriminate between these tumors.

Methods

The F-18 FDG PET/CT findings of 21 large abdominal tumors were retrospectively evaluated (9 GISTs and 12 MLs). Intratumoral heterogeneity was evaluated by visual scoring (visual score: 0, homogeneous; 1, slightly heterogeneous; 2, moderately heterogeneous; 3, highly heterogeneous) and by the cumulative standardized uptake value (SUV) histograms on transaxial PET images at the maximal cross-sectional tumor diameter. Percent tumor areas above a threshold from 0 to 100% of the maximum SUV were plotted and the area under curve of the cumulative SUV histograms (AUC-CSH) was used as a heterogeneity index, where lower values corresponded with increased heterogeneity. Correlation between the visual score and the AUC-CSH was investigated by the Spearman’s rank test.

Results

GISTs exhibited heterogeneous uptake of F-18 FDG, whereas MLs showed rather homogeneous uptake on visual analysis (visual score: 2.67 ± 0.50 and 0.58 ± 0.79, respectively; p < 0.001). The AUC-CSH was significantly lower for the GISTs than for the MLs (0.41 ± 0.14 and 0.64 ± 0.08, respectively; p < 0.001). Significant correlations were observed between the visual score and the AUC-CSH (ρ = −0.866, p < 0.001).

Conclusion

GISTs exhibited significantly heterogeneous intratumoral tracer uptake as compared with the MLs. Evaluation of the intratumoral heterogeneity of F-18 FDG uptake may help in the discrimination between these tumors.

Keywords

F-18 FDG PET Intratumoral heterogeneity Gastrointestinal stromal tumor Malignant lymphoma Cumulative standardized uptake value histograms