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

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 (q = -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.

Visual Versus Quantitative Assessment of Intratumor 18F-FDG PET Uptake Heterogeneity: Prognostic Value in Non–Small Cell Lung Cancer

“…These volumes were also much larger (119 6 102 cm 3 ) than in our study (48 6 58 cm 3 ), suggesting that CH AUC and SUV COV might be appropriate to characterize high heterogeneity levels as found in large GIST and ML lesions but may not be sufficient to quantify finer heterogeneity differences found in smaller NSCLC tumors. This is also supported by the distributions of CH AUC values, with a small range (SD 5 0.05) in our study (0.32 6 0.05), compared with those found in Watabe et al (0.41 6 0.14 for GIST and 0.64 6 0.08 for ML) (31). Finally, FLAB delineation excluded areas with uptake similar to the background or lower, contrary to manual delineation, as in Watabe et al However, only 4 cases presented areas with uptake low enough to be excluded and already presented large volumes and high heterogeneity.…”

The value of intratumoral heterogeneity of18F-FDG uptake to differentiate between primary benign and malignant musculoskeletal tumours on PET/CT

“…1,2 Glucose analogue fluorine-18 fludeoxyglucose ( 18 F-FDG) represents the lesion glycolytic activity and has been widely used as a tracer of positron emission tomography (PET) 3 and PET/CT in oncology. 4 There is increasing evidence in the literature 5,6 to support the incremental benefit of 18 F-FDG PET/CT in the evaluation of MS tumours along with conventional anatomical imaging. 18 F-FDG uptake in a lesion has been evaluated using a visual scoring system and maximum or mean standardized uptake value (SUV) for characterization of MS tumours.…”

“…4 There is increasing evidence in the literature 5,6 to support the incremental benefit of 18 F-FDG PET/CT in the evaluation of MS tumours along with conventional anatomical imaging. 18 F-FDG uptake in a lesion has been evaluated using a visual scoring system and maximum or mean standardized uptake value (SUV) for characterization of MS tumours. However, there is controversy over the degree of 18 F-FDG uptake to differentiate between benign and malignant MS tumours because of a certain amount of overlap in 18 F-FDG uptake between them.…”

“…18 F-FDG uptake in a lesion has been evaluated using a visual scoring system and maximum or mean standardized uptake value (SUV) for characterization of MS tumours. However, there is controversy over the degree of 18 F-FDG uptake to differentiate between benign and malignant MS tumours because of a certain amount of overlap in 18 F-FDG uptake between them. [6][7][8][9] In general, 18 F-FDG uptake in tumours is not homogeneous, and this heterogeneity might be attributed to necrosis, 10 cellular proliferation, 11 blood flow, 12 microvessel density 13 and hypoxia.…”

“…However, there is controversy over the degree of 18 F-FDG uptake to differentiate between benign and malignant MS tumours because of a certain amount of overlap in 18 F-FDG uptake between them. [6][7][8][9] In general, 18 F-FDG uptake in tumours is not homogeneous, and this heterogeneity might be attributed to necrosis, 10 cellular proliferation, 11 blood flow, 12 microvessel density 13 and hypoxia. [14][15][16] Thus, the evaluation of the intratumoral heterogeneity of 18 F-FDG uptake may provide us with the additional information about the tumour characteristics.…”