The value of intratumoral heterogeneity of 18F-FDG uptake to differentiate between primary benign and malignant musculoskeletal tumours on PET/CT

Objective:

The cumulative standardized uptake value (SUV)–volume histogram (CSH) was reported to be a novel way to characterize heterogeneity in intratumoral tracer uptake. This study investigated the value of fluorine-18 fludeoxyglucose (¹⁸F-FDG) intratumoral heterogeneity in comparison with SUV to discriminate between primary benign and malignant musculoskeletal (MS) tumours.

Methods:

The subjects comprised 85 pathologically proven MS tumours. The area under the curve of CSH (AUC-CSH) was used as a heterogeneity index, with lower values corresponding with increased heterogeneity. As 22 tumours were indiscernible on ¹⁸F-FDG positron emission tomography, maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean) and AUC-CSH were obtained in 63 positive tumours. The Mann–Whitney U test and receiver operating characteristic (ROC) analysis were used for analyses.

Results:

The difference between benign (n = 35) and malignant tumours (n = 28) was significant in AUC-CSH (p = 0.004), but not in SUV_max (p = 0.168) and SUV_mean (p = 0.879). The sensitivity, specificity and accuracy for diagnosing malignancy were 61%, 66% and 64% for SUV_max (optical threshold value, >6.9), 54%, 60% and 57% for SUV_mean (optical threshold value, >3) and 61%, 86% and 75% for AUC-CSH (optical threshold value, ≤0.42), respectively. The area under the ROC curve was significantly higher in AUC-CSH (0.71) than SUV_max (0.60) (p = 0.018) and SUV_mean (0.51) (p = 0.005).

Conclusion:

The heterogeneity index, AUC-CSH, has a higher diagnostic accuracy than SUV analysis in differentiating between primary benign and malignant MS tumours, although it is not sufficiently high enough to obviate histological analysis.

Advances in knowledge:

AUC-CSH can assess the heterogeneity of ¹⁸F-FDG uptake in primary benign and malignant MS tumours, with significantly greater heterogeneity associated with malignant MS tumours. AUC-CSH is more diagnostically accurate than SUV analysis in differentiating between benign and malignant MS tumours.