Diagnostic ability of [18F]FDG PET/CT for distinguishing benign from malignant spleen lesions.

Objectives: [¹⁸F]Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a non-invasive imaging modality used in the differential diagnosis of splenic lesions, although ideal parameters and thresholds remain unclear. The present study evaluated the ability of [¹⁸F]FDG PET/CT, including its visual and quantitative parameters, to differentiate between benign and malignant splenic lesions.

Methods: Patients who underwent [¹⁸F]FDG PET/CT following the detection of splenic lesions on contrast-enhanced CT were retrospectively analysed. Visual parameters assessed on [¹⁸F]FDG PET/CT included whole spleen uptake intensity, lesion multiplicity, and lesion uptake, and quantitative parameters included maximum standardised uptake value (SUVmax), lesion-to-background ratio (LBR), metabolic tumour volume (MTV), total lesion glycolysis (TLG), and lesion size. Parameters differentiating between benign and malignant lesions were evaluated by Pearson's chi-square test, Mann-Whitney U-test, and receiver operating characteristics (ROC) curve analysis.

Results: Splenic lesion uptake (p = 0.001) was the only visual parameter significantly distinguishing between benign and malignant lesions. ROC curve analysis demonstrated that SUVmax had the largest area under the ROC, 0.91 (p < 0.001), with an optimal cut-off > 5.3 having a sensitivity of 90.3% and a specificity of 80.6%. Subgroup analysis of malignant lesions showed that SUVmax (p = 0.013), LBR (p = 0.012), and TLG (p  = 0.034) were significantly higher in splenic lymphomas than in splenic metastases.

Conclusion: Of the [¹⁸F]FDG PET/CT parameters investigated, SUVmax had the highest accuracy in diagnosing malignant splenic lesions and was significantly higher in splenic lymphomas than in splenic metastases. Visual determination of [¹⁸F]FDG uptake by splenic lesions may be an easily evaluated parameter.

Clinical relevance statement: SUVmax and visual grade of [¹⁸F]FDG PET/CT help to differentiate spleen lesions. [¹⁸F]FDG PET/CT is useful for discriminating between benign and malignant spleen lesions.

Key points: Many splenic lesions are difficult to diagnose on anatomical imaging, with histopathologic analyses are required. SUVmax of PET/CT provided the diagnostic ability to differentiate between benign and malignant splenic lesions. More than normal spleen uptake can be a convenient parameter to diagnose malignant spleen lesions.