Purpose: The aim was to explore undefined useful indices for clinically grading adult T-cell leukemia (ATL) using [18F] 2-fluoro-2-deoxyglucose (FDG) - positron emission tomography/computed tomography (PET/CT).
Methods: A total of 28 patients with ATL (indolent, 9; aggressive, 19) were enrolled; all patients with aggressive ATL underwent FDG-PET/CT before chemotherapy. Patients with indolent ATL underwent FDG-PET/CT at the time of suspected disease progression and/or transformation; some received lymph node biopsy. The quantitative parameters maximum standardized uptake values (SUVmax), and mean and peak SUV, metabolic tumor volume (MTV), and volume-based total lesion glycolysis were calculated with the margin threshold as 25%, and 50% of the SUVmax for all lesions.
Results: All parameters except for MTV-25% showed significant differences (P ≤ 0.05) in differentiating the aggressive type from the indolent type of ATL. Areas under the curve for receiver-operating characteristic (ROC) analysis regarding the series of parameters investigated ranged from 0.75 to 0.92; this indicated relatively high accuracy in distinguishing the aggressive type from the indolent type. No malignant findings were detected in lymph node biopsies in indolent ATL patients with lymphadenopathy.
Discussion: We performed evaluation of a line of parameters of FDG-PET, thereby demonstrating their significantly high accuracy for grading malignancy in ATL patients. In particular, low accumulation of FDG in indolent ATL patients with lymphadenopathy might predict that it is not a sign of disease transformation, but rather a reactive manifestation.
Conclusion: FDG-PET/CT findings could be useful for clinically grading ATL.
Keywords: Adult T-cell leukemia; aggressive type; indolent type; metabolic tumor volume; positron emission tomography; standardized uptake value; total lesion glycolysis; volume-based parameter.