Quantitative evaluation of interim positron emission tomography in peripheral T-cell lymphoma

BACKGROUND: Interim [(18)F]fluoro-deoxyglucose-positron emission tomography predicts outcome in peripheral T-cell lymphoma (PTCL). We compared two quantitative evaluation methods. METHODS: Interim scans from 43 patients with anaplastic lymphoma kinase-negative PTCL from the ‘Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas’ trial were re-analyzed by qPET (relating residual lymphoma-related uptake to liver uptake) and ∆SUV(max) (relating interim scan to baseline scan). The endpoint was progression-free survival. RESULTS: qPET and ∆SUV(max) were closely correlated (Pearson’s r = 0.627). Up to the 60(th) percentile of values ranked by increasing residual activity, the positive predictive value for progression or death increased from 60 to 95%, with stable negative predictive values (NPV) of 60%. Beyond the 60(th) percentile, the NPV decreased to 40%. qPET ≥ 2 and ∆SUV(max) < 50% identified high-risk populations comprising 41.9% and 39.5% of patients, with 3-year progression-free survival rates of 5.6% (95% confidence interval, 0.8–37.3) and 0%, respectively, as compared to 63.7% (47.4–85.8) and 61.3% (45.1–83.3) in low-risk patients. CONCLUSIONS: qPET and ∆SUV(max) identify large fractions of PTCL patients destined to experience treatment failure. qPET may be preferred because it requires a single PET scan, halving the diagnostic effort. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13550-021-00827-1.