Pre-therapy 18F-FDG PET quantitative parameters help in predicting the response to radioimmunotherapy in non-Hodgkin lymphoma

Purpose Radioimmunotherapy (RIT) is a new treatment option for patients with non-Hodgkin lymphoma (NHL). Response to RIT currently remains difficult to predict using conventional prognostic factors and could be refined using functional imaging. The goal of this work is to evaluate the value of 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting response to Yttrium 90-labeled monoclonal antibodies for patients with NHL. Methods Thirty-five patients with NHL who had undergone 18 F-FDG PET prior to RIT with either 90 Y-ibritumomab tiuxetan (group A; n = 17) or 90 Y-epratuzumab tetraxetan (group B; n = 18) were included in this retrospective study. Four functional criteria were determined for each tumour lesion in a given patient: maximum and mean standard uptake values (SUVmax and SUVmean), functional lesion volume (LVol) and total lesion glycolysis (TLG, product of the volume and the SUVmean). For each patient, we determined highest SUVmax and SUVmean, cumulative TLG (TLGcum) and sum of all LVol (TVol) and compared their predictive value on response (complete or partial response according to IWC) to RIT with those of conventional prognostic factors in group A and B. Results A total of 154 lesions were analysed. Nineteen patients (54%) responded to RIT according to IWC. In group A, response rate was 54, 75 and 75% in patients with a SUV max