Relationship between semiquantitative 18F-fluorodeoxyglucose positron emission tomography metrics and necrosis in classical Hodgkin lymphoma.

Semiquantitative 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) parameters have been proposed as prognostic markers in classical Hodgkin lymphoma (cHL). In non-Hodgkin lymphoma necrosis as assessed by 18F-FDG PET or computed tomography (CT) (necrosisvisual) correlates with an adverse prognosis. We investigated whether semiquantitative 18F-FDG PET metrics correlate with necrosisvisual, determined the incidence of necrosisvisual and explored the prognostic impact of these factors in cHL. From 87 cHL cases treated with ABVD, (escalated) BEACOPP or CHOP chemotherapy between 2010 and 2017, 71 had both a NEDPAS/EARL accredited 18F-FDG PET and a contrast enhanced CT scan. Semiquantitative 18F-FDG PET parameters were determined using Hermes Hybrid 3D software. Necrosisvisual, defined by photopenic tumor areas on 18F-FDG PET and attenuation values between 10 and 30 Hounsfield units (HUs) on CT, was assessed blinded to outcome. Univariate Cox regression survival analyses of progression free survival (PFS) were performed. Necrosisvisual was observed in 18.3% of cHL patients. Bulky disease (tumor mass >10 cm in any direction) (P = 0.002) and TLG (P = 0.041) but no other semiquantitative parameters were significantly associated with necrosisvisual. In exploratory univariate survival analysis for PFS the covariates IPS, bulky disease, MTV and TLG were prognostic, while necrosisvisual was not.