Utility of 18F-fluorodeoxyglucose PET-CT scan in detecting bone marrow involvement in lymphoma

Background & objectives: Evaluation of bone marrow infiltration in lymphoma is usually done by bone marrow biopsy (BMB). This study analyzed the utility of F-18-fluorodeoxyglucose positron emission tomography/computerized tomography (F-18-FDG PET/CT) to detect bone marrow involvement (BMI) compared to BMB. Methods: Treatment-naive lymphoma patients underwent both F-18-FDG PET/CT scan and BMB before treatment initiation. BMI detected on PET/CT was compared with BMB. Results: The study population consisted of 80 patients and comprised 37 Hodgkin's lymphoma (HL) patients, 30 aggressive non-HL (NHL) and 13 indolent NHL patients. The majority of the aggressive NHLs were diffuse large B-cell lymphoma (20/30) and major indolent lymphoma was follicular lymphoma (5/13). When compared to BMB, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of focal (+/- diffuse) marrow FDG uptake on F-18-FDG PET/CT were 100, 61.3, 33.3 and 100 per cent, respectively, for HL; 100, 65.4, 30.8 and 100 per cent, respectively, for aggressive NHL and 75, 80, 85.7 and 66.7 per cent, respectively, for indolent NHL. When comparing marrow involvement on F-18-FDG PET/CT to baseline BMB and/or resolution of bone marrow FDG uptake at interim/end-of-treatment F-18-FDG PET/CT, the sensitivity, specificity, PPV and NPV were 100 per cent each for HL and aggressive NHL and 77.3, 100, 100 and 66.7 per cent, respectively, for indolent NHL. Interpretation & conclusions: F-18-FDG PET/CT has a good sensitivity and NPV for detecting BMI in HL and aggressive lymphoma. The low specificity and PPV improved if marrow uptake pattern on interim or end-of-treatment F-18-FDG PET/CT scan was analyzed. In patients with HL who are staged with F-18-FDG PET/CT at baseline and followed up with an interim/end-of-treatment PET/CT, baseline BMB may be avoided. For all other lymphoma subtypes, BMB may be essential if there is no marrow FDG uptake on PET/CT scan performed at baseline.