Suvmax in 18-Fluorodeoxyglucose PET/CT Potentially Predict the Estimation of a Positive Biopsy in Cases of Lymphoma

Introduction

The significance of 18-fluorodeoxyglucose PET/CT for predicting the estimation of a positive biopsy in cases of lymphoma is unknown. Diagnosis of lymphoma is based on a lymph node biopsy, however, the use of 18-fluorodeoxyglucose PET/CT for selecting a biopsy site that would provide the best the yield for accurate diagnosis remains unknown.

Patients and Methods

Data on 165 patients with initial suspicion of lymphoma that underwent PET/CT scans and biopsy as part of their initial evaluation were prospectively collected and reviewed. Standadized uptake value (SUVmax) of the biopsy site and others was collected from radiology reports. The association between the SUVmax on FDG-PET/CT before excision and the estimation of lymphoma diagnosis at biopsy was examined using a receiver operating characteristics curve analysis (ROC).

Results

159/165 (84.5%) cases suspected of lymphoma underwent PET/CT scan performed prior excisional/FNA biopsy. Ninety six cases were diagnosed of diffuse large B cell lymphoma (DLBCL), 24 follicular lymphoma, 34 Hodgkin lymphoma, 15 plasmablastic lymphomas, and 6 marginal zone lymphoma. Receiver operating characteristics curve analysis demonstrated an area under the curve (AUC) of 0.6 with a borderline p-value of 0.06, which reached level of significance when the methodology of diagnosis only involved fine needle aspiration (FNA, AUC: 0.645, p= 0.05) or when the analysis was performed in patients with a diagnosis of follicular lymphoma (AUC:0.8, p<0.05). We identified several factors that influence SUVmax intensity, which included lymphoma subtype, stage and LDH. Consistent with prior reviews, tumor type was associated with higher SUVmax withDLBCL and plasmablastic with the highest SUV, followed by Hodgkin lymphoma and low grade lymphoma (p<0.05). Tumors with advance stage (stage 4) and high LDH levels were also associated with higher SUVmax.

Conclusion

SUVmax on FDG-PET/CT is potentially useful for guiding biopsy sites that will provide the best yield to diagnose lymphoma. SUVmax is particularly useful to diagnose lymphoma when FNA is performed as diagnostic procedure of choice. We identified that tumor type, stage and LDH can affect SUV intensity. Performing a Receiver operating characteristics curve analysis of the SUVmax on FDG-PET/CT in a larger samples size is warranted for defining thresholds that predict the estimation of a positive biopsy.