Investigation of FDG-PET/CT imaging to guide biopsies in the detection of histological transformation of indolent lymphoma

Abstract

Positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) has been successfully evaluated in the management of non-Hodgkin's lymphoma (NHL).1-3 Histological transformation (HT) of indolent lymphoma is a dramatic event that occurs in 5-10% of the patients and carries a dismal prognosis.4,5 Previous studies prove that indolent lymphoma entities show a lower FDG uptake when compared with aggressive lymphomas.6-8 We therefore postulated that FDG-PET/CT identifies aggressive transformation sites and can guide biopsies.

18F-FDG or 3′-Deoxy-3′-18F-Fluorothymidine to Detect Transformation of Follicular Lymphoma

“…Other studies using 18 F-FDG in this setting included mixtures of several lymphoma subtypes, and this heterogeneity may have contributed to the lack of consistency of thresholds of highest SUV max or SUV range (9)(10)(11). For example, our median 18 F-FDG highest SUV max for FL (10.9, Table 2) is higher than the threshold of 10 proposed by Schöder et al, excluding indolent lymphoma with a specificity of 81% (9).…”

“…At that moment the diagnostic accuracy is optimal; moreover, given the high intraindividual heterogeneity in uptake, PET will be helpful in the decision of where to biopsy. Although no study showed biopsies of all lymph nodes in a patient, we share the opinion that the lymph node with the highest uptake is most likely the transformed lymph node, also considering data showing uptake correlating with aggressiveness (9)(10)(11)16). …”

“…Therefore, a high uptake in an indolent lymphoma could support the suspicion of transformation. However, there is a considerable overlap in 18 F-FDG uptake between aggressive and indolent lymphomas, potentially impairing its utility to detect transformation (9)(10)(11). To overcome this problem, alternative tracers might be useful.…”

Prognostic Factors in Follicular Lymphoma in the Rituximab Era: How to Identify a High-Risk Patient?

“…The introduction of this diagnostic modality required development of new "revised" criteria for treatment response 44 . Although the use of PET/CT in FL is still in its infancy, the available studies suggest that it is of great value in the identification of patients with FL transformation to aggressive lymphoma 45,46 . On the other hand, the initial assumption that the level of FDG accumulation closely correlates with the level of aggressiveness (histologic subtype) of lymphoma was not confirmed 47,48 .…”

Diagnostic and Treatment Response Imaging in Lymphomas

“…Histological transformation of indolent lymphoma occurs in 20 -30% of the patients. Recent study has shown that FDG-PET can be used as an accurate guide for biopsies in suspected transformed tissues (Bodet-Milin C et al, 2008). The standardized uptake value varies considerably in different tumors of the same lymphoma patients, and biopsies should be performed in the site with the maximum standardized uptake value of the whole body (the highest malignancy) that represents the malignancy of the disease (Bodet-Milin C et al, 2008;.…”