Value of FDG-PET in Prediction of Splenectomy Findings in Patients with Suspected or Known Lymphoma.

Splenectomy is frequently performed for diagnostic purposes in patients with suspected or known lymphoma, including assessment for possible transformation. The ability to predict splenectomy findings (and potentially avoid associated morbidity and mortality) would be valuable. The purpose of this study was to determine whether preoperative¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) results correlate with pathologic diagnosis from splenectomy.

Methods: One hundred sixty-five patients who had undergone a splenectomy at New York Presbyterian Hospital from January 2004 to July 2006 were identified from the pathology database. Records of these patients were searched and 11 with suspected or known lymphoma as an indication for splenectomy and who had a pre-splenectomy PET scan were identified. A nuclear medicine physician performed a blinded review and assigned each PET scan to one of the following categories based on splenic FDG standardized uptake values (SUV): low splenic metabolic activity (correlated with maximum SUV range 2-3.7), intermediate splenic metabolic activity (maximum SUV range 6–7), and high splenic metabolic activity (maximum SUV range 26–29). Findings were correlated with splenectomy pathologic diagnosis.

Results: Subjects (n=11, 4 female, 7 male) had a median age of 48 years (range 21–72); four had suspected lymphoma pre-splenectomy, while 7 had a prior diagnosis and had splenectomy for diagnostic (to rule out transformation) or other purposes. Median time between PET and splenectomy was 1.25 months. Of 5 patients with low metabolic activity on PET; three had benign findings at splenectomy and two had splenic involvement of previously known mantle cell lymphoma. Three patients had intermediate metabolic activity on PET; all subsequently demonstrated marginal zone lymphoma at splenectomy. Three patients had high metabolic activity on PET; all were found to have diffuse large B cell lymphoma at splenectomy.

Conclusions: This study to our knowledge comprises the largest series to evaluate splenic FDG-PET uptake in patients with suspected or known lymphoma, followed by subsequent pathologic confirmation. Patients with low splenic SUVs appear to be less likely to have splenic involvement of lymphoma, while intermediate and high values may correlate with lymphoma histology. Our findings support a potential role for FDG-PET as a tool for use, in conjunction with clinical and laboratory assessment, in consideration of the need for splenectomy in these settings.