Spleens With Disseminated Lymphoma Exhibit Higher Standardized Uptake Value Maximum, Metabolic Tumor Volumes, and Total Lesion Glycolysis on Fluorine‐18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Standardized uptake value maximum (SUVmax), metabolic tumor volumes (MTV), and total lesion glycolysis (TLG) are metabolic parameters used to quantify tumors detected on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). This is a subset project from a larger pilot study where dogs diagnosed with lymphoma via lymph node aspirates were staged and monitored with serial 18F-FDG PET/CT before, during, and after completion of standard of care chemotherapy. The aim of this prospective study was to evaluate metabolic parameters within the spleen in dogs with naive lymphoma and establish cutoff values for these metabolic parameters to predict lymphoma dissemination to the spleen (n = 7 dogs, 17 splenic samples). Splenic contours were performed at each time point to compare splenic cytology to splenic SUVmax, MTV, and TLG. Statistically significant receiver operating characteristic (ROC) curve-derived cutoff values were found for SUVmax (cutoff > 3.55, p ≤ 0.05) and MTV with a threshold of 1.5 SUV (cutoff > 325.7, p ≤ 0.05). Additionally, there are significantly higher mean/median splenic SUV, MTV, and TLG among dogs with lymphoma in the spleen compared to those with benign splenic cytology. Therefore, certain cutoff values for SUVmax, MTV, and TLG may be able to predict splenic dissemination. These results may allow for noninvasive staging, monitoring of therapeutic response, and evaluation for recurrence of lymphoma following remission.