Rationale and Objectives
Our objective is to determine an optimum standardized uptake value (SUV) threshold for identifying regional nodal metastasis on 18 fluoro-deoxy-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) studies of patients with inflammatory breast cancer (IBC).
Materials and Methods
A database search was performed of newly diagnosed IBC patients who had 18F-FDG PET/CT performed at the time of diagnosis in a single institution between January 1, 2001 and September 30, 2009. Three radiologists blinded to the histopathology of the regional lymph nodes retrospectively analyzed all 18F-FDG PET/CT images by measuring the SUVmax in visually abnormal nodes. The accuracy of 18F-FDG PET/CT image interpretation was correlated with histopathology where available. A receiver operating characteristic curve (ROC) analysis was performed to assess the diagnostic performance of PET/CT. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated using 3 different SUV cutoff values (2.0, 2.5, 3.0).
Results
A total of 888 regional nodal basins, including bilateral axillary, infraclavicular, internal mammary and supraclavicular lymph nodes were evaluated in 111 patients with a mean age of 56 years. Of the 888 nodal basins, 625 (70%) were negative and 263 (30%) were positive for metastasis. Malignant lymph nodes had significantly higher SUVmax than benign lymph nodes (p <0.0001). An SUVmax of 2.0 showed the highest overall sensitivity (89%) and specificity (99%) for the diagnosis of malignant disease.
Conclusion
SUVmax of regional lymph nodes on 18F-FDG PET/CT may help differentiate benign and malignant lymph nodes in IBC patients. SUV cutoff 2 provided the best accuracy in identifying regional nodal metastasis in this patient population.