A Comparison of the Diagnostic Value of Positron Emission Tomography/Computed Tomography and Ultrasound for the Detection of Metastatic Axillary Nodal Disease in Treatment-Naive Breast Cancer.

ABSTRACT: The objective of this study was to describe the diagnostic value of positron emission tomography/computed tomography (PET/CT) and ultrasound (US) for identifying metastatic axillary disease in primary breast cancer. This is a retrospective review of 240 patients with treatment-naive unilateral primary breast cancer of at least stage T2. Eighty-five patients met our inclusion criteria. Initial whole-body PET/CT and axillary US examinations were reviewed and compared with the criterion standard of fine-needle aspiration cytology. Sensitivity, accuracy, and positive predictive value (PPV) for each modality were computed. Because of all positive US cases, specificity and negative predictive value of US were not determined. Sensitivity and accuracy between modalities were compared using McNemar test. The majority of the patients were White women with clinical inflammatory breast cancer and with histologically invasive ductal carcinoma. The most common tumor and nodal stage was T4N3. The tumors were predominantly estrogen receptor positive, progesterone receptor negative, and human epidermal growth factor receptor 2 negative. The sensitivities of PET/CT and US were 96.2% and 100%, respectively. The accuracies for PET/CT and US were 91.8% and 94.1%, respectively. The PPV for PET/CT was 95.1%, and for US, the PPV was 94.1%. No significant difference in sensitivity or accuracy was shown between PET/CT and US for the diagnosis of metastatic axillary nodal disease. Three of 85 cases showed discordance between negative PET/CT and positive US and fine-needle aspiration cytology.