Accuracy of computed tomography perfusion in assessing metastatic involvement of enlarged axillary lymph nodes in patients with breast cancer

Abstract

Introduction: The purpose of this study was to evaluate the diagnostic accuracy of computed tomography (CT) perfusion in differentiating metastatic from inflammatory enlarged axillary lymph nodes in patients with breast cancer.

Methods: Twenty-five patients with 26 locally advanced breast tumors and clinically palpable axillary lymph nodes underwent dynamic multi-detector CT (LightSpeed 16; General Electric Company) at one scan per second for 150 seconds at the same table position after 40 ml intravenous contrast injection at 4.0 ml/second. Semi-automatic calculation of values of perfusion parameters - blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS) - was performed. Results were compared with pathology and with Her-2/neu and Ki-67 levels in a surgical specimen of the primary tumor.

Results: Examined lymph nodes were inflammatory in 8 cases and metastatic in 18. Mean values of perfusion parameters in inflammatory and metastatic nodes, respectively, were BF of 76.18 (confidence interval [CI], 31.53) and 161.60 (CI, 40.94) ml/100 mg per minute (p < 0.05), BV of 5.81 (CI, 2.50) and 9.15 (CI, 3.02) ml/100 mg (not significant [n.s.]), MTT of 6.80 (CI, 1.55) and 5.50 (CI, 1.84) seconds (p = 0.07), and PS of 25.82 (CI, 4.62) and 25.96 (CI, 7.47) ml/100 mg per minute (n.s.). Size of nodes, stage of breast cancer, Ki-67 and Her-2/neu levels in breast cancer, and expression of primary tumor activity were not correlated to any perfusion parameter in metastatic nodes.

Conclusion: CT perfusion might be an effective tool for studying enlarged axillary lymph nodes in patients with breast cancer. It gives information on vascularization of lymph nodes, helping to understand the changes occurring when neoplastic cells implant in lymph nodes.

Figure 1

Image from one of the slices obtained by dynamic computed tomography centered on the palpable axillary node in patient AF with right breast carcinoma. A region of interest (ROI) was manually drawn along the margins of the target node (3). ROIs 1 and 2 were positioned in the axillary artery and vein. They were chosen with a very small area, as suggested by the software designer, to avoid partial volume effects. ROI 4 was drawn in the Teres major muscle for control.

Figure 2

Map of perfusion of patient in Figure 1. The colored scale perfusion map designed using software shows how the perfusion of the target node is similar to that of the muscle. At post-surgical pathology, no metastases were found in the node.

Figure 3

Colored map of blood volume (BV) in a patient with right breast cancer and omolateral palpable node. Both the primary tumor (outlined by region of interest [ROI] 5) and the target node (outlined by ROI 6) are visible on this slice. High values of BV are depicted both in the primary tumor and in the target node. At post-surgical pathology, the lymph node was determined to be metastatic.