Role of diffusion-weighted MRI: predicting axillary lymph node metastases in breast cancer.
BACKGROUND
Ultrasound (US) is probably the standard imaging procedure in most centers, and US-guided fine needle aspiration can be added if suspicious lymph nodes are found. However, US-guided fine needle aspiration is an invasive method to diagnose a metastasis and has showed relatively low sensitivity. In general, diffusion-weighted (DW) magnetic resonance imaging (MRI) has become an emerging technique for discriminating benign from malignant breast lesions in a short imaging acquisition time.


OBJECTIVE
To evaluate the potential for using DW MRI with an apparent diffusion coefficient (ADC) value to predict axillary lymph node metastases in patients with invasive breast cancer.


METHODS
This study enrolled 110 axillary lymph nodes from 110 consecutive women who were diagnosed with invasive breast cancer for preoperative breast MRI and US. The largest enhancing ipsilateral axillary lymph nodes were included in this study, and benign and metastatic axillary lymph nodes were compared according to the pathologic reports. The cut-off ADC value to differentiate between benign and metastatic axillary lymph nodes was evaluated with receiver-operating characteristic curve analysis. Diagnostic performance of ultrasound and DW MRI was calculated for enhancing lymph node in dynamic contrast-enhanced MRI.


RESULTS
Nodal metastases were documented in 68 (62%) axillary lymph nodes. The mean size of metastatic axillary lymph nodes was larger than that of benign axillary lymph nodes (15.5 mm vs. 10.9 mm, P < 0.001). The mean ADC value (0.69 × 10(-3 )mm(2)/s) of the metastases was significantly lower than that of the benign axillary lymph nodes (1.04 × 10(-3 )mm(2)/s) (P < 0.001). The ADC value cut-off between metastatic and benign axillary lymph nodes was 0.90 × 10(-3 )mm(2)/s. Using ADC cut-off, sensitivity, specificity, and accuracy of DW MRI were 100%, 83.3%, and 93.6%, respectively. The sensitivity, specificity, and accuracy of US showed 94.1%, 54.8%, and 79.1%, respectively.


CONCLUSIONS
DW MRI of axillary lymph nodes can provide reliable information for the differentiation of benign from metastatic axillary lymph nodes in invasive breast cancer patients.
Department of Radiology, Ewha Womans University, School of Medicine, Seoul, Republic of Korea Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Jin
J
Chung
Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Ji Hyun
JH
Youk
Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Jeong-Ah
JA
Kim
Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Hye Mi
HM
Gweon
Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Eun-Kyung
EK
Kim
Department of Nuclear Medicine, Yonsei University, College of Medicine, Seoul, Republic of Korea.
Young Hoon
YH
Ryu
Department of Radiology, Yonsei University, College of Medicine, Seoul, Republic of Korea ejsonrd@yuhs.ac.
Eun Ju
EJ
Son
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016217:Ultrasonography, Mammary / Q000379:methods
D003287:Contrast Media; D019786:Gadolinium DTPA
Breast cancer; apparent diffusion coefficient (ADC); axillary lymph node; diffusion; magnetic resonance imaging (MRI); ultrasound (US)