Francesca Fornasa MD, Presenter: Nothing to Disclose

Maria Stella Laveneziana, Abstract Co-Author: Nothing to Disclose

Elisa Pomaro, Abstract Co-Author: Nothing to Disclose

To assess the accuracy of Diffusion-weighted Magnetic Resonance Imaging (DWI) in differentiating between metastatic and metastasis-free axillary lymph nodes in patients with breast cancer.

250 consecutive patients with histologically proven breast cancer underwent breast MRI (1.5 T; 4-channel coil) within two weeks prior to axillary dissection. The axilla ipsilateral to the tumor was included into the field of view; if a lymph node was detected with morphological features (short axis = 7 mm or more) deeming malignancy likely, DWI (b values: 0 and 800 mm/sec2) was performed and a lymph nodal Apparent Diffusion Coefficient (ADC) was obtained through the average of three different measurements. Patients were included if histology after axillary dissection demonstrated, in the lymph node evaluated with DWI, either a metastasis larger than 5 mm or the absence of metastases. 43 patients (age range: 38-79 years) meeting the above mentioned criteria were included in this study. The statistical significance of the difference between the ADC values in metastatic and non-metastatic lymph nodes was determined using the Student’s t-test.

At histological examination 19 patients had one lymph node with a metastasis larger than 5 mm and 24 had not. The ADC values of the metastatic lymph nodes (mean: 0.878 mm2/sec; range: 0.30-1.20) were significantly lower (p<0.001) than those of the metastasis-free lymph nodes (mean: 1.494; range: 0.60-2.50). With a cutoff value of 1.09 mm2/sec (two false positive; one false negative result) DWI proved 94.7% sensitive, 91.7% specific and 93.0% accurate in the diagnosis of lymph node metastasis.

DWI is a reliable method in the differential diagnosis between metastatic and metastasis-free axillary lymph nodes in patients with breast cancer.  

In the evaluation of axillary lymph nodes none of the current non-invasive procedures has optimal accuracy, while DWI (being easy, cheap, safe and reliable) is a promising diagnostic tool.

Fornasa, F, Laveneziana, M, Pomaro, E, Can Diffusion-weighted Magnetic Resonance Imaging Differentiate between Metastatic and Nonmetastatic Axillary Lymph Nodes in Patients with Breast Cancer?.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002562.html