Breast Imaging: Correlation Between Axillary Lymph Nodes Apparent Diffusion Coefficient and Pathological Lymphovascular Invasion in Patients With Invasive Breast Cancer.

OBJECTIVE

Together with local invasion, one of the important characteristics of cancer is its capacity to spread, resulting in metastases. Before cancer cells metastasize to a secondary site, they must first enter and spread through the blood and lymph vasculature, this is known as lymphovascular invasion (LVI). This LVI and, to a much lesser extent, perineural and neural invasion are one of the biologic prerequisites for systemic spread and metastases. To evaluate the correlation between pre-operative apparent diffusion coefficient (ADC) of the ipsilateral enlarged axillary lymph nodes (LNs) and presence of LVI on post-operative pathology, in patients with invasive breast cancer.

MATERIALS AND

METHODS

This retrospective study was approved by the institutional review board. It included 100 female patients (mean age, 49 years; range, 30-68 years) with invasive breast cancer, who underwent preoperative magnetic resonance imaging (MRI) and breast surgery. On pre-operative MRI, the ADC was calculated for the ipsilateral enlarged axillary LN. Presence or absence of LVI was assessed on post-operative histopathology. Statistical analysis was performed to investigate any correlation between the ADC value of the axillary LNs and LVI in these patients.

RESULTS

The mean ADC value of the ipsilateral enlarged axillary LNs was significantly lower in LVI positive cases compared to LVI negative cases (0.735 × 10-3 mm2/s) vs. (1.024 × 10-3 mm2/s), (p<0.001). Moreover, the mean Ki-67 in LVI positive cases was 46.12%, compared to 21.58% for LVI negative cases. This higher Ki-67 level in LVI positive cases indicates a greater degree of proliferation and thus the more aggressive nature of these tumors, and this was positively correlated with ADC values of the ipsilateral enlarged axillary LNs.

CONCLUSION

In cases of invasive breast cancer, the ADC value of the ipsilateral enlarged axillary LNs assessed on pre-operative MRI, and Ki-67 status of the tumor were significantly correlated to the LVI status on histopathological assessment. This ADC value may be useful as a predictor of axillary LN involvement, metastasis, and prognosis in invasive breast cancer.