Characterization of ex vivo healthy human axillary lymph nodes with high resolution 7 Tesla MRI.

OBJECTIVE

To characterize ex vivo healthy human axillary lymph nodes on 7 Tesla MRI and to correlate the findings with pathological analysis as a first step towards non-invasive staging of breast cancer patients in the future.

METHODS

Four axillary lymph node dissection (ALND) specimens from 2 autopsy patients, who had no cancer, were examined on a clinical 7 Tesla MRI system. For morphological analysis a 3D T1-weighted fat-suppressed fast-field-echo [isotropic resolution 180 μm] was acquired. For quantitative analyses 2D T1-, 3D T2-, T2*- and diffusion-weighted images were acquired. The ALNDs were mapped and stained for precise correlation of MRI to pathology. Nodes were sliced in 3 μm sections, Haematoxylin & Eosin stained, and examined by an experienced pathologist.

RESULTS

MRI detected all 45 nodes and 6 additional nodes that were not detected at pathological analysis. B-cell follicles, efferent- and afferent lymph vessels and blood vessels were identified. Mean T1, T2, T2*, ADC values (± standard deviation) were 944 ± 113 ms, 32 ± 2 ms, 16 ± 2 ms, 0.39 ± 0.09·10⁻³ mm²/s, respectively.

CONCLUSIONS

7 Tesla MRI of ex vivo human axillary lymph nodes correlated well with pathology. MRI detected all nodes present in the specimens and allowed visualization of fine structural detail. Pathology-correlated quantitative MRI data are presented.