Mediastinal lymph nodes: assessment with diffusion-weighted MR imaging.

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Mediastinal lymph node assessment is crucial for staging thoracic malignancies.
• Distinguishing between malignant and benign mediastinal lymph nodes can be challenging.
• Diffusion-weighted magnetic resonance imaging (DW-MRI) offers insights into tissue cellularity.

Purpose of the Study:

• To prospectively evaluate the utility of diffusion-weighted MRI in differentiating malignant from benign mediastinal lymph nodes.
• To correlate apparent diffusion coefficient (ADC) values and signal intensities with lymph node pathology.

Main Methods:

• Thirty-five patients with 91 mediastinal lymph nodes underwent 1.5T DW-MRI prior to surgical staging.
• DW-MRI images were acquired using a single-shot echo-planar sequence with b-factors of 50 and 400 s/mm(2).
• Apparent diffusion coefficient (ADC) values and signal intensities were analyzed and compared to pathological findings.

Main Results:

• Metastatic lymph nodes exhibited significantly lower ADC values (1.012 ± 0.025 x 10(-3) mm(2)/s) compared to benign nodes (1.511 ± 0.075 x 10(-3) mm(2)/s).
• Malignant nodes showed varied signal intensities on ADC maps (hyperintense, hypointense, mixed).
• Benign nodes predominantly displayed hyperintense signals on ADC maps.

Conclusions:

• Diffusion-weighted MRI, utilizing ADC values and signal intensity patterns, shows promise in differentiating malignant and benign mediastinal lymph nodes.
• DW-MRI can serve as a valuable non-invasive tool in the diagnostic workup of mediastinal lymphadenopathy.