A novel method of doppler signal quantification for metastatic neck node evaluation

Problem: Vascularization and oxygenation are important factors for radiosensitivity. The authors investigate the use of a novel ultrasound technique for the assessment of vascularization and oxygenation in metastatic neck nodes. Methods: Seventeen patients with neck metastases of squamous cell head and neck cancer were investigated by Color Duplex sonography and polarography. Intranodal perfusion was measured by a novel technique using a dynamic signal quantification (Pixelfux). With this approach perfusion intensity, perfused area, flow velocity, resistance index (RI), and pulsatility index (PI) could be evaluated in a predefined region of interest. PO2 was measured in the same nodes with polarography. The data were correlated using Pearson‘s test. Results: In metastatic lymph nodes the hypoxic fraction <10 mmHg demonstrated a significantly inverse correlation with the intranodal perfusion (r = 0.54, P < 0.024). Nodes with a perfusion velocity <0.05 cm/sec had larger hypoxic areas (P < 0.006). Statistically significant differences existed between nodes in stage N1 and N2/3 for PI (P < 0.028) and RI (P < 0.048). Conclusion: The new sonographic technique demonstrates a significant correlation between tumor perfusion and oxygenation. This noninvasive technique allows not only the assessment of size, localization, and shape in neck nodes but also an evaluation of functionally important tumoral parameters. Significance: The method offers novel noninvasive means for monitoring perfusion and oxygenation of tumors via commonly available ultrasound equipment. It can be helpful for therapy monitoring in head and neck cancers. Support: Chameleon Software Corp. provided the Pixelflux software application free of charge for this study.