Sonografic evaluation of oxygenation in head and neck cancer

Background: Tumor oxygenation is an important aspect of radiosensitivity. The authors describe a new method for a non-invasive assessment of tumor oxygenation in head and neck cancer. Patients and Methods: A group of 20 patients with neck metastases of squamous cell cancer of the head and neck region was surveyed. At first a pO(2)-polarography was performed in the metastatic cervical nodes to investigate the tissue oxygenation. In a second step, the vascularisation of these nodes was visualised by color duplex sonography. In order to evaluate the extent of vascularisation in these nodes, the density of color pixels was quantified by a custom-made software program. The color pixel density and the pO(2) values were correlated and the statistic significance was calculated by Pearson's test. Results: The mean vascularisation as evaluated by the means of color duplex sonography was 7.78% [95%CI 6.04-9.51]. The interindividual pO(2) values in the stroma of metastatic lymph nodes ranged between 9.0 and 27.4 mmHg (16.6 [95% CI 14.06-19.13]). The mean values of pO(2)-fractions <2.5/<5.0/10 mm Hg were 32.25 %, 44.25 % and 53.29 % respectively. The median value of the pO(2)-fraction was 10.49 % [95 % CI 7.13 - 13.85]. The vascularisation as evaluated by color pixel density showed a statistically significant correlation with the pO(2)-fractions < 5.0 and < 10 mmHg (p < 0.045 and < 0.0001) and with the mean (p < 0.002) and median values of tissue PO2 values (p < 0.0001) in polarography. Conclusion: The results in a limited number of patients suggest, that the proposed sonographic method allows a reliable non-invasive evaluation of tissue oxygenation in cervical metastases of squamous cell head and neck cancers.