Different approaches to volume assessment of lymph nodes in CT Scans of HNSCC in comparison with a real gold standard

Objectives: Volume assessment in head and neck squamous cell carcinoma (HNSCC) becomes an increasing important clinical parameter in treatment planning and response control. Various authors showed a significant impact of tumor volume on outcome and local control. In this study we compared the “gold standard”, the diameter based approach, with segmentation based approaches Methods: The segmentations were based on CT scans of 4 patients with HNSCC undergoing neck dissection as part of their treatment. These scans were taken during staging and a total of 20 lymph nodes were segmented. They were selected by size and location close to reproducible anatomical structures. The true volumes were measured by water displacement. Results: Pearson’s correlation index shows a higher correlation of the diameter generated volumes (r=0.723) than results generated via segmentation (r=0.527) with the true volumes. Nonetheless diameter generated volumes show clearly too high volumes at 146.8% (Confidence Interval: 115.8% – 186.1%). Volumes generated with the segmentation are at 116.5% (Confidence Interval: 93.9% – 144.7%). Conclusions: The data show a higher reliability of volumes estimated by the segmentation based approach than the widely used diameter based approach.