Computed tomography image characteristics of metastatic lymph nodes in patients with squamous cell carcinoma of the head and neck

Objective: Metastatic neck nodes are commonly described as "heterogenous" or "inhomogenous" on computed tomographic (CT) images, and this remains a highly subjective issue. The purpose of this study is to justify classical criteria and to develop novel supplemental methods for diagnosing a positive neck node on CT scans. Methods: Fifty-four patients with H&N SCC were separated into two groups according to their neck nodal status. CT scan digital images were used and the lymph node borders were selected by a radiologist. Lymph node images from the pathologically proven N- (negative for cervical metastases) group were compared to the N+ (positive for cervical metastases) group. Image-analysis software, ImageJ, was used to record and compare various characteristics collected from the images. Results: The image-analysis comparisons shows, the area (size) of the lymph node in the N+ group is much larger than the N- group (474.02 VS.81.55mm²) (P<0.01). There are no significant differences with regards to distribution of pixel values between the two groups (P=0.79). The lacunarity, a parameter used to describe gappiness or inhomogeneity, of the N+ group was significantly higher than the N- group (P=0.026). Conclusions: While size of the lymph node remains an important factor in the interpretation of a clinically suspicious lymph node metastasis on CT scan images, the distribution of pixel values could not clarify a heterogeneous state. Nevertheless, 'lacunarity' proves to be a more accurate parameter which correlates better to the subjective heterogeneity.