The relationship between vascularity within cervical lymph nodes and lymph node size among oral cancer patients using colour doppler ultrasound

Background: Colour Doppler Ultrasonography (CDUS) has increased amount of information that can be obtained during examination of the cervical lymph nodes. Vascularity of the lymph node helps in diagnosing the cause of lymphadenopathy as vascularity is directly related to the actual pathology such as oral cancer. The aim of this study was to quantitatively evaluate the relationship between vascularity of lymph nodes and lymph node size on Color Doppler Ultrasound images of the patients with oral cancer. Material and Methods: 30 subjects taken from the cancer hospital with the age range of 20 to 75 years. CDUS evaluation of the cervical lymph nodes was performed on every patient. The vascular index defined as the number of pixels in the flow signals divided by the number of pixels in the whole lymph node, presented as a percentage. The number of isolated flow signal units in the lymph node parenchyma was counted by using Adobe Photoshop CS5 extended version. Isolated flow signal units of <3 pixels were excluded as noise signals. The scattering index defined as the number of isolated flow signal units in the lymph node parenchyma. The following lymph node size classification was considered for this study i.e. Group 1, 4-5.9 mm; Group 2, 6-7.9 mm; Group 3, 8-9.9 mm; and Group 4, ≥10 mm (median diameter, 12 mm; range, 10-27 mm). Results: Pair-wise comparison of mean Vascular Index between Lymph Node size classifications and mean Scattering Index between Lymph Node size classifications was done. There was a statistically significant difference seen in the values of Vascular Index between all Lymph Node (LN) classification (p<0.05) with the highest value with Group 1, followed by Group 2 then Group 3 and least with Group 4 and there was a statistically highly significant difference in the mean Scattering Index (SI) with various LN classification (p<0.01) with the highest value with Group 4, followed by Group 3 then Group 2 and least with Group 1. Conclusions: The metastatic lymph node size increases, the Vascular Index (VI) of metastatic lymph nodes decreases. Lymph node size of metastatic lymph nodes has an indirect relationship with the Vascular Index (VI). Thus, an increase in the vascular index was considered to be a useful Doppler ultrasound finding for detecting metastasis in small lymph nodes Thus, the CDUS could provide a potential means of visualizing and sampling suspicious carcinoma lesions in high-risk populations.