[Differential diagnosis of lymph nodes in oral-maxillary regions by ultrasonography]

We divided lymph nodes into three groups, those that are normal, those with lymphadenitis, and those that are metastatic. We analyzed these groups based on their ultrasonographic images by measuring maximum cross-section, L/T ratio, coutour, internal echo images, and posterior echo images, and examined the results statistically. In this study, especially for images relevant to internal echoes, the sound wave reflected from the interior of the lymph nodes was taken as aggregate of bright spots, which were analyzed in terms of the following aspects: texture or size, distribution pattern, and brightness. The results are as follows. (1) The size of the lymph nodes is 7.1 +/- 1.7 mm (mean +/- S.D.) for normal, 10.6 +/- 3.8 mm for lymphadenitis, and 13.1 +/- 7.3 mm for metastatic. (2) The L/T ratio is 0.55 +/- 0.16 for normal, 0.64 +/- 0.21 for lymphadenitis, and 0.83 +/- 0.15 for metastatic. (3) The increment of the lymph node size and the variation in L/T ratio are plotted in the disperation diagram. It was concluded that differential diagnosis would be difficult only based on the size and L/T ratio of the lymph nodes under study. (4) The contour appears indistinct in normal lymph nodes, especially in their lateral aspect, while it is distinct around the whole circumference in lymph nodes with inflammation or metastatic cancer. (5) From the analysis based on texture, distribution, and brightness of the echo images of the interior of lymph nodes, it was concluded that in metastatic lymph nodes, aggregated echoes are distributed unevenly, and their brightness is similar to that of adjacent tissues. 6. Posterior echo images were unique findings that showed acute lymphadenitis. Those analytical results based on the three types of findings were rated and submitted to T-tests, which showed that there is a significant difference at a level of 5% among normal lymph nodes, those with inflammatory changes, and those with metastases.(ABSTRACT TRUNCATED AT 250 WORDS)