[Analysis of ultrasound B-mode histogram in thyroid tumors]

B-mode histograms of preoperative ultrasound texture were correlated to final pathological diagnoses and findings in 50 thyroid tumors (18 follicular adenomas, 6 follicular carcinomas and 26 papillary carcinomas) and 10 cases without any thyroid disease. Histograms were taken in the region of interest (ROI) and in the control area of the normal thyroid tissue. The following parameters, after subtracting the statistics of the control region from that of ROI, were evaluated; the difference of mean (D1), of standard deviation (D2), of skewness (D3), and of krutosis (D4). Likewise, Maharanobis distance (MD) was also studied. D1 was lower in papillary carcinomas than in follicular adenomas, and diminished by the relative proportion of some pathological findings, D2 and D3 of papillary carcinomas was higher than those of follicular adenomas. MD, having a significant correlation to D1 (r = -.8), revealed similar relationship with pathology as that of D1. No significant difference was observed between normal thyroid tissue and follicular adenoma, nor between follicular adenoma and follicular carcinoma in any parameter. MD showed the best correlation to malignancy. The criterion which judges the the tumor with D1 less than -2.5, or D2 more than 1 to be malignant, was expected to have sensitivity of 83% and specificity of 88%.