Diagnostic efficiency of semi-quantitative analysis by mean counting ratio method of thyroid scan / 中国医师进修杂志

ABSTRACT

Objective:To assess the diagnostic efficient of mean counting ratio method, and to simplify and improve the semi-quantitative method of defining excessive uptake of thyroid nuclides.Methods:One hundred and nine imaging results of thyroid scan in Dalian Municipal Central Hospital from April 2017 to January 2018 were delineated the FOI by two experienced deputy chief physicians and the ratio of average counts per unit area was determined. Clinical diagnosis of hyperthyroidism was used as gold standard, and receptor operation characteristic (ROC) curve was drawn and the optimal diagnostic threshold was calculated. The sensitivity, specificity, accuracy, positive and negative predictive values were calculated and the consistency of the two physicians′ diagnosis was analyzed.Results:The best diagnostic threshold was 6.94 by drawing ROC curve from the measurements of two physicians. The value greater than this was used as a criterion to define the excessive uptake of technetium in thyroid gland. For doctor 1, the sensitivity, specificity and accuracy of differential diagnosis of hyperthyroidism based on diagnostic threshold were 86.0%(37/43), 100.0%(66/66) and 95.5%(103/109), respectively. For doctors 2, they were 88.4%(38/43), 100.0%(66/66) and 95.4%(104/109), respectively. The concordance rate was 96.6%(86/89), interclass correlation coefficient (ICC) was 0.98.Conclusions:Average counting ratio method provides reliable semi-quantitative cut off value for differential diagnosis of high Tc uptake. It has good application value. Different physicians independently complete the semi-quantitative analysis of Tc uptake by average counting ratio method, which has good consistency. In practice, it is simpler and easier than the thyroid/background ratio method.