Evaluation of the Most Important Ultrasound Parameters in Detection of Thyromegaly and its Relationship with Anthropometric Factors

Abstract

Background: Approximately, 200 million people suffer from thyroid disorders worldwide. Thyromegaly is a disorder in which the thyroid gland becomes abnormally enlarged. High-resolution ultrasound of the thyroid is a useful diagnostic method for assessing thyroid disorders, including thyromegaly. To investigate the thyromegaly, the thyroid lobe dimensions are measured separately using an ultrasound device and, the thyroid volume is estimated using a formula which is time-consuming process. Besides, thyroid volume depends on a variety of factors such as age, sex, anthropometric parameters, and genetic factors. Objectives: The aim of the present study is to find the most important ultrasound parameters measured to increase the rate of thyromegaly detection and also to find the relationship between thyroid volume and some anthropometric characteristics in the study population. Methods: A total of 131 people were referred to the Ultrasound Department of Imam Reza Hospital in Kermanshah, Iran during July 2017 and 2019, and after recording the anthropometric characteristics, thyroid ultrasound was taken. Thyroid dimensions including longitudinal (L) and anterior-posterior or depth (AP), and width (W) diameter of the thyroid lobes and isthmus were measured and thyroid volume was calculated using the ellipsoid formula. According to the opinion of a fellow radiologist and considering cut-off point of volume (11.1 for women and 11.6 for men), individuals were divided into two groups: Case or thyromegaly (n = 69) and control or normal group (n = 62), and statistical analysis was then carried out. Results: Statistical analysis showed that the mean weight, Body Mass Index (BMI), thyroid dimensions, and total thyroid volume were significantly higher in the case group than the control group (P < 0.05). In the case group, only the mean width of the right lobe is significantly larger than the left lobe, while the mean length and depth of the right lobe is significantly larger in the control group than the left lobe. In addition, cut-off point values for the width of right lobe, depth of the right lobe, length of the right lobe, volume of the right lobe, width of the left lobe, depth of the left lobe, length of the left lobe, volume of the left lobe, total volume and isthmus volume were 16.5,15.5, 47.5, 6.45, 15.5, 14.5, 44.5, 5.55, 11.15, and 2.45, respectively based on the best sensitivity and specificity of the receiver operating characteristic (ROC) curve. According to logistic regression, the three factors of width of the right lobe, depth of the right lobe, and length of the right lobe, respectively, were selected as the most important ultrasound parameters in detection of thyromegaly. Thyroid volume was not significantly related with sex, age, and height, but it was directly and significantly related with weight and BMI. Conclusions: Considering the increasing use of ultrasound in detection of thyroid disease and its acceptable accuracy in determining the thyroid volume, the radiologists need to first know the normal thyroid volume and the effect of physiological variables (such as age, sex, body weight, and BMI) on the thyroid volume in their community so that they can distinguish pathological cases from normal ones. Also, the three factors of width of the right lobe, depth of the right lobe, and length of the right lobe, respectively, were determined as the most important factors in detection of thyromegaly. Thyroid volume was not significantly related with sex, age, and height, but it was directly and significantly related with weight and BMI.