Morphological Evaluation of the Thyroid Lobes and Isthmus in Asymptomatic Indian Young Adults using Ultrasonography: A Cross-sectional Study

Introduction: Studies on morphological variations of the thyroid gland have been published from various parts of the world. Awareness of these variations becomes critical for diagnosing pathologies involving the gland and for surgeons dealing with head and neck surgery. Aim: To observe and document asymmetry in thyroid morphology using ultrasonography (visual inspection followed by size estimation) in asymptomatic subjects. Materials and Methods: It was a descriptive cross-sectional study, which included 100 volunteer first year students (50 males and 50 females), who attended classes from April 2019-March 2020 in the Department of Anatomy, King George’s Medical University, Lucknow, Uttar Pradesh, India. Ultrasonography of the thyroid gland was performed and the image showing the thyroid isthmus along with both the lobes at their greatest depth and width was captured. The thickness of isthmus was also observed at this stage. Any visual asymmetry observed was noted; thereafter, in these subjects displaying asymmetry on close examination, the maximal width (mediolateral), maximal depth (anteroposterior), and greatest length (craniocaudal) of each lobe was taken. The statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 24. The values were represented in number (%) and mean±Standard Deviation (SD). Results: During sonographic assessment of the thyroid gland, visual asymmetry was observed on the coronal scan images in 24 out of 100 individuals (14 females and 10 males). These 24 cases were subjected to assessment of actual size measurements on ultrasound. In 23 of these subjects (13 females, 10 males), this asymmetry on close examination was correctly validated during measurements. However, in 1 female subject, the apparent asymmetry of lobe visualised via the transverse scan, did not translate into a difference in measurements, i.e., both the lobes measured almost similar. An asymmetry in thickness of isthmus was also uniquely observed in 10 subjects (8 females and 2 males). Conclusion: Visual assessment of thyroid lobes using ultrasonographic examination revealed asymmetry in lobe size, which was congruent with the measurement of dimensions of the lobes and also asymmetric isthmus thickness was seen. Hence, ultrasonographic examination proved to be a useful tool in routine diagnosis and treatment planning procedures.