Diagnostic Performance of Ultrasound Thyroid Imaging Reporting & Data System and Thyroid Scintigraphy for Detection of Malignancy in Patients with Solitary Thyroid Nodule

Abstract

Background: Solitary thyroid nodules are common in general population; most being asymptomatic and detected only through imaging. The main clinical concern is their potential risk of malignancy because thyroid cancer incidence had significantly increased over recent decades. Ultrasonography, the preferred imaging modality provides detailed structural information. In contrast, thyroid scintigraphy categorizes nodules based on functional status. The American College of Radiology has proposed the ultrasound Thyroid Imaging Reporting and Data System (TIRADS) that enhances ultrasound’s ability to stratify malignancy risk, offering a structured approach to management decisions in solitary thyroid nodules.

Objective: To compare diagnostic performance of ultrasound TIRADS and thyroid scintigraphy for detection of malignancy in patients with solitary thyroid nodule.

Methods: This cross-sectional study was carried out in the Department of Radiology and Imaging at Dhaka Medical College Hospital and the Institute of Nuclear Medicine and Allied Sciences, Dhaka, from March 2023 to February 2025. A total of 74 adult patients with solitary thyroid nodule were included in this study by non probability sampling. In all patients both ultrasound TIRADS and thyroid scintigraphy were done to evaluate the characteristics of the nodule. Patients were operated for nodule and postoperative biopsy was done for histopathology in each patient. Results of both ultrasound TIRADS and thyroid scintigraphic findings were compared with that of histopathology as gold standard to determine their (TIRADS & scintigraphy) diagnostic performance for malignancy detection with respect to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

Results: The mean age of the participants was 43.5 ± 11.0 years, with a higher frequency of females (64.9%). Ultrasound TIRADS classified, 36.5% of nodules as malignant (TIRADS 4-5). Thyroid scintigraphy showed 81.1% of nodules as cold (malignant). Histopathological analysis confirmed 20.3% of nodules as malignant. TIRADS demonstrated higher sensitivity (93.3%), specificity (77.97%), PPV (51.85%), NPV (97.87%) and accuracy (81.08%) in detecting malignancy compared to thyroid scintigraphy (sensitivity 66.67%, specificity 15.25%, PPV 16.67%, NPV 64.29% and accuracy 25.68%).

Conclusion: This study demonstrates that ultrasound TIRADS is a more reliable imaging modality than thyroid scintigraphy for detection of malignancy in solitary thyroid nodules with significantly higher sensitivity, specificity, PPV, NPV and accuracy. While thyroid scintigraphy remains useful for functional assessment. Its limited specificity (15.25%) makes it ineffective for malignancy detection.

Bangladesh Medical Res Counc Bull 2025;51(1):46-52