Publication:

Diagnostic performance of ACR TI-RADS in solitary thyroid nodule: a comparative study with FNAC in a tertiary care hospital in Bangladesh

Background Thyroid nodules are highly prevalent in iodine-deficient regions in Bangladesh. The American college of radiology thyroid imaging reporting and data system (ACR TI-RADS) offers a standardized, non-invasive ultrasound-based risk stratification tool. This study evaluates its diagnostic accuracy against Fine Needle Aspiration Cytology (FNAC), the gold standard.

Methods This cross-sectional study was conducted from April 2025 to March 2026 at BIRDEM General Hospital, Dhaka. A total of 85 adult patients (≥18 years) with solitary thyroid nodule underwent high-resolution USG for ACR TI-RADS grading, followed by USG-guided FNAC (Bethesda classification). Diagnostic accuracy metrics sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and area under the curve (AUC) were calculated using FNAC as the reference standard.

Results Among 85 participants, females constituted 81.2% with a male-to-female ratio of 1:4.3. The mean age was 43.6±11.8 years. ACR TI-RADS distribution: TR2 (19.0%), TR3 (35.3%), TR4 (27.0%), TR5 (18.7%). FNAC revealed suspicious for follicular neoplasm (2.4%) and non-diagnostic (3.5%). Using TR≥4 as the cut-off for malignancy (n=82 after excluding non-diagnostic cases), ACR TI-RADS demonstrated: sensitivity 85.7%, specificity 80.88%, PPV 48.00%, NPV 96.49%, accuracy 81.71%, positive likelihood ratio (LR+) 4.48, negative likelihood ratio (LR−) 0.18 and AUC 0.862 (p<0.001).

Conclusions ACR TI-RADS exhibits excellent negative predictive value (96.49%) and a strong negative likelihood ratio (0.18), confirming its high reliability as a rule-out test for malignancy in solitary thyroid nodule. Low-risk (TR1–3) nodules can be safely managed with sonographic surveillance, while high-risk (TR4–5) nodules warrant FNAC confirmation.