Diffusion-weighted MR Imaging and ADC Mapping in Differentiating Benign from Malignant Thyroid Nodules.

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Thyroid nodules are common, with a significant proportion being malignant.
• Accurate differentiation between benign and malignant nodules is crucial for appropriate patient management.
• Fine Needle Aspiration Cytology (FNAC) and biopsy can be inconclusive or technically challenging for some nodules.

Purpose of the Study:

• To evaluate the diagnostic accuracy of Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) mapping in distinguishing benign from malignant thyroid nodules.
• To establish the utility of DWI and ADC in improving diagnostic confidence for thyroid nodules.

Main Methods:

• A cross-sectional analytical study was conducted involving 35 patients with thyroid nodules.
• MRI including DWI (b-values 0 and 1000 s/mm²) was performed to obtain ADC values.
• Histopathology results from ultrasound-guided core biopsies served as the gold standard for comparison.

Main Results:

• Malignant nodules exhibited restricted diffusion (lower mean ADC values: 0.94 ±0.16 x 10⁻³ mm²/s) compared to benign nodules (facilitated diffusion, higher mean ADC values: 1.93 ±0.13 x 10⁻³ mm²/s).
• An ADC cut-off value of 1.6 x 10⁻³ mm²/s demonstrated high diagnostic performance.
• DWI and ADC achieved a sensitivity of 93%, specificity of 95%, and overall diagnostic accuracy of 92.3%.

Conclusions:

• Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) mapping are effective non-invasive tools for characterizing thyroid nodules.
• These imaging techniques can reliably differentiate between benign and malignant thyroid lesions.
• DWI/ADC can reduce unnecessary surgeries and aid diagnosis when biopsies are inconclusive or nodules are not amenable to biopsy.