Ultrasound Versus CT: A Comparative Accuracy Study in the Assessment of Thyroid Cartilage Infiltration in Laryngeal–Hypopharyngeal Carcinoma

Abstract

Background:

Accurate preoperative assessment of thyroid cartilage invasion (TCI) is crucial for staging and surgical decision-making in laryngeal and hypopharyngeal carcinoma. Although contrast-enhanced computed tomography (CT) is routinely employed, high-resolution ultrasonography (US) offers a radiation-free, real-time, and cost-effective alternative for evaluating cartilage integrity.

Objective:

To compare the diagnostic performance of high-resolution ultrasonography and contrast-enhanced CT in detecting TCI, using histopathological examination (HPE) as the reference standard.

Methods:

A prospective comparative study was conducted on 45 biopsy-proven cases of laryngeal and hypopharyngeal carcinoma between 2022 and 2024 at Vydehi Institute of Medical Sciences, Bengaluru. Each patient underwent transcutaneous high-resolution US followed by multidetector contrast-enhanced CT of the neck. Imaging findings were categorized as no, minor, or major invasion based on cortical continuity and soft-tissue extension. HPE served as the reference standard. Diagnostic indices—sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy—were calculated, and correlation between modalities was analyzed using the Pearson chi-square (χ²) test.

Results:

Of the 45 patients, 39 (86.7%) were men and 6 (13.3%) women, predominantly aged 51–70 years. The pyriform sinus (33.3%) and vocal cords (24.4%) were the most common primary sites. US detected cartilage erosion in 20 (44.4%) cases, CT in 28 (62.2%), and HPE confirmed invasion in 25 (55.6%). A statistically significant association existed between the two imaging modalities (χ² = 21.857; p < 0.001). Compared with histopathology, US achieved sensitivity 88%, specificity 79%, PPV 97%, NPV 65%, and accuracy 96%; CT achieved sensitivity 78%, specificity 70%, PPV 94%, NPV 72%, and accuracy 80%.

Conclusion:

High-resolution ultrasonography demonstrates excellent diagnostic accuracy and sensitivity for detecting thyroid cartilage invasion and shows strong concordance with histopathological findings. While CT remains indispensable for comprehensive staging and evaluation of deep or extralaryngeal spread, ultrasonography serves as a reliable, radiation-free, and cost-efficient complementary tool—particularly valuable in resource-limited settings.