The usefulness of MR in establishing the diagnosis of parotid pleomorphic adenoma
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K Ikeda1, T Katoh, S K Ha-Kawa
1Department of Radiology, Kansai Medical University, Osaka, Japan.
Purpose:
To assess the usefulness of MR findings in establishing a specific diagnosis of parotid pleomorphic adenoma.
Methods:
T1-weighted and T2-weighted MR images with and without contrast enhancement were obtained in 82 patients with parotid tumors. Imaging findings in the 38 patients in whom surgery subsequently revealed pleomorphic adenomas were compared with findings in the 44 patients who had other types of tumor. Specifically, the homogeneity, signal intensity, contrast enhancement, capsule thickness, lobulation, adenopathy, and infiltration of adjacent fat were compared among the different types of tumor. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated.
Results:
A low-signal capsule on T2-weighted images and a lobulated contour characterized most pleomorphic adenomas. The sensitivity of the first finding for pleomorphic adenoma was 82%; specificity, 85%; positive predictive value, 82%; and negative predictive value, 84%. For the second finding, the sensitivity was 53%; specificity, 84%; positive predictive value, 74%; and negative predictive value, 67%.
Conclusion:
None of the signs evaluated had perfect sensitivity and specificity. The MR findings of a complete capsule, lobulated contour, or high T2 signal intensity have a high predictive value for the diagnosis of pleomorphic adenoma.
Insights
Magnetic resonance (MR) imaging can help diagnose parotid pleomorphic adenoma. A low-signal capsule on T2-weighted images and lobulated contour are key indicators for this common salivary gland tumor.
Area of Science:
- Radiology
- Oncology
Background:
- Parotid pleomorphic adenoma is the most common benign salivary gland tumor.
- Accurate preoperative diagnosis is crucial for appropriate management.
Purpose of the Study:
- To evaluate the diagnostic utility of specific magnetic resonance (MR) imaging findings for parotid pleomorphic adenoma.
Main Methods:
- Retrospective analysis of MR images (T1/T2-weighted, with/without contrast) from 82 patients with parotid tumors.
- Comparison of imaging features between 38 confirmed pleomorphic adenomas and 44 other tumor types.
- Calculation of sensitivity, specificity, and predictive values for key MR findings.
Main Results:
- A low-signal capsule on T2-weighted images showed 82% sensitivity and 85% specificity for pleomorphic adenoma.
- A lobulated contour had 53% sensitivity and 84% specificity.
- Neither finding alone provided perfect diagnostic accuracy.
Conclusions:
- MR imaging findings, including a complete capsule, lobulated contour, and high T2 signal intensity, offer high predictive value for diagnosing parotid pleomorphic adenoma.
- While not perfect, these MR features aid in distinguishing pleomorphic adenomas from other parotid tumors.