Characteristic bright signal of parotid pleomorphic adenomas on T2-weighted MR images with pathological correlation

doi:10.1016/S0009-9260(05)81748-9

Clinical Radiology

Volume 49, Issue 7, July 1994, Pages 485-489

https://doi.org/10.1016/S0009-9260(05)81748-9 Get rights and content

The purpose of this study was to correlate the MR features and histological findings of pleomorphic adenomas, which are the most common tumour of the parotid gland, and to distinguish them from other types of tumour in the parotid gland. The materials studied consisted of 20 pleomorphic adenomas, including 12 untreated and eight recurrent cases, 17 other benign parotid tumours, and 12 malignant tumours. T1- and T2-weighted images and Gd-DTPA enhanced T1-weighted images were obtained. Characteristic bright signals with a higher intensity than that of CSF were seen in all of the pleomorphic adenomas on T2-weighted images, and were found to represent myxoid areas histologically. Although the cystic spaces in some benign tumours produced bright signals, these areas were distinguished from myxoid areas due to nonenhancement with Gd-DTPA. No bright signals were seen in the malignant tumours. In conclusion, bright signals on T2-weighted images represent myxoid tissue and are useful findings for diagnosing pleomorphic adenomas.

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Citation Excerpt :
However, having access to a relatively larger group of cases than in previous studies, we identified slightly different cut-off values for Tpeak and WR than proposed by other authors. In previous studies, the cut-off values accurately distinguishing between parotid malignancies and Warthin tumors were identified as Tpeak = 60 s or Tpeak = 120 s and WR = 30% or WR = 40%, and differential diagnostics of malignant lesions and pleomorphic adenomas was based on Tpeak = 120 s, Tpeak = 210 s or Tpeak = 240 s and WR = 10% [6,12,22,23]. Also the cut-off value for Tmax proposed by Hisatomi et al. [6] as optimally differentiating between malignant tumors and pleomorphic adenomas (Tmax = 210 s) was lower than the cut-off value for this parameter determined in our series (Tmax = 235 s).
To verify if differential diagnostic algorithms based on selected parameters of dynamic and diffusion-weighted MRI, clinical and demographic variables are accurate enough to differentiate between parotid malignancies, pleomorphic adenomas and Warthin tumors.
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Compared to Warthin tumors, parotid malignancies showed higher T_peak, T_max and ADC, lower WR, were more often located in the deep lobe of the parotid and presented as single lesions with concomitant lymphadenopathy. Consideration of all these variables provided 100% sensitivity and 89.2% specificity of the differential diagnostic algorithm. Compared to pleomorphic adenomas, parotid malignancies presented with lower ADC and T_peak, higher T_max, were more often located in the deep lobe of the parotid, associated with concomitant lymphadenopathy, diagnosed in men and individuals older than 66 years. Consideration of all these variables provided 100% sensitivity and 96.4% specificity of the differential diagnostic algorithm.
Combined analysis of clinical data and results of dynamic and diffusion-weighted MRI may provide nearly ideal accuracy in differential diagnostics of parotid malignancies and the two most common histological types of benign tumors.
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Characteristic bright signal of parotid pleomorphic adenomas on T2-weighted MR images with pathological correlation

American Journal of Surgery

Parotid masses: MR imaging

Radiology

Parotid masses: MR imaging

Radiology

High-grade malignancies of the parotid gland: identification with MR imaging

Radiology

Benign and malignant parotid pleomorphic adenomas: CT and MR studies

Journal of Computer Assisted Tomography

MR imaging of parotid mass lesions: attempts at histopathologic differentiation

Journal of Computer Assisted Tomography