Parotid gland tumors: comparison of conventional and diffusion-weighted MRI findings with histopathological results

Abstract

Objectives: The aim of this study was to investigate the relationship between pathological classification of parotid gland tumors and conventional magnetic resonance imaging (MRI) – diffusion weighted imaging (DWI) findings and also contribute the possible effect of apparent diffusion coefficient (ADC) to diagnosis. Methods: Sixty patients with parotid masses diagnosed using histopathology and/or cytology were enrolled in this retrospective study. All patients were evaluated using a 1.5 Tesla MRI. Demographic features, conventional MRI findings, and ADC values (mean, minimum, maximum, and relative) were recorded. MRI findings and ADC values were compared between benign-malignant groups and pleomorphic adenoma versus Warthin’s tumor groups. Results: Sixty tumors (48 benign, 12 malignant) were evaluated in a total of 60 patients (39 males, 21 females). The mean age was 59 (±14, 18–86) years old; the mean lesion size was 26 (±10, 11–61) mm. On the texture of conventional MRI, T2 dominantly hyperintense/with hypointensity signal was seen in 87% of pleomorphic adenomas and T2 dominantly hypointense/with hyperintesity signal was encountered in 64% of all Warthin’s tumors. Seven (28%) Warthin’s tumors were misdiagnosed as pleomorphic adenomas and two others (8%) as malignant tumors. The commonly used mean ADC value was 1.6 ± 0.6 × 10–3 mm2 sec−1 for benign tumors, 0.8 ± 0.3 × 10–3 mm2 sec−1 for malign tumors, 1 (0.9–1.8) × 10–3 mm2 sec−1 for Warthin’s tumors, and 1.9 ± 0.3 × 10–3 mm2 sec−1 for pleomorphic adenomas. There was a statistically significant difference in ADC values between benign-malignant tumors and pleomorphic adenomas-Warthin’s tumors. Conclusions: Warthin’s tumor may occasionally be misdiagnosed as pleomorphic adenoma and malignant tumor because of variable morphologic features. In addition to benign-malignant differentiation, the added ADC measurement may also be useful for differentiating Warthin’s tumors from pleomorphic adenomas.

Differentiation of Benign From Malignant Parotid Gland Tumors Using Conventional MRI Based on Radiomics Nomogram

“…This may be because PA is rich in myxoid and chondroid tissue stroma and has a larger extracellular space than WT, causing a considerable difference in heterogeneity in the ADC model (37,38). This also verifies the application of ADC values in the quantitative analysis to some extent to differentiate PA from WT (39). FS-T2WI or CE-T1WI combined with ADC can improve the performance of the single-sequence model, consistent with previous studies (17,40,41).…”

Differentiation of Benign and Malignant Parotid Gland Tumors with MRI and Diffusion Weighted Imaging

“…In previous DWI studies, significant differences in ADC values were reported between benign and malignant head and neck tumors, including salivary gland tumors 18 . Also, it was reported that T2 SI is lower in Whartin tumors and malignant parotid tumors 8 . The morphological features of PGTs can be evaluated by MRI, but detecting the lesions and defining the features may not be sufficient to avoid a biopsy.…”

“…We could not find any significant association between malignant and benign lesions in terms of deep or superficial lobe localization. It was previously reported that the tumor heterogeneity and T2 hypointensity may indicate malignancy, and it is not sufficient for precise differentiation 8 . Our results revealed that the T2 SI of the Warthin tumors was significantly lower than that of the pleomorphic adenomas.…”

“…At that point, Magnetic Resonance Imaging (MRI) can play an important role in providing information about the location, and extension of the lesion, presence of perineural spread, nodal and distant metastases 4 . The advances in diffusion weighted imaging (DWI) play important roles in distinguishing benign and malignant tumors by providing information on the microcirculation and microcellularity of the tumors 8 . To this respect, we hypothesized that signal intensity (SI) and Apparent Diffusion Coefficient (ADC) values can be used to differentiate malignant and benign parotid gland tumors based of differences in cellularity.…”

The Diagnostic Value of Ultrasound-Based Deep Learning in Differentiating Parotid Gland Tumors

“…Classification of PGTs is hampered by the diverse variations in their histopathology. Presurgical determination of benign or malignant PGTs involves two main methods: fine needle aspiration cytology (FNAC) [ 4 ] and imaging modalities [ 5 ]. Although preoperative FNAC examination can improve the diagnostic accuracy, its use in the diagnosis of PGT is controversial.…”