Diffusion-weighted MRI for differentiation between sialadenitis and pleomorphic adenoma

Aim The aim of this study was to investigate the diffusion‐weighted magnetic resonance imaging (DWI) in the palatal tumors, especially usefulness of apparent diffusion coefficient (ADC) value for characterization of benign and malignant tumors. Materials and Methods Twenty‐four patients with palatal tumors (16 malignant tumors and 8 benign tumors) who underwent DWI for diagnosis of palatal lesions were included in this prospective study. DWI was performed on a 1.5 T unit, with b factor of 0 and 800 s/mm2; moreover, ADC maps were generated. ADC values were measured for the palatal tumors. The histopathological diagnoses were obtained by surgery in all cases. The ADC values of the palatal tumors were evaluated by one‐way repeated‐measures analysis of variance with Tukey's HSD test. A P value lower than .05 was considered as statistically significant. Results The mean ADC value of squamous cell carcinoma (1.10 ± 0.11 × 10−3 mm2 s−1) was significantly lower than that of pleomorphic adenoma (1.49 ± 0.41 × 10−3 mm2 s−1, P = .046) and another benign tumor (1.85 ± 0.40 × 10−3 mm2 s−1, P = .000). Conclusions ADC value derived from DWI could be useful for the characterization of benign and malignant palatal tumors.

Objectives: To provide basic information on the magnetic resonance imaging modalities, emphasizing the diffusion-weighted imaging technique, as well as to clarify its applicability to diagnose major salivary gland disorders. Methods: The PRISMA statement was used during data assessment and extraction. The MEDLINE (PubMed) database was searched for the period from 2010 to November 2017, for studies providing basic information on the MRI modalities as well its applicability to diagnose salivary gland disorders. Data extraction included information regarding: application of MRI modalities especially ADC and DWI to diagnose major salivary gland disorders. Results: The search yielded 58 publications in MEDLINE (PubMed). The initial screening of the publications was performed using abstracts and keywords. After application of exclusion criteria, we identified a total of 9 studies as eligible to be discussed. Studies revealed two main types of MRI modalities: ADC and DWI. Most of the studies suggest that MRI can be useful as a diagnostic tool for major salivary glands. Conclusion: MRI modalities are advantageous tools for salivary gland tissue evaluations. To demonstrate the accuracy of the distinct approach methods and modalities, more studies involving a larger number of patients studied are necessary.

| Salivary glands tumors account for 2-5% of tumors in the head and neck region, possibly being benign or malignant.Magnetic resonance imaging (MRI) presents high soft tissue contrast resolution, thus being an excellent method for salivary gland analysis. The objective of this literature review is to analyze MRI as an evaluation instrument for the diagnosis of salivary glands lesions. Compared to other imaging techniques, MRI can better evaluate the relationship between adjacent anatomical structures, presenting greater sensitivity and specificity. DESCRIPTORS | Magnetic Resonance Imaging; Salivary Glands; Diagnosis.RESUMO | Imagem por ressonância magnética das glândulas salivares: uma revisão da literatura • Os tumores das glândulas salivares são responsáveis por 2-5 % dos tumores da região da cabeça e pescoço, podendo ser benignos ou malignos. A Ressonância Magnética (RM) possui uma alta resolução de contraste dos tecidos moles, sendo assim um excelente método para a análise das glândulas salivares. O objetivo dessa revisão de literatura consiste na análise da RM para a avaliação no diagnóstico de lesões das glândulas salivares. Comparando com outras técnicas de imagem, a RM consegue avaliar melhor a relação entre estruturas anatômicas adjacentes e possui maior sensibilidade e especificidade. DESCRITORES |