Advanced magnetic resonance imaging findings in salivary gland tumors

Abstract

Salivary gland tumors (SGTs) make up a small portion (approximately 5%) of all head and neck tumors. Most of them are located in the parotid glands, while they are less frequently located in the submandibular glands, minor salivary glands or sublingual gland. The incidence of malignant or benign tumors (BTs) in the salivary glands varies according to the salivary gland from which they originate. While most of those detected in the parotid gland tend to be benign, the incidence of malignancy increases in other glands. The use of magnetic resonance imaging (MRI) in the diagnosis of SGTs is increasing every day. While conventional sequences provide sufficient data on the presence, localization, extent and number of the tumor, they are insufficient for tumor specification. With the widespread use of advanced techniques such as diffusion-weighted imaging, semi-quantitative and quantitative perfusion MRI, studies and data have been published on the differentiation of malignant or BTs and the specificity of their subtypes. With diffusion MRI, differentiation can be made by utilizing the cellularity and microstructural properties of tumors. For example, SGTs such as high cellular Warthin’s tumor (WT) or lymphoma on diffusion MRI have been reported to have significantly lower apparent diffusion values than other tumors. Contrast agent uptake and wash-out levels of tumors can be detected with semi-quantitative perfusion MRI. For example, it is reported that almost all of the pleomorphic adenomas show an increasing enhancement time intensity curve and do not wash-out. On quantitative perfusion MRI studies using perfusion parameters such as Ktrans, Kep, and Ve, it is reported that WTs can show higher Kep and lower Ve values than other tumors. In this study, the contribution of advanced MRI to the diagnosis and differential diagnosis of SGTs will be reviewed.

Diagnostic efficacy of diffusion-weighted imaging and semiquantitative and quantitative dynamic contrast-enhanced magnetic resonance imaging in salivary gland tumors

“…High K ep and low V e values in WTs are explained by the limited extravascular and extracellular space in these tumors. As many studies in the literature and the present study revealed, ADC and TIC patterns of WTs could overlap with those of MTs[ 11 ]. However, similar to the findings of the studies in the literature, the present study showed that quantitative perfusion MRI parameters K ep and V e could contribute greatly to distinguishing WTs from MTs[ 3 , 14 , 15 ].…”

“…In recent years, an increase has been reported in diagnostic accuracy in SGTs for distinguishing between MTs and BTs with the use of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI techniques[ 1 , 5 - 9 ]. DCE MRI is used to track an exogenous, paramagnetic contrast agent in tissues and has been a powerful tool in the characterization of tumor hemodynamics[ 1 , 3 , 10 , 11 ]. As a semiquantitative method in DCE MRI, patterns have been established by measuring time to peak (T peak ) and washout ratio (WR) on the time intensity curve (TIC)[ 1 , 3 ].…”

Radiomics Analysis in Characterization of Salivary Gland Tumors on MRI: A Systematic Review

“…The MRI protocol for SGTs typically includes multiple MRI sequences, such as T1WI, T2WI, and CE images. Functional MRI techniques, such as dynamic contrast-enhanced (DCE) MRI and DWI, have also demonstrated potential for characterizing SGTs and are increasingly included in the MRI protocol for SGTs [33]. In radiomics analysis, it is not surprising that our results showed that models constructed using multiple MRI sequences outperformed those built using a single sequence.…”

Minor Salivary Gland Polymorphous Adenocarcinoma With Local Recurrence After Seven Years: A Case Report

“…Furthermore, CT provides information on bone invasion by the lesion [ 3 , 11 , 12 ]. On MRI, the lesions may appear as an intermediate signal on T1 and hyperintense on T2 [ 13 ], with low values (0.95 ± 0.09) on the apparent diffusion coefficient map [ 14 ]. MRI also provides information about perineural lesion invasion [ 15 ].…”