Imaging of salivary gland tumours

Multiparametric magnetic resonance imaging for the differentiation between benign and malignant salivary gland tumors

PURPOSE

To evaluate the stepwise approach in differentiating between benign and malignant salivary gland tumors using time-intensity curves (TICs) and apparent diffusion coefficients (ADCs).

MATERIALS AND METHODS

TICs and ADCs were analyzed on the tumor-by-tumor (overall) and pixel-by-pixel (TIC and ADC maps) bases in patients with benign (n = 52) or malignant (n = 18) salivary gland tumor. TICs were categorized into Types 1 (<20% increment ratio), 2 (>or=20% increment ratio and >120 sec peak time), 3 (>or=20% increment ratio, <or=120 sec peak time, and <30% washout ratio), or 4 (>or=20% increment ratio, <or=120 sec peak time, and >or=30% washout ratio). ADCs were classified as extremely low (<0.6 x 10(-3) mm(2)/sec), low (<1.2), intermediate (<1.8), or high (>or=1.8).

RESULTS

Malignant tumors had small (<30%) areas with Type 1 TIC with one of the following magnetic resonance imaging (MRI) characteristics: Type 3 overall TIC patterns, Type 4 overall TIC patterns and extremely low (<0.60 x 10(-3) mm(2)/sec) overall ADCs, or Type 2 overall TIC patterns and large (>40%) areas with low or extremely low ADCs.

CONCLUSION

We propose a stepwise approach by using multiparametric MRI techniques as an effective tool for differentiating between benign and malignant salivary gland tumors.

Magnetic resonance imaging with pathological correlation in a case of mantle cell lymphoma of the parotid gland: a case report

Introduction

Mantle cell lymphoma is a rare non-Hodgkin's lymphoma. It is a subtype of B-cell lymphoma with frequent involvement of the bone marrow and the gastrointestinal tract. Isolated parotid gland involvement seldom occurs. Here we report an unusual case of isolated infiltration of the parotid gland by mantle cell lymphoma. The aim of our study is to correlate magnetic resonance imaging findings with the histological features of the disease. To the best of our knowledge, no similar radiological findings of mantle cell lymphoma have been published before.

Case presentation

A 72-year-old Caucasian woman presented with a painful left parotid enlargement. She was diagnosed with mantle cell lymphoma involving the left submandibular gland seven years prior to presentation. Her whole body CT scan showed the absence of pathologically enlarged lymph nodes. However, a magnetic resonance imaging showed enlargement of her left parotid gland and an abnormal parenchyma with mixed-type solid and cystic lesions. A biopsy of her left parotid gland and subsequent histological examination confirmed a mantle cell lymphoma (common variant) relapse.

Conclusion

Although rare, the involvement of parotid gland with mantle cell lymphoma must be considered in the differential diagnosis of parotid tumors.

Giant epithelial-myoepithelial carcinoma of the parotid gland

We present the case of an elderly woman with a painless giant tumor of the neck. Computed tomography (CT) demonstrated a cyst-like lesion that appeared to arise from the parotid gland. The tumor was removed in toto and histopathologically diagnosed as an epithelial-myoepithelial carcinoma. Such rare carcinomas should be considered in the differential diagnosis of parotid gland malignancies. We discuss the possibilities of imaging modalities such as CT and magnetic resonance imaging (MRI) in the differentiation between benign and malignant salivary gland tumors.

Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible?

BACKGROUND AND PURPOSE

Our aim was to determine the value of echo-planar diffusion-weighted MR imaging (epiDWI) in differentiating various types of primary parotid gland tumors.

MATERIALS AND METHODS

One hundred forty-nine consecutive patients with suspected tumors of the parotid gland were examined with an epiDWI sequence by using a 1.5T unit. Image analysis was performed by 2 radiologists independently, and the intraclass correlation coefficient was computed. Histologic diagnosis was obtained in every patient. For comparison of apparent diffusion coefficients (ADCs), a paired 2-tailed Student t test with a Bonferroni correction was used.

RESULTS

In 136 patients, a primary parotid gland tumor was confirmed by histology. Among the observers, a high correlation was calculated (0.98). ADC values of pleomorphic adenomas were significantly higher than those of all other entities, except for myoepithelial adenomas (P = .054). ADC values of Warthin tumors were different from those of myoepithelial adenomas, lipomas, and salivary duct carcinomas (P < .001, 0.013, and .037, respectively). Mucoepidermoid carcinomas, acinic cell carcinomas, and basal cell adenocarcinomas were not differentiable from Warthin tumors (P = .094, .396, and .604, respectively).

CONCLUSION

epiDWI has the potential to differentiate pleomorphic adenoma and myoepithelial adenomas from all other examined entities. Due to an overlap not only within the group of benign and malignant lesions but also between groups, diagnoses should not be addressed on the basis of ADC values solely. Therefore, further studies combining DWI, morphologic criteria, and probably other MR imaging techniques seem warranted.

Diffusion-weighted MRI in head and neck cancer

Diffusion-weighted magnetic resonance imaging (MRI) is an imaging technique showing molecular diffusion. Cell size, density and integrity influence the signal intensity seen on diffusion-weighted images. This technique is a helpful complementary tool to distinguish tumoral from non-tumoral tissue, and has several interesting applications in the evaluation of head and neck cancer.