US, CT and MR imaging of parotid gland tumours

Transcription

1 US, CT and MR imaging of parotid gland tumours Poster No.: C-1509 Congress: ECR 2017 Type: Educational Exhibit Authors: T. Kamoun, A. Berriche, B. Miladi, A. merdessi, N. Mama, N Arifa, A. Ben Abdallah, H. Jemni ; Soussa/TN, SOUSSE/TN, 3 4 Nabeul/TN, Sousse, Tunisia/TN Keywords: Ear / Nose / Throat, MR-Diffusion/Perfusion, CT, UltrasoundColour Doppler, Imaging sequences, Pathology DOI: /ecr2017/C-1509 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 23

2 Learning objectives Know the different imaging modalities for the assessment of intra-parotid gland masses. Review malignant and benign parotid tumors with correlation of imaging findings with histopathology. Background The parotid space contains the parotid gland (which is the largest salivary gland), the facial nerve, the retromandibular vein, the external carotid artery and intra parotid lymph nodes. Subdivision of the parotid gland into deep and superficial lobes is made by the facial nerve and its branches (surgical approach). The facial nerve cannot be visualized by imaging: the anatomical landmark that can be used as a marker for the facial nerve is a virtual line drawn from the lateral border of retromandibular vein to the lateral edge of the mandible. Parotid tumors are uncommon neoplasms : 80%-85% of all parotid neoplasms are benign and 15%-20% are malignant. It is not always possible to clinically differentiate between intraparotid and extraparotid tumors, nor is it possible to correctly predict the malignant or benign nature of a tumor. Therefore, imaging techniques may have a place in the diagnostic work-up of patients with parotid mass lesions. Images for this section: Page 2 of 23

3 Page 3 of 23

4 Fig. 1: The anatomical landmark that can be used as a marker for the facial nerve is a virtual line drawn from the lateral border of retromandibular vein to the lateral edge of the mandible. Page 4 of 23

5 Findings and procedure details Imaging modalities: Ultrasounds: -The first step in children and pregnant women. -For lesions in the superficial lobe of the parotid gland. -To distinguish focal from diffuse disease. -To distinguish solid from cystic lesions and assess adjacent vascular structures and vascularity. -To guide fine-needle aspiration biopsy. -To perform nodal staging. Computed tomography (CT) imaging: -Indications: * If there is a suspicion of inflammatory disease: acute inflammation, abscess, calculi, major salivary duct dilatation. * In patients with contraindication for MR imaging. -Technique: *Pre-contrast study: in order to detect calcifications. *Post-contrast study (Dual phase contrast technique) : to achieve contrast enhancement of the solid tumors and lymph nodal involvement. Magnetic Resonance Imaging (MRI): -The modality of choice in evaluation of the parotid neoplasms. -Superior contrast resolution allowing a better tissue characterization (which has been further improved with the utilization of dynamic contrast enhanced MRI (DCE-MRI), diffusion-weighted MRI (DW-MRI) and apparent diffusion coefficients (ADC) values) -Ability to demonstrate the local dissemination of malignant tumors (especially the perineural dissemination which is critical in prognosis, determination of operative technique and outcome). Page 5 of 23

6 -Axial T1 and T2 weighted sequences: tissue characterization/ localization/ uni or multifocality/ tumor margins/ local extension. -Dynamic contrast enhanced MR imaging (DCE-MRI): improves the performance in differentiating benign from malignant parotid gland tumors with high value in the characterization of the different histological types (pleomorphic adenoma, Warthin's tumor and malignant tumors). Four types of time-intensity curve (TIC) described by Yabuuchi and al. with two main parameters: the time to peak enhancement and the washout ratio. Type A: Peak of enhancement (>120s) with gradual enhancement: suggesting benignancy (pleomorphic adenoma) Type B: Early peak of enhancement (#120s) with a high washout ratio (#30%) Type C: Early peak of enhancement (#120s) with a low washout ratio (<30%) Type D: flat (benign lesions such as cysts) *Type A TIC pattern is seen almost exclusively in benign pleomorphic adenoma. *Type D curves are considered benign. *In type B curves to differentiate between benign and malignant, the appropriate cut-3 2 off value is 1. Lesions with values of 1x10 mm /sec or more are considered malignant lesions. *In the type C curves the cutoff would be 1,4x mm /sec. Lesions with values of 2 1,4x10 mm /sec or more are considered benign. -Diffusion-weighted (DW-WI) sequence in the transverse plan (b values of 0 and 1000 s/mm2) with measure of apparent diffusion coefficient (ADC) value: the ADC value is essentially related to the cellularity and doesn't reflect directly a potential malignancy or benignancy of a tumor. Usually, the mean ADC value of carcinomas is significantly smaller than that of benign solid tumors; however the ADC value of Whartin's tumor is even smaller than that of malignant tumors. For malignant tumors, the ADC is significantly smaller in lymphomas than in carcinomas. Yabuuchi and al showed that the combining of the assessment of DCE- MR imaging and ADC values increases significantly the differentiation between benign and malignant parotid tumors. - T1-weighted sequences in the axial and coronal plane after gadolinium administration and with fat suppression: evaluate perineural spread along the cranial nerves (VII: stylomastoid foramen, V3: foramen ovale, V2: foramen rotundum), tumor margins and locoregional invasion. Page 6 of 23

7 Typical imaging features of the most common parotid tumors: I /Benign Tumors 1- Pleomorphic adenomas: The commonest parotid tumor by far. Middle aged females. A prior head and neck irradiation is a risk factor for the development of this tumor. Palpable slow growing mass. Superficial lobe (90%) > deep lobe (10%) Dystrophic calcification may be present in large pleomorphic adenomas (The presence of calcification suggests pleomorphic adenoma as it is rarely seen in the other parotid tumors) Variable rate of recurrence 1-50% Malignant degeneration 2-25% Appear encapsulated and well circumscribed Associated malignancies: carcinoma ex-pleomorphic Adenoma, malignant mixed tumor and metastasizing mixed tumor Must be excised completely US: hypoechoic, well-defined, lobulated tumor with posterior acoustic enhancement and possible calcifications. Vascularization in pleomorphic adenomas is often poor or absent (even when the sensitive power Doppler mode is used) but may be abundant. CT: well defined margins with high, delayed and homogeneous enhancement following the administration of contrast. Calcifications are well demonstrated on CT. MRI: well circumscribed mass with well defined and lobulated margins. They are homogeneous when they are small, whereas larger and growing tumors may be heterogeneous. -T1WI: low signal intensity -T2WI: very high signal intensity (myxoid areas) within a hypointense capsule. -It usually demonstrates a homogeneous enhancement after intraveinous injection of Gadoilinum. -DCE imaging shows usually a moderate and graduate enhancement (curve type A) Page 7 of 23

8 -DW sequence and ADC map show a high-signal-intensity mass with an ADC value usually > #3 mm2/sec. 2-Warthin's Tumour (Cystadenolymphoma): The second most common benign epithelial parotid gland tumors The most common bilateral or multifocal benign parotid tumor. Commonly in older male smokers (50-60 years old). Commonly within parotid tail, in the superficial lobe. Malignant degeneration <1% No calcification Heterogeneous appearance with partly cystic, partly solid components. US: oval, hypoechoic, well-defined tumor that often contain multiple anechoic areas. Warthin's tumor is often hypervascularized, but may also contain only short vessel segments. CT: smoothly bordered heterogeneous lesions due to cystic components. MRI: -Low to intermediate signal on T1 WI (with cyst containing cholesterol components: focal high signal on T1 WI) and heterogeneous and variable signal intensity T2 WI. -Enhancement after contrast medium administration is often relatively poor -DCE imaging shows usually an early peak of enhancement (#120s) and a high washout ratio (#30%) realizing a curve type B -The ADC value of Whartin's tumors is even smaller than that of malignant tumors (< #3 mm2/sec). 3-Hemangiomas: The most frequent tumors in infants. They may manifest as heterogeneous lesions with sinusoidal spaces and calcifications representing phleboliths. US: a homogeneous, mildly lobulated mass with fine echogenic septa, and extremely high vascularization at color Doppler imaging. Page 8 of 23

9 CT: shows the calcifications (phleboliths) MRI: high signal intensity on T2 weighted images with an important enhancement after injection of Gadolinium. 4-Lipomas: US: oval and hypoechoic mass with sharp margins and hyperechoic linear structures regularly distributed within the lesion. CT: low density (< 50 HU) MRI: iso-intense to fat on all pulse sequences on MR imaging (signal suppression on FAT SAT sequences) II/ Malignant tumors: The most common malignant neoplasms occurring mucoepidermoid carcinoma and adenoid cystic carcinoma in salivary glands are 1- Mucoepidermoid carcinoma: The most common primary parotid gland malignancy. Middle aged population (30-50 years old) Superficial >> deep Categorized into low and high grade lesions: Low-grade lesions are well circumscribed, whereas high-grade lesions tend to have ill-defined margins and infiltrate surrounding tissues. Local extension with perineural tumor spread along facial nerve. Metastasize to lymph nodes, bone and lung. US features of poorly differentiated mucoepidermoid carcinoma: an irregular shape, irregular borders, blurred margins, and a hypoechoic inhomogeneous structure. MRI: low to intermediate signal intensity can be observed on both T1- and T2-weighted images Page 9 of 23

10 Low ADC values (< #3 mm2/sec). DCE imaging shows usually an early peak of enhancement (#120s) with a low washout ratio (<30%) realizing a curve type C 2-Adenoid cystic carcinoma: The second most common parotid malignancy Typically present as an infiltrating, slow growing mass Middle aged and elderly population Perineural spread +++ Poor prognosis due to risk of perineural and perivascular invasion as well as a high rate of recurrence. Images for this section: Fig. 2: Types of Time-Intensity Curves (TIC) described by Yabuuchi and al. Page 10 of 23

11 Fig. 3: Differentiation between benign and malignant parotid tumors by combining DCEMR imaging and ADC values. Yabuuchi and al. Page 11 of 23

12 Fig. 4: Pleomorphic adenoma: Hypoechoic, well-defined, lobulated tumor with posterior acoustic enhancement and poor vascularization Dr. T.S.A. Geertsma, Ziekenhuis Gelderse Vallei, Ede, The Netherlands. Page 12 of 23

13 Fig. 5: Pleomorphic adenoma Page 13 of 23

14 Fig. 6: Pleomorphic adenoma Page 14 of 23

15 Fig. 7: Warthin's tumor: oval, hypoechoic, well-defined hyervascularized tumor. Dr. T.S.A. Geertsma, Ziekenhuis Gelderse Vallei, Ede, The Netherlands. Page 15 of 23

16 Fig. 8: Warthin's tumor Page 16 of 23

17 Fig. 9: Bilateral and multifocal parotid tumors: Warthin's tumor Page 17 of 23

18 Fig. 10: Hemangioma Fig. 11: Hemangioma Page 18 of 23

19 Fig. 12: Lipoma Page 19 of 23

20 Fig. 13: Mucoepidermoid carcinoma Page 20 of 23

21 Fig. 14: Carcinosarcoma Page 21 of 23

22 Conclusion Normal 0 21 false false false FR X-NONE AR-SA US, CT and MRI provide vital information for treatment planning and local extention of the tumor, especially the perineural spread along facial nerve. The analysis of new MR techniques combined to the other morphologic MRI criteria and clinical features offers a reliable differentiation between benign and malignant parotid tumors and a good approach of the different tumor entities. Personal information References Thoeny, H. C. (2007). Imaging of salivary gland tumours. Cancer Imaging, 7(1), 52. Keh, S. M., Tait, A., & Ahsan, F. (2011). Primary carcinosarcoma of the parotid gland. Clinics and practice, 1(4). Yabuuchi H, Fukuya T, Tajima T, Hachitanda Y, Tomita K, Koga M. Salivary gland tumors: diagnostica value of gadolinium-enhanced dynamic MR imaging with histopathologic correlation. Radiology Feb;226(2): Erratum in: Radiology Jun;227(3):909. Yabuuchi H, Matsuo Y, Kamitani T, Setoguchi T, Okafuji T, Soeda H, et al. Parotid gland tumors: can addition of diffusion-weighted MR imaging to dynamic contrast-enhanced imaging improve diagnostic accuracy in characterization? Radiology Dec;249(3): Ikeda M, Motoori K, Hanazawa T, Nagai Y, Yamamoto S, Ueda T, Funatsu H, Ito H. Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation. AJNR Am J Neuroradiol Aug;25(7): Eida S, Sumi M, Sakihama N, Takahashi H, Nakamura T. Apparent diffusion coefficient mapping of salivary gland tumors: prediction of the benignancy and malignancy. AJNR Am J Neuroradiol Jan;28(1): Eida S, Sumi M, Nakamura T. Multiparametric magnetic resonance imaging for the differentiation between benign and malignant salivary gland tumors. J MagnReson Imaging. 2010;31(3): Page 22 of 23

23 8. 9. Habermann CR, Arndt C, Graessner J, Diestel L, Petersen KU, Reitmeier F, Ussmueller JO, Adam G, Jaehne M. Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible? AJNR Am J Neuroradiol. 2009;30(3): Burke C, Thomas R, Howlett D. Imaging the major salivary glands. British Journal of Oral and Maxillofacial Surgery. 2011, Volume 49: p Page 23 of 23