Application of 3D MR Neurogram for Intraparotid Facial Nerves Evaluation

Application of 3D Magnetic Resonance Neurogram Sequences for Evaluation of Intraparotid Facial Nerves in Patients With Parotid Neoplasm

Parotid neoplasm consists of a wide range of benign and malignant lesions, and parotidectomy has been the mainstay for management of these neoplasms. Within the parotid gland there are branches of the intra-parotid facial nerves, which are tiny in calibre and are prone to injury to injury during operation. It has been reported in recent retrospective view that the incidence of temporary and permanent facial nerve injury were 9.2% and 5.2% respectively, the risk of which increased with old age, malignant tumour and revision surgery. Traditional the incidental of facial nerve injury is reduced by intra-operative facial nerve monitoring and surgical magnification, while imaging has limited role in aiding this purpose. However with advancement in MRI technique high resolution three-dimensional sequences (i.e. neurogram sequences) are available for better visualization of branches of facial nerves. The investigators would therefore aim to demonstrate additional efficacy of these techniques and also to compare with conventional 3D post-contrast anatomical imaging studies in the localization and visualization of the facial nerve branches in patients with tumour. With better pre-operative imaging, the investigators hope to reduce the chance of facial nerve injury in these patients.

Magnetic Resonance Imaging on 3T scanner (Magnetom Prisma, SIemens) with dedicated neurogram sequences (Constructive interference in steady state - CISS; Dual Echo Steady State - DESS)

The MRI examination will consist of both conventional sequences for diagnosis of salivary gland neoplasms (including DWI and DCE-MRI), together with additional neurogram sequences. (please refer to attached protocol for list of sequences)

The degree which facial nerve and branches will be visualized, by a three-point scale to each facial nerve branch, after review by radiologist. Total score of facial nerve visualization will be calculated, per MRI sequence per patient.

The sensitivity, specificity and accuracy of MRI on distinguishing benign and malignant parotid tumours using DWI and DCE-MRI.

Inclusion Criteria: Consecutive patients with parotid tumour diagnosed on other imaging modalities (such as ultrasonography or computed tomography), with or without cytological diagnosis from fine needle aspiration, will be recruited from the ear, nose and throat specialty clinic. Exclusion Criteria: Patients who are contraindicated to magnetic resonance imaging (such as due to underlying MRI incompatible metallic implants) Patient who are contraindicated to MRI contrast agents (such as advanced renal failure or previous severe allergic reaction) Patients who cannot cooperate for MRI scanning. Patients show are unable to provide informed consent.

Data to be shared includes individual participant data that underlie the results reported in this article, after deidentification.

Proposals should be directed to lhs655@ha.org.hk. To gain access, data requestors will need to sign a data access agreement. Data are available for 3 years at CUHK research data repository. (https://researchdata.cuhk.edu.hk//)