The location of parotid gland tumors in relation to the facial nerve on magnetic resonance images and computed tomography scans

MR-Neurography of the facial nerve in parotid tumors: intra-parotid nerve visualization and surgical correlation

PURPOSE

One of the most severe complications in surgery of parotid tumors is facial palsy. Imaging of the intra-parotid facial nerve is challenging due to small dimensions. Our aim was to assess, in patients with parotid tumors, the ability of high-resolution 3D double-echo steady-state sequence with water excitation (DE3D-WE) (1) to visualize the extracranial facial nerve and its tracts, (2) to evaluate their relationship to the parotid lesion and (3) to compare MRI and surgical findings.

METHODS

A retrospective study was conducted including all patients with parotid tumors, who underwent MRI from April 2022 to December 2023. Two radiologists independently reviewed DE3D-WE images, assessing quality of visualization of the facial nerve bilaterally and localizing the nerve's divisions in relation to the tumor. MRI data were compared with surgical findings.

RESULTS

Forty consecutive patients were included (M:F = 22:18; mean age 56.3 ± 17.4 years). DE3D-WE could excellently visualize the nerve main trunk and the temporofacial division in all cases. The cervicofacial branch was visible in 99% of cases and visibility was good. Distal divisions were displayed in 34% of cases with a higher visibility on the tumor side (p < 0.05). Interrater agreement was high (weighted kappa 0.94 ± 0.01 [95% CI 0.92-0.97]). Compared to surgery accuracy of MRI in localizing the nerve was 100% for the main trunk, 96% for the temporofacial and 89% for the cervicofacial branches.

CONCLUSIONS

Facial nerve MR-neurography represents a reliable tool. DE3D-WE can play an important role in surgical planning of patients with parotid tumors, reducing the risk of nerve injury.

Direct visualization of intraparotid facial nerve assisting in parotid tumor resection

Precise recognition of the intraparotid facial nerve (IFN) is crucial during parotid tumor resection. We aimed to explore the application effect of direct visualization of the IFN in parotid tumor resection. Fifteen patients with parotid tumors were enrolled in this study and underwent specific radiological scanning in which the IFNs were displayed as high-intensity images. After image segmentation, IFN could be preoperatively directly visualized. Mixed reality combined with surgical navigation were applied to intraoperatively directly visualize the segmentation results as real-time three-dimensional holograms, guiding the surgeons in IFN dissection and tumor resection. Radiological visibility of the IFN, accuracy of image segmentation and postoperative facial nerve function were analyzed. The trunks of IFN were directly visible in radiological images for all patients. Of 37 landmark points on the IFN, 36 were accurately segmented. Four patients were classified as House-Brackmann Grade I postoperatively. Two patients with malignancies had postoperative long-standing facial paralysis. Direct visualization of IFN was a feasible novel method with high accuracy that could assist in recognition of IFN and therefore potentially improve the treatment outcome of parotid tumor resection.

The Relationship Between the Retromandibular Vein and the Extratemporal Segment of the Facial Nerve: A Prospective Cadaveric Study of 24 Hemifaces

INTRODUCTION

Anatomical preservation and functional integrity of the facial nerve (FN) are the main concerns of parotid surgery. Even though a variety of anatomical landmarks have been proposed and widely utilized, temporal or permanent postoperative FN palsy is still a significant comorbidity of parotid surgery. Therefore, the literature must fully elucidate the consistency of the anatomical relationship between the FN and the retromandibular vein (RMV).

METHODS

We conducted a cadaveric study of 24 hemifaces to map the relationship between the FN and the RMV. Three distinct patterns were identified. Fourteen of the hemifaces were males, and 10 were females. Thirteen cadaveric dissections were performed on the right side and 11 on the left side.

RESULTS

Our study found three distinct patterns and proposed a classification system. Type I (66.7%) is when the nerve lies exclusively lateral to the RMV. Type II (29.2%) is when the FN lies superficial to the RMV, but its mandibular branch lies deep to the anterior branch of the RMV, and type III (4.1%) is when the FN lies exclusively medial to the RMV.

CONCLUSION

The FN and RMV relationship is not constant, and surgeons should be aware of every anatomical variation. Especially in cases where the FN is estimated to lie more in-depth to the level of the RMV, a retrograde approach may be required to avoid a FN injury.

Surgical treatment for a giant venous malformation of the parotid area

This report discusses the surgical treatment of a giant parotid venous malformation (VM) that had grown beyond the dimensions of the parotid gland, causing significant displacement. Special attention was paid to identifying the facial nerve, which was found to traverse the surface of the VM. Although, in our case, the facial nerve ran superficially on the VM, it is possible that a portion of it penetrated the mass. A two-stage excision and revision surgery strategy was employed due to the complexity of assessing deformities after removing the giant lesion. During the initial surgery, the displaced superficial lobe of the parotid gland was repositioned to its original location and carefully laid over the facial nerve, ensuring its safety during the subsequent procedure.

Ultrasonographic Localization of Parotid Gland Tumor Relative to the Facial Nerve Using Stensen's Duct Criterion

PURPOSE

During the preoperative evaluation of parotid gland tumors, 1 of the main concerns is to determine the location of the tumors in relation to the facial nerve. This study aims to assess the value of ultrasound for determination of the location of parotid gland tumors in relation to the facial nerve using Stensen's duct.

METHODS

This is a retrospective cross-sectional study at a single institute. The subjects who underwent preoperative ultrasound and parotidectomy for parotid gland tumors were included. The subjects with incomplete operative records or no reference standard for the location of parotid gland tumor were excluded. The primary predictor was ultrasound tumor location, which was defined as the location of parotid gland tumors determined by preoperative ultrasound as to whether the tumors were superficial or deep to the facial nerve. The operative records were used as the reference standard for the location of parotid gland tumors. The primary outcome was diagnostic performances of preoperative ultrasound in predicting the location of parotid gland tumors, which were calculated by comparing ultrasound tumor location to the reference standard. Covariates were sex, age, type of surgery, tumor size, and tumor histology. Data analysis involved descriptive and analytic statistics; P < .05 was considered significant.

RESULTS

One hundred and two of 140 eligible subjects met inclusion and exclusion criteria. There were 50 male and 52 female, with a mean age of 53.3 years. Ultrasound tumor location was classified as deep in 29 subjects, superficial in 50, and indeterminate in 23. The reference standard was deep in 32 subjects and superficial in 70. Indeterminate ultrasound tumor location results were grouped as either deep or superficial to make every possible cross table in which ultrasound tumor location results were presented as a dichotomy. The mean sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the ultrasound to predict the deep location of parotid tumors were 87.5, 82.1, 70.2, 93.6, and 83.8%, respectively.

CONCLUSIONS

Stensen's duct on ultrasound can be a useful criterion to determine the location of parotid gland tumor relative to the facial nerve.

Does three-dimensional intraglandular location predict malignancy in parotid tumors?

Tumors arising within the parotid encompass a heterogeneous mix of benign and malignant neoplasms and other tissue growths. The purpose of this study was to determine the association between the location of intraparotid masses and the risk of malignancy. A retrospective cohort study was performed of patients diagnosed with parotid tumors following open tumor excision. The primary predictor variable was the location of the epicenter of the tumor in three-dimensional space, as determined from preoperative imaging. Other variables were patient demographics and clinical parameters. The primary outcome variable was the final histopathologic diagnosis of a benign or malignant process. A χ² analysis was performed to test for any significant associations between demographic, clinical, and radiographic factors in relation to the outcome, and backwards stepwise logistic regression analysis was used to control for variables. Both increasing age (P = 0.002) and the presence of local pain (P = 0.020) were associated with malignancy. Tumors located anterior to the posterior border of the retromandibular vein had 2.18 times higher odds of malignancy (95% confidence interval 1.13-4.21; P = 0.020). Multivariate regression analysis suggested that patient age, the presence of pain, and tumor location anterosuperiorly and superoinferiorly could all assist in determining the odds of malignancy.

Preoperative Magnetic Resonance Image and Computerized Tomography Findings Predictive of Facial Nerve Invasion in Patients with Parotid Cancer without Preoperative Facial Weakness-A Retrospective Observational Study

Simple Summary

Facial nerve invasion in parotid cancer affects survival outcomes as well as functional outcomes after surgery-based treatment. Normal facial muscle function before surgery does not always exclude the possibility of involvement of the facial nerve by a tumor. Especially in patients without facial palsy, accurate evaluation of invasion before surgery is necessary to plan optimal facial nerve resection and reconstruction. Various findings are obtained from preoperative radiological findings, such as CT and MRI. We evaluated the role of these radiological findings in predicting nerve invasion. Large tumor, spiculated margin, and anterolateral location may suggest a high risk of nerve involvement even in patients with normal preoperative facial function. These findings may help surgeons to avoid unexpected facial nerve invasion and to make adequate surgical plans to get optimal oncological and functional outcomes.

Abstract

(1) Background: Facial nerve resection with reconstruction helps achieve optimal outcomes in the treatment of facial nerve invasion (FNI) of parotid cancer. Preoperative imaging is crucial to predict facial nerve reconstruction. The radiological findings of CT or MRI may predict FNI in the parotid cancer even without facial paralysis. Methods: We retrospectively reviewed the records of 151 patients without facial nerve paralysis before surgery who had undergone tumor resection. Previously untreated parotid cancers were included. (2) Results: The median follow-up duration was 62 months (range: 24–120 months). The FNI (+) group (n = 30) showed a significantly worse 5-year overall survival compared with the FNI (−) group (75.5 vs. 93.9%; hazard ratio = 4.19; 95% confidence interval: 1.74–10.08; p = 0.001). The tumor margin, tumor size, presence in the anterolateral parotid region (area 3), retromandibular vein involvement, distance from the stylomastoid foramen to the upper tumor margin, and a high tumor grade were significant factors related to FNI in the univariate analysis. A spiculated tumor margin, the tumor size (2.2 cm), and presence in area 3 were factors predicting FNI in the logistic regression model (p = 0.020, 0.005, and 0.050, respectively; odds ratio: 4.02, 6.40, and 8.16, respectively). (3) Conclusions: The tumor size (≥2.2 cm), spiculated margin, and presence in area 3 as presented in CT and MRI may help clinicians preoperatively predict FNI in patients with parotid cancer and establish an appropriate surgical plan.

Localization of Parotid Gland Tumors in Relation to the Intraparotid Facial Nerve on 3D Double-Echo Steady-State with Water Excitation Sequence

BACKGROUND AND PURPOSE

Reliable preoperative facial nerve mapping may help avoid or minimize facial nerve injury during parotid tumor resection. The purpose of this study was to investigate the diagnostic performance of the 3D double-echo steady-state with water excitation sequence in localizing parotid gland tumors through direct visualization of the intraparotid facial nerve in comparison with indirect methods of estimating the facial nerve location.

MATERIALS AND METHODS

We retrospectively reviewed 91 parotid gland tumors in 90 patients who underwent surgical resection and preoperative MR imaging, including the 3D double-echo steady-state with water excitation sequence. The tumor locations were categorized as deep or superficial on the basis of direct and 3 indirect methods: the facial nerve line, retromandibular vein, and Utrecht line. Surgical localization was considered the criterion standard. The diagnostic performance for localizing deep lobe lesions using direct and indirect methods was calculated and compared using the McNemar test.

RESULTS

Surgical localization confirmed 75 superficial lesions and 16 deep lesions. The interobserver variability of the 3D double-echo steady-state with water excitation sequence was excellent (κ = 0.870). The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for localizing deep lobe lesions using the 3D double-echo steady-state with water excitation method were 97.8%, 87.5%, 100%, 100%, and 97.4%, respectively. These findings were significantly higher than the facial nerve line in sensitivity, the retromandibular vein in sensitivity, and the Utrecht line in accuracy and specificity (P < .05). Overall, the direct method was the most accurate, sensitive, and specific in localizing parotid gland tumors.

CONCLUSIONS

We can achieve higher diagnostic performance in localizing parotid gland tumors by directly visualizing the intraparotid facial nerve using the 3D double-echo steady-state with water excitation sequence compared with indirect methods.

Value of Diffusion-Weighted Imaging Combined with Susceptibility-Weighted Imaging in Differentiating Benign from Malignant Parotid Gland Lesions

BACKGROUND The aim of this study was to investigate the diagnostic value of diffusion-weighted imaging (DWI) in combination with susceptibility-weighted imaging (SWI) for differentiating benign parotid gland lesions from malignant ones. MATERIAL AND METHODS This retrospective study was approved by the Ethics Committee of our hospital. A total of 36 patients (26 benign cases and 10 malignant cases) were confirmed by surgical pathology. The apparent diffusion coefficient (ADC), normalized ADC (ADCNormalized), intratumoral susceptibility signals (ITSS), and morphological characteristics were analyzed with SPSS 19.0 software. RESULTS The mean ADC values of parotid gland lesions was not different between malignant and benign lesions (P=0.07), while the differences between ADCNormalized (P=0.026) and ITSS grading (P=0.014) were statistically significant. Logistic regression analysis identified use of ADCNormalized and ITSS as the only independent predictor of malignant lesions (odds ratio 0.038; 95% confidence interval 0.001~0.988; P=0.011) and (odds ratio 4.867; 95% confidence interval 1.442~16.423; P=0.049), respectively. The optimum threshold of the ADCNormalized values was -0.45%, ITSS grade was 2, the corresponding areas under the receiver operating characteristic curve (AUC) were 0.750 and 0.787 respectively, and the combination of the 2 was 0.846. CONCLUSIONS DWI integrated with SWI can significantly improve the diagnostic efficacy in distinguishing benign from malignant parotid lesions.

The multiplanar analysis of the retromandibular vein in surgical planning for parotid gland tumors

OBJECTIVE

To analyze the effectiveness of the multiplanar analysis of the retromandibular vein in establishing the position of the parotid gland tumor and its relationship with the facial nerve, together with the most common radiological criteria (facial nerve line, Utrecht line, retromandibular vein and parapharyngeal space variations) using the magnetic resonance imaging.

STUDY DESIGN

Retrospective study SETTING: Tertiary Academic Hospital SUBJECTS AND METHODS: 128 preoperative magnetic resonances were analyzed to study preoperative tumor location (medial or lateral to the expected course of the facial nerve) based on comparison between the radiological criteria and the surgical findings.

RESULTS

FN line had the lowest accuracy at 77%, whereas the retromandibular vein achieved 85% accuracy and the UT line achieved accuracy of 93%. The retromandibular vein could not be identified in 11 cases (9%). The multiplanar evaluation of the retromandibular vein allowed us to identify it on almost all MR images (99% of cases) and reach 87% of accuracy. The parapharyngeal space evaluation achieved 92% of accuracy. In the subgroup of 66 cases where the neoplasms were strictly related to the main trunk, where the surgery entailed manipulation if situated laterally to the tumor, the multiplanar evaluation of the retromandibular vein reached 98% of accuracy and UT line achieved 94%.

CONCLUSIONS

The multiplanar modality, combined with the evaluation of the parapharyngeal space, is effective in helping the surgeon to achieve accurate planning: it enables the tumor to be located and the facial nerve course predicted with a good precision.

Correlation between preoperative predictions and surgical findings in the parotid surgery for tumors

Background

To compare preoperative CT/MRI based predictions with real surgical findings for deep lobe parotid gland surgery.

Methods

The study analyzed 122 parotidectomies (2004–2014) for benign tumor removal. The facial nerve, the Utrecht line, the Conn’s arc, and the retromandibular vein were used as landmarks for CT/MRI presurgical evaluation of patients. We assessed 106 CT images and 86 MRI images. The study compared preoperative evaluation of tumor location with its actual location that was revealed during the operation and assessed the importance of the landmarks.

Results

In general, the agreement between preoperative CT prediction and actual location of the parotid tumors was achieved in 88.7 % (n = 94/106) when facial nerve line was used as a landmark. However, out of 14 tumors in the deep lobe only 5 were located correctly (35.7 %). Of the other existing CT landmarks, none showed more precision over others. The agreement between MRI based prediction and surgical results on actual location of the tumor was achieved in 94.2 %. Out of 12 MRI-investigated tumors in the deep lobe nine were located correctly that gives 75 % agreement with surgical results.

Conclusion

Our data suggests that no existing CT landmark can be accepted as completely reliable in cases when selective deep lobe parotidectomy is planned. If tumor location is suspected in the deep lobe of the gland, MRI imaging is necessary to confirm the diagnosis. An operating surgeon should be prepared that in some cases the true location of the tumor would be revealed only during surgery.

Novel differential diagnostic method for superficial/deep tumor of the parotid gland using ultrasonography

BACKGROUND

The purpose of this study was to prepare the ultrasonographic diagnostic criteria on parotid tumors for preoperative differentiation of superficial and deep tumors.

METHODS

We evaluated 154 patients with a benign parotid tumor who underwent surgery. The minimum thickness of normal parotid gland tissue between the parotideomasseteric fascia and tumor (minimum fascia-tumor distance [MFTD]) was measured on preoperative ultrasonography and compared among tumors at different locations, and the optimum cutoff value to differentiate a deep tumor was identified.

RESULTS

The MFTD showed significant differences between superficial and deep tumors and between inferior pole and deep tumors. The sensitivity, specificity, and accuracy of an MFTD ≥3 mm for the differentiation of deep tumors were 85%, 91%, and 89%.

CONCLUSION

A tumor with an MFTD ≥3 mm on preoperative ultrasonography is very likely to be a deep tumor based on a new differentiation method for deep parotid tumors considering those present at other locations.

Do magnetic resonance imaging and ultrasound add anything to the preoperative workup of parotid gland tumors?

PURPOSE

To assess the additional value of magnetic resonance imaging (MRI) and ultrasound (US) to physical examination (PE) and fine needle aspiration cytology (FNAC) in the preoperative determination of the location and histology of parotid gland tumors.

PATIENTS AND METHODS

Prospectively, 99 patients with 77 benign and 22 malignant lesions were included; 82 underwent parotidectomy. FNAC was performed in 88 patients. On PE, the location of the tumor was predicted. Eighty-nine patients had MRI and 47 US. Various characteristics and the presumed diagnosis were assessed. Furthermore, the location of the tumor in relation to the facial nerve was predicted. The results were compared with the definite histology and the location during surgery.

RESULTS

Of the MRI characteristics, incomplete demarcation from normal parotid gland tissue showed the highest positive predictive value (PPV) for malignancy of 0.48. Of the US characteristics, enlarged lymph nodes yielded the highest PPV for malignancy of 0.5. Cytology correctly predicted the benign or malignant nature of the tumor in all cases. Superficial location was well predicted on PE with a PPV of 0.8, slightly better on MRI (PPV of 0.87), and worse on US (PPV of 0.7).

CONCLUSION

FNAC is the only accurate investigation for classifying a parotid gland tumor as benign or malignant. Palpation and MRI are superior to US in predicting tumor location. Because the results for palpation and MRI are almost equal, MRI should only be reserved for specific cases, and not routinely requested.

Use of cross-sectional imaging in predicting surgical location of parotid neoplasms

OBJECTIVE

The purpose of this study was to determine the diagnostic accuracy of using the retromandibular vein as seen on cross-sectional imaging to help differentiate superficial lobe from deep lobe tumors.

METHODS

Of the patients who had parotid neoplasms between January 1997 and July 2002, we were able to identify 44 patients with preoperative imaging studies that were available for evaluation. The films were reviewed by a single head and neck radiologist to determine whether the neoplasms involved the superficial, deep, or both lobes of the parotid gland (total). The lateral margin of the retromandibular vein was used as a marker for the facial nerve, since the nerve is not always visible on CT and MRI scans. The radiologist's findings were then compared with the findings during surgery. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of predicting the location of neoplasms were then calculated.

RESULTS

For lesions in the superficial lobe, cross-sectional imaging was able to predict the location of the neoplasm with a sensitivity of 0.91 (95% CI, 0.70-0.98), specificity of 0.86 (95% CI, 0.63-0.96), PPV of 0.88 (95% CI, 0.67-0.97), and NPV of 0.90 (95% CI, 0.67-0.98). For lesions in both lobes (total), cross-sectional imaging was able to predict the location of the neoplasm with a sensitivity of 0.94 (95% CI, 0.68-0.99), specificity of 0.89 (95% CI, 0.71-0.97), PPV of 0.83 (95% CI, 0.58-0.96), and NPV of 0.96 (95% CI, 0.78-0.99).

CONCLUSION

Use of the retromandibular vein as a marker for the facial nerve is a sensitive method for identifying the location of parotid gland neoplasms on cross-sectional imaging. This supports the accuracy of using preoperative imaging to detect the position of parotid neoplasms with respect to the facial nerve.

Use of Cross-Sectional Imaging in Predicting Facial Nerve Sacrifice during Surgery for Parotid Neoplasms

BACKGROUND

Neoplasms of the parotid gland are difficult management issues because of the wide variation in their biological behavior and the potential for sacrifice of the facial nerve during resection. Because of the significant associated morbidity, prediction of facial nerve sacrifice is critically important for planning surgical procedures and preoperative counseling of patients. We hypothesize that along with the knowledge of the tumor type we would be able to accurately predict the likelihood of facial nerve sacrifice using cross-sectional imaging.

METHODS

All patients included in this study were previously untreated patients with parotid neoplasms operated on between January 1997 and July 2002. Only those patients with an available preoperative imaging were included and this resulted in 44 patients for review. Nine patients with preoperative deficits in facial nerve function were excluded from this study since these patients would require facial nerve sacrifice regardless of the radiological prediction. The prediction of facial nerve sacrifice was determined using a prediction of tumor location and an algorithm. The predicted results were compared to the operative record.

RESULTS

For all lesions, cross-sectional imaging predicted the need for sacrifice of the facial nerve with a sensitivity of 0.83 (95% CI, 0.36-0.99), specificity of 0.90 (95% CI, 0.72-0.97), PPV of 0.63 (95% CI, 0.26-0.90), and NPV of 0.96 (95% CI, 0.79-0.99). For malignant lesions only, prediction of sacrifice of the facial nerve had a sensitivity of 0.83 (95% CI, 0.36-0.99), specificity of 0.80 (95% CI, 0.51-0.95), PPV of 0.63 (95% CI, 0.26-0.90), and NPV of 0.92 (95% CI, 0.62-0.99).

CONCLUSION

Cross-sectional imaging and application of our algorithm is a sensitive method for identifying patients with parotid neoplasms who require facial nerve sacrifice. CT and MRI have a high negative predictive value for facial nerve sacrifice.