Imaging Evaluation of the Suprahyoid Neck

Fascial layers encountered in the lateral skull base region: A cadaveric and radiological analysis

BACKGROUND

In our experience, the anterior carotid sheath forms an important plane of dissection when excising temporal bone region cancers. However, its anatomical composition, relationships, and radiological appearance remains unclear.

METHODS

Eight sides of cadaveric heads were dissected. Anatomical findings were correlated with a high-resolution baseline T1 MRI.

RESULTS

The anterior carotid sheath was formed by the tensor-vascular-styloid fascia, stylopharyngeal fascia, buccopharyngeal fascia (BPF), and longus capitis fascia (LCF), and appeared as a hypointense line on MRI. Not previously described, the glossopharyngeal nerve pierced the sheath 9.0 mm (SD 2.1 mm) below the skull base and traveled through its LCF and BPF layers to exit near the pharynx.

CONCLUSION

Multiple fascial layers formed the anterior carotid sheath at the skull base, and this was radiologically identifiable. Further studies are required to validate findings and investigate the role this fascial plane has in forming an effective barrier to spread of malignancy.

ACR Appropriateness Criteria® Neck Mass-Adenopathy

A palpable neck mass may be the result of neoplastic, congenital, or inflammatory disease. Older age suggests neoplasia, and a congenital etiology is more prevalent in the pediatric population. The imaging approach is based on the patient age, mass location, and clinical pulsatility. Underlying human papillomavirus-related malignancy should be considered in all age groups. Although the imaging appearance of some processes in the head and neck overlap, choosing the appropriate imaging examination may allow a specific diagnosis, or a limited differential diagnosis. Tissue sampling is indicated to confirm suspected malignancy. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

CT of the Neck: Image Analysis and Reporting in the Emergency Setting

Interpreting findings seen at CT of the neck is challenging owing to the complex and nuanced anatomy of the neck, which contains multiple organ systems in a relatively small area. In the emergency department setting, CT is performed to investigate acute infectious or inflammatory symptoms and chronic processes. With few exceptions, neck CT should be performed with intravenous contrast material, which accentuates abnormally enhancing phlegmonous and neoplastic tissues and can be used to delineate any abscesses or necrotic areas. As part of the evaluation, the vascular structures and aerodigestive tract must be scrutinized, particularly for patency. Furthermore, although the patient may present because of symptoms that suggest non-life-threatening conditions involving structures such as the teeth or salivary glands, there may be serious implications for other areas, such as the orbits, brain, and spinal cord, that also may be revealed at the examination. With a focus on the emergency setting, the authors propose using an approach to interpreting neck CT findings whereby 12 areas are systematically evaluated and reported on: the cutaneous and subcutaneous soft tissues, aerodigestive tract and adjacent soft tissues, teeth and periodontal tissues, thyroid gland, salivary glands, lymph nodes, vascular structures, bony airspaces, cervical spine, orbits and imaged brain, lung apices, and superior mediastinum. The use of a systematic approach to interpreting neck CT findings is essential for identifying all salient findings, recognizing and synthesizing the implications of these findings to formulate the correct diagnosis, and reporting the findings and impressions in a complete, clear, and logical manner.Online supplemental material is available for this article.^©RSNA, 2019.

Pterygoid muscle abscess secondary to parapharyngeal space lymphadenitis

We describe the case of a young boy with severe clinical symptoms which mimicked several findings consistent with a peritonsillar abscess (PTA). After the patient exhibited no improvement with medical management, imaging revealed an intramuscular medial pterygoid abscess secondary to parapharyngeal space lymphadenitis. This is the first reported case of a patient with a medial pterygoid abscess secondary to lymphadenitis. We also describe a minimally invasive surgical approach for incision and drainage of the abscess that has not previously been described in the literature.

Role of Computed Tomography (CT) in Localisation and Characterisation of Suprahyoid Neck Masses

Background

Suprahyoid neck lesions are difficult to assess only by means of clinical inspection and therefore imaging techniques are required to precisely evaluate suprahyoid neck spaces. The aim of this study was to evaluate the distinctive role of computed tomography in the assessment of anatomical source and pathological type of masses involving the suprahyoid neck spaces.

Material/Methods

Sixty patients presenting with suprahyoid neck masses underwent computed tomography of the neck. The CT findings were correlated with histopathological findings and a final diagnosis was made.

Results

Overall, male preponderance was seen except in the case of parotid space lesions where female predominance was seen. The most common aetiology was squamous cell carcinoma and the majority of cases (30%) were seen in patients aged 41–50 years. The majority of lesions were found in the pharyngeal mucosal space (n=16) with squamous cell carcinoma being the most common pathology. In the parotid space, pleomorphic adenoma and in the prestyloid parapharyngeal space, squamous cell carcinoma were the most common lesions, respectively. In the retropharyngeal space, an equal incidence of malignant and inflammatory aetiologies was seen. Abscesses were the most common lesions in the prevertebral space. The pleomorphic adenoma was the most common benign tumour and was also the second most common tumour in the suprahyoid neck spaces. CT had an excellent correlation with histopathological findings with sensitivity of 96.4%, specificity of 100%, positive predictive value of 100% and a negative predictive value of 91.67%.

Conclusions

Computed tomography definitely has a major role to play in the evaluation of suprahyoid neck masses as it has an excellent correlation with post-operative histopathological diagnosis.

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.