Sugoto Mukherjee

Oral Cavity and Oropharyngeal Squamous Cell Cancer: Key Imaging Findings for Staging and Treatment Planning

The imaging findings in squamous cell carcinoma (SCC) of the oral cavity and oropharynx vary widely, depending on the site of origin of the primary tumor and the extent of its involvement of other regions. Knowledge of the complex anatomy of the oral cavity and oropharynx, as well as the most common routes by which SCC spreads from various anatomic sites, allows the radiologist to accurately determine the extent of disease and help clinicians plan appropriate treatment. SCCs that originate in the oral cavity tend to behave differently than those that originate in the oropharynx, with the latter group exhibiting more aggressive growth. Furthermore, primary tumors in certain anatomic subsites within the oral cavity or oropharynx have a greater propensity to spread by direct extension along muscle, bone, or neurovascular bundles or to be disseminated along lymphatic drainage pathways to regional or distant nodes. Imaging findings of deep muscular, neurovascular, osseous, or nodal involvement are indicative of an advanced stage of disease for which management options are limited.

Imaging of the Facial Nerve

A variety of congenital, traumatic, vascular, inflammatory, and neoplastic processes may affect the facial nerve. Prudent use of CT and MR imaging combined with a complete understanding of facial nerve anatomy helps in narrowing the differential diagnosis. The precise anatomic course of the facial nerve must be charted in patients who undergo middle ear surgery. Also of great importance is recognition of the fact that the facial nerve may be affected in cancers of the head and neck by perineural spread. This article reviews the anatomy of the facial nerve and relevant, current clinical evaluation and imaging strategies.

Magnetic resonance angiography of the extracranial carotid system.

Objectives: To discuss the role of magnetic resonance angiography (MRA) in the evaluation of the extracranial carotid system with an emphasis on atherosclerosis and to briefly address the role of magnetic resonance imaging in imaging of carotid atherosclerotic plaque. Methods: Literature and institutional review. Discussion: The North American Symptomatic Carotid Endarterectomy Trial and European Carotid Surgery Trial studies have emphasized the importance of recognition and treatment of carotid stenosis in the prevention of ischemic stroke. Magnetic resonance angiography is a viable tool in the screening and quantification of this entity. Both time of flight and contrast-enhanced MRA techniques are available for clinical use, each with distinct advantages and limitations. A thorough understanding of these is vital for correct performance and interpretation of these studies. Plaque imaging with magnetic resonance imaging offers new insights into the pathophysiology of the atherosclerotic process and may be used in the future to monitor response to lipid-lowering drug therapy. Conclusion: Magnetic resonance angiography is a robust imaging technique for evaluation of the extracranial carotid circulation. The radiologist must be aware of the advantages and limitations of the different techniques available. Contrast-enhanced MRA is now the most widely performed technique. It can be used to replace digital subtraction angiography in the evaluation of carotid stenosis in most clinical settings.

Imaging of Vascular Compression Syndromes.

Trigeminal neuralgia, hemifacial spasm, vestibulocochlear neuralgia and glossopharyngeal neuralgia represent the most common neurovascular compression syndromes. Repeated vascular pulsations at the vulnerable transitional zone of the individual cranial nerves lead to focal axonal injury and demyelination. High-resolution 3-D T2-weighted MR imaging is essential in detecting and mapping neurovascular compression for directed therapy. Knowledge of the specific nerve root exit, the transitional zones, and the adjacent vasculature is critical in proper management. Treatment options for these neurovascular compressions syndromes run the gamut from medical therapy to stereotactic radiosurgery to botulinum injections and to surgical decompression.

Imaging case of the month: Abnormalities of the cochlear nerves and internal auditory canals in pontine tegmental cap dysplasia.

Pontine tegmental cap dysplasia (PTCD) is a recently described hindbrain malformation characterized by pontine hypoplasia and ectopic dorsal transverse pontine fibers (1). To date, a total of 19 cases of PTCD have been published, all patients had sensorineural hearing loss (SNHL). We contribute 1 additional case of PTCD with SNHL with and VIIIth cranial nerve and temporal bone abnormalities using dedicated magnetic resonance (MR) and high-resolution temporal bone computed tomographic (CT) images.

Duplication of the internal auditory canal: radiographic imaging case of the month.

As many as 40% of patients with congenital sensorineural hearing loss will have a structural inner ear malformation identified on a temporal bone imaging study (1). Anomalies of the internal auditory canal (IAC) are rare and have been reported to account for only 12% of all congenital temporal bone abnormalities. Internal auditory canal abnormalities may be associated with hypoplasia or aplasia of the vestibulocochlear nerve with resultant sensorineural hearing loss. Sensitive magnetic resonance imaging (MRI) techniques are able to examine in great detail the anatomy and contents of the IAC and to diagnose aplasia or hypoplasia of the vestibular and/or cochlear nerves (2). Duplication of the IAC is an extremely rare finding involving a redundant bony canal extending from the cerebellopontine angle through the otic capsule bone toward the labyrinth or cochlea. A narrow, duplicated IAC can be associated with congenital sensorineural hearing loss secondary to aplasia of the vestibulocochlear nerve.

Isolated contralateral sudden sensorineural hearing loss: an unusual manifestation of pontine infarct.

Unilateral, acute onset sensorineural hearing loss (“sudden sensorineural hearing loss” [SSNHL]) as an isolated event without other associated neurological deficits usually results from a lesion of the cochlea. Lesions in the ascending central auditory pathways cranial to the cochlear nucleus seldom result in unilateral hearing loss due to decussation of the central auditory pathways at multiple levels. We describe a patient with a tiny acute infarct in the right pons resulting in isolated acute onset left-sided SSHNL, without any other associated acute neurological deficits.

Open Reduction Internal Fixation for Midline Mandibulotomy: Lag Screws vs Plates

IMPORTANCEnMidline mandibulotomy is a common approach for resection of head and neck oral cavity and oropharyngeal tumors; however, there are limited data available on the outcomes of lag screw vs plate fixation.nnnOBJECTIVEnTo compare outcomes for midline mandibulotomy open reduction and internal fixation using plates vs lag screw technique.nnnDESIGN, SETTING, AND PARTICIPANTSnRetrospective cohort study at a tertiary care academic medical center of patients undergoing midline mandibulotomy for head and neck tumor resection over a 6-year period.nnnINTERVENTIONSnMandibular fixation using lag screws or plates.nnnMAIN OUTCOMES AND MEASURESnThe medical records and computed tomographic (CT) scans of patients undergoing midline mandibulotomy for head and neck tumor resection over a 6-year period were retrospectively reviewed. The postoperative CT scans were reviewed by a neuroradiologist who graded the fusion site on a scale of 0 to 2 using a 2-pass method. The rates and grades of union were compared, as well as several factors that affect healing, for fixations performed with plates vs lag screws.nnnRESULTSnThirty-seven patients were included. The overall rate of radiologic union was 90% (9 out of 10) for lag screw technique and 41% (11 out of 27) for plates (Pu2009=u2009.01). The average grade of radiologic union was 1.3 for lag screws and 0.67 for plates (Pu2009=u2009.04). Hardware exposure occurred in 4 (15%) of the plate group and fistulae formed in 3 (11%); neither complication occurred in the lag screw group. In univariate analysis, both presence of dentition (odds ratio [OR], 5.50 [95% CI, 1.33-22.73]; Pu2009=u2009.02) and plate technique (OR, 13.09 [95% CI, 1.45-11.62]; Pu2009=u2009.02) were significantly associated with nonunion. In multivariate analysis, plate technique had an OR of 8.32 (95% CI, 0.85-81.75) for nonunion (Pu2009=u2009.07).nnnCONCLUSIONS AND RELEVANCEnFixation of midline mandibulotomy with lag screws results in a significantly increased rate of radiologic union compared with plates. Lag screws were also significantly better at achieving radiologic union in patients who underwent postoperative radiation, and the rates of fistula formation and hardware exposure were lower. Thus, lag screw fixation of midline mandibulotomy should be considered an excellent option, especially when patients will undergo postoperative adjuvant therapy and in patients at high risk for wound complications.

Thyroid and Parathyroids

The thyroid gland is an essential component of our endocrine system and regulates a wide range of critical metabolic functions. Both focal and diffuse thyroid disorders can impact function. The parathyroid glands regulate serum calcium levels. Parathyroid evaluation is almost always done in the setting of hyperparathyroidism and hypercalcemia. A combination of imaging techniques is used to evaluate thyroid and parathyroid pathology and function, including ultrasound, CT, MRI, and radionuclide imaging.

Temporal Bone and Skull Base

The external auditory canal is comprised of an outer cartilaginous and an inner bony part and is covered entirely by skin. The tympanic membrane is located in an osseous groove (tympanic annulus) and forms a complex angle, roughly about 55° with the sagittal plane. The normal tympanic membrane may not be visible on CT scans. The anterosuperior portion of the tympanic membrane is comprised of the pars flaccida, and the remainder is the pars tensa. The pars flaccida is the most common site of cholesteatoma formation. The handle of the malleus is attached to the pars tensa (Fig. 8.1).