Imaging of Paranasal Sinuses and Anterior Skull Base and Relevant Anatomic Variations

Imaging of Skull Base Tumors

The skull base provides a platform for supporting the brain while serving as a conduit for major neurovascular structures. In addition to malignant lesions originating in the skull base, there are many benign entities and developmental variants that may simulate disease. Therefore, a basic understanding of the relevant embryology is essential. Lesions centered in the skull base can extend to the adjacent intracranial and extracranial compartments; conversely, the skull base can be secondarily involved by primary extracranial and intracranial disease. CT and MRI are the mainstay imaging methods and are complementary in the evaluation of skull base lesions. Advances in cross-sectional imaging have been crucial in the management of patients with skull base pathology, as this represents a complex anatomical area that is hidden from direct clinical exam. Furthermore, the clinician must rely on imaging studies for therapy planning and to monitor treatment response. It is crucial to have a thorough understanding of skull base anatomy and its various pathologies, as well as to recognize the appearance of treatment-related changes. In this review, we aim to describe skull base tumors and tumor-like lesions in an anatomical compartmental approach and present imaging methods that aid in diagnosis, management, and follow-up.

Imaging of pediatric calvarial and skull base tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee/ASPNR White Paper

A standardized imaging protocol for pediatric oncology patients is essential for accurate and efficient imaging, while simultaneously promoting collaborative understanding of pathologies and radiologic assessment of treatment response. The objective of this article is to provide standardized pediatric imaging guidelines and parameters for evaluation of tumors of the pediatric orbit, calvarium, skull base, and temporal bone. This article was drafted based on current scientific literature as well as consensus opinions of imaging experts in collaboration with the Children's Oncology Group Diagnostic Imaging Committee, Society of Pediatric Radiology Oncology Committee, and American Society of Pediatric Neuroradiology.

Imaging of Paranasal Sinus Infections in Children: A Review

Paranasal sinuses (PNS) infections are common in children. They may cause common and well-known complications, but also, unusual and potentially devastating complications. Diagnosing PNS infections and complications in children requires knowledge of the unique anatomy of the nasal cavity and the PNS. In fetal life, nasal mucosa evaginations into the lateral nasal walls initiate the development of the PNS. The PNS continue to develop after birth and complete their maturation and pneumatization at different ages during childhood which makes the pattern of PNS infections determined by patient age. Complications are caused by direct spread of the infection to the orbit, face, intracranial or osseous structures or hematogenous spread of the infection to the intracranial structures. Emergent imaging studies are often necessary in the evaluation of the complications in pediatric patients when the symptoms persist for 10 days and/or if there is evidence of intracranial or orbital complications. In addition, immunocompromised children are especially vulnerable to developing unusual complications. Computed tomography (CT) is excellent for determining whether there is intraorbital extension of PNS disease. However, when the infection approaches the orbital apex, a magnetic resonance imaging (MRI) study with contrast is necessary to assess spread into the cavernous sinus and the intracranial compartment. The goal of this manuscript is to review and characterize imaging findings of PNS infections using CT and MRI allowing determination of the extent of PNS infections and their common and unusual complications in children. In addition, a summary of the development of the normal PNS is provided.

Computed tomography assessment of anterior ethmoidal canal dehiscence: An interobserver agreement study and review of the literature

PURPOSE

The anterior ethmoidal artery can be injured in functional endoscopic sinus surgery. The ability of computed tomography (CT) to identify dehiscence of the anterior ethmoidal canal (AEC) has not been widely evaluated. The aim of this study was to evaluate the interobserver agreement in the CT assessment of AEC dehiscence.

METHODS

We conducted a retrospective review of consecutive CT scans of the paranasal sinuses (PNS) between January 1, 2012, and December 31, 2012. Two neuroradiologists separately assessed the presence of AEC dehiscence, the presence of PNS opacification, and the best CT plane to evaluate the AEC. Statistical analysis included descriptive analysis and interobserver agreement (kappa coefficient).

RESULTS

The AEC was below the skull base in 199 (22.3%) cases. Dehiscence of the AEC was found in 13.2% for reader 1 and in 7.3% for reader 2. The interobserver agreement for identification of AEC dehiscence was only fair (κ = 0.246). The interobserver agreement for the AEC dehiscence in cases with opacification of ethmoidal air cells was substantial (κ = 0.754).

CONCLUSION

The suboptimal interobserver agreement could potentially limit the usefulness of CT scans for routine assessment of AEC dehiscence. In patients with PNS opacification, CT scans could still add valuable information regarding AEC dehiscence.

Imaging review of the anterior skull base

The anterior skull base (ASB) is intimately associated with the unique soft tissue subtypes of the nasal cavity, paranasal sinuses, orbits, and intracranial compartment. Pathology involving the ASB is rare but the causes are manifold and can be broadly subdivided into those intrinsic to the skull base and processes extending from below or above. Sinonasal pathology is the most commonly encountered and poses significant management challenges that rely heavily on accurate interpretation of the radiological findings. We illustrate the normal anatomy of the ASB and present a cross-sectional imaging review of the pathological entities that may be encountered, focusing on the specific features that will impact on clinical and surgical management.