Skull base osteomyelitis imaging.

PURPOSE OF REVIEW: Skull base osteomyelitis (SBO) is a challenging entity to diagnose and treat. The goal of this review is to summarize the imaging findings of SBO and present these in the context of recent studies on imaging of SBO. RECENT FINDINGS: This review discusses the clinical presentation, pathophysiology and imaging appearances of SBO. The review further emphasizes the results of latest studies on imaging of SBO, and the role of different modalities in diagnosis and evaluation of disease course and treatment response. Brief discussion on differential diagnoses from an imaging standpoint is also included. SUMMARY: Various imaging modalities play different and complimentary roles in diagnosis and management of SBO, which are discussed in this review.

Heavily calcified parapharyngeal space mesenchymal chondrosarcoma: Imaging and pathological findings and a review of the literature.

Parapharyngeal space (PPS) masses are relatively rare lesions of the head and neck, and account for 0.5-1.5% of head and neck lesions. The most common lesion to occur in the PPS is a benign salivary neoplasm, typically pleomorphic adenoma either from the deep parotid or from ectopic parotid tissue rests within the PPS. A calcified or ossified mass in this location is exceedingly rare, but a calcified variant of pleomorphic adenoma has been reported. In this study, we present a patient with a heavily calcified PPS mesenchymal chondrosarcoma with an unusual presentation. We discuss the imaging and pathologic findings followed by a review of the current literature.

Neuroimaging of the Pituitary Gland: Practical Anatomy and Pathology.

The pituitary gland is a small endocrine organ located within the sella turcica. Various pathologic conditions affect the pituitary gland and produce endocrinologic and neurologic abnormalities. The most common lesion of the pituitary gland is the adenoma, a benign neoplasm. Dedicated MR imaging of the pituitary is radiologic study of choice for evaluating pituitary gland and central skull region. Computed tomography is complimentary and allows for identification of calcification and adjacent abnormalities of the osseous skull base. This review emphasizes basic anatomy, current imaging techniques, and highlights the spectrum of pathologic conditions that affect the pituitary gland and sellar region.

Critical illness-associated cerebral microbleed in a patient with sickle cell disease: A case report and review of the literature.

Critical illness-associated cerebral microbleed (CICM) is a relatively rare and newly described condition. It can occur in critically ill ICU patients and can be secondary to many underlying etiologies. CICM is associated with high mortality and permanent neurologic deficits in surviving patients. Distribution of cerebral microhemorrhages in neuroimaging findings is critical for accurate diagnosis of this condition. Here, we present an ICU admitted patient with sickle cell disease crisis and CICM and will discuss their clinically and radiologically distinct phenomenon followed by a review of current literature.

Pseudohypoxic Brain Swelling: Report of 2 Cases and Introduction of the Lentiform Rim Sign as Potential MRI Marker.

BACKGROUND: A rare but important complication related to otherwise uneventful brain and spine surgery is becoming more recognized and more frequently reported in the medical literature. This has been variably labeled as pseudohypoxic brain swelling or postoperative hypotension-associated venous congestion. This poorly understood condition occurs in the setting of surgical intervention and is thought to be related to cerebrospinal fluid leak or evacuation, decreased intracranial pressure, and subsequent development of deep venous congestion affecting the basal ganglia, thalami, and cerebellum. Clinically, patients may have global neurologic deficit and outcomes range from full recovery to vegetative state or death. The imaging correlate includes atypical edema, infarction, or hemorrhage and can overlap the appearance of diffuse hypoxic injury, for which this condition can be mistaken both clinically and radiologically. Although this deep brain tissue edema can be associated with other signs of cerebrospinal fluid hypotension such as dural thickening, brain sagging, and cerebellar herniation, it can be isolated, making the diagnosis challenging. CASE DESCRIPTION: We present 2 cases of unexpected clinical deterioration occurring in patients with otherwise uncomplicated neurosurgery, 1 with craniotomy and the other with lumbar spine intervention. Both patients exhibit similar appearing edema in the deep gray structures on postoperative magnetic resonance imaging scans. In addition to reviewing the prior literature and imaging findings, we evaluate the imaging findings to determine if there are unique features or signatures that might allow differentiation of PHBS from hypoxic-ischemic encephalopathy. CONCLUSIONS: The lentiform rim sign can be helpful for differentiation of pseudohypoxic brain swelling versus hypoxic-ischemic encephalopathy.

Spontaneous "pneumo-apoplexy" as a presentation of pituitary adenoma.

Cases of spontaneous CSF leak associated with pituitary tumor apoplexy are uncommon in the literature with pneumocephalus or pneumosella being rare, especially spontaneous occurrence of pneumocephalus being extremely rare. We present a case of pituitary macroadenoma apoplexy resulting in spontaneous CSF leak and a large volume of intra-tumoral gas. A 65-year-old female presented with severe headache, profuse rhinorrhea and acute vision loss and was found to have a large sellar and suprasellar lesion with air and hemorrhage with mild peripheral enhancement. The patient underwent trans-sphenoidal tumor resection and repair of skull base for CSF leak with nasoseptal flap placement. Pathology demonstrated a pituitary adenoma exhibiting immunoreactivity for ACTH. To our best knowledge, our case is the first report of features of pituitary tumor apoplexy with hemorrhage and pneumosella, which could be summarized by the term "pneumo-apoplexy".

Imaging of Inflammatory Disorders of Salivary Glands.

Sialadenitis is among the most common conditions that affect the salivary glands. Inflammation of the salivary glands occurs as the end result of a variety of pathologic conditions, including infectious, autoimmune, and idiopathic causes. Clinically, inflammation of the salivary gland causes pain and localized swelling. The presentation may be acute or chronic, and can be recurrent. Because there is significant overlap of underlying disease mechanisms and clinical presentations, radiologic evaluation often plays a significant role in evaluation. This article is a brief review of sialadenitis, including disease mechanisms, causes, and the practical imaging of the salivary glands.

Prolonged treatment with bevacizumab is associated with brain atrophy: a pilot study in patients with high-grade gliomas.

Bevacizumab is widely used for treatment of high-grade gliomas and other malignancies. Because bevacizumab has been shown to be associated with neurocognitive decline, this study is designed to investigate whether prolonged treatment with bevacizumab is also associated with brain atrophy. We identified 12 high-grade glioma patients who received bevacizumab for 12 months at the first recurrence and 13 matched controls and blindly compared the volumes of the contralateral hemispheres and contralateral ventricle in these two groups at baseline and after 12 ± 2 months of the baseline scan by two independent analyses. The volumes of the contralateral hemispheres and ventricles did not differ significantly between the two groups at baseline. Whereas, in the control group the volumes of the contralateral hemisphere changed subtly from baseline to follow-up (p = 0.23), in the bevacizumab-treated group the volumes significantly decreased from baseline to follow-up (p = 0.03). There was significant increase in the contralateral ventricle volume from base line to follow-up scans in both the control group (p = 0.01) and in the bevacizumab group (p = 0.005). Both the absolute and the percentage changes of contralateral hemisphere volumes and contralateral ventricular volumes between the two patient groups were statistically significant (p < 0.05). Results of this study demonstrate prolonged treatment with bevacizumab is associated with atrophy of the contralateral brain hemisphere.

Practical imaging of the parotid gland.

The parotid gland may be affected by numerous pathologies, and physicians from many different medical and surgical specialties request parotid imaging. Mastering the typical imaging features of various types of parotid pathology is facilitated by understanding how various diseases produce their characteristic imaging findings. In this review article, we present succinct overviews of the normal anatomy and the common pathologies of the parotid gland and recommend a practical approach to differential diagnosis that can be easily implemented in day-to-day radiology practice.

Neurodegeneration with Brain Iron Accumulation: Clinicoradiological Approach to Diagnosis.

Discovery of genetic abnormalities associated with neurodegeneration with brain iron accumulation (NBIA) has led to use of a genetic-based NBIA classification schema. Most NBIA subtypes demonstrate characteristic imaging abnormalities. While clinical diagnosis of NBIA is difficult, analysis of both clinical findings and characteristic imaging abnormalities allows accurate diagnosis of most of the NBIA subtypes. This article reviews recent updates in the genetic, clinical, and imaging findings of NBIA subtypes and provides a practical step-by-step clinicoradiological algorithm toward clinical diagnosis of different NBIA subtypes.

Observer reliability of arteriovenous malformations grading scales using current imaging modalities.

OBJECT: The aim of this study was to examine observer reliability of frequently used arteriovenous malformation (AVM) grading scales, including the 5-tier Spetzler-Martin scale, the 3-tier Spetzler-Ponce scale, and the Pollock-Flickinger radiosurgery-based scale, using current imaging modalities in a setting closely resembling routine clinical practice. METHODS: Five experienced raters, including 1 vascular neurosurgeon, 2 neuroradiologists, and 2 senior neurosurgical residents independently reviewed 15 MRI studies, 15 CT angiograms, and 15 digital subtraction angiograms obtained at the time of initial diagnosis. Assessments of 5 scans of each imaging modality were repeated for measurement of intrarater reliability. Three months after the initial assessment, raters reassessed those scans where there was disagreement. In this second assessment, raters were asked to justify their rating with comments and illustrations. Generalized kappa (κ) analysis for multiple raters, Kendall's coefficient of concordance (W), and interclass correlation coefficient (ICC) were applied to determine interrater reliability. For intrarater reliability analysis, Cohen's kappa (κ), Kendall's correlation coefficient (tau-b), and ICC were used to assess repeat measurement agreement for each rater. RESULTS: Interrater reliability for the overall 5-tier Spetzler-Martin scale was fair to good (ICC = 0.69) to extremely strong (Kendall's W = 0.73) on initial assessment and improved on reassessment. Assessment of CT angiograms resulted in the highest agreement, followed by MRI and digital subtraction angiography. Agreement for the overall 3-tier Spetzler-Ponce grade was fair to good (ICC = 0.68) to strong (Kendall's W = 0.70) on initial assessment, improved on reassessment, and was comparable to agreement for the 5-tier Spetzler-Martin scale. Agreement for the overall Pollock-Flickinger radiosurgery-based grade was excellent (ICC = 0.89) to extremely strong (Kendall's W = 0.81). Intrarater reliability for the overall 5-tier Spetzler-Martin grade was excellent (ICC > 0.75) in 3 of the 5 raters and fair to good (ICC > 0.40) in the other 2 raters. CONCLUSION: The 5-tier Spetzler-Martin scale, the 3-tier Spetzler-Ponce scale, and the Pollock-Flickinger radiosurgery-based scale all showed a high level of agreement. The improved reliability on reassessment was explained by a training effect from the initial assessment and the requirement to defend the rating, which outlines a potential downside for grades determined as part of routine clinical practice to be used for scientific purposes.

Practical anatomy of the central skull base region.

The central skull base region represents a complex intersection between the intracranial compartment, the osseous foundation of the skull base, the orbits, the paranasal sinuses, and the suprahyoid neck. A modern radiologic approach to this region should take into account the 3-dimensional complexity of the region as well as the cross-sectional anatomical detail available to today's radiologist. This analytical approach should permit identification of lesional anatomical subsites, establishment of lesional origins, and allow for an anatomy-based differential diagnosis. In this article, we define a practical central skull base region that includes structures that directly affect neuroimaging of this dense landscape. By reframing the boundaries, the central skull base region becomes comprehensive, emphasizing the natural tendency for pathologic processes to involve contiguous anatomical subunits, and underscores the complexity and challenges of this region for neuroimaging specialists.

Endocranial lesions.

Numerous intracranial soft tissue and vascular structures are intimately related to the endocranial surface of the central skull base, including the pituitary gland, the pachymeninges, and multiple cranial nerves. These structures can give rise to pathologies that create imaging abnormalities along the bony surface of the skull base or result in gross changes of the underlying bone: hyperostosis, scalloping, permeation, erosion, or destruction. Large lesions with frank invasion may be difficult to differentiate from intrinsic bone lesions. This article reviews a variety of endocranial lesions affecting the central skull base, including the giant or invasive pituitary macroadenoma and skull base meningioma, and highlights the imaging features for a practical approach to their diagnosis.

Neuroimaging: intrinsic lesions of the central skull base region.

The sphenoid bone is the osseous foundation of the central skull base. The body of the sphenoid is cuboid in shape and its posterior margin is joined to the basilar occipital bone (basiocciput) via a synchondrosis to form the complete clivus. Traditionally, radiologic discussions of intrinsic disease of the central skull base emphasize marrow space-occupying lesions including metastatic disease, myeloma, and chordoma. Based on our practical experience and the anatomical boundaries of the central skull-based region put forth, we include lesions of the sphenoid sinus and petrous apex in our discussion. We describe lesions that might originate within, be confined to, or principally involve the skeletal foundation of the central skull base, including the pneumatized regions contained within. Intrinsic lesions affecting the central skull base are emphasized and the most important computed tomography and magnetic resonance imaging findings that allow for effective diagnosis, planning, and treatment are highlighted.