Philip R. Chapman

Imaging manifestations of progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by reactivation of JC virus in immunosuppressed patients. The diagnosis is usually suggested on imaging and confirmed by cerebrospinal fluid polymerase chain reaction (PCR) for JC virus DNA. In this article, we review the imaging manifestations of PML on computed tomography (CT), magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), MR spectroscopy, single photon-emission computed tomography (SPECT) and positron-emission tomography (PET), and outline the role of imaging in follow-up and prognostication.

Petrous Apex Lesions: Pictorial Review

Received January 19, 2010; accepted after revision August 4, 2010. 1Department of Radiology, Division of Neuroradiology, University of Alabama at Birmingham Medical Center, 619 19th St S, WP-150, Birmingham, AL 35249-6830. Address correspondence to A. K. Bag (abag@uabmc.edu). 2Present address: Department of Radiology, Edward Hines Jr VA Hospital, Hines, IL. AJR 2011; 196:WS26–WS37 0361–803X/11/1963–WS1

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.

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.

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, Kendalls coefficient of concordance (W), and interclass correlation coefficient (ICC) were applied to determine interrater reliability. For intrarater reliability analysis, Cohens kappa (κ), Kendalls 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 (Kendalls 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 (Kendalls 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 (Kendalls 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 todays 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.

Vascular Lesions of the Central Skull Base Region

The arterial and venous structures of the central skull base region form complex anatomical relationships with each other and with adjacent osseous and neural structures. Vascular structures including the cavernous sinuses and internal carotid arteries can be displaced, encased, or invaded by neoplastic, inflammatory, or infectious lesions of the central skull base. Consequently, the vascular structures have a unique role in determining the imaging appearance, clinical significance, and therapeutic options of lesions occurring in the central skull base. This article briefly reviews the basic anatomy of the cavernous sinus and the relationship of the internal carotid artery to the cavernous sinus and central skull base. The major imaging features of some common vascular lesions, including skull base aneurysm, carotid-cavernous fistula, and cavernous sinus thrombosis are presented.

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.

Primary CNS Nonamyloidogenic Light Chain Deposition Disease: Case Report and Brief Review:

The true incidence of light chain deposition disease (LCDD) restricted to the central nervous system (CNS) is unknown. To our knowledge only 7 cases of LCDD restricted to the brain have been previously reported. We herein describe an unusual example. A 44-year-old man presented with a history of ischemic retinopathy in 2004 and left lower extremity hypoesthesia in 2007 that progressed gradually to left-sided weakness and numbness in the 2 years prior to his hospitalization in 2015. A stereotactic brain biopsy was performed, displaying nonspecific hyaline deposits of amorphous “amyloid-like” material involving deep brain white matter and vessels. These were Congo red negative and were accompanied by a sparse lymphoplasmacytic infiltrate. Plasma cells demonstrated kappa light chain class restriction by chromogenic in situ hybridization (CISH). There was patchy reactivity with kappa immunohistochemistry in the amorphous deposits. A diagnosis of light chain deposition disease was made. Subsequent systemic myeloma and lymphoma workups were negative. Previously reported cases have included men and women, spanning the ages of 19 and 72 years, often presenting with hemiparesis, hypoesthesia, or seizures. Deposits have been reported in the cerebrum and cerebellum. T2/FLAIR (fluid attenuation inversion recovery) changes are usual, but lesions may or may not produce contrast enhancement. The light chain deposition may be of kappa or lambda class. Most lesions have been accompanied by local lymphoid and/or plasma cell infiltrates exhibiting light chain restriction of the same class as the deposits. In summary, LCDD limited to the CNS is a rare lesion consisting of deposition of amyloid-like, but Congo red–negative monotypic light chain usually produced by local lymphoplasmacytic infiltrates.

Complex Cerebellopontine Angle Mass in a Patient With a History of Falls

Awoman in her 50s presented to the emergency department after a fall. She reported being clumsy her entire life, thoughwithworsening difficulty with balance over the past few years. She occasionally had falls, which were sometimes preceded by vertigo and “shaking” episodes. A contrast-enhanced temporal bone computed tomographic (CT) scan was performed. An axial image through the level of the temporal bones demonstrated a mixed-density mass within the right cerebellopontine angle (CPA) causing mass effect on the pons and cerebellum (Figure, A). The lateral soft-tissue density component of the mass extended through a widened porus acusticus and into the internal auditory canal (Figure, B), without bony destruction. No calcifications were identified. The medial component of the lesion demonstrated lower density, appearing at first to represent fluid or cystic change. Closer inspection, however, revealed negative Hounsfield units, indicating the presence of fat. Subsequent magnetic resonance imaging (MRI) demonstrated an unusual extra-axial CPA mass with multiple complex signals. A T1-weighted MRI scan demonstrated expected T1 hyperintensity within the medial component, confirming the presence of fat (Figure, B). The lateral component, at the porus acusticus, was isointense, without flow voids. T2-weighted images demonstrated additional complexity of signal with inhomogeneous signal in both the fat and the soft-tissue components (Figure, C). Postcontrast axial fat-saturated T1-weighted images (Figure, D) demonstrated nodular enhancement of the soft-tissue component and expected fat saturation of the medial component. Because of the mass’s effect on the brainstem, the mass was resected. What is your diagnosis? A B