Faculty Bibliography

BACKGROUND AND PURPOSE/OBJECTIVE:Photon-counting CT (PCCT) offers several advantages over conventional CT for cochlear implant (CI) imaging, including improved spatial resolution, and both signal-to-noise and contrast-to-noise ratios. However, the optimal PCCT reconstruction parameters for CI imaging has not been established. This study compared six PCCT reconstruction approaches for temporal bone CI imaging in a multi-reader design. MATERIALS AND METHODS/METHODS:20 patients with CIs (24 implants) underwent temporal bone PCCT on a NAEOTOM Alpha scanner. Raw data was reconstructed using six different algorithms, as follows: Hr84 0.2mm T3D (head-regular, sharpness level 84, polyenergetic), Hr84 0.4mm T3D, Qr56 0.4mm iMAR T3D (quantitative-regular, sharpness level 56, iterative metal artifact reduction), Qr76 0.4mm M_140 (virtual monoenergetic 140 keV), Qr76 0.4mm M_70 (virtual monoenergetic 70 keV), and Qr76 0.4mm T3D.Two fellowship-trained neuroradiologists independently rated electrode visibility and overall image quality for all implants, and wire visibility for implants with visible wires, on 0-2 Likert scales. Inter-reader agreement was assessed with quadratic weighted Cohen's kappa. A mixed effects model was used to evaluate reconstruction differences for each metric. RESULTS:Mean patient age was 50.9 ± 26 years; 8 were women. Inter-reader agreement was substantial for electrode visibility (κ = 0.66) and overall image quality (κ = 0.79), and moderate for wire visibility (κ = 0.52). Reconstruction type significantly affected all three metrics. The sharp kernel reconstructions (Hr84 0.2mm T3D and Hr84 0.4mm T3D) consistently ranked highest, with significantly greater scores than most other reconstructions. Qr56 0.4mm iMAR T3D was the lowest rated in every category, significantly worse than all other reconstructions. CONCLUSIONS:PCCT reconstruction parameters substantially influence postoperative CI image quality. Ultra-high-resolution reconstructions provided the best combination of artifact suppression and fine structural detail, while iterative MAR and high-keV monoenergetic reconstructions performed the worst. These findings can guide reconstruction selection to optimize PCCT protocols for CI evaluation.

Neoplasms in the temporal bone range from frequently encountered lesions such as vestibular schwannomas, to rare carcinomas. Knowledge of the intricate imaging anatomy of the temporal bone as well as key imaging features of each lesion aids in diagnosis and forming an appropriate differential diagnosis. Advances in imaging and treatment options continue to improve our understanding of these lesions and diagnostic capabilities.

Wolfram syndrome is a neurodegenerative disorder caused by pathogenic variants in the genes WFS1 or CISD2. Clinically, the classic phenotype is composed of optic atrophy, diabetes mellitus type 1, diabetes insipidus, and deafness. Wolfram syndrome, however, is phenotypically heterogenous with variable clinical manifestations and age of onset. We describe four cases of genetically confirmed Wolfram syndrome with variable presentations, including acute-on-chronic vision loss, dyschromatopsia, and tonic pupils. All patients had optic atrophy, only three had diabetes, and none exhibited the classic Wolfram phenotype. MRI revealed a varying degree of the classical features associated with the syndrome, including optic nerve, cerebellar, and brainstem atrophy. The cohort's genotype and presentation supported the reported phenotype-genotype correlations for Wolfram, where missense variants lead to milder, later-onset presentation of the Wolfram syndrome spectrum. When early onset optic atrophy and/or diabetes mellitus are present in a patient, a diagnosis of Wolfram syndrome should be considered, as early diagnosis is crucial for the appropriate referrals and management of the associated conditions. Nevertheless, the condition should also be considered in otherwise unexplained, later-onset optic atrophy, given the phenotypic spectrum.

The persistent carotid-vertebrobasilar anastomoses are arterial communications between the anterior and posterior circulations due to the persistence of embryological connections. We here present an extremely rare instance of a transclival persistent carotid-vertebrobasilar anastomosis in a 10-month-old infant, which does not fit into any of the traditionally described categories, such as the trigeminal artery, hypoglossal artery, or proatlantal artery.

Pre- and postoperative imaging is increasingly used in plastic and reconstructive surgery for the evaluation of bony and soft tissue anatomy. Imaging plays an important role in preoperative planning. In the postoperative setting, imaging is used for the assessment of surgical positioning, bone healing and fusion, and for the assessment of early or delayed surgical complications. This article will focus on imaging performed for surgical reconstruction of the face, including orthognathic surgery, facial feminization procedures for gender dysphoria, and face transplantation.

Background: The base of neck and thoracic inlet is sometimes considered a 'no man's land,' with imaging anatomy shared by both head and neck and thoracic radiologists. Informally, thoracic radiologists may endorse limited confidence with normal anatomy and pathology in this region, which serves as a conduit for several important anatomic structures. Further, thoracic radiologists may not be aware of the clinical impact of some anatomic variants and abnormalities (which may influence patient symptoms or affect surgical planning). Multiple factors contribute to variability in imaging appearances of the lower neck and thoracic inlet, including z-axis scan range and scan angle, patient kyphosis, and arm position. Accurate recognition of normal and variant anatomy is critical to detect pathology and minimize diagnostic error at the lower neck and thoracic inlet on chest computed tomography (CT). Educational Goals/Teaching Points: We aim to provide a systemsbased, image-rich review of normal and variant anatomy and pathology at the lower neck and thoracic inlet, primarily utilizing CT. When appropriate, the clinical relevance of anatomic variants will be discussed. Challenging and often overlooked pathology will be reviewed in an effort to build radiologists' confidence and improve diagnostic accuracy. This will include cross-sectional imaging of a variety of anatomic organs and systems: Upper aerodigestive tract including larynx and hypopharynx Vascular structures, including variant course, vessel thrombus, dissection, and aneurysm Endocrine glands, including ectopic thyroid, thyroglossal duct cyst, and parathyroid adenoma Lymphatics, including relevant nodal stations, and pathology including lymphocele Nervous system structures including brachial plexus, vagus nerve, recurrent laryngeal nerve, and cervical sympathetic trunk Musculoskeletal structures including cervical ribs and supernumerary heads of the sternocleidomastoid muscle
Conclusion(s): By reviewing normal and variant anatomy and clinically relevant pathology at the lower neck and thoracic inlet, thoracic radiologists can achieve greater diagnostic confidence and accuracy

BACKGROUND AND PURPOSE:Accurate differentiation of paragangliomas and schwannomas in the jugular foramen has important clinical implications because treatment strategies may vary but differentiation is not always straightforward with conventional imaging. Our aim was to evaluate the accuracy of both qualitative and quantitative metrics derived from dynamic contrast-enhanced MR imaging using golden-angle radial sparse parallel MR imaging to differentiate paragangliomas and schwannomas in the jugular foramen. MATERIALS AND METHODS:test. A univariate logistic model was created with a binary output, paraganglioma or schwannoma, using a wash-in rate as a variable. Additionally, lesions were clustered on the basis of the wash-in rate and washout rate using a 3-nearest neighbors method. RESULTS:< .001). All 30 lesions were classified correctly by using a 3-nearest neighbors method. CONCLUSIONS:Paragangliomas at the jugular foramen can be reliably differentiated from schwannomas using golden-angle radial sparse parallel MR imaging-dynamic contrast-enhanced imaging when imaging characteristics cannot suffice.

The cavernous sinus is a complex structure susceptible to a wide variety of vascular, neoplastic and inflammatory pathologies. Vascular pathologies include ICA aneurysms, carotid-cavernous fistulas, cavernous sinus thrombosis, and cavernous hemangioma. Neoplasms that involve the cavernous sinus include pituitary adenoma, meningioma, schwannoma, lymphoma, perineural tumor spread, metastases, and direct tumor invasion. Infectious and inflammatory diseases include Tolosa-Hunt syndrome, sarcoidosis, granulomatosis with polyangiitis, IgG-4 related disease and invasive fungal infections. In this article, we review the clinical and imaging findings of a number of pathologies involving the cavernous sinus, focusing on key features that can narrow the differential diagnosis and, in some cases, support a particular diagnosis.

Combining magnetic resonance imaging (MRI) with 2-deoxy-2-F-fluoro-D-glucose positron emission tomography (FDG-PET) data improve the imaging accuracy for detection of Alzheimer disease and related dementias. Integrated FDG-PET-MRI is a recent technical innovation that allows both imaging modalities to be obtained simultaneously from individual patients with cognitive impairment. This report describes the practical benefits and challenges of using integrated FDG-PET-MRI to support the clinical diagnosis of various dementias. Over the past 7 years, we have performed integrated FDG-PET-MRI on >1500 patients with possible cognitive impairment or dementia. The FDG-PET and MRI protocols are the same as current conventions, but are obtained simultaneously over 25 minutes. An additional Dixon MRI sequence with superimposed bone atlas is used to calculate PET attenuation correction. A single radiologist interprets all imaging data and generates 1 report. The most common positive finding is concordant temporoparietal volume loss and FDG hypometabolism that suggests increased risk for underlying Alzheimer disease. Lobar-specific atrophy and FDG hypometabolism patterns that may be subtle, asymmetric, and focal also are more easily recognized using combined FDG-PET and MRI, thereby improving detection of other neurodegeneration conditions such as primary progressive aphasias and frontotemporal degeneration. Integrated PET-MRI has many practical benefits to individual patients, referrers, and interpreting radiologists. The integrated PET-MRI system requires several modifications to standard imaging center workflows, and requires training individual radiologists to interpret both modalities in conjunction. Reading MRI and FDG-PET together increases imaging diagnostic yield for individual patients; however, both modalities have limitations in specificity.

The major salivary glands can be affected by a variety of acute or chronic, systemic, and neoplastic conditions. Several modalities can be used for salivary gland imaging, each with its own advantages and limitations. The article reviews the optimal imaging modality for different clinical scenarios, the typical imaging appearance of commonly encountered pathologies, and seeks to provide a framework for generating an appropriate differential diagnosis. Additionally, with regard to neoplastic conditions, the goals of the review are to highlight features suggestive of benign or low-grade lesions versus high-grade malignancy, while recognizing the limitations of imaging in making specific histologic diagnoses.