Long-term Efficacy of Single-agent Vemurafenib for Pleomorphic Xanthoastrocytoma.

Pleomorphic xanthoastrocytoma is a malignant brain tumor that has a good prognosis with complete resection but does not respond well to chemotherapy if there is residual tumor. BRAF V600E mutations are common in pleomorphic xanthoastrocytomas and provide an additional means for treatment when excision is not possible. Monotherapy with the BRAF V600E inhibitor vemurafenib has only been reported in a small number of cases and mostly in adults. We present the case of a 16-year-old male who responded to vemurafenib monotherapy initially and had an additional response to vemurafenib following progression after a brief time off the medication.

MRI surveillance following concurrent cochlear implantation in cases of vestibular schwannoma resection.

OBJECTIVE: Cochlear nerve preserving translabyrinthine vestibular schwannoma (VS) resection enables concurrent cochlear implantation. Implantation in patients with VS raises important concerns including the ability to undergo postoperative magnetic resonance imaging (MRI) monitoring of residual tumor growth or tumor recurrence, specifically with a retained magnet. We aim to assess the feasibility of MRI monitoring and the impact on image quality with retained cochlear implant (CI) magnets. METHODS: Retrospective review of post-operative head MRI scans in CI recipients with a retained CI magnet, after cochlear nerve preserving translabyrinthine excision of VS. The ability to visualize the ipsilateral and contralateral internal auditory canal (IAC) and cerebellopontine angle (CPA) were assessed. RESULTS: A total of eight surveillance head MRI were performed in six patients. In one case, in which the receiver was positioned lower, the view of the ipsilateral IAC and CPA was distorted. In all other cases, the views of both the ipsilateral and contralateral IAC and CPA were overall unimpaired. DISCUSSION: Imaging artifact only very rarely impedes adequate visualization of the ipsilateral IAC or CPA in CI recipients. In anticipation of the need for further IAC and CPA imaging, it would be advisable to place the receiver in an exaggerated superior-posterior position to further decrease obscuring artifact. Thus, serial monitoring of VS tumors can be performed safely with preservation of image quality with a retained receiver magnet. CONCLUSIONS: When placing the CI receiver-stimulator farther posterior-superiorly, excellent visualization of the IAC and CPA can be accomplished without significantly impairing the image quality.

Performance of acoustic radiation force impulse ultrasound imaging for carotid plaque characterization with histologic validation.

OBJECTIVE: Stroke is commonly caused by thromboembolic events originating from ruptured carotid plaque with vulnerable composition. This study assessed the performance of acoustic radiation force impulse (ARFI) imaging, a noninvasive ultrasound elasticity imaging method, for delineating the composition of human carotid plaque in vivo with histologic validation. METHODS: Carotid ARFI images were captured before surgery in 25 patients undergoing clinically indicated carotid endarterectomy. The surgical specimens were histologically processed with sectioning matched to the ultrasound imaging plane. Three radiologists, blinded to histology, evaluated parametric images of ARFI-induced peak displacement to identify plaque features such as necrotic core (NC), intraplaque hemorrhage (IPH), collagen (COL), calcium (CAL), and fibrous cap (FC) thickness. Reader performance was measured against the histologic standard using receiver operating characteristic curve analysis, linear regression, Spearman correlation (ρ), and Bland-Altman analysis. RESULTS: ARFI peak displacement was two-to-four-times larger in regions of NC and IPH relative to regions of COL or CAL. Readers detected soft plaque features (NC/IPH) with a median area under the curve of 0.887 (range, 0.867-0.924) and stiff plaque features (COL/CAL) with median area under the curve of 0.859 (range, 0.771-0.929). FC thickness measurements of two of the three readers correlated with histology (reader 1: R2 = 0.64, ρ = 0.81; reader 2: R2 = 0.89, ρ = 0.75). CONCLUSIONS: This study suggests that ARFI is capable of distinguishing soft from stiff atherosclerotic plaque components and delineating FC thickness.

Does CISS MRI Reliably Depict the Endolymphatic Duct in Children with and without Vestibular Aqueduct Enlargement?

BACKGROUND AND PURPOSE: High-resolution CT is the mainstay for diagnosing an enlarged vestibular aqueduct (EVA), but MR imaging may be an appealing alternative, given its lack of ionizing radiation exposure. The purpose of this study was to determine how reliably MR imaging demonstrates the endolymphatic duct and endolymphatic duct enlargement in hearing-impaired children. MATERIALS AND METHODS: We performed a retrospective review of temporal bone high-resolution CT and MR imaging of hearing-impaired children evaluated between 2017 and 2020. Vestibular aqueduct diameter was measured on high-resolution CT. The vestibular aqueducts were categorized as being enlarged (EVA+) or nonenlarged (EVA-) using the Cincinnati criteria. The endolymphatic ducts were assessed on axial high-resolution CISS MR imaging. We categorized endolymphatic duct visibility into the following: type 1 (not visible), type 2 (faintly visible), and type 3 (easily visible). Mixed-effect logistic regression was used to identify associations between endolymphatic duct visibility and EVA. Interreader agreement for the endolymphatic duct among 3 independent readers was assessed using the Fleiss κ statistic. RESULTS: In 196 ears from 98 children, endolymphatic duct visibility on MR imaging was type 1 in 74.0%, type 2 in 14.8%, and type 3 in 11.2%; 20.4% of ears were EVA+ on high-resolution CT. There was a significant association between EVA+ status and endolymphatic duct visibility (P < .01). Endolymphatic duct visibility was type 1 in 87.1%, type 2 in 12.8%, and type 3 in 0% of EVA- ears and type 1 in 22.5%, type 2 in 22.5%, and type 3 in 55.0% of EVA+ ears. The predicted probability of a type 3 endolymphatic duct being EVA+ was 0.997. There was almost perfect agreement among the 3 readers for distinguishing type 3 from type 1 or 2 endolymphatic ducts. CONCLUSIONS: CISS MR imaging substantially underdiagnoses EVA; however, when a type 3 endolymphatic duct is evident, there is a >99% likelihood of an EVA.

Osseointegration and Bone Resorption of Scapula Tip Free Flaps in Mandibular Reconstruction.

OBJECTIVES: Bone resorption of more conventional vascularized bone grafts have been well described showing minimal resorption over time. Few studies have evaluated osseous union and bone resorption in scapula tip free flaps (STFF) in the reconstruction of mandibulectomy defects. We aimed to describe our series on STFF with respect to osseous union and bone resorption over time. METHODS: Retrospective chart review of patients receiving STFF from January 2014-January 2017 (n = 25). A neuroradiologist analyzed follow-up CT scans to assess (1) STFF complete, partial, or no osseous union with native mandible and (2) STFF volume change over time in a subset with multiple follow-up scans (n = 18). RESULTS: Twenty-three of 25 patients (92%) showed complete or partial STFF osseous union with native mandible either distally or proximally. STFF volume change ranged from +4.8 to -54% (median -0.5%) over median follow-up interval of 23 months. History of chemoradiation therapy, bisphophonate use, sex, age, or smoking history did not correlate with bone resorption. CONCLUSIONS: STFFs shows high rates of osseous union and limited bone resorption that is equivalent to, or less than, vascularized fibular and iliac crest flaps. Clinically, this translates into both optimal healing and functional and cosmetic outcomes, especially in the setting of prior therapies. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2597-2602, 2023.

Lesions of the petrous apex: classification and findings at CT and MR imaging.

The petrous apex is a complex region of the central skull base that is surrounded by a number of important vascular and neural structures and can be home to a wide range of disease processes. Lesions arising in or spreading to the petrous apex cause varied and occasionally severe clinical sequelae, which typically result from mass effect or direct invasion of the cranial nerves, brainstem, or internal carotid artery. Because the petrous apex is not amenable to direct examination, cross-sectional imaging with computed tomography and magnetic resonance (MR) imaging plays an important role in diagnosis and characterization of lesions occurring there. Petrous apex lesions can be classified on the basis of their origin into the following categories: developmental lesions, inflammatory lesions, benign tumors, malignant tumors, vascular lesions, and osseous dysplasias. The most common lesions arising in the petrous apex are cholesterol granulomas, which can be reliably diagnosed with MR imaging due to their high signal intensity on both T1-weighted images and T2-weighted images. In addition, one should also be familiar with anatomic variants or pseudolesions in the petrous apex that can be mistaken for pathologic conditions.

Anatomy of the Larynx and Cervical Trachea.

The larynx serves as the gateway between the upper and lower respiratory tracts and is involved in the tasks of phonation, deglutition, and airway protection. Familiarity with the complex anatomy of the larynx is critical for detecting and characterizing disease in the region, especially in cancer staging. In this article, we review the anatomy of the larynx and cervical trachea, including an overview of their cartilages, supporting tissues, muscles, mucosal spaces, neurovascular supply, and lymphatics, followed by correlation to the clinically relevant anatomic sites of the larynx. Imaging techniques for evaluating the larynx and trachea will also be discussed briefly.

Update on MR Imaging of Soft Tissue Tumors of Head and Neck.

This article reviews soft tissue tumors of the head and neck following the 2020 revision of WHO Classification of Soft Tissue and Bone Tumours. Common soft tissue tumors in the head and neck and tumors are discussed, along with newly added entities to the classification system. Salient clinical and imaging features that may allow for improved diagnostic accuracy or to narrow the imaging differential diagnosis are covered. Advanced imaging techniques are discussed, with a focus on diffusion-weighted and dynamic contrast imaging and their potential to help characterize soft tissue tumors and aid in distinguishing malignant from benign tumors.

Soft tissue tumors of the head and neck: imaging-based review of the WHO classification.

The World Health Organization (WHO) system for defining and classifying soft tissue tumors is usually applied to lesions that occur in the trunk and extremities, but it also provides an excellent framework for characterizing nonepithelial extraskeletal tumors of the head and neck. Although nonepithelial extraskeletal tumors are in the minority among head and neck lesions, they are by no means rare. The WHO classification system recognizes nine major types based on histologic differentiation: adipocytic, fibroblastic or myofibroblastic, fibrohistiocytic, smooth muscle, skeletal muscle, vascular, pericytic, and chondro-osseous tumors, as well as soft tissue tumors of uncertain differentiation. Tumors of each histologic type may be further subclassified on the basis of their biologic behavior as benign, intermediate (ie, having malignant potential), or malignant. Imaging plays an important role in the noninvasive diagnosis and characterization of nonepithelial soft tissue tumors of the head and neck, providing clues about tumor grade, composition, extent, and involvement of adjacent structures. Although the imaging characteristics of many such tumors are nonspecific, consideration of the clinical history in concert with the imaging findings may help limit the differential diagnosis or even allow reliable diagnosis of some of these tumors.

Failed endoscopic sinus surgery: spectrum of CT findings in the frontal recess.

Since its introduction over 2 decades ago, functional endoscopic sinus surgery (FESS) has revolutionized the surgical management of chronic sinusitis. Performed over 200,000 times annually in the United States to treat medically refractory sinusitis, FESS has success rates as high as 98%. When surgical failure occurs, it is typically due to postoperative scarring or unaddressed outflow tract obstruction in the region of the frontal recess. The most common causes of surgical failure in the frontal recess include remnant frontal recess cells, a retained uncinate process, middle turbinate lateralization, osteoneogenesis, scarring or inflammatory mucosal thickening, and recurrent polyposis. Computed tomography (CT) of the paranasal sinuses has become indispensable in evaluation of patients with FESS failure, particularly in the frontal recess, a location that can be difficult to visualize at endoscopy. Familiarity with the complex anatomy of the frontal recess and knowledge of the most common causes of surgical failure are essential for proper interpretation of sinus CT images obtained in patients being considered for revision FESS of the frontal sinus.

Radiographic muscle invasion not a recurrence predictor in HPV-associated oropharyngeal squamous cell carcinoma.

OBJECTIVE: To determine whether muscle invasion evident on pretreatment imaging in p16 + oropharyngeal squamous cell carcinoma (OPSCC) correlates with recurrence. STUDY DESIGN: Retrospective review. METHODS: Two-hundred and seventy-six patients with p16 + OPSCC treated at a tertiary referral center from 2003 to 2015 were analyzed. All scans were reviewed by a dedicated neuroradiologist with subspecialty expertise in head and neck imaging. Radiographic evidence of muscle invasion to the genioglossus, hyoglossus, medial pterygoid, and prevertebral muscles was analyzed. Local and regional recurrence rates were compared between the muscle invasion and no muscle invasion groups. RESULTS: One hundred and ninety patients met inclusion criteria with adequate follow-up data and pretreatment imaging. Patients were predominantly male (87.5% male) and smokers (65.6% smokers) with a mean age of 56.7 (standard deviation: 9.0 years). Most commonly invaded muscles in the muscle invasion group were hyoglossus (57.8%) and genioglossus (56.3%). There was no statistically significant difference in primary site or nodal recurrence between the combined group, including definite or possible muscle invasion and the group without muscle invasion (P = 0.205 and P = 0.569, respectively). Additionally, no statistically significant difference was present in recurrence-free and disease-specific survival between the two groups at 3- and 5-year follow-up (P > 0.05). CONCLUSION: Radiographic evidence of muscle invasion does not appear to be a predictor of human papilloma virus (+) OPSCC recurrence. Additional studies are needed to validate our findings. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:871-876, 2019.

Delineation of Human Carotid Plaque Features In Vivo by Exploiting Displacement Variance.

While in vivo acoustic radiation force impulse (ARFI)-induced peak displacement (PD) has been demonstrated to have high sensitivity and specificity for differentiating soft from stiff plaque components in patients with carotid plaque, the parameter exhibits poorer performance for distinguishing between plaque features with similar stiffness. To improve discrimination of carotid plaque features relative to PD, we hypothesize that signal correlation and signal-to-noise ratio (SNR) can be combined, outright or via displacement variance. Plaque feature detection by displacement variance, evaluated as the decadic logarithm of the variance of acceleration and termed "log(VoA)," was compared to that achieved by exploiting SNR, cross correlation coefficient, and ARFI-induced PD outcome metrics. Parametric images were rendered for 25 patients undergoing carotid endarterectomy, with spatially matched histology confirming plaque composition and structure. On average, across all plaques, log(VoA) was the only outcome metric with values that statistically differed between regions of lipid-rich necrotic core (LRNC), intraplaque hemorrhage (IPH), collagen (COL), and calcium (CAL). Further, log(VoA) achieved the highest contrast-to-noise ratio (CNR) for discriminating between LRNC and IPH, COL and CAL, and grouped soft (LRNC and IPH) and stiff (COL and CAL) plaque components. More specifically, relative to the previously demonstrated ARFI PD parameter, log(VoA) achieved 73% higher CNR between LRNC and IPH and 59% higher CNR between COL and CAL. These results suggest that log(VoA) enhances the differentiation of LRNC, IPH, COL, and CAL in human carotid plaques, in vivo, which is clinically relevant to improving stroke risk prediction and medical management.

Hypoxic-ischemic brain injury: imaging findings from birth to adulthood.

Global hypoxic-ischemic injury (HII) to the brain is a significant cause of mortality and severe neurologic disability. Imaging plays an important role in the diagnosis and treatment of HII, helping guide case management in the acute setting and providing valuable information about long-term prognosis. Appropriate radiologic diagnosis of HII requires familiarity with the many imaging manifestations of this injury. Factors such as brain maturity, duration and severity of insult, and type and timing of imaging studies all influence findings in HII. Severe hypoxia-ischemia in both preterm and term neonates preferentially damages the deep gray matter, with perirolandic involvement more frequently observed in the latter age group. Less profound insults result in intraventricular hemorrhages and periventricular white matter injury in preterm neonates and parasagittal watershed territory infarcts in term neonates. In the postnatal period, severe insults result in diffuse gray matter injury, with relative sparing of the perirolandic cortex and the structures supplied by the posterior circulation. Profound hypoxia-ischemia in older children and adults affects the deep gray matter nuclei, cortices, hippocampi, and cerebellum. Because findings at conventional imaging may be subtle or even absent in the acute setting, particularly in neonates, magnetic resonance spectroscopy can help establish the diagnosis of HII. Promising new neuroprotective strategies designed to limit the extent of brain injury caused by hypoxia-ischemia are currently under investigation.

Image quality and dose reduction in sinus computed tomography using iterative reconstruction: a cadaver study.

BACKGROUND: Concerns about radiation dose in computed tomography (CT) imaging have renewed interest in iterative reconstruction (IR), a technique which has the potential to produce images with less noise at lower radiation doses than traditional filtered back projection (FBP). This study aimed to assess whether application of IR could provide comparable quality sinus CT images to FBP at lower kilovolt (kV) and milliamp (mA) settings, and to establish optimal scan settings for sinus imaging. METHODOLOGY/PRINCIPAL: 30 sinus CT scans were performed on 5 cadaver heads at two kV setting and three mA settings. Each scan was reconstructed using FBP and 3 IR settings, yielding a total of 120 images series. Each image set was blinded and randomly reviewed by 3 rhinologists and 2 neuroradiologists. Using a 5-point Likert scale, 16 anatomical landmarks, were graded with respect to image quality. Data were assessed with respect to dose and IR settings using statistical analysis. RESULTS: Higher kV and mAs settings produced significantly higher quality images for structure identification across all 16 landmarks; however, the suitability for surgery did not increase in a linear fashion and plateaued by a total radiation dose of 0.1201 mSv. IR algorithm did not provide a benefit in the overall score of scans at a fixed kV and mAs. CONCLUSIONS: Identification of structures in sinus CT imaging significantly correlate with the kV and mA and overall dose of radiation; however, IR did not provide additional benefit in the image quality.

Radiological reasoning: extracranial causes of unilateral decreased brain perfusion.

OBJECTIVE: A 50-year-old man presented with neurologic symptoms and upper extremity claudication associated with exercise. Perfusion MRI of the brain showed delayed time-to-peak in the right cerebral hemisphere, and MR angiography (MRA) of the circle of Willis showed decreased flow-related enhancement in the right internal carotid artery and its branches. Neck MRA showed occlusion of the right innominate (brachiocephalic) artery and retrograde flow in the ipsilateral vertebral artery. On the basis of this clinical scenario, we discuss the radiologic evaluation of unilateral decreased brain perfusion, which, in this case, was due to an occlusion of the innominate artery with resultant innominate steal. CONCLUSION: In the absence of an explanatory intracranial stenosis, the finding of unilateral decreased cerebral perfusion on MRI or CT mandates evaluation of the aortic arch and cervical arteries to determine a level and cause of occlusion. Severe stenoses may be associated with steal phenomena, which can be diagnosed with MRA or Doppler sonography.

Evaluation of PET/MRI for Tumor Volume Delineation for Head and Neck Cancer.

INTRODUCTION: Computed tomography (CT), combined positron emitted tomography and CT (PET/CT), and magnetic resonance imaging (MRI) are commonly used in head and neck radiation planning. Hybrid PET/MRI has garnered attention for potential added value in cancer staging and treatment planning. Herein, we compare PET/MRI vs. planning CT for head and neck cancer gross tumor volume (GTV) delineation. MATERIAL AND METHODS: We prospectively enrolled patients with head and neck cancer treated with definitive chemoradiation to 60-70 Gy using IMRT. We performed pretreatment contrast-enhanced planning CT and gadolinium-enhanced PET/MRI. Primary and nodal volumes were delineated on planning CT (GTV-CT) prospectively before treatment and PET/MRI (GTV-PET/MRI) retrospectively after treatment. GTV-PET/MRI was compared to GTV-CT using separate rigid registrations for each tumor volume. The Dice similarity coefficient (DSC) metric evaluating spatial overlap and modified Hausdorff distance (mHD) evaluating mean orthogonal distance difference were calculated. Minimum dose to 95% of GTVs (D95) was compared. RESULTS: Eleven patients were evaluable (10 oropharynx, 1 larynx). Nine patients had evaluable primary tumor GTVs and seven patients had evaluable nodal GTVs. Mean primary GTV-CT and GTV-PET/MRI size were 13.2 and 14.3 cc, with mean intersection 8.7 cc, DSC 0.63, and mHD 1.6 mm. D95 was 65.3 Gy for primary GTV-CT vs. 65.2 Gy for primary GTV-PET/MRI. Mean nodal GTV-CT and GTV-PET/MRI size were 19.0 and 23.0 cc, with mean intersection 14.4 cc, DSC 0.69, and mHD 2.3 mm. D95 was 62.3 Gy for both nodal GTV-CT and GTV-PET/MRI. CONCLUSION: In this series of patients with head and neck (primarily oropharynx) cancer, PET/MRI and CT-GTVs had similar volumes (though there were individual cases with larger differences) with overall small discrepancies in spatial overlap, small mean orthogonal distance differences, and similar radiation doses.

Imaging in Endoscopic Cranial Skull Base and Pituitary Surgery.

Endoscopic endonasal approaches have widely accepted techniques for managing benign and malignant processes along the entire ventral skull base with similar or better results compared with open procedures, but with lower rates of complication. Managing pathology affecting the skull base can be challenging because of complex anatomy and the proximity of critical neurovascular structures. Postoperative imaging can be challenging, because of surgical alterations of normal anatomy and the now common use of complex reconstruction techniques. Understanding the normal imaging appearance of skull base reconstruction is important for accurate postoperative interpretation and delineation between normal reconstructive tissue and recurrent neoplasm.

Does residual wall size or technique matter in the treatment of Zenker's diverticulum?

OBJECTIVES/HYPOTHESIS: We aimed to compare three surgical techniques (open approach for diverticulectomy with cricopharyngeal myotomy [OA], endoscopic laser-assisted diverticulotomy [ELD], and endoscopic stapler-assisted diverticulotomy [ESD]) for treatment of Zenker's diverticulum with regard to validated swallowing outcomes, radiographic outcomes, complications, and revision rates. We statistically analyzed whether the size of residual postoperative party wall or the specific surgical technique correlates with swallowing outcomes. STUDY DESIGN: Retrospective chart review and radiographic study analysis. METHODS: A retrospective chart review and radiographic analysis of preoperative and postoperative contrast swallow studies were conducted on patients undergoing surgery for Zenker's diverticulum between 2002 and 2014 at our institution. A follow-up validated swallowing outcome questionnaire, the Eating Assessment Tool-10, was administered to measure and compare patients' symptomatic outcomes. RESULTS: Seventy-three patients were reviewed and grouped according to technique. Median follow-up was 1.6 years. ESD resulted in a significantly larger residual party wall than ELD and OA but yielded comparative swallowing outcomes. OA had the highest complication rate and ESD had the highest revision rate. There were no revisions after ELD nor OA. CONCLUSIONS: Despite the predictably larger residual postoperative party wall following ESD, this technique produced statistically comparable swallowing outcomes. Given its low complication rate and comparable results, ESD should be considered first line therapy for medically high-risk patients with Zenker's diverticulum, while acknowledging a higher risk of symptom recurrence. ELD, with its slightly greater risk profile but low recurrence rate, is well suited for most in revision cases. OA may best be reserved for those patients in whom endoscopic approach is not feasible. LEVEL OF EVIDENCE: 4 Laryngoscope, 126:2475-2479, 2016.

Nonadenomatous tumors of the pituitary and sella turcica.

While pituitary adenomas make up over 90% of all sellar masses, there are a number of less known tumors, both malignant and benign, which may arise within the sella turcica. These include relatively common tumors such as meningiomas and craniopharyngiomas, as well as extremely rare tumors such as pituitary astrocytomas and granular cell tumors. Unfortunately, many of these tumors lack characteristic imaging features, often making it extremely difficult to distinguish them by imaging alone from the more common pituitary adenoma. In this article, we review several nonadenomatous tumors of the sella, with a focus on their clinical features and typical MR imaging characteristics.

Current Trends in Sinonasal Imaging.

As endoscopic sinus surgery (ESS) has evolved since its introduction to the United States, so has technology for imaging the sinonasal cavities. Although imaging is most frequently performed for evaluating chronic sinusitis refractory to medical therapy, its uses have expanded beyond inflammatory sinus disease. Multidetector Computed Tomography is the current workhorse for both diagnosis and preoperative planning in prospective ESS patients, while MR imaging remains a complementary tool for evaluating suspected tumors or intracranial and orbital complications of rhinosinusitis. In this article, the authors review current trends and potential future directions in the use of these modalities for sinus imaging.