The Spectrum of Neuroimaging Findings on CT and MRI in Adults With COVID-19.

Neurologic involvement is well-recognized in COVID-19. This article reviews the neuroimaging manifestations of COVID-19 on CT and MRI, presenting cases from the New York City metropolitan region encountered by the authors during the first surge of the pandemic. The most common neuroimaging manifestations are acute infarcts with large clot burden and intracranial hemorrhage, including microhemorrhages. However, a wide range of additional imaging patterns occur, including leukoencephalopathy, global hypoxic injury, acute disseminated encephalomyelitis, cytotoxic lesions of the corpus callosum, olfactory bulb involvement, cranial nerve enhancement, and Guillain-Barré syndrome. The described CNS abnormalities largely represent secondary involvement from immune activation that leads to a prothrombotic state and cytokine storm; evidence for direct neuroinvasion is scant. Comorbidities such as hypertension, complications of prolonged illness and hospitalization, and associated supportive treatments also contribute to the CNS involvement in COVID-19. Routine long-term neurologic follow-up may be warranted, given emerging evidence of long-term microstructural and functional changes on brain imaging after COVID-19 recovery.

Arterial spin labeling for head and neck lesion assessment: technical adjustments and clinical applications.

PURPOSE: Despite, currently, "state-of-the-art" magnetic resonance imaging (MRI) protocols for head and neck (H&N) lesion assessment incorporate perfusion sequences, these acquisitions require the intravenous injection of exogenous gadolinium-based contrast agents (GBCAs), which may have potential risks. Alternative techniques such as arterial spin labeling (ASL) can provide quantitative microvascular information similar to conventional perfusion sequences for H&N lesions evaluation, as a potential alternative without GBCA administration. METHODS: We review the existing literature and analyze the latest evidence regarding ASL in H&N area highlighting the technical adjustments needed for a proper ASL acquisition in this challenging region for lesion characterization, treatment monitoring, and tumor recurrence detection. RESULTS: ASL techniques, widely used for central nervous system lesions evaluation, can be also applied to the H&N region. Technical adjustments, especially regarding post-labeling delay, are mandatory to obtain robust and reproducible results. Several studies have demonstrated the feasibility of ASL in the H&N area including the orbits, skull base, paranasal sinuses, upper airway, salivary glands, and thyroid. CONCLUSION: ASL is a feasible technique for the assessment of H&N lesions without the need of GBCAs. This manuscript reviews ASL's physical basis, emphasizing the technical adjustments necessary for proper ASL acquisition in this unique and challenging anatomical region, and the main applications in evaluating H&N lesions.

The early effect of COVID-19 on dental infections by neuroimaging in the emergency department setting.

OBJECTIVES: In early 2020, at COVID-19's onset in the United States, the American Dental Association recommended postponing elective dental procedures to minimize viral spread. Subsequently, concerns arose that this could result in increased dental infections and resultant emergency department visits. This study quantifies the number and severity of dental infections at the onset of the early COVID-19 outbreak in early 2020 in the Northeast United States resulting in emergency room visits and radiographic imaging compared to 2017-2019 with an analysis of geographic population characteristics. METHODS: Cross-sectional head and neck imaging performed at an East Coast hospital system was retrospectively reviewed for dental infections from March 2020 through December 2020, and compared to prior years 2017-2019. Inclusion criteria included radiology reporting of a dental infection, ranging in severity. Electronic medical records (EMR) and imaging reports were queried for patient characteristics and dental findings. RESULTS: There were 735 confirmed imaging reports of odontogenic infections. There was a significant increase in imaging reporting of odontogenic infections in the post-shutdown period. These were more frequently early-type infections, involved a higher proportion of male and non-white patients, and the patients were more often from disadvantaged zip codes when compared with prior years. CONCLUSIONS: These findings highlight the varying impact of outpatient dental office closures on different socioeconomic groups in the setting of a pandemic. Potential implications include increased morbidity and mortality for patients, as well as increased cost and resource allocations for the healthcare system.

Semi-automated Segmentation and Quantification of Perivascular Spaces at 7 Tesla in COVID-19.

While COVID-19 is primarily considered a respiratory disease, it has been shown to affect the central nervous system. Mounting evidence shows that COVID-19 is associated with neurological complications as well as effects thought to be related to neuroinflammatory processes. Due to the novelty of COVID-19, there is a need to better understand the possible long-term effects it may have on patients, particularly linkage to neuroinflammatory processes. Perivascular spaces (PVS) are small fluid-filled spaces in the brain that appear on MRI scans near blood vessels and are believed to play a role in modulation of the immune response, leukocyte trafficking, and glymphatic drainage. Some studies have suggested that increased number or presence of PVS could be considered a marker of increased blood-brain barrier permeability or dysfunction and may be involved in or precede cascades leading to neuroinflammatory processes. Due to their size, PVS are better detected on MRI at ultrahigh magnetic field strengths such as 7 Tesla, with improved sensitivity and resolution to quantify both concentration and size. As such, the objective of this prospective study was to leverage a semi-automated detection tool to identify and quantify differences in perivascular spaces between a group of 10 COVID-19 patients and a similar subset of controls to determine whether PVS might be biomarkers of COVID-19-mediated neuroinflammation. Results demonstrate a detectable difference in neuroinflammatory measures in the patient group compared to controls. PVS count and white matter volume were significantly different in the patient group compared to controls, yet there was no significant association between PVS count and symptom measures. Our findings suggest that the PVS count may be a viable marker for neuroinflammation in COVID-19, and other diseases which may be linked to neuroinflammatory processes.

Imaging of Sella and Parasellar Region.

The sellar and parasellar region is complex, with a unique meningeal, neural, vascular, and bony anatomy. Understanding the imaging anatomy is critical for accurate imaging interpretation. resonance (MR) imaging is the primary modality for pituitary imaging, whereas computed tomography may be used when MR imaging is contraindicated, and provides complementary bony anatomic information. This article reviews embryology and anatomy of the sellar and parasellar region. Imaging appearances of pituitary adenomas, Rathke cleft cysts, meningiomas, craniopharyngiomas, arachnoid cysts, vascular disorders, infectious abnormalities, and pituitary apoplexy are discussed and illustrated.

Unique Imaging Findings of Neurologic Phantosmia Following Pfizer-BioNtech COVID-19 Vaccination: A Case Report.

ABSTRACT: Olfactory dysfunction related to SARS-CoV-2 infection and COVID-19 disease is now well established in the literature. In December 2020, the FDA approved the Pfizer-BioNTech and Moderna vaccines for use in preventing COVID-19 in the United States. To the best of our knowledge, this is the first report of a phantosmia post-Pfizer COVID-19 vaccination, with positive magnetic resonance imaging radiographic findings in a patient with documented absence of infection by SARS-CoV-2 virus or concomitant sinonasal disease.

Special MRI Techniques to Suss out Spontaneous Cerebrospinal Fluid Leaks.

ABSTRACT: Anterior skull base cerebrospinal fluid (CSF) fistulas result from skull base osteodural defects, allowing subarachnoid space CSF to escape into pneumatized cavities such as the paranasal sinuses and nasal fossa. Precise localization, characterization, and effective treatment of CSF leaks is essential to prevent meningitis, treatment failure, or recurrence. Advances in magnetic resonance imaging have improved radiologists' ability to localize and characterize anterior skull base CSF fistulas. This article reviews new imaging techniques enabling diagnostic location of CSF fistulas, with an emphasis on magnetic resonance imaging-based techniques.

The anatomy of nasopharyngeal carcinoma spread through the pharyngobasilar fascia to the trigeminal mandibular nerve on 1.5 T MRI.

PURPOSE: To analyze, from 1.5 Tesla (T) MRI clinical cases, anatomical accessibility of nasopharyngeal tumors through the pharyngobasilar fascia (PBF) to the mandibular nerve for potential perineural spread. METHODS: A 6-year retrospective review of 1.5 T MR images were rated for tumor involvement of fascial planes and perineural spread in 15 consecutive patients (10 female, 5 male; mean age 45.8 years, range 19-86) with histopathologically proven tumors of the nasopharynx and referrals for radiotherapy due to intracranial extension. RESULTS: Nasopharyngeal tumors were best appreciated on T1 fat-saturated, post-gadolinium MRI. Tumors extended through the sinus of Morgagni in all cases. This sinus is a defect in the PBF through which the Eustachian tube and levator veli palatini muscle gain access to the nasopharynx. In six patients, the PBF and tensor veli palatini fascia were breached anteriorly with tumor infiltration of the tensor veli palatini and medial pterygoid muscles. In 13 cases, tumor breached the posterolateral PBF with extension into the poststyloid parapharyngeal space. In three subjects, 3 T images were also acquired and exhibited superior delineation of the anatomy and perineural tumor spread. CONCLUSIONS: At 1.5 T, images showed nasopharyngeal tumors extending through the PBF into the masticator and parapharyngeal spaces, with access to the mandibular nerve and potential for perineural spread. At 3 T, soft tissue resolution appeared superior to 1.5 T. This may reflect not only the increased field strength, but an improved technique and matrix, and future studies are necessary to confirm this observation. Awareness of this anatomy for radiation and surgical planning is essential and may improve the ability for obtaining negative margins, and increasing overall survival.

The human temporalis muscle: superficial, deep, and zygomatic parts comprise one structural unit.

The structure of the temporalis muscle was examined in detail from cadaveric specimens (32 specimens from 16 subjects: 5 males, average age 80.6 years; 11 females, average age 88.6 years) and Computerized Tomography (CT) and T1-weighted Magnetic Resonance (MR) images from normal clinical patients (10 females: average age 45.0 years). Three parts of the muscle were clearly delineated in all cadaveric specimens: (1) the classically recognized superficial part, (2) a zygomatic part, and (3) a complex deep part. In one female specimen, the superficial temporalis demonstrated extensive insertions into the zygomatic process and temporomandibular joint. The zygomatic temporalis originates from the zygomatic arch to insert into the superficial part of the temporalis as it inserts into the lateral surface of the coronoid process. In all specimens, the deep temporalis contained muscle bundles that originated from various crests along the anterior surface of the temporal fossa and inserted into the internal aspect of the coronoid process and retromolar triangle, interdigitating with the buccinator, mylohyoid, and superior constrictor muscles. The confluence of muscle fibers into the buccinator muscle was confirmed in all CT/MRI images. The deep and zygomatic parts described were regarded as accessory muscle bellies previously, but are demonstrably part of the temporalis muscle as a whole.

Headache Caused by Sinus Disease.

Headaches and sinus disease are common reasons to seek medical care, with marked worldwide prevalence and large socioeconomic burdens. Headaches caused by sinus diseases are rare; many "rhinogenic headaches" are actually migraines. The similar symptoms may result from autonomic dysfunction and trigeminovascular pathways. Using the mnemonic ACHE, this article presents key Anatomy, Clinical cases, How to image, Essential clinical and radiographic features that help the radiologist, otolaryngologist, and neurologist evaluate sinus disease and headaches.

ACR Appropriateness Criteria® Neck Mass-Adenopathy.

A palpable neck mass may be the result of neoplastic, congenital, or inflammatory disease. Older age suggests neoplasia, and a congenital etiology is more prevalent in the pediatric population. The imaging approach is based on the patient age, mass location, and clinical pulsatility. Underlying human papillomavirus-related malignancy should be considered in all age groups. Although the imaging appearance of some processes in the head and neck overlap, choosing the appropriate imaging examination may allow a specific diagnosis, or a limited differential diagnosis. Tissue sampling is indicated to confirm suspected malignancy. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Suspected Spine Trauma.

Injuries to the cervical and thoracolumbar spine are commonly encountered in trauma patients presenting for treatment. Cervical spine injuries occur in 3% to 4% and thoracolumbar fractures in 4% to 7% of blunt trauma patients presenting to the emergency department. Clear, validated criteria exist for screening the cervical spine in blunt trauma. Screening criteria for cervical vascular injury and thoracolumbar spine injury have less validation and widespread acceptance compared with cervical spine screening. No validated criteria exist for screening of neurologic injuries in the setting of spine trauma. CT is preferred to radiographs for initial assessment of spine trauma. CT angiography and MR angiography are both acceptable in assessment for cervical vascular injury. MRI is preferred to CT myelography for assessing neurologic injury in the setting of spine trauma. MRI is usually appropriate when there is concern for ligament injury or in screening obtunded patients for cervical spine instability. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Acute Mental Status Change, Delirium, and New Onset Psychosis.

Acute changes in mental status represent a broad collection of symptoms used to describe disorders in mentation and level of arousal, including the more narrowly defined diagnoses of delirium and psychosis. A wide range of precipitating factors may be responsible for symptom onset including infection, intoxication, and metabolic disorders. Neurologic causes that may be detected on neuroimaging include stroke, traumatic brain injury, nonconvulsive seizure, central nervous system infection, tumors, hydrocephalus, and inflammatory disorders. Not infrequently, two or more precipitating factors may be found. Neuroimaging with CT or MRI is usually appropriate if the clinical suspicion for an acute neurological cause is high, where the cause of symptoms is not found on initial assessment, and for patients whose symptoms do not respond appropriately to management. There was disagreement regarding the appropriateness of neuroimaging in cases where a suspected, nonneurologic cause is found on initial assessment. Neuroimaging with CT is usually appropriate for patients presenting with delirium, although the yield may be low in the absence of trauma or a focal neurological deficit. Neuroimaging with CT or MRI may be appropriate in the evaluation of new onset psychosis, although the yield may be low in the absence of a neurologic deficit. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Cervical Neck Pain or Cervical Radiculopathy.

Nontraumatic neck pain is a leading cause of disability, with nearly 50% of individuals experiencing ongoing or recurrent symptoms. Radiographs are appropriate as initial imaging for cervical or neck pain in the absence of "red flag" symptoms or if there are unchanging chronic symptoms; however, spondylotic changes are commonly identified and may result in both false-positive and false-negative findings. Noncontrast CT can be complementary to radiographs for evaluation of new or changing symptoms in the setting of prior cervical spine surgery or in the assessment of extent of ossification in the posterior longitudinal ligament. Noncontrast MRI is usually appropriate for assessment of new or increasing radiculopathy due to improved nerve root definition. MRI without and with contrast is usually appropriate in patients with new or increasing cervical or neck pain or radiculopathy in the setting of suspected infection or known malignancy. Imaging may be appropriate; however, it is not always indicated for evaluation of cervicogenic headache without neurologic deficit. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Practical Tips for MR Imaging of Perineural Tumor Spread.

Perineural tumor spread (PNS) substantially alters a patient's prognosis and treatment plan. Therefore, it is critical that the radiologists are familiar with the course of cranial nerves commonly affected by PNS and the neuronal connections to appropriately map the extent of PNS. Limited involvement of a nerve by PNS might be resectable, whereas advanced PNS may require radiation therapy.

ACR Appropriateness Criteria® Hearing Loss and/or Vertigo.

This article presents guidelines for imaging utilization in patients presenting with hearing loss or vertigo, symptoms that sometimes occur concurrently due to proximity of receptors and neural pathways responsible for hearing and balance. These guidelines take into account the superiority of CT in providing bony details and better soft-tissue resolution offered by MRI. It should be noted that a dedicated temporal bone CT rather than a head CT best achieves delineation of disease in many of these patients. Similarly, optimal assessment often requires a dedicated high-resolution protocol designed to assess temporal bone and internal auditory canals even though such a study will be requested and billed as a brain MRI. Angiographic techniques are helpful in some patients, especially in the setting of vertigo. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Management of Vertebral Compression Fractures.

Vertebral compression fractures (VCFs) have various causes, including osteoporosis, neoplasms, and acute trauma. As painful VCFs may contribute to general physical deconditioning, management of painful VCFs has the potential for improving quality of life and preventing superimposed medical complications. Various imaging modalities can be used to evaluate a VCF to help determine the etiology and guide intervention. The first-line treatment of painful VCFs has been nonoperative or conservative management as most VCFs show gradual improvement in pain over 2 to 12 weeks, with variable return of function. There is evidence that vertebral augmentation (VA) is associated with better pain relief and improved functional outcomes compared to conservative therapy for osteoporotic VCFs. A multidisciplinary approach is necessary for the management of painful pathologic VCFs, with management strategies including medications to affect bone turnover, radiation therapy, and interventions such as VA and percutaneous thermal ablation to alleviate symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diplopia: What to Double Check in Radiographic Imaging of Double Vision.

When patients see double with both eyes open, known as "binocular diplopia," this may be a harbinger of underlying life-threatening causes. This article presents pertinent anatomy, critical abnormality, and radiographic features that should be double checked for in diplopia. Key areas requiring a double check using the acronym VISION include Vascular, Infectious and Inflammatory, the Scalp for giant cell arteritis, Sphenoid and Skull base in trauma, Increased intracranial pressure (pseudotumor cerebri), Onset of new headaches or psychosis, and Neoplasm. This article reviews the pertinent abnormalities and radiographic imaging critical to assess in patients with diplopia.