Faculty Bibliography

Various anatomic structures and variants in the temporal bone are potential radiological mimics and surgical hazards. The imaging features of normal variants and lesions with similar imaging appearance are presented in this article. Throughout the article, salient features that can help elucidate the distinguishing features between mimics and imaging pitfalls are presented.

The anatomy of the skull base is complex and poses a daunting challenge to many radiologists and trainees. In addition to knowing major skull base passages, there are several underrecognized skull base canals, foramina, and fissures that are critical to avoid misdiagnosis, understand the spread of disease, and guide surgical management. A review of the current literature on these forgotten structures yielded numerous original articles and a few review articles, none of which were comprehensive. This article aimed to fill that void. We provide a comprehensive review of underrecognized skull base anatomic structures and their content and discuss their clinical implications. Learning Objective: Recognize uncommon skull base structures, their content, and their clinical implications.

Hyperparathyroidism is defined as excessive parathyroid hormone production. The diagnosis is made through biochemical testing, in which imaging has no role. However, imaging is appropriate for preoperative parathyroid gland localization with the intent of surgical cure. Imaging is particularly useful in the setting of primary hyperparathyroidism whereby accurate localization of a single parathyroid adenoma can facilitate minimally invasive parathyroidectomy. Imaging can also be useful to localize ectopic or supernumerary parathyroid glands and detail anatomy, which may impact surgery. This document summarizes the literature and provides imaging recommendations for hyperparathyroidism including primary hyperparathyroidism, recurrent or persistent primary hyperparathyroidism after parathyroid surgery, secondary hyperparathyroidism, and tertiary hyperparathyroidism. Recommendations include ultrasound, CT neck without and with contrast, and nuclear medicine parathyroid scans. 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.

Even though teeth are often included in the field of view for a variety of medical CT studies, dental pathology is often missed by radiologists. Given the myriad morbidity and occasional mortality associated with sequelae of dental pathology, an important goal is to decrease these false negatives. However, given the ever-increasing volume of cases studies that radiologists have to read and the number of structures and diseases they have to evaluate, it is important not to place undue time restraints on the radiologist to this end. We hypothesized that generating panoramic dental radiographs from non-dental CT scans can permit identification of key diseases, while not adding much time to interpretation. The key advantage of panoramic dental radiographs is that they display the plane of the teeth in two dimensions, thereby facilitating fast and accurate assessment. We found that interpreting panoramic radiographic reconstructions compared to the full CT volumes reduced time-to-diagnosis of key dental pathology on average by roughly a factor of four. This expedition was statistically significant, and the average time-to-diagnosis for panoramic reconstructions was on the order of seconds, without a loss in accuracy compared to full CT. As such, we posit that panoramic reconstruction can serve as a one-slice additional series in any CT image stack that includes the teeth in its field of view.

OBJECTIVE:To describe a case of bilateral sudden sensorineural hearing loss (SSNHL) and intralabyrinthine hemorrhage in a patient with COVID-19. STUDY DESIGN:Clinical capsule report. SETTING:Tertiary academic referral center. PATIENT:An adult woman with bilateral SSNHL, aural fullness, and vertigo with documented SARS-CoV-2 infection (IgG serology testing). INTERVENTIONS:High-dose oral prednisone with taper, intratympanic dexamethasone. MAIN OUTCOME MEASURES:Audiometric testing, MRI of the internal auditory canal with and without contrast. RESULTS:A patient presented with bilateral SSNHL, bilateral aural fullness, and vertigo. Serology testing performed several weeks after onset of symptoms was positive for IgG COVID-19 antibodies. MRI showed bilateral intralabyrinthine hemorrhage (left worse than right) and no tumor. The patient was treated with two courses of high-dose oral prednisone with taper and a left intratympanic dexamethasone injection, resulting in near-resolution of vestibular symptoms, a fluctuating sensorineural hearing loss in the right ear, and a severe to profound mixed hearing loss in the left ear. CONCLUSIONS:COVID-19 may have otologic manifestations including sudden SSNHL, aural fullness, vertigo, and intralabyrinthine hemorrhage.

Purpose/UNASSIGNED:To report a case of neurovascular compression in a patient presenting with ophthalmic evidence of aberrant reinnervation. Observation/UNASSIGNED:A 68-year-old woman diagnosed with right partial third nerve palsy with aberrant regeneration. Suspicion was based on isolated clinical features of the right eye, including ptosis, upper eyelid elevation on adduction, mydriasis, exotropia, and hypotropia. Magnetic resonance imaging revealed atrophy of the right oculomotor nerve secondary to neurovascular compression from a prominent right superior cerebellar artery. Conclusion and importance/UNASSIGNED:This case highlights the importance of utilizing Fast Imaging Employing Steady-state Acquisition (FIESTA) for the diagnosis of oculomotor nerve palsy presenting with evidence of aberrant reinnervation.

BACKGROUND/UNASSIGNED:Acute neurological sequela in patients with COVID-19 infection include acute thromboembolic infarcts related to cytokine storm and post infectious immune activation resulting in a prothrombotic state. Radiologic imaging studies of the sinonasal tract and mastoid cavity in patients with COVID-19 infection are sparse and limited to case series. In this report, we investigate the radiologic involvement of nasal cavity, nasopharynx, paranasal sinuses, and mastoid cavity in patients with SARS-CoV-2 infection who presented with acute neurological symptoms. METHODS/UNASSIGNED:Retrospective review of medical records and neuroradiologic imaging in patients diagnosed with acute COVID-19 infection who presented with acute neurological symptoms to assess radiologic prevalence of sinus and mastoid disease and its correlation to upper respiratory tract symptoms. RESULTS/UNASSIGNED:Of the 55 patients, 23 (42%) had partial sinus opacification, with no evidence for complete sinus opacification. The ethmoid sinus was the most commonly affected (16/55 or 29%). An air fluid level was noted in 6/55 (11%) patients, most commonly in the maxillary sinus. Olfactory recess and mastoid opacification were uncommon. There was no evidence of bony destruction in any of the studies, Cough, nasal congestion, rhinorrhea, and sore throat were not significantly associated with any radiological findings. CONCLUSION/UNASSIGNED:In patients who present with acute neurological symptoms, COVID-19 infection is characterized by limited and mild mucosal disease within the sinuses, nasopharynx and mastoid cavity. LEVEL OF EVIDENCE/UNASSIGNED:4.

Many patients with SARS-CoV-2 infection develop neurological signs and symptoms, though, to date, little evidence exists that primary infection of the brain is a significant contributing factor. We present the clinical, neuropathological, and molecular findings of 41 consecutive patients with SARS-CoV-2 infections who died and underwent autopsy in our medical center. The mean age was 74 years (38-97 years), 27 patients (66%) were male and 34 (83%) were of Hispanic/Latinx ethnicity. Twenty-four patients (59%) were admitted to the intensive care unit (ICU). Hospital-associated complications were common, including 8 (20%) with deep vein thrombosis/pulmonary embolism (DVT/PE), 7 (17%) patients with acute kidney injury requiring dialysis, and 10 (24%) with positive blood cultures during admission. Eight (20%) patients died within 24 hours of hospital admission, while 11 (27%) died more than 4 weeks after hospital admission. Neuropathological examination of 20-30 areas from each brain revealed hypoxic/ischemic changes in all brains, both global and focal; large and small infarcts, many of which appeared hemorrhagic; and microglial activation with microglial nodules accompanied by neuronophagia, most prominently in the brainstem. We observed sparse T lymphocyte accumulation in either perivascular regions or in the brain parenchyma. Many brains contained atherosclerosis of large arteries and arteriolosclerosis, though none had evidence of vasculitis. Eighteen (44%) contained pathologies of neurodegenerative diseases, not unexpected given the age range of our patients. We examined multiple fresh frozen and fixed tissues from 28 brains for the presence of viral RNA and protein, using quantitative reverse-transcriptase PCR (qRT-PCR), RNAscope, and immunocytochemistry with primers, probes, and antibodies directed against the spike and nucleocapsid regions. qRT-PCR revealed low to very low, but detectable, viral RNA levels in the majority of brains, although they were far lower than those in nasal epithelia. RNAscope and immunocytochemistry failed to detect viral RNA or protein in brains. Our findings indicate that the levels of detectable virus in COVID-19 brains are very low and do not correlate with the histopathological alterations. These findings suggest that microglial activation, microglial nodules and neuronophagia, observed in the majority of brains, do not result from direct viral infection of brain parenchyma, but rather likely from systemic inflammation, perhaps with synergistic contribution from hypoxia/ischemia. Further studies are needed to define whether these pathologies, if present in patients who survive COVID-19, might contribute to chronic neurological problems.

A posterior skull base lesion is an uncommon radiological finding that may be noted incidentally or during targeted imaging of patients with clinical symptoms attributable to the lesion. It may be inflammatory or neoplastic in etiology, or may simply be an anatomic variant or a "don't-touch" lesion that should not be misinterpreted as something more ominous. A systematic approach to the evaluation of the posterior skull base is therefore required in order to differentiate lesions requiring immediate attention from those requiring a less urgent course of action or none at all. This review will focus on the imaging features of pathologic conditions that are more commonly encountered in posterior skull base CT and MR examinations.