Long-term neuroimaging follow-up of COVID-19-related leukoencephalopathy.

More than a year after the start of the COVID-19 pandemic, long-term neurological manifestations of COVID-19 are increasingly being reported. The long-term sequelae of COVID-19-related leukoencephalopathy, however, remain unclear. Here, we present long-term neuroimaging follow-up in two cases of COVID-19-related leukoencephalopathy. The two cases demonstrate the utility of brain MRI for evaluating neurologic symptoms in critically ill patients with COVID-19, for diagnosis of underlying neural injury and prognostication of future recovery. The presence of leukoencephalopathy may result in chronic neurologic manifestations and may represent a poor prognosticator of neurologic recovery. The presence of leukoencephalomalacia on follow-up neuroimaging is potentially an indicator of irreversible white matter damage, which may be associated with more severe chronic deficits.

Lung apical findings in coronavirus disease (COVID-19) infection on neck and cervical spine CT.

PURPOSE: To evaluate the prevalence and features of lung apical findings on neck and cervical spine CTs performed in patients with COVID-19. METHODS: This was a retrospective, IRB-approved study performed at a large academic hospital in the USA. Between March 3, 2020, and May 6, 2020, 641 patients with COVID-19 infection diagnosed by RT-PCR received medical care at our institution. A small cohort of patients with COVID-19 infection underwent neck or cervical spine CT imaging for indications including stroke, trauma, and neck pain. The lung apices included in the field of view on these CT scans were reviewed for the presence of findings suspicious for COVID-19 pneumonia, including ground-glass opacities, consolidation, or crazy-paving pattern. The type and frequency of these findings were recorded and correlated with clinical information including age, gender, and symptoms. RESULTS: Thirty-four patients had neck or spine CTs performed before or concurrently with a chest CT. Of this group, 17 (50%) had unknown COVID-19 status at the time of neck or spine imaging and 10 (59%) of their CT studies had findings in the lung apices consistent with COVID-19 pneumonia. CONCLUSION: Lung apical findings on cervical spine or neck CTs consistent with COVID-19 infection are common and may be encountered on neuroimaging performed for non-respiratory indications. For these patients, the emergency radiologist may be the first physician to suspect underlying COVID-19 infection.

An imaging review of the hippocampus and its common pathologies.

The hippocampus is a complex structure located in the mesial temporal lobe that plays a critical role in cognitive and memory-related processes. The hippocampal formation consists of the dentate gyrus, hippocampus proper, and subiculum, and its importance in the neural circuitry makes it a key anatomic structure to evaluate in neuroimaging studies. Advancements in imaging techniques now allow detailed assessment of hippocampus internal architecture and signal features that has improved identification and characterization of hippocampal abnormalities. This review aims to summarize the neuroimaging features of the hippocampus and its common pathologies. It provides an overview of the hippocampal anatomy on magnetic resonance imaging and discusses how various imaging techniques can be used to assess the hippocampus. The review explores neuroimaging findings related to hippocampal variants (incomplete hippocampal inversion, sulcal remnant and choroidal fissure cysts), and pathologies of neoplastic (astrocytoma and glioma, ganglioglioma, dysembryoplastic neuroepithelial tumor, multinodular and vacuolating neuronal tumor, and metastasis), epileptic (mesial temporal sclerosis and focal cortical dysplasia), neurodegenerative (Alzheimer's disease, progressive primary aphasia, and frontotemporal dementia), infectious (Herpes simplex virus and limbic encephalitis), vascular (ischemic stroke, arteriovenous malformation, and cerebral cavernous malformations), and toxic-metabolic (transient global amnesia and opioid-associated amnestic syndrome) etiologies.

Incorporating algorithmic uncertainty into a clinical machine deep learning algorithm for urgent head CTs.

Machine learning (ML) algorithms to detect critical findings on head CTs may expedite patient management. Most ML algorithms for diagnostic imaging analysis utilize dichotomous classifications to determine whether a specific abnormality is present. However, imaging findings may be indeterminate, and algorithmic inferences may have substantial uncertainty. We incorporated awareness of uncertainty into an ML algorithm that detects intracranial hemorrhage or other urgent intracranial abnormalities and evaluated prospectively identified, 1000 consecutive noncontrast head CTs assigned to Emergency Department Neuroradiology for interpretation. The algorithm classified the scans into high (IC+) and low (IC-) probabilities for intracranial hemorrhage or other urgent abnormalities. All other cases were designated as No Prediction (NP) by the algorithm. The positive predictive value for IC+ cases (N = 103) was 0.91 (CI: 0.84-0.96), and the negative predictive value for IC- cases (N = 729) was 0.94 (0.91-0.96). Admission, neurosurgical intervention, and 30-day mortality rates for IC+ was 75% (63-84), 35% (24-47), and 10% (4-20), compared to 43% (40-47), 4% (3-6), and 3% (2-5) for IC-. There were 168 NP cases, of which 32% had intracranial hemorrhage or other urgent abnormalities, 31% had artifacts and postoperative changes, and 29% had no abnormalities. An ML algorithm incorporating uncertainty classified most head CTs into clinically relevant groups with high predictive values and may help accelerate the management of patients with intracranial hemorrhage or other urgent intracranial abnormalities.

Interrater Reliability of National Institutes of Health Traumatic Brain Injury Imaging Common Data Elements for Brain Magnetic Resonance Imaging in Mild Traumatic Brain Injury.

The National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH-NINDS) Traumatic Brain Injury (TBI) Imaging Common Data Elements (CDEs) are standardized definitions for pathological intracranial lesions based on their appearance on neuroimaging studies. The NIH-NINDS TBI Imaging CDEs were designed to be as consistent as possible with the U.S. Food and Drug Administration (FDA) definition of biomarkers as "an indicator of normal biological processes, pathogenic processes, or biological responses to an exposure or intervention." However, the FDA qualification process for biomarkers requires proof of reliable biomarker test measurements. We determined the interrater reliability of TBI Imaging CDEs on subacute brain magnetic resonance imaging (MRI) performed on 517 mild TBI patients presenting to 11 U.S. level 1 trauma centers. Three U.S. board-certified neuroradiologists independently evaluated brain MRI performed 2 weeks post-injury for the following CDEs: traumatic axonal injury (TAI), diffuse axonal injury (DAI), and brain contusion. We found very high interrater agreement for brain contusion, with prevalence- and bias-adjusted kappa (PABAK) values for pairs of readers from 0.92 [95% confidence interval, 0.88-0.95] to 0.94 [0.90-0.96]. We found intermediate agreement for TAI and DAI, with PABAK values of 0.74-0.78 [0.70-0.82]. The near-perfect agreement for subacute brain contusion is likely attributable to the high conspicuity and distinctive appearance of these lesions on T1-weighted images. Interrater agreement for TAI and DAI was lower, because signal void in small vascular structures, and artifactual foci of signal void, can be difficult to distinguish from the punctate round or linear areas of slight hemorrhage that are a common hallmark of TAI/DAI on MRI.

Medical Student Education Roadblock Due to COVID-19: Virtual Radiology Core Clerkship to the Rescue.

RATIONALE AND OBJECTIVES: Medical schools were upended by the COVID-19 pandemic, resulting in suspension of all in-person educational activities, and leaving clinical clerkships on hold indefinitely. A virtual curriculum and novel teaching methods were needed to fulfill curricular requirements. We developed a comprehensive virtual radiology clerkship and evaluated the efficacy of this novel method of teaching. MATERIALS AND METHODS: A 4-week virtual radiology clerkship was designed to accommodate medical students who had not yet completed the required clerkship. The design included online flipped classroom modules, large group didactic lectures, and small group homeroom activities. Student performance was assessed via a standardized online final exam. Feedback from students was collected using online surveys. Student performance was compared to the in-person radiology clerkship. RESULTS: One hundred and eleven medical students were enrolled in the virtual radiology clerkship. Final exam scores were similar to the in-person clerkship. Students indicated that small group homeroom activities had the highest overall satisfaction. Students recognized enthusiastic teachers regardless of class format. Exceptional course content and organization were also noted. Course weaknesses included didactic lecture content which was repetitive or too advanced, the limited opportunity to build personal connections with faculty, and scheduling conflicts with other competing school activities. CONCLUSION: A completely virtual radiology core clerkship can be a successful educational experience for medical students during a time when remote learning is required. A small group learning environment is most successful for student engagement. Personal connections between faculty and students can be challenging in a virtual course.

Efficacy of Alectinib in Patients with ALK-Positive NSCLC and Symptomatic or Large CNS Metastases.

BACKGROUND: Central nervous system (CNS) metastases represent a significant source of morbidity and mortality for patients with ALK tyrosine kinase gene (ALK)-positive NSCLC. Alectinib has demonstrated robust CNS activity in both crizotinib-naive and crizotinib-resistant settings. However, the CNS efficacy of alectinib has not been established in patients with untreated symptomatic, large CNS metastases. METHODS: In this retrospective study, patients were eligible if they had advanced ALK-positive NSCLC with large (defined as ≥1 cm) or symptomatic CNS metastases and received alectinib. Medical records and radiographic imaging were reviewed to determine treatment outcomes. CNS efficacy was assessed per the modified Response Evaluation Criteria in Solid Tumors version 1.1. RESULTS: Of the 19 patients, 15 (79%) had measurable CNS disease at baseline and were evaluable for response. The CNS objective response rate in these patients was 73.3% (95% confidence interval [CI]: 44.9%-92.2%), the CNS disease control rate was 100.0% (95% CI: 78.2%-100.0%), and the median CNS duration of response was 19.3 months (95% CI: 14.3 months-not evaluable). In 18 evaluable patients with measurable and/or nonmeasurable baseline CNS disease, the CNS objective response rate was 72.2% (95% CI: 46.5%-90.3%), the CNS disease control rate was 100.0% (95% CI: 81.5%-100.0%), and the median CNS duration of response was 17.1 months (95% CI: 14.3 months-not evaluable). All eight patients with symptoms attributable to CNS metastases had clinical improvement upon starting alectinib therapy. Six patients (32%) eventually required salvage brain radiotherapy. CONCLUSIONS: Alectinib demonstrated meaningful CNS efficacy in patients with ALK-positive NSCLC with untreated symptomatic or large brain metastases.

The Use of Magnetic Resonance Spectroscopy in the Evaluation of Pediatric Patients With Seizures.

BACKGROUND: The objective was to determine if it is useful to routinely add magnetic resonance spectroscopy (MRS) to magnetic resonance imaging (MRI) in the evaluation of seizure in the pediatric patient. Specifically, how often does MRS contribute information to conventional MRI? METHODS: A retrospective search, over a period of 3 years, of patients <18 years of age who underwent both MRI and MRS as part of the evaluation of seizures yielded a total of 233 cases in 216 patients. The medical records were reviewed to determine how many patients carried a diagnosis relevant to seizures. The MRIs and MRSs were reviewed by two neuroradiologists and an MR physicist/spectroscopist who determined by consensus in how many cases MRS contributed information regarding management, diagnosis, or prognosis, in addition to the findings on MRI alone. RESULTS: In 100 of 233 cases (43%), MRS contributed information additional to MRI. In 40 cases, MRS contributed information relevant to patient management by prompting an evaluation for an underlying inborn error of metabolism. MRS contributed information relevant to diagnosis in 24 of 100 cases (e.g., neoplasm versus dysplasia). MRS contributed information relevant to prognosis in 36 cases (e.g., hypoxic-ischemic injury). MRS added more information in cases where the patients had a diagnosis relevant to seizure before imaging. Interestingly, in 25 cases where the MRI was normal, MRS was found to be abnormal, which prompted evaluation for an inborn error of metabolism. CONCLUSIONS: These results suggest that MRS is a useful evaluation tool in addition to MRI for children undergoing imaging for the evaluation of seizures.

Odontogenic orbital inflammation: clinical and CT findings--initial observations.

PURPOSE: To retrospectively review computed tomographic (CT) and clinical findings in patients with odontogenic orbital infection. MATERIALS AND METHODS: Approval from the institutional review board was obtained for chart and scan review, and informed consent was waived for this HIPAA-compliant study. Five patients, two male and three female (median age, 37 years; age range, 13-55 years), who had odontogenic orbital cellulitis underwent clinical evaluation, CT scanning, and treatment. CT findings, including periapical lucency suggesting abscess, sinus opacification, and the route of spread of infection, were analyzed in each patient. Imaging, clinical, and surgical findings, including the initial clinical diagnosis and the presence of a periapical abscess at surgery and at pathologic examination, were compared. RESULTS: Periapical lucency and sinus opacification were seen in all patients. The route of infection spread was through either the premalar soft tissues or the maxillary sinuses. The odontogenic origin of the orbital infection was not clinically suspected in any patients. Correct diagnosis was later made at CT in all patients. Four patients had periapical abscesses at pathologic analysis, and the fifth patient had apical periodontitis at clinical analysis and granuloma at pathologic analysis. Dental surgery was required in each of the five patients for resolution of infection; four patients underwent extraction of the infected tooth, and one patient underwent incision and drainage of a periapical abscess. CONCLUSION: Abnormal periapical lucency, widening of the periodontal ligament space, and the presence of a subperiosteal abscess suggested an odontogenic origin of orbital infection.