COVID-19-associated Diffuse Leukoencephalopathy and Microhemorrhages.

Diffuse leukoencephalopathy and juxtacortical and/or callosal microhemorrhages were brain imaging features in critically ill patients with coronavirus disease 2019. Coronavirus disease 2019 (COVID-19) has been reported in association with a variety of brain imaging findings such as ischemic infarct, hemorrhage, and acute hemorrhagic necrotizing encephalopathy. Herein, the authors report brain imaging features in 11 critically ill patients with COVID-19 with persistently diminished mental status who underwent MRI between April 5 and April 25, 2020. These imaging features include (a) confluent T2 hyperintensity and mild restricted diffusion in bilateral supratentorial deep and subcortical white matter (in 10 of 11 patients) and (b) multiple punctate microhemorrhages in juxtacortical and callosal white matter (in seven of 11 patients). The authors also discuss potential pathogeneses.

Extension of the Thoracic Spine Sign: A New Sonographic Marker of Pleural Effusion.

OBJECTIVES: Dyspnea is a common emergency department (ED) condition, which may be caused by pleural effusion and other thoracic diseases. We present data on a new sonographic marker, the extension of the thoracic spine sign, for diagnosis of pleural effusion. METHODS: In this prospective study, we enrolled a convenience sample of undifferentiated patients who underwent computed tomography (CT) of the abdomen or chest, which was performed as part of their emergency department evaluations. Patients underwent chest sonography to assess the utility of the extension of the thoracic spine sign for diagnosing pleural effusion. The point-of-care sonographic examinations were performed and interpreted by emergency physicians who were blinded to information in the medical records. Sonographic results were compared to radiologists' interpretations of the CT results, which were considered the criterion standard. RESULTS: Forty-one patients were enrolled, accounting for 82 hemithoraces. Seven hemithoraces were excluded from the analysis due to various limitations, leaving 75 hemithoraces for the final analysis. The median time for completion of the sonographic examination was 3 minutes. The sensitivity and specificity for extension of the thoracic spine were 73.7% (95% confidence interval [CI], 48.6%-89.9%) and 92.9% (95%CI, 81.9%-97.7%), respectively. Overall, there were 5 hemithoraces with false-negative results when using the extension sign. Of those 5 cases, 4 were found to have trace pleural effusions on CT. When trace pleural effusions were excluded in a subgroup analysis, the sensitivity and specificity of extension of the thoracic spine were 92.9% (95% CI, 64.2%-99.6%) and 92.9% (95% CI, 81.9%-97.7%). CONCLUSIONS: We found the extension of the thoracic spine sign to be an excellent diagnostic tool for clinically relevant pleural effusion.

Perforated Meckel's diverticulum presenting as a hematocele on scrotal sonography.

Hemorrhage from ectopic gastric mucosa is the most common presenting symptom of Meckel's diverticulum. Diverticular perforation, although rare, is a potentially life-threatening complication. Various imaging modalities can aid in the preoperative detection of Meckel's diverticulum. We report the sonographic findings of a hematocele as the heralding sequela of a perforated Meckel's diverticulum in an 11-month-old boy.

A Worm's Tale or Why to Avoid the Raccoon Latrine: A Case of Baylisascaris procyonis Meningoencephalitis.

The raccoon roundworm Baylisascaris procyonis (B. procyonis) may infect humans to cause severe or fatal meningoencephalitis, as well as ocular and visceral larva migrans. Young children are at greater risk for cerebral larva migrans with severe meningoencephalitis, and early empiric therapy may improve outcomes. Familiarity with characteristic brain imaging findings may prompt earlier diagnosis, particularly in the setting of CSF eosinophilia. We report a case of a 19-month-old boy who presented with truncal ataxia and was found to have peripheral and CSF eosinophilia. MRI demonstrated symmetric, confluent T2 hyperintense signal in the cerebral and cerebellar deep white mater, which helped differentiate B. procyonis meningoencephalitis from other infectious and non-infectious causes of eosinophilic meningoencephalitis. Early recognition and treatment of B. procyonis meningoencephalitis are important for improved outcomes, and careful review of neuroimaging can play a critical role in suggesting the diagnosis.

Vessel wall imaging with advanced flow suppression in the characterization of intracranial aneurysms following flow diversion with Pipeline embolization device.

BACKGROUND: High-resolution vessel wall MRI (VWI) is increasingly used to characterize intramural disorders of the intracranial vasculature unseen by conventional arteriography. OBJECTIVE: To evaluate the use of VWI for surveillance of flow diverter (FD) treated aneurysms. MATERIALS AND METHODS: Retrospective study of 28 aneurysms (in 21 patients) treated with a FD (mean 57 years; 14 female). All examinations included VWI and a contemporaneously obtained digital subtraction angiogram. Multiplanar pre- and post-gadolinium 3D, variable flip-angle T1 black-blood VWI was obtained using delay alternating nutation for tailored excitation (DANTE) at 3T. 3D time-of-flight MR angiography (MRA) was also carried out. Images were assessed for in-stent stenosis, aneurysm occlusion, presence and pattern/distribution of aneurysmal or parent vessel gadolinium enhancement. RESULTS: The VWI-MRI was performed on average at 361±259 days after the intervention. Follow-up DSA was performed at 338±254 days postintervention. Good or excellent black-blood angiographic quality was recorded in 22/28 (79%) pre-contrast and 21/28 (75%) post-contrast VWI, with no cases excluded for image quality. Aneurysm enhancement was noted in 24/28 (85.7%) aneurysms, including in 79% of angiographically occluded aneurysms and 100% of angiographically non-occluded aneurysms. Enhancement of the stented parent-vessel wall occurred significantly more often when aneurysm enhancement was present (92% vs 33%, p=0.049). CONCLUSION: Advanced VWI produces excellent depiction of FD-treated aneurysms, with robust evaluation of the parent vessel and aneurysm wall to an extent not achievable with conventional MRI/MRA. Gadolinium enhancement may, however, continue even after enduring catheter angiographic occlusion, confounding interpretation, and requiring cognizance of this potentially prolonged effect in such patients.

Highly time-resolved 4D MR angiography using golden-angle radial sparse parallel (GRASP) MRI.

Current dynamic MRA techniques are limited by temporal resolution and signal-to-noise penalties. GRASP, a fast and flexible MRI technique combining compressed-sensing, parallel imaging, and golden-angle radial sampling, acquires volumetric data continuously and can be reconstructed post hoc for user-defined applications. We describe a custom pipeline to retrospectively reconstruct ultrahigh temporal resolution, dynamic MRA from GRASP imaging obtained in the course of routine practice. GRASP scans were reconstructed using a custom implementation of the GRASP algorithm and post-processed with MeVisLab (MeVis Medical Solutions AG, Germany). Twenty consecutive examinations were scored by three neuroradiologists for angiographic quality of specific vascular segments and imaging artifacts using a 4-point scale. Unsubtracted images, baseline-subtracted images, and a temporal gradient dataset were available in 2D and 3D reconstructions. Distinct arterial and capillary phases were identified in all reconstructions, with a median of 2 frames (IQR1-3 and 2-3, respectively). Median rating for vascular segments was 3 (excellent) in all reconstructions and for nearly all segments, with excellent intraclass correlation (range 0.91-1.00). No cases were degraded by artifacts. GRASP-MRI obtained in routine practice can be seamlessly repurposed to produce high quality 4D MRA with 1-2-s resolved isotropic cerebrovascular angiography. Further exploration into diagnostic accuracy in disease-specific applications is warranted.

MRI of placenta accreta: a new imaging perspective.

OBJECTIVE: The goal of this study was to identify new MR criteria and review established MR criteria for the diagnosis of placenta accreta. MR images of all patients presenting to our department for evaluation of placenta accreta over the previous 5 years were reviewed and findings were correlated with surgical pathology. CONCLUSION: We found the most sensitive MR criteria for the diagnosis of invasive placentation to be abnormal placental vascularity in addition to the previously described intraplacental T2 dark bands.

Paradoxical Thromboembolic Ischemic Stroke Following Tissue Plasminogen Activator Instillation for Clogged Central Venous Dialysis Catheter.

Central venous catheters including dialysis catheters are a potential source of venous thrombosis and pose a risk for paradoxical embolic events including ischemic stroke and systemic embolism in patients with a patent foramen ovale (PFO). The adult population with a PFO and patients with a central venous dialysis catheter (CVDC) are at increased risk of a paradoxical embolic event. Since bubble study is not routinely done during echocardiogram in a patient with CVDC, it is difficult to identify at-risk patients for paradoxical embolic events during catheter manipulation, especially for clogged CVDC. We report a rare case of a 79-year-old lady with end-stage renal disease on hemodialysis (HD) using a CVDC who developed a paradoxical embolic ischemic stroke following the use of tissue plasminogen activator (tPA) for unclogging a dialysis catheter. We aimed to highlight the existing risks of thromboembolism associated with the long-term use of central CVDC, especially the potential risk of paradoxical embolism and ischemic stroke with the use of tPA for management of clogged dialysis catheters. We emphasize the questionable need for a bubble study echocardiogram in all patients requiring long-term dialysis catheters.

Carotid intimal sarcoma causing stroke and intracranial metastasis via tumor embolization.

OBJECTIVE: To present the clinical, radiologic, and pathologic findings of a patient with carotid intimal sarcoma. METHODS: Detailed medical interview, neurologic examination, and diagnostic evaluation including CT angiography head and neck, MRI brain and neck, digital subtraction angiography, and biopsy of the mass were performed. RESULTS: We report a patient who presented with symptoms of multifocal, bilateral strokes over weeks caused by an enlarging tumor thrombus associated with an intimal sarcoma of the carotid artery. The presence of a carotid space mass encasing the left internal carotid artery was initially not recognized on imaging and was mistakenly attributed to soft atheromatous plaque rather than tumor thrombus. Rapid disease progression resulted in multiple intracranial metastases from tumor embolization. CONCLUSION: Clinical and radiologic findings of intimal sarcoma may be similar to those of thrombotic disease. However, patients with sarcoma may show an associated perivascular soft tissue mass and an unusual distribution of vessel stenosis. Reevaluation of imaging should be considered in patients presenting with initial imaging findings suggestive of rapidly progressive thrombotic disease who have a poor response to antithrombotic therapy and do not follow an expected clinical course.

Endometrioma presenting as a cavitary lung mass with intense 18F-FDG uptake on PET-CT.

[18F]-fluoro-2-deoxy-D-glucose positron emission tomography computed tomography is a useful tool to suggest the diagnosis of malignant processes. However, false positive results are known to occur in benign lesions that have a high metabolic activity. Here we describe the unusual diagnosis of a pulmonary endometrioma in a 47-year-old woman, presenting as a cavitary lung mass with intense (18)F-FDG uptake on PET-CT.

Phase II study of everolimus in children and adults with neurofibromatosis type 2 and progressive vestibular schwannomas.

BACKGROUND: Activation of the mammalian target of rapamycin (mTOR) signaling pathway is thought to be a key driver of tumor growth in Merlin (NF2)-deficient tumors. Everolimus is an oral inhibitor of mTOR complex 1 (mTORC1) with antitumor activity in a variety of cancers. METHODS: We conducted a single-institution, prospective, 2-stage, open-label phase II study to estimate the response rate to everolimus in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Ten eligible patients were enrolled, including 2 pediatric patients. Everolimus was administered at a daily dose of 10 mg (adults) or 5 mg/m(2)/day (children <18 y) orally in continuous 28-day courses, for up to 12 courses. Response was assessed every 3 months with MRI, using 3-dimensional volumetric tumor analysis, and audiograms. Nine patients were evaluable for the primary response, defined as ≥15% decrease in VS volume. Hearing response was evaluable as a secondary endpoint in 8 patients. RESULTS: None of the 9 patients with evaluable disease experienced a clinical or MRI response. No objective imaging or hearing responses were observed in stage 1 of the trial, and the study was closed according to predefined stopping rules. CONCLUSION: Everolimus is ineffective for the treatment of progressive VS in NF2 patients. We are currently conducting a pharmacokinetic/pharmacodynamic ("phase 0") study of everolimus in presurgical VS patients to elucidate the biological basis for apparent treatment resistance to mTORC1 inhibition in these tumors.