Principles and Applications of Dual Energy Computed Tomography in Neuroradiology.

Dual-energy computed tomography (DE CT) is a promising tool with many current and evolving applications. Available DE CT scanners usually consist of one or two tubes, or use layered detectors for spectral separation. Most DE CT scanners can be used in single energy or dual-energy mode, except for the layered detector scanners that always acquire data in dual-energy mode. However, the layered detector scanners can retrospectively integrate the data from two layers to obtain conventional single energy images. DE CT mode enables generation of virtual monochromatic images, blended images, iodine quantification, improving conspicuity of iodinated contrast enhancement, and material decomposition maps or more sophisticated quantitative analysis not possible with conventional SE CT acquisition with an acceptable or even lower dose than the SE CT. This article reviews the basic principles of dual-energy CT and highlights many of its clinical applications in the evaluation of neurological conditions.

Circumferential segmental vessel-wall enhancement on black blood MRI in patients referred for the evaluation of vasculopathy.

BACKGROUND: High resolution intracranial vessel wall magnetic resonance imaging, or black blood MRI, has recently gained traction as an adjunct to computed tomography angiography, magnetic resonance angiography, and digital subtraction angiography in the characterization of atherosclerosis, vasculitides, and inflammatory changes in the aneurysm wall. However, the occurrence of uniform circumferential segmental arterial vessel wall enhancement (CSWE) in patients without these diagnoses has not previously been studied. The purpose of this study is twofold: 1) to evaluate the prevalence of CSWE in the major intracranial arteries in patients without vasculitides, symptomatic atherosclerosis, or aneurysmal subarachnoid hemorrhage and 2) to determine the association, if any, between such enhancement and risk factors for cerebrovascular atherosclerotic disease. MATERIALS & METHODS: A retrospective study of vessel wall magnetic resonance imaging examinations was performed to evaluate for CSWE in 26 patients without known vessel wall pathology such as aneurysms or vasculitides and intracranial hemorrhage. Further evaluation of CSWE association with major intracranial atherosclerotic disease risk factors including hypertension, hyperlipidemia, diabetes mellitus and cigarette smoking was performed. RESULTS AND CONCLUSION: 46% of the cohort of patients demonstrated CSWE. Among the patients with CSWE, there was increased prevalence of CSWE in the posterior circulation vasculature with particular predilection to the V4 vertebral artery segments (92%), although there was greater association of anterior circulation CSWE with risk factors for atherosclerosis. Patients with anterior circulation CSWE also demonstrated the most number of segments with CSWE. We therefore propose that CSWE, particularly in the anterior circulation, may portend early atherosclerosis.

Radiology Education in the Time of COVID-19: A Novel Distance Learning Workstation Experience for Residents.

RATIONALE AND OBJECTIVES: The coronavirus disease of 2019 (COVID-19) pandemic has challenged the educational missions of academic radiology departments nationwide. We describe a novel cloud-based HIPAA compliant and accessible education platform which simulates a live radiology workstation for continued education of first year radiology (R1) residents, with an emphasis on call preparation and peer to peer resident learning. MATERIALS AND METHODS: Three tools were used in our education model: Pacsbin (Orion Medical Technologies, Baltimore, MD, pacsbin.com), Zoom (Zoom Video Communications, San Jose, CA, zoom.us), and Google Classroom (Google, Mountain View, CA, classroom.google.com). A senior radiology resident (R2-R4) (n = 7) driven workflow was established to provide scrollable Digital Imaging and Communications in Medicine (DICOM) based case collections to the R1 residents (n = 9) via Pacsbin. A centralized classroom was created using Google Classroom for assignments, reports, and discussion where attending radiologists could review content for accuracy. Daily case collections over an 8-week period from March to May were reviewed via Zoom video conference readout in small groups consisting of a R2-R4 teacher and R1 residents. Surveys were administered to R1 residents, R2-4 residents, and attending radiologist participants. RESULTS: Hundred percent of R1 residents felt this model improved their confidence and knowledge to take independent call. Seventy-eight percent of the R1 residents (n = 7/9) demonstrated strong interest in continuing the project after pandemic related restrictions are lifted. Based on a Likert "helpfulness" scale of 1-5 with 5 being most helpful, the project earned an overall average rating of 4.9. Two R2-R4 teachers demonstrated increased interest in pursuing academic radiology. CONCLUSION: In response to unique pandemic circumstances, our institution implemented a novel cloud-based distance learning solution to simulate the radiology workstation. This platform helped continue the program's educational mission, offered first year residents increased call preparation, and promoted peer to peer learning. This approach to case-based learning could be used at other institutions to educate residents.

Bilateral Renal Infarction Secondary to Hypertrophic Cardiomyopathy.

Bilateral renal infarction is a rare phenomenon which can be difficult to diagnose because the symptoms may often mimic renal calculi, infection, muscle inflammation, genital diseases, myocardial infarction, or ischemia. We present the case of a 55-year-old male patient who presented with non-radiating, left-sided flank pain associated with nausea and vomiting. A computed tomography (CT) scan of the abdomen and pelvis with contrast demonstrated bilateral renal infarction. A thorough workup was initiated, and the thrombus formation due to left atrial enlargement from hypertrophic obstructive cardiomyopathy was considered as the cause of the bilateral renal infarction in this patient. The patient's renal function improved with treatment, and she was discharged on an anticoagulant, considering her left atrial enlargement and renal infarction.

XMRV: usage of receptors and potential co-receptors.

BACKGROUND: XMRV is a gammaretrovirus first identified in prostate tissues of Prostate Cancer (PC) patients and later in the blood cells of patients with Chronic Fatigue Syndrome (CFS). Although XMRV is thought to use XPR1 for cell entry, it infects A549 cells that do not express XPR1, suggesting usage of other receptors or co-receptors. METHODS: To study the usage of different receptors and co- receptors that could play a role in XMRV infection of lymphoid cells and GHOST (GFP- Human osteosarcoma) cells expressing CD4 along with different chemokine receptors including CCR1, CCR2, etc., were infected with XMRV. Culture supernatants and cells were tested for XMRV replication using real time quantitative PCR. RESULTS: Infection and replication of XMRV was seen in a variety of GHOST cells, LNCaP, DU145, A549 and Caski cell lines. The levels of XMRV replication varied in different cell lines showing differential replication in different cell lines. However, replication in A549 which lacks XPR1 expression was relatively higher than DU145 but lower than, LNCaP. XMRV replication varied in GHOST cell lines expressing CD4 and each of the co- receptors CCR1-CCR8 and bob. There was significant replication of XMRV in CCR3 and Bonzo although it is much lower when compared to DU145, A549 and LNCaP. CONCLUSION: XMRV replication was observed in GHOST cells that express CD4 and each of the chemokine receptors ranging from CCR1- CCR8 and BOB suggesting that infectivity in hematopoietic cells could be mediated by use of these receptors.