Background: The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide. Aims: We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy (MT), stroke, and intracranial hemorrhage (ICH) hospitalizations over a 3-month period at the height of the pandemic (March 1 to May 31, 2020) compared with two control 3-month periods (immediately preceding and one year prior). Methods: Retrospective, observational, international study, across 6 continents, 40 countries, and 187 comprehensive stroke centers. The diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases at participating centers. Results: The hospitalization volumes for any stroke, ICH, and MT were 26,699, 4,002, and 5,191 in the 3 months immediately before versus 21,576, 3,540, and 4,533 during the first 3 pandemic months, representing declines of 19.2% (95%CI,-19.7 to -18.7), 11.5% (95%CI,-12.6 to -10.6), and 12.7% (95%CI,-13.6 to -11.8), respectively. The decreases were noted across centers with high, mid, and low COVID-19 hospitalization burden, and also across high, mid, and low volume stroke/MT centers. High-volume COVID-19 centers (-20.5%) had greater declines in MT volumes than mid- (-10.1%) and low-volume (-8.7%) centers (p<0.0001). There was a 1.5% stroke rate across 54,366 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.9% (784/20,250) of all stroke admissions. Conclusion: The COVID-19 pandemic was associated with a global decline in the volume of overall stroke hospitalizations, MT procedures, and ICH admission volumes. Despite geographic variations, these volume reductions were observed regardless of COVID-19 hospitalization burden and pre-pandemic stroke/MT volumes.

MBIR performed better than ASIR 50% at providing diagnostically acceptable CT scans without compromising image quality and in the detection of colorectal liver metastases.

Initially Cone Beam CT was almost exclusively used to perform dental radiology. However, the first generation CBCT systems were later increasingly used to study sinuses, facial and nose fractures, temporomandibular joints etc. 3D-cephalometric head and neck studies became possible once CBCT systems were available that allowed scanning of the complete head. For this purpose a double rotation technique with stitching of the resulting two data sets was needed. CBCT systems on which the rotation could be stopped were needed to perform dynamic swallow or pharyngography studies. The advent of more powerful high-end CBCT systems led the way to temporal bone and skull base imaging. Finally, high-end "supine" CBCT systems using a "gantry" made small joint musculoskeletal imaging possible. These non-dental CBCT studies gradually replaced conventional X-rays and CT/MDCT studies because they allowed imaging with higher resolution, lower radiation dose and less metal artifacts. In this paper the most important non-dental CBCT indications will be discussed.

Dural carotid cavernous fistulas are usually treated via a transvenous approach through the inferior petrosal sinus. Surgical exposure and direct access to the superior ophthalmic vein have been previously described in situations in which conventional transvenous access, including the inferior petrosal sinus, is not possible. In this retrospective study of 20 patients, we report our results of imaging-guided percutaneous superior ophthalmic vein access in dural carotid cavernous fistula treatment. The superior ophthalmic vein was accessed after direct percutaneous puncture under sonographic guidance in 16 patients and biplane roadmap guidance in 4 patients. In all 20 patients, it was possible to access the superior ophthalmic vein and cure the dural carotid cavernous fistula. Two patients developed a retrobulbar hematoma after postseptal puncture, which required emergency lateral canthothomy. In our experience, direct imaging-guided percutaneous superior ophthalmic vein access is a safe alternative approach for treatment in situations in which conventional transvenous approaches are not possible. ABBREVIATIONS: dCCF ϭ dural carotid cavernous fistula; IPS ϭ inferior petrosal sinus; SOVϭ superior ophthalmic vein

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Purpose Multiphase computed tomography angiography (MP-CTA) is an innovative imaging tool that can give those managing acute ischemic stroke temporal information on degree and extent of pial collateral arterial filling in the affected brain. We sought to estimate the incidence of false-positive or -negative evaluation of the carotid bifurcation or intracranial thrombus on single-phase CTA (SP-CTA) compared with MP-CTA. Material and methods A single-center, retrospective consecutive review was conducted of imaging and clinical records of 150 patients in two months who presented with neurological symptoms with a National Institutes of Health Stroke Scale score ≥ 2 and who received an MP-CTA as part of their investigative work-up. The cohort consisted of 52.3% male and 47.7% female patients. Median individual age was 68 years (interquartile range 60–79). Extracranial and intracranial vessel images of the initial early arterial phase were evaluated and compared with late arterial and early venous phase images. Results In the cohort of 150 patients, in three patients (2%) SP-CTA would have led to an incorrect diagnosis and management without MP-CTA–acquired source imaging. The three scenarios represented differentiating a carotid string sign from internal carotid artery occlusion, determining the appearance and extent of thrombus in carotid T-occlusion, and differentiating slow flow and contrast mixing-related artifacts from intraluminal thrombus. Conclusions In addition to improving assessment of collateral circulation in acute stroke patients, MP-CTA is also useful in assessing specific flow-related scenarios for which SP-CTA may give spurious results.

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