Comparing the benefit of ASPECTS on maximum intensity projection images of computed tomography angiography to source images and noncontract computed tomography in predicting infarct volume and collaterals extent.

INTRODUCTION: In acute ischemic strokes (AIS), the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and CT perfusion (CTP) are commonly used to determine mechanical thrombectomy eligibility. Prior work suggests that CTA source image (CTA-SI) ASPECTS (CTAasp) and a newly described CTA maximum intensity projection (CTA-MIP) ASPECTS (MIPasp) better predict the final infarct core. Our goal was to compare MIPasp to CTAasp and non-contrast CT ASPECTS (NCCTasp) for predicting ischemic core and collaterals established by CTP. METHODS AND MATERIALS: A single institution, retrospective database for AIS due to internal carotid artery (ICA) or proximal middle cerebral artery (MCA) occlusions between January 2016 and February 2021 was reviewed. We rated ASPECTS on NCCT, CTA-SI, and CTA-MIP at baseline, then used the automated RAPID software to measure CTP ischemic core volume. The accuracy of each ASPECTS in predicting ischemic core volume (ICV) >70 cc and Hypoperfusion intensity ratio (HIR) >0.4 was compared using the receiver operating characteristic (ROC) curve. RESULTS: 122/319 patients fulfilled the inclusion criteria. Area under the curve (AUC) for MIPasp was significantly higher than NCCTasp and CTAasp for predicting ICV >70 cc (0.95 vs. 0.89 and 0.95 vs. 0.92, P =0.03 and P = 0.04). For predicting HIR >0.4, AUC for MIPasp was significantly higher than NCCTasp and CTAasp (0.85 vs. 0.72 and 0.85 vs. 0.81, P < 0.001 and P < 0.01). CONCLUSION: The predictive accuracy of detecting ischemic stroke with ICV >70cc and HIR >0.4 can be significantly improved using the MIPasp instead of CTAasp or NCCTasp.

Major radiological outcomes of CTA head and neck performed for dizziness in a major academic Emergency Department.

Purpose: Routine head and neck CTAs (CTAhead+neck) performed for dizziness in the Emergency Department (ED) has steadily increased, but its clinical utility is still poorly elucidated. Our purpose was to assess the radiologic outcomes of CTAhead+neck in ED dizziness patients.Methods: ED dizziness patients with CTAhead+neck from January 2010 through November 2019 were retrospectively identified and further stratified into central vertigo (CV), peripheral vertigo (PV), and non-specific dizziness (NSD) groups by final clinical diagnoses. Findings on CTAhead+neck (vessel stenosis >50%, occlusion, dissection, and infarct), and infarct on subsequent MRI if performed, were assessed. Differences in imaging findings were analyzed using chi-square or Fisher's exact tests.Results: Of 867 dizziness patients, 88 were diagnosed with CV, 383 with PV, and 396 with NSD. On CTAhead+neck, 11.4% of all patients had posterior CTA findings, including posterior occlusions (4.2%), dissections (1.2%), and infarcts (2.3%). CV patients had more posterior circulation findings (31.8%) versus PV (9.9%) and NSD (8.3%) patients (both p < 0.01). 21.6% of CV patients had acute infarcts on CT versus none for PV and 0.03% for NSD patients (both p < 0.01). On MRI, 46.6% of CV patients had acute posterior circulation infarcts versus none for PV and 0.3% for NSD patients (p < 0.01).Conclusion: Diagnostic yield for CTAhead+neck for dizziness patients is low except in central vertigo patients which constitute only 1/10th of CTAs performed. Our single institution results support that CTAhead+neck is likely low-yield in patients with high clinical suspicion for PV or NSD and further studies are needed to test this hypothesis.

MRI findings differentiating tonsillar herniation caused by idiopathic intracranial hypertension from Chiari I malformation.

PURPOSE: Some patients with idiopathic intracranial hypertension (IIH) have cerebellar tonsillar herniation ≥ 5 mm mimicking Chiari malformation I (CMI), which can result in misdiagnosis and unjustified treatment. Our purpose was to identify IIH patients with tonsillar herniation ≥ 5 mm (IIHTH) and compare with CMI patients to assess imaging findings that could distinguish the two conditions. METHODS: Ninety-eight patients with IIH, 81 patients with CMI, and 99 controls were retrospectively assessed. Two neuroradiologists blindly reviewed MR images. IIHTH patients were compared with CMI patients and controls regarding the extent of tonsillar herniation (ETH), bilateral transverse sinus stenosis (BTSS), hypophysis-sella ratio (HSR), and bilateral tortuosity of optic nerve (BTON). RESULTS: 13/98 (13.2%) IIH patients had tonsillar herniation ≥ 5 mm (IIHTH) and were significantly younger and had higher BMI compared with CMI patients and controls. ETH was significantly less in the IIHTH than CMI (6.5 ± 2.4 mm vs. 10.9 ± 4.4 mm; p < 0.001). BTSS and HSR < 0.5 were more common in IIHTH than CMI (p < 0.001 and p = 0.003, respectively). No differences were seen between CMI and controls. BTON was significantly more common in IIHTH compared to control (p = 0.01) but not to the CMI (p = 0.36). Sensitivity and specificity to differentiate IIHTH from CMI were 69.2% and 96.1% for BTSS and 69.2% and 75.3% for HSR < 0.5. CONCLUSION: The presence of BTSS and/or HSR < 0.5 in patients with ETH ≥ 5 mm should suggest further evaluation to exclude IIH before considering CMI surgery.

Rapid Endovascular Treatment of Acute Ischemic Stroke: What a General Radiologist Should Know.

Stroke is the second leading cause of mortality and the third leading cause of disability-adjusted life-years worldwide. For each minute of an ischemic stroke, an estimated 1.9 million brain cells die. The year 2015 saw the unprecedented publication of 5 multicentre, randomized, controlled trials. These studies showed that patients with acute ischemic stroke caused by large-vessel thrombus occlusion of the proximal anterior circulation had significantly reduced disability at 90 days when treated with endovascular thrombectomy and usual stroke care compared to usual stroke care alone. As a result, endovascular thrombectomy is now the new North American and European standard of care for suitable patients with acute ischemic stroke caused by large-vessel proximal anterior circulation occlusion. We review key take-home messages in this paradigm shift for radiologists, including the importance of time and workflow efficiency, what currently constitutes appropriate preimaging patient selection and imaging criteria, the use of newer generation thrombectomy devices, safety outcomes, as well as further areas still in need of elucidation.

LVIS Jr 'shelf' technique: an alternative to Y stent-assisted aneurysm coiling.

Wide-necked bifurcation intracranial aneurysms have traditionally not been amenable to coil embolization with the use of a single stent due to the high risk of coil prolapse. Y-configuration double stent-assisted coil embolization ('Y-stenting') of this aneurysm type has been shown to have generally good clinical outcomes, although the technique is complex with various challenges described in the literature. The compliant and flexible closed-cell design of braided stents such as the LVIS Jr allows for the creation of a 'shelf' across the aneurysm neck sufficient to prevent coil prolapse. We describe this novel 'shelf' technique and present a small case series of LVIS Jr stent-assisted wide-necked bifurcation intracranial aneurysm coiling in eight patients. Our small, albeit important, case series demonstrates that the 'shelf' technique is feasible and safe with very good short-term clinical and angiographic outcomes, and may obviate the need for Y-stenting.

Impact of simulator training on resident cataract surgery.

BACKGROUND: Virtual reality surgery simulation training improves resident performance as measured by the simulator itself and wet-lab performance. This study aims to determine whether virtual surgery simulator training improves actual resident cataract surgery performance. METHODS: The first 50 phacoemulsification cases of 20 residents, at a single residency program (Henry Ford Hospital), were retrospectively compared as two groups: before (2007-8) and after (2009-10) introduction of the Eyesi virtual surgery simulator to the surgical training program. Primary outcomes were the incidence of posterior capsule tears and operation duration. All residents received traditional didactic and wet-lab training. Instructor surgeons were surveyed for their impression of the simulator's contribution to resident surgical training. RESULTS: The nonsimulator and simulator groups each comprised 500 cases with 40 and 35 posterior capsule tears respectively. Capsular tear rates for the nonsimulator and simulator groups were 8.8 % and 10 % respectively for the first 25 cases, and 7.2 % and 3.6 % (P = 0.11) respectively for cases 26 through 50 . The percentage of long cases (defined as >40 min) for cases 10 through 50 was 42.3 % and 32.4 % (P = 0.005) for the nonsimulator and simulator groups respectively. CONCLUSIONS: Virtual reality surgical simulator training mildly shortens the learning curve for the first 50 phacoemulsification cases. The less adept residents appear to benefit most.