Delayed Contrast-Enhanced MR Angiography for the Assessment of Internal Carotid Bulb Patency in the Context of Acute Ischemic Stroke: An Accuracy, Interrater, and Intrarater Agreement Study.

BACKGROUND AND PURPOSE: CTA has shown limited accuracy and reliability in distinguishing tandem occlusions and pseudo-occlusions on initial acute stroke imaging. The utility of early and delayed contrast-enhanced MRA in this setting is unknown. We aimed to assess the accuracy and reliability of early and delayed contrast-enhanced MRA for carotid bulb patency in patients with acute ischemic stroke. MATERIALS AND METHODS: We retrospectively reviewed patients who had ICA occlusion and underwent thrombectomy with preprocedural early and delayed contrast-enhanced MRA in a single comprehensive stroke center. During 2 sessions, 10 raters independently assessed 32 cases with early contrast-enhanced MRA (with an additional delayed contrast-enhanced MRA sequence during the second reading session). Their judgments were compared with DSA as a reference standard. Accuracy and interrater agreement were measured. Five raters undertook a third reading session to assess intrarater agreement. RESULTS: Accuracy for the assessment of carotid bulb patency with early contrast-enhanced MRA was limited (69%; 95% CI, 59%-79%), with moderate interrater agreement (κ = 0.42; 95% CI, 0.27-0.55). The second reading with an additional delayed contrast-enhanced MRA sequence improved both accuracy (82%; 95% CI, 73%-91%; P < .001) (raters corrected 43%-77% of incorrect diagnoses with early contrast-enhanced MRA alone; mean = 59%) and interrater agreement (κ = 0.56; 95% CI, 0.41-0.73; P = .07). Intrarater agreement was almost perfect, substantial, and moderate for 3, 1, and 1 raters. CONCLUSIONS: Early contrast-enhanced MRA has limited accuracy and repeatability for the evaluation of carotid bulb patency in acute ischemic stroke. The additional delayed contrast-enhanced MRA sequence may improve accuracy and reliability.

Clinical description of the broad range of neurological presentations of COVID-19: A retrospective case series.

BACKGROUND: Neurological disorders associated with SARS-CoV-2 infection represent a clinical challenge because they encompass a broad neurological spectrum and may occur before the diagnosis of COVID-19. METHODS: In this monocentric retrospective case series, medical records from patients with acute neurological disorders associated with SARS-CoV-2 infection from medicine departments of an academic center in Paris area were collected between March 15th and May 15th 2020. Diagnosis of SARS-CoV-2 was ascertained through specific RT-PCR in nasopharyngeal swabs or based on circulating serum IgG antibodies. RESULTS: Twenty-six patients diagnosed with SARS-CoV-2 infection presented with neurological disorders: encephalitis (N=8), encephalopathy (N=6), cerebrovascular events (ischemic strokes N=4 and vein thromboses N=2), other central nervous system (CNS) disorders (N=4), and Guillain-Barré syndrome (N=2). The diagnosis of SARS-CoV-2 was delayed on average 1.6 days after the onset of neurological disorder, especially in case of encephalitis 3.9 days, encephalopathy 1.0 day, and cerebrovascular event 2.7 days. CONCLUSIONS: Our study confirms that COVID-19 can yield a broad spectrum of neurological disorders. Because neurological presentations of COVID-19 often occur a few days before the diagnosis of SARS-COV-2 infection, clinicians should take preventive measures such as patient isolation and masks for any new admission to avoid nosocomial infections. Anti-SARS-CoV2 antibody detection in RT-PCR SARS CoV-2 negative suspected cases is useful to confirm a posteriori the diagnosis of atypical COVID-19 presentations.

Intravenous thrombolysis and thrombectomy decisions in acute ischemic stroke: An interrater and intrarater agreement study.

PURPOSE: We aimed to assess agreement on intravenous tissue-plasminogen activator (IV tPA) and mechanical thrombectomy (MT) management decisions in acute ischemic stroke (AIS) patients. Secondary objectives were to assess agreement on Diffusion-Weighted-Imaging-Alberta-Stroke-Program-EArly-CT-Score (DWI-ASPECTS), and clinicians' willingness to recruit patients in a randomized controlled trial (RCT) comparing medical management with or without MT. MATERIALS AND METHODS: Studies assessing agreement of IV tPA and MT were systematically reviewed. An electronic portfolio of 41 AIS patients was sent to randomly selected providers at French stroke centers. Raters were asked 4 questions for each case: (1) What is the DWI-ASPECTS? (2) Would you perform IV tPA? (3) Would you perform MT? (4) Would you include the patient in a RCT comparing standard medical therapy with or without MT? Twenty responders were randomly selected to study intrarater agreement. Agreement was assessed using Fleiss' Kappa statistics. RESULTS: The review yielded two single center studies involving 2-5 raters, with various results. The electronic survey was answered by 86 physicians (60 vascular neurologists and 26 interventional neuroradiologists). The interrater agreement was moderate for IV tPA treatment decisions (κ=0.565 [0.420-0.680]), but only fair for MT (κ=0.383 [0.289-0.491]) and for combined treatment decisions (κ=0.399 [0.320-0.486]). The intrarater agreement was at least substantial for the majority of raters. The interrater agreement for DWI-ASPECTS was fair (κ=0.325 [0.276-0.387]). Physicians were willing to include a mean of 14±9 patients (33.1%±21.7%) in a RCT. CONCLUSION: Disagreements regarding the use of IVtPA or MT in the management of AIS patients remain frequent. Further trials are needed to resolve the numerous areas of uncertainty.

Blood Flow Mimicking Aneurysmal Wall Enhancement: A Diagnostic Pitfall of Vessel Wall MRI Using the Postcontrast 3D Turbo Spin-Echo MR Imaging Sequence.

Our aim was to compare the detectability of aneurysmal wall enhancement in unruptured intracranial aneurysms between conventional and motion-sensitized driven equilibrium-prepared postcontrast 3D T1-weighted TSE sequences (sampling perfection with applicationoptimized contrasts by using different flip angle evolution, SPACE). Twenty-two patients with 30 unruptured intracranial aneurysms were scanned at 3T. Aneurysmal wall enhancement was more significantly detected using conventional compared with motion-sensitized driven equilibrium-prepared SPACE sequences (10/30 versus 2/30, P < .0001). Contrast-to-noise ratio measurements did not differ between conventional and motion-sensitized driven equilibrium-prepared sequences (P = .51). Flowing blood can mimic aneurysmal wall enhancement using conventional SPACE sequences with potential implications for patient care.

Intracranial Arteriovenous Shunting: Detection with Arterial Spin-Labeling and Susceptibility-Weighted Imaging Combined.

BACKGROUND AND PURPOSE: Arterial spin-labeling and susceptibility-weighted imaging are 2 MR imaging techniques that do not require gadolinium. The study aimed to assess the accuracy of arterial spin-labeling and SWI combined for detecting intracranial arteriovenous shunting in comparison with conventional MR imaging. MATERIALS AND METHODS: Ninety-two consecutive patients with a known (n = 24) or suspected arteriovenous shunting (n = 68) underwent digital subtraction angiography and brain MR imaging, including arterial spin-labeling/SWI and conventional angiographic MR imaging (3D TOF, 4D time-resolved, and 3D contrast-enhanced MRA). Arterial spin-labeling/SWI and conventional MR imaging were reviewed separately in a randomized order by 2 blinded radiologists who judged the presence or absence of arteriovenous shunting. The accuracy of arterial spin-labeling/SWI for the detection of arteriovenous shunting was calculated by using the area under receiver operating curve with DSA as reference standard. κ coefficients were computed to determine interobserver and intermodality agreement. RESULTS: Of the 92 patients, DSA showed arteriovenous shunting in 63 (arteriovenous malformation in 53 and dural arteriovenous fistula in 10). Interobserver agreement was excellent (κ =0.83-0.95). In 5 patients, arterial spin-labeling/SWI correctly detected arteriovenous shunting, while the conventional angiographic MR imaging did not. Compared with conventional MR imaging, arterial spin-labeling/SWI was significantly more sensitive (0.98 versus 0.90, P = .04) and equally specific (0.97) and showed significantly higher agreement with DSA (κ = 0.95 versus 0.84, P = .01) and higher area under the receiver operating curve (0.97 versus 0.93, P = .02). CONCLUSIONS: Our study showed that the combined use of arterial spin-labeling and SWI may be an alternative to contrast-enhanced MRA for the detection of intracranial arteriovenous shunting.

Reduced-dose CT protocol for the assessment of cerebral vasospasm.

INTRODUCTION: Despite the increased radiation dose, multimodal CT including noncontrast CT (NCT), CT angiography (CTA), and perfusion CT (PCT) remains a useful tool for the diagnosis of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to assess the radiation dose and the image quality between a standard-dose and a reduced-dose multimodal CT protocol. METHODS: The study group consisted of 26 aSAH patients with a suspicion of DCI on clinical examination and transcranial doppler. Two different CT protocols were used: a standard-dose protocol (NCT 120 kV, 350 mAs; CTA 100 kV, 250 mAs; PCT 80 kV, 200 mAs) from August 2011 to October 2013 (n = 13) and a reduced-dose protocol (NCT 100 kV, 400 mAs; CTA 100 kV, 220 mAs; PCT 80 kV, 180 mAs) from November 2013 to May 2014 (n = 13). Dose-length product (DLP), effective dose, volume CT dose index (CTDI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and overall image quality were determined for each examination. RESULTS: The overall image quality was judged as good or excellent in all cases. The reduced-dose protocol allowed a 15 % decrease in both the median total DLP (2438 vs 2898 mGy cm, p < 0.0001) and the effective dose as well as a significant decrease in median CTDI of 23, 31, and 10 % for NCT, CTA, and CTP, respectively. This dose reduction did not result in significant alteration of SNR (except for NCT) or CNR between groups. CONCLUSION: The present study showed that the reduced-dose multimodal CT protocol enabled a significant reduction of radiation dose without image quality impairment.

Double inversion recovery MR sequence for the detection of subacute subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The diagnosis of subacute subarachnoid hemorrhage is important because rebleeding may occur with subsequent life-threatening hemorrhage. Our aim was to determine the sensitivity of the 3D double inversion recovery sequence compared with CT, 2D and 3D FLAIR, 2D T2*, and 3D SWI sequences for the detection of subacute SAH. MATERIALS AND METHODS: This prospective study included 25 patients with a CT-proved acute SAH. Brain imaging was repeated between days 14 and 16 (mean, 14.75 days) after clinical onset and included MR imaging (2D and 3D FLAIR, 2D T2*, SWI, and 3D double inversion recovery) after CT (median delay, 3 hours; range, 2-5 hours). A control group of 20 healthy volunteers was used for comparison. MR images and CT scans were analyzed independently in a randomized order by 3 blinded readers. For each subject, the presence or absence of hemorrhage was assessed in 4 subarachnoid areas (basal cisterns, Sylvian fissures, interhemispheric fissure, and convexity) and in brain ventricles. The diagnosis of subacute SAH was defined by the presence of at least 1 subarachnoid area with hemorrhage. RESULTS: For the diagnosis of subacute SAH, the double inversion recovery sequence had a higher sensitivity compared with CT (P < .001), 2D FLAIR (P = .005), T2* (P = .02), SWI, and 3D FLAIR (P = .03) sequences. Hemorrhage was present for all patients in the interhemispheric fissure on double inversion recovery images, while no signal abnormality was noted in healthy volunteers. Interobserver agreement was excellent with double inversion recovery. CONCLUSIONS: Our study showed that the double inversion recovery sequence has a higher sensitivity for the detection of subacute SAH than CT, 2D or 3D FLAIR, 2D T2*, and SWI.