diagnosis and imaging

Kara Jo Swafford, MD

Vagal A, Aviv R, Sucharew H, Reddy M, Hou Q, Michel P, et al. Collateral Clock Is More Important Than Time Clock for Tissue Fate: A Natural History Study of Acute Ischemic Strokes. Stroke. 2018

The ischemic penumbra represents hypo-perfused tissue at risk of infarction if cerebral blood flow is not restored and may persist for hours after onset of ischemia. Progression from penumbra to infarction may be delayed due to the presence of collateral circulation. The 2018 American Heart Association acute ischemic stroke guidelines, in part based on the results of the DAWN and DEFUSE 3 trials, support the use of perfusion imaging for identifying patients with potentially salvageable tissue to help in selecting appropriate candidates for mechanical thrombectomy. Limited data exists on penumbra characteristics in patients with untreated acute ischemic stroke compared to those receiving reperfusion therapy within a delayed time window (i.e., up to 24 hours after stroke onset). Vagal et al designed a multicenter retrospective cross-sectional study to investigate how time from stroke onset may affect penumbral salvage and infarct growth in untreated acute ischemic stroke patients within the first 24 hours, including the role of collaterals.

Shashank Shekhar, MD, MS
@Artofstroke

van Leijsen EMC, Kuiperij HB, Kersten I, Bergkamp MI, van Uden IWM, Vanderstichele H, et al. Plasma Aβ (Amyloid-β) Levels and Severity and Progression of Small Vessel Disease. Stroke. 2018

Leukoaraiosis, along with microbleeds and lacunes, are one of the most commonly encountered findings after a brain imaging in patients with multiple vascular risk factors. These changes are a result of small vessel disease (SVD). White matter disease is considered as a potential imaging marker for the development of dementia. Apart from traditional risk factors, e.g., hypertension, diabetes, etc., Aβ (amyloid β) has been proposed as an additional contributor to SVD. To investigate the association of plasma Aβ levels with severity and progression of SVD, the authors studied 487 participants in a prospective cohort RUN DMC study (Radboud University Nijmegen Diffusion Tensor and Magnetic Resonance Imaging Cohort).

Kaustubh Limaye, MD
@kaustubhslimaye

Gautheron V, Xie Y, Tisserand M, Raoult H, Soize S, Naggara O, et al. Outcome After Reperfusion Therapies in Patients With Large Baseline Diffusion-Weighted Imaging Stroke Lesions: A THRACE Trial (Mechanical Thrombectomy After Intravenous Alteplase Versus Alteplase Alone After Stroke) Subgroup Analysis. Stroke. 2018

The treatment landscape of acute ischemic stroke secondary to large vessel occlusion changed significantly in 2015 with the publication of 5 clinical trials that compared intravenous alteplase (IV t-pA) with IV t-pA and intra-arterial therapy (IAT). These clinical trials showed unequivocal benefit in reducing morbidity with the ESCAPE trial even showing mortality benefit. A similar trial conducted at 26 centers in France, THRACE (mechanical thrombectomy after intravenous alteplase versus alteplase alone after stroke) randomized 414 acute stroke patients with large vessel occlusion in either arm (IV t-PA vs IV tPA + IAT). 42 % of patients (IV tPA alone) vs. 53% (IV tPA +IAT) achieved functional independence [OR-1.55,95%CI 1.05-2.30; p-0.028], supporting data from the previous clinical trials. As this study was designed before the results of the IMS-III were published, it included patients treated within 4 hours of symptom onset. Other inclusion criteria were age 18-80 years, NIHSS 10-25, both anterior and posterior circulation and initiation of IAT within 5 hours.

Shashank Shekhar MD, MS
@Artofstroke

Ritzenthaler T, Cho T-H, Mechtouff L, Ong E, Turjman F, Robinson P, et al. Cerebral Near-Infrared Spectroscopy: A Potential Approach for Thrombectomy Monitoring. Stroke. 2017

The recently published article in Stroke highlights a rather novel and non-invasive way to monitor thrombectomy patients after large vessel occlusion. Monitoring recanalization and reperfusion during and after mechanical thrombectomy is a therapeutic and diagnostic challenge. In the past, the use of ultrasound and Electroencephalogram devices has been explored with some success. Using functional imaging like Near-infrared spectroscopy (NIRS) allows us to monitor the cerebral regional oxygen saturation continuously. This study is an attempt to answer the question if NIRS could be a better way to monitor mechanical thrombectomy patients.

This pilot study was performed in France using NIRS to find a correlation between regional brain oxygen saturation (rSO₂) and MRI perfusion based parameters, reperfusion and clinical outcome. A total of 17 patients were included in the study out of 749 consecutive ischemic admissions. The selection was based on occlusion in the anterior circulation on multimodal MRI with perfusion-weighted imaging. Patients were treated with standard thrombolysis and mechanical thrombectomy with successful recanalization defined as TICI score 2B and 3. NIRS optodes were placed on the bilateral forehead immediately after MRI and kept during mechanical thrombectomy and up to 24 hours. The NIRS device measures the interhemispheric differences (IHD) during this period.

Andrea Morotti, MD

Li Q, Liu Q-J, Yang W-S, Wang X-C, Zhao L-B, Xiong X, et al. Island Sign: An Imaging Predictor for Early Hematoma Expansion and Poor Outcome in Patients With Intracerebral Hemorrhage. Stroke. 2017

Intracerebral Hemorrhage (ICH) is a dynamic disease, with up to half of the patients experiencing active bleeding in the acute phase. Hematoma growth represents a potential therapeutic target to improve patients’ outcome. Rapid identification of subjects at high risk of hematoma growth is, therefore, crucial in clinical practice and in the setting of clinical trials testing anti-expansion treatments. The CT angiography (CTA) spot sign is a robust marker of ICH expansion. However, CTA is not available in many institutions, and a large proportion of ICH patients do not receive a CTA as part of their diagnostic workup ¹. This highlights the need for novel markers of hematoma growth that do not require a CTA.

Using a well-characterized cohort including 252 ICH patients, Qi Li and colleagues described the island sign, a novel marker of hematoma growth that can be evaluated on baseline non-contrast CT (NCCT). The island sign was defined as presence of at least 3 scattered small hematomas all separate from the main hemorrhage or at least 4 small hematomas, some or all of which may be connected with the main hemorrhage. An illustrative example of the island sign is provided in Figure 1. ICH expansion was defined as hematoma growth > 6mL or > 33% from baseline hematoma volume.

Figure 1. Illustration of island sign. Axial noncontrast computed tomography (CT) images of 4 patients with CT island sign.