Ryan A. Rava^1,2, Muhammad Waqas^2,3, Kenneth V. Snyder^2,3, Elad I. Levy^2,3, Adnan H. Siddiqui^2,3, Jason M. Davies^2,3, Xiaoliang Zhang¹, and Ciprian N. Ionita^1,2,3
1Biomedical Engineering, University at Buffalo, Buffalo, NY, United States, ²Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, United States, ³Neurosurgery, University at Buffalo, Buffalo, NY, United States

FLAIR MRI has the potential to provide more accurate ground truth infarct labels compared with DWI for the purpose of software validation and determination of ischemic stroke patient eligibility for thrombectomy. Currently, accurate segmentation of infarct has hindered the use of FLAIR infarct labels due to skull and erroneous image intensity values being similar to those of infarct lesions. In this study, an automated segmentation technique was developed for segmentation of infarct tissue from FLAIR MRI and performance metrics comparing this method to manually segmented infarct (FLAIR Sorenson-Dice=0.8168, DWI Sorenson-Dice=0.7922) indicate this technique is non-inferior to the current standard (DWI).

Tao Jin^1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States

Stroke onset time is a prerequisite for thrombolytic treatment but is unknown in ~25% of acute ischemic stroke patients. A fluid-attenuated inversion recovery (FLAIR)-based MRI index (e.g., DWI-FLAIR mismatch) has been suggested as a surrogate to determine whether the stroke duration is within the treatment window. In this work, we showed that the time when a positive FLAIR contrast appears between ischemic and normal tissue increases with B₀, and is dependent on the imaging parameters. Therefore, FLAIR-based studies of stroke onset should be designed or interpreted with care.

Lena Schmitzer¹, Stephan Kaczmarz^1,2, Nico Sollmann¹, Claus Zimmer¹, Christine Preibisch^1,3, and Jens Göttler^1,2,4
1School of Medicine, Department of Neuroradiology, Technical University of Munich, Munich, Germany, ²MRRC, Yale University, New Haven, CT, United States, ³School of Medicine, Clinic of Neurology, Technical University of Munich, Munich, Germany, ⁴School of Medicine, Department of Radiology, Technical University of Munich, Munich, Germany

Internal carotid artery stenosis (ICAS) is a well-known risk factor for stroke. However, treatment efficacy evaluations are currently limited by widely unknown ICAS-effects on brain microstructure. Two promising parameters to study pathophysiological changes in white matter (WM) are fractional anisotropy (FA) and mean diffusivity (MD), derived from established diffusion-tensor imaging. We evaluated FA- and MD-maps in 15 ICAS-patients before and after revascularization. Our results demonstrated globally unimpaired FA and MD before treatment, even in watershed areas, which are especially vulnerable to hemodynamic impairments. Postinterventional structural results were stable. Thus, absence of ischemic events and successful treatment are indicated.

Bryony L. McGarry¹, Robin A. Damion¹, Terence J. Norton¹, Michael J. Knight¹, Philip L. Clatworthy², George W.J. Harston³, Keith W. Muir⁴, and Risto A. Kauppinen^5
1School of Psychological Science, University of Bristol, Bristol, United Kingdom, ²Stroke Neurology, North Bristol NHS Trust, Bristol, United Kingdom, ³Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom, ⁴Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom, ⁵Faculty of Engineering, University of Bristol, Bristol, United Kingdom

Unknown onset time is a common contradiction for anti-thrombolytic treatment of ischemic stroke. T₂ relaxation times within the lesion estimate onset time, but accuracy may be affected by dependence on the non-ischemic hemisphere as reference for pre-ischemic values. In hyperacute ischemic stroke patients, we tested a reference-independent approach shown to be an accurate timer in a preclinical stroke model. This involved modelling the T₂ distribution within ADC defined lesions to design linear regression models for onset time estimation. The reference-independent approach was accurate in grey matter and for lesions containing grey and white matter, the reference-dependent approach was more accurate. 

Guomin Li¹, Hui Liu², Qi Liu², Yongquan Ye², Yichen Hu², Haodong Qin³, Jun Xie³, Jianhao Yan⁴, Yang Xin³, and Guihua Jiang^4
1Medical Imaging, Guangdong Second Provincial General Hospital, Guangzhou, China, ²UIH America, Inc., Houston, TX, United States, ³United Imaging Healthcare, Shanghai, China, ⁴Guangdong Second Provincial General Hospital, Guangzhou, China

In this study, APT, SWI-QSM,  ASL-CBF, and DWI imaging are compared and evaluated in stroke patients, with a focus on different values in identifying diseased area and helping to provide better prognosis.

Junxin Wang¹, Yanwei Miao¹, Jiazheng Wang², Zhiwei Shen², Bingbing Gao¹, Yu Bing¹, Yunan Cui¹, Ailian Liu¹, and Qingwei Song^1
1Department of Radiology, the First Affiliated Hospital of Dalian Medical University, Dalian, China, ²Phillips healthcare, China, China

The study aimed to evaluate the significance of amide proton transfer weighted (APTw) imaging in the early diagnosis of pyramidal tract Wallerian degeneration (WD) following cerebral infarction. This study included 25 patients with acute cerebral infarction and 12 healthy adult controls. Our data suggested that the value of APTw was significantly increased on ipsilateral compared to contralateral and the control group in the posterior limb of internal capsule. It proves the feasibility of APTw in early detection of WD.

Yuhan Jiang¹, Yanwei Miao¹, Peipei Chang¹, Zhongping Zhang², Yiwei Che¹, Ailian Liu¹, Qingwei Song¹, and Jiazheng Wang^2
1the First Affiliated Hospital of Dalian Medical University, Dalian, China, Dalian, China, ²Philips Healthcare, Beijing, China, Beijing, China

The relationship between APTw and regional cerebral oxygen metabolism levels in the ischemic area is unclear. This study attempts to investigate the mechanism of ischemic tissue pH changes and its influencing factors by measuring the APTw value of ischemic tissue, combined with ASL and SWI. We found that the phase differences of the veins in the infarct (Δφlesion) is positively correlated with APTWmax and APTWmax-min in the ischemic penumbra at PLD1.5.

Stephan Kaczmarz^1,2, Jens Göttler^1,2,3, Jan Petr⁴, Nico Sollmann¹, Lena Schmitzer¹, Andreas Hock⁵, Mikkel Bo Hansen⁶, Kim Mouridsen⁶, Claus Zimmer¹, Fahmeed Hyder², and Christine Preibisch^1,7
1School of Medicine, Department of Neuroradiology, Technical University of Munich, Munich, Germany, ²MRRC, Yale University, New Haven, CT, United States, ³School of Medicine, Department of Radiology, Technical University of Munich, Munich, Germany, ⁴Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany, ⁵Philips Healthcare, Hamburg, Germany, ⁶Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark, ⁷School of Medicine, Clinic of Neurology, Technical University of Munich, Munich, Germany

Hemodynamic MRI is highly promising to improve treatment decisions in asymptomatic internal carotid artery stenosis (ICAS). However, treatment efficacy evaluations require clinically applicable techniques, such as dynamic susceptibility contrast (DSC) and resting-state BOLD-based evaluations of amplitude of low-frequency fluctuations (ALFF). We present data from 16 asymptomatic ICAS patients before and after treatment and 17 age-matched healthy controls measuring cerebral blood volume (CBV) and capillary transit-time heterogeneity (CTH) by DSC and ALFF with additional cognitive testing. We hypothesized recovery of hemodynamic impairments after revascularization. Our results confirmed this hypothesis for all parameters. Interestingly, at the same time cognitive function remained impaired.

Gavin J B Elias¹, Philippe De Vloo², Jürgen Germann¹, Alexandre Boutet¹, Robert M Gramer¹, Suresh E Joel³, Bart Morlion², Bart Nuttin², and Andres M Lozano^1
1University Health Network, Toronto, ON, Canada, ²University Hospitals Leuven, Leuven, Belgium, ³GE Global Research, Bangalore, India

Despite the prevalence of central post-stroke pain (CPSP), pain-causing brain lesions remain incompletely understood. In 17 CPSP patients receiving invasive neuromodulation, we utilized voxelwise odds-ratio mapping and normative resting state fMRI to identify high-risk pain hotspots and describe functional networks associated with CPSP lesions and analgesic stimulation. Highest-risk CPSP hotspots were located in somatosensory thalamus/white matter and connected to a network comprising anterior cingulate cortex, insula, thalamus, and inferior parietal lobule. Posterior insula and thalamus were also coupled to therapeutic deep brain stimulation volumes. These findings elucidate CPSP’s topography and connectivity while informing the network-level mechanism of analgesic neuromodulation.