Junghun Cho¹, John Lee², Hongyu An², Manu S Goyal², Yi Su³, and Yi Wang^1
1Weill Cornell Medicine, New York, NY, United States, ²Washington University School of Medicine, Saint Louis, MO, United States, ³Banner Alzheimers Institute, Phoenix, AZ, United States

Cerebral oxygen extraction fraction (OEF) maps are critical to investigate salvageable tissue in ischemic stroke. We compare OEF maps obtained using quantitative susceptibility mapping plus quantitative blood oxygen level-dependent modeling (QSM+qBOLD=QQ) with the reference standard OEF maps obtained using ¹⁵O PET in 10 healthy adults. The whole brain and regional average OEF values were found to be substantially equivalent between the two methods, e.g. 32.8 ± 6.7 % on PET and 34.2 ± 2.6 % on QQ (p=0.002, TOST) for whole brain average. QQ estimates OEF maps from a single routine MRI sequence without burdensome gas inhalation or respiratory-control procedures. 

Makoto Obara¹, Osamu Togao², Tatsuhiro Wada³, Chiaki Tokunaga³, Ryoji Mikayama³, Hiroshi Hamano¹, Kim van de Ven⁴, Masami Yoneyama¹, Tetsuo Ogino¹, Yuta Akamine¹, Yu Ueda¹, Jihun Kwon¹, and Marc Van Cauteren^5
1Philips Japan, Tokyo, Japan, ²Department of Molecular Imaging & Diagnosis, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, ³Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan, ⁴Philips Healthcare, Best, Netherlands, ⁵Philips Healthcare, Tokyo, Japan

The arterial transit time (ATT) calculated from multiple time points pseudo continuous arterial spin labeling (pCASL) has recently attracted attention. To calculate ATT accurately, while ensuring reliable SNR, we propose multiple repetition time (multi-TR) scheme, that is TR is varied according to the label duration (LD) and post label delay (PLD) with dynamically optimized BGS and 3D acquisition. The multi points data is efficiently acquired and scan time is less than 3 minutes for whole brain coverage. We conducted a feasibility test. Reliable background suppression effectiveness for all time points and a significant SNR gain were confirmed in healthy volunteers.

Stephan Kaczmarz¹, Miriam Reichert¹, Moritz Roman Hernandez Petzsche¹, Andreas Hock², Kilian Weiss³, Kim van de Ven⁴, Christine Preibisch¹, Jan Kirschke¹, Claus Zimmer¹, Makoto Obara⁵, Michael Helle⁶, Nico Sollmann^1,7, and Hans Liebl^1
1School of Medicine, Department of Neuroradiology, Technical University of Munich (TUM), Munich, Germany, ²Philips Healthcare, Horgen, Switzerland, ³Philips Healthcare, Hamburg, Germany, ⁴Philips Healthcare, Best, Netherlands, ⁵Philips Japan, Tokyo, Japan, ⁶University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany, ⁷Department of Radiology, University Ulm Medical Center, Ulm, Germany

Imaging of blood supply patterns is of high clinical interest to improve diagnostics in cerebrovascular diseases (CVD). However, the only clinically available imaging method is invasive digital subtraction angiography (DSA). We present data from 17 participants, including 7 CVD patients, with non-invasive MRI-based perfusion territory mapping by super-selective arterial spin labeling (ss-ASL) and time-resolved angiography by 4D-sPack with automated planning. Our results successfully confirmed automated planning even in CVD patients. Collateral pathways were non-invasively depicted by ss-ASL and 4D-sPack. Moreover, congruent results with DSA, contrast-enhanced MR-angiography and perfusion MRI demonstrated great potential for future routine application of ss-ASL and 4D-sPack.

Di Wu¹ and Shun Zhang^1
1Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China

This study aims to investigate spatiotemporal evolution of cerebral oxygen extraction fraction (OEF) in ischemic stroke with an MRI-based vascular-challenge-free method. The OEF of the infarcted area descends continuously from acute to chronic phase. Meanwhile, there exists tissue that is likely to be penumbra in the acute diffusion lesion, of which the OEF shows an increasing trend with time, suggesting timely reperfusion in this region. This MRI-based OEF mapping can precisely capture the heterogenous character of brain oxygen metabolism at different phases of ischemic stroke.

junxin wang¹, yanwei Miao¹, and Jiazheng Wang^2
1Department of Radiology, the First Affiliated Hospital of Dalian Medical University, Dalian, China, ²Phillips healthcare, dalian, China

This study aimed to exploit the early Wallerian degeneration (WD) along the corticospinal tract following cerebral ischemic stroke using amide proton transfer weighted (APTw) and diffusion weighted imaging (DWI). This study included 34 patients with acute cerebral infarction and 21 healthy adult controls. Our data suggested that APTw and apparent diffusion coefficient (ADC) values 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 and ADC in early detection of WD following cerebral ischemic stroke.

Zengping Lin¹, Tianyao Wang², Rong Guo^3,4, Yudu Li^3,4, Yibo Zhao^3,4, Tianxiao Zhang¹, Jun Liu², Xin Yu⁵, Zhi-Pei Liang^3,4, and Yao Li^1
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China, ²Radiology Department, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China, ³Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁴Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁵Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States

Determination of ischemic stroke onset time is critical in ischemic stroke treatment. ¹H-MRSI has been recognized as a potentially powerful tool for noninvasive metabolic imaging, which showed great promise for the assessment of stroke onset time. This study investigated changes of neurometabolite concentrations in lesion after different symptom onset time in ischemic stroke patients using a fast high-resolution 3D MRSI technique. Our results showed that NAA concentration within the ischemic lesion decreased in a time-dependent manner after stroke onset, which might provide a useful metabolic biomarker for assessment of symptom onset time.

Yuhan Jiang¹, Peipei Chang¹, Yingqiu Liuyang¹, Bingbing Gao¹, Yiwei Che¹, Renwang Pu¹, Qingwei Song¹, Ailian Liu¹, Zhiwei Shen², Jiazheng Wang², and Yanwei Miao^1
1the First Affiliated Hospital of Dalian Medical University, Dalian, China, ²Philips Healthcare, Beijing, China

Amide proton transfer weighted (APTw) MRI has been increasingly applied in the study of stroke based on its ability to detect pH and intracellular proteins content. In subacute infarction, the heterogeneity of APTw signal may reflect the clinical treatment efficacy of patients. In this study, we found that there is negative correlation between the heterogeneity signals (APTw_max-min) in the ischemic regions and the difference of NIHSS scores on the day of hospital admission and leaving (∆NIHSS). Therefore, the heterogeneity of APTw signal is potentially an effective imaging biomarker to predict the efficacy of patients with subacute cerebral infarction.

Bing-Fong Lin¹, Po-Yi Tsai², and Chia-Feng Lu^1
1Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan, ²Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei, Taiwan

Low-frequency repetitive transcranial magnetic stimulation (rTMS) provided promising results to facilitate the language recovery in stroke patients with non-fluent aphasia. This study demonstrated that the contralesional inhibitory rTMS treatment can induce the functional reorganization within language networks and recovery of language function in chronic aphasic stroke. The correlation analysis further revealed the association between altered functional connectivity and improved language ability after rTMS treatment. Finally, we reported that the involved functional circuits for the language recovery may depend on lesion location and size of stroke.

Bin Bo¹, Tianyao Wang², Rong Guo^3,4, Yudu Li^3,4, Yibo Zhao^3,4, Tianxiao Zhang¹, Zengping Lin¹, Ziyu Meng¹, Jun Liu², Xin Yu⁵, Zhi-Pei Liang^3,4, and Yao Li^1
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China, ²Radiology Department, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China, ³Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁴Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁵Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States

Detection of neurometabolic alterations in stroke patients from acute to subacute stages could provide useful information for brain tissue salvage therapy. Fast high-resolution 3D ¹H-MRSI by SPICE has previously provided nearly whole-brain neurometabolic mapping in acute stroke patients. In this pilot study, we investigated the alterations of neurometabolites in a longitudinal cohort of ischemic stroke patients. Our preliminary results showed observable changes of different neurometabolites in different regions within the hypoperfused tissue of stroke patients from acute to subacute stages. Our study may lay a foundation for further investigation of temporal changes of neurometabolic biomarkers during stroke progression.

Di Wu¹, Shun Zhang¹, and Weiyin Vivian Liu^2
1Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China, ²MR Research, GE Healthcare, Beijing, China, Beijing, China

This study aims to investigate oxygen metabolic, neuroinflammatory and hemodynamic parameters in different parts of the ischemic stroke lesions using multi-modal MRI. Significant difference of cerebral blood flow (CBF) was found between patients with and without penumbra. The oxygen extraction fraction (OEF) and nonblood susceptibility of tissue in the penumbra were significantly different from ischemic core, revealing benign oxygen metabolic compensation and less neuroinflammation in the penumbra. OEF in the diffusion lesion was positively correlated with clinical severity and continuously decreased with time. Multi-modal MRI-based markers can accurately reflect the pathophysiologic discrepancy in different regions of the ischemic stroke lesions.