MRI in Stroke: Oxygen, Metabolism & Tissue Function
Neuro Thursday, 20 May 2021

Oral Session - MRI in Stroke: Oxygen, Metabolism & Tissue Function
Neuro
Thursday, 20 May 2021 18:00 - 20:00
  • Cerebral oxygen extraction fraction (OEF): comparison of challenge-free gradient echo QSM+qBOLD (QQ) with 15O PET in healthy adults
    Junghun Cho1, John Lee2, Hongyu An2, Manu S Goyal2, Yi Su3, and Yi Wang1
    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
    Gradient echo MRI-based QSM+qBOLD (QQ)-OEF mapping is validated against the reference standard 15O PET-OEF mapping in healthy adults, with providing substantially equivalent OEF values both globally and regionally.
    Figure 1. OEF maps from PET and QQ in axial, sagittal, and coronal views in a subject. Both PET and QQ show uniform OEF maps and good agreement between scans and methods.
    Figure 3. OEF comparison in cortical gray matters (A-E), white matter (F), and deep gray matters (G-J) among PET and QQ average. No significant difference was found between PET and QQ (all p-values <0.01, TOST). The unit in y-axis is %. Red line, blue box, black whisker, and red cross, black circle indicates median value, interquartile range, the range extending to 1.5 of the interquartile range, outlier beyond the whisker range, and individual subject value.
  • Pseudo-Continuous Arterial Spin Labeling using Multiple Label- and Post-Label Duration with Dynamically Optimized Background Suppression
    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 Cauteren5
    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 feasibility of multiple repetition time scheme with dynamically optimized background suppression (BGS) in pseudo continuous arterial spin labeling was suggested. Reliable background suppression effectiveness and a significant SNR gain were confirmed in healthy volunteers.
    Figure 1: multi-TR scheme: a) Schematic drawings of the multi-TR scheme without BGS . Data acquisition at each time point consists of presaturation (Sat.), and control or label modules (LD) followed by data acquisition (Acq.). ASL dynamics data are acquired by changing the LD and PLD in each session. b) The BGS timing optimization for the short and long time point acquisition. Four BGS pulses are inserted in LD and PLD. Label or control module is changed with interleaved manner (L/C to C/L) with BGS pulse insertion.
    Figure 5: Representative Volunteer case of fetal type: a) 4D MRA (separate acquisition) and b) 4D perfusion results with background suppression, and c) ATT and CBF map calculated from the individual timepoints in 4D perfusion. The left and right ATT difference in PCA territory is indicated by 4D-MRA (white arrows). In the ASL dynamic, the flow signal is increased earlier in the left PCA territory compare to the right PCA territory (yellow allows). The ATT map shows longer ATT in the right PCA territory (red arrow). These observations are consistent with the 4D-MRA findings.
  • Clinical application of ASL-based non-invasive perfusion territory mapping and time-resolved angiography in cerebrovascular diseases
    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 Sollmann1,7, and Hans Liebl1
    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
    Non-invasive vascular territory mapping and time-resolved angiography based on super-selective arterial spin labeling (ASL) with automated planning are clinically applicable and highly promising to improve diagnostics in cerebrovascular diseases (CVD)
    Figure 4: Angiography of a patient with moyamoya disease. Non-invasive time resolved angiography by 4D-sPack of R-ICA (red) and L-ICA (cyan) are shown in axial view with maximum intensity projections (A; top row). The non-invasive angiogram at t=2000 ms is compared to conventional DSA in coronal and sagittal view for R-ICA and L-ICA, respectively (B; red & cyan boxes). Note 4D-sPack can even depict small distal collateral vessels originating from R-ICA in agreement with DSA (B; arrows) as well as delayed perfusion by L-ICA (A; circles) in agreement with prolonged time-to-peak (TTP; C).
    Figure 2: Angiography and perfusion in a patient with left-ICA dissection, left-M1 occlusion and hypoplastic right-VA. Contrast-enhanced MR neck-angiography (A) in an axial cut shows the cerebral blood supply by R-ICA (red) and L-VA only (yellow; B). CBF is only slightly decreased in the left posterior hemisphere (circles, C), but with substantially prolonged perfusion delay (D) in this L-VA territory, as depicted by ss-ASL (E). The right-ICA widely supplies the contralateral hemisphere (E) with takeover of the left anterior and media territories as demonstrated by 4D-sPack (F).
  • Application of MRI-based oxygen extraction fraction mapping in ischemic stroke
    Di Wu1 and Shun Zhang1
    1Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
    In ischemic stroke, 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.
    Figure 2. OEF of the infarcted area defined on DWI and contralateral mirror area and their quotient (rOEF) in four ischemic stroke phases. (a) OEF significantly reduced compared with the contralateral mirror area in all four stroke phases (two-tailed paired-t test, p < 0.05 for all). Besides, OEF showed a trend of decrease from acute to chronic phase and was statistically significant (ANOVA, p = 0.022). (b) rOEF showed the same decreasing tendency with OEF (ANOVA, p = 0.024). The center line is the mean and the other two lines are standard deviation; *p < 0.05, **p < 0.01, ***p < 0.001.
    Figure 3. OEF and rOEF of initial diffusion lesion, mismatched area and final infarct among different phases in the 8 patients whose final infarct volume was smaller than initial diffusion lesion according to longitudinal MR scans. OEF (a) and rOEF (b) of the final infarct showed a trend of decrease with time, while those of the initial diffusion lesion and the mismatched area increased. Note that only increasing trend of OEF of the mismatched area reached statistical significance (repeated measures ANOVA, p = 0.022).
  • Prediction of Wallerian Degeneration in the Corticospinal Tract after Cerebral Ischemic Stroke: A Pilot APT and DWI Study
    junxin wang1, yanwei Miao1, and Jiazheng Wang2
    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).
    Fig.1 (A,D,G) DWI, (B,E,H) FLAIR, and (C,F,I) FLAIR+APTw images of an ischemic stroke patient (female; 56 years old; left limb inactivity for 15 days). DWI images demonstrated that the patient developed an acute infarction of right frontal parietal lobe cerebral infarction. The APTw intensities in regions of the ipsilateral of the ischemic lesion (black arrow) were higher than the contralateral side in both levels of posterior limb of internal capsule and cerebral peduncle. DWI and FLAIR images show no difference between two sides of the two levels.
    Table1
  • Assessment of Symptom Onset Time in Ischemic Stroke Patients Using Fast High-Resolution 3D 1H-MRSI
    Zengping Lin1, Tianyao Wang2, Rong Guo3,4, Yudu Li3,4, Yibo Zhao3,4, Tianxiao Zhang1, Jun Liu2, Xin Yu5, Zhi-Pei Liang3,4, and Yao Li1
    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
    The NAA concentration within the ischemic lesion imaged using fast high-resolution 3D MRSI decreased in a time-dependent manner after stroke onset, which might provide a useful metabolic biomarker for assessment of symptom onset time.
    Figure 1. Multimodal images from representative patients at 2.25 to 92.73 hours after ischemic stroke. The color bar for MRSI shows NAA or lactate level in institutional units. The NAA signal reduction was visible within the lesion area and decreased with time.
    Figure 3. (a) Significant reduction of NAA was observed for acute stage patients from within to over 9h window (p < 0.05), but lactate showed no significant difference. (b) A significant negative correlation between NAA and time after onset was found, but not for lactate.
  • Prediction of the Treatment Efficacy of Patients with Subacute Cerebral Infarction using the Heterogeneity of APT-weighted Signals
    Yuhan Jiang1, Peipei Chang1, Yingqiu Liuyang1, Bingbing Gao1, Yiwei Che1, Renwang Pu1, Qingwei Song1, Ailian Liu1, Zhiwei Shen2, Jiazheng Wang2, and Yanwei Miao1
    1the First Affiliated Hospital of Dalian Medical University, Dalian, China, 2Philips Healthcare, Beijing, China
    In this study, we investigated the change of APTwmax-min signals in the ischemic regions in the subacute infarction, and elucidated the relationship with ∆NIHSS score. Results showed the APTwmax-min signal was inversely correlated with ∆NIHSS score.
    Fig 1 A 56-year-old female with a subacute infarction 78 hours after the onset. a: DWI shows the hyperintense infarct area near the right lateral ventricle. b: The infarct area was low perfusion on the CBF image with 1.5 PLD. c: The infarct area was slightly hypointense on the APTw image. d: DWI-CBF fusion map shows the IC and IP. The ROI of the IC (white line) and the IP (orange line) is indicated. e: DWI-APTw fusion map. The ROI was copied from the DWI-CBF fusion map.
    Fig 3 Association between APTwmax-min signal in and ∆NIHSS score in IC and IP. (a) The APTwmax-min within IC was inversely correlated with the ∆NIHSS score (R2 = 0.184, P = 0.041). (b) The APTwmax-min within IP showed negative correlation with ∆NIHSS scores (R2 = 0.255, P = 0.014).
  • Functional Reorganization associated with Language Recovery after Repetitive Transcranial Magnetic Stimulation in Chronic Aphasic Stroke
    Bing-Fong Lin1, Po-Yi Tsai2, and Chia-Feng Lu1
    1Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan, 2Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei, Taiwan
    This study reported the efficacy of rTMS for improving language functions and inducing functional reorganization in aphasia patients. The individual lesion location and size may determine the functional circuits related to the language improvement after the inhibitory rTMS treatment.
    Figure 3. Scatter plots with significant correlations (|r|>0.65, p<0.05) between change scores of language performance and FCs of brain regions.
    Figure 2. Hierarchical clustering based on the profiles of overlapping percentage between stroke lesion and the selected cortex. The right-hand side of each row shows patient label (by a given number) and the corresponding lesion size. The columns are the selected brain regions related to the language network. The color represents the values of z-scores (red for positive, and green for negative value). The patients are clustered into four aphasia subtypes based on lesion patterns, including Broca and mixed type, unspecified, putamen, and Wernicke aphasia.
  • Longitudinal Changes in Neurometabolite Levels from Acute to Subacute Stroke: A Pilot Study Using Fast High-resolution 3D 1H-MRSI
    Bin Bo1, Tianyao Wang2, Rong Guo3,4, Yudu Li3,4, Yibo Zhao3,4, Tianxiao Zhang1, Zengping Lin1, Ziyu Meng1, Jun Liu2, Xin Yu5, Zhi-Pei Liang3,4, and Yao Li1
    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
    We performed fast high-resolution 3D MRSI in a longitudinal cohort of ischemic stroke patients. Temporal changes of different neurometabolites from acute to subacute stroke were observed in different regions within the hypoperfused tissue.
    Figure 2. Multimodal images from representative patients at acute and subacute stages after ischemic stroke. All the images were registered to the structural T1-weighted images. The color bar for ASL-PWI shows the cerebral blood flow in ml/100g/min. The color bar for MRSI shows NAA or lactate level in institutional units.
    Figure 3. Group comparison of mean relative NAA and lactate concentrations for different regions of interest in acute and subacute stroke patients, respectively (Error bars, 95% confidence interval). *p < 0.05, **p < 0.01.
  • Clinical Research of Multi-modal MRI in Ischemic Stroke: Cerebral Oxygen Extraction Fraction, Nonblood Susceptibility and Blood Flow
    Di Wu1, Shun Zhang1, and Weiyin Vivian Liu2
    1Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China, 2MR Research, GE Healthcare, Beijing, China, Beijing, China
    Difference of CBF was found between patients with and without penumbra. The OEF and nonblood susceptibility of tissue in the penumbra were significantly different from ischemic core. OEF in the diffusion lesion was correlated with clinical severity and continuously decreased with time.
    Figure 2. Oxygen extraction fraction (OEF, A), nonblood susceptibility (B) and cerebral blood flow (CBF, C) in the perfusion lesion (PL), penumbra and diffusion lesion (DL) of the mismatched group. Significant differences of OEF and nonblood susceptibility were found between DL and PL and between DL and penumbra. There were no significant differences of CBF among PL, DL and penumbra.
    Figure 1. Representative images of three patients in the corresponding groups classified by DEFUSE 3 criteria. (A) A 64-year-old female with the volume of diffusion lesion (shown in green on ADC maps) matched with that of perfusion lesion (shown in red on CBF maps). (B) A 50-year-old male whose perfusion lesion was rather larger than the diffusion lesion. (C) A 33-year-old female with re-perfused left hemisphere.
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Digital Poster Session - Oxygen, Reactivity & Tissue Function in Stroke Imaging
Neuro
Thursday, 20 May 2021 19:00 - 20:00
  • Simultaneous Oxygenation and Metabolic Imaging Relates Oxygen and Neuronal Metabolism in Acute Stroke
    Tianxiao Zhang1, Rong Guo2,3, Tianyao Wang4, Zengping Lin1, Yudu Li2,3, Yibo Zhao2,3, Jun Liu4, Danhong Wu5, Zheng Jin6, Xin Yu7, Zhi-Pei Liang2,3, and Yao Li1
    1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China, 2Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 3Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 4Radiology Department, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China, 5Neurology Department, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China, 6Shanghai Minhang Hospital of Integrated Traditional Chinese and Western Medicine Hospital, Shanghai, China, 7Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
    We performed high-resolution simultaneous measurements of brain oxygenation and metabolism in acute stroke. Our results showed not only the expected changes in the markers of oxygenation and neurometabolites individually, but also their concurrent coupling.
    Figure 1. Simultaneous 3D brain neurometabolites and OEF mapping for an acute ischemic stroke patient. (A, B) 3D NAA and Lac map in triplanar views overlaid on T1-weighted images. The representative spectra were from the DWI lesion (red), infarct growth (blue) and contralateral normal (light green) regions, respectively. (C) 3D venous OEF map in triplanar views overlaid on QSM images. (D) 3D quantitative map in triplanar views. (E) Timeline of the experimental study.
    Figure 4. Significant correlations between values and lactate or lactate to NAA ratio concurrently detected in infarct growth area (A) but not in infarct core (B) of acute ischemic stroke patients.
  • A Shearlet-based whole brain vein segmentation algorithm and its application for the detection of regional differences in venous oxygenation
    Sina Straub1, Janis Stiegeler1,2, Edris El-Sanosy3, and Till M. Schneider4
    1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany, 3Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 44Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany
    Compared with a ground truth, the proposed vein segmentation algorithm can accurately segment venous vasculature and allows for a susceptibility-based differentiation of deep and superficial vascular territories.
    Figure 3: Representative axial and sagittal slices of 16-slices minimum intensity projections of tSWI data and segmentations. The manually segmented ground truth is shown in green, overlaid with (from left to right) the segmentation from the proposed algorithms for a multi-echo acquisition when R2* is available, without R2*, and for the Frangi method, respectively. These segmentations are shown in red so that true positives appear orange, false positives red, and false negatives green.
    Figure 1: Algorithm flowchart summarizing the main steps 1-6 of the algorithm (the use of R2* data is omitted).
  • A Flexible Computational Framework for Characterization of Dynamic Cerebrovascular Response to Global Hemodynamic Stimuli
    Siddhant Dogra1, Xiuyuan Wang2, Jelle Veraart3, Alejandro Gupta3, Koto Ishida3, Deqiang Qiu4, and Seena Dehkharghani3
    1Radiology, New York University Langone Health, New York, NY, United States, 2Weill Cornell, New York, NY, United States, 3New York University Langone Health, New York, NY, United States, 4Emory University, Atlanta, GA, United States
    A custom pipeline employing spatial and temporal denoising permits for enhanced dynamic CVR analysis in patients with chronic steno-occlusive disease to uncover otherwise concealed dynamic features of the ACZ-augmented BOLD cerebrovascular response.
    Sample BOLD signal (A, B) and representative CVRend and CVRmax maps (C) from a patient with right hemisphere disease. % BOLD-signal changes of a right hemispheric voxel with 30-second temporal delay with respect to the straight sinus time series shown from raw (gray) and processed signals (orange) demonstrating non-monotonic post-ACZ effects. Panel B demonstrates a case with CVRmax greater than CVRend. Panel C demonstrates challenges with CVRend evaluation confounding essentially preserved, symmetric CVRmax augmentation in a patient remaining stable during serial follow-up.
    Sample BOLD signal (A, B) and representative CVRend and CVRmax maps (C) from a patient with right hemisphere disease. % BOLD-signal changes of a right hemispheric voxel with 30-second temporal delay with respect to the straight sinus time series shown from raw (gray) and processed signals (orange) demonstrating non-monotonic post-ACZ effects. Panel B demonstrates a case with CVRmax greater than CVRend. Panel C demonstrates challenges with CVRend evaluation confounding essentially preserved, symmetric CVRmax augmentation in a patient remaining stable during serial follow-up.
  • Relationship of FLIAR vascular hyperintensity territory with APCVs and venous oxygen saturation in patients with cerebral infarction
    Pei-pei chang1, Yan-wei Miao1, Yu-han Jiang1, Yi-wei Che1, Bing-bing Gao1, Li-hua Chen1, Qing-wei Song1, Ren-wang Pu1, Ai-lian Liu1, Liang-jie Lin2, and Jia-zheng Wang2
    1The First Affiliated Hospital of Dalian Medical University, Da Lian, China, 2Philips Healthcare, Bei Jing, China
     Patients with severe-occlusion were associated with higher FVH and APCVs scores than those with mild-to-moderate stenosis. The FVH territory was observed to be positively correlated with APCVs territory, oxygen extraction in patients with cerebral infarction.
    Figure.4 MRI images of a 63-years-old man. A: the MR angiography shows the occur of occlusion in left middle cerebral artery. B: DWI shows the hyperintense region in left basal ganglia. C~F: The modified ASPECT score of FVH shows that the FVH score was 6. G~I: APCVs score is 5.
    Tables Clinical information and MR measurements for patients
  • A Local Linear Regression Algorithm for Partial Volume Correction in Brain Oxygen Extraction Fraction Estimation
    Yasheng Chen1, Chunwei Ying2, Peter Kang1, Slim Fellah1, Amy Mirro3, Melanie Fields3, Kristin Guilliams1, Jin-Moo Lee1, Andria Ford1, and Hongyu An4
    1Neurology, Washington University School of Medicine, St. Louis, MO, United States, 2Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States, 3Pediatrics Hematology, Washington University School of Medicine, St. Louis, MO, United States, 4Washington University School of Medicine, St. Louis, MO, United States
    We developed a local linear regression based partial volume correction (PVC) method for OEF estimation. The PVC OEF method reduced model fitting errors and signal contamination of CSF, and it improved the association between OEF and WMH lesion burden.
    Figure 2. The group average rOEF maps without (A) and with (B) PVC, and the group average fitting error maps without (C) and with (D) PVC.
    Figure 3. Correlation between WM rOEF and rVWMH with and without PVC (A, B), and correlation between watershed rOEF and rVWMH with and without PVC (C, D).
  • Predicting the Neurodegeneration after Stroke using Disconnectivity Map
    Takayuki YAMAMOTO1, Hikaru FUKUTOMI1, Vincent DOUSSET1,2, Igor SIBON3, and Thomas TOURDIAS1,2
    1Institut de Bio-imagerie IBIO, Université de Bordeaux, Bordeaux, France, 2Neuroimagerie diagnostique et thérapeutique, CHU de Bordeaux, Bordeaux, France, 3Unité de soins intensifs neurovasculaires, CHU de Bordeaux, Bordeaux, France
    We investigated the relation between stroke and remote consequences using probability maps of damaged tractograms. We demonstrated that such disconnectivity approach can successfully predict regions that will degenerate and show long term iron accumulation.

    Figure 1. Overview of a representative disconnectivity map. Disconnectivity map (green) is calculated using the lesion mask of the infarction (red), based on the tractograms of healthy subjects. The degree of overlap of the disconnectivity map and masks of deep nuclei was used to estimate the remote effect of the infarction.

    Figure 3. Voxel-based morphometry analysis for the R2* value in the substantia nigra and the thalamus. The red area means a significant increase of the R2* value at 1-year follow-up compared with that at baseline. The blue area means a significant decrease at 1-year follow-up.

  • Revisit on the cerebrovascular responses to end-tidal CO2 fluctuations during spontaneous breathing as a surrogate of regional cerebrovascular reactivity assessment under hypercapnic challenge
    Suk-tak Chan1, Karleyton C. Evans2, Tian-yue Song1, Andre van der Kouwe1, Bruce R. Rosen1, Yong-ping Zheng3, and Kenneth K. Kwong1
    1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Biogen, Inc., Cambridge, MA, United States, 3Department of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong
    CVR to endogenous CO2 at rest showed significant inter-subject variability and was substantially different from CVR to external CO2 challenge. Such inter-subject variability, not reduced by correction of respiratory effects, also showed up less prominently in CVR to endogenous O2 at rest.
    Fig 1. Individual CVR maps show significant CVR changes under external CO2 challenges (n=11) (1st row). Individual CVR maps to endogenous maps showed significant inter-subject variability (2nd row). Such inter-subject variability was not reduced by correction of respiratory effects using RETROICOR (3rd row). CVR maps to endogenous O2 show less inter-subject variability than CVR maps to endogenous CO2 (4th row).
  • Distinct Effects on Cognition Caused by the Side of Asymptomatic Carotid Artery Stenosis
    Jyun-Ru Chen1, Chun-Jen Lin2,3, I-Hui Lee2,3,4, and Chia-Feng Lu1
    1National Yang-Ming University, Taipei, Taiwan, 2School of Medicine, National Yang-Ming University, Taipei, Taiwan, 3Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, 4Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
    The correlation between the side of asymptomatic internal carotid stenosis (aICS) and cognitive impairment was less explored. In this study, significant difference of functional connectivity (FC) and correlations between FC and cognitive symptoms were found between the two aICS groups.
    Figure 2 The mean FC matrices for the aICSL (upper-left matrix) and aICSR (upper-right matrix) groups during the resting state. The significant differences between two groups are displayed in the lower matrix. A positive t value (yellow) represents a higher FC in the aICSR group compared to that in the aICSL group. Mot.: Motor; Lim.: Limbic; Vis.: Visual; Sen.: Sensory; Sub.: Subcortical; Tem.: Temporal; Cer.: Cerebellum.
    Figure 3 Scatter plots for the significant correlations between functional connectivity and neuropsychological assessments during the resting state.
  • Agreement of CVR maps acquired using hypocapnic and hypercapnic breathing tasks
    Kristina M. Zvolanek1,2, Rachael C. Stickland2, Stefano Moia3,4, Apoorva Ayyagari1,2, César Caballero-Gaudes3, and Molly G. Bright1,2
    1Biomedical Engineering, Northwestern University, Evanston, IL, United States, 2Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States, 3Basque Center on Cognition, Brain and Language, Donostia, [Gipuzkoa], Spain, 4University of the Basque Country EHU/UPV, Donostia, [Gipuzkoa], Spain
    Our results demonstrate comparable BOLD cerebrovascular reactivity (CVR) and hemodynamic lag measurements between breath-hold and deep breathing tasks, suggesting that the two tasks can be used interchangeably in healthy participants.
    Voxelwise maps of the Bland-Altman analysis showing mean difference between breath-hold (BH) and cued deep breathing (CDB) cerebrovascular reactivity (CVR) across all subjects. Differences in non-optimized CVR (No-Opt) are shown on the left, lag-optimized on the right, with thresholded maps for each in the bottom row (p<0.05). Negative values represent voxels with greater BH CVR than CDB CVR, and vice versa. Significant differences appear primarily at brain edges and in white matter.
    Voxelwise correlations between breath-hold (BH) and cued deep breathing (CDB) cerebrovascular reactivity (CVR) before lag optimization (No-Opt), lag-optimized CVR (Lag-Opt), and lag. A Fisher's Z transform was performed on individual subject correlations to calculate a group average. All single subject Fisher’s Z values are significantly different from 0 at an alpha-level of 0.05 (Z>0.0232).
  • Effect of Myelin Content on Cognitive Outcomes in Cerebral Small Vessel Disease
    Elizabeth Dao1, Roger Tam1, Ging-Yuek R Hsiung1, Lisanne ten Brinke1, Rachel Crockett1, Cindy K Barha1, Youngjin Yoo1, Walid al Keridy2, Stephanie H Doherty1, Alex L MacKay1, Cornelia Laule1, and Teresa Liu-Ambrose1
    1University of British Columbia, Vancouver, BC, Canada, 2King Saud University, Riyadh, Saudi Arabia
    Lower normal appearing white matter myelin water fraction was associated with slower processing speed and poorer working memory in people with cerebral small vessel disease, after accounting for age, education, and white matter hyperintensity volume.
    Figure 1 A) PD-weighted scan for WMH segmentation; B) T2-weighted scan for white matter hyperintensity segmentation; C) white matter hyperintensity mask; D) myelin water fraction map; E) normal appearing white matter myelin water fraction mask; F) normal appearing white matter myelin water fraction map

    Table 2 Multiple Linear Regression Results

    Independent Variables in Step 1 = age and education; Independent Variables in Step 2 = age, education, and white matter hyperintensity volume; Independent Variables in Step 3 = age, education, white matter hyperintensity volume, and normal appearing white matter (NAWM) myelin water fraction (MWF)

    *Significant at p ≤ 0.05

  • Impaired cerebrovascular reactivity in patients with Huntington's disease
    Suk-tak Chan1, Nathaniel Mercaldo2, Kenneth K. Kwong1, Steven M. Hersch3, and Herminia D. Rosas3
    1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Department of Radiology, Massachusetts General Hospital, Boston, MA, United States, 3Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
    Alterations in cerebrovascular function was found in HD and the dominance of such alterations in white matter further suggests the signs of small vessel disease. The impaired cerebrovascular reactivity may be an important, not as yet considered, contributor to early neuropathology in HD. 
    Figure 1. Group comparison of cross-correlation of ΔBOLD with PETCO2 between HD subjects and healthy controls after adjusting for age, corrected at pfdr<0.05. Cold colors represent weaker cross-correlation in HD subjects when compared with controls.
    Figure 2. Map of delayed BOLD responses to increased PETCO2 in a representative HD subject. The magnitude of time delay in BOLD responses relative to PETCO2 increases from cold colors to warm colors.
  • Quantification of Relative Blood Volume in Squirrel Monkey Brain in vivo using an MRI-based template
    Zhangyan yang1,2, Feng Wang1,3, Chaohui Tang1, Li Min Chen1,3, and Gore C. John1,2,3
    1Institute of Imaging Science, Vanderbilt University, Nashiville, TN, United States, 2Biomedical Engineering, Vanderbilt University, Nashiville, TN, United States, 3Department of Radiology and Radiological Science, Vanderbilt University, Nashiville, TN, United States
    High resolution maps of rCBV provide information for studies of brain function and changes in brain. In this study, by using a contrast agent in non-human primates, we quantified rCBV maps, identified alterations of rCBV across regions, and created an rCBV atlas using a brain template.
    Figure 1. Registration pipeline of VALiDATe29 squirrel monkey atlas labels (template space) to structural images before MION (subject space). T2* weighted image before MION administration were first skull stripped and down sampled to template size. Then the template image was transformed into subject space by performing affine linear automatic image registration (AIR) followed by non-linear LDDMM registration. Inverse transformation matrices were subsequently applied to the template labels. Labels are transformed to subject space and checked visually using MRICroN.
    Figure 2. (a) Characteristic rCBV map of one subject. The 13th slice is shown. (b) structural T2* image before MION overlayed with transformed labels in subject space for the same slice. Structural image is in gray scale and labels are indicated in different color. (c) label names, the label numbers are consistent with numbers in b.
  • Test–Retest Repeatability of Brain Oxygen Metabolism Measurement using MRI
    Chunwei Ying1, Michael M. Binkley2, Peter Kang2, Yasheng Chen2, Jin-Moo Lee2,3, Andria L. Ford2, and Hongyu An3
    1Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States, 2Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States, 3Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, United States
    Background suppressed 3D pCASL had better test-retest repeatability than 2D pCASL, especially in watershed region. OEF measured with ASE had better repeatability than CBF measured with pCASL.  CMRO2 had similar test-retest repeatability to CBF.
    Figure 4. Inter-session repeatability of OEF, CBF and CMRO2 in WB, GM, WM and WS regions. The red horizontal line, dotted black horizontal lines, and solid black horizontal lines represent the mean, ± SD, and ± 1.96xSD of inter-session measurement differences, respectively.
    Figure 2. Gray matter (A), white matter (B) and watershed region mask (C), OEF map (D), CBF maps (E) and corresponding CMRO2 maps (F) from a representative subject.
  • Detecting Magnetic Resonance Changes in Brain Structure and Function During Stroke Rehabilitation
    Jonathan Taylor1, Oun Al-iedani2,3, Saadallah Ramadan3,4, Neil Spratt1, and Sarah Valkenborghs5
    1School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia, 2School of Health Sciences, University of Newcastle, Newcastle, Australia, 3Hunter Medical Research Institute, Newcastle, Australia, 4Faculty of Health and Medicine, University of Newcastle, Newcastle, Australia, 5University of Newcastle, Newcastle, Australia

    Using Magnetic Resonance (MR) data acquired as part of a feasibility study in stroke rehabilitation, a novel post-processing pipeline was designed and implemented to explore metabolic factors with MR Spectroscopy (MRS).

    Figure 3: Whole brain segmentation at baseline clockwise from top left, GM, WM, lesion, and CSF. Lesion segmentation processed in SPM software; others processed by FSL-FAST. Two-dimensional transverse view of a three-dimensional binary mask. Lesion segmentation algorithm tends to categorise large CSF volumes as lesion, visible at first and second ventricles.

    Figure 1i: inSPECT GUI displaying list of selectable metabolites (B), the configuration panel (A) Cramer-Rao lower bounds SD% threshold. Output panel (C) contains the button to execute processing of data, the lower edge (D) is the status bar, indicating a single CSV file has been opened.

    Figure 1ii: inSPECT GUI with voxel selection tab active (B) with voxels checked for filtering. (A) is selected file information and checkboxes for inputting the concentration filter method. Panel (C) is the Save & Execute button, panel (D) is current status, a Baseline Segmentation file has been loaded.

  • Processing cerebrovascular reactivity data using shift-invariant dictionary learning
    Emilie Sleight1,2, Michael S Stringer1,2, Ian Marshall1,2, Joanna M Wardlaw1,2, Sotirios A Tsaftaris3, and Michael J Thrippleton1,2
    1Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom, 2UK Dementia Research Institute, Edinburgh, United Kingdom, 3Institute for Digital Communications, University of Edinburgh, Edinburgh, United Kingdom
    We introduce a new processing method for cerebrovascular reactivity (CVR) data known as shift-invariant dictionary learning (SIDL). We show that measurements of CVR magnitude and CVR delay obtained with SIDL are comparable to standard processing.
    Figure 2. Comparison of CVR magnitudes (A) and delays (B) obtained with SIDL and GLM. The outliers are labelled as outlier 1 and 2.
    Figure 3. EtCO2, mean BOLD in deep grey matter and kernel of a subject with comparable estimates to GLM and of the two outliers.
  • Cerebral circulation time related DMN connectivity in intracranial dural arteriovenous fistula before and after treatment
    Bejoy Thomas1, Jithin S S1, Sabarish S Sekar1, Santhosh Kannath1, and Ramshekhar N Menon2
    1Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India, 2Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India
    This study explores the relationship between cerebral circulation time and rsfMRI network alterations related to cognitive decline in dural arteriovenous fistula patients and their reversibility after embolisation therapy.
    Connectivity analysis: ROI to ROI, Low circulation time > Healthy control
    Connectivity analysis: ICA, Low circulation time > Healthy control
  • fMRI based evaluation of yoga-induced changes in ischemic post-stroke patients
    Rama Jayasundar1, Dushyant Kumar1, Rajesh Mishra1, Priyanka Jain2, Jaideep Sachdeva3, Chahat Kumar1, Priyanka Bhagat4, and Padma Srivastava4
    1Department of NMR, All India Institute of Medical Sciences, New Delhi, India, 2Centre for Development of Advanced Computing, New Delhi, India, 3Manipal University, Jaipur, India, 4Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
    Stroke is a debilitating  disease with long term effects. With increasing interest in use of yoga in post-stroke recovery, this fMRI study has demonstrated increase in the BOLD activity in the left pre-central gyrus region in ischemic stroke patients, 3 and 6 months post-yoga intervention.
    Figure 1: Longitudinal changes in the National Institutes of Health Stroke Scale (NIHSS) scores in ischemic stroke patients subjected to yoga intervention.
    Figure 2: Representative frequency distribution of the BOLD activity from a left hemisphere ischemic stroke patient. The purple peak corresponds the zero time point (pre-intervention), the red to 3 months post-intervention and green to 6 months post-intervention.
  • Clinical Phenotype Polymorphism of Ischemic Stroke Underpinned by Inter-network Functional Connectivity
    Lijuan Zhang1, Siqi Cai1,2, Chunxiang Jiang1,2, Shihui Zhou1,2, and Li Yi3
    1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2University of Chinese Academy of Sciences, Beijing, China, 3Peking University Shenzhen Hospital, Shenzhen, China
    Divergent inter-network connectivity patterns were identified in stroke patients with unilateral motor deficit, indicating a polymorphism of the clinical phenotype of stroke. This study provides new insight into better itemization of the disease dynamic and management of ischemic stroke.
    Functional connectogram (A-C) and group averaged functional connectivity (FC) matrix (D-F) of healthy controls (HC) and two clusters of subjects with stroke. Asterisk (*) indicates significant differences between the patient clusters (Two-sample t-test, p<0.05, FDR correction). Comment sign (#) indicates significant difference between either cluster and HCs (Two-sample t-test, p<0.05, FDR correction).
  • Monte Carlo Simulation Study of Asymmetric Spin Echo and Preliminary Estimation of Vessel Size Index
    Jian Shen1 and John Wood1,2
    1University of Southern California, Los Angeles, CA, United States, 2Children's Hospital Los Angeles, Los Angeles, CA, United States
    The OEF estimated by ASE method might be affected by the diffusion effect and it mainly applies to bigger vessels. We also demostrate the feasibility to generate the VSI map from ASE data.
    Figure 1. Representative signal decay curve (left) and Monte Carlo simulation system (right).
    Figure 3. Typical VSI map for a SCD patient (left) and mean VSI for all the subjects (right).
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Digital Poster Session - Flow, Diffusion & Preclinical Modelling in Stroke Imaging
Neuro
Thursday, 20 May 2021 19:00 - 20:00
  • Exploring the effect of aquaporin-4 suppression on cell membrane water exchange in a mouse model of brain ischemia using diffusion-weighted MRI
    Takuya Urushihata1, Hiroyuki Takuwa1, Manami Takahashi1, Yasuhiko Tachibana2, Jeff Kershaw2, Nobuhiro Nitta2, Sayaka Shibata2, Masato Yasui3, Makoto Higuchi1, and Takayuki Obata2
    1Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, QST, Chiba, Japan, 2Applied MRI Research, National Institute of Radiological Sciences, QST, Chiba, Japan, 3Keio Advanced Research Center for Water Biology and Medicine, Keio University, Tokyo, Japan
    Comparison of aquaporin-4 knockout and wild-type mice using multi-b-value multi-diffusion-time DWI detected different ADCs and water exchange-time for ischemic and healthy tissue.
    Fig. 1. (A) Typical T2-weighted (T2W) and diffusion-weighted images (DWI) for wild-type (WT) and AQP4 knockout (AQP4-KO) mice. The left side of the brain had a middle cerebral artery occlusion. (B) and (C) Normalized b-value dependent signal decay for the ipsilateral (B) and contralateral (C) sides at different diffusion times (Δ = 40, 70 and 100 ms). Solid lines indicate WT mice (closed circles with SD bars) and broken lines indicate AQP4-KO mice (white circles with SD bars).
    Fig. 3. (A) Typical apparent diffusion coefficient (ADC) maps of wild-type (WT, top) and AQP4 knockout (AQP4-KO, bottom) mice focused on the ipsilateral region at Δ =70 ms. The ADC in the ischemic region has a range of 0 – 5×10-4 mm2/s. (B) The bar graphs show the mean ADC of WT (white) and AQP4-KO (black) mice for each b-value range and Δ. The error bars correspond to the SD over animals. The results of Two-way ANOVA are shown in the table at the base of the figure.
  • Accuracy of Intravoxel Incoherent Motion (IVIM) for quantification of perfusion-diffusion mismatch in Acute Stroke.
    Mira Liu1, Yong Jeong1, Gregory Christoforidis1, Niloufar Saadat2, Steven Roth3, Marek Niekrasz1, and Timothy Carroll1
    1The University of Chicago, Chicago, IL, United States, 2Northwestern University, Chicago, IL, United States, 3University of Illinois at Chicago, Chicago, IL, United States
    A retrospective validation study of quantitative intravoxel incoherent motion (IVIM) in a canine model found excellent agreement of IVIM and reference standard perfusion and diffusion values over a range of physiologic conditions: normocapnia, hypercapnia, and post-occlusion.

    Figure 1: Shown on the left are quantitative DSC CBF (A,B,C) and quantitative IVIM perfusion (D,E,F) images at normocapnia, hypercapnia, and post-occlusion. On the right is a standard ADC map (G) compared to IVIM diffusion coefficient image (H) post-occlusion.

    Figure 2: Correlations of quantitative IVIM perfusion and DSC qCBF to neutron-capture microspheres at normocapnia, hypercapnia, and post-occlusion hemispherically. The correlation suggests comparable agreement between IVIM and neutron-capture microspheres as standard quantitative DSC CBF.
  • Central pulse pressure and its influence on carotid artery morphology predict white matter hyperintensity volumes
    Andrew Crofts1, Jessica J Steventon2, Joseph R Whittaker3, Marcello Venzi1, Hannah L Chandler4, Mahfoudha Al Shezawi5, Eric J Stohr6, Chris Pugh6, Barry McDonnell6, and Kevin Murphy1
    1Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom, 2CUBRIC, School of Medicine, Cardiff University, Cardiff, United Kingdom, 3Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 4CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom, 5Cardiff Metropolitan University, Cardiff, United Arab Emirates, 6Cardiff Metropolitan University, Cardiff, United Kingdom
    Central pulse pressure and its influence on carotid artery morphology better predict white matter hyperintensity volume than both brachial blood pressure and pulse wave velocity, a measure of arterial stiffness.
    Figure 3: Example image showing large white matter hyperintensities (blue) overlaid on the subject’s FLAIR image. The total white matter hyperintensities volume for this subject was 13406 voxels.
    Figure 4: Example image showing the left carotid artery from the same subject as Figure 3. The colour map shows the arterial radius (average across the vessel = 2.9470). The tortuosity for this vessel was 0.8773.
  • Changes in Functional Connectivity and Cognition in HIV Infected Individuals with  Cerebral Small Vessel Disease
    Kyle Douglass Murray1, Alan Finkelstein1, Miriam Weber1, Jianhui Zhong1, and Giovanni Schifitto1
    1University of Rochester, Rochester, NY, United States
    In this work, we show cognitive and functional changes in the brains of HIV-infected individuals with cerebral small vessel disease using a graph theoretical analysis. Correlations of cognitive scores and imaging metrics imply potential compensatory effects of functional brain networks.
    Figure 4. Subcortical associations with Node Degree. A. Boxplots of HIV group differences for each subcortical structure. B. Scatterplots showing Node Degree as a function of Motor Z-score for each region corresponding from A Spearman’s rho is displayed for each cohort. Note that only regions with significant cohort differences are shown. {* p < 0.05; ** p < 0.01}
    Figure 3. Global graph theory metric group differences between cohorts. A. by HIV-status using all subjects. B. by HIV-status stratified by CSVD-status. CSVD+ is defined by a subject receiving any Fazekas score greater than zero.
  • Is Arterial Spin Labeling Effective in Measuring Cerebrovascular Reactivity? A Test-retest Study on Impact of Labeling Efficiency
    Taghi Rostami1, Moss Y Zhao2, Audry P Fan3, David Yen-Ting Chen4, Magdalina J Sokolska5, Jia Guo6, Yosuke Ishii7, David D Shin8, Mohamad Mehdi Khalighi2, Dawn Holley2, Kim Halbert2, Andrea Otte2, Brittney Williams2, Jun-Hyung Park2, Bin Shen2, and Greg Zaharchuk2
    1Bioengineering, Stanford University, Stanford, CA, United States, 2Radiology, Stanford University, Stanford, CA, United States, 3Medical Imaging, UC Davis, Davis, CA, United States, 4Taipei Medical University, Taipei, Taiwan, 5University College London Hospitals, London, United Kingdom, 6University of California Riverside, Riverside, CA, United States, 7Tokyo Medical. and Dental University, Tokyo, Japan, 8GE Healthcare, Menlo Park, CA, United States
    Single- and multi-PLD arterial spin labeling (ASL) MRI before and after vasodilation in 15 normal subjects showed that both labeling techniques achieved high repeatability (within-subject Coefficient of Variance pre-ACZ: 0.82 and 1.23%, and post-ACZ: 0.51 % and 1.00%).
    Figure 5. (A) Within-Subject Coefficients of Variance for both single (left) and multi-PLD (right) PCASL pre and post-ACZ were much closer to 0% than 100%, which are indicative of repeatability. (B) Intraclass Correlation Coefficients for both single (left) and multi-PLD (right) PCASL pre and post-ACZ were much closer to 1 than 0, which are indicative of repeatability.
    Figure 4. (A) Mean labeling efficiency for single-PLD ASL methods increased for significantly (p=0.03) after acetazolamide injection but did not change significantly between the two sessions. (B) Mean labeling efficiency for multi-PLD ASL method increased significantly (p<0.01) after acetazolamide injection but did not change significantly between the two sessions.
  • Using diffusion microstructure distributions for prediction of motor outcomes in stroke recovery
    Anuja Sharma1, Clint Frandsen1, Ganesh Adluru1, and Edward DiBella1
    1UCAIR, Dept. of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States
    Using distribution-based measurements of diffusion microstructure improves the ability to detect subtle underlying differences. Together with baseline Fugl-Meyer scores, they significantly improve models for predicting motor outcomes in stroke patients.
    Figure 1: Probability density functions (PDFs) of Orientation Dispersion Index (ODI) values from the NODDI model 6 for all stroke patients in the PLIC region of the brain. PDFs estimated for both, ipsilesional (I) and contralesional (C) sides of the brain. The corresponding mean ODI values for each PDF are also marked on the x-axis. The baseline Fugl-Meyer Upper Extremity score (FMUE-TP1) is also indicated on top of each subplot.
    Table 1: Linear regression statistics for various models for PLIC region. Followup FMUE-TP2: response variable. Predictor variables are chosen from baseline as follows: A) Upper-left block (blue highlight): distribution-valued ODI and RDI observations (ΔDist). B) Upper-mid block: mean-based ODI and RDI observations (ΔMean). C) Upper-last column: Only FMUE-TP1. D) Lower block (green highlight): combination of FMUE-TP1 with either ODI or RDI diffusion parameters.
  • Longitudinal analysis revealed increased parenchymal free water may be relieved by revascularization surgery in patients with moyamoya disease
    Shoko Hara1,2, Masaaki Hori2,3, Yoji Tanaka1, Taketoshi Maehara1, Shigeki Aoki2, and Tadashi Nariai1
    1Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan, 2Radiology, Juntendo University, Tokyo, Japan, 3Radiology, Toho University Omori Medical Center, Tokyo, Japan
    We analyzed 13 patients with moyamoya disease before and after the revascularization surgery by multishell diffusion MRI. By NODDI and free-water imaging analysis, increased extracellular fluid showed significant decrease after the surgery.
    Figure 1. Parametrical maps of the representative case. A 19 year-old female who presented with transcient ischemic attacks of the right side received revascularization surgery (indirect bypass surgery) to the left hemisphere. Preoperative isotropic volume fraction (Viso) of NODDI and freewater fraction (FWF) of regularized bi-tensor model suggests increased water component in the left hemisphere (arrows) compared to the contralateral hemisphere. The increased water seems to decrease after the surgery (arrows).
    Parametrical values of normal controls (Normal), preoperative (Pre) and postoperative (Post) patients in six regions. Compared to normal controls, preoperative regions showed higher Viso and FWF in most regions, and significantly decreased after the surgery. In the white matter (WM) of the ACA areas, OD is higher, and FAt and FA are lower compared than normal controls. FA in the WM of MCA showed significant increase after the surgery. GM, gray matter. *P<.05 (unpaired T test) and †P<.05 (paired T test) after Bonferroni correction for six parameters.
  • Feasibility of amide proton transfer weighted imaging in the diagnosis of patients with symptomatic intracranial artery stenosis
    Kunjian Chen1, Weiqiang Dou2, Xinyi Wang1, Weiyin Vivian Liu2, Xinyu Wang1, Huimin Mao1, and Yu Guo1
    1The First Affiliated Hospital of Shandong First Medical University, Jinan, China, 2MR Research China, GE Healthcare, Beijing, China
    APTw imaging may be used as one effective method in diagnosing symptomatic intracranial artery stenosis, and provide additional clinical value on the basis of 3D-ASL imaging.
    Figure 1 A. 48-year-old male with an occlusion in the right MCA. B. 49-year-old male with severe stenosis of the left ICA C7 and L-MCA M1. (a) High APTw value area was visible (black arrow). (b) Perfusion was lower in the ipsilateral side than the contralateral side (white arrow).
    Figure 2 The ROC curve showed the sensitivity and specificity values of APT and 3D-ASL in the diagnosis of symptomatic intracranial artery stenosis. The diagnosis of combined ASL and APT(AUC=0.997, P<0.001) shows the most robust diagnostic performance in SIAS.
  • 4D Flow MRI assessment of cerebral blood flow before and after superficial temporal artery-middle cerebral artery bypass surgery
    Mingzhu Fu1, Chao Xia2, Miaoqi Zhang1, Yutao Ren2, Shuo Chen1, Rui Tian2, Yi Liu2, and Rui Li1
    1Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China, 2Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, China
     STA-MCA bypass could directly improve the cerebral blood supply without affecting the hemodynamics of other arteries, such as BA and ICA.
    Figure.1 Visual assessment of patency of STA-MCA bypass using 4D Flow MRI. Time-of flight magnetic resonance angiography (MRA) (A, B) and 4D Flow MRI (C, D) were performed preoperatively (A and C) and 7 days after bypass surgery (B and D). The yellow arrows indicated the locations of STA used to STA-MCA bypass.
    Table.2 Paired samples t- test of BFV Before and after bypass surgery.
  • Relationship between FVH and the blood perfusion, acid-base metabolism and edema in patients with acute/subacute infarction
    Pei-pei Chang 1, Yan Wei Miao1, Yu-han Jiang1, Yi-wei Che1, Bing-bing Gao1, Li-hua Chen1, Qing-wei Song1, Ren-wang Pu1, Ai-lian Liu1, Liang-jie Lin2, and Jia-zheng Wang2
    1The First Affiliated Hospital of Dalian Medical University, Da Lian, China, 2Philips Healthcare, Bei Jing, China
     The FVH score was observed positively correlated with ratio of relative CBF2.5 values and negatively correlated with ADC value in patients with acute/subacute infarction. No significant correlation was observed between the FVH score and APTw values.
    Figure 3. Relationship between the FVH score and MRI parameters in patients with cerebral infarction. The FVH score was positively correlated with rrCBF2.5, and negatively correlated with ADC value (red asterisk). No significant correlation was observed between FVH score and APTw values.
    Figure 2. Measurement of APTw values at the cerebral infarction area of an 65 patient. A: brain MR angiography showed occlusion in left middle cerebral artery. B: DWI showed a hyperintensity region in left basal ganglia. C: The DWI-APTw fusion image of showed that the signal of infarct area was lower than that of its contralateral region. D-F: a 3D ROI was delineated layer by layer for measurement for APTw values.
  • Mapping of Relative Water Exchange Index (rWEI) in Post Thrombectomy Patients
    Young Ro Kim1 and Jerrold L Boxerman2
    1Radiology, MGH, Charlestown, MA, United States, 2Neuroradiology, Brown University, Providence, RI, United States
    The relative water exchange index (rWEI) method was developed and applied to the post-thrombectomy patients exhibiting no extravasation of Gd-DTPA. Whole brain mapping of rWEI took less than 10 min and identified regions with subtle impairment of the blood-brain barrier.
    Figure 1. Representative MRI of thrombotic stroke patients who have undergone thrombectomy: despite the lack of Gd-DTPA extravasation, rWEI map identifies the areas with compromised BBB function.
    Figure 2. Ratios of values from ROI’s between ipsi- and contra-hemisphere. Both WEI and rWEI are stable in non-infarct areas across hemispheres while both are elevated in infarct regions. The difference between WEI and rWEI ratios in infarct regions may be due to a nonlinear relationship between CBV and rCBV.
  • Effect of low dose daily aspirin on cerebral blood flow and kidney function in hypertensive rats
    Greg O Cron1, Rafael Glikstein2, Jean Francois Thibodeau3, Anthony Carter3, Chet E Holterman3, Alexey Gutsol3, Lihua Zhu3, Baptiste Lacoste3, and Chris Kennedy3
    1Ottawa Hospital Research Institute, Ottawa, ON, Canada, 2The Ottawa Hospital, Ottawa, ON, Canada, 3University of Ottawa, Ottawa, ON, Canada
    We hypothesized that hypertension predisposes rats to low-dose aspirin induced kidney and cerebrovascular injury.  Results showed that these rats appeared to have decreased cerebral blood flow and significant kidney and cerebrovascular injury.
    Whole-brain cerebral blood flow in rats at +4 and +8 weeks post treatment, for the four groups studied.
    Urinary albumin levels, measured by ELISA, as a surrogate of kidney injury. Higher values suggest more kidney injury.
  • DTI-based Longitudinal Assessment of Stroke Recovery at 21.1 T
    David C. Hike1,2, Taylor A. Ariko1,2, Frederick A. Bagdasarian1,2, Shannon Helsper1,2, and Samuel Colles Grant1,2
    1National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, United States, 2Chemical & Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
    This research provides a method for monitoring the progression of stroke recovery and highlights the continuous degradation that occurs for multiple days after the stroke event, even after cerebral blood flow is re-established.
    Figure 1: Weighted degree in the parietal region of the brain over 30 days post ischemic event . No change is seen in the contralateral side 1 day post stroke; however, effects of edema can be seen on the ipsilateral side. Weighted degree levels can be seen returning to control levels at day 9 until spiking at day 30. Contralateral (right) changes at days 3 & 5 can be attributed to swelling on the ipsilateral (left) side that compresses the contralateral hemisphere.
    Figure 3: Changes in betweenness centrality in the piriform region indicate how many times a node acts as a bridge. Immediately following stroke, the ipsilateral side shows an increase in the number of nodes acting as a bridge while the contralateral side displays a slight delay. The contralateral also recovers sooner than the ipsilateral, indicating a prolonged/delayed restructuring process on that side.
  • Fast Tractography Demonstrates the Topography of the Corpus Callosum In Ideal and Post-stroke Conditions
    Jacqueline Chen1, Mark Lowe1, Ken Sakaie1, Kenneth Baker2, Andre Machado3, and Stephen Jones1
    1Cleveland Clinic Imaging Institute, Cleveland, OH, United States, 2Cleveland Clinic Lerner Research Institute, Cleveland, OH, United States, 3Cleveland Clinic Neurological Institute, Cleveland, OH, United States
    We developed a white-matter tractography method that uses local and global information to improve accuracy, and partial differential equation solvers for fast whole-brain mapping. Topological maps of the corpus callosum are generated to demonstrate accuracy and clinical relevance.
    Figure 2: (A) Anterior CC contained tracks from the most anterior and inferior regions of prefrontal cortex. (B) Mid-Anterior CC contained tracks from caudal anterior cingulate and superior & middle frontal cortical regions. (C) Central and Mid-Posterior CC contained tracks from cortical regions proximal to the central sulcus (precentral, paracentral, postcentral) and lateral sulcus (insula, transverse temporal, superior temporal, supramarginal). (D) Posterior CC contained tracks from posterior parietal, inferior temporal and occipital lobes.
    Figure 3: (A) Phantom mid-sagittal CC showing the ideal intersection of the transcallosal tracks (green) between precentral gyri. (B) The intersection of tracks (red) between precentral gyri for Patient A shows a region where no tracks were detected (yellow arrow) but were found in (A). (C) The intersection of tracks (blue) between precentral gyri for Patient B had a similar extent along the CC as the phantom.
  • Quantitative Analysis of DCE-MRI Following Transient Middle Cerebral Artery Occlusion in a Novel Ovine Model
    Alexandra Ereni King1, Paul D Teal2, Yu-Chieh Tzeng3, Annabel Jain Sorby-Adams4, Isabella Megan Bilecki4, Renée Jade Turner4, and Sergei Obruchkov5
    1School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand, 2School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand, 3Centre for Translational Physiology, University of Otago, Wellington, New Zealand, 4Discipline of Anatomy and Pathology, University of Adelaide, Adelaide, Australia, 5Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand
    Quantitative perfusion parameters (e.g. volume transfer coefficient, interstitial and plasma volume fractions) in a novel ovine model of stroke are calculated from DCE-MRI images of the healthy animal, at 24 hours, 3 days, 6 days and 28 days post stroke.

    Perfusion map of Ktrans [min-1] (top row) and vp [arb.] (second row), T1 weighted images (third row), and diffusion weighted images (bottom row) of a single animal from before stroke, 24 hours post stroke, and 6 days post stroke.

  • Evaluation of pharmacological hypothermia in rhesus monkey brains using diffusion MRI
    Xiaodong Zhang1, Chunxia Li1, Xiaohuan Gu2, Doty Kempf1, Ling Wei2, and Shan Ping Yu2
    1Yerkes Imaging Center, Emory University, Atlanta, GA, United States, 2Department of Anesthesiology, Emory University, Atlanta, GA, United States
    The monkey brain and body temperatures were reduced by administration of ABS-201. Gender difference of the drug-induced hypothermia was observed. The difference of temperature reduction between the monkey brain and body were seen .
    The progressive changes of the brain and body temperatures in adult monkeys administrated with saline or the novel neurotensin analog (ABS-201)
    The Temperature (°C) Changes in the Body and Brain of Each Monkey after administrated with saline or the novel neurotensin analog (ABS-201)
  • Predictive value of perfusion reduction on ASL for the occurrence of cerebrovascular events in patients with bilateral moyamoya angiography
    Maoxue Wang1, Yongbo Yang1, Fei Zhou1, Ming Li1, Jilei Zhang2, and Bing Zhang1,3
    1The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China, 2Philips Healthcare, Shanghai, China, 3Institute of Brain Science, Nanjing University Nanjing, Nanjing, China
    The mean value of CBF in cerebral hemispheres with lesions was lower than that on the contralateral side in ASL with PLDs of 1.5 s and 2.5 s, and it was correlated with the occurrence of cerebrovascular events.
    Figure 1. A 61-year-old patient with bilateral MMA. (A) Occlusion of bilateral ICA, ACA, and MCA was observed on 3D time of flight MRA images. (B) He had a punctate acute cerebral infarction in the left frontal lobe. The perfusion of the left frontal lobe decreased, and the arterial transit artifact was grade 2 on CBF images when PLD were 1.5 s and 2.5 s (C and D). (E and F) Three-dimensional images of bilateral cerebral hemispheres. The gray value of the left cerebral hemisphere was less than that of the contralateral on the gray distribution histogram of bilateral cerebral hemispheres.
    Table 2. Correlation between the degree of intracranial artery, cerebral perfusion, and occurrence of cerebrovascular events in patients with MMA.
  • Intravoxel incoherent motion two-in-one MR sequence for ischemic stroke diagnosis. Initial clinical experience at 3T.
    Aude Pavilla1,2, Giulio Gambarota1, Alessandro Arrigo2, Mehdi Mejdoubi2, and Hervé Saint-Jalmes1,3
    1Inserm, UMR 1099, Université de Rennes 1, LTSI, Rennes, France, 2Department of Neuroradiology, Pierre-Zobda-Quitman Hospital, University Hospital of Martinique, French West Indies, France, Fort-de-France, France, 3CRLCC, Centre Eugène Marquis, Rennes, France
    Student t-test revealed significant differences for all diffusion parameters with a significant decrease for D (p<0.0001), ADC (p<0.0001), and a significant  increase for K (p<0.0001) in the ischemic lesions . The perfusion parameter f decreased significantly in the ischemic regions.  

    DKI-IVIM analysis on one individual slice of diffusion-weighted images (b = 1000 s/mm ).

    (a) Signal intensity plotted as function of b-value for the two ROIs located in the ischemic lesion and normal contralateral region. The slope related to fD* between b = 0s/mm and b = 300 s/mm is decreased for the ischemic region.

    (b) Free-hand region of interest (ROI) delineation in the ischemic lesion and the corresponding contralateral ROI on normal tissues.

    Intravoxel incoherent motion (IVIM) parameters (D, f and fD*) and conventional apparent diffusion coefficient (ADC) and the cerebral blood flow (CBF) mesured through ASL in the lesion and the controlateral normal region averaged over all the stroke patients. Comparison with motion correction data processing for the DKI-IVIM analysis.

  • Altered cognition and emotion-related brain regions in asymptomatic carotid vulnerable plaque group: whole-brain voxel-wise analysis of IVIM
    Shuai Yang1, Jiuqing Guo1, Lirong Ouyang1, and Weiyin Vivian Liu2
    1Department of Radiology, Xiangya Hospital, Central South University, Changsha, China, 2MR Research, GE Healthcare, Beijing, China
    Our study was the first application of whole-brain voxel-wise comparisons of IVIM-derived normalized Ds and f values to show physiological alterations in cognition and emotion-related brain of patients with asymptomatic carotid vulnerable plaque.
    (a) Increased Ds values at left median cingulate and paracingulate gyrus (DCG.L), posterior cingulate gyrus (PCG.L) and left precuneus gyrus (PCUN.L) (cluster size = 156), left middle frontal gyrus (MFG.L), orbital middle frontal gyrus (ORBmid.L) and superior frontal gyrus (SFG.L) (cluster size = 165) (p <0.05, FWE correction). (b) Decreased Ds values at right middle temporal gyrus (MTG.R), inferior temporal gyrus (ITG.R)(cluster size = 116)(p <0.05, FWE correction). (c) Decreased f values at MTG.R,ITG.R(cluster size = 85) (p <0.05, FWE correction).
  • A Fast Tissue Segmentation Algorithm Using ASL Fingerprint Timeseries
    Luis Hernandez-Garcia1, Anish Lahiri2, Scott Peltier2, Jon Fredrik Nielsen2, and Benjamin Hampstead2
    1FMRI Laboratory, University of Michigan, Ann Arbor, MI, United States, 2University of Michigan, Ann Arbor, MI, United States
    The algorithm presented here can correctly identify tissue type fractions in brain tissue from ASL fingerprints.
    Canonical time courses resulting from clustering algorithm (left). The corresponding maps are shown on the right. These were calculated by linear regression of the canonical maps from the raw data.
    Fractional maps obtained from two subjects. Subject 2 showed significantly enlarged ventricles and grey matter atrophy.