Chunming Gu^1,2,3, Di Cao^1,2,3, Xinyuan Miao^2,3, Adrian G Paez^2,3, Jitong Cai¹, Yinghao Li^1,2,3, Wenbo Li^2,3, Jay J Pillai^4,5, Peter C.M. van Zijl^2,3, and Jun Hua^2,3
1Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States, ²Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ³F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, ⁴Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁵Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States

The iVASO MRI is a noninvasive approach for quantitative mapping of CBVa in the brain. It was originally developed in the single-slice mode. Recently, CBVa measured by single-slice iVASO has been validated using histological markers of arteriolar blood vessels in a mouse model. Here, we demonstrate an optimized 3D iVASO MRI protocol with a 3D turbo-field-echo (TFE) readout and a whole-brain coverage. It showed consistent CBVa measures when compared to the original single-slice iVASO. In 3D-TFE-iVASO, the imaging slab volume did not show significant effects on the measured CBVa values. CBVa measured with 3D-TFE-iVASO showed reasonable intra-subject reproducibility.

Benjamin Pryor Bonner^1,2,3, Jaume Coll-Font^1,2,4, Salva Yurista^1,2,4, Anna Foster^1,2, Robert Eder^1,2, Shi Chen^1,2, Peter Caravan^2,4, Eric Gale^2,4, and Christopher Nguyen^1,2,4,5
1Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, United States, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ³Louisiana State University Health Sciences Center, New Orleans, New Orleans, LA, United States, ⁴Harvard Medical School, Boston, MA, United States, ⁵Division of Health Science Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA, United States

Cardiac MRI a powerful imaging modality to assess cardiac anatomy and function, and its utility can be greatly enhanced with the use of contrast agents. Conventional contrast agents are nephrotoxic which limits their utility. We evaluate a novel contrast agent which is safe for use in renal dysfunction. We compare its performance against that of a conventional agent a porcine model of ischemia-reperfusion. This novel contrast agent demonstrates equivalent performance in assessing myocardial fibrotic scars, indicating its potential clinical use in the workout of cardiac patients with renal impairment.

Salah Assana¹, Manuel Morales¹, Kei Nakata¹, Eiryu Sai¹, Amine Amyar¹, Hassan Haji-Valizadeh¹, and Reza Nezafat^1
1Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Boston, MA, United States

Myocardial perfusion assessment using cardiac MRI allows non-invasive assessment of myocardial ischemia. In myocardial perfusion sequence, imaging is collected after a saturation pulse. An alternative approach based on steady-state imaging with radial sampling has been recently proposed. However, image reconstruction using compressed sensing in steady-state myocardial perfusion remains long and clinically not feasible. In this study, we sought to develop a deep learning-based image reconstruction platform for myocardial perfusion imaging.

William D Reeves¹, Ishfaque Ahmed¹, Wenwu Sun¹, Michelle Brown², Celestine Williams², Catherine L Davis², Jennifer E McDowell³, Nathan Yanasak⁴, Shaoyong Su², and Qun Zhao^1
1Department of Physics, University of Georgia, Athens, GA, United States, ²Georgia Prevention Institute, Augusta University, Augusta, GA, United States, ³Department of Psychology, University of Georgia, Athens, GA, United States, ⁴Department of Radiology and Imaging, Augusta University, Augusta, GA, United States

In a cross-sectional study of hypertension and its effects on brain connectivity, graph theory can be used to show cerebral blood flow connectivity differences between normotensive (n=32) and hypertensive (n=37) subjects. We obtain adjacency matrices from processed arterial spin labelling scans which can be used to determine several quantifications based on graph theory analysis. We find that normotensive subjects exhibit higher small-worldness and global efficiency (σ = 3.30 and E_glob = 0.73) compared to hypertensive subjects (σ = 1.82 and E_glob = 0.46). This trend continues for nearly all thresholding values and implies a measurable perfusion difference between the groups.

Donghoon Kim^1,2, Megan Lipford³, Hongjian He⁴, Qiuping Ding⁴, Vladimir Ivanovic², Samuel Lockhart⁵, Suzanne Craft⁵, Christopher T. Whitlow³, and Youngkyoo Jung^1,2,3
1Biomedical Engineering, University of California, Davis, CA, United States, ²Radiology, University of California, Davis, CA, United States, ³Radiology, Wake Forest University, Winston-Salem, NC, United States, ⁴Center for Brain Imaging Science and Technology, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Zhejiang, China, ⁵Internal Medicine, Wake Forest University, Winston-Salem, NC, United States

A CNN algorithm was proposed to estimate ATT and CBF simultaneously, using multi-TI ASL, acquiring ASL images at multiple PLDs. Hierarchical structure of CNN was used to reduce the estimation error of ATT and CBF. The proposed method successfully estimated ATT and CBF maps using reduced numbers of TIs or averages with a higher accuracy than a conventional non-linear model fitting. The successful estimation of ATT and CBF using our H-CNN may allow a total scan time reduction with a smaller number of TIs or averages and improvements of image quality when a part of acquisition is corrupted.

Lincoln Kartchner¹, Dengrong Jiang², Parimal Joshi¹, Cuimei Xu², Hanzhang Lu², and Peiying Liu^1
1Department of Diagnostic Radiology & Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, ²Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Cerebrovascular reactivity (CVR) is typically assessed with a carbon dioxide (CO₂) stimulus combined with BOLD fMRI. Recently, resting-state BOLD fMRI has been shown capable of generating CVR maps, providing a potential for broader CVR applications in neuroimaging studies. However, prior RS-CVR studies have primarily been performed at a spatial resolution of 3-4mm³ voxel sizes. It remains unknown whether RS-CVR can also be obtained at high-resolution without major degradation in image quality. In this study, we investigated the feasibility of high-resolution CVR mapping based on resting-state fMRI data. Our results showed good CVR quality can be obtained at 2-3mm³ voxel sizes.

Xiuyuan Wang¹, Siddhant Dogra², Koto Ishida³, Alejandro Gupta², Deqiang Qiu⁴, and Seena Dehkharghani^2,3
1Department of Radiology, Weill Cornell Medicine, New York, NY, United States, ²Department of Radiology, New York University Langone Health, New York, NY, United States, ³Department of Neurology, New York University Langone Health, New York, NY, United States, ⁴Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States

Cerebrovascular reactivity (CVR) is a widely used estimation of hemodynamic stress and ischemic stroke risk but its semi-quantitative nature relegates it primarily to estimations of relative change by comparison to putatively normal territories. Diagnostic and prognostic utility is thus attenuated in commonly encountered patients with bihemispheric disease, thus we have tested approaches for identification of candidate healthy voxels accompanying perfusion imaging or inline calibration of BOLD temporal shift, optimized in a cohort of subjects with strictly unilateral macrovascular disease. Excellent agreement with normative CVR values was observed, suggesting its applicability in patients with multi-focal or ambiguous vascular disease patterns.

Feng Xu^1,2, Cuimei Xu¹, Dapeng Liu^1,2, Dan Zhu², Hanzhang Lu^1,2, and Qin Qin^1,2
1The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States, ²F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States

Saturation based velocity-selective ASL (VSASL) was recently investigated for acetazolamide challenge and notably lower cerebrovascular reactivity (CVR) was observed when comparing to PET results. Here we compared the performance of velocity-selective inversion (VSI) prepared ASL and pseudo-continuous ASL in response to the hypercapnia challenge for CO2-induced CVR quantification with phase-contrast MRI as a global reference. VSI-ASL could underestimate the regional CVR when the trailing edge of the labeled bolus arrive before the PLD as the CBF during hypercapnia would be underestimated. In contrast, PCASL could overestimate CVR in areas with long ATT as the baseline CBF would be underestimated.

Zhehao Hu^1,2, Nan Wang³, Anthony Christodoulou^2,3, Mark Shiroishi¹, Gabriel Zada⁴, Debiao Li^2,3, and Zhaoyang Fan^1,5,6
1Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ²Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States, ³Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ⁴Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ⁵Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ⁶Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States

MR Multitasking-based Dynamic Imaging for Cerebrovascular Evaluation (MT-DICE) technique is recently developed and has the potential to provide DCE- and leakage-corrected DSC-MRI parameters simultaneously with one 7.6-minute scan and a single-dose contrast injection. However, it remains a practical challenge to validate the technique against their respective references with repeated contrast injections in separate days. In this work, we perform a numerical simulation study to validate the accuracy of MT-DICE in the estimation of permeability and leakage-corrected perfusion metrics.

Antonio Maria Chiarelli¹, Eleonora Piccirilli¹, Carlo Sestieri¹, Daniele Mascali¹, Emma Biondetti¹, Antonio Ferretti¹, Richard Wise¹, and Massimo Caulo^1,2
1Department of Neuroscience, Imaging and Clinical Sciences, University G. D'Annunzio of Chieti Pescara, Chieti, Italy, ²Department of Radiology, SS. Annunziata University Hospital, Chieti, Italy

During the perinatal period the brain undergoes extensive development, including increasing brain perfusion and metabolism. More rapidly modifying brain areas may be more sensitive to insults and transient hypoxic states. We performed PCASL on 115 infants at term equivalent age (TEA) with variable gestational age at birth. Insular-subcortical and somato-motor regions exhibited high grey matter CBF_(GM) in both term and preterm newborns. However, premature neonates showed a redistribution of perfusion compared to term infants, with somato-motor regions showing even higher CBF_GM. These results suggest that insular-subcortical and somato-motor regions may reflect brain health and development at TEA.

Tim Ottens¹, Sebastiano Barbieri², Matthew Orton³, Remy Klaassen⁴, Hanneke van Laarhoven⁴, Hans Crezee⁵, Aart Nederveen¹, and Oliver Gurney-Champion^1
1Radiology and Nuclear Medicine, Amsterdam UMC, Amsterdam, Netherlands, ²Centre for Big Data Research in Health, Sydney, Australia, ³Radiology, The Royal Marsden NHS Foundation Trust and The Institute for Cancer Research, London, United Kingdom, ⁴Medical Oncology, Amsterdam UMC, Amsterdam, Netherlands, ⁵Radiation Oncology, Amsterdam UMC, Amsterdam, Netherlands

Quantitative physiological perfusion parameters can be obtained from dynamic contrast-enhanced (DCE)-MRI. Conventionally, fitting is done with the non-linear least squares (NLLS) approach. However, the NLLS-fit suffers from long processing times and results in noisy parameter maps. In this work, we implemented a physics-informed gated recurrent unit (GRU) network with attention layers for estimating physiological parameters using the extended Tofts model. In simulations, we show it outperforms NLLS with more accurate and precise parameter maps. We show our method produced substantially less noisy parameter maps than NLLS in a fraction of the time in pancreatic cancer patients.

Andrew B. Gill¹ and Martin J. Graves^1
1Radiology, University of Cambridge, Cambridge, United Kingdom

Extending work by the QIBA initiative and others, a method is presented here for the generation of configurable digital reference objects (DROs) for the validation of dynamic-contrast enhanced (DCE-) MRI analysis software packages. Five commonly used kinetic models are supported and two software analysis packages were independently tested, one open source and one commercial. A sample set of DROs yielded excellent concordance with ‘ground-truth’ when analyzed with each package, indicating the software’s correctness and providing a benchmark for testing newly written software. Our MATLAB code is provided on an open-source basis to help researchers evaluate and test DCE-MRI analysis software.

Steven KS Cho¹, Jack RT Darby², Georgia K Williams³, Catherine G Dimasi², Stacey L Holman², Joseph B Selvanayagam⁴, Christopher K Macgowan⁵, Janna L Morrison², and Mike Seed^6
1Physiology, University of Toronto, North York, ON, Canada, ²Early Origins of Adult Health Research Group, Health and Biomedical Innovation, University of South Australia, Adelaide, Australia, ³South Australian Health & Medical Research Institute, Preclinical, Imaging & Research Laboratories, Adelaide, Australia, ⁴Cardiac Imaging Research Group, Department of Heart Health, South Australian Health and Medical Research Institute, Flinders University, Adelaide, Australia, ⁵Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ⁶Division of Cardiology, The Hospital for Sick Children, Toronto, ON, Canada

We investigated the accuracy of cardiac MRI for detecting myocardial infarction (MI) induced by coronary artery ligation surgery in a sheep model. 3D-inversion recovery (IR) FLASH sequence and first-pass perfusion imaging was feasible and provided accurate information about the size and location of MI immediately after surgery and at 15-day follow-up. The IR-FLASH sequence detected infarcts (91.2% sensitivity, 99.9% specificity) compared with gold-standard pathology staining findings. This may prove useful for preclinical research in which it is important to document the natural history of myocardial injury, such as in studies investigating interventions aimed at mitigating the long-term impact of MI.