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Guangqi Li¹, Yajing Zhang², and Hua Guo^1
1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, ²MR Clinical Science, Philips Health Technology (China), Beijing, China

Keywords: Multi-Contrast, Brain

Fast multi-contrast brain exams are highly desirable in clinical practice. Spiral sampling has high efficiency in terms of spatial encoding. Thus it holds great potential for many MRI applications. In this work, we optimized a fast multi-contrast brain imaging protocol based on multi-shot spiral acquisitions. Six contrasts (T1W-FLAIR, T2W, PDW, T2*W, T2W-FLAIR, DWI) and apparent diffusion coefficient (ADC) maps with an in-plane resolution of 1.0 mm² for a full brain MR exam can be obtained in about 2 minutes.

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Nils Marc Joel Plähn¹, Adèle Mackowiak², Berk Açikgöz³, Eva Peper³, Giulia Rossi², and Jessica Bastiaansen^3
1Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern Universit, Bern, Switzerland, ²Department of Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, ³Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland

Keywords: Relaxometry, Data Analysis, phase-cycled bSSFP, T1-quantification, T2-quantification, B0 quantification, proton-density quantification, multi-parameter quantification

A novel analytical method for off-resonance encoded parameter quantification of voxel-wise phase-cycled bSSFP signal profiles was developed. The approach conserves both magnitude and phase information in a complete, linearized, and compact way. A framework for ultra-rapid and simultaneous $$$T_1$$$, $$$T_2$$$, $$$B_0$$$ inhomogeneity and proton density quantification were developed. The approach was validated in simulations, phantom and in vivo knee experiments and compared with gold-standard reference measurements when available. Simulations and experiments validated the proposed method for multi-parameter quantification with high accuracy and precision, providing the first step towards novel analytical quantification possibilities with phase-cycled bSSFP.

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Jose Raul Velasquez Vides¹, Carl J. J. Herrmann^1,2, Ludger Starke^1,3, Hampus Olsson¹, and Thoralf Niendorf^1,4
1Berlin Ultrahigh Field Facility (B.U.F.F), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany, ²Department of Physics, Humboldt University of Berlin, Berlin, Germany, ³Digital Health - Machine Learning Research Group, Digital Health Center, Hasso Plattner Institute, University of Potsdam, Potsdam, Germany, ⁴Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany

Keywords: Relaxometry, Multiple Sclerosis

 One obstacle of established quantitative resonance imaging methods is the excessive scan time. This study examines the use of radially-sampled 2in1-RARE-EPI in conjunction with model-based reconstruction methods for accelerated and simultaneous PD, T_2, and $$$T_{2}^{*}$$$ mapping. We demonstrate that this approach facilitates a substantial decrease in acquisition time (01:40 vs. 07:12 min) of 2in1-RARE-EPI without impairing the quality of the parametric maps. Our patient data demonstrate the applicability of model-based reconstructed 2in1-RARE-EPI for T₂ and $$$T_{2}^{*}$$$ mapping of multiple sclerosis lesions.

 

 

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Shengwen Deng¹, Walter Zhao^2,3, David W. Jordan¹, Chaitra Badve ^1,4, and Dan Ma^2
1Department of Radiology, Case Western Reserve University and University Hospitals Cleveland Medical Center, Cleveland, OH, United States, ²Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, ³Case Western Reserve University School of Medicine, Cleveland, OH, United States, ⁴Seidman Cancer Center and Case Comprehensive Cancer Center,, Cleveland, OH, United States

Keywords: Relaxometry, MR Fingerprinting, Delta Relaxometry; Tumor Imaging

The influence of hemodynamics and contrast concentration can be eliminated with ratios between delta-relaxometry in contrast-enhanced MR Fingerprinting (MRF). This delta ratio can be used to characterize the in vivo contrast-specific tissue response, beyond the conventional T₁/T₂ shortening effect. In this abstract, we: 1) developed a MRF-based strategy to image the concentration-independent, contrast-specific tissue response using delta-relaxometry; 2) validated reproducibility and linearity of delta-relaxometry in phantom experiments; 3) reported the novel Delta-relaxometry image contrast distinct from current clinical image contrasts; and 4) illustrated the sensitivity of delta-relaxometry in brain tumor characterization and classification.

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Can Wu¹, Victor Murray¹, Syed Siddiq¹, Neelam Tyagi¹, Marsha Reyngold², Christopher Crane², and Ricardo Otazo^1,3
1Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, United States, ²Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, United States, ³Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States

Keywords: Multi-Contrast, Cancer

Real-time multi-contrast 4D MRI is proposed by transferring motion from 4D T1-weighted images to 3D T2-weighted images and performing fast signature matching based on T1-weighted 3D radial stack-of-stars acquisitions. The proposed approach exploits the anatomical correlations between T1-weighted and T2-weighted images and fast acquisition of T1-weighted data to generate real-time multi-contrast volumetric motion information for adaptation and monitoring of radiation treatment of tumors affected by respiratory motion on an MR-Linac system. The feasibility of the proposed method was demonstrated on patients with pancreatic cancer.

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Ben Dickie^1,2, Thomas Kisby³, Emily Rowling⁴, Julius Chung⁵, Mohammad Babur⁴, Lidan Christie¹, Tao Jin⁵, Kostas Kostarelos^3,6, Kaye Williams⁴, and James O'Connor^7
1Division of Informatics, Imaging and Data Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK, Manchester, United Kingdom, ²Geoffrey Jefferson Brain Research Centre, University of Manchester, Manchester Academic Health Science Centre, UK, Manchester, United Kingdom, ³Nanomedicine Lab, Faculty of Biology, Medicine and Health and National Graphene Institute, University of Manchester, UK, Manchester, United Kingdom, ⁴Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK, Manchester, United Kingdom, ⁵Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA, Pittsburgh, PA, United States, ⁶Catalan Institute of Nanoscience and Nanotechnology (ICN2), UAB Campus Bellaterra, Barcelona, Spain, Barcelona, Spain, ⁷Division of Cancer Sciences, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK, Manchester, United Kingdom

Keywords: Multi-Contrast, Cancer

We have developed a non-invasive imaging protocol for dual assessment of hypoxia and glucose uptake in tumours using oxygen-enhanced MRI and glucoCESL MRI, and test feasibility in GL261 glioblastoma and MOC2 head and neck cancer mouse models. GL261 tumours had a lower non-perfused fraction (p = 0.0015), a trend to higher glucose enhancing fraction (p = 0.07) and a smaller hypoxic glucose refractory fraction (p= 0.021). The normoxic glucose enhancing fraction was significantly larger than the normoxic glucose refractory fraction (p < 0.0001) in both models. These imaging tools will be used to assess the effects of hypoxia modifying drugs.

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Xingzheng Pan¹, Alyssa Lie², Renita Martis¹, Beau Pontre³, Julie Lim¹, Thomas White⁴, and Paul Donaldson^1
1Physiology, University of Auckland, Auckland, New Zealand, ²Optometry and Vision Science, University of Auckland, Auckland, New Zealand, ³Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand, ⁴Physiology and Biophysics, Stony Brook University, New York, NY, United States

Keywords: Relaxometry, Oxygenation, Human eye

The vitreous humour is a clear, gel-like fluid to provide structural support to the eye. Recently, it has been shown that the vitreous is important in regulating oxygen levels within the back of the eye. However, with ageing, the vitreous undergoes liquefaction, and as a result, oxygen is able to be move more freely throughout the vitreous, which increases the exposure of tissues such as the lens to oxygen. In this study, we developed MRI-based protocols to clinically monitor the oxygen levels and the fluid viscosity of the vitreous  and applied these protocol in a cohort of elderly partipants. 

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Choong Heon Lee¹, Mara Holloman², Jacob Brady³, James L. Salzer², and Jiangyang Zhang^1
1Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, ²Department of Neuroscience and Physiology, Neuroscience Institute, New York University School of Medicine, New York, NY, United States, ³UConn Health, Farmington, CT, United States

Keywords: Multi-Contrast, Microstructure

Although multiple MRI-based myelin marker have been introduced, their sensitivity and specificity remained limited. Multi-parametric MRI can potentially enhance myelin mapping, but validation remains challenging. In this study, we compared myelin histology from the Gli1^-/- mouse brain, which has enhanced myelination, with MRI markers based on relaxation, magnetization transfer, and diffusion properties from the same animals. We found varying degrees of correlation between MRI markers and myelin basic protein signals in multiple brain regions. Partial least square regression analysis demonstrated that multi-parametric MRI can indeed improve myelin mapping and provided information for further optimization.

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Simon Legeay¹, Mykyta Smirnov², Maëlig Chauvel¹, Bastien Herlin¹, Laurent Barantin^2,3, Ivy Uszynski¹, Igor Lima Maldonado^2,3, Christophe Destrieux^2,3, and Cyril Poupon^1
1BAOBAB, NeuroSpin, Université Paris-Saclay, CNRS, CEA, Gif-sur-Yvette, France, ²UMR 1253, iBrain, Université de Tours, Inserm, Tours, France, ³CHRU de Tours, Tours, France

Keywords: Relaxometry, Ex-Vivo Applications, Quantitative Imaging

The arterial distribution territories of the brain remain poorly characterized and are of major importance for treating ischemic strokes. We propose a new quantitative MRI approach for ex vivo mapping of vascular territories using paramagnetic gelatin injection into cerebral arteries to enhance MRI contrast at the gelatin level. This method was applied on one healthy human brain injected into the middle cerebral artery and accurately quantified the volume fraction of blood using a dedicated protocol and a modeling of the injected tissue signal. We projected the resulting mapping along the deep white matter fiber bundles.

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Cristina Sainz Martinez^1,2, José P. Marques³, Gabriele Bonanno^4,5,6, Tom Hilbert^4,7,8, Constantin Tuleasca^8,9,10, Meritxell Bach Cuadra^2,7, and João Jorge^1
1CSEM - Swiss Center for Electronics and Microtechnology, Bern, Switzerland, ²CIBM Center for Biomedical Imaging, Lausanne, Switzerland, ³Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, Netherlands, ⁴Advanced Clinical Imaging Technology, Siemens Healthineers International AG, Bern, Switzerland, ⁵Translational Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine (SITEM), Bern, Switzerland, ⁶Magnetic Resonance Methodology, Institute of Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Switzerland, ⁷Department of Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, ⁸Signal Processing Laboratory 5 (LTS-5), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, ⁹Department of Clinical Neurosciences, Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland, ¹⁰Faculty of Biology and Medicine, University of Lausanne (UNIL), Lausanne, Switzerland

Keywords: Multi-Contrast, High-Field MRI, Thalamus, Nuclei, 7 Tesla, QSM

The ability to non-invasively image the thalamus and its different nuclei would be highly valuable to neuroscience and neuroradiology, but has remained challenging. Here, we initiated a comprehensive practical review of recent thalamic imaging approaches at 7 Tesla, based on T₁, T₂, T₂* and susceptibility properties. These were all acquired on the same in-vivo brain, to avoid anatomical variability confounds. The images were qualitatively compared to histological atlases. Upon systematic assessment, QSM and GM/WM-optimized MP2RAGE proved the most valuable to differentiate specific nuclei. To our knowledge, this is the most comprehensive evaluation to date of thalamic imaging modalities at 7T.

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Niklas Wallstein¹, André Pampel¹, Carsten Jäger¹, Roland Müller¹, and Harald E Möller^1,2
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, ²Department of Physics, Leipzig University, Leipzig, Germany

Keywords: Relaxometry, White Matter, T1 Anisotropy WM

In general, a broad consensus exists that dipolar couplings between water protons and motional restricted macromolecules are prominent modulators of longitudinal relaxation in WM. Recent studies demonstrate anisotropic relaxation in human white matter (WM) in dependence of the fibre-to-field orientation. Our approach for further investigations of such effects overcomes previous limitations, in particular, sample reorientations for a direct demonstration of orientation effects, which were missing in earlier studies. Samples of ex-vivo WM tissue of pig brain yielded slightly reduced spin-lattice relaxation times by 1-2% around an angle of 40° between the main fibre direction and B0.

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Tonima Ali^1,2, Jinglei Lv^1,2, Marshall Dalton^2,3, Steve Kassem⁴, Arkiev D'Souza^2,5, and Fernando Calamante^1,2,6
1School of Biomedical Engineering, The University of Sydney, Sydney, Australia, ²Brain and Mind Centre, The University of Sydney, Sydney, Australia, ³School of Psychology, The University of Sydney, Sydney, Australia, ⁴Neuroscience Research Australia, Sydney, Australia, ⁵Translational Research Collective, The University of Sydney, Sydney, Australia, ⁶Sydney Imaging, The University of Sydney, Sydney, Australia

Keywords: Multi-Contrast, Diffusion/other diffusion imaging techniques, Brain, Gray matter, Segmentation, Neuro

We integrated the information from structural and diffusion MRI from a group of healthy subjects, to develop a data-driven parcellation of the human subcortex. We first identified the data features that are sensitive to the micro-architectural variabilities within subcortex and then segregated specialised sub-regions with discernible properties. Our parcellated sub-regions demonstrated remarkable similarities to known nuclei and sub-structures within striatum, globus pallidus, and thalamus. Our parcellation has also identified regions which are known to have distinct anatomical and functional properties but that are yet to be explicitly added to extant human brain atlases.

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Paul S Jacobs¹, Neil Wilson¹, Ravi Prakash Reddy Nanga¹, Blake Benyard¹, Kosha Ruparel², Dushyant Kumar¹, Mark A Elliott¹, David Roalf², and Ravinder Reddy^1
1Center for Advanced Metabolic Imaging in Precision Medicine, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²Department of Psychiatry, University of Pennsylvania, Philadelphia, PA, United States

Keywords: Contrast Mechanisms, White Matter, High-Field MRI, Inversion Recovery

Two sets of images were acquired on four healthy subjects using separate on-resonance selective and broadband inversion recovery (IR) sequences at nine different inversion times. These images were fit to a bi-exponential T₁ fitting model aiming to separate out specific long and short components. The selective IR data showed a substantial increase in white matter contrast compared to the broadband data with an average T₁ of approximately 300ms. This agrees with reported literature values of the T₁ of myelin and suggest it may be a potential driver of this selective short T₁ component contrast.

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Seong Dae Yun¹ and N. Jon Shah^1,2,3,4
1Institute of Neuroscience and Medicine 4, INM-4, Forschungszentrum Juelich, Juelich, Germany, ²Institute of Neuroscience and Medicine 11, INM-11, JARA, Forschungszentrum Juelich, Juelich, Germany, ³JARA - BRAIN - Translational Medicine, Aachen, Germany, ⁴Department of Neurology, RWTH Aachen University, Aachen, Germany

Keywords: Contrast Mechanisms, Quantitative Imaging, 7T, Inversion-recovery EPI, Rapid T1 mapping, Submillimetre and Whole-brain

Knowledge of T₁ relaxation time is of great interest for clinical diagnosis or MRI sequence optimisation. For the quantitative measurement of T₁, the inversion-recovery method is widely used due to its relatively good accuracy or tolerance to B₁ inhomogeneity. However, 2D multi-slice- or 3D segmentation-based readout methods often preclude the effect of different signal recovery modulation depending on slice locations. Therefore, this work presents a single-slice-based inversion-recovery 2D EPI method, combined with TR-external EPI phase correction at 7T, to provide rapid, whole-brain T₁ mapping with a voxel size of 0.73 × 0.73 mm². 

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Matteo Cencini¹, Rolf F Schulte², Marta Lancione¹, Carolin M Pirkl², Laura Biagi¹, Graziella Donatelli^3,4, and Michela Tosetti^1
1IRCCS Stella Maris, Pisa, Italy, ²GE Healthcare, Munich, Germany, ³IMAGO7 Foundation, Pisa, Italy, ⁴Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy

Keywords: High-Field MRI, High-Field MRI

Fast quantitative MR methods enable repeatable and reproducible assessment of tissue properties improving diagnosis and follow-up. Here, we implemented two different 3D relaxometry methods based on quantitative transient-state imaging (QTI) for fast T1 and T2 mapping of the human brain at 7T. The two techniques were demonstrated both in-vitro and in-vivo and provided good quality parametric maps with low geometric distortion and blurring in clinically feasible acquisition and reconstruction times.

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Lucas Soustelle^1,2, Andreea Hertanu^1,2, Thomas Troalen³, Maxime Guye^1,2, Jean-Philippe Ranjeva^1,2, Guillaume Duhamel^1,2, and Olivier M. Girard^1,2
1Aix-Marseille Univ, CNRS, CRMBM, Marseille, France, ²APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France, ³Siemens Healthcare SAS, Marseille, France

Keywords: Relaxometry, Modelling, Microstructure, Nervous System

Common T₁ mapping methods are dependent on the biophysical model assumptions. Previous work based on a qMT-SPGR framework demonstrated the influence of magnetization transfer effects and the importance of appropriate sequence design and signal modelling for T₁ estimation. In this work, we expanded upon this optimized framework using an MP2RAGE sequence and demonstrated that quantitative T₁ values in agreement with VFA-based experiments can be obtained in the human brain.

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Joong Hee Kim¹, Govind Nair¹, Daniel Reich¹, and David L. Brody^1
1National Institute of Health, Bethesda, MD, United States

Keywords: Relaxometry, Low-Field MRI, Ultra low field

MR parameter mapping provides objective biomarkers for living tissues. However, long scan times and high field MR imaging are typically required, whereas few ultralow field MR scanner studies have been performed. Here we propose a simplified R1 mapping protocol with only two inversion delay time points (R1_approx), taking advantage of the fast R1 at ultralow field. The R1 characteristics of human brain were largely preserved in R1approx compared to standard inversion recovery R1 mapping. R1_approx. required under 30 minutes vs. ~two hours for standard R1 mapping. In addition, R1_approx. shows high reproducibility and good sensitivity to an R1 contrast agent.  

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Siyu Yuan¹, Hui Huang¹, Miao Zhang², Wei Liu³, Jiwei Li¹, Bingyang Cai¹, Ya Cui¹, and Jie Luo^1
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China, ²Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, ³Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Keywords: fMRI, PET/MR

It has been unclear whether metabolic-functional coupling could be disturbed in epileptogenic lesion and network by epileptic activities. In this study, we investigated metabolic changes, functional alterations and their couplings in epileptogenic lesion and network of mesial temporal lobe epilepsy (MTLE) using simultaneous PET/MR, and further evaluated the relationship between altered couplings and surgical outcome. MTLE patients showed abnormalities of standardized uptake value ratio (SUVR) and fractional amplitude of low-frequency fluctuation (fALFF) in default mode network (DMN). MTLE patients with hippocampal sclerosis (MR-HS) had higher SUVR-fALFF coupling in ipsilateral hippocampus and DMN, and the couplings were associated with surgical outcomes.

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Seong-min Kim¹, Kyeongseon Min², Jung Seung Lee^1,3, and Jang-Yeon Park^1,3
1Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ²Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of

Keywords: Contrast Mechanisms, Challenges, cell scan, qMR, ADC, T2, PSR

Our group recently reported a method for direct imaging of neuronal activity (DIANA), suggesting that its contrast mechanism is T₂ changes due to changes in membrane potential during neuronal activation, which accompanies cell swelling and changes in hydrating water modlecules of the cell membrane. In this study, by measuring apparent-diffusion-coefficient (ADC) and pool-size-ratio (PSR) versus T₂, respectively, we verified the respective contribution of cell swelling and changes in hydrating water modlecules to T₂ changes when only osmotic pressure or membrane potential was altered in T-lymphocyte cells in vitro. 

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Chiara Coletti¹, Maša Bozic-Iven^1,2, Joao Tourais¹, Christal van de Steeg-Henzen³, Mehmet Akcakaya⁴, and Sebastian Weingärtner^1
1TU Delft, Delft, Netherlands, ²Heidelberg University, Heidelberg, Germany, ³HollandPTC, Delft, Netherlands, ⁴University of Minnesota, Minneapolis, MN, United States

Keywords: Relaxometry, New Signal Preparation Schemes, T1ρ, Dark-blood, adiabatic

T_1ρ-mapping is emerging as a promising, contrast-free alternative to LGE for assessment of myocardial viability. However, high blood T_1ρ values can obfuscate endocardial scar. In this work, we propose a dark-blood adiabatic T_1ρ preparation to suppress the blood signal and improve depiction of the blood-myocardium interface. A slice-selection gradient is added to an odd number of adiabatic full passage pulses to achieve blood inversion outside the imaging slab. Phantom results show that DBT_1ρ yields unbiased estimation of T_1ρ time. In vivo, thorough blood suppression is achieved for the trade-off against a moderate increase in DBT_1ρ variance.