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Tao Q, Yi P, Cai Z, Chen Z, Deng Z, Liu R, Feng Y. Ratiometric chemical exchange saturation transfer pH mapping using two iodinated agents with nonequivalent amide protons and a single low saturation power. Quant Imaging Med Surg 2022; 12:3889-3902. [PMID: 35782235 PMCID: PMC9246745 DOI: 10.21037/qims-21-1229] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/29/2022] [Indexed: 07/26/2023]
Abstract
BACKGROUND As an essential physiological parameter, pH plays a critical role in maintaining cellular and tissue homeostasis. The ratiometric chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) method using clinically approved iodinated agents has emerged as one of the most promising noninvasive techniques for pH assessment. METHODS In this study, we investigated the ability to use the combination of two different nonequivalent amide protons, chosen from five iodinated agents, namely iodixanol, iohexol, iobitridol, iopamidol, and iopromide, for pH measurement. The ratio of two nonequivalent amide CEST signals was calculated and compared for pH measurements in the range of 5.6 to 7.6. To quantify the CEST signals at 4.3 and 5.5 parts per million (ppm), we employed two analytic methods: magnetization transfer ratio asymmetry and Lorentzian fitting analysis. Lastly, the established protocol was used to measure the pH values in healthy rat kidneys (n=5). RESULTS The combination of iodixanol and iobitridol at a ratio of 1:1 was found to be suitable for pH mapping. The saturation power level (B1) was also investigated, and a low B1 of 1.5 µT was adopted for subsequent pH measurements. Improved precision and an extended pH detection range were achieved using iodixanol and iobitridol (1:1 ratio) and a single low B1 of 1.5 µT in vitro. In vivo renal pH values were measured as 7.23±0.09, 6.55±0.15, and 6.29±0.23 for the cortex, medulla, and calyx, respectively. CONCLUSIONS These results show that the ratiometric CEST method using two iodinated agents with nonequivalent amide protons could be used for in vivo pH mapping of the kidney under a single low B1 saturation power.
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Affiliation(s)
- Quan Tao
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China
- Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education & Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Peiwei Yi
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China
- Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education & Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Zimeng Cai
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China
- Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education & Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Zelong Chen
- Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zongwu Deng
- CAS Key Laboratory of Nano-Bio Interface and Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, China
| | - Ruiyuan Liu
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China
- Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education & Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Yanqiu Feng
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, China
- Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education & Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
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Kombala CJ, Kotrotsou A, Schuler FW, de la Cerda J, Ma JC, Zhang S, Pagel MD. Development of a Nanoscale Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Contrast Agent That Measures pH. ACS NANO 2021; 15:20678-20688. [PMID: 34870957 DOI: 10.1021/acsnano.1c10107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
AcidoCEST MRI can measure the extracellular pH (pHe) of the tumor microenvironment in mouse models of human cancers and in patients who have cancer. However, chemical exchange saturation transfer (CEST) is an insensitive magnetic resonance imaging (MRI) contrast mechanism, requiring a high concentration of small-molecule agent to be delivered to the tumor. Herein, we developed a nanoscale CEST agent that can measure pH using acidoCEST MRI, which may decrease the requirement for high delivery concentrations of agent. We also developed a monomer agent for comparison to the polymer. After optimizing CEST experimental conditions, we determined that the polymer agent could be used during acidoCEST MRI studies at 125-fold and 488-fold lower concentration than the monomer agent and iopamidol, respectively. We also determined that both agents can measure pH with negligible dependence on temperature. However, pH measurements with both agents were dependent on concentration, which may be due to concentration-dependent changes in hydrogen bonding and/or steric hindrance. We performed in vivo acidoCEST MRI studies using the three agents to study a xenograft MDA-MB-231 model of mammary carcinoma. The tumor pHe measurements were 6.33 ± 0.12, 6.70 ± 0.15, and 6.85 ± 0.15 units with iopamidol, the monomer agent, and polymer agent, respectively. The higher pHe measurements with the monomer and polymer agents were attributed to the concentration dependence of these agents. This study demonstrated that nanoscale agents have merit for CEST MRI studies, but consideration should be given to the dependence of CEST contrast on the concentration of these agents.
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Affiliation(s)
- Chathuri J Kombala
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Aikaterini Kotrotsou
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - F William Schuler
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Jorge de la Cerda
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Jacqueline C Ma
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Shu Zhang
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Mark D Pagel
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
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Kombala CJ, Lokugama SD, Kotrotsou A, Li T, Pollard AC, Pagel MD. Simultaneous Evaluations of pH and Enzyme Activity with a CEST MRI Contrast Agent. ACS Sens 2021; 6:4535-4544. [PMID: 34856102 DOI: 10.1021/acssensors.1c02408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The extracellular tumor microenvironment of many solid tumors has high acidosis and high protease activity. Simultaneously assessing both characteristics may improve diagnostic evaluations of aggressive tumors and the effects of anticancer treatments. Noninvasive imaging methods have previously been developed that measure extracellular pH or can detect enzyme activity using chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI). Herein, we developed a single-hybrid CEST agent that can simultaneously measure pH and evaluate protease activity using a combination of dual-power acidoCEST MRI and catalyCEST MRI. Our agent showed CEST signals at 9.2 ppm from a salicylic acid moiety and at 5.0 ppm from an aryl amide. The CEST signal at 9.2 ppm could be measured after selective saturation was applied at 1 and 4 μT, and these measurements could be used with a ratiometric analysis to determine pH. The CEST signal at 5.0 ppm from the aryl amide disappeared after the agent was treated with cathepsin B, while the CEST signal at 9.2 ppm remained, indicating that the agent could detect protease activity through the amide bond cleavage. Michaelis-Menten kinetics studies with catalyCEST MRI demonstrated that the binding affinity (as shown with the Michaelis constant KM), the catalytic turnover rate (kcat), and catalytic efficiency (kcat/KM) were each higher for cathepsin B at lower pH. The kcat rates measured with catalyCEST MRI were lower than the comparable rates measured with liquid chromatography-mass spectrometry (LC-MS), which reflected a limitation of inherently noisy and relatively insensitive CEST MRI analyses. Although this level of precision limited catalyCEST MRI to semiquantitative evaluations, these semiquantitative assessments of high and low protease activity still had value by demonstrating that high acidosis and high protease activity can be used as synergistic, multiparametric biomarkers.
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Affiliation(s)
- Chathuri J. Kombala
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Sanjaya D. Lokugama
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Aikaterini Kotrotsou
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Tianzhe Li
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Alyssa C. Pollard
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
- Department of Chemistry, Rice University, Houston, Texas 77251, United States
| | - Mark D. Pagel
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
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Prasad S, Chandra A, Cavo M, Parasido E, Fricke S, Lee Y, D'Amone E, Gigli G, Albanese C, Rodriguez O, Del Mercato LL. Optical and magnetic resonance imaging approaches for investigating the tumour microenvironment: state-of-the-art review and future trends. NANOTECHNOLOGY 2021; 32:062001. [PMID: 33065554 DOI: 10.1088/1361-6528/abc208] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The tumour microenvironment (TME) strongly influences tumorigenesis and metastasis. Two of the most characterized properties of the TME are acidosis and hypoxia, both of which are considered hallmarks of tumours as well as critical factors in response to anticancer treatments. Currently, various imaging approaches exist to measure acidosis and hypoxia in the TME, including magnetic resonance imaging (MRI), positron emission tomography and optical imaging. In this review, we will focus on the latest fluorescent-based methods for optical sensing of cell metabolism and MRI as diagnostic imaging tools applied both in vitro and in vivo. The primary emphasis will be on describing the current and future uses of systems that can measure intra- and extra-cellular pH and oxygen changes at high spatial and temporal resolution. In addition, the suitability of these approaches for mapping tumour heterogeneity, and assessing response or failure to therapeutics will also be covered.
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Affiliation(s)
- Saumya Prasad
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
| | - Anil Chandra
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
| | - Marta Cavo
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
| | - Erika Parasido
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
- Center for Translational Imaging, Georgetown University Medical Center, Washington, DC, United States of America
| | - Stanley Fricke
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
- Center for Translational Imaging, Georgetown University Medical Center, Washington, DC, United States of America
- Department of Radiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Yichien Lee
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Eliana D'Amone
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
| | - Giuseppe Gigli
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
- Department of Mathematics and Physics 'Ennio De Giorgi', University of Salento, via Arnesano, 73100, Lecce, Italy
| | - Chris Albanese
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
- Center for Translational Imaging, Georgetown University Medical Center, Washington, DC, United States of America
- Department of Radiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Olga Rodriguez
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
- Center for Translational Imaging, Georgetown University Medical Center, Washington, DC, United States of America
| | - Loretta L Del Mercato
- Institute of Nanotechnology, National Research Council (CNR-NANOTEC), c/o Campus Ecotekne, via Monteroni, 73100, Lecce, Italy
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Abstract
OBJECTIVES The goal of this study was to demonstrate feasibility of measuring extracellular pH in cartilage and meniscus using acidoCEST technique with a 3-dimensional ultrashort echo time readout (acidoCEST-UTE) magnetic resonance imaging (MRI). MATERIALS AND METHODS Magnetization transfer ratio asymmetry, radiofrequency (RF) power mismatch, and relative saturation transfer were evaluated in liquid phantoms for iopromide, iopamidol, and iohexol over a pH range of 6.2 to 7.8, at various agent concentrations, temperatures, and buffer concentrations. Tissue phantoms containing cartilage and meniscus were evaluated with the same considerations for iopamidol and iohexol. Phantoms were imaged with the acidoCEST-UTE MRI sequence at 3 T. Correlation coefficients and coefficients of variations were calculated. Paired Wilcoxon rank-sum tests were used to evaluate for statistically significant differences. RESULTS The RF power mismatch and relative saturation transfer analyses of liquid phantoms showed iopamidol and iohexol to be the most promising agents for this study. Both these agents appeared to be concentration independent and feasible for use with or without buffer and at physiologic temperature over a pH range of 6.2 to 7.8. Ultimately, RF power mismatch fitting of iohexol showed the strongest correlation coefficients between cartilage, meniscus, and fluid. In addition, ratiometric values for iohexol are similar among liquid as well as different tissue types. CONCLUSIONS Measuring extracellular pH in cartilage and meniscus using acidoCEST-UTE MRI is feasible.
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Goldenberg JM, Pagel MD. Assessments of tumor metabolism with CEST MRI. NMR IN BIOMEDICINE 2019; 32:e3943. [PMID: 29938857 PMCID: PMC7377947 DOI: 10.1002/nbm.3943] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/13/2018] [Accepted: 04/18/2018] [Indexed: 05/06/2023]
Abstract
Chemical exchange saturation transfer (CEST) is a relatively new contrast mechanism for MRI. CEST MRI exploits a specific MR frequency (chemical shift) of a molecule while generating an image with good spatial resolution using standard MRI techniques, combining the specificity of MRS with the spatial resolution of MRI. Many CEST MRI acquisition methods have been developed to improve analyses of tumor metabolism. GluCEST, CrCEST, and LATEST can map glutamate, creatine, and lactate, which are important metabolites involved in tumor metabolism. GlucoCEST MRI tracks the pharmacokinetics of glucose transport and cell internalization within tumors. CatalyCEST MRI detects enzyme catalysis that changes a substrate CEST agent. AcidoCEST MRI measures extracellular pH of the tumor microenvironment by exploiting a ratio of two pH-dependent CEST signals. This review describes each technique, the technical issues involved with CEST MRI and each specific technique, and the merits and challenges associated with applying each CEST MRI technique to study tumor metabolism.
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Affiliation(s)
- Joshua M. Goldenberg
- Department of Pharmaceutical Sciences, The University of Arizona, Tucson, AZ, USA
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mark D. Pagel
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Dou W, Lin CYE, Ding H, Shen Y, Dou C, Qian L, Wen B, Wu B. Chemical exchange saturation transfer magnetic resonance imaging and its main and potential applications in pre-clinical and clinical studies. Quant Imaging Med Surg 2019; 9:1747-1766. [PMID: 31728316 PMCID: PMC6828581 DOI: 10.21037/qims.2019.10.03] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/29/2019] [Indexed: 12/26/2022]
Abstract
Chemical exchange saturation transfer (CEST) imaging is a novel contrast mechanism, relying on the exchange between mobile protons in amide (-NH), amine (-NH2) and hydroxyl (-OH) groups and bulk water. Due to the targeted protons present in endogenous molecules or exogenous compounds applied externally, CEST imaging can respectively, generate endogenous or exogenous contrast. Nowadays, CEST imaging for endogenous contrast has been explored in pre-clinical and clinical studies. Amide CEST, also called amide proton transfer weighted (APT) imaging, generates CEST effect at 3.5 ppm away from the water signal and has been widely investigated. Given the sensitivity to amide proton concentration and pH level, APT imaging has shown robust performance in the assessment of ischemia, brain tumors, breast and prostate cancer as well as neurodegenerative diseases. With advanced methods proposed, pure APT and Nuclear Overhauser Effect (NOE) mediated CEST effects were separately fitted from original APT signal. Using both effects, early but promising results were obtained for glioma patients in the evaluation of tumor response to therapy and patient survival. Compared to amide CEST, amine CEST is also mobile proton concentration and pH dependent, but has a faster exchange rate between amine protons and water. The resultant CEST effect is usually introduced at 1.8-3 ppm. Glutamate and creatine, as two main metabolites with amine groups for CEST imaging, have been applied to quantitatively assess diseases in the central nervous system and muscle system, respectively. Glycosaminoglycan (Gag) as a representative metabolite with hydroxyl groups has also been measured to evaluate the cartilage of knee or intervertebral discs in CEST MRI. Due to limited frequency difference between hydroxyl protons and water, 7T for better spectral separation is preferred over 3T for GagCEST measurement. The applications of CEST MRI with exogenous contrast agents are still quite limited in clinic. While certain diamagnetic CEST agents, such as dynamic-glucose, have been tried in human for brain tumor or neck cancer assessment, most exogenous agents, i.e., paramagnetic CEST agents, are still tested in the pre-clinical stage, mainly due to potential toxicity. Engineered tissues for tissue regeneration and drug delivery have also shown a great potential in CEST imaging, as many of them, such as hydrogel and polyamide materials, contain mobile protons or can be incorporated with CEST specific chemical compounds. These engineered tissues can thus generate CEST effect in vivo, allowing a possibility to understand the fate of them in vivo longitudinally. Although the CEST MRI with engineered tissues has only been established in early stage, the obtained first evidence is crucial for further optimizing these biomaterials and finally accomplishing the translation into clinical use.
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Affiliation(s)
- Weiqiang Dou
- MR Research, GE Healthcare, Beijing 100076, China
| | | | - Hongyuan Ding
- Department of Radiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yong Shen
- MR Enhanced Application, GE Healthcare, Beijing 100076, China
| | - Carol Dou
- Faculty of Medicine, University of British Columbia, British Columbia, Canada
| | - Long Qian
- MR Research, GE Healthcare, Beijing 100076, China
| | - Baohong Wen
- Department of MRI, First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Bing Wu
- MR Research, GE Healthcare, Beijing 100076, China
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Pinto SM, Tomé V, Calvete MJ, Castro MMC, Tóth É, Geraldes CF. Metal-based redox-responsive MRI contrast agents. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.03.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
This article aimed at reviewing the advances on the development of paramagnetic complexes used as chemical exchange saturation transfer agents in magnetic resonance imaging. This relatively new type of contrast opens new avenues in the development of MRI probes for molecular imaging, and coordination chemistry lies at the center of such advances. Strategies to detect important biomarkers such as pH, cations, anions, metabolites, enzyme, and O2 were described. The current challenges, limitations, and opportunities in this field of research were discussed.
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Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [ 18F]FDG PET and acidoCEST MRI. Mol Imaging Biol 2019; 20:575-583. [PMID: 29374343 DOI: 10.1007/s11307-018-1164-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE We sought to determine if the synergy between evaluations of glucose uptake in tumors and extracellular tumor acidosis measured with simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) can improve longitudinal evaluations of the response to metformin treatment. PROCEDURES A standard 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) PET protocol that evaluates glucose uptake in tumors, and a standard acidoCEST MRI protocol that measures extracellular pH (pHe) in tumors, were simultaneously performed to assess eight vehicle-treated (control) mice and eight metformin-treated mice 1 day before treatment, 1 day after initiating daily treatment with metformin, and 7 days after initiating treatment. Longitudinal changes in SUVmax and extracellular pH (pHe) were evaluated for each treatment group, and differences in SUVmax and pHe between metformin-treated and control groups were also evaluated. RESULTS MRI acquisition protocols had little effect on the PET count rate, and the PET instrumentation had little effect on image contrast during acidoCEST MRI, verifying that [18F]FDG PET and acidoCEST MRI can be performed simultaneously. The average SUVmax of the tumor model had a significant decrease after 7 days of treatment with metformin, as expected. The average tumor pHe decreased after 7 days of metformin treatment, which reflected the inhibition of the consumption of cytosolic lactic acid caused by metformin. However, the average SUVmax of the tumor model was not significantly different between the metformin-treated and control groups after 7 days of treatment, and average pHe was also not significantly different between these groups. For comparison, the combination of average SUVmax and pHe measurements significantly differed between the treatment group and control group on Day 7. CONCLUSIONS [18F]FDG PET and acidoCEST MRI studies can be performed simultaneously. The synergistic combination of assessing glucose uptake and tumor acidosis can improve differentiation of a drug-treated group from a control group during drug treatment of a tumor model.
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Wahsner J, Gale EM, Rodríguez-Rodríguez A, Caravan P. Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers. Chem Rev 2019; 119:957-1057. [PMID: 30350585 PMCID: PMC6516866 DOI: 10.1021/acs.chemrev.8b00363] [Citation(s) in RCA: 823] [Impact Index Per Article: 164.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compounds, and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathological changes in the local environment. This comprehensive review describes the state of the art of clinically approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chemical exchange saturation transfer, and direct detection and the types of molecules that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathology either by direct biochemical targeting or by the design of responsive or activatable contrast agents.
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Affiliation(s)
- Jessica Wahsner
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Eric M. Gale
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Aurora Rodríguez-Rodríguez
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Peter Caravan
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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Thorarinsdottir AE, Harris TD. Dramatic enhancement in pH sensitivity and signal intensity through ligand modification of a dicobalt PARACEST probe. Chem Commun (Camb) 2019; 55:794-797. [DOI: 10.1039/c8cc09520e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A ratiometric dicobalt PARACEST pH probe that exhibits dramatic enhancements in sensitivity and signal intensity over analogous probes is reported.
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Towards Ni(II) complexes with spin switches for 19F MR-based pH sensing. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2018; 32:89-96. [DOI: 10.1007/s10334-018-0698-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/23/2018] [Accepted: 08/02/2018] [Indexed: 01/09/2023]
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Thorarinsdottir AE, Tatro SM, Harris TD. Electronic Effects of Ligand Substitution in a Family of CoII2 PARACEST pH Probes. Inorg Chem 2018; 57:11252-11263. [DOI: 10.1021/acs.inorgchem.8b01896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
| | - Scott M. Tatro
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - T. David Harris
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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Okoh OA, Klahn P. Trimethyl Lock: A Multifunctional Molecular Tool for Drug Delivery, Cellular Imaging, and Stimuli-Responsive Materials. Chembiochem 2018; 19:1668-1694. [PMID: 29888433 DOI: 10.1002/cbic.201800269] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Indexed: 12/13/2022]
Abstract
Trimethyl lock (TML) systems are based on ortho-hydroxydihydrocinnamic acid derivatives displaying increased lactonization reactivity owing to unfavorable steric interactions of three pendant methyl groups, and this leads to the formation of hydrocoumarins. Protection of the phenolic hydroxy function or masking of the reactivity as benzoquinone derivatives prevents lactonization and provides a trigger for controlled release of molecules attached to the carboxylic acid function through amides, esters, or thioesters. Their easy synthesis and possible chemical adaption to several different triggers make TML a highly versatile module for the development of drug-delivery systems, prodrug approaches, cell-imaging tools, molecular tools for supramolecular chemistry, as well as smart stimuliresponsive materials.
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Affiliation(s)
- Okoh Adeyi Okoh
- Institute for Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
| | - Philipp Klahn
- Institute for Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
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16
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Jones KM, Randtke EA, Yoshimaru ES, Howison CM, Chalasani P, Klein RR, Chambers SK, Kuo PH, Pagel MD. Clinical Translation of Tumor Acidosis Measurements with AcidoCEST MRI. Mol Imaging Biol 2018; 19:617-625. [PMID: 27896628 DOI: 10.1007/s11307-016-1029-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE We optimized acido-chemical exchange saturation transfer (acidoCEST) magnetic resonance imaging (MRI), a method that measures extracellular pH (pHe), and translated this method to the radiology clinic to evaluate tumor acidosis. PROCEDURES A CEST-FISP MRI protocol was used to image a flank SKOV3 tumor model. Bloch fitting modified to include the direct estimation of pH was developed to generate parametric maps of tumor pHe in the SKOV3 tumor model, a patient with high-grade invasive ductal carcinoma, and a patient with metastatic ovarian cancer. The acidoCEST MRI results of the patient with metastatic ovarian cancer were compared with DCE MRI and histopathology. RESULTS The pHe maps of a flank model showed pHe measurements between 6.4 and 7.4, which matched with the expected tumor pHe range from past acidoCEST MRI studies in flank tumors. In the patient with metastatic ovarian cancer, the average pHe value of three adjacent tumors was 6.58, and the most reliable pHe measurements were obtained from the right posterior tumor, which favorably compared with DCE MRI and histopathological results. The average pHe of the kidney showed an average pHe of 6.73 units. The patient with high-grade invasive ductal carcinoma failed to accumulate sufficient agent to generate pHe measurements. CONCLUSIONS Optimized acidoCEST MRI generated pHe measurements in a flank tumor model and could be translated to the clinic to assess a patient with metastatic ovarian cancer.
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Affiliation(s)
- Kyle M Jones
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, USA
| | - Edward A Randtke
- Department of Medical Imaging, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724-5024, USA
| | | | - Christine M Howison
- Department of Medical Imaging, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724-5024, USA
| | - Pavani Chalasani
- Division of Hematology-Oncology, University of Arizona, Tucson, AZ, USA
| | - Robert R Klein
- Department of Pathology, University of Arizona, Tucson, AZ, USA
| | - Setsuko K Chambers
- University of Arizona Cancer Center, Tucson, AZ, USA.,Department of Obstetrics and Gynecology, University of Arizona, Tucson, AZ, USA
| | - Phillip H Kuo
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, USA.,Department of Medical Imaging, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724-5024, USA.,University of Arizona Cancer Center, Tucson, AZ, USA
| | - Mark D Pagel
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, USA. .,Department of Medical Imaging, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724-5024, USA. .,University of Arizona Cancer Center, Tucson, AZ, USA.
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17
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Burnett ME, Adebesin B, Ratnakar SJ, Green KN. Crystallographic Characterization and Non-Innocent Redox Activity of the Glycine Modified DOTA Scaffold and Its Impact on Eu III Electrochemistry. Eur J Inorg Chem 2018; 2018:1556-1562. [PMID: 30505213 PMCID: PMC6263031 DOI: 10.1002/ejic.201701398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 11/11/2022]
Abstract
EuDOTA-glycine derivatives have been explored as alternatives to typical gadolinium-containing complexes for MRI agents used in diagnostic imaging. Different imaging modalities can be accessed (T 1 or PARACEST) dependent on the oxidation state of the europium ion. Throughout the past 30 years, there have been significant manipulations and additions made to the DOTA scaffold; yet, characterizations related to electrochemistry and structure determined through XRD analysis have not been fully analyzed. In this work, electrochemical analysis using cyclic voltammetry was carried out on EuDOTA derivatives, including the free ligand DOTAGly4 (4) and the complexes. Effects of glycinate substitution on the DOTA scaffold, specifically, ligand interactions with the glassy carbon electrode were observed. A range of electrochemical investigations were carried out to show that increased glycinate substitution led to increased interaction with the electrode surface, thus implicating a new factor to consider when evaluating the electrochemistry of glycinate substituted ligands. In addition, the solid-state structure of EuDOTAGly4 (Eu4) was determined by X-ray diffraction and a brief analysis is presented compared to known Ln3+ structures found within literature. The Eu4 complex crystalizes in a rare polymer type arrangement via bridging side-arms between adjacent complexes.
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Affiliation(s)
- Marianne E Burnett
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 W. Bowie, Fort Worth, TX, 76129, USA, , http://chemistry.tcu.edu/staff/kayla-green/
| | - Bukola Adebesin
- Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75930, USA, , http://www.utsouthwestern.edu/education/medical-school/departments/airc/
| | - S James Ratnakar
- Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75930, USA, , http://www.utsouthwestern.edu/education/medical-school/departments/airc/
| | - Kayla N Green
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 W. Bowie, Fort Worth, TX, 76129, USA, , http://chemistry.tcu.edu/staff/kayla-green/
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18
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Thorarinsdottir AE, Du K, Collins JHP, Harris TD. Ratiometric pH Imaging with a CoII2 MRI Probe via CEST Effects of Opposing pH Dependences. J Am Chem Soc 2017; 139:15836-15847. [DOI: 10.1021/jacs.7b08574] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
| | - Kang Du
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - James H. P. Collins
- Advanced
Magnetic Resonance Imaging and Spectroscopy Facility, University of Florida, Gainesville, Florida 32611, United States
| | - T. David Harris
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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19
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Affiliation(s)
- KowsalyaDevi Pavuluri
- Russell H. Morgan Department of Radiology and Radiological Science; Johns Hopkins University School of Medicine; Baltimore, Maryland 21205 United States
| | - Michael T. McMahon
- Russell H. Morgan Department of Radiology and Radiological Science; Johns Hopkins University School of Medicine; Baltimore, Maryland 21205 United States
- F. M. Kirby Research Center for Functional Brain Imaging; Kennedy Krieger Research Institute; Baltimore, Maryland 21205 United States
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20
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Jones KM, Pollard AC, Pagel MD. Clinical applications of chemical exchange saturation transfer (CEST) MRI. J Magn Reson Imaging 2017; 47:11-27. [PMID: 28792646 DOI: 10.1002/jmri.25838] [Citation(s) in RCA: 184] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 05/30/2017] [Indexed: 02/06/2023] Open
Abstract
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has been developed and employed in multiple clinical imaging research centers worldwide. Selective radiofrequency (RF) saturation pulses with standard 2D and 3D MRI acquisition schemes are now routinely performed, and CEST MRI can produce semiquantitative results using magnetization transfer ratio asymmetry (MTRasym ) analysis while accounting for B0 inhomogeneity. Faster clinical CEST MRI acquisition methods and more quantitative acquisition and analysis routines are under development. Endogenous biomolecules with amide, amine, and hydroxyl groups have been detected during clinical CEST MRI studies, and exogenous CEST agents have also been administered to patients. These CEST MRI tools show promise for contributing to assessments of cerebral ischemia, neurological disorders, lymphedema, osteoarthritis, muscle physiology, and solid tumors. This review summarizes the salient features of clinical CEST MRI protocols and critically evaluates the utility of CEST MRI for these clinical imaging applications. LEVEL OF EVIDENCE 5 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:11-27.
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Affiliation(s)
- Kyle M Jones
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Mark D Pagel
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA.,Department of Chemistry, Rice University, Houston, Texas, USA.,Department of Cancer Systems Imaging, MD Anderson Cancer Center, Houston, Texas, USA
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21
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Wu Y, Zhou IY, Igarashi T, Longo DL, Aime S, Sun PZ. A generalized ratiometric chemical exchange saturation transfer (CEST) MRI approach for mapping renal pH using iopamidol. Magn Reson Med 2017; 79:1553-1558. [PMID: 28686805 DOI: 10.1002/mrm.26817] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 06/06/2017] [Accepted: 06/11/2017] [Indexed: 12/21/2022]
Abstract
PURPOSE To extend the pH detection range of iopamidol-based ratiometric chemical exchange saturation transfer (CEST) MRI at sub-high magnetic field and establish quantitative renal pH MRI. METHODS Chemical exchange saturation transfer imaging was performed on iopamidol phantoms with pH of 5.5 to 8.0 and in vivo on rat kidneys (n = 5) during iopamidol administration at a 4.7 T. Iopamidol CEST effects were described using a multipool Lorentzian model. A generalized ratiometric analysis was conducted by ratioing resolved iopamidol CEST effects at 4.3 and 5.5 ppm obtained under 1.0 and 2.0 µT, respectively. The pH detection range was established for both the standard ratiometric analysis and the proposed resolved approach. Renal pH was mapped in vivo with regional pH assessed by one-way analysis of variance. RESULTS Good-fitting performance was observed in multipool Lorentzian resolving of CEST effects (R2 s > 0.99). The proposed approach extends the in vitro pH detection range to 5.5 to 7.5 at 4.7 T. In vivo renal pH was measured to be 7.0 ± 0.1, 6.8 ± 0.1, and 6.5 ± 0.2 for cortex, medulla and calyx, respectively (P < 0.05). CONCLUSIONS The proposed ratiometric approach extended the iopamidol pH detection range, enabling the renal pH mapping in vivo, which is promising for pH imaging studies at sub-high or low fields with potential clinical applicability. Magn Reson Med 79:1553-1558, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Yin Wu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA.,Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Key Laboratory for MRI, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Iris Y Zhou
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| | - Takahiro Igarashi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| | - Dario L Longo
- Institute of Biostructure and Bioimaging (CNR) c/o Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Silvio Aime
- Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center, University of Torino, Torino, Italy
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
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22
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Sinharay S, Howison CM, Baker AF, Pagel MD. Detecting in vivo urokinase plasminogen activator activity with a catalyCEST MRI contrast agent. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3721. [PMID: 28370884 PMCID: PMC5704996 DOI: 10.1002/nbm.3721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 02/04/2017] [Accepted: 02/06/2017] [Indexed: 05/22/2023]
Abstract
Urokinase plasminogen activator (uPA) promotes tumor invasion and metastasis. The monitoring of uPA activity using molecular imaging may have prognostic value and be predictive for response to anti-cancer therapies. However, the detection of in vivo enzyme activity with molecular imaging remains a challenge. To address this problem, we designed a nonmetallic contrast agent, GR-4Am-SA, that can be detected with chemical exchange saturation transfer (CEST) MRI. This agent has a peptide that is cleaved by uPA, which causes a CEST signal at 5.0 ppm to decrease, and also has a salicylic acid moiety that can produce a CEST signal at 9.5 ppm, which is largely unresponsive to enzyme activity. The two CEST signals were used to determine a reaction coordinate, representing the extent of enzyme-catalyzed cleavage of the GR-4Am-SA agent during an experimental study. Initial biochemical studies showed that GR-4Am-SA could detect uPA activity in reducing conditions. Subsequently, we used our catalyCEST MRI protocol with the agent to detect the uPA catalysis of GR-4Am-SA in a flank xenograft model of Capan-2 pancreatic cancer. The results showed an average reaction coordinate of 80% ± 8%, which was strongly dependent on the CEST signal at 5.0 ppm. The relative independence of the reaction coordinate on the CEST signal at 9.5 ppm showed that the detection of enzyme activity was largely independent of the concentration of GR-4Am-SA within the tumor tissue. These results demonstrated the advantages of a single CEST agent with biomarker-responsive and unresponsive signals for reliably assessing enzyme activity during in vivo cancer studies.
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Affiliation(s)
- Sanhita Sinharay
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
| | | | - Amanda F. Baker
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ
| | - Mark D. Pagel
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ
- Department of Medical Imaging, University of Arizona, Tucson, AZ
- Corresponding Author: Mark D. Pagel, University of Arizona Cancer Center, 1515 N. Campbell Avenue, Tucson, AZ 85724-5024, Tel: (520)-404-7049, Fax: (520)-626-0395,
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23
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Hundshammer C, Düwel S, Schilling F. Imaging of Extracellular pH Using Hyperpolarized Molecules. Isr J Chem 2017. [DOI: 10.1002/ijch.201700017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Christian Hundshammer
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
- Department of Chemistry; Technical University of Munich; Lichtenbergstr. 2 85748 Garching Germany
| | - Stephan Düwel
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
- Department of Chemistry; Technical University of Munich; Lichtenbergstr. 2 85748 Garching Germany
- Institute of Medical Engineering; Technical University of Munich; Boltzmannstr. 11 85748 Garching Germany
| | - Franz Schilling
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
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24
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Daryaei I, Jones KM, Pagel MD. Detection of DT-diaphorase Enzyme with a ParaCEST MRI Contrast Agent. Chemistry 2017; 23:6514-6517. [PMID: 28370655 DOI: 10.1002/chem.201700721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 12/26/2022]
Abstract
A responsive magnetic resonance (MRI) contrast agent has been developed that can detect the enzyme activity of DT-diaphorase. The agent produced different chemical exchange saturation transfer (CEST) MRI signals before and after incubation with the enzyme, NADH, and GSH at different pH values whereas it showed good stability in a reducing environment without enzyme.
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Affiliation(s)
- Iman Daryaei
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Room 221, Tucson, Arizona, 85721-0041, USA
| | - Kyle M Jones
- Department of Biomedical Engineering, University of Arizona, 1127 E James E. Rogers Way P.O. Box 210020, Tucson, AZ, 85721-0020, USA
| | - Mark D Pagel
- Department of Medical Imaging, University of Arizona, 1501 N. Campbell, P.O. Box 245067, Tucson, Arizona, 85724, USA
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25
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Tsitovich PB, Cox JM, Spernyak JA, Morrow JR. Gear Up for a pH Shift: A Responsive Iron(II) 2-Amino-6-picolyl-Appended Macrocyclic paraCEST Agent That Protonates at a Pendent Group. Inorg Chem 2016; 55:12001-12010. [PMID: 27934305 DOI: 10.1021/acs.inorgchem.6b02159] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Two high-spin Fe(II) and Co(II) complexes of 1,4,7,10-tetraazacyclododecane (CYCLEN) appended with four 2-amino-6-picolyl groups, denoted as [Fe(TAPC)]2+ and [Co(TAPC)]2+, are reported. These complexes demonstrate C2-symmetrical geometry from coordination of two pendents, and they are present in a single diastereomeric form in aqueous solution as shown by 1H NMR spectroscopy and by a single-crystal X-ray structure for the Co(II) complex. A highly shifted but low-intensity CEST (chemical exchange saturation transfer) signal from NH groups is observed at -118 ppm for [Co(TAPC)]2+ at pH 6.0 and 37 °C. A higher intensity CEST peak is observed for [Fe(TAPC)]2+, which demonstrates a pH-dependent frequency shift from -72 to -79 ppm at pH 7.7 to 4.8, respectively, at 37 °C. This shift in the CEST peak correlates with the protonation of the unbound 2-amino-6-picolyl pendents, as suggested by UV-vis and 1H NMR spectroscopy studies at different pH values. Phantom imaging demonstrates the challenges and feasibility of using the [Fe(TAPC)]2+ agent on a low-field MRI scanner. The [Fe(TAPC)]2+ complex is the first transition-metal-based paraCEST agent that produces a pH-induced CEST frequency change toward the development of probes for concentration-independent imaging of pH.
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Affiliation(s)
- Pavel B Tsitovich
- Department of Chemistry, University at Buffalo, the State University of New York , Buffalo, New York 14260, United States
| | - Jordan M Cox
- Department of Chemistry, University at Buffalo, the State University of New York , Buffalo, New York 14260, United States
| | - Joseph A Spernyak
- Department of Cell Stress Biology, Roswell Park Cancer Institute , Buffalo, New York 14263, United States
| | - Janet R Morrow
- Department of Chemistry, University at Buffalo, the State University of New York , Buffalo, New York 14260, United States
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26
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Drachman N, Kadlecek S, Pourfathi M, Xin Y, Profka H, Rizi R. In vivo pH mapping of injured lungs using hyperpolarized [1- 13 C]pyruvate. Magn Reson Med 2016; 78:1121-1130. [PMID: 27714832 DOI: 10.1002/mrm.26473] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/26/2016] [Accepted: 08/29/2016] [Indexed: 12/21/2022]
Abstract
PURPOSE To optimize the production of hyperpolarized 13 C-bicarbonate from the decarboxylation of hyperpolarized [1-13 C]pyruvate and use it to image pH in the lungs and heart of rats with acute lung injury. METHODS Two forms of catalysis are compared calorimetrically to maximize the rate of decarboxylation and rapidly produce hyperpolarized bicarbonate from pyruvate while minimizing signal loss. Rats are injured using an acute lung injury model combining ventilator-induced lung injury and acid aspiration. Carbon images are obtained from both healthy (n = 4) and injured (n = 4) rats using a slice-selective chemical shift imaging sequence with low flip angle. pH is calculated from the relative HCO3- and CO2 signals using the Henderson-Hasselbalch equation. RESULTS It is demonstrated that base catalysis is more effective than metal-ion catalysis for this decarboxylation reaction. Bicarbonate polarizations up to 17.2% are achieved using the base-catalyzed reaction. A mean pH difference between lung and heart of 0.14 pH units is measured in the acute lung injury model. A significant pH difference between injured and uninjured lungs is also observed. CONCLUSION It is demonstrated that hyperpolarized 13 C-bicarbonate can be efficiently produced from the base-catalyzed decarboxylation of pyruvate. This method is used to obtain the first regional pH image of the lungs and heart of an animal. Magn Reson Med 78:1121-1130, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Nicholas Drachman
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rahim Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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27
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Randtke EA, Granados JC, Howison CM, Pagel MD, Cárdenas-Rodríguez J. Multislice CEST MRI improves the spatial assessment of tumor pH. Magn Reson Med 2016; 78:97-106. [PMID: 27465207 DOI: 10.1002/mrm.26348] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/25/2016] [Accepted: 06/28/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE Multislice maps of extracellular pH (pHe) are needed to interrogate the heterogeneities of tumors and normal organs. To address this need, we have developed a multislice chemical exchange saturation transfer (CEST) MRI acquisition method with a CEST spectrum-fitting method that measures in vivo pHe over a range of 6.3 to 7.4. METHODS The phase offset multiplanar (POMP) method was adapted for CEST fast imaging with steady-state free precession (FISP) MRI to acquire multiple image slices with a single CEST saturation pulse. The Bloch-McConnell equations were modified to include pH based on a calibration of pH and chemical exchange rate for the contrast agent iopamidol. These equations were used to estimate the pixel-wise pHe values throughout the multislice acidoCEST MR images of the tumor, kidney, bladder, and other tissues of a MDA-MB-231 tumor model. RESULTS Multislice acidoCEST MRI successfully mapped a gradient of pHe from 6.73 to 6.81 units from the tumor core to rim, and also mapped a gradient of pHe 6.56 to 6.97 across the mouse kidney. The bladder was found to be pHe 6.3. CONCLUSION AcidoCEST MRI with POMP acquisition and Bloch-McConnel analysis can map pHe in multiple imaging slices through the tumor, kidney, and bladder. This multislice evaluation facilitates assessments of spatial heterogeneity of tissue pHe. Magn Reson Med 78:97-106, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Edward A Randtke
- Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA
| | - Jeffry C Granados
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Mark D Pagel
- Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA
| | - Julio Cárdenas-Rodríguez
- Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA.,Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA
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28
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Ngen EJ, Bar-Shir A, Jablonska A, Liu G, Song X, Ansari R, Bulte JWM, Janowski M, Pearl M, Walczak P, Gilad AA. Imaging the DNA Alkylator Melphalan by CEST MRI: An Advanced Approach to Theranostics. Mol Pharm 2016; 13:3043-53. [PMID: 27398883 DOI: 10.1021/acs.molpharmaceut.6b00130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Brain tumors are among the most lethal types of tumors. Therapeutic response variability and failure in patients have been attributed to several factors, including inadequate drug delivery to tumors due to the blood-brain barrier (BBB). Consequently, drug delivery strategies are being developed for the local and targeted delivery of drugs to brain tumors. These drug delivery strategies could benefit from new approaches to monitor the delivery of drugs to tumors. Here, we evaluated the feasibility of imaging 4-[bis(2-chloroethyl)amino]-l-phenylalanine (melphalan), a clinically used DNA alkylating agent, using chemical exchange saturation transfer magnetic resonance imaging (CEST MRI), for theranostic applications. We evaluated the physicochemical parameters that affect melphalan's CEST contrast and demonstrated the feasibility of imaging the unmodified drug by saturating its exchangeable amine protons. Melphalan generated a CEST signal despite its reactivity in an aqueous milieu. The maximum CEST signal was observed at pH 6.2. This CEST contrast trend was then used to monitor therapeutic responses to melphalan in vitro. Upon cell death, the decrease in cellular pH from ∼7.4 to ∼6.4 caused an amplification of the melphalan CEST signal. This is contrary to what has been reported for other CEST contrast agents used for imaging cell death, where a decrease in the cellular pH following cell death results in a decrease in the CEST signal. Ultimately, this method could be used to noninvasively monitor melphalan delivery to brain tumors and also to validate therapeutic responses to melphalan clinically.
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Affiliation(s)
- Ethel J Ngen
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States
| | - Amnon Bar-Shir
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States
| | - Anna Jablonska
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States
| | - Guanshu Liu
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States
| | - Xiaolei Song
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States
| | | | - Jeff W M Bulte
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States
| | - Miroslaw Janowski
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,NeuroRepair Department, Mossakowski Medical Research Centre, PAS , 02106 Warsaw, Poland.,Department of Neurosurgery, Mossakowski Medical Research Centre, PAS , 02106 Warsaw, Poland
| | - Monica Pearl
- Division of Interventional Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Department of Radiology, Children's National Medical Center , Washington, D.C. 20010, United States
| | - Piotr Walczak
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Department of Radiology, Faculty of Medical Sciences, University of Warmia and Mazury , Olsztyn, Poland
| | - Assaf A Gilad
- Division of Magnetic Resonance Research, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute , Baltimore, Maryland 21205, United States
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Sinharay S, Pagel MD. Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:95-115. [PMID: 27049630 PMCID: PMC4911245 DOI: 10.1146/annurev-anchem-071015-041514] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Recent advances in magnetic resonance imaging (MRI) contrast agents have provided new capabilities for biomarker detection through molecular imaging. MRI contrast agents based on the T2 exchange mechanism have more recently expanded the armamentarium of agents for molecular imaging. Compared with T1 and T2* agents, T2 exchange agents have a slower chemical exchange rate, which improves the ability to design these MRI contrast agents with greater specificity for detecting the intended biomarker. MRI contrast agents that are detected through chemical exchange saturation transfer (CEST) have even slower chemical exchange rates. Another emerging class of MRI contrast agents uses hyperpolarized (13)C to detect the agent with outstanding sensitivity. These hyperpolarized (13)C agents can be used to track metabolism and monitor characteristics of the tissue microenvironment. Together, these various MRI contrast agents provide excellent opportunities to develop molecular imaging for biomarker detection.
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Affiliation(s)
- Sanhita Sinharay
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85724;
| | - Mark D Pagel
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85724;
- Department of Medical Imaging, University of Arizona, Tucson, Arizona 85724;
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Sinharay S, Randtke EA, Jones KM, Howison CM, Chambers SK, Kobayashi H, Pagel MD. Noninvasive detection of enzyme activity in tumor models of human ovarian cancer using catalyCEST MRI. Magn Reson Med 2016; 77:2005-2014. [PMID: 27221386 DOI: 10.1002/mrm.26278] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/25/2016] [Accepted: 04/25/2016] [Indexed: 12/17/2022]
Abstract
PURPOSE We proposed to detect the in vivo enzyme activity of γ-glutamyl transferase (GGT) within mouse models of human ovarian cancers using catalyCEST MRI with a diamagnetic CEST agent. METHODS A CEST-FISP MRI protocol and a diamagnetic CEST agent were developed to detect GGT enzyme activity in biochemical solution. A quantitative Michaelis-Menten enzyme kinetics study was performed to confirm that catalyCEST MRI can measure enzyme activity. In vivo catalyCEST MRI studies generated pixel-wise activity maps of GGT activities. Ex vivo fluorescence imaging was performed for validation. RESULTS CatalyCEST MRI selectively detected two CEST signals from a single CEST agent, whereby one CEST signal was responsive to GGT enzyme activity and the other CEST signal was an unresponsive control signal. The comparison of these CEST signals facilitated in vivo catalyCEST MRI studies that detected high GGT activity in OVCAR-8 tumors, low GGT activity in OVCAR-3 tumors, and low or no GGT activity in muscle tissues. CONCLUSION CatalyCEST MRI with a diamagnetic CEST agent can detect the level of GGT enzyme activity within in vivo tumor models of human ovarian cancers. Magn Reson Med 77:2005-2014, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Sanhita Sinharay
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - Edward A Randtke
- Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA
| | - Kyle M Jones
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, Arizona, USA
| | | | - Setsuko K Chambers
- Department of Obstetrics and Gynecology, University of Arizona, Tucson, Arizona, USA.,University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
| | - Hisataka Kobayashi
- Laboratory of Molecular Theranostics, National Cancer Institute, NIH, Bethesda, Maryland, USA
| | - Mark D Pagel
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA.,Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA.,University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
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Jones KM, Randtke EA, Howison CM, Pagel MD. Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9788. [PMID: 27212783 DOI: 10.1117/12.2216418] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion.
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Affiliation(s)
- Kyle M Jones
- Biomedical Engineering, University of Arizona, Tucson, AZ
| | - Edward A Randtke
- Department of Medical Imaging, University of Arizona, Tucson, AZ; Cancer Biology Program
| | - Christine M Howison
- Department of Medical Imaging, University of Arizona, Tucson, AZ; Cancer Biology Program
| | - Mark D Pagel
- Biomedical Engineering, University of Arizona, Tucson, AZ; Department of Medical Imaging, University of Arizona, Tucson, AZ; Cancer Biology Program; University of Arizona Cancer Center, Tucson, AZ
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Fernández-Cuervo G, Sinharay S, Pagel MD. A CatalyCEST MRI Contrast Agent that Can Simultaneously Detect Two Enzyme Activities. Chembiochem 2016; 17:383-7. [PMID: 26693680 PMCID: PMC4814164 DOI: 10.1002/cbic.201500586] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 12/28/2022]
Abstract
The simultaneous detection of multiple enzyme activities can improve the specificity of disease diagnoses. We therefore synthesized and characterized a diamagnetic chemical exchange saturation transfer (CEST) MRI contrast agent that can simultaneously detect two enzyme activities. Sulfatase and esterase enzymes cleave the ligands of the CEST agent, releasing salicylic acid that can be detected with CEST MRI. Importantly, both enzymes are required to activate the agent to produce a CEST MRI contrast, and the CEST agent was stable without enzyme treatment. These results established that this diamagnetic CEST MRI contrast agent is a platform technology with a modular design that can be potentially exploited to detect other combinations of enzyme activities, which can expand the armamentarium of contrast agents for molecular imaging.
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Affiliation(s)
- Gabriela Fernández-Cuervo
- Department of Pharmaceutical Sciences, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Sanhita Sinharay
- Department of Chemistry and Biochemistry, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Mark D Pagel
- Department of Medical Imaging, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA.
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Moon BF, Jones KM, Chen LQ, Liu P, Randtke EA, Howison CM, Pagel MD. A comparison of iopromide and iopamidol, two acidoCEST MRI contrast media that measure tumor extracellular pH. CONTRAST MEDIA & MOLECULAR IMAGING 2015; 10:446-55. [PMID: 26108564 PMCID: PMC4691225 DOI: 10.1002/cmmi.1647] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/30/2015] [Accepted: 04/20/2015] [Indexed: 11/09/2022]
Abstract
Acidosis within tumor and kidney tissues has previously been quantitatively measured using a molecular imaging technique known as acidoCEST MRI. The previous studies used iopromide and iopamidol, two iodinated contrast agents that are approved for clinical CT diagnoses and have been repurposed for acidoCEST MRI studies. We aimed to compare the performance of the two agents for measuring pH by optimizing image acquisition conditions, correlating pH with a ratio of CEST effects from an agent, and evaluating the effects of concentration, endogenous T1 relaxation time and temperature on the pH-CEST ratio correlation for each agent. These results showed that the two agents had similar performance characteristics, although iopromide produced a pH measurement with a higher dynamic range while iopamidol produced a more precise pH measurement. We then compared the performance of the two agents to measure in vivo extracellular pH (pHe) within xenograft tumor models of Raji lymphoma and MCF-7 breast cancer. Our results showed that the pHe values measured with each agent were not significantly different. Also, iopromide consistently measured a greater region of the tumor relative to iopamidol in both tumor models. Therefore, an iodinated contrast agent for acidoCEST MRI should be selected based on the measurement properties needed for a specific biomedical study and the pharmacokinetic properties of a specific tumor model.
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Affiliation(s)
- Brianna F. Moon
- Department of Biomedical Engineering, University of Arizona, Tucson AZ
| | - Kyle M. Jones
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson AZ
| | - Liu Qi Chen
- Department of Chemistry & Biochemistry, University of Arizona, Tucson AZ
| | - Peilu Liu
- Department of Chemistry & Biochemistry, University of Arizona, Tucson AZ
| | - Edward A. Randtke
- Department of Biomedical Engineering, University of Arizona, Tucson AZ
| | | | - Mark D. Pagel
- Department of Biomedical Engineering, University of Arizona, Tucson AZ
- Department of Chemistry & Biochemistry, University of Arizona, Tucson AZ
- Department of Medical Imaging, University of Arizona, Tucson AZ
- University of Arizona Cancer Center, University of Arizona, Tucson AZ
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Kimbrough CW, Khanal A, Zeiderman M, Khanal BR, Burton NC, McMasters KM, Vickers SM, Grizzle WE, McNally LR. Targeting Acidity in Pancreatic Adenocarcinoma: Multispectral Optoacoustic Tomography Detects pH-Low Insertion Peptide Probes In Vivo. Clin Cancer Res 2015; 21:4576-85. [PMID: 26124201 PMCID: PMC4609270 DOI: 10.1158/1078-0432.ccr-15-0314] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/12/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND pH-low insertion peptides (pHLIP) can serve as a targeting moiety that enables pH-sensitive probes to detect solid tumors. Using these probes in conjunction with multispectral optoacoustic tomography (MSOT) is a promising approach to improve imaging for pancreatic cancer. METHODS A pH-sensitive pHLIP (V7) was conjugated to 750 NIR fluorescent dye and evaluated as a targeted probe for pancreatic adenocarcinoma. The pH-insensitive K7 pHLIP served as an untargeted control. Probe binding was assessed in vitro at pH 7.4, 6.8, and 6.6 using human pancreatic cell lines S2VP10 and S2013. Using MSOT, semiquantitative probe accumulation was then assessed in vivo with a murine orthotopic pancreatic adenocarcinoma model. RESULTS In vitro, the V7-750 probe demonstrated significantly higher fluorescence at pH 6.6 compared with pH 7.4 (S2VP10, P = 0.0119; S2013, P = 0.0160), whereas no difference was observed with the K7-750 control (S2VP10, P = 0.8783; S2013, P = 0.921). In the in vivo S2VP10 model, V7-750 probe resulted in 782.5 MSOT a.u. signal compared with 5.3 MSOT a.u. in K7-750 control in tumor (P = 0.0001). Similarly, V7-750 probe signal was 578.3 MSOT a.u. in the S2013 model compared with K7-750 signal at 5.1 MSOT a.u. (P = 0.0005). There was minimal off-target accumulation of the V7-750 probe within the liver or kidney, and probe distribution was confirmed with ex vivo imaging. CONCLUSIONS Compared with pH-insensitive controls, V7-750 pH-sensitive probe specifically targets pancreatic adenocarcinoma and has minimal off-target accumulation. The noninvasive detection of pH-targeted probes by means of MSOT represents a promising modality to improve the detection and monitoring of pancreatic cancer.
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Affiliation(s)
- Charles W Kimbrough
- The Hiram C. Polk Jr, MD Department of Surgery, University of Louisville, Louisville, Kentucky
| | - Anil Khanal
- Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Matthew Zeiderman
- The Hiram C. Polk Jr, MD Department of Surgery, University of Louisville, Louisville, Kentucky
| | - Bigya R Khanal
- Department of Medicine, University of Louisville, Louisville, Kentucky
| | | | - Kelly M McMasters
- The Hiram C. Polk Jr, MD Department of Surgery, University of Louisville, Louisville, Kentucky
| | | | | | - Lacey R McNally
- Department of Medicine, University of Louisville, Louisville, Kentucky.
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Yoo B, Sheth VR, Howison CM, Douglas MJK, Pineda CT, Maine EA, Baker AF, Pagel MD. Detection of in vivo enzyme activity with CatalyCEST MRI. Magn Reson Med 2015; 71:1221-30. [PMID: 23640714 DOI: 10.1002/mrm.24763] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE CatalyCEST MRI compares the detection of an enzyme-responsive chemical exchange saturation transfer (CEST) agent with the detection of an unresponsive "control" CEST agent that accounts for other conditions that influence CEST. The purpose of this study was to investigate the feasibility of in vivo catalyCEST MRI. METHODS CEST agents that were responsive and unresponsive to the activity of urokinase plasminogen activator were shown to have negligible interaction with each other. A CEST-fast imaging with steady state precession (FISP) MRI protocol was used to acquire MR CEST spectroscopic images with a Capan-2 pancreatic tumor model after intravenous injection of the CEST agents. A function of (super)-Lorentzian line shapes was fit to CEST spectra of a region-of-interest that represented the tumor. RESULTS The CEST effects from each agent showed the same initial uptake into tumor tissues, indicating that both agents had the same pharmacokinetic transport rates. Starting 5 min after injection, CEST from the enzyme-responsive agent disappeared more quickly than CEST from the unresponsive agent, indicating that the enzyme responsive agent was being catalyzed by urokinase plasminogen activator, while both agents also experienced net pharmacokinetic washout from the tumor. CONCLUSION CatalyCEST MRI demonstrates that dynamic tracking of enzyme-responsive and unresponsive CEST agents during the same in vivo MRI study is feasible.
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Affiliation(s)
- Byunghee Yoo
- MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Kuda-Wedagedara ANW, Allen MJ. Enhancing magnetic resonance imaging with contrast agents for ultra-high field strengths. Analyst 2015; 139:4401-10. [PMID: 25054827 DOI: 10.1039/c4an00990h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Contrast agents are diagnostic tools that often complement magnetic resonance imaging. At ultra-high field strengths (≥7 T), magnetic resonance imaging is capable of generating desirable high signal-to-noise ratios, but clinically available contrast agents are less effective at ultra-high field strengths relative to lower fields. This gap in effectiveness demands the development of contrast agents for ultra-high field strengths. In this minireview, we summarize contrast agents reported during the last three years that focused on ultra-high field strengths.
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Evaluating pH in the Extracellular Tumor Microenvironment Using CEST MRI and Other Imaging Methods. ACTA ACUST UNITED AC 2015; 2015. [PMID: 27761517 DOI: 10.1155/2015/206405] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tumor acidosis is a consequence of altered metabolism, which can lead to chemoresistance and can be a target of alkalinizing therapies. Noninvasive measurements of the extracellular pH (pHe) of the tumor microenvironment can improve diagnoses and treatment decisions. A variety of noninvasive imaging methods have been developed for measuring tumor pHe. This review provides a detailed description of the advantages and limitations of each method, providing many examples from previous research reports. A substantial emphasis is placed on methods that use MR spectroscopy and MR imaging, including recently developed methods that use chemical exchange saturation transfer MRI that combines some advantages of MR spectroscopy and imaging. Together, this review provides a comprehensive overview of methods for measuring tumor pHe, which may facilitate additional creative approaches in this research field.
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Chen LQ, Howison CM, Spier C, Stopeck AT, Malm SW, Pagel MD, Baker AF. Assessment of carbonic anhydrase IX expression and extracellular pH in B-cell lymphoma cell line models. Leuk Lymphoma 2015; 56:1432-9. [PMID: 25130478 PMCID: PMC4697737 DOI: 10.3109/10428194.2014.933218] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The expression of carbonic anhydrase IX (CA IX) and its relationship to acidosis in lymphomas has not been widely studied. We investigated the protein expression of CA IX in a human B-cell lymphoma tissue microarray, and in Raji, Ramos and Granta 519 lymphoma cell lines and tumor models, while also investigating the relationship with hypoxia. An imaging method, acidoCEST magnetic resonance imaging (MRI), was used to estimate lymphoma xenograft extracellular pH (pHe). Our results showed that clinical lymphoma tissues and cell line models in vitro and in vivo had moderate CA IX expression. Although in vitro studies showed that CA IX expression was induced by hypoxia, in vivo studies did not show this correlation. Untreated lymphoma xenograft tumor pHe had acidic fractions, and an acidity score was qualitatively correlated with CA IX expression. Therefore, CA IX is expressed in B-cell lymphomas and is qualitatively correlated with extracellular acidosis in xenograft tumor models.
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Affiliation(s)
- Liu Qi Chen
- University of Arizona, Department of Chemistry and Biochemistry
| | | | - Catherine Spier
- University of Arizona, Department of Pathology, College of Medicine
| | - Alison T. Stopeck
- University of Arizona Cancer Center, Section of Hematology & Oncology, Department of Medicine
| | - Scott W. Malm
- University of Arizona, Department of Pharmacology/Toxicology, College of Pharmacy
| | - Mark D. Pagel
- University of Arizona, Department of Chemistry and Biochemistry, Biomedical Engineering, Medical Imaging, and University of Arizona Cancer Center
| | - Amanda F. Baker
- University of Arizona Cancer Center, Section of Hematology & Oncology, Department of Medicine,Corresponding Author: Amanda Baker, Pharm.D., Ph.D., 1515 N. Campbell Ave., Room 3977A, Tucson, AZ, 85724, Tel: (520)-626-0301, Fax: (520)-626-0395,
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Jones KM, Randtke EA, Howison CM, Cárdenas-Rodríguez J, Sime PJ, Kottmann RM, Pagel MD. Measuring extracellular pH in a lung fibrosis model with acidoCEST MRI. Mol Imaging Biol 2015; 17:177-84. [PMID: 25187227 PMCID: PMC4832114 DOI: 10.1007/s11307-014-0784-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE A feed-forward loop involving lactic acid production may potentially occur during the formation of idiopathic pulmonary fibrosis. To provide evidence for this feed-forward loop, we used acidoCEST MRI to measure the extracellular pH (pHe), while also measuring percent uptake of the contrast agent, lesion size, and the apparent diffusion coefficient (ADC). PROCEDURES We developed a respiration-gated version of acidoCEST MRI to improve the measurement of pHe and percent uptake in lesions. We also used T2-weighted MRI to measure lesion volumes and diffusion-weighted MRI to measure ADC. RESULTS The longitudinal changes in average pHe and % uptake of the contrast agent were inversely related to reduction in lung lesion volume. The average ADC did not change during the time frame of the study. CONCLUSIONS The increase in pHe during the reduction in lesion volume indicates a role for lactic acid in the proposed feed-forward loop of IPF.
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Affiliation(s)
- Kyle M. Jones
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ
| | - Edward A. Randtke
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
| | | | | | - Patricia J. Sime
- Department of Medicine, Pulmonary Diseases and Critical Care, University of Rochester, Rochester, NY
| | - R. Matthew Kottmann
- Department of Medicine, Pulmonary Diseases and Critical Care, University of Rochester, Rochester, NY
| | - Mark D. Pagel
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ
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Chen LQ, Howison CM, Jeffery JJ, Robey IF, Kuo PH, Pagel MD. Evaluations of extracellular pH within in vivo tumors using acidoCEST MRI. Magn Reson Med 2014; 72:1408-17. [PMID: 24281951 PMCID: PMC4033731 DOI: 10.1002/mrm.25053] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 10/26/2013] [Accepted: 10/28/2013] [Indexed: 11/07/2022]
Abstract
PURPOSE A practical, noninvasive method is needed to measure the extracellular pH (pHe) within in vivo tumors to longitudinally monitor tumor acidosis. We have optimized a biomedical imaging method, termed acidoCEST MRI, to provide noninvasive assessments of tumor pHe in preclinical models of mammary carcinoma. METHODS A CEST-FISP MRI method was optimized to detect the chemical exchange saturation transfer (CEST) of two amide protons of a clinically approved CT contrast agent, iopromide. The ratio of the two CEST effects was used to measure pH. Routes of administration of iopromide were evaluated to ensure sufficient delivery of the agent to the tumor. The optimized acidoCEST MRI method was then used to evaluate the change in tumor pHe following alkalinizing bicarbonate treatment. RESULTS The acidoCEST MRI protocol measured pH between 6.2 and 7.2 pH units. Greater delivery of iopromide was shown to improve the precision of the measurement of tumor pHe, but the agent did not influence the tumor pHe. AcidoCEST MRI was used to longitudinally monitor the effect of bicarbonate treatment on the pHe of tumors and bladders. CONCLUSION This study demonstrates that an optimized acidoCEST MRI method is a practical, noninvasive method for assessing changes in tumor acidosis.
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Affiliation(s)
- Liu Qi Chen
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | | | - Justin J. Jeffery
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
| | - Ian F. Robey
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
- Department of Medicine, University of Arizona, Tucson, AZ, USA
| | - Phillip H. Kuo
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA
| | - Mark D. Pagel
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA
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Krchová T, Kotek J, Jirák D, Havlíčková J, Císařová I, Hermann P. Lanthanide(III) complexes of aminoethyl-DO3A as PARACEST contrast agents based on decoordination of the weakly bound amino group. Dalton Trans 2014; 42:15735-47. [PMID: 24051547 DOI: 10.1039/c3dt52031e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2-Aminoethyl DOTA analogues with unsubstituted (H3L1), monomethylated (H3L2) and dimethylated (H3L3) amino groups were prepared by improved synthetic procedures. Their solid-state structures exhibit an extensive system of intramolecular hydrogen bonds, which is probably present in solution and leads to the rather high value of the last dissociation constant. The protonation sequence of H3L1 in solution corresponds to that found in the solid state. The stability constants of the H3L1 complexes with La(3+) and Gd(3+) (20.02 and 22.23, respectively) are similar to those of DO3A and the reduction of the pK(A) value of the pendant amino group from 10.51 in the free ligand to 6.06 and 5.83 in the La(3+) and Gd(3+) complexes, respectively, points to coordination of the amino group. It was confirmed in the solid state structure of the [Yb(L1)] complex, where disorder between the SA' and TSA' isomers was found. A similar situation is expected in solution, where a fast equilibration among the isomers hampers the unambiguous determination of the isomer ratio in solution. The PARACEST effect was observed in Eu(III)-H3L1/H3L2 and Yb(III)-H3L1/H3L2 complexes, being dependent on pH in the region of 4.5-7.5 and pH-independent in more alkaline solutions. The decrease of the PARACEST effect parallels with the increasing abundance of the complex protonated species, where the pendant amino group is not coordinating. Surprisingly, a small PARACEST effect was also observed in solutions of Eu(III)/Yb(III)-H3L3 complexes, where the pendant amino group is dimethylated. The effect is detectable in a narrow pH region, where both protonated and deprotonated complex species are present in equilibrium. The data points to the new mechanism of the PARACEST effect, where the slow coordination-decoordination of the pendant amine is coupled with the fast proton exchange between the free amino group and bulk water mediates the magnetization transfer. The pH-dependence of the effect was proved to be measurable by MRI and, thus, the complexes extend the family of pH-sensitive probes.
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Affiliation(s)
- Tereza Krchová
- Department of Inorganic Chemistry, Universita Karlova (Charles University), Hlavova 2030, 128 40 Prague 2, Czech Republic.
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Randtke EA, Chen LQ, Pagel MD. The reciprocal linear QUEST analysis method facilitates the measurements of chemical exchange rates with CEST MRI. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:252-8. [PMID: 24700753 PMCID: PMC3980514 DOI: 10.1002/cmmi.1566] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/28/2013] [Accepted: 08/01/2013] [Indexed: 11/10/2022]
Abstract
Magnetic resonance imaging (MRI) contrast media that are detected via chemical exchange saturation transfer (CEST) often require an accurate estimation of their chemical exchange rate, kex . A variety of analysis methods have been proposed to estimate kex , including the nonlinear QUEST analysis method that evaluates the CEST amplitude as a function of saturation time. We have derived a linear version of QUEST, termed the Reciprocal Linear QUEST (RL-QUEST) method. Our simulations and experimental results show that RL-QUEST performs as well as QUEST, while providing a more simplistic fitting procedure. Although CEST results should be acquired with saturation power that has a nutation rate that is faster than kex of the CEST agent, an exact determination of the saturation power is not required to accurately estimate kex with RL-QUEST. This new analysis method requires a determination of the CEST agent's concentration, which is straightforward for the analysis of CEST agents in chemical solutions, but may be a limitation during in vivo CEST MRI studies. Based on the results of this study and previous studies, we provide recommendations for the linear analysis method that should be employed for each type of CEST MRI study.
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Affiliation(s)
- Edward A. Randtke
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
| | - Liu Qi Chen
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
| | - Mark D. Pagel
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ
- Department of Medical Imaging, University of Arizona, Tucson, AZ
- University of Arizona Cancer Center, Tucson, AZ
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Goodwin J, Yachi K, Nagane M, Yasui H, Miyake Y, Inanami O, Bobko AA, Khramtsov VV, Hirata H. In vivo tumour extracellular pH monitoring using electron paramagnetic resonance: the effect of X-ray irradiation. NMR IN BIOMEDICINE 2014; 27:453-458. [PMID: 24470192 PMCID: PMC3960982 DOI: 10.1002/nbm.3081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 01/02/2014] [Accepted: 01/03/2014] [Indexed: 06/03/2023]
Abstract
The in vivo quantification of extracellular pH (pHe ) in tumours may provide a useful biomarker for tumour cell metabolism. In this study, we assessed the viability of continuous-wave electron paramagnetic resonance (CW-EPR) spectroscopy with a pH-sensitive nitroxide for the measurement of extracellular tumour pH in a mouse model. CW-EPR spectroscopy (750 MHz) of C3H HeJ mice hind leg squamous cell tumour was performed after intravenous tail vein injection of pH-sensitive nitroxide (R-SG, 2-(4-((2-(4-amino-4-carboxybutanamido)-3-(carboxymethylamino)-3-oxoproylthio)methyl)phenyl)-4-pyrrolidino-2,5,5-triethyl-2,5-dihydro-1Н-imidazol-1-oxyl) during stages of normal tumour growth and in response to a single 10-Gy dose of X-ray irradiation. An inverse relationship was observed between tumour volume and pHe value, whereby, during normal tumour growth, a constant reduction in pHe was observed. This relationship was disrupted by X-ray irradiation and, from 2-3 days post-exposure, a transitory increase in pHe was observed. In this study, we demonstrated the viability of CW-EPR spectroscopy using R-SG nitroxide to obtain high-sensitivity pH measurements in a mouse tumour model with an accuracy of <0.1 pH units. In addition, the measured changes in pHe in response to X-ray irradiation suggest that this may offer a useful method for the assessment of the physiological change in response to existing and novel cancer therapies.
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Affiliation(s)
- Jonathan Goodwin
- Department of Diagnostic Radiology, Hokkaido University Hospital, Sapporo, Japan
- Division of UltraHigh Field MRI, Iwate Medical University, Yahaba, Iwate, Japan
| | - Katsuya Yachi
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Masaki Nagane
- Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Hironobu Yasui
- Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Yusuke Miyake
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Osamu Inanami
- Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Andrey A. Bobko
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, The Ohio State University, Columbus, OH, USA
| | - Valery V. Khramtsov
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, The Ohio State University, Columbus, OH, USA
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
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Tsitovich PB, Burns PJ, McKay AM, Morrow JR. Redox-activated MRI contrast agents based on lanthanide and transition metal ions. J Inorg Biochem 2014; 133:143-54. [DOI: 10.1016/j.jinorgbio.2014.01.016] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/14/2014] [Accepted: 01/14/2014] [Indexed: 12/17/2022]
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Pilot study of Iopamidol-based quantitative pH imaging on a clinical 3T MR scanner. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2014; 27:477-85. [DOI: 10.1007/s10334-014-0433-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 12/22/2022]
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46
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Dorazio SJ, Olatunde AO, Tsitovich PB, Morrow JR. Comparison of divalent transition metal ion paraCEST MRI contrast agents. J Biol Inorg Chem 2014; 19:191-205. [PMID: 24253281 PMCID: PMC3946895 DOI: 10.1007/s00775-013-1059-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/28/2013] [Indexed: 01/06/2023]
Abstract
Transition-metal-ion-based paramagnetic chemical exchange saturation transfer (paraCEST) agents are a promising new class of compounds for magnetic resonance imaging (MRI) contrast. Members in this class of compounds include paramagnetic complexes of Fe(II), Co(II), and Ni(II). The development of the coordination chemistry for these paraCEST agents is presented with an emphasis on the choice of the azamacrocycle backbone and pendent groups with the goals of controlling the oxidation state, spin state, and stability of the complexes. Chemical exchange saturation transfer spectra and images are compared for different macrocyclic complexes containing amide or heterocyclic pendent groups. The potential of paraCEST agents that function as pH- and redox-activated MRI probes is discussed.
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Affiliation(s)
- Sarina J. Dorazio
- Department of Chemistry, University at Buffalo, Amherst, New York, 14260 USA
| | - Abiola O. Olatunde
- Department of Chemistry, University at Buffalo, Amherst, New York, 14260 USA
| | - Pavel B. Tsitovich
- Department of Chemistry, University at Buffalo, Amherst, New York, 14260 USA
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, Amherst, New York, 14260 USA
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Lim IAL, Li X, Jones CK, Farrell JAD, Vikram DS, van Zijl PCM. Quantitative magnetic susceptibility mapping without phase unwrapping using WASSR. Neuroimage 2014; 86:265-79. [PMID: 24113625 PMCID: PMC3947267 DOI: 10.1016/j.neuroimage.2013.09.072] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/03/2013] [Accepted: 09/28/2013] [Indexed: 01/06/2023] Open
Abstract
The magnetic susceptibility of tissue within and around an image voxel affects the magnetic field and thus the local frequency in that voxel. Recently, it has been shown that spatial maps of frequency can be used to quantify local susceptibility if the contributions of surrounding tissue can be deconvolved. Currently, such quantitative susceptibility mapping (QSM) methods employ gradient recalled echo (GRE) imaging to measure spatial differences in the signal phase evolution as a function of echo time, from which frequencies can be deduced. Analysis of these phase images, however, is complicated by phase wraps, despite the availability and usage of various phase unwrapping algorithms. In addition, lengthy high-resolution GRE scanning often heats the magnet bore, causing the magnetic field to drift over several Hertz, which is on the order of the frequency differences between tissues. Here, we explore the feasibility of applying the WAter Saturation Shift Referencing (WASSR) method for 3D whole brain susceptibility imaging. WASSR uses direct saturation of water protons as a function of frequency irradiation offset to generate frequency maps without phase wraps, which can be combined with any image or spectroscopy acquisition. By utilizing a series of fast short-echo-time direct saturation images with multiple radiofrequency offsets, a frequency correction for field drift can be applied based on the individual image phases. Regions of interest were delineated with an automated atlas-based method, and the average magnetic susceptibilities calculated from frequency maps obtained from WASSR correlated well with those from the phase-based multi-echo GRE approach at 3T.
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Affiliation(s)
- Issel Anne L Lim
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Xu Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Craig K Jones
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Jonathan A D Farrell
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Deepti S Vikram
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
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The stereochemistry of amide side chains containing carboxyl groups influences water exchange rates in EuDOTA-tetraamide complexes. J Biol Inorg Chem 2013; 19:161-71. [PMID: 23979260 DOI: 10.1007/s00775-013-1031-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/08/2013] [Indexed: 10/26/2022]
Abstract
Many Eu(III) complexes formed with DOTA-tetraamide ligands (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have sufficiently slow water exchange kinetics to meet the slow-to-intermediate condition required to serve as chemical exchange saturation transfer (CEST) contrast agents for MRI. This class of MRI contrast agents offers an attractive platform for creating biological sensors because water exchange is exquisitely sensitive to subtle ligand stereochemistry and electronic effects. Introduction of carboxyl groups or carboxyl ethyl ester groups on the amide substituents has been shown to slow water exchange in these complexes, but less is known about the orientation or position of these side-chain groups relative to the inner-sphere Eu(III)-bound water molecule. In this study, a series of Eu(III) complexes having one or more carboxyl groups or carboxyl esters at the δ-position of the pendant amide side chains were prepared. Initial attempts to prepare optically pure EuDOTA-[(S)-Asp]4 resulted in a chemically pure ligand consisting of a mixture of stereochemical isomers. This was traced to racemization of (S)-aspartate diethyl ester during the synthetic procedure. Nevertheless, NMR studies of the Eu(III) complexes of this mixture revealed that each isomer had a different water exchange rate, differing by a factor of 2 or more. A second controlled synthesis and CEST study of EuDOTA-[(S)-Asp]4 and cis-EuDOTA-[(S)-Asp]2[(R)-Asp]2 confirmed that the water exchange rates in these diastereomeric complexes are controlled by the axial versus equatorial orientation of the carboxyl groups on the amide side chains. These observations provide new insights toward the development of even more slowly water exchanging systems which will be necessary for practical in vivo applications.
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Melkus G, Grabau M, Karampinos DC, Majumdar S. Ex vivo porcine model to measure pH dependence of chemical exchange saturation transfer effect of glycosaminoglycan in the intervertebral disc. Magn Reson Med 2013; 71:1743-9. [PMID: 23818244 DOI: 10.1002/mrm.24838] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/15/2013] [Accepted: 05/15/2013] [Indexed: 11/07/2022]
Abstract
PURPOSE Studies have linked low pH and loss of glycosaminoglycan (GAG) in the intervertebral discs (IVDs) of patients with discogenic back pain. The purpose of this study is to determine whether the chemical exchange saturation transfer (CEST) effect of GAG (gagCEST) is pH dependent and whether it can be used to detect pH changes in IVD specimens. Iopromide, a Food and Drug Administration approved agent for CT/X-Ray, was also evaluated as a pH-sensitive CEST probe to explore the agents' potential to measure IVD pH. METHODS The pH dependency of the CEST effect of chondroitin sulfate (containing GAG) and Iopromide phantoms was investigated at 7 T. Z-spectra from porcine IVD specimens were acquired before and after manipulating the pH with sodium lactate. Iopromide was injected into the specimens and the calibration curve was used to determine the pH status. RESULTS Chondroitin sulfate showed a non-linear dependence of gagCEST effect with pH and gagCEST signal differences were detected in the specimens. The CEST effect of Iopromide resulted in a sigmoidal relation with pH and was used to measure pH. CONCLUSION gagCEST is sensitive to pH and enables investigation of the IVD pH status. Iopromide CEST is independent of the local GAG concentration and has the potential for measuring pH in the IVD.
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Affiliation(s)
- Gerd Melkus
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
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Randtke EA, Chen LQ, Corrales LR, Pagel MD. The Hanes-Woolf linear QUESP method improves the measurements of fast chemical exchange rates with CEST MRI. Magn Reson Med 2013; 71:1603-12. [PMID: 23780911 DOI: 10.1002/mrm.24792] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/14/2013] [Accepted: 04/11/2013] [Indexed: 11/08/2022]
Abstract
PURPOSE Contrast agents for chemical exchange saturation transfer MRI often require an accurate measurement of the chemical exchange rate. Many analysis methods have been reported that measure chemical exchange rates. Additional analysis methods were derived as part of this study. This report investigated the accuracy and precision of each analysis method. METHODS Chemical exchange saturation transfer spectra were simulated using the Bloch-McConnell equations modified for chemical exchange. Chemical exchange saturation transfer spectra of iopromide were obtained with a range of saturation times, saturation powers, and concentrations. These simulated and experimental results were used to estimate the chemical exchange rate using the QUESP, QUEST, Omega Plot (LB-QUESP), EH-QUESP, HW-QUESP, LB-Conc, EH-Conc, and HW-Conc methods. RESULTS Bloch fitting produced the most precise estimates of chemical exchange rates, although substantial expertise and computation time were required to achieve these results. Of the more simplistic analysis methods, the HW-QUESP method produced the most accurate and precise estimates of fast exchange rates. The QUEST and LB-QUESP methods produced the most accurate estimates of slow exchange rates, especially with samples that have short T(1w) relaxation times. CONCLUSIONS HW-QUESP is a simplistic analysis method that should be used when fast chemical exchange rates need to be estimated from chemical exchange saturation transfer MRI results.
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Affiliation(s)
- Edward A Randtke
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
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