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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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Fang T, Meng N, Feng P, Huang Z, Li Z, Fu F, Yuan J, Yang Y, Liu H, Roberts N, Wang M. A Comparative Study of Amide Proton Transfer Weighted Imaging and Intravoxel Incoherent Motion MRI Techniques Versus (18) F-FDG PET to Distinguish Solitary Pulmonary Lesions and Their Subtypes. J Magn Reson Imaging 2021; 55:1376-1390. [PMID: 34723413 DOI: 10.1002/jmri.27977] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Amide proton transfer weighted imaging (APTw), intravoxel incoherent motion (IVIM), and positron emission tomography (PET) imaging all have the potential to characterize solitary pulmonary lesions (SPLs). PURPOSE To compare APTw and IVIM with PET imaging for distinguishing between benign and malignant SPLs and their subtypes. STUDY TYPE Prospective. POPULATION Ninety-five patients, 78 with malignant SPLs (including 48 with adenocarcinoma [AC] and 17 with squamous cell carcinoma [SCC]), and 17 with benign SPLs. FIELD STRENGTH/SEQUENCE Fast spin-echo (FSE) T2WI, FSE APTw and echo-planar imaging IVIM, MR-base attenuation correction (MRAC), and PET imaging on a 3-T whole-body PET/MR system. ASSESSMENT The magnetization transfer ratio asymmetry (MTRasym) at 3.5 ppm, diffusion coefficient (D), pseudo diffusion coefficient (D*), perfusion fraction (f), and the maximum standardized uptake value (SUVmax) were analyzed. STATISTICAL TESTS Individual sample t-test, Delong test, Pearson's correlation analysis, and area under the receiver operating characteristic curve (AUC). P < 0.05 indicated statistical significance. RESULTS The MTRasym and SUVmax were significantly higher, and D was significantly lower in the malignant group (3.3 ± 2.6 [%], 7.8 ± 5, and 1.2 ± 0.3 [×10-3 mm2 /second]) compared to the benign group (-0.3 ± 1.6 [%], 3.1 ± 3.8, and 1.6 ± 0.3 [×10-3 mm2 /second]). The MTRasym and D were significantly lower, and SUVmax was significantly higher in the SCC group (0.8 ± 1.0 [%], 1.0 ± 0.2 [×10-3 mm2 /second] than in the AC group (4.1 ± 2.6 [%], 1.3 ± 0.3 [×10-3 mm2 /second], 6.7 ± 4.6). Besides, the combination (AUC = 0.964) of these three methods showed higher diagnostic efficacy than any individual method (AUC = 0.917, 0.851, 0.82, respectively) in identifying malignant and benign SPLs. However, APTw showed better diagnostic efficacy than the combination of three methods or PET imaging alone in distinguishing SCC and AC groups (AUC = 0.934, 0.781, 0.725, respectively). DATA CONCLUSION APTw, IVIM, and PET imaging are all effective methods to distinguish benign and malignant SPLs and their subtypes. APTw is potentially more capable than PET imaging of distinguishing lung SCC from AC. LEVEL OF EVIDENCE 2 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Ting Fang
- Department of Medical Imaging, Zhengzhou University People's Hospital, Zhengzhou, China.,Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China
| | - Nan Meng
- Department of Medical Imaging, Zhengzhou University People's Hospital, Zhengzhou, China.,Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China
| | - Pengyang Feng
- Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China.,Department of Medical Imaging, Henan University People's Hospital, Zhengzhou, China
| | - Zhun Huang
- Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China.,Department of Medical Imaging, Henan University People's Hospital, Zhengzhou, China
| | - Ziqiang Li
- Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China.,Department of Medical Imaging, Xinxiang Medical University, Xinxiang, China
| | - Fangfang Fu
- Department of Radiology, Henan Provincial People's Hospital, Zhengzhou, China
| | - Jianmin Yuan
- Central Research Institute, UIH Group, Shanghai, China
| | - Yang Yang
- Beijing United Imaging Research Institute of Intelligent Imaging, UIH Group, Beijing, China
| | - Hui Liu
- UIH America, Inc, Houston, Texas, USA
| | - Neil Roberts
- Clinical Research Imaging Centre, School of Clinical Sciences and Community Health, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, UK
| | - Meiyun Wang
- Department of Medical Imaging, Zhengzhou University People's Hospital, Zhengzhou, China.,Department of Medical Imaging, Henan University People's Hospital, Zhengzhou, China.,Department of Medical Imaging, Xinxiang Medical University, Xinxiang, China
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Gao T, Zou C, Li Y, Jiang Z, Tang X, Song X. A Brief History and Future Prospects of CEST MRI in Clinical Non-Brain Tumor Imaging. Int J Mol Sci 2021; 22:11559. [PMID: 34768990 PMCID: PMC8584005 DOI: 10.3390/ijms222111559] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/12/2021] [Accepted: 10/23/2021] [Indexed: 02/08/2023] Open
Abstract
Chemical exchange saturation transfer (CEST) MRI is a promising molecular imaging tool which allows the specific detection of metabolites that contain exchangeable amide, amine, and hydroxyl protons. Decades of development have progressed CEST imaging from an initial concept to a clinical imaging tool that is used to assess tumor metabolism. The first translation efforts involved brain imaging, but this has now progressed to imaging other body tissues. In this review, we summarize studies using CEST MRI to image a range of tumor types, including breast cancer, pelvic tumors, digestive tumors, and lung cancer. Approximately two thirds of the published studies involved breast or pelvic tumors which are sites that are less affected by body motion. Most studies conclude that CEST shows good potential for the differentiation of malignant from benign lesions with a number of reports now extending to compare different histological classifications along with the effects of anti-cancer treatments. Despite CEST being a unique 'label-free' approach with a higher sensitivity than MR spectroscopy, there are still some obstacles for implementing its clinical use. Future research is now focused on overcoming these challenges. Vigorous ongoing development and further clinical trials are expected to see CEST technology become more widely implemented as a mainstream imaging technology.
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Affiliation(s)
- Tianxin Gao
- School of Life Science, Institute of Engineering Medicine, Beijing Institute of Technology, Beijing 100081, China; (T.G.); (C.Z.); (Z.J.)
| | - Chuyue Zou
- School of Life Science, Institute of Engineering Medicine, Beijing Institute of Technology, Beijing 100081, China; (T.G.); (C.Z.); (Z.J.)
| | - Yifan Li
- Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing 100084, China;
| | - Zhenqi Jiang
- School of Life Science, Institute of Engineering Medicine, Beijing Institute of Technology, Beijing 100081, China; (T.G.); (C.Z.); (Z.J.)
| | - Xiaoying Tang
- School of Life Science, Institute of Engineering Medicine, Beijing Institute of Technology, Beijing 100081, China; (T.G.); (C.Z.); (Z.J.)
| | - Xiaolei Song
- Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing 100084, China;
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