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Song I, Thompson EW, Verma A, MacLean MT, Duda J, Elahi A, Tran R, Raghupathy P, Swago S, Hazim M, Bhattaru A, Schneider C, Vujkovic M, Torigian DA, Kahn CE, Gee JC, Borthakur A, Kripke CM, Carson CC, Carr R, Jehangir Q, Ko YA, Litt H, Rosen M, Mankoff DA, Schnall MD, Shou H, Chirinos J, Damrauer SM, Serper M, Chen J, Rader DJ, Witschey WRT, Sagreiya H. Clinical correlates of CT imaging-derived phenotypes among lean and overweight patients with hepatic steatosis. Sci Rep 2024; 14:53. [PMID: 38167550 PMCID: PMC10761858 DOI: 10.1038/s41598-023-49470-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
The objective of this study is to define CT imaging derived phenotypes for patients with hepatic steatosis, a common metabolic liver condition, and determine its association with patient data from a medical biobank. There is a need to further characterize hepatic steatosis in lean patients, as its epidemiology may differ from that in overweight patients. A deep learning method determined the spleen-hepatic attenuation difference (SHAD) in Hounsfield Units (HU) on abdominal CT scans as a quantitative measure of hepatic steatosis. The patient cohort was stratified by BMI with a threshold of 25 kg/m2 and hepatic steatosis with threshold SHAD ≥ - 1 HU or liver mean attenuation ≤ 40 HU. Patient characteristics, diagnoses, and laboratory results representing metabolism and liver function were investigated. A phenome-wide association study (PheWAS) was performed for the statistical interaction between SHAD and the binary characteristic LEAN. The cohort contained 8914 patients-lean patients with (N = 278, 3.1%) and without (N = 1867, 20.9%) steatosis, and overweight patients with (N = 1863, 20.9%) and without (N = 4906, 55.0%) steatosis. Among all lean patients, those with steatosis had increased rates of cardiovascular disease (41.7 vs 27.8%), hypertension (86.7 vs 49.8%), and type 2 diabetes mellitus (29.1 vs 15.7%) (all p < 0.0001). Ten phenotypes were significant in the PheWAS, including chronic kidney disease, renal failure, and cardiovascular disease. Hepatic steatosis was found to be associated with cardiovascular, kidney, and metabolic conditions, separate from overweight BMI.
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Affiliation(s)
- Isabel Song
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Elizabeth W Thompson
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Anurag Verma
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew T MacLean
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeffrey Duda
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Ameena Elahi
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Richard Tran
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Pavan Raghupathy
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Sophia Swago
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Mohamad Hazim
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Abhijit Bhattaru
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Carolin Schneider
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marijana Vujkovic
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Drew A Torigian
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Charles E Kahn
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - James C Gee
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Arijitt Borthakur
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Colleen M Kripke
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher C Carson
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rotonya Carr
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Medicine, School of Medicine, University of Washington, Seattle, WA, USA
| | - Qasim Jehangir
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-An Ko
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Harold Litt
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Mark Rosen
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - David A Mankoff
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Mitchell D Schnall
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Haochang Shou
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Julio Chirinos
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Scott M Damrauer
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marina Serper
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jinbo Chen
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel J Rader
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Walter R T Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Hersh Sagreiya
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA, 19104, USA.
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Bustin A, Witschey WRT, van Heeswijk RB, Cochet H, Stuber M. Magnetic resonance myocardial T1ρ mapping : Technical overview, challenges, emerging developments, and clinical applications. J Cardiovasc Magn Reson 2023; 25:34. [PMID: 37331930 DOI: 10.1186/s12968-023-00940-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 05/15/2023] [Indexed: 06/20/2023] Open
Abstract
The potential of cardiac magnetic resonance to improve cardiovascular care and patient management is considerable. Myocardial T1-rho (T1ρ) mapping, in particular, has emerged as a promising biomarker for quantifying myocardial injuries without exogenous contrast agents. Its potential as a contrast-agent-free ("needle-free") and cost-effective diagnostic marker promises high impact both in terms of clinical outcomes and patient comfort. However, myocardial T1ρ mapping is still at a nascent stage of development and the evidence supporting its diagnostic performance and clinical effectiveness is scant, though likely to change with technological improvements. The present review aims at providing a primer on the essentials of myocardial T1ρ mapping, and to describe the current range of clinical applications of the technique to detect and quantify myocardial injuries. We also delineate the important limitations and challenges for clinical deployment, including the urgent need for standardization, the evaluation of bias, and the critical importance of clinical testing. We conclude by outlining technical developments to be expected in the future. If needle-free myocardial T1ρ mapping is shown to improve patient diagnosis and prognosis, and can be effectively integrated in cardiovascular practice, it will fulfill its potential as an essential component of a cardiac magnetic resonance examination.
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Affiliation(s)
- Aurelien Bustin
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Université de Bordeaux, INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, Avenue du Haut Lévêque, 33604, Pessac, France.
- Department of Cardiovascular Imaging, Hôpital Cardiologique du Haut-Lévêque, CHU de Bordeaux, Avenue de Magellan, 33604, Pessac, France.
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
| | | | - Ruud B van Heeswijk
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Hubert Cochet
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Université de Bordeaux, INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, Avenue du Haut Lévêque, 33604, Pessac, France
- Department of Cardiovascular Imaging, Hôpital Cardiologique du Haut-Lévêque, CHU de Bordeaux, Avenue de Magellan, 33604, Pessac, France
| | - Matthias Stuber
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Université de Bordeaux, INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, Avenue du Haut Lévêque, 33604, Pessac, France
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
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Vallabhaneni S, Wang Y, Zhang Y, Smith A, Zou W, Feigenberg S, Plastaras J, Freedman G, Witschey WRT, Ky B, Han Y. Cardiovascular Magnetic Resonance in Early Detection of Radiation Associated Cardiotoxicity With Chest Radiation. Front Cardiovasc Med 2022; 9:867479. [PMID: 35711358 PMCID: PMC9192956 DOI: 10.3389/fcvm.2022.867479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/14/2022] [Indexed: 11/15/2022] Open
Abstract
Background Chest radiation therapy (RT) is known to be associated with cardiotoxicity. However, the changes in myocardial tissue characterization with radiation-induced cardiotoxicity are not well-understood. Objectives This study sought to assess the changes in left ventricular function and tissue characterization using cardiovascular magnetic resonance (CMR) in patients receiving RT. Materials and Methods Between June 2015 and July 2018, we enrolled patients with breast, lung cancer, or lymphoma with plan to receive chest radiation after chemotherapy. CMR was performed using a 1.5T scanner at baseline and 6 months after RT. Myocardial volume, function, strain analysis using feature tracking, and tissue characterization including late gadolinium enhancement (LGE), T1, T2, T1ρ (rho), and extracellular volume fraction (ECV) were measured and compared using non-parametric methods. Results The final cohort consisted of 16 patients, 11 of whom completed both baseline and follow-up CMRs. Patients were matched to 10 healthy controls. At baseline prior to RT, compared to controls, patients had lower global circumferential strain (GCS) (15.3 ± 2.2% vs.18.4 ± 2.1%, p = 0.004), and elevated T2 (47.9 ± 4.8 ms vs. 45.0 ± 1.5 ms, p = 0.04) and T1ρ values (78.4 ± 5.9 vs. 66.9 ± 4.6 ms, p < 0.001). Two patients had LGE. There was no significant difference in the average T1 values or ECV. There was a trend toward lower LV ejection fraction and global longitudinal strain (GLS). At 6-month follow-up after RT, there were no significant changes in all the CMR parameters. Conclusion At 6-month following chest radiation therapy, there was no change in LV and RV EF, LV and RV GLS, LV GCS, and myocardial tissue characterization using LGE, T1, ECV, T2, and T1ρ in a small cohort of patients. However, the baseline T2 and T1ρ were elevated and LV GCS was reduced compared to controls indicating ongoing myocardial edema and subclinical dysfunction post-chemotherapy.
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Affiliation(s)
- Srilakshmi Vallabhaneni
- Cardiovascular Division, Department of Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States,Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Yue Wang
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States,Department of Cardiology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying Zhang
- Department of Cardiology, People’s Liberation Army (PLA) General Hospital, Beijing, China
| | - Amanda Smith
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Wei Zou
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Steven Feigenberg
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - John Plastaras
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Gary Freedman
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Walter R. T. Witschey
- Department of Radiology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Bonnie Ky
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States
| | - Yuchi Han
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, United States,Cardiovascular Division, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States,*Correspondence: Yuchi Han,
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Liu C, Witschey WRT, Santangeli P, Han Y. Spontaneous intramyocardial haemorrhage in a patient with wild-type transthyretin cardiac amyloidosis. Eur Heart J 2021; 42:4929. [PMID: 33346807 DOI: 10.1093/eurheartj/ehaa1026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/07/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Chuanfen Liu
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA.,Department of Cardiology, Peking University People's Hospital, Beijing, China
| | - Walter R T Witschey
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
| | - Pasquale Santangeli
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
| | - Yuchi Han
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
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Thompson EW, Kamesh Iyer S, Solomon MP, Li Z, Zhang Q, Piechnik S, Werys K, Swago S, Moon BF, Rodgers ZB, Hall A, Kumar R, Reza N, Kim J, Jamil A, Desjardins B, Litt H, Owens A, Witschey WRT, Han Y. Endogenous T1ρ cardiovascular magnetic resonance in hypertrophic cardiomyopathy. J Cardiovasc Magn Reson 2021; 23:120. [PMID: 34689798 PMCID: PMC8543937 DOI: 10.1186/s12968-021-00813-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/13/2021] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is characterized by increased left ventricular wall thickness, cardiomyocyte hypertrophy, and fibrosis. Adverse cardiac risk characterization has been performed using late gadolinium enhancement (LGE), native T1, and extracellular volume (ECV). Relaxation time constants are affected by background field inhomogeneity. T1ρ utilizes a spin-lock pulse to decrease the effect of unwanted relaxation. The objective of this study was to study T1ρ as compared to T1, ECV, and LGE in HCM patients. METHODS HCM patients were recruited as part of the Novel Markers of Prognosis in Hypertrophic Cardiomyopathy study, and healthy controls were matched for comparison. In addition to cardiac functional imaging, subjects underwent T1 and T1ρ cardiovascular magnetic resonance imaging at short-axis positions at 1.5T. Subjects received gadolinium and underwent LGE imaging 15-20 min after injection covering the entire heart. Corresponding basal and mid short axis LGE slices were selected for comparison with T1 and T1ρ. Full-width half-maximum thresholding was used to determine the percent enhancement area in each LGE-positive slice by LGE, T1, and T1ρ. Two clinicians independently reviewed LGE images for presence or absence of enhancement. If in agreement, the image was labeled positive (LGE + +) or negative (LGE --); otherwise, the image was labeled equivocal (LGE + -). RESULTS In 40 HCM patients and 10 controls, T1 percent enhancement area (Spearman's rho = 0.61, p < 1e-5) and T1ρ percent enhancement area (Spearman's rho = 0.48, p < 0.001e-3) correlated with LGE percent enhancement area. T1 and T1ρ percent enhancement areas were also correlated (Spearman's rho = 0.28, p = 0.047). For both T1 and T1ρ, HCM patients demonstrated significantly longer relaxation times compared to controls in each LGE category (p < 0.001 for all). HCM patients also showed significantly higher ECV compared to controls in each LGE category (p < 0.01 for all), and LGE -- slices had lower ECV than LGE + + (p = 0.01). CONCLUSIONS Hyperenhancement areas as measured by T1ρ and LGE are moderately correlated. T1, T1ρ, and ECV were elevated in HCM patients compared to controls, irrespective of the presence of LGE. These findings warrant additional studies to investigate the prognostic utility of T1ρ imaging in the evaluation of HCM patients.
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Affiliation(s)
- Elizabeth W Thompson
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Michael P Solomon
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Zhaohuan Li
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Ultrasound in Cardiac Electrophysiology and Biomechanics Key Laboratory of Sichuan Province, Cardiovascular Ultrasound and Non-Invasive Cardiology Department, Affiliated Hospital of University of Electronic Science and Technology of China, Sichuan Academy of Medical Sciences, Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Qiang Zhang
- Oxford Center for Clinical Magnetic Resonance Research, Oxford BRC NIHR, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Stefan Piechnik
- Oxford Center for Clinical Magnetic Resonance Research, Oxford BRC NIHR, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Konrad Werys
- Circle Cardiovascular Imaging Inc., Calgary, AB, Canada
| | - Sophia Swago
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Brianna F Moon
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Zachary B Rodgers
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Anya Hall
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Rishabh Kumar
- Department of Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Nosheen Reza
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jessica Kim
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alisha Jamil
- Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Benoit Desjardins
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Harold Litt
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Anjali Owens
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Yuchi Han
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Perelman School of Medicine, University of Pennsylvania, 11-135, South Pavilion, 3400 Civic Center Blvd., Philadelphia, PA, 19104, USA.
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Contijoch F, Han Y, Kamesh Iyer S, Kellman P, Gualtieri G, Elliott MA, Berisha S, Gorman JH, Gorman RC, Pilla JJ, Witschey WRT. Closed-loop control of k-space sampling via physiologic feedback for cine MRI. PLoS One 2020; 15:e0244286. [PMID: 33373391 PMCID: PMC7771662 DOI: 10.1371/journal.pone.0244286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/08/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Segmented cine cardiac MRI combines data from multiple heartbeats to achieve high spatiotemporal resolution cardiac images, yet predefined k-space segmentation trajectories can lead to suboptimal k-space sampling. In this work, we developed and evaluated an autonomous and closed-loop control system for radial k-space sampling (ARKS) to increase sampling uniformity. METHODS The closed-loop system autonomously selects radial k-space sampling trajectory during live segmented cine MRI and attempts to optimize angular sampling uniformity by selecting views in regions of k-space that were not previously well-sampled. Sampling uniformity and the ability to detect cardiac phase in vivo was assessed using ECG data acquired from 10 normal subjects in an MRI scanner. The approach was then implemented with a fast gradient echo sequence on a whole-body clinical MRI scanner and imaging was performed in 4 healthy volunteers. The closed-loop k-space trajectory was compared to random, uniformly distributed and golden angle view trajectories via measurement of k-space uniformity and the point spread function. Lastly, an arrhythmic dataset was used to evaluate a potential application of the approach. RESULTS The autonomous trajectory increased k-space sampling uniformity by 15±7%, main lobe point spread function (PSF) signal intensity by 6±4%, and reduced ringing relative to golden angle sampling. When implemented, the autonomous pulse sequence prescribed radial view angles faster than the scan TR (0.98 ± 0.01 ms, maximum = 1.38 ms) and increased k-space sampling mean uniformity by 10±11%, decreased uniformity variability by 44±12%, and increased PSF signal ratio by 6±6% relative to golden angle sampling. CONCLUSION The closed-loop approach enables near-uniform radial sampling in a segmented acquisition approach which was higher than predetermined golden-angle radial sampling. This can be utilized to increase the sampling or decrease the temporal footprint of an acquisition and the closed-loop framework has the potential to be applied to patients with complex heart rhythms.
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Affiliation(s)
- Francisco Contijoch
- Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, CA, United States of America
- Department of Radiology, School of Medicine, University of California, San Diego, CA, United States of America
| | - Yuchi Han
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Srikant Kamesh Iyer
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Peter Kellman
- National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | | | - Mark A. Elliott
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Sebastian Berisha
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Joseph H. Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Robert C. Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - James J. Pilla
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Walter R. T. Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
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7
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Hwuang E, Vidorreta M, Schwartz N, Moon BF, Kochar K, Tisdall MD, Detre JA, Witschey WRT. Assessment of uterine artery geometry and hemodynamics in human pregnancy with 4d flow mri and its correlation with doppler ultrasound. J Magn Reson Imaging 2018; 49:59-68. [PMID: 30390347 DOI: 10.1002/jmri.26229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/31/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Uterine artery (UtA) hemodynamics might be used to predict risk of hypertensive pregnancy disorders, including preeclampsia and intrauterine growth restriction. PURPOSE OR HYPOTHESIS To determine the feasibility of 4D flow MRI in pregnant subjects by characterizing UtA anatomy, computing UtA flow, and comparing UtA velocity, and pulsatility and resistivity indices (PI, RI) with transabdominal Doppler ultrasound (US). STUDY TYPE Prospective cross-sectional study from June 6, 2016, to May 2, 2018. POPULATION OR SUBJECTS OR PHANTOM OR SPECIMEN OR ANIMAL MODEL Forty-one singleton pregnant subjects (age [range] = 27.0 ± 5.9 [18-41] years) in their second or third trimester. We additionally scanned three subjects who had prepregnancy diabetes or chronic hypertension. FIELD STRENGTH/SEQUENCE The subjects underwent UtA and placenta MRI using noncontrast angiography and 4D flow at 1.5T. ASSESSMENT UtA anatomy was described based on 4D flow-derived noncontrast angiography, while UtA flow properties were characterized by net flow, systolic/mean/diastolic velocity, PI and RI through examination of 4D flow data. PI and RI are standard hemodynamic parameters routinely reported on Doppler US. STATISTICAL TESTS Spearman's rank correlation, Wilcoxon signed rank tests, and Bland-Altman plots were used to preliminarily investigate the relationships between flow parameters, gestational age, and Doppler US. or RESULTS: 4D flow MRI and UtA flow quantification was feasible in all subjects. There was considerable heterogeneity in UtA geometry in each subject between left and right UtAs and between subjects. Mean 4D flow-based parameters were: mean bilateral flow rate = 605.6 ± 220.5 mL/min, PI = 0.72 ± 0.2, and RI = 0.47 ± 0.1. Bilateral flow did not change with gestational age. We found that MRI differed from US in terms of lower PI (mean difference -0.1) and RI (mean difference < -0.1) with Wilcoxon signed rank test P = 0.05 and P = 0.13, respectively. DATA CONCLUSION 4D flow MRI is a feasible approach for describing UtA anatomy and flow in pregnant subjects. LEVEL OF EVIDENCE Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:59-68.
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Affiliation(s)
- Eileen Hwuang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Marta Vidorreta
- Siemens Healthineers, Tarrytown, New York, USA.,Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nadav Schwartz
- Department of Obstetrics and Gynecology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Brianna F Moon
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kirpal Kochar
- Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Matthew Dylan Tisdall
- Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - John A Detre
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Walter R T Witschey
- Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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8
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Hsu JC, Naha PC, Lau KC, Chhour P, Hastings R, Moon BF, Stein JM, Witschey WRT, McDonald ES, Maidment ADA, Cormode DP. An all-in-one nanoparticle (AION) contrast agent for breast cancer screening with DEM-CT-MRI-NIRF imaging. Nanoscale 2018; 10:17236-17248. [PMID: 30191237 PMCID: PMC6148383 DOI: 10.1039/c8nr03741h] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Conventional X-ray mammography has low diagnostic sensitivity for women with dense breasts. As a result, alternative contrast-enhanced screening tools such as dual energy mammography (DEM), computed tomography (CT), magnetic resonance imaging (MRI), and near-infrared fluorescence (NIRF) imaging are being used or investigated for these women. However, currently available contrast agents are non-ideal, have safety issues, and each imaging technique requires a different contrast agent. We therefore sought to develop a multimodal contrast agent that is functional for each breast imaging modality to simplify the diagnosis process and address the issues of existing contrast agents. Herein, we present a novel "all-in-one" nanoparticle (AION) multimodal imaging probe that has potent DEM, CT, MRI, and NIRF contrast properties and improved biocompatibility. AION were formed by co-encapsulation of a near-infrared fluorophore (DiR), silver sulfide nanoparticles (Ag2S-NP), and iron oxide nanoparticles (IO-NP) in PEGylated micelles. AION showed negligible cytotoxicity, which was in agreement with its minimal silver ion release profiles. AION generated strong contrast with all imaging modalities as demonstrated in phantom imaging. AION allowed in vivo tumor imaging as evidenced by the increase in contrast after injection. This study indicates the potential of AION as an effective multimodal contrast agent for breast cancer diagnosis with a range of imaging methods.
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Affiliation(s)
- Jessica C Hsu
- Department of Radiology, University of Pennsylvania, 3400 Spruce St, 1 Silverstein, Philadelphia, PA 19104, USA.
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9
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Wang J, Zhao H, Wang Y, Herrmann HC, Witschey WRT, Han Y. Native T1 and T2 mapping by cardiovascular magnetic resonance imaging in pressure overloaded left and right heart diseases. J Thorac Dis 2018; 10:2968-2975. [PMID: 29997963 DOI: 10.21037/jtd.2018.04.141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Background Pulmonary arterial hypertension (PAH) and severe aortic valve stenosis (AS) are diseases characterized by increased afterload of the right and left heart, respectively. Our study aims to investigate the differences of myocardial tissue characteristics in the pressure overloaded left and right hearts, especially in the shared interventricular septum, as detected by native T1 and T2 relaxation times. Methods Eighteen patients with PAH and 19 patients with severe AS in addition to 5 healthy volunteers underwent 1.5-T CMR examination with native T1 and T2 mapping. Mean T1 and T2 value were measured at the right ventricular (RV) free wall, superior RV insertion, inferior RV insertion, interventricular septum and left ventricular (LV) lateral wall. Results Compared with controls and AS group, T1 was significantly elevated in the RV insertion in PAH group (P=0.015), while no statistically significant differences were seen in other segments among the three groups. There was an increase of T2 in the RV insertion in AS and PAH groups (P=0.01). Significant T2 elevation was also observed in the RV free wall of PAH group, and the LV lateral wall of AS group compared with the control group. RV insertion T2 was significantly correlated with RV end-diastolic volume index (r=0.608, P=0.016) and RV mass index (r=0.57, P=0.026) in the PAH group. LV lateral wall T2 and RV insertion T2 were significantly correlated with aortic valve mean gradients in the AS group (r=0.56, P=0.02; r=0.58, P=0.01, respectively). Conclusions In pressure overload diseases, both T1 and T2 values increase in the myocardium. The alterations seen in the RV insertion sites in the septum was more pronounced with RV pressure overload. T2 values also correlated with structural and functional remodeling in both diseases. Combining T1 and T2 mapping may help to better characterize the alternation of myocardial composition in pressure overloaded heart diseases.
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Affiliation(s)
- Jing Wang
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Cardiology, PLA General Hospital, Beijing 100853, China
| | - Hang Zhao
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Cardiology, Shanghai Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200127, China
| | - Yue Wang
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Cardiology, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200001, China
| | - Howard C Herrmann
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Walter R T Witschey
- Department of Radiology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA
| | - Yuchi Han
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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10
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Rodell CB, Lee ME, Wang H, Takebayashi S, Takayama T, Kawamura T, Arkles JS, Dusaj NN, Dorsey SM, Witschey WRT, Pilla JJ, Gorman JH, Wenk JF, Burdick JA, Gorman RC. Injectable Shear-Thinning Hydrogels for Minimally Invasive Delivery to Infarcted Myocardium to Limit Left Ventricular Remodeling. Circ Cardiovasc Interv 2017; 9:CIRCINTERVENTIONS.116.004058. [PMID: 27729419 DOI: 10.1161/circinterventions.116.004058] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 09/07/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Injectable, acellular biomaterials hold promise to limit left ventricular remodeling and heart failure precipitated by infarction through bulking or stiffening the infarct region. A material with tunable properties (eg, mechanics, degradation) that can be delivered percutaneously has not yet been demonstrated. Catheter-deliverable soft hydrogels with in vivo stiffening to enhance therapeutic efficacy achieve these requirements. METHODS AND RESULTS We developed a hyaluronic acid hydrogel that uses a tandem crosslinking approach, where the first crosslinking (guest-host) enabled injection and localized retention of a soft (<1 kPa) hydrogel. A second crosslinking reaction (dual-crosslinking) stiffened the hydrogel (41.4±4.3 kPa) after injection. Posterolateral infarcts were investigated in an ovine model (n≥6 per group), with injection of saline (myocardial infarction control), guest-host hydrogels, or dual-crosslinking hydrogels. Computational (day 1), histological (1 day, 8 weeks), morphological, and functional (0, 2, and 8 weeks) outcomes were evaluated. Finite-element modeling projected myofiber stress reduction (>50%; P<0.001) with dual-crosslinking but not guest-host injection. Remodeling, assessed by infarct thickness and left ventricular volume, was mitigated by hydrogel treatment. Ejection fraction was improved, relative to myocardial infarction at 8 weeks, with dual-crosslinking (37% improvement; P=0.014) and guest-host (15% improvement; P=0.058) treatments. Percutaneous delivery via endocardial injection was investigated with fluoroscopic and echocardiographic guidance, with delivery visualized by magnetic resonance imaging. CONCLUSIONS A percutaneous delivered hydrogel system was developed, and hydrogels with increased stiffness were found to be most effective in ameliorating left ventricular remodeling and preserving function. Ultimately, engineered systems such as these have the potential to provide effective clinical options to limit remodeling in patients after infarction.
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Affiliation(s)
- Christopher B Rodell
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Madonna E Lee
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Hua Wang
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Satoshi Takebayashi
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Tetsushi Takayama
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Tomonori Kawamura
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jeffrey S Arkles
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Neville N Dusaj
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Shauna M Dorsey
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Walter R T Witschey
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - James J Pilla
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Joseph H Gorman
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jonathan F Wenk
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jason A Burdick
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington.
| | - Robert C Gorman
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington.
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11
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Stoffers RH, Madden M, Shahid M, Contijoch F, Solomon J, Pilla JJ, Gorman JH, Gorman RC, Witschey WRT. Erratum to: Assessment of myocardial injury after reperfused infarction by T1ρ cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2017; 19:42. [PMID: 28347308 PMCID: PMC5368938 DOI: 10.1186/s12968-017-0354-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Rutger H Stoffers
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Marie Madden
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Mohammed Shahid
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Francisco Contijoch
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph Solomon
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - James J Pilla
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Walter R T Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1 Silverstein 3400 Spruce Street, Philadelphia, PA, 19104, USA.
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12
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McCormick ME, Manduchi E, Witschey WRT, Gorman RC, Gorman JH, Jiang YZ, Stoeckert CJ, Barker AJ, Yoon S, Markl M, Davies PF. Spatial phenotyping of the endocardial endothelium as a function of intracardiac hemodynamic shear stress. J Biomech 2016; 50:11-19. [PMID: 27916240 DOI: 10.1016/j.jbiomech.2016.11.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/02/2016] [Indexed: 02/02/2023]
Abstract
Despite substantial evidence for the central role of hemodynamic shear stress in the functional integrity of vascular endothelial cells, hemodynamic and molecular regulation of the endocardial endothelium lining the heart chambers remains understudied. We propose that regional differences in intracardiac hemodynamics influence differential endocardial gene expression leading to phenotypic heterogeneity of this cell layer. Measurement of intracardiac hemodynamics was performed using 4-dimensional flow MRI in healthy humans (n=8) and pigs (n=5). Local wall shear stress (WSS) and oscillatory shear indices (OSI) were calculated in three distinct regions of the LV - base, mid-ventricle (midV), and apex. In both the humans and pigs, WSS values were significantly lower in the apex and midV relative to the base. Additionally, both the apex and midV had greater oscillatory shear indices (OSI) than the base. To investigate regional phenotype, endocardial endothelial cells (EEC) were isolated from an additional 8 pigs and RNA sequencing was performed. A false discovery rate of 0.10 identified 1051 differentially expressed genes between the base and apex, and 321 between base and midV. Pathway analyses revealed apical upregulation of genes associated with translation initiation. Furthermore, tissue factor pathway inhibitor (TFPI; mean 50-fold) and prostacyclin synthase (PTGIS; 5-fold), genes prominently associated with antithrombotic protection, were consistently upregulated in LV apex. These spatio-temporal WSS values in defined regions of the left ventricle link local hemodynamics to regional heterogeneity in endocardial gene expression.
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Affiliation(s)
- Margaret E McCormick
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Elisabetta Manduchi
- Institute for Biomedical Informatics and Departments of, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Robert C Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-Zhou Jiang
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christian J Stoeckert
- Institute for Biomedical Informatics and Departments of, University of Pennsylvania, Philadelphia, PA, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alex J Barker
- Departments of Radiology, Northwestern University, Chicago, IL, USA
| | - Samuel Yoon
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael Markl
- Departments of Radiology, Northwestern University, Chicago, IL, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA
| | - Peter F Davies
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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13
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Contijoch F, Iyer SK, Pilla JJ, Yushkevich P, Gorman JH, Gorman RC, Litt H, Han Y, Witschey WRT. Self-gated MRI of multiple beat morphologies in the presence of arrhythmias. Magn Reson Med 2016; 78:678-688. [PMID: 27579717 DOI: 10.1002/mrm.26381] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 07/01/2016] [Accepted: 07/22/2016] [Indexed: 01/17/2023]
Abstract
PURPOSE Develop self-gated MRI for distinct heartbeat morphologies in subjects with arrhythmias. METHODS Golden angle radial data was obtained in seven sinus and eight arrhythmias subjects. An image-based cardiac navigator was derived from single-shot images, distinct beat types were identified, and images were reconstructed for repeated morphologies. Image sharpness, contrast, and volume variation were quantified and compared with self-gated MRI. Images were scored for image quality and artifacts. Hemodynamic parameters were computed for each distinct beat morphology in bigeminy and trigeminy subjects and for sinus beats in patients with infrequent premature ventricular contractions. RESULTS Images of distinct beat types were reconstructed except for two patients with infrequent premature ventricular contractions. Image contrast and sharpness were similar to sinus self-gated images (contrast = 0.45 ± 0.13 and 0.43 ± 0.15; sharpness = 0.21 ± 0.11 and 0.20 ± 0.05). Visual scoring was highest in self-gated images (4.1 ± 0.3) compared with real-time (3.9 ± 0.4) and ECG-gated cine (3.4 ± 1.5). ECG-gated cine had less artifacts than self-gating (2.3 ± 0.7 and 2.1 ± 0.2), but was affected by misgating in two subjects. Among arrhythmia subjects, post-extrasystole/sinus (58.1 ± 8.6 mL) and interrupted sinus (61.4 ± 5.9 mL) stroke volume was higher than extrasystole (32.0 ± 16.5 mL; P < 0.02). CONCLUSION Self-gated imaging can reconstruct images during ectopy and allowed for quantification of hemodynamic function of different beat morphologies. Magn Reson Med 78:678-688, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Francisco Contijoch
- School of Medicine, University of California - San Diego, San Diego, California, USA
| | - Srikant Kamesh Iyer
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - James J Pilla
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul Yushkevich
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph H Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert C Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harold Litt
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yuchi Han
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Walter R T Witschey
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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14
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Contijoch FJ, Witschey WRT, McGarvey J, Lee ME, Gorman J, Gorman RC, Pilla JJ. Slice-by-Slice Pressure-Volume Loop Analysis Demonstrates Native Differences in Regional Cardiac Contractility and Response to Inotropic Agents. Ann Thorac Surg 2016; 102:796-802. [PMID: 27112654 DOI: 10.1016/j.athoracsur.2016.02.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 02/01/2016] [Accepted: 02/16/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND Regional changes in diastolic and systolic properties after myocardial infarction contribute to adverse left ventricular (LV) remodeling. Regional function is currently assessed using load-dependent measures such as slice ejection fraction (sEF), wall motion abnormalities, or strain imaging. However, load-independent measures of cardiac function may be useful in the study of the infarction-induced remodeling. METHODS In this study, we used a recently validated 2-dimensional (2D) real-time magnetic resonance imaging (MRI) technique to evaluate regional variations in load-independent slice-by-slice measures of systolic and diastolic function and compared the values to a load-dependent measure in 11 sheep at rest and during inotropic agent infusion. RESULTS Slice-derived ejection fraction (sEF) was greater in the apex relative to the midventricular and basal regions, and inotropic infusion increased sEF in the base more than in the apex and midventricle. Slice-derived ESPVR (sESPVR) in the apex was significantly lower than in the midventricle and the base, and inotropic infusion increased sESPVR in the apical slices more than in the midventricle. Similarly, slice-derived volume-axis intercept V0 (sV0) was higher in the base relative to the midventricle and apex. sEDPVR did not demonstrate significant regional variations, but inotropic infusion resulted in a small increase in the apex. CONCLUSIONS In conclusion, acquisition of slice-derived load-independent measures demonstrated variations that contradict those observed with load-dependent sEF. The approach may provide advanced slice-based measures of function during the LV remodeling process and aid in the development of therapies.
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Affiliation(s)
- Francisco J Contijoch
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Walter R T Witschey
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jeremy McGarvey
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Madonna E Lee
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - James J Pilla
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
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15
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McCormick ME, Manduchi E, Witschey WRT, Gorman RC, Gorman JH, Jiang YZ, Stoeckert CJ, Barker AJ, Markl M, Davies PF. Integrated Regional Cardiac Hemodynamic Imaging and RNA Sequencing Reveal Corresponding Heterogeneity of Ventricular Wall Shear Stress and Endocardial Transcriptome. J Am Heart Assoc 2016; 5:e003170. [PMID: 27091183 PMCID: PMC4859290 DOI: 10.1161/jaha.115.003170] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Background Unlike arteries, in which regionally distinct hemodynamics are associated with phenotypic heterogeneity, the relationships between endocardial endothelial cell phenotype and intraventricular flow remain largely unexplored. We investigated regional differences in left ventricular wall shear stress and their association with endocardial endothelial cell gene expression. Methods and Results Local wall shear stress was calculated from 4‐dimensional flow magnetic resonance imaging in 3 distinct regions of human (n=8) and pig (n=5) left ventricle: base, adjacent to the outflow tract; midventricle; and apex. In both species, wall shear stress values were significantly lower in the apex and midventricle relative to the base; oscillatory shear index was elevated in the apex. RNA sequencing of the endocardial endothelial cell transcriptome in pig left ventricle (n=8) at a false discovery rate ≤10% identified 1051 genes differentially expressed between the base and the apex and 327 between the base and the midventricle; no differentially expressed genes were detected at this false discovery rate between the apex and the midventricle. Enrichment analyses identified apical upregulation of genes associated with translation initiation including mammalian target of rapamycin, and eukaryotic initiation factor 2 signaling. Genes of mitochondrial dysfunction and oxidative phosphorylation were also consistently upregulated in the left ventricular apex, as were tissue factor pathway inhibitor (mean 50‐fold) and prostacyclin synthase (5‐fold)—genes prominently associated with antithrombotic protection. Conclusions We report the first spatiotemporal measurements of wall shear stress within the left ventricle and linked regional hemodynamics to heterogeneity in ventricular endothelial gene expression, most notably to translation initiation and anticoagulation properties in the left ventricular apex, in which oscillatory shear index is increased and wall shear stress is decreased.
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Affiliation(s)
- Margaret E McCormick
- Institute for Medicine and Engineering, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Elisabetta Manduchi
- Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Walter R T Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Robert C Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Joseph H Gorman
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Yi-Zhou Jiang
- Institute for Medicine and Engineering, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Christian J Stoeckert
- Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Alex J Barker
- Department of Radiology, Northwestern University, Chicago, IL
| | - Michael Markl
- Department of Radiology, Northwestern University, Chicago, IL Department of Biomedical Engineering, Northwestern University, Chicago, IL
| | - Peter F Davies
- Institute for Medicine and Engineering, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Contijoch F, Rogers K, Rears H, Shahid M, Kellman P, Gorman J, Gorman RC, Yushkevich P, Zado ES, Supple GE, Marchlinski FE, Witschey WRT, Han Y. Quantification of Left Ventricular Function With Premature Ventricular Complexes Reveals Variable Hemodynamics. Circ Arrhythm Electrophysiol 2016; 9:e003520. [PMID: 27009416 PMCID: PMC4807630 DOI: 10.1161/circep.115.003520] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 02/19/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Premature ventricular complexes (PVCs) are prevalent in the general population and are sometimes associated with reduced ventricular function. Current echocardiographic and cardiovascular magnetic resonance imaging techniques do not adequately address the effect of PVCs on left ventricular function. METHODS AND RESULTS Fifteen subjects with a history of frequent PVCs undergoing cardiovascular magnetic resonance imaging had real-time slice volume quantification performed using a 2-dimensional (2D) real-time cardiovascular magnetic resonance imaging technique. Synchronization of 2D real-time imaging with patient ECG allowed for different beats to be categorized by the loading beat RR duration and beat RR duration. For each beat type, global volumes were quantified via summation over all slices covering the entire ventricle. Different patterns of ectopy, including isolated PVCs, bigeminy, trigeminy, and interpolated PVCs, were observed. Global functional measurement of the different beat types based on timing demonstrated differences in preload, stroke volume, and ejection fraction. An average of hemodynamic function was quantified for each subject depending on the frequency of each observed beat type. CONCLUSIONS Application of real-time cardiovascular magnetic resonance imaging in patients with PVCs revealed differential contribution of PVCs to hemodynamics.
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Affiliation(s)
- Francisco Contijoch
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.).
| | - Kelly Rogers
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Hannah Rears
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Mohammed Shahid
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Peter Kellman
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Joseph Gorman
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Robert C Gorman
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Paul Yushkevich
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Erica S Zado
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Gregory E Supple
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Francis E Marchlinski
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Walter R T Witschey
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
| | - Yuchi Han
- From the Department of Bioengineering (F.C.), Cardiovascular Division, Department of Medicine (K.R., E.S.Z., G.E.S., F.E.M., Y.H.), Department of Radiology (H.R., M.S., P.Y., W.R.T.W.), and Department of Surgery (J.G., R.C.G.), University of Pennsylvania, Philadelphia; and Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (P.K.)
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Berisha S, Han J, Shahid M, Han Y, Witschey WRT. Measurement of Myocardial T1ρ with a Motion Corrected, Parametric Mapping Sequence in Humans. PLoS One 2016; 11:e0151144. [PMID: 27003184 PMCID: PMC4803208 DOI: 10.1371/journal.pone.0151144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/23/2016] [Indexed: 11/19/2022] Open
Abstract
Purpose To develop a robust T1ρ magnetic resonance imaging (MRI) sequence for assessment of myocardial disease in humans. Materials and Methods We developed a breath-held T1ρ mapping method using a single-shot, T1ρ-prepared balanced steady-state free-precession (bSSFP) sequence. The magnetization trajectory was simulated to identify sources of T1ρ error. To limit motion artifacts, an optical flow-based image registration method was used to align T1ρ images. The reproducibility and accuracy of these methods was assessed in phantoms and 10 healthy subjects. Results are shown in 1 patient with pre-ventricular contractions (PVCs), 1 patient with chronic myocardial infarction (MI) and 2 patients with hypertrophic cardiomyopathy (HCM). Results In phantoms, the mean bias was 1.0 ± 2.7 msec (100 msec phantom) and 0.9 ± 0.9 msec (60 msec phantom) at 60 bpm and 2.2 ± 3.2 msec (100 msec) and 1.4 ± 0.9 msec (60 msec) at 80 bpm. The coefficient of variation (COV) was 2.2 (100 msec) and 1.3 (60 msec) at 60 bpm and 2.6 (100 msec) and 1.4 (60 msec) at 80 bpm. Motion correction improved the alignment of T1ρ images in subjects, as determined by the increase in Dice Score Coefficient (DSC) from 0.76 to 0.88. T1ρ reproducibility was high (COV < 0.05, intra-class correlation coefficient (ICC) = 0.85–0.97). Mean myocardial T1ρ value in healthy subjects was 63.5 ± 4.6 msec. There was good correspondence between late-gadolinium enhanced (LGE) MRI and increased T1ρ relaxation times in patients. Conclusion Single-shot, motion corrected, spin echo, spin lock MRI permits 2D T1ρ mapping in a breath-hold with good accuracy and precision.
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Affiliation(s)
- Sebastian Berisha
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Joyce Han
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mohammed Shahid
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yuchi Han
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Walter R. T. Witschey
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Teraphongphom N, Chhour P, Eisenbrey JR, Naha PC, Witschey WRT, Opasanont B, Jablonowski L, Cormode DP, Wheatley MA. Nanoparticle Loaded Polymeric Microbubbles as Contrast Agents for Multimodal Imaging. Langmuir 2015; 31:11858-67. [PMID: 26446176 PMCID: PMC4818153 DOI: 10.1021/acs.langmuir.5b03473] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Ultrasound contrast agents are typically microbubbles (MB) with a gas core that is stabilized by a shell made of lipids, proteins, or polymers. The high impedance mismatch between the gas core and an aqueous environment produces strong contrast in ultrasound (US). Poly(lactic acid) (PLA) MB, previously developed in our laboratory, have been shown to be highly echogenic both in vitro and in vivo. Combining US with other imaging modalities such as fluorescence, magnetic resonance imaging (MRI), or computerized tomography (CT) could improve the accuracy of many US applications and provide more comprehensive diagnostic information. Furthermore, our MB have the capacity to house a drug in the PLA shell and create drug-loaded nanoparticles in situ when passing through an ultrasound beam. To create multimodal contrast agents, we hypothesized that the polymer shell of our PLA MB platform could accommodate additional payloads. In this study, we therefore modified our current MB by encapsulating nanoparticles including aqueous or organic quantum dots (QD), magnetic iron oxide nanoparticles (MNP), or gold nanoparticles (AuNP) to create bimodality platforms in a manner that minimally compromised the performance of each individual imaging technique.
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Affiliation(s)
- Nutte Teraphongphom
- School of Biomedical Engineering, Science and Health Systems, Drexel University , Philadelphia, Pennsylvania 19104 United States
| | - Peter Chhour
- Department of Radiology, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - John R Eisenbrey
- Department of Radiology, Thomas Jefferson University , Philadelphia, Pennsylvania 19107, United States
| | - Pratap C Naha
- Department of Radiology, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Walter R T Witschey
- Department of Radiology, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
- Department of Surgery, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Borirak Opasanont
- Chemical and Biological Engineering Department, Drexel University , Philadelphia, Pennsylvania 19104 United States
| | - Lauren Jablonowski
- School of Biomedical Engineering, Science and Health Systems, Drexel University , Philadelphia, Pennsylvania 19104 United States
| | - David P Cormode
- Department of Radiology, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Margaret A Wheatley
- School of Biomedical Engineering, Science and Health Systems, Drexel University , Philadelphia, Pennsylvania 19104 United States
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Contijoch F, Witschey WRT, Rogers K, Gorman J, Gorman RC, Ferrari V, Han Y. Impact of end-diastolic and end-systolic phase selection in the volumetric evaluation of cardiac MRI. J Magn Reson Imaging 2015; 43:585-93. [PMID: 26331591 DOI: 10.1002/jmri.25038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 08/13/2015] [Accepted: 08/17/2015] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To evaluate the impact of end-diastolic (ED) and end-systolic (ES) cardiac phase selection methods, since task force recommendations have neither provided quantitative evidence nor explored errors introduced by clinical shortcuts. MATERIALS AND METHODS Multislice, short-axis cine images were collected in 60 clinical patients on a 1.5T scanner. User-initialized active contour segmentation software quantified global left ventricular (LV) volume across all cardiac phases. Different approaches for selection of ED and ES phase were evaluated by quantification of temporal and volumetric errors. RESULTS For diastole, the mid-ventricular maximum slice volume coincided with maximum global volume in 82.1% of patients with ejection fraction (EF) ≥55% (P = 0.66) and 71.9% of patients with EF <55% (P = 0.28) and is an accurate approximation of maximum global volume while the first and last phases in a retrospectively electrocardiogram (ECG)-gated acquisition introduced differences in cardiac phase selection (P < 0.001) which led to large errors in measured volume in some patients (12.7 and 10.1 mL, respectively). For systole, post-systolic shortening occurred in a significantly higher number of patients with EF <55% (18.9%) compared to 3.6% of patients with EF ≥55% (P = 0.001), which differentially impacted end-systolic volume estimation. CONCLUSION For end-diastolic phase selection, our results indicated that the use of the mid-ventricular slice volume maximum provided accurate volume estimates, while selection of the first or last cardiac phase introduced differences in measured volume. For end-systolic phase, patients with EF <55% had a higher prevalence of post-systolic shortening, which suggests aortic valve closure should be used to estimate end-systolic volume.
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Affiliation(s)
- Francisco Contijoch
- Department of Bioengineering, University of Pennsylvania, PA, Pennsylvania, USA
| | - Walter R T Witschey
- Hospital of the University of Pennsylvania, Department of Radiology, Philadelphia, Pennsylvania, USA
| | - Kelly Rogers
- Department of Bioengineering, University of Pennsylvania, PA, Pennsylvania, USA
| | - Joseph Gorman
- Hospital of the University of Pennsylvania, Department of Surgery, Philadelphia, Pennsylvania, USA
| | - Robert C Gorman
- Hospital of the University of Pennsylvania, Department of Surgery, Philadelphia, Pennsylvania, USA
| | - Victor Ferrari
- Hospital of the University of Pennsylvania, Cardiovascular Division, Philadelphia, Pennsylvania, USA
| | - Yuchi Han
- Hospital of the University of Pennsylvania, Cardiovascular Division, Philadelphia, Pennsylvania, USA
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Contijoch F, Witschey WRT, Rogers K, Rears H, Hansen M, Yushkevich P, Gorman J, Gorman RC, Han Y. User-initialized active contour segmentation and golden-angle real-time cardiovascular magnetic resonance enable accurate assessment of LV function in patients with sinus rhythm and arrhythmias. J Cardiovasc Magn Reson 2015; 17:37. [PMID: 25994390 PMCID: PMC4440288 DOI: 10.1186/s12968-015-0146-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/08/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Data obtained during arrhythmia is retained in real-time cardiovascular magnetic resonance (rt-CMR), but there is limited and inconsistent evidence to show that rt-CMR can accurately assess beat-to-beat variation in left ventricular (LV) function or during an arrhythmia. METHODS Multi-slice, short axis cine and real-time golden-angle radial CMR data was collected in 22 clinical patients (18 in sinus rhythm and 4 patients with arrhythmia). A user-initialized active contour segmentation (ACS) software was validated via comparison to manual segmentation on clinically accepted software. For each image in the 2D acquisitions, slice volume was calculated and global LV volumes were estimated via summation across the LV using multiple slices. Real-time imaging data was reconstructed using different image exposure times and frame rates to evaluate the effect of temporal resolution on measured function in each slice via ACS. Finally, global volumetric function of ectopic and non-ectopic beats was measured using ACS in patients with arrhythmias. RESULTS ACS provides global LV volume measurements that are not significantly different from manual quantification of retrospectively gated cine images in sinus rhythm patients. With an exposure time of 95.2 ms and a frame rate of > 89 frames per second, golden-angle real-time imaging accurately captures hemodynamic function over a range of patient heart rates. In four patients with frequent ectopic contractions, initial quantification of the impact of ectopic beats on hemodynamic function was demonstrated. CONCLUSION User-initialized active contours and golden-angle real-time radial CMR can be used to determine time-varying LV function in patients. These methods will be very useful for the assessment of LV function in patients with frequent arrhythmias.
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Affiliation(s)
- Francisco Contijoch
- Department of Bioengineering, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, 7th Floor, Rm 103, Philadelphia, PA, 1903, USA.
| | | | - Kelly Rogers
- Cardiovascular Division, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Hannah Rears
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
| | | | - Paul Yushkevich
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
| | - Joseph Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, 1903, USA.
| | - Robert C Gorman
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, 1903, USA.
| | - Yuchi Han
- Cardiovascular Division, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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Schultz G, Gallichan D, Weber H, Witschey WRT, Honal M, Hennig J, Zaitsev M. Image reconstruction in k-space from MR data encoded with ambiguous gradient fields. Magn Reson Med 2015; 73:857-64. [PMID: 24777559 PMCID: PMC4617561 DOI: 10.1002/mrm.25152] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 12/09/2013] [Accepted: 01/08/2014] [Indexed: 11/11/2022]
Abstract
PURPOSE In this work, the limits of image reconstruction in k-space are explored when non-bijective gradient fields are used for spatial encoding. THEORY The image space analogy between parallel imaging and imaging with non-bijective encoding fields is partially broken in k-space. As a consequence, it is hypothesized and proven that ambiguities can only be resolved partially in k-space, and not completely as is the case in image space. METHODS Image-space and k-space based reconstruction algorithms for multi-channel radiofrequency data acquisitions are programmed and tested using numerical simulations as well as in vivo measurement data. RESULTS The hypothesis is verified based on an analysis of reconstructed images. It is found that non-bijective gradient fields have the effect that densely sampled autocalibration data, used for k-space reconstruction, provide less information than a separate scan of the receiver coil sensitivity maps, used for image space reconstruction. Consequently, in k-space only the undersampling artifact can be unfolded, whereas in image space, it is also possible to resolve aliasing that is caused by the non-bijectivity of the gradient fields. CONCLUSION For standard imaging, reconstruction in image space and in k-space is nearly equivalent, whereas there is a fundamental difference with practical consequences for the selection of image reconstruction algorithms when non-bijective encoding fields are involved.
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Affiliation(s)
- Gerrit Schultz
- Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
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McGarvey JR, Kondo N, Witschey WRT, Takebe M, Aoki C, Burdick JA, Spinale FG, Gorman JH, Pilla JJ, Gorman RC. Injectable microsphere gel progressively improves global ventricular function, regional contractile strain, and mitral regurgitation after myocardial infarction. Ann Thorac Surg 2015; 99:597-603. [PMID: 25524397 PMCID: PMC4314332 DOI: 10.1016/j.athoracsur.2014.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/05/2014] [Accepted: 09/09/2014] [Indexed: 11/20/2022]
Abstract
BACKGROUND There is continued need for therapies which reverse or abate the remodeling process after myocardial infarction (MI). In this study, we evaluate the longitudinal effects of calcium hydroxyapatite microsphere gel on regional strain, global ventricular function, and mitral regurgitation (MR) in a porcine MI model. METHODS Twenty-five Yorkshire swine were enrolled. Five were dedicated weight-matched controls. Twenty underwent posterolateral infarction by direct ligation of the circumflex artery and its branches. Infarcted animals were randomly divided into the following 4 groups: 1-week treatment; 1-week control; 4-week treatment; and 4-week control. After infarction, animals received either twenty 150 μL calcium hydroxyapatite gel or saline injections within the infarct. At their respective time points, echocardiograms, cardiac magnetic resonance imaging, and tissue were collected for evaluation of MR, regional and global left ventricular function, wall thickness, and collagen content. RESULTS Global and regional left ventricular functions were depressed in all infarcted subjects at 1 week compared with healthy controls. By 4-weeks post-infarction, global function had significantly improved in the calcium hydroxyapatite group compared with infarcted controls (ejection fraction 0.485 ± 0.019 vs 0.38 ± 0.017, p < 0.01). Similarly, regional borderzone radial contractile strain (16.3% ± 1.5% vs 11.2% ± 1.5%, p = 0.04), MR grade (0.4 ± 0.2 vs 1.2 ± 0.2, p = 0.04), and infarct thickness (7.8 ± 0.5 mm vs 4.5 ± 0.2 mm, p < 0.01) were improved at this time point in the treatment group compared with infarct controls. CONCLUSIONS Calcium hydroxyapatite injection after MI progressively improves global left ventricular function, borderzone function, and mitral regurgitation. Using novel biomaterials to augment infarct material properties is a viable alternative in the current management of heart failure.
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Affiliation(s)
- Jeremy R McGarvey
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Norihiro Kondo
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Walter R T Witschey
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Manabu Takebe
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Chikashi Aoki
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason A Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Francis G Spinale
- Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - James J Pilla
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
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Pilla JJ, Koomalsingh KJ, McGarvey JR, Witschey WRT, Dougherty L, Gorman JH, Gorman RC. Regional myocardial three-dimensional principal strains during postinfarction remodeling. Ann Thorac Surg 2015; 99:770-8. [PMID: 25620591 DOI: 10.1016/j.athoracsur.2014.10.067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/27/2014] [Accepted: 10/31/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND The purpose of this study was to quantify myocardial three-dimensional (3D) principal strains as the left ventricle (LV) remodels after myocardial infarction (MI). Serial quantification of myocardial strains is important for understanding the mechanical response of the LV to MI. Principal strains convert the 3D LV wall-based strain matrix with three normal and three shear elements, to a matrix with three nonzero normal elements, thereby eliminating the shear elements, which are difficult to physically interpret. METHODS The study was designed to measure principal strains of the remote, border zone, and infarct regions in a porcine model of post-MI LV remodeling. Magnetic resonance imaging was used to measure function and strain at baseline, 1 week, and 4 weeks after infarct. Principal strain was measured using 3D acquisition and the optical flow method for displacement tracking. RESULTS Principal strains were altered as the LV remodeled. Maximum principal strain magnitude decreased in all regions, including the noninfarcted remote, while maximum principal strain angles rotated away from the radial direction in the border zone and infarct. Minimum principal strain magnitude followed a similar pattern; however, strain angles were altered in all regions. Evolution of principal strains correlated with adverse LV remodeling. CONCLUSIONS Using a state-of-the-art imaging and optical flow method technique, 3D principal strains can be measured serially after MI in pigs. Results are consistent with progressive infarct stretching as well as with decreased contractile function in the border zone and remote myocardial regions.
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Affiliation(s)
- James J Pilla
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kevin J Koomalsingh
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jeremy R McGarvey
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Walter R T Witschey
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Larry Dougherty
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
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Abstract
There is great interest to use magnetic resonance imaging (MRI) for non-invasive assessment of myocardial disease in ischemic and non-ischemic cardiomyopathies. Recently, there has been a renewed interest to use a magnetic resonance imaging (MRI) technique utilizing spin locking radiofrequency (RF) pulses, called T1ρ MRI. The spin locking RF pulse creates sensitivity to some mechanisms of nuclear relaxation such as 1H exchange between water and amide, amine and hydroxyl functional groups in molecules; consequently, there is the potential to non-invasively, and without exogenous contrast agents, obtain important molecular information from diseased myocardial tissue. The purpose of this article is to review and critically examine the recent published literature in the field related to T1ρ MRI of myocardial disease.
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Affiliation(s)
- Yuchi Han
- Cardiovascular Division, Department of Medicine, Perelman School of Medicine, Hospital of the University of Pennsylvania, 9022 Gates, 3400 Spruce Street, Philadelphia, PA, USA
| | - Timo Liimatainen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Robert C. Gorman
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, 7th floor, Rm 103, Philadelphia, PA 19104, USA
| | - Walter R. T. Witschey
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, 7th floor, Rm 103, Philadelphia, PA 19104, USA
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Naha PC, Zaki AA, Hecht E, Chorny M, Chhour P, Blankemeyer E, Yates DM, Witschey WRT, Litt HI, Tsourkas A, Cormode DP. Dextran coated bismuth-iron oxide nanohybrid contrast agents for computed tomography and magnetic resonance imaging. J Mater Chem B 2014; 2:8239-8248. [PMID: 25485115 DOI: 10.1039/c4tb01159g] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bismuth nanoparticles have been proposed as a novel CT contrast agent, however few syntheses of biocompatible bismuth nanoparticles have been achieved. We herein report the synthesis of composite bismuth-iron oxide nanoparticles (BION) that are based on a clinically approved, dextran-coated iron oxide formulation; the particles have the advantage of acting as contrast agents for both CT and MRI. BION were synthesized and characterized using various analytical methods. BION CT phantom images revealed that the X-ray attenuation of the different formulations was dependent upon the amount of bismuth present in the nanoparticle, while T2-weighted MRI contrast decreased with increasing bismuth content. No cytotoxicity was observed in Hep G2 and BJ5ta cells after 24 hours incubation with BION. The above properties, as well as the yield of synthesis and bismuth inclusion efficiency, led us to select the Bi-30 formulation for in vivo experiments, performed in mice using a micro-CT and a 9.4 T MRI system. X-ray contrast was observed in the heart and blood vessels over a 2 hour period, indicating that Bi-30 has a prolonged circulation half-life. Considerable signal loss in T2-weighted MR images was observed in the liver compared to pre-injection scans. Evaluation of the biodistribution of Bi-30 revealed that bismuth is excreted via the urine, with significant concentrations found in the kidneys and urine. In vitro experiments confirmed the degradability of Bi-30. In summary, dextran coated BION are biocompatible, biodegradable, possess strong X-ray attenuation properties and also can be used as T2-weighted MR contrast agents.
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Affiliation(s)
- Pratap C Naha
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ajlan Al Zaki
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Elizabeth Hecht
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael Chorny
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Peter Chhour
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Eric Blankemeyer
- Small Animal Imaging Facility, University of Pennsylvania, PA, USA
| | - Douglas M Yates
- Nanoscale Characterization Facility, University of Pennsylvania, PA, USA
| | - Walter R T Witschey
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA ; Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Harold I Litt
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew Tsourkas
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - David P Cormode
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA ; Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, PA, USA
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McGarvey JR, Kondo N, Takebe M, Koomalsingh KJ, Witschey WRT, Barker AJ, Markl M, Takebayashi S, Shimaoka T, Gorman JH, Gorman RC, Pilla JJ. Directed epicardial assistance in ischemic cardiomyopathy: flow and function using cardiac magnetic resonance imaging. Ann Thorac Surg 2013; 96:577-85. [PMID: 23810178 DOI: 10.1016/j.athoracsur.2013.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/01/2013] [Accepted: 04/02/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Heart failure after myocardial infarction (MI) is a result of increased myocardial workload, adverse left ventricular (LV) geometric remodeling, and less efficient LV fluid movement. In this study we utilize cardiac magnetic resonance imaging to evaluate ventricular function and flow after placement of a novel directed epicardial assist device. METHODS Five swine underwent posterolateral MI and were allowed to remodel for 12 weeks. An inflatable bladder was positioned centrally within the infarct and secured with mesh. The device was connected to an external gas exchange pump, which inflated and deflated in synchrony with the cardiac cycle. Animals then underwent cardiac magnetic resonance imaging during active epicardial assistance and with no assistance. RESULTS Active epicardial assistance of the infarct showed immediate improvement in LV function and intraventricular flow. Ejection fraction significantly improved from 26.0% ± 4.9% to 37.3% ± 4.5% (p < 0.01). End-systolic volume (85.5 ± 12.7 mL versus 70.1 ± 11.9 mL, p < 0.01) and stroke volume (28.5 ± 4.4 mL versus 39.9 ± 3.1 mL, p = 0.03) were also improved with assistance. End-diastolic volume and regurgitant fraction did not change with treatment. Regional LV flow improved both qualitatively and quantitatively during assistance. Unassisted infarct regional flow showed highly discoordinate blood movement with very slow egress from the posterolateral wall. Large areas of stagnant flow were also identified. With assistance, posterolateral wall blood velocities improved significantly during both systole (26.4% ± 3.2% versus 12.6% ± 1.2% maximum velocity; p < 0.001) and diastole (54.3% ± 9.3% versus 24.2% ± 2.5% maximum velocity; p < 0.01). CONCLUSIONS Directed epicardial assistance can improve LV function and flow in ischemic cardiomyopathy. This novel device may provide a valuable alternative to currently available heart failure therapies.
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Affiliation(s)
- Jeremy R McGarvey
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104-5156, USA
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Schultz G, Weber H, Gallichan D, Witschey WRT, Welz AM, Cocosco CA, Hennig J, Zaitsev M. Radial imaging with multipolar magnetic encoding fields. IEEE Trans Med Imaging 2011; 30:2134-2145. [PMID: 21843982 DOI: 10.1109/tmi.2011.2164262] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present reconstruction methods for radial magnetic resonance imaging (MRI) data which were spatially encoded using a pair of orthogonal multipolar magnetic fields for in-plane encoding and parallel imaging. It is shown that a direct method exists in addition to iterative reconstruction. Standard direct projection reconstruction algorithms can be combined with a previously developed direct reconstruction for multipolar encoding fields acquired with Cartesian trajectories. The algorithm is simplified by recasting the reconstruction problem into polar coordinates. In this formulation distortion and aliasing become separate effects. Distortion occurs only along the radial direction and aliasing along the azimuthal direction. Moreover, aliased points are equidistantly distributed in this representation, and, consequently, Cartesian SENSE is directly applicable with highly effective unfolding properties for radio-frequency coils arranged with a radial symmetry. The direct and iterative methods are applied to simulated data to analyze basic properties of the algorithms and for the first time also measured in vivo data are presented. The results are compared to linear spatial encoding using a radial trajectory and quadrupolar encoding using a Cartesian trajectory. The direct reconstruction gives good results for fully sampled datasets. Undersampled datasets, however, show star-shaped artifacts, which are significantly reduced with the iterative reconstruction.
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Affiliation(s)
- Gerrit Schultz
- Department of Radiology, Medical Physics, University Medical Center Freiburg, 79106 Freiburg, Germany.
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Witschey WRT, Cocosco CA, Gallichan D, Schultz G, Weber H, Welz A, Hennig J, Zaitsev M. Localization by nonlinear phase preparation and k-space trajectory design. Magn Reson Med 2011; 67:1620-32. [PMID: 22127679 DOI: 10.1002/mrm.23146] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 06/21/2011] [Accepted: 07/20/2011] [Indexed: 11/08/2022]
Abstract
A technique is described to localize MR signals from a target volume using nonlinear pulsed magnetic fields and spatial encoding trajectories designed using local k-space theory. The concept of local k-space is outlined theoretically, and this principle is applied to simulated phantom and cardiac MRI data in the presence of surface and quadrupolar gradient coil phase modulation. Phantom and in vivo human brain images are obtained using a custom, high-performance quadrupolar gradient coil integrated with a whole-body 3-T MRI system to demonstrate target localization using three-dimensional T 2*-weighted spoiled gradient echo, two-dimensional segmented, multiple gradient encoded spin echo, and three-dimensional balanced steady-state free precession acquisitions. This method may provide a practical alternative to selective radiofrequency excitation at ultra-high-field, particularly for steady-state applications where repetition time (TR) must be minimized and when the amount of energy deposited in human tissues is prohibitive. There are several limitations to the approach including the spatial variation in resolution, high frequency aliasing artifacts, and spatial variation in echo times and contrast.
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Fenty MC, Dodge GR, Kassey VB, Witschey WRT, Borthakur A, Reddy R. Quantitative cartilage degeneration associated with spontaneous osteoarthritis in a guinea pig model. J Magn Reson Imaging 2011; 35:891-8. [PMID: 22128105 DOI: 10.1002/jmri.22867] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 09/30/2011] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To determine (i) the feasibility and intra- and inter-scan reproducibility of T(1ρ) MRI in assessing cartilage degeneration in a guinea pig model with naturally occurring joint disease that closely mimics human osteoarthritis (OA), (ii) demonstrate the sensitivity of T(1ρ) MRI in assessing the age dependent cartilage degeneration in OA progression as compared to histopathological changes. MATERIALS AND METHODS Duncan-Hartley guinea pigs were obtained at various ages and maintained under an IACUC approved protocol. The left hind stifle joint was imaged using T(1ρ) MRI on a 9.4 Tesla Varian horizontal 20 cm bore scanner using a custom surface coil. Reproducibility of T(1ρ) MRI was assessed using 4-month-old guinea pigs (N = 3). Three age cohorts; 3 month (N = 8), 5 month (N = 6), and 9 month (N = 5), were used to determine the age-dependent osteoarthritic changes as measured by T(1ρ) MRI. Validation of age-dependent cartilage degeneration was confirmed by histology and Safranin-O staining. RESULTS T(1ρ) values obtained in the cartilage of the stifle joint in guinea pigs were highly reproducible with an inter-scan mean coefficient of variation (CV) of 6.57% and a maximum intra-scan CV of 9.29%. Mean cartilage T(1ρ) values in animals with late stage cartilage degeneration were 56.3-56.9 ms (5-9 month cohorts) were both significantly (P < 0.01) higher than that obtained from 3-month-old cohort (44 ms) demonstrating an age-dependent variation. T(1ρ) was shown to be significantly greater than T(2) . T(1ρ) dispersion was observed in this animal model for the first time showing an increase of 45% between 500 Hz and 1500 Hz spin-locking frequency. Cartilage thickness measurements were calculated from single mid-coronal histology sections from same animals used for T(1ρ) MRI. Thickness calculations showed insignificant differences between 3- and 5-month cohorts and was significantly decreased by 9 months of age (P < 0.01). A moderate correlation (R(2) = 0.45) existed between T(1ρ) values and signal intensity of Safranin-O stain. CONCLUSION The data presented demonstrate that T(1ρ) MRI is highly reproducible in this spontaneous model of OA and may serve as a noninvasive tool to characterize joint cartilage degeneration during OA. Age-dependent changes, verified with histological measurements of proteoglycan loss, correlated with T(1ρ) across different age groups. T(1ρ) has adequate dynamic range and is sensitive to detect and track the progression of cartilage degeneration in the guinea pig model before gross anatomical changes such as cartilage thinning has occurred. This study presents a technological advancement that would permit longitudinal studies of evaluating disease-modifying therapies useful for treating human OA.
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Affiliation(s)
- Matthew C Fenty
- CMROI, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
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30
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Witschey WRT, Pilla JJ, Ferrari G, Koomalsingh K, Haris M, Hinmon R, Zsido G, Gorman JH, Gorman RC, Reddy R. Rotating frame spin lattice relaxation in a swine model of chronic, left ventricular myocardial infarction. Magn Reson Med 2011; 64:1453-60. [PMID: 20677236 DOI: 10.1002/mrm.22543] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
T1ρ relaxation times were quantified in a swine model of chronic, left ventricular myocardial infarction. It was found that there were low frequency relaxation mechanisms that suppress endogenous contrast at low spin-lock amplitudes and in T2-weighted images. A moderate amplitude spin-locking pulse could overcome these relaxation mechanisms. Relaxation dispersion data were measured over a range of RF field amplitudes, and a model was formulated to include dipole-dipole relaxation modulated by molecular rotation and an apparent exchange mechanism. These techniques may find some use in the clinic for the observation of chronic, left ventricular cardiac remodeling.
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Affiliation(s)
- Walter R T Witschey
- Department of Radiology, Medical Physics, University Hospital Freiburg, Freiburg im Breisgau, Germany.
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Mosher TJ, Zhang Z, Reddy R, Boudhar S, Milestone BN, Morrison WB, Kwoh CK, Eckstein F, Witschey WRT, Borthakur A. Knee articular cartilage damage in osteoarthritis: analysis of MR image biomarker reproducibility in ACRIN-PA 4001 multicenter trial. Radiology 2011; 258:832-42. [PMID: 21212364 DOI: 10.1148/radiol.10101174] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE To prospectively determine the reproducibility of quantitative magnetic resonance (MR) imaging biomarkers of the morphology and composition (spin lattice relaxation time in rotating frame [T1-ρ], T2) of knee cartilage in a multicenter multivendor trial involving patients with osteoarthritis (OA) and asymptomatic control subjects. MATERIALS AND METHODS This study was HIPAA compliant and approved by the institutional review committees of the participating sites, with written informed consent obtained from all participants. Fifty subjects from five sites who were deemed to have normal knee joints (n = 18), mild OA (n = 16), or moderate OA (n = 16) on the basis of Kellgren-Lawrence scores were enrolled. Each participant underwent four sequential 3-T knee MR imaging examinations with use of the same imager and with 2-63 days (median, 18 days) separating the first and last examinations. Water-excited three-dimensional T1-weighted gradient-echo imaging, T1-ρ imaging, and T2 mapping of cartilage in the axial and coronal planes were performed. Biomarker reproducibility was determined by using intraclass correlation coefficients (ICCs) and root-mean-square coefficients of variation (RMS CVs, expressed as percentages). RESULTS Morphometric biomarkers had high reproducibility, with ICCs of 0.989 or greater and RMS CVs lower than 4%. The largest differences between the healthy subjects and the patients with radiographically detected knee OA were those in T1-ρ values, but precision errors were relatively large. Reproducibility of T1-ρ values was higher in the thicker patellar cartilage (ICC range, 0.86-0.93; RMS CV range, 14%-18%) than in the femorotibial joints (ICC range, 0.20-0.84; RMS CV range, 7%-19%). Good to high reproducibility of T2 was observed, with ICCs ranging from 0.61 to 0.98 and RMS CVs ranging from 4% to 14%. CONCLUSION MR imaging measurements of cartilage morphology, T2, and patellar T1-ρ demonstrated moderate to excellent reproducibility in a clinical trial network.
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Affiliation(s)
- Timothy J Mosher
- Department of Radiology, Penn State University College of Medicine, Penn State University Hospital, 500 University Dr, Hershey, PA 17033, USA.
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Witschey WRT, Borthakur A, Fenty M, Kneeland BJ, Lonner JH, McArdle EL, Sochor M, Reddy R. T1rho MRI quantification of arthroscopically confirmed cartilage degeneration. Magn Reson Med 2010; 63:1376-82. [PMID: 20432308 DOI: 10.1002/mrm.22272] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nine asymptomatic subjects and six patients underwent T(1)rho MRI to determine whether Outerbridge grade 1 or 2 cartilage degeneration observed during arthroscopy could be detected noninvasively. MRI was performed 2-3 months postarthroscopy, using sagittal T(1)-weighted and axial and coronal T(1)rho MRI, from which spatial T(1)rho relaxation maps were calculated from segmented T(1)-weighted images. Median T(1)rho relaxation times of patients with arthroscopically documented cartilage degeneration and asymptomatic subjects were significantly different (P < 0.001), and median T(1)rho exceeded asymptomatic articular cartilage median T(1)rho by 2.5 to 9.2 ms. In eight observations of mild cartilage degeneration at arthroscopy (Outerbridge grades 1 and 2), mean compartment T(1)rho was elevated in five, but in all observations, large foci of increased T(1)rho were observed. It was determined that T(1)rho could detect some, but not all, Outerbridge grade 1 and 2 cartilage degeneration but that a larger patient population is needed to determine the sensitivity to these changes.
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Affiliation(s)
- Walter R T Witschey
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Witschey WRT, Borthakur A, Elliott MA, Magland J, McArdle EL, Wheaton A, Reddy R. Spin-locked balanced steady-state free-precession (slSSFP). Magn Reson Med 2010; 62:993-1001. [PMID: 19672947 DOI: 10.1002/mrm.22092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A spin-locked balanced steady-state free-precession (slSSFP) pulse sequence is described that combines a balanced gradient-echo acquisition with an off-resonance spin-lock pulse for fast MRI. The transient and steady-state magnetization trajectory was solved numerically using the Bloch equations and was shown to be similar to balanced steady-state free-precession (bSSFP) for a range of T(2)/T(1) and flip angles, although the slSSFP steady-state could be maintained with considerably lower radio frequency (RF) power. In both simulations and brain scans performed at 7T, slSSFP was shown to exhibit similar contrast and signal-to-noise ratio (SNR) efficiency to bSSFP, but with significantly lower power.
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Witschey WRT, Borthakur A, Elliott MA, Fenty M, Sochor MA, Wang C, Reddy R. T1rho-prepared balanced gradient echo for rapid 3D T1rho MRI. J Magn Reson Imaging 2008; 28:744-54. [PMID: 18777535 DOI: 10.1002/jmri.21444] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a T1rho-prepared, balanced gradient echo (b-GRE) pulse sequence for rapid three-dimensional (3D) T1rho relaxation mapping within the time constraints of a clinical exam (<10 minutes), examine the effect of acquisition on the measured T1rho relaxation time and optimize 3D T1rho pulse sequences for the knee joint and spine. MATERIALS AND METHODS A pulse sequence consisting of inversion recovery-prepared, fat saturation, T1rho-preparation, and b-GRE image acquisition was used to obtain 3D volume coverage of the patellofemoral and tibiofemoral cartilage and lower lumbar spine. Multiple T1rho-weighted images at various contrast times (spin-lock pulse duration [TSL]) were used to construct a T1rho relaxation map in both phantoms and in the knee joint and spine in vivo. The transient signal decay during b-GRE image acquisition was corrected using a k-space filter. The T1rho-prepared b-GRE sequence was compared to a standard T1rho-prepared spin echo (SE) sequence and pulse sequence parameters were optimized numerically using the Bloch equations. RESULTS The b-GRE transient signal decay was found to depend on the initial T1rho-preparation and the corresponding T1rho map was altered by variations in the point spread function with TSL. In a two compartment phantom, the steady state response was found to elevate T1rho from 91.4+/-6.5 to 293.8+/-31 and 66.9+/-3.5 to 661+/-207 with no change in the goodness-of-fit parameter R2. Phase encoding along the longest cartilage dimension and a transient signal decay k-space filter retained T1rho contrast. Measurement of T1rho using the T1rho-prepared b-GRE sequence matches standard T1rho-prepared SE in the medial patellar and lateral patellar cartilage compartments. T1rho-preparedb-GRE T1rho was found to have low interscan variability between four separate scans. Mean patellar cartilage T1rho was elevated compared to femoral and tibial cartilage T1rho. CONCLUSION The T1rho-prepared b-GRE acquisition rapidly and reliably accelerates T1rho quantification of tissues offset partially by a TSL-dependent point spread function.
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Affiliation(s)
- Walter R T Witschey
- Metabolic Magnetic Resonance Research and Computing Center, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA.
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Wang C, Auerbach JD, Witschey WRT, Balderston RA, Reddy R, Borthakur A. Advances in Magnetic Resonance Imaging for the assessment of degenerative disc disease of the lumbar spine. ACTA ACUST UNITED AC 2007; 19:65-71. [PMID: 18037984 DOI: 10.1053/j.semss.2007.04.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The intervertebral disc is characterized by a tension-resisting annulus fibrosus, and a compression-resisting nucleus pulposus composed largely of proteoglycan. Both the annulus and the nucleus function in concert to provide the disc with mechanical stability. Early disc degeneration begins in the nucleus with proteoglycan depletion. Quantitative MRI techniques have been developed to non-invasively quantify the earliest degenerative changes that occur within the disc. Our ability to identify and quantify these early biochemical changes will provide a better understanding of the pathophysiology of disc degeneration and facilitate the study of interventions that aim to halt or reverse the degenerative process.
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Affiliation(s)
- Chenyang Wang
- Graduate Student, Department of Bioengineering University of Pennsylvania, Philadelphia, PA 19104
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Witschey WRT, Borthakur A, Elliott MA, Mellon E, Niyogi S, Wallman DJ, Wang C, Reddy R. Artifacts in T1 rho-weighted imaging: compensation for B(1) and B(0) field imperfections. J Magn Reson 2007; 186:75-85. [PMID: 17291799 PMCID: PMC1995435 DOI: 10.1016/j.jmr.2007.01.015] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 01/23/2007] [Accepted: 01/23/2007] [Indexed: 05/13/2023]
Abstract
The origin of spin locking image artifacts in the presence of B(0) and B(1) magnetic field imperfections is shown theoretically using the Bloch equations and experimentally at low (omega(1) << Delta omega(0)), intermediate (omega(1) approximately Delta omega(0)) and high (omega(1) >> Delta omega(0)) spin locking field strengths. At low spin locking fields, the magnetization is shown to oscillate about an effective field in the rotating frame causing signature banding artifacts in the image. At high spin lock fields, the effect of the resonance offset Deltao mega(0) is quenched, but imperfections in the flip angle cause oscillations about the omega(1) field. A new pulse sequence is presented that consists of an integrated spin echo and spin lock experiment followed by magnetization storage along the -z-axis. It is shown that this sequence almost entirely eliminates banding artifacts from both types of field inhomogeneities at all spin locking field strengths. The sequence was used to obtain artifact free images of agarose in inhomogeneous B(0) and B(1) fields, off-resonance spins in fat and in vivo human brain images at 3 T. The new pulse sequence can be used to probe very low frequency (0-400 Hz) dynamic and static interactions in tissues without contaminating B(0) and B(1) field artifacts.
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Affiliation(s)
- Walter R T Witschey
- Graduate Group in Biochemistry and Molecular Biophysics and MMRRCC, University of Pennsylvania, B1 Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104-6100, USA.
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Witschey WRT, Borthakur A, Elliott MA, Mellon E, Niyogi S, Wang C, Reddy R. Compensation for spin-lock artifacts using an off-resonance rotary echo in T1rhooff-weighted imaging. Magn Reson Med 2007; 57:2-7. [PMID: 17191245 PMCID: PMC2877388 DOI: 10.1002/mrm.21134] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The origin of image artifacts in an off-resonance spin-locking experiment is shown to be imperfections in the excitation flip angle. A pulse sequence for off-resonance spin locking is implemented that compensates for imperfections in the excitation flip angle through an off-resonance rotary echo. The off-resonance rotary echo alternates the frequency offset and phase of the RF transmitter during two spin-locking pulses of equal duration. The underlying theory is detailed, and MR images demonstrate the effectiveness of the technique in agarose gel phantoms and in in vivo human brain at 3T.
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Affiliation(s)
- Walter R T Witschey
- Department of Biochemistry & Molecular Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA.
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