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Rice J, Bushman W, Roldán-Alzate A. Validation of Dynamic 3D MRI for Urodynamics Assessment Using an Anatomically Realistic In Vitro Model of the Bladder. J Biomech Eng 2024; 146:071007. [PMID: 38511303 PMCID: PMC11080948 DOI: 10.1115/1.4065110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 03/12/2024] [Accepted: 03/12/2024] [Indexed: 03/22/2024]
Abstract
Lowery urinary tract symptoms (LUTS) affect a large majority of the aging population. 3D Dynamic MRI shows promise as a noninvasive diagnostic tool that can assess bladder anatomy and function (urodynamics) while overcoming challenges associated with current urodynamic assessment methods. However, validation of this technique remains an unmet need. In this study, an anatomically realistic, bladder-mimicking in vitro flow model was created and used to systematically benchmark 3D dynamic MRI performance using a highly controllable syringe pump. Time-resolved volumes of the synthetic bladder model were obtained during simulated filling and voiding events and used to calculate volumetric flowrate. During MRI acquisitions, pressure during each event was recorded and used to create PV loops for work assessment. Error between control and MRI-derived volume for voiding and filling events exhibited 3.36% and 4.66% differences, respectively. A slight increase in average error was observed for MRI-derived flowrate when compared to the control flowrate (4.90% and 7.67% for voiding and filling, respectively). Overall, average error in segmented volumes increased with decreasing volume flowrate. Pressure drops were observed during voiding. Pressure increased during filling. Enhanced validation of novel 3D MRI urodynamics is achieved by using high-resolution PIV for visualizing and quantifying velocity inside the bladder model, which is not currently possible with 3D Dynamic MRI.
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Affiliation(s)
- James Rice
- Department of Mechanical Engineering, University of Wisconsin–Madison, Madison, WI 53705;Department of Radiology, University of Wisconsin–Madison, Madison, WI 53705
- University of Wisconsin–Madison
| | - Wade Bushman
- Department of Urology, University of Wisconsin–Madison, Madison, WI 53705
- University of Wisconsin–Madison
| | - Alejandro Roldán-Alzate
- Department of Radiology, University of Wisconsin–Madison, Madison, WI 53705;Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI 53705
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2
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Dunn A, Wagner S, Sussman D. Scoping review of magnetic resonance motion imaging phantoms. MAGMA (NEW YORK, N.Y.) 2024:10.1007/s10334-024-01164-9. [PMID: 38739218 DOI: 10.1007/s10334-024-01164-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 03/28/2024] [Accepted: 04/29/2024] [Indexed: 05/14/2024]
Abstract
To review and analyze the currently available MRI motion phantoms. Publications were collected from the Toronto Metropolitan University Library, PubMed, and IEEE Xplore. Phantoms were categorized based on the motions they generated: linear/cartesian, cardiac-dilative, lung-dilative, rotational, deformation or rolling. Metrics were extracted from each publication to assess the motion mechanisms, construction methods, as well as phantom validation. A total of 60 publications were reviewed, identifying 48 unique motion phantoms. Translational movement was the most common movement (used in 38% of phantoms), followed by cardiac-dilative (27%) movement and rotational movement (23%). The average degrees of freedom for all phantoms were determined to be 1.42. Motion phantom publications lack quantification of their impact on signal-to-noise ratio through standardized testing. At present, there is a lack of phantoms that are designed for multi-role as many currently have few degrees of freedom.
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Affiliation(s)
- Alexander Dunn
- Department of Electrical, Computer, and Biomedical Engineering, Toronto Metropolitan University, Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST) at Toronto Metropolitan University and St. Michael's Hospital, Toronto, Canada
| | - Sophie Wagner
- Department of Electrical, Computer, and Biomedical Engineering, Toronto Metropolitan University, Toronto, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST) at Toronto Metropolitan University and St. Michael's Hospital, Toronto, Canada
| | - Dafna Sussman
- Department of Electrical, Computer, and Biomedical Engineering, Toronto Metropolitan University, Toronto, Canada.
- Institute for Biomedical Engineering, Science and Technology (iBEST) at Toronto Metropolitan University and St. Michael's Hospital, Toronto, Canada.
- Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.
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3
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Degenhardt K, Schmidt S, Aigner CS, Kratzer FJ, Seiter DP, Mueller M, Kolbitsch C, Nagel AM, Wieben O, Schaeffter T, Schulz-Menger J, Schmitter S. Toward accurate and fast velocity quantification with 3D ultrashort TE phase-contrast imaging. Magn Reson Med 2024; 91:1994-2009. [PMID: 38174601 DOI: 10.1002/mrm.29978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE Traditional phase-contrast MRI is affected by displacement artifacts caused by non-synchronized spatial- and velocity-encoding time points. The resulting inaccurate velocity maps can affect the accuracy of derived hemodynamic parameters. This study proposes and characterizes a 3D radial phase-contrast UTE (PC-UTE) sequence to reduce displacement artifacts. Furthermore, it investigates the displacement of a standard Cartesian flow sequence by utilizing a displacement-free synchronized-single-point-imaging MR sequence (SYNC-SPI) that requires clinically prohibitively long acquisition times. METHODS 3D flow data was acquired at 3T at three different constant flow rates and varying spatial resolutions in a stenotic aorta phantom using the proposed PC-UTE, a Cartesian flow sequence, and a SYNC-SPI sequence as reference. Expected displacement artifacts were calculated from gradient timing waveforms and compared to displacement values measured in the in vitro flow experiments. RESULTS The PC-UTE sequence reduces displacement and intravoxel dephasing, leading to decreased geometric distortions and signal cancellations in magnitude images, and more spatially accurate velocity quantification compared to the Cartesian flow acquisitions; errors increase with velocity and higher spatial resolution. CONCLUSION PC-UTE MRI can measure velocity vector fields with greater accuracy than Cartesian acquisitions (although pulsatile fields were not studied) and shorter scan times than SYNC-SPI. As such, this approach is superior to traditional Cartesian 3D and 4D flow MRI when spatial misrepresentations cannot be tolerated, for example, when computational fluid dynamics simulations are compared to or combined with in vitro or in vivo measurements, or regional parameters such as wall shear stress are of interest.
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Affiliation(s)
- Katja Degenhardt
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Simon Schmidt
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christoph S Aigner
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
| | - Fabian J Kratzer
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Daniel P Seiter
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
| | - Max Mueller
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Kolbitsch
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
| | - Armin M Nagel
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
- Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin, USA
| | - Tobias Schaeffter
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- School of Imaging Science and Biomedical Engineering, King's College London, London, United Kingdom
- Department of Medical Engineering, Technical University of Berlin, Berlin, Germany
| | - Jeanette Schulz-Menger
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Working Group on Cardiovascular Magnetic Resonance, Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Department of Cardiology and Nephrology, HELIOS Hospital Berlin-Buch, Berlin, Germany
| | - Sebastian Schmitter
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Motovilova E, Aronowitz E, Vincent J, Shin J, Tan ET, Robb F, Taracila V, Sneag DB, Dyke JP, Winkler SA. Silicone-based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue-mimicking phantom design. Med Phys 2023. [PMID: 36737839 DOI: 10.1002/mp.16255] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 12/24/2022] [Accepted: 01/15/2023] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The development of materials with tailored signal intensity in MR imaging is critically important both for the reduction of signal from non-tissue hardware, as well as for the construction of tissue-mimicking phantoms. Silicone-based phantoms are becoming more popular due to their structural stability, stretchability, longer shelf life, and ease of handling, as well as for their application in dynamic imaging of physiology in motion. Moreover, silicone can be also used for the design of stretchable receive radio-frequency (RF) coils. PURPOSE Fabrication of materials with tailored signal intensity for MRI requires knowledge of precise T1 and T2 relaxation times of the materials used. In order to increase the range of possible relaxation times, silicone materials can be doped with gadolinium (Gd). In this work, we aim to systematically evaluate relaxation properties of Gd-doped silicone material at a broad range of Gd concentrations and at three clinically relevant magnetic field strengths (1.5 T, 3 T, and 7 T). We apply the findings for rendering silicone substrates of stretchable receive RF coils less visible in MRI. Moreover, we demonstrate early stage proof-of-concept applicability in tissue-mimicking phantom development. MATERIALS AND METHODS Ten samples of pure and Gd-doped Ecoflex silicone polymer samples were prepared with various Gd volume ratios ranging from 1:5000 to 1:10, and studied using 1.5 T and 3 T clinical and 7 T preclinical scanners. T1 and T2 relaxation times of each sample were derived by fitting the data to Bloch signal intensity equations. A receive coil made from Gd-doped Ecoflex silicone polymer was fabricated and evaluated in vitro at 3 T. RESULTS With the addition of a Gd-based contrast agent, it is possible to significantly change T2 relaxation times of Ecoflex silicone polymer (from 213 ms to 20 ms at 1.5 T; from 135 ms to 17 ms at 3 T; and from 111.4 ms to 17.2 ms at 7 T). T1 relaxation time is less affected by the introduction of the contrast agent (changes from 608 ms to 579 ms; from 802.5 ms to 713 ms at 3 T; from 1276 ms to 979 ms at 7 T). First results also indicate that liver, pancreas, and white matter tissues can potentially be closely mimicked using this phantom preparation technique. Gd-doping reduces the appearance of the silicone-based coil substrate during the MR scan by up to 81%. CONCLUSIONS Gd-based contrast agents can be effectively used to create Ecoflex silicone polymer-based phantoms with tailored T2 relaxation properties. The relative low cost, ease of preparation, stretchability, mechanical stability, and long shelf life of Ecoflex silicone polymer all make it a good candidate for "MR invisible" coil development and bears promise for tissue-mimicking phantom development applicability.
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Affiliation(s)
- Elizaveta Motovilova
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA.,Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Eric Aronowitz
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | | | - James Shin
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Ek Tsoon Tan
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | | | | | - Darryl B Sneag
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Jonathan P Dyke
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
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Oechtering TH, Roberts GS, Panagiotopoulos N, Wieben O, Reeder SB, Roldán-Alzate A. Clinical Applications of 4D Flow MRI in the Portal Venous System. Magn Reson Med Sci 2022; 21:340-353. [PMID: 35082218 PMCID: PMC9680553 DOI: 10.2463/mrms.rev.2021-0105] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 10/13/2021] [Indexed: 09/27/2023] Open
Abstract
Evaluation of the hemodynamics in the portal venous system plays an essential role in many hepatic pathologies. Changes in portal flow and vessel morphology are often indicative of disease.Routinely used imaging modalities, such as CT, ultrasound, invasive angiography, and MRI, often focus on either hemodynamics or anatomical imaging. In contrast, 4D flow MRI facilitiates a more comprehensive understanding of pathophysiological mechanisms by simultaneously and noninvasively acquiring time-resolved flow and anatomical information in a 3D imaging volume.Though promising, 4D flow MRI in the portal venous system is especially challenging due to small vessel calibers, slow flow velocities, and breathing motion. In this review article, we will discuss how to account for these challenges when planning and conducting 4D flow MRI acquisitions in the upper abdomen. We will address patient preparation, sequence acquisition, postprocessing, quality control, and analysis of 4D flow data.In the second part of this article, we will review potential clinical applications of 4D flow MRI in the portal venous system. The most promising area for clinical utilization is the diagnosis and grading of liver cirrhosis and its complications. Relevant parameters acquired by 4D flow MRI include the detection of reduced or reversed flow in the portal venous system, characterization of portosystemic collaterals, and impaired response to a meal challenge. In patients with cirrhosis, 4D flow MRI has the potential to address the major unmet need of noninvasive detection of gastroesophageal varices at high risk for bleeding. This could replace many unnecessary, purely diagnostic, and invasive esophagogastroduodenoscopy procedures, thereby improving patient compliance with follow-up. Moreover, 4D flow MRI offers unique insights and added value for surgical planning and follow-up of multiple hepatic interventions, including transjugular intrahepatic portosystemic shunts, liver transplantation, and hepatic disease in children. Lastly, we will discuss the path to clinical implementation and remaining challenges.
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Affiliation(s)
- Thekla H. Oechtering
- Department of Radiology, University of Wisconsin, Madison, WI, USA
- Department of Radiology, Universität zu Lübeck, Luebeck, Germany
| | - Grant S. Roberts
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Nikolaos Panagiotopoulos
- Department of Radiology, University of Wisconsin, Madison, WI, USA
- Department of Radiology, Universität zu Lübeck, Luebeck, Germany
| | - Oliver Wieben
- Department of Radiology, University of Wisconsin, Madison, WI, USA
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Scott B. Reeder
- Department of Radiology, University of Wisconsin, Madison, WI, USA
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
- Department of Mechanical Engineering, University of Wisconsin, Madison, WI, USA
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, USA
- Department of Emergency, University of Wisconsin Medicine, Madison, WI, USA
| | - Alejandro Roldán-Alzate
- Department of Radiology, University of Wisconsin, Madison, WI, USA
- Department of Mechanical Engineering, University of Wisconsin, Madison, WI, USA
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, USA
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Corrado PA, Barton GP, Francois CJ, Wieben O, Goss KN. Sildenafil administration improves right ventricular function on 4D flow MRI in young adults born premature. Am J Physiol Heart Circ Physiol 2021; 320:H2295-H2304. [PMID: 33861148 PMCID: PMC8289359 DOI: 10.1152/ajpheart.00824.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/30/2021] [Accepted: 04/13/2021] [Indexed: 11/22/2022]
Abstract
Extreme preterm birth conveys an elevated risk of heart failure by young adulthood. Smaller biventricular chamber size, diastolic dysfunction, and pulmonary hypertension may contribute to reduced ventricular-vascular coupling. However, how hemodynamic manipulations may affect right ventricular (RV) function and coupling remains unknown. As a pilot study, 4D flow MRI was used to assess the effect of afterload reduction and heart rate reduction on cardiac hemodynamics and function. Young adults born premature were administered sildenafil (a pulmonary vasodilator) and metoprolol (a β blocker) on separate days, and MRI with 4D flow completed before and after each drug administration. Endpoints include cardiac index (CI), direct flow fractions, and ventricular kinetic energy including E/A wave kinetic energy ratio. Sildenafil resulted in a median CI increase of 0.24 L/min/m2 (P = 0.02), mediated through both an increase in heart rate (HR) and stroke volume. Although RV ejection fraction improved only modestly, there was a significant increase (4% of end diastolic volume) in RV direct flow fraction (P = 0.04), consistent with hemodynamic improvement. Metoprolol administration resulted in a 5-beats/min median decrease in HR (P = 0.01), a 0.37 L/min/m2 median decrease in CI (P = 0.04), and a reduction in time-averaged kinetic energy (KE) in both ventricles (P < 0.01), despite increased RV diastolic E/A KE ratio (P = 0.04). Despite reduced right atrial workload, metoprolol significantly depressed overall cardiac systolic function. Sildenafil, however, increased CI and improved RV function, as quantified by the direct flow fraction. The preterm heart appears dependent on HR but sensitive to RV afterload manipulations.NEW & NOTEWORTHY We assessed the effect of right ventricular afterload reduction with sildenafil and heart rate reduction with metoprolol on cardiac hemodynamics and function in young adults born premature using 4D flow MRI. Metoprolol depressed cardiac function, whereas sildenafil improved cardiac function including right ventricular direct flow fraction by 4D flow, consistent with hemodynamic improvement. This suggests that the preterm heart is dependent on heart rate and sensitive to right ventricular afterload changes.
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Affiliation(s)
- Philip A Corrado
- Department of Medical Physics, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
| | - Gregory P Barton
- Department of Medical Physics, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
- Department of Medicine, University of Texas Southwestern, Dallas, Texas
| | - Christopher J Francois
- Department of Radiology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
- Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
- Department of Radiology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
| | - Kara N Goss
- Department of Medicine, University of Texas Southwestern, Dallas, Texas
- Department of Pediatrics, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
- Department of Medicine. University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin
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