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Ton N, Goncin U, Panahifar A, Chapman D, Wiebe S, Machtaler S. Developing a Microbubble-Based Contrast Agent for Synchrotron In-Line Phase Contrast Imaging. IEEE Trans Biomed Eng 2020; 68:1527-1535. [PMID: 33232220 DOI: 10.1109/tbme.2020.3040079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE X-ray phase contrast imaging generates contrast from refraction of X-rays, enhancing soft tissue contrast compared to conventional absorption-based imaging. Our goal is to develop a contrast agent for X-ray in-line phase contrast imaging (PCI) based on ultrasound microbubbles (MBs), by assessing size, shell material, and concentration. METHODS Polydisperse perfluorobutane-core lipid-shelled MBs were synthesized and size separated into five groups between 1 and 10 μm. We generated two size populations of polyvinyl-alcohol (PVA)-MBs, 2-3 μm and 3-4 μm, whose shells were either coated or integrated with iron oxide nanoparticles (SPIONs). Microbubbles were then embedded in agar at three concentrations: 5 × 107, 5 × 106 and 5 × 105 MBs/ml. In-line phase contrast imaging was performed at the Canadian Light Source with filtered white beam micro-computed tomography. Phase contrast intensity was measured by both counting detectable MBs, and comparing mean pixel values (MPV) in minimum and maximum intensity projections of the overall samples. RESULTS Individual lipid-MBs 6-10 μm, lipid-MBs 4-6 μm and PVA-MBs coated with SPIONs were detectable at each concentration. At the highest concentration, lipid-MBs 6-10 μm and 4-6 μm showed an overall increase in positive contrast, whereas at a moderate concentration, only lipid-MBs 6-10 μm displayed an increase. Negative contrast was also observed from two largest lipid-MBs at high concentration. CONCLUSION These data indicate that lipid-MBs larger than 4 μm are candidates for PCI, and 5 × 106 MBs/ml may be the lowest concentration suitable for generating visible phase contrast in vivo. SIGNIFICANCE Identifying a suitable MB for PCI may facilitate future clinical translation.
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Lång K, Arboleda C, Forte S, Wang Z, Prevrhal S, Koehler T, Kuhn N, David B, Jefimovs K, Kubik-Huch RA, Stampanoni M. Microbubbles as a contrast agent in grating interferometry mammography: an ex vivo proof-of-mechanism study. Eur Radiol Exp 2019; 3:19. [PMID: 31115796 PMCID: PMC6529489 DOI: 10.1186/s41747-019-0097-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 04/04/2019] [Indexed: 11/24/2022] Open
Abstract
Grating interferometry mammography (GIM) is an experimental breast imaging method at the edge of being clinically implemented. Besides attenuation, GIM can measure the refraction and scattering of x-rays resulting in differential phase contrast (DPC) and dark-field (DF) images. In this exploratory study, we assessed the feasibility of using microbubbles as a contrast agent in GIM. Two millilitres of microbubbles and iodine were respectively injected into ex vivo breast phantoms, consisting of fresh chicken breasts. Native and postcontrast images were acquired with a clinically compatible GIM setup, operated at 38 kVp, 14-s acquisition time, and with a dose of 1.3 mGy. The visibility of the contrast agents was analysed in a side-by-side comparison by three radiologists. The contrast-to-noise-ratio (CNR) was calculated for each contrast agent. We found that both contrast agents were judged to be visible by the readers. The mean CNR was 3.1 ± 1.9 for microbubbles in DF and 24.2 ± 6.5 for iodine in attenuation. In conclusion, this is a first proof-of-mechanism study that microbubbles could be used as a contrast agent in clinically compatible GIM, due to their scattering properties, which implies the potential use of a contrast agent with a high safety profile in x-ray-based breast imaging.
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Affiliation(s)
- Kristina Lång
- Swiss Light Source, ETH Zurich, Paul Scherrer Institute, 5232, Villigen, Switzerland. .,Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
| | - Carolina Arboleda
- Swiss Light Source, ETH Zurich, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Serafino Forte
- Department of Radiology, Kantonsspital Baden, Im Ergel 1, 5404, Baden, Switzerland
| | - Zhentian Wang
- Swiss Light Source, ETH Zurich, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sven Prevrhal
- Philips GmbH Innovative Technologies, Research Laboratories, Philips Research Hamburg, Röntgenstrasse 24-26, 22335, Hamburg, Germany
| | - Thomas Koehler
- Philips GmbH Innovative Technologies, Research Laboratories, Philips Research Hamburg, Röntgenstrasse 24-26, 22335, Hamburg, Germany
| | - Norbert Kuhn
- Philips GmbH Innovative Technologies, Research Laboratories, Philips Research Hamburg, Röntgenstrasse 24-26, 22335, Hamburg, Germany
| | - Bernd David
- Philips GmbH Innovative Technologies, Research Laboratories, Philips Research Hamburg, Röntgenstrasse 24-26, 22335, Hamburg, Germany
| | - Konstantins Jefimovs
- Swiss Light Source, ETH Zurich, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Rahel A Kubik-Huch
- Department of Radiology, Kantonsspital Baden, Im Ergel 1, 5404, Baden, Switzerland
| | - Marco Stampanoni
- Swiss Light Source, ETH Zurich, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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Wu D, Wong MD, Li Y, Fajardo L, Zheng B, Wu X, Liu H. Quantitative investigation of the edge enhancement in in-line phase contrast projections and tomosynthesis provided by distributing microbubbles on the interface between two tissues: a phantom study. Phys Med Biol 2017; 62:9357-9376. [PMID: 29161236 PMCID: PMC5731655 DOI: 10.1088/1361-6560/aa9548] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this study was to quantitatively investigate the ability to distribute microbubbles along the interface between two tissues, in an effort to improve the edge and/or boundary features in phase contrast imaging. The experiments were conducted by employing a custom designed tissue simulating phantom, which also simulated a clinical condition where the ligand-targeted microbubbles are self-aggregated on the endothelium of blood vessels surrounding malignant cells. Four different concentrations of microbubble suspensions were injected into the phantom: 0%, 0.1%, 0.2%, and 0.4%. A time delay of 5 min was implemented before image acquisition to allow the microbubbles to become distributed at the interface between the acrylic and the cavity simulating a blood vessel segment. For comparison purposes, images were acquired using three system configurations for both projection and tomosynthesis imaging with a fixed radiation dose delivery: conventional low-energy contact mode, low-energy in-line phase contrast and high-energy in-line phase contrast. The resultant images illustrate the edge feature enhancements in the in-line phase contrast imaging mode when the microbubble concentration is extremely low. The quantitative edge-enhancement-to-noise ratio calculations not only agree with the direct image observations, but also indicate that the edge feature enhancement can be improved by increasing the microbubble concentration. In addition, high-energy in-line phase contrast imaging provided better performance in detecting low-concentration microbubble distributions.
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Affiliation(s)
- Di Wu
- School of Electrical and Computer Engineering, University of Oklahoma, 110 West Boyd Street, Norman, OK 73019, United States of America
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