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Glemser PA, Rotkopf LT, Ziener CH, Beuthien-Baumann B, Weru V, Kopp-Schneider A, Schlemmer HP, Dimitrakopoulou-Strauss A, Sachpekidis C. Hybrid imaging with [ 68Ga]PSMA-11 PET-CT and PET-MRI in biochemically recurrent prostate cancer. Cancer Imaging 2022; 22:53. [PMID: 36138437 PMCID: PMC9502876 DOI: 10.1186/s40644-022-00489-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [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: 06/14/2022] [Accepted: 09/06/2022] [Indexed: 11/10/2022] Open
Abstract
AIM To compare [68Ga]PSMA-11 PET-CT, [68Ga]PSMA-11 PET-MRI and MRI in a cohort of prostate cancer (PCa) patients in biochemical recurrence after initial curative therapy. MATERIALS AND METHODS Fifty-three patients with biochemically recurrent PCa underwent whole-body [68Ga]PSMA-11 PET-CT 1 hour post-injection (p.i.) followed by [68Ga]PSMA-11 PET-MRI 2.5 hours p.i., including a multiparametric MRI pelvic protocol examination. Imaging data analysis consisted of visual (qualitative) evaluation of the PET-CT, PET-MRI and MRI scans, as well as semi-quantitative and quantitative analyses of the PET and MRI data, including calculation of the parameters standardized uptake value (SUV) and apparent diffusion coefficient (ADC) derived from the PCa lesions. Association analysis was performed between imaging and clinical data, including PSA level and Gleason score. The results were considered significant for p-values less than 0.05 (p < 0.05). RESULTS The hybrid imaging modalities [68Ga]PSMA-11 PET-CT and PET-MRI were positive in more patients than MRI alone. In particular, PET-CT detected lesions suggestive of PCa relapse in 34/53 (64.2%), PET-MRI in 36/53 (67.9%) and MRI in 23/53 patients (43.4%). While no significant differences in lesion detection rate were observed between PET-CT and PET-MRI, the latter was particularly efficient in detection of local recurrences in the prostate bed mainly due to the contribution of the MRI part of the modality. Association analysis revealed a statistically significant increase in the probability of a positive scan with increasing PSA levels for all imaging modalities. Accordingly, there was no significant association between scan positivity rate and Gleason score for any imaging modality. No significant correlation was observed between SUV and ADC values in lymph node metastases. CONCLUSION [68Ga]PSMA-11 PET-CT and PET-MRI provide equally good detection rates for PCa recurrence, both outperforming stand-alone MRI.
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Affiliation(s)
- P A Glemser
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - L T Rotkopf
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, 69120, Heidelberg, Germany
| | - C H Ziener
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - B Beuthien-Baumann
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - V Weru
- Department of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - A Kopp-Schneider
- Department of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - H P Schlemmer
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - A Dimitrakopoulou-Strauss
- Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69210, Heidelberg, Germany
| | - C Sachpekidis
- Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69210, Heidelberg, Germany.
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2
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Rotkopf LT, Buschle LR, Schlemmer HP, Ziener CH. Influence of diffusion on transverse relaxation rates and phases of an ensemble of magnetic spheres. J Magn Reson 2022; 341:107259. [PMID: 35779309 DOI: 10.1016/j.jmr.2022.107259] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 05/30/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
In quantitative susceptibility mapping, the tissue susceptibility is determined from the magnitude and phase of the gradient echo signal, which is influenced by the interplay of complex susceptibility and diffusion effect. Herein, we analytically analyze the influence of diffusion on magnitude and phase images generated by randomly arranged magnetic spheres as a model of intracerebral iron depositions. We demonstrate that both gradient and spin echo relaxation rate constants have a strong and nonlinear dependence on diffusion strength and give empirical formulas for magnitude and phase. This may be used in the future to improve QSM processing methods. In addition, we show that, in theory, combined acquisitions of gradient and spin echo can be used to determine the dimension of the magnetic spheres and the diffusion strength.
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Affiliation(s)
- L T Rotkopf
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
| | - L R Buschle
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
| | - H-P Schlemmer
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
| | - C H Ziener
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany.
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3
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Wehrse E, Klein L, Rotkopf LT, Stiller W, Finke M, Echner G, Glowa C, Heinze S, Ziener CH, Schlemmer HP, Kachelrieß M, Sawall S. Ultrahigh resolution whole body photon counting computed tomography as a novel versatile tool for translational research from mouse to man. Z Med Phys 2022:S0939-3889(22)00066-6. [PMID: 35868888 DOI: 10.1016/j.zemedi.2022.06.002] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/18/2022] [Accepted: 06/19/2022] [Indexed: 11/19/2022]
Abstract
X-ray computed tomography (CT) is a cardinal tool in clinical practice. It provides cross-sectional images within seconds. The recent introduction of clinical photon-counting CT allowed for an increase in spatial resolution by more than a factor of two resulting in a pixel size in the center of rotation of about 150 µm. This level of spatial resolution is in the order of dedicated preclinical micro-CT systems. However so far, the need for different dedicated clinical and preclinical systems often hinders the rapid translation of early research results to applications in men. This drawback might be overcome by ultra-high resolution (UHR) clinical photon-counting CT unifying preclinical and clinical research capabilities in a single machine. Herein, the prototype of a clinical UHR PCD CT (SOMATOM CounT, Siemens Healthineers, Forchheim, Germany) was used. The system comprises a conventional energy-integrating detector (EID) and a novel photon-counting detector (PCD). While the EID provides a pixel size of 0.6 mm in the centre of rotation, the PCD provides a pixel size of 0.25 mm. Additionally, it provides a quantification of photon energies by sorting them into up to four distinct energy bins. This acquisition of multi-energy data allows for a multitude of applications, e.g. pseudo-monochromatic imaging. In particular, we examine the relation between spatial resolution, image noise and administered radiation dose for a multitude of use-cases. These cases include ultra-high resolution and multi-energy acquisitions of mice administered with a prototype bismuth-based contrast agent (nanoPET Pharma, Berlin, Germany) as well as larger animals and actual patients. The clinical EID provides a spatial resolution of about 9 lp/cm (modulation transfer function at 10%, MTF10%) while UHR allows for the acquisition of images with up to 16 lp/cm allowing for the visualization of all relevant anatomical structures in preclinical and clinical specimen. The spectral capabilities of the system enable a variety of applications previously not available in preclinical research such as pseudo-monochromatic images. Clinical ultra-high resolution photon-counting CT has the potential to unify preclinical and clinical research on a single system enabling versatile imaging of specimens and individuals ranging from mice to man.
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Affiliation(s)
- E Wehrse
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
| | - L Klein
- Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany; Division of X-ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - L T Rotkopf
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - W Stiller
- Diagnostic and Interventional Radiology (DIR), Heidelberg University Hospital, Heidelberg, Germany
| | - M Finke
- Diagnostic and Interventional Radiology (DIR), Heidelberg University Hospital, Heidelberg, Germany
| | - G Echner
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - C Glowa
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Radiation Oncology and Radiotherapy, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - S Heinze
- Institute of Forensic and Traffic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - C H Ziener
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - H-P Schlemmer
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - M Kachelrieß
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany; Division of X-ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - S Sawall
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany; Division of X-ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg, Germany.
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4
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Rotkopf LT, Wehrse E, Kampf T, Vogel P, Schlemmer HP, Ziener CH. Spin echo formation in muscle tissue. Phys Rev E 2021; 104:034419. [PMID: 34654209 DOI: 10.1103/physreve.104.034419] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/13/2021] [Indexed: 11/07/2022]
Abstract
Determination of the spin echo signal evolution and of transverse relaxation rates is of high importance for microstructural modeling of muscle tissue in magnetic resonance imaging. So far, numerically exact solutions for the NMR signal dynamics in muscle tissue models have been reported only for the gradient echo free induction decay, with spin echo problems usually solved by approximate methods. In this work, we modeled the spin echo signal numerically exact by discretizing the radial dimension of the Bloch-Torrey equation and expanding the angular dependency in terms of even Chebyshev polynomials. This allows us to express the time dependence of the local magnetization as a closed-form matrix expression. Using this method, we were able to accurately capture the spin echo local and total magnetization dynamics. The obtained transverse relaxation rates showed a high concordance with random walker and finite-element simulations. We could demonstrate that in cases of smaller diffusion coefficients, the commonly used strong collision approximation significantly underestimates the true value considerably. Instead, the limiting behavior in this regime is correctly described either by the full solution or by the slow diffusion approximation. Experimentally measured transverse relaxation rates of a mouse limb muscle showed an angular dependence in accordance with the theoretical prediction.
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Affiliation(s)
- L T Rotkopf
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany
| | - E Wehrse
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany.,Würzburg University Hospital, Department of Neuroradiology, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
| | - P Vogel
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany
| | - H-P Schlemmer
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
| | - C H Ziener
- Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
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5
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Sawall S, Klein L, Wehrse E, Rotkopf LT, Amato C, Maier J, Schlemmer HP, Ziener CH, Heinze S, Kachelrieß M. Threshold-dependent iodine imaging and spectral separation in a whole-body photon-counting CT system. Eur Radiol 2021; 31:6631-6639. [PMID: 33713171 PMCID: PMC8379121 DOI: 10.1007/s00330-021-07786-0] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/20/2021] [Accepted: 02/12/2021] [Indexed: 11/01/2022]
Abstract
OBJECTIVE To evaluate the dual-energy (DE) performance and spectral separation with respect to iodine imaging in a photon-counting CT (PCCT) and compare it to dual-source CT (DSCT) DE imaging. METHODS A semi-anthropomorphic phantom extendable with fat rings equipped with iodine vials is measured in an experimental PCCT. The system comprises a PC detector with two energy bins (20 keV, T) and (T, eU) with threshold T and tube voltage U. Measurements using the PCCT are performed at all available tube voltages (80 to 140 kV) and threshold settings (50-90 keV). Further measurements are performed using a conventional energy-integrating DSCT. Spectral separation is quantified as the relative contrast media ratio R between the energy bins and low/high images. Image noise and dose-normalized contrast-to-noise ratio (CNRD) are evaluated in resulting iodine images. All results are validated in a post-mortem angiography study. RESULTS R of the PC detector varies between 1.2 and 2.6 and increases with higher thresholds and higher tube voltage. Reference R of the EI DSCT is found as 2.20 on average overall phantoms. Maximum CNRD in iodine images is found for T = 60/65/70/70 keV for 80/100/120/140 kV. The highest CNRD of the PCCT is obtained using 140 kV and is decreasing with decreasing tube voltage. All results could be confirmed in the post-mortem angiography study. CONCLUSION Intrinsically acquired DE data are able to provide iodine images similar to conventional DSCT. However, PCCT thresholds should be chosen with respect to tube voltage to maximize image quality in retrospectively derived image sets. KEY POINTS • Photon-counting CT allows for the computation of iodine images with similar quality compared to conventional dual-source dual-energy CT. • Thresholds should be chosen as a function of the tube voltage to maximize iodine contrast-to-noise ratio in derived image sets. • Image quality of retrospectively computed image sets can be maximized using optimized threshold settings.
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Affiliation(s)
- S Sawall
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. .,Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany.
| | - L Klein
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.,Department of Physics and Astronomy, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 226, 69120, Heidelberg, Germany
| | - E Wehrse
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany.,Division of Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - L T Rotkopf
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany.,Division of Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - C Amato
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany
| | - J Maier
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - H-P Schlemmer
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany.,Division of Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - C H Ziener
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany.,Division of Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - S Heinze
- Institute of Forensic and Traffic Medicine, University Hospital Heidelberg, Voßstraße 2, 69115, Heidelberg, Germany
| | - M Kachelrieß
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, 69120, Heidelberg, Germany
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6
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Kurz FT, Buschle LR, Rotkopf LT, Herzog FS, Sterzik A, Schlemmer HP, Kampf T, Bendszus M, Heiland S, Ziener CH. Dependence of the frequency distribution around a sphere on the voxel orientation. Z Med Phys 2021; 31:403-419. [PMID: 33750628 DOI: 10.1016/j.zemedi.2021.01.005] [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] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 11/29/2022]
Abstract
Microscopically small magnetic field inhomogeneities within an external static magnetic field cause a free induction decay in magnetic resonance imaging that generally exhibits two transverse components that are usually summarized to a complex entity. The Fourier transform of the complex-valued free induction decay is the purely real and positive-valued frequency distribution which allows an easy interpretation of the underlying dephasing mechanism. Typically, the frequency distribution inside a cubic voxel as caused by a spherical magnetic field inhomogeneity is determined by a histogram technique in terms of subdivision of the whole voxel into smaller subvoxels. A faster and more accurate computation is achieved by analytical expressions for the frequency distribution that are derived in this work. In contrast to the usually assumed simplified case of a spherical voxel, we also consider the tilt angles of the cubic voxel to the external magnetic field. The typical asymmetric form of the frequency distribution is reproduced and analyzed for the more realistic case of a cubic voxel. We observe a splitting of frequency distribution peaks for increasing tilt of the cubic voxel against the direction of the external magnetic field in analogy to the case for dephasing around cylindrical, vessel-like objects inside cubic voxels. These results are of value, e.g., for the analysis of susceptibility-weighted images or in quantitative susceptibility imaging since the reconstruction of these images is performed in cubic-shaped voxels.
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Affiliation(s)
- F T Kurz
- Heidelberg University Hospital, Dept. of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - L R Buschle
- German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, INF 227, 69120 Heidelberg, Germany
| | - L T Rotkopf
- German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - F S Herzog
- German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, INF 227, 69120 Heidelberg, Germany
| | - A Sterzik
- German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, INF 227, 69120 Heidelberg, Germany
| | - H-P Schlemmer
- German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Dept. of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany; Würzburg University Hospital, Dept. of Neuroradiology, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
| | - M Bendszus
- Heidelberg University Hospital, Dept. of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - S Heiland
- Heidelberg University Hospital, Dept. of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - C H Ziener
- Heidelberg University Hospital, Dept. of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; German Cancer Research Center, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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7
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Wehrse E, Klein L, Rotkopf LT, Wagner WL, Uhrig M, Heußel CP, Ziener CH, Delorme S, Heinze S, Kachelrieß M, Schlemmer HP, Sawall S. Photon-counting detectors in computed tomography: from quantum physics to clinical practice. Radiologe 2021; 61:1-10. [PMID: 33598788 DOI: 10.1007/s00117-021-00812-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2021] [Indexed: 12/19/2022]
Abstract
Over the last decade, a fundamentally new type of computed tomography (CT) detectors has proved its superior capabilities in both physical and preclinical evaluations and is now approaching the stage of clinical practice. These detectors are able to discriminate single photons and quantify their energy and are hence called photon-counting detectors. Among the promising benefits of this technology are improved radiation dose efficiency, increased contrast-to-noise ratio, reduced metal artifacts, improved spatial resolution, simultaneous multi-energy acquisitions, and the prospect of multi-phase imaging within a single acquisition using multiple contrast agents. Taking the conventional energy-integrating detectors as a reference, the authors demonstrate the technical principles of this new technology and provide phantom and patient images acquired by a whole-body photon-counting CT. These images serve as a basis for discussing the potential future of clinical CT.
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Affiliation(s)
- E Wehrse
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany.
| | - L Klein
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
| | - L T Rotkopf
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - W L Wagner
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg, German Center for Lung Research, Heidelberg, Germany
| | - M Uhrig
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - C P Heußel
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg, German Center for Lung Research, Heidelberg, Germany
- Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik, University of Heidelberg, Heidelberg, Germany
| | - C H Ziener
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - S Delorme
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - S Heinze
- Institute of Forensic and Traffic Medicine, University Hospital Heidelberg, Voßstraße 2, 69115, Heidelberg, Germany
| | - M Kachelrieß
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
| | - H-P Schlemmer
- Division of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - S Sawall
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
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8
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Wehrse E, Sawall S, Klein L, Glemser P, Delorme S, Schlemmer HP, Kachelrieß M, Uhrig M, Ziener CH, Rotkopf LT. Potential of ultra-high-resolution photon-counting CT of bone metastases: initial experiences in breast cancer patients. NPJ Breast Cancer 2021; 7:3. [PMID: 33398008 PMCID: PMC7782694 DOI: 10.1038/s41523-020-00207-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [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: 04/06/2020] [Accepted: 11/12/2020] [Indexed: 01/01/2023] Open
Abstract
Conventional CT scanners use energy-integrating detectors (EIDs). Photon-counting detector (PCD) computed tomography (CT) utilizes a CT detector technology based on smaller detector pixels capable of counting single photons and in addition discriminating their energy. Goal of this study was to explore the potential of higher spatial resolution for imaging of bone metastases. Four female patients with histologically confirmed breast cancer and bone metastases were included between July and October 2019. All patients underwent conventional EID CT scans followed by a high resolution non-contrast experimental PCD CT scan. Ultra-high resolution (UHR) reconstruction kernels were used to reconstruct axial slices with voxel sizes of 0.3 mm × 0.3 mm (inplane) × 1 mm (z-direction). Four radiologists blinded for patient identity assessed the images and compared the quality to conventional CT using a qualitative Likert scale. In this case series, we present images of bone metastases in breast cancer patients using an experimental PCD CT scanner and ultra-high-resolution kernels. A tendency to both a smaller inter-reader variability in the structural assessment of lesion sizes and in the readers' opinion to an improved visualization of lesion margins and content was observed. In conclusion, while further studies are warranted, PCD CT has a high potential for therapy monitoring in breast cancer.
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Affiliation(s)
- E Wehrse
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany.
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany.
| | - S Sawall
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
| | - L Klein
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
| | - P Glemser
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
| | - S Delorme
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
| | - H-P Schlemmer
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
| | - M Kachelrieß
- Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Division of X-Ray Imaging and Computed Tomography, German Cancer Research Center, Heidelberg, Germany
| | - M Uhrig
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
| | - C H Ziener
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
| | - L T Rotkopf
- Division of Radiology, German Cancer Research Center, Heidelberg, Germany
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9
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Wagner WL, Hellbach K, Fiedler MO, Salg GA, Wehrse E, Ziener CH, Merle U, Eckert C, Weber TF, Stiller W, Wielpütz MO, Dullin C, Kenngott HG, Schlemmer HP, Weigand MA, Schirmacher P, Longerich T, Kauczor HU, Kommoss FKF, Schwab C. [Microvascular changes in COVID-19]. Radiologe 2020; 60:934-942. [PMID: 32857175 PMCID: PMC7453182 DOI: 10.1007/s00117-020-00743-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Clinically, coronavirus disease 2019 (COVID-19) is associated with a wide range of symptoms, which can range from mild complaints of an upper respiratory infection to life-threatening hypoxic respiratory insufficiency and multiorgan failure. OBJECTIVE The initially identified pulmonary damage patterns, such as diffuse alveolar damage in acute lung failure, are accompanied by new findings that draw a more complex scenario. These include microvascular involvement and a wide range of associated pathologies of multiple organ systems. A back-scaling of microstructural vascular changes is possible via targeted correlation of pathological autopsy results with radiological imaging. MATERIAL AND METHODS Radiological and pathological correlation as well as microradiological imaging to investigate microvascular involvement in fatal COVID-19. RESULTS The cases of two COVID-19 patients are presented. Patient 1 showed a relative hypoperfusion in lung regions that did not have typical COVID-19 infiltrates; the targeted post-mortem correlation also showed subtle signs of microvascular damage even in these lung sections. Patient 2 showed both radiologically and pathologically advanced typical COVID-19 destruction of lung structures and the case illustrates the damage patterns of the blood-air barrier. The perfusion deficit of the intestinal wall shown in computed tomography of patient 2 could not ultimately clearly be microscopically attributed to intestinal microvascular damage. CONCLUSION In addition to microvascular thrombosis, our results indicate a functional pulmonary vasodysregulation as part of the pathophysiology during the vascular phase of COVID-19. The clinical relevance of autopsies and the integration of radiological imaging findings into histopathological injury patterns must be emphasized for a better understanding of COVID-19.
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Affiliation(s)
- W L Wagner
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland.
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland.
| | - K Hellbach
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - M O Fiedler
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - G A Salg
- Neue Technologien und Datenwissenschaften/3D-Biodruck Einheit, Klinik für Allgemein‑, Viszeral-, und Transplantationschirurgie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - E Wehrse
- Abteilung Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Deutschland
- Medizinische Fakultät, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Deutschland
| | - C H Ziener
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
- Abteilung Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Deutschland
| | - U Merle
- Klinik für Gastroenterologie, Infektionen, Vergiftungen, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - C Eckert
- Pathologisches Institut, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - T F Weber
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland
| | - W Stiller
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - M O Wielpütz
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - C Dullin
- Institut für Diagnostische und Interventionelle Radiologie, Universitätsmedizin Göttingen, Göttingen, Deutschland
| | - H G Kenngott
- Neue Technologien und Datenwissenschaften/3D-Biodruck Einheit, Klinik für Allgemein‑, Viszeral-, und Transplantationschirurgie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - H-P Schlemmer
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
- Abteilung Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Deutschland
| | - M A Weigand
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - P Schirmacher
- Pathologisches Institut, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
- TI Biobank, Deutsches Zentrum für Infektionsforschung (DZIF), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - T Longerich
- Pathologisches Institut, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - H-U Kauczor
- Klinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Deutschland
- Zentrum für Translationale Lungenforschung (TLRC), Deutsches Zentrum für Lungenforschung (DZL), Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - F K-F Kommoss
- Pathologisches Institut, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - C Schwab
- Pathologisches Institut, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
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Ziener CH, Kampf T, Schlemmer HP, Buschle LR. Spin echoes: full numerical solution and breakdown of approximative solutions. J Phys Condens Matter 2019; 31:155101. [PMID: 30641507 DOI: 10.1088/1361-648x/aafe21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The spin echo signal from vessels in Krogh's capillary model as well in the random distribution vessel model are studied by numerically solving the Bloch-Torrey equation. A comparison is made with the Gaussian local phase approximation, the Gaussian phase approximation and the strong-collision approximation. Differences between the Gaussian local phase approximation and the Gaussian phase approximation are explained. In the intermediate diffusion regime, the full numerical solution shows oscillations which are absent in any of the approximate solutions. In the limit of large diffusion coefficients, where the approximations become exact, the signal shows a linear-exponential decay governed by a single parameter. The features of the exact numerical solution can be explained by an analytically solvable discrete two-level model. There is a one-to-one correspondence between the different diffusion regimes and the three cases of the damped harmonic oscillator.
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Affiliation(s)
- C H Ziener
- German Cancer Research Center DKFZ, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. University Hospital Heidelberg, Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
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11
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Buschle LR, Kurz FT, Kampf T, Schlemmer HP, Ziener CH. Spin dephasing around randomly distributed vessels. J Magn Reson 2019; 299:12-20. [PMID: 30529850 DOI: 10.1016/j.jmr.2018.11.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
We analyze the gradient echo signal in the presence of blood vessel networks. Both, diffusion and susceptibility effects are analytically emphasized within the Bloch-Torrey equation. Solving this equation, we present the first exact description of the local magnetization around a single vessel. This allows us to deduce the gradient echo signal of parallel vessels randomly distributed in a plane, which is valid for arbitrary mean vessel diameters in the range of physiological relevant blood volume fractions. Thus, the results are potentially relevant for gradient echo measurements of blood vessel networks with arbitrary vessel size.
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Affiliation(s)
- L R Buschle
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - F T Kurz
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany; Würzburg University Hospital, Department of Neuroradiology, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
| | - H P Schlemmer
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - C H Ziener
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
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12
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Ziener CH, Kampf T, Kurz FT, Schlemmer HP, Buschle LR. Pseudo-diffusion effects in lung MRI. J Magn Reson 2019; 299:1-11. [PMID: 30529849 DOI: 10.1016/j.jmr.2018.11.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
Magnetic resonance imaging of lung tissue is strongly influenced by susceptibility effects between spin-bearing water molecules and air-filled alveoli. The measured lineshape, however, also depends on the interplay between susceptibility effects and blood-flow around alveoli that can be approximated as pseudo-diffusion. Both effects are quantitatively described by the Bloch-Torrey-equation, which was so far only solved for dephasing on the alveolar surface. In this work, we extend this model to the whole range of physiological relevant air volume fractions. The results agree very well with in vivo measurements in human lung tissue.
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Affiliation(s)
- C H Ziener
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany; Würzburg University Hospital, Department of Neuroradiology, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
| | - F T Kurz
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - H P Schlemmer
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - L R Buschle
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
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13
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Affiliation(s)
- C. H. Ziener
- German Cancer Research Center-DKFZ, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - T. Kampf
- Department of Diagnostic and Interventional Neuroradiology, Würzburg University Hospital, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
- Department of Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - H.-P. Schlemmer
- German Cancer Research Center-DKFZ, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - L. R. Buschle
- German Cancer Research Center-DKFZ, E010 Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
- Faculty of Physics and Astronomy, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
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14
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Kurz FT, Buschle LR, Hahn A, Jende JME, Bendszus M, Heiland S, Ziener CH. Diffusion effects in myelin sheath free induction decay. J Magn Reson 2018; 297:61-75. [PMID: 30366221 DOI: 10.1016/j.jmr.2018.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
Myelin sheath microstructure and composition produce MR signal decay characteristics that can be used to evaluate status and outcome of demyelinating disease. We extend a recently proposed model of neuronal magnetic susceptibility, that accounts for both the structural and inherent anisotropy of the myelin sheath, by including the whole dynamic range of diffusion effects. The respective Bloch-Torrey equation for local spin dephasing is solved with a uniformly convergent perturbation expansion method, and the resulting magnetization decay is validated with a numerical solution based on a finite difference method. We show that a variation of diffusion strengths can lead to substantially different MR signal decay curves. Our results may be used to adjust or control simulations for water diffusion in neuronal structures.
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Affiliation(s)
- F T Kurz
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
| | - L R Buschle
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, INF 227, D-69120 Heidelberg, Germany
| | - A Hahn
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - J M E Jende
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - M Bendszus
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - S Heiland
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - C H Ziener
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
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15
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Buschle LR, Kurz FT, Kampf T, Wagner WL, Duerr J, Stiller W, Konietzke P, Wünnemann F, Mall MA, Wielpütz MO, Schlemmer HP, Ziener CH. Dephasing and diffusion on the alveolar surface. Phys Rev E 2017; 95:022415. [PMID: 28297921 DOI: 10.1103/physreve.95.022415] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 06/06/2023]
Abstract
We propose a surface model of spin dephasing in lung tissue that includes both susceptibility and diffusion effects to provide a closed-form solution of the Bloch-Torrey equation on the alveolar surface. The nonlocal susceptibility effects of the model are validated against numerical simulations of spin dephasing in a realistic lung tissue geometry acquired from synchotron-based μCT data sets of mouse lung tissue, and against simulations in the well-known Wigner-Seitz model geometry. The free induction decay is obtained in dependence on microscopic tissue parameters and agrees very well with in vivo lung measurements at 1.5 Tesla to allow a quantification of the local mean alveolar radius. Our results are therefore potentially relevant for the clinical diagnosis and therapy of pulmonary diseases.
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Affiliation(s)
- L R Buschle
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - F T Kurz
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany
| | - W L Wagner
- University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - J Duerr
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
- University of Heidelberg, Department of Translational Pulmonology, Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - W Stiller
- University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - P Konietzke
- University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - F Wünnemann
- University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
| | - M A Mall
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
- University of Heidelberg, Department of Translational Pulmonology, Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - M O Wielpütz
- University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
- University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), Member of German Center for Lung Research (DZL), Im Neuenheimer Feld 156, 69120 Heidelberg, Germany
| | - H P Schlemmer
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - C H Ziener
- German Cancer Research Center - DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
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Kurz FT, Buschle LR, Kampf T, Zhang K, Schlemmer HP, Heiland S, Bendszus M, Ziener CH. Spin dephasing in a magnetic dipole field around large capillaries: Approximative and exact results. J Magn Reson 2016; 273:83-97. [PMID: 27794269 DOI: 10.1016/j.jmr.2016.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
We present an analytical solution of the Bloch-Torrey equation for local spin dephasing in the magnetic dipole field around a capillary and for ensembles of capillaries, and adapt this solution for the study of spin dephasing around large capillaries. In addition, we provide a rigorous mathematical derivation of the slow diffusion approximation for the spin-bearing particles that is used in this regime. We further show that, in analogy to the local magnetization, the transverse magnetization of one MR imaging voxel in the regime of static dephasing (where diffusion effects are not considered) is merely the first term of a series expansion that constitutes the signal in the slow diffusion approximation. Theoretical results are in agreement with experimental data for capillaries in rat muscle at 7T.
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Affiliation(s)
- F T Kurz
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
| | - L R Buschle
- German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - K Zhang
- German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany
| | - H P Schlemmer
- German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany
| | - S Heiland
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - M Bendszus
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - C H Ziener
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany
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Kurz FT, Freitag M, Schlemmer HP, Bendszus M, Ziener CH. Grundlagen und Anwendungen der suszeptibilitätsgewichteten Bildgebung. Radiologe 2016; 56:124-36. [DOI: 10.1007/s00117-015-0069-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
We analyze the free induction decay of nuclear spins under the influence of restricted diffusion in a magnetic dipole field around cylindrical objects. In contrast to previous publications no restrictions or simplifications concerning the diffusion process are made. By directly solving the Bloch-Torrey equation, analytical expressions for the magnetization are given in terms of an eigenfunction expansion. The field strength-dependent complex nature of the eigenvalue spectrum significantly influences the shape of the free induction decay. As the dipole field is the lowest order of the multipole expansion, the obtained results are important for understanding fundamental mechanisms of spin dephasing in many other applied fields of nuclear magnetic resonance such as biophysics or material science. The analytical methods are applied to interpret the spin dephasing in the free induction decay in cardiac muscle and skeletal muscle. A simple expression for the relevant transverse relaxation time is found in terms of the underlying microscopic parameters of the muscle tissue. The analytical results are in agreement with experimental data. These findings are important for the correct interpretation of magnetic resonance images for clinical diagnosis at all magnetic field strengths and therapy of cardiovascular diseases.
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Affiliation(s)
- C H Ziener
- German Cancer Research Center-DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Heidelberg University, Department of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - F T Kurz
- German Cancer Research Center-DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Heidelberg University, Department of Neuroradiology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - T Kampf
- University of Würzburg, Department of Experimental Physics 5, Am Hubland, 97074 Würzburg, Germany
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Kurz FT, Schlemmer HP, Heiland S, Bendszus M, Ziener CH. Quantitative magnetic resonance imaging of microvascular changes in KHT sarcoma. Cancer Imaging 2014. [PMCID: PMC4242431 DOI: 10.1186/1470-7330-14-s1-p13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Ziener CH, Bauer WR, Schlemmer HP. Spindephasierung im Kroghschen Kapillarmodell des Myokards. ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ziener CH, Schlemmer HP. Dephasierung durch eingeschränkte Diffusion in einem linearen Gradienten. ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ziener CH, Kampf T, Reents G, Schlemmer HP, Bauer WR. Spin dephasing in a magnetic dipole field. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:051908. [PMID: 23004789 DOI: 10.1103/physreve.85.051908] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 03/12/2012] [Indexed: 06/01/2023]
Abstract
Transverse relaxation by dephasing in an inhomogeneous field is a general mechanism in physics, for example, in semiconductor physics, muon spectroscopy, or nuclear magnetic resonance. In magnetic resonance imaging the transverse relaxation provides information on the properties of several biological tissues. Since the dipole field is the most important part of the multipole expansion of the local inhomogeneous field, dephasing in a dipole field is highly important in relaxation theory. However, there have been no analytical solutions which describe the dephasing in a magnetic dipole field. In this work we give a complete analytical solution for the dephasing in a magnetic dipole field which is valid over the whole dynamic range.
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Affiliation(s)
- C H Ziener
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Ziener CH, Kampf T, Jakob PM, Bauer WR. Diffusion effects on the CPMG relaxation rate in a dipolar field. J Magn Reson 2010; 202:38-42. [PMID: 19853483 DOI: 10.1016/j.jmr.2009.09.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 09/15/2009] [Accepted: 09/26/2009] [Indexed: 05/28/2023]
Abstract
The diffusion in the magnetic dipolar field around a sphere is considered. The diffusion is restricted to the space between two concentric spheres, where the inner sphere is the source of the magnetic dipolar field. Analytical expressions for the CPMG transverse relaxation rate as well as the free induction decay and the spin echo time evolution are given in the Gaussian approximation. The influence of the inter-echo time is analyzed. The limiting cases of small and large inter-echo times as well as the short and long time behavior are evaluated.
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Affiliation(s)
- C H Ziener
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Würzburg, Germany.
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Ziener CH, Glutsch S, Jakob PM, Bauer WR. Spin dephasing in the dipole field around capillaries and cells: numerical solution. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:046701. [PMID: 19905476 DOI: 10.1103/physreve.80.046701] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Indexed: 05/28/2023]
Abstract
We numerically solve the Bloch-Torrey equation by discretizing the differential operators in real space using finite differences. The differential equation is either solved directly in time domain as initial-value problem or in frequency domain as boundary-value problem. Especially the solution in time domain is highly efficient and suitable for arbitrary domains and dimensions. As examples, we calculate the average magnetization and the frequency distribution for capillaries and cells which are idealized as cylinders and spheres, respectively. The solution is compared with the commonly used Gaussian approximation and the strong-collision approximation. While these approximations become exact in limiting cases (small or large diffusion coefficient), they strongly deviate from the numerical solution for intermediate values of the diffusion coefficient.
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Affiliation(s)
- C H Ziener
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Würzburg, Germany
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Weber T, Ziener CH, Kampf T, Herold V, Bauer WR, Jakob PM. Measurement of apparent cell radii using a multiple wave vector diffusion experiment. Magn Reson Med 2009; 61:1001-6. [DOI: 10.1002/mrm.21848] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Ziener CH, Kampf T, Herold V, Jakob PM, Bauer WR, Nadler W. Frequency autocorrelation function of stochastically fluctuating fields caused by specific magnetic field inhomogeneities. J Chem Phys 2008; 129:014507. [DOI: 10.1063/1.2949097] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ziener CH, Kampf T, Melkus G, Herold V, Weber T, Reents G, Jakob PM, Bauer WR. Local frequency density of states around field inhomogeneities in magnetic resonance imaging: effects of diffusion. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:031915. [PMID: 17930279 DOI: 10.1103/physreve.76.031915] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/27/2007] [Indexed: 05/25/2023]
Abstract
A method describing NMR-signal formation in inhomogeneous tissue is presented which covers all diffusion regimes. For this purpose, the frequency distribution inside the voxel is described. Generalizing the results of the well-known static dephasing regime, we derive a formalism to describe the frequency distribution that is valid over the whole dynamic range. The expressions obtained are in agreement with the results obtained from Kubos line-shape theory. To examine the diffusion effects, we utilize a strong collision approximation, which replaces the original diffusion process by a simpler stochastic dynamics. We provide a generally valid relation between the frequency distribution and the local Larmor frequency inside the voxel. To demonstrate the formalism we give analytical expressions for the frequency distribution and the free induction decay in the case of cylindrical and spherical magnetic inhomogeneities. For experimental verification, we performed measurements using a single-voxel spectroscopy method. The data obtained for the frequency distribution, as well as the magnetization decay, are in good agreement with the analytic results, although experiments were limited by magnetic field gradients caused by an imperfect shim and low signal-to-noise ratio.
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Affiliation(s)
- C H Ziener
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074 Würzburg, Germany
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Ziener CH, Kampf T, Melkus G, Jakob PM, Bauer WR. Scaling laws for transverse relaxation times. J Magn Reson 2007; 184:169-75. [PMID: 17045825 DOI: 10.1016/j.jmr.2006.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 09/18/2006] [Accepted: 09/22/2006] [Indexed: 05/12/2023]
Abstract
Simple scaling laws are useful tools in understanding the effect of changing parameters in MRI experiments. In this paper the general scaling behavior of the transverse relaxation times is discussed. We consider the dephasing of spins diffusing around a field inhomogeneity inside a voxel. The strong collision approximation is used to describe the diffusion process. The obtained scaling laws are valid over the whole dynamic range from motional narrowing to static dephasing. The dependence of the relaxation times on the external magnetic field, diffusion coefficients of the surrounding medium, and the characteristic scale of the field inhomogeneity is analyzed. For illustration the generally valid scaling laws are applied to the special case of a capillary, usually used as a model of the myocardial BOLD effect.
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Affiliation(s)
- C H Ziener
- Bayerische Julius-Maximilians-Universität Würzburg, Institut für Experimentelle Physik 5, Am Hubland, 97074 Würzburg, Germany.
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Ziener CH, Bauer WR, Jakob PM. Frequency distribution and signal formation around a vessel. MAGMA 2005; 18:225-30. [PMID: 16175391 DOI: 10.1007/s10334-005-0122-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 07/19/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
We describe the NMR signal formation properties of a single vessel. Instead of assuming the frequency distribution to be a simple Lorentzian or Gaussian one, we take into account that the frequency distribution around the vessel is a complex function. Considering the static dephasing regime we find a relationship between signal formation and frequency distribution. Analytical expressions for the frequency distribution in a voxel and the magnetization decay are obtained. In the case of small volume fractions of blood and week magnetic fields the results can be used for describing signal formation processes in a vascular network. A relationship between the frequency distribution and the properties of the vascular network is derived. The magnetization decay in different time regimes is discussed. The result is relevant for describing signal formation processes around a vessel for arbitrary pulse sequences.
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Affiliation(s)
- C H Ziener
- Bayerische Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany.
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Abstract
We describe the NMR relaxation properties of magnetically labeled cells. The cells are labeled with magnetic nanoparticles (SPIO, USPIO), which generate susceptibility contrast. The geometry of the labeled cells and the surrounding tissue is considered. We assume that the magnetic nanoparticles accumulate to form a magnetic core of radius RC inside the cell. The correlation time tau, which describes the motion of spins around this core, is analyzed. Using the strong collision approach, explicit expressions are derived for the transverse relaxation rate R2* for tissue containing labeled cells as a function of the core radius, the diffusion coefficient, and the concentration of the nanoparticles. The predictions of this model agree well with numerical simulations and experimental data.
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Affiliation(s)
- C H Ziener
- Bayerische Julius-Maximilians-Universität Würzburg, Institut für Experimentelle Physik 5, Am Hubland, 97074 Würzburg, Germany.
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