Differential ultra-wideband microwave imaging for medical applications

Elektromagnetische Ultrabreitband-Sensorik und -Bildgebung bieten vielversprechende Perspektiven für verschiedene biomedizinische Anwendungen, da diese Wellen biologisches Gewebe durchdringen können. Dabei stellt der Einsatz von leistungsarmen und nichtionisierenden Mikrowellen eine gesundheitlich unbedenkliche Untersuchungsmethode dar. Eine der Herausforderungen im Bereich der ultrabreitbandigen Mikrowellensensorik ist dabei die Extraktion der diagnostisch relevanten Informationen aus den Messdaten, da aufgrund der komplexen Wellenausbreitung im Gewebe meist rechenaufwändige Methoden notwendig sind. Dieses Problem wird wesentlich vereinfacht, wenn sich die Streueigenschaften des zu untersuchenden Objektes zeitlich ändern. Diese zeitliche Varianz der Streueigenschaften kann mit Hilfe einer Differenzmessung über ein bestimmtes Zeitintervall ausgenutzt werden. Im Rahmen dieser Arbeit wird der differentielle Ansatz mittels Ultrabreitband-Sensorik für zwei medizinische Anwendungsszenarien betrachtet. Die dabei genutzten Messsysteme basieren auf dem M-Sequenzverfahren, welches an der Technischen Universität Ilmenau entwickelt wurde. Die erste Anwendung bezieht sich auf das nicht-invasive Temperaturmonitoring mittels Ultrabreitband-Technologie während einer Hyperthermiebehandlung. Hyperthermie ist eine Wärmetherapie zur Unterstützung onkologischer Behandlungen (z. B. Chemo- oder Strahlentherapie). Während einer solchen Behandlung wird das Tumorgewebe um 4 °C bis 8 °C erhöht. Dabei ist es wichtig, dass die Temperatur die obere Grenze von 45 °C nicht überschreitet. In diesem Zusammenhang bietet das differentielle Ultrabreitband-Monitoring eine vielversprechende Technik zur kontinuierlichen und nicht-invasiven Messung der Temperatur im Körperinneren. Der Ansatz basiert auf den temperaturabhängigen dielektrischen Eigenschaften von biologischem Gewebe. Dabei werden elektromagnetische Wellen mit einer geringen Leistung in das Untersuchungsmedium eingebracht, die sich gemäß den dielektrischen Eigenschaften von Gewebe ausbreiten. Wird eine Zielregion (bspw. Tumor) erwärmt, so ändern sich dessen dielektrische Eigenschaften, was zu einem sich ändernden Streuverhalten der elektromagnetischen Welle führt. Diese Änderungen können mittels Ultrabreitband-Sensorik erfasst werden. Für die Evaluierung der gemessenen Änderungen im Radarsignal ist es notwendig, die temperaturabhängigen dielektrischen Eigenschaften von Gewebe im Mikrowellenfrequenzbereich zu kennen. Aufgrund der wenigen in der Literatur vorhandenen temperaturabhängigen dielektrischen Eigenschaften von Gewebe über einen breiten Mikrowellenfrequenzbereich werden in dieser Arbeit die dielektrischen Eigenschaften für Leber, Muskel, Fett und Blut im Temperaturbereich zwischen 30 °C und 50 °C von 500 MHz bis 7 GHz erfasst. Hierzu wird zunächst ein Messaufbau für die temperaturabhängige dielektrische Spektroskopie von Gewebe, Gewebeersatz und Flüssigkeiten vorgestellt und die wesentlichen Einflussfaktoren auf die Messungen analysiert. Die Messdaten werden mit Hilfe eines temperaturabhängigen Cole-Cole Models modelliert, um die dielektrischen Eigenschaften für beliebige Werte im untersuchten Temperatur- und Frequenzbereich berechnen zu können. In einem weiteren Experiment wird die nicht-invasive Erfassung von Temperaturänderungen mittels Ultrabreitband-Technologie in einem experimentellen Messaufbau nachgewiesen. Die Ergebnisse zeigen, dass eine Temperaturänderung von 1 °C zu Differenzsignalen führt, welche mit der genutzten Ultrabreitband-Sensorik (M-Sequenz) detektierbar sind. Die zweite Anwendung befasst sich mit der kontrastbasierten Mikrowellen-Brustkrebsbildgebung. Aufgrund des physiologisch gegebenen geringen dielektrischen Kontrastes zwischen Drüsen- und Tumorgewebe kann durch den Einsatz von Kontrastmitteln, im Speziellen magnetischen Nanopartikeln, die Zuverlässigkeit einer Diagnose verbessert werden. Der Ansatz beruht darauf, dass funktionalisierte magnetische Nanopartikel in der Lage sind, sich selektiv im Tumorgewebe zu akkumulieren, nachdem diese intravenös verabreicht wurden. Unter der Bedingung, dass sich eine ausreichende Menge der Nanopartikel im Tumor angesammelt hat, können diese durch ein äußeres polarisierendes Magnetfeld moduliert werden. Aufgrund der Modulation ändert sich das Streuverhalten der magnetischen Nanopartikel, was wiederum zu einem sich ändernden Rückstreuverhalten führt. Diese Änderungen können mittels leistungsarmen elektromagnetischen Wellen detektiert werden. In dieser Arbeit wird die Detektierbarkeit und Bildgebung von magnetischen Nanopartikeln mittels Ultrabreitband-Sensorik im Mikrowellenfrequenzbereich in Hinblick auf die Brustkrebsdetektion betrachtet. Dabei werden zunächst verschiedene Einflussfaktoren, wie die Abhängigkeit der Masse der magnetischen Nanopartikel, die Magnetfeldstärke des äußeren Magnetfeldes sowie die Viskosität des Umgebungsmediums, in das die Nanopartikel eingebettet sind, auf die Detektierbarkeit der magnetischen Nanopartikel untersucht. Die Ergebnisse zeigen eine lineare Abhängigkeit zwischen dem gemessenen Radarsignal und der Masse der magnetischen Nanopartikel sowie einen nichtlinearen Zusammenhang zwischen der Antwort der magnetischen Nanopartikel und der Feldstärke des äußeren Magnetfeldes. Darüber hinaus konnten die magnetischen Nanopartikel für alle untersuchten Viskositäten erfolgreich detektiert werden. Basierend auf diesen Voruntersuchungen wird ein realistischer Messaufbau für die kontrastbasierte Brustkrebsbildgebung vorgestellt. Die Evaluierung des Messaufbaus erfolgt mittels Phantommessungen, wobei die verwendeten Phantommaterialien die dielektrischen Eigenschaften von biologischem Gewebe imitieren, um eine möglichst hohe Aussagekraft der Ergebnisse hinsichtlich eines praktischen Messszenarios zu erhalten. Dabei wird die Detektierbarkeit und Bildgebung der magnetischen Nanopartikel in Abhängigkeit der Tumortiefe analysiert. Die Ergebnisse zeigen, dass die magnetischen Nanopartikel erfolgreich detektiert werden können. Dabei hängt im dreidimensionalen Bild die Intensität des Messsignals, hervorgerufen durch die magnetischen Nanopartikel, von deren Position ab. Die Ursachen hierfür sind die pfadabhängige Dämpfung der elektromagnetischen Wellen, die inhomogene Ausleuchtung des Mediums mittels Mikrowellen, da eine gleichmäßige Anordnung der Antennen aufgrund der Magnetpole des Elektromagneten nicht möglich ist, sowie das inhomogene polarisierende Magnetfeld innerhalb des Untersuchungsmediums. In Bezug auf den letzten Aspekt wird das Magnetfeld im Untersuchungsbereich ausgemessen und ein Ansatz präsentiert, mit dem die Inhomogenität des Magnetfeldes kompensiert werden kann. Weiterhin wurden die Störeinflüsse des polarisierenden Magnetfeldes auf das Messsystem untersucht. In diesem Zusammenhang werden zwei verschiedene Modulationsarten (eine Modulation mit den zwei Zuständen AN/AUS und eine periodische Modulation) des äußeren polarisierenden Magnetfeldes analysiert. Es wird gezeigt, dass mit beiden Modulationen die magnetischen Nanopartikel bildgebend dargestellt werden können. Abschließend werden die Ergebnisse in Hinblick auf die Störeinflüsse sowie ein praktisches Anwendungsszenario diskutiert.Electromagnetic ultra-wideband sensing and imaging provide promising perspectives in various biomedical applications as these waves can penetrate biological tissue. The use of low-power and nonionizing electromagnetic waves in the microwave frequency range offers an examination method that is harmless to health. One of the challenges in the field of ultra-wideband microwave sensor technology is the extraction of diagnostically relevant information from the measurement data, since the complex wave propagation in tissue usually requires computationally intensive methods. This problem is simplified when the scattering properties of the object under observation change with time. Such a time variance of the scattering properties can be exploited by means of a differential measurement over a certain time interval. In this work, a differential approach using ultra-wideband sensing is considered for two medical applications. The measurement systems used in this work are based on the M-sequence technology developed at the Technische Universität Ilmenau. The first application relates to noninvasive temperature monitoring using ultra-wideband technology during hyperthermia treatment. Hyperthermia is a thermal therapy to support oncological treatments (e.g. chemotherapy or radiotherapy). During such a treatment, the tumor tissue is heated by 4 °C to 8 °C, whereby it is important that the temperature does not exceed the upper limit of 45 °C. In this context, differential ultra-wideband monitoring offers a promising technique for continuous and noninvasive temperature monitoring inside the body. The approach is based on the temperature-dependent dielectric properties of biological tissue. In this method, low power electromagnetic waves are emitted into the medium under investigation. These waves propagate according to the dielectric properties of tissue. If a target region (e.g. tumor) is heated, its dielectric properties will change, which leads to a changing scattering behavior of the electromagnetic wave. These changes can be detected in the measured reflection signals using ultra-wideband microwave technology. To evaluate the measured changes in the radar signal, it is necessary to know the temperature-dependent dielectric properties of tissue in the microwave frequency range. Due to the lack of knowledge of temperature-dependent dielectric properties of tissues over a wide microwave frequency range, the dielectric properties for liver, muscle, fat and blood in the temperature range between 30 °C and 50 °C from 500 MHz to 7 GHz are acquired in this work. For this purpose, a measurement setup for the temperature-dependent dielectric spectroscopy of tissue, tissue substitutes and fluids is presented. Furthermore, the main influences on measuring the temperature-dependent dielectric properties are analyzed. The measured data are modeled using a temperature-dependent Cole-Cole model in order to calculate the dielectric properties for arbitrary values in the investigated temperature and frequency range. In a further experiment, the noninvasive detection of temperature changes using ultra-wideband microwave technology is demonstrated in an experimental measurement setup. The results show that a temperature change of 1 °C results in differential signals that are detectable by means of ultra-wideband pseudo-noise sensing (M-sequence). The second application is dealing with contrast enhanced microwave breast cancer imaging. Due to the physiologically given low dielectric contrast between glandular and tumor tissue, the use of contrast agents, specifically magnetic nanoparticles, can improve the diagnostic reliability. The approach is based on the assumption that functionalized magnetic nanoparticles are able to selectively accumulate in tumor tissue after intravenous administration. Provided that a sufficient amount of nanoparticles has accumulated in the tumor, they can be modulated by an external polarizing magnetic field. Due to the modulation, the scattering behavior of the magnetic nanoparticles changes, which results a changing backscattering behavior. This change can be detected using low-power electromagnetic waves. In this work, the detectability and imaging of magnetic nanoparticles by means of ultra-wideband pseudo-noise sensing in the microwave frequency range is considered with respect to breast cancer detection. First, various influencing factors on the detectability of the magnetic nanoparticles are investigated, such as the mass of the magnetic nanoparticles, the magnetic field strength of the external polarizing magnetic field and the viscosity of the surrounding medium in which the nanoparticles are embedded. The results reveal a linear dependence between the measured radar signal and the mass of the magnetic nanoparticles as well as a nonlinear relationship between the response signal of the magnetic nanoparticles and the magnetic field intensity of the external magnetic field. Furthermore, the magnetic nanoparticles can be successfully detected in all investigated viscosities of the surrounding medium. Based on these preliminary investigations, a realistic measurement setup for contrast enhanced microwave breast cancer imaging is presented. The evaluation of the measurement setup is performed by phantom measurements, where the used phantom materials mimic the dielectric properties of biological tissue to obtain significance of the results with respect to a practical measurement scenario. In this context, the detectability and imaging of the magnetic nanoparticles are analyzed depending on the tumor position and penetration depth, respectively. The results show that the magnetic nanoparticles can be successfully detected. However, the magnetic poles of the electromagnet limit the space for the transmitting and receiving antennas, resulting in an inhomogeneous microwave illumination of the medium under test, which leads to a location-dependent magnetic nanoparticle response. Furthermore, the intensity of the response signal caused by the magnetic nanoparticles in the three-dimensional image depends on their position due to the path-dependent attenuation and the inhomogeneous magnetic field within the investigated medium. Regarding the last point, the external polarizing magnetic field is measured in the investigation area and an approach to compensate for the inhomogeneity of the magnetic field is presented. In addition, the disturbing influences of the polarizing magnetic field on the measurement setup are analyzed. In this context, two different modulation types (a two-state and a periodic modulation) of the external polarizing magnetic field are investigated. It is shown that both modulations can be used to image the magnetic nanoparticles. Finally, the results are discussed with respect to the spurious effects as well as a practical application scenario

Scenarios for the Strategic Planning of Technologies

Manufacturing based corporations often find themselves confronted with complexities of increased pressures to innovate in order to ensure their comparative market positions. In order to react to various exogenous changes corporations need to develop strategies that match their manufacturing resources as well as products with the markets requirements. Technology scenarios represent a holistic approach for managing innovation processes and technologies efficiently. A multidimensional requirement catalogue for specific product- market- combinations represents the fundamental building block for the ranking of particular material- components and technologies. The following analysis through evolutionary algorithms for compatibility between and amongst them provides the necessary information about their suitability. The resulting scenarios and roadmap and a regular monitoring process are prerequisite for the managerial decision making process and the implementation technology strategies.Manufacturing based corporations often find themselves confronted with complexities of increased pressures to innovate in order to ensure their comparative market positions. In order to react to various exogenous changes corporations need to develop strategies that match their manufacturing resources as well as products with the markets requirements. Technology scenarios represent a holistic approach for managing innovation processes and technologies efficiently. A multidimensional requirement catalogue for specific product- market- combinations represents the fundamental building block for the ranking of particular material- components and technologies. The following analysis through evolutionary algorithms for compatibility between and amongst them provides the necessary information about their suitability. The resulting scenarios and roadmap and a regular monitoring process are prerequisite for the managerial decision making process and the implementation technology strategies.Manufacturing based corporations often find themselves confronted with complexities of increased pressures to innovate in order to ensure their comparative market positions. In order to react to various exogenous changes corporations need to develop strategies that match their manufacturing resources as well as products with the markets requirements. Technology scenarios represent a holistic approach for managing innovation processes and technologies efficiently. A multidimensional requirement catalogue for specific product- market- combinations represents the fundamental building block for the ranking of particular material- components and technologies. The following analysis through evolutionary algorithms for compatibility between and amongst them provides the necessary information about their suitability. The resulting scenarios and roadmap and a regular monitoring process are prerequisite for the managerial decision making process and the implementation technology strategies

Quantitative interpretation of UWB radar images for non-invasive tissue temperature estimation during hyperthermia

The knowledge of temperature distribution inside the tissue to be treated is essential for patient safety, workflow and clinical outcomes of thermal therapies. Microwave imaging represents a promising approach for non-invasive tissue temperature monitoring during hyperthermia treatment. In the present paper, a methodology for quantitative non-invasive tissue temperature estimation based on ultra-wideband (UWB) radar imaging in the microwave frequency range is described. The capabilities of the proposed method are demonstrated by experiments with liquid phantoms and three-dimensional (3D) Delay-and-Sum beamforming algorithms. The results of our investigation show that the methodology can be applied for detection and estimation of the temperature induced dielectric properties change

MNP-enhanced microwave medical imaging by means of pseudo-noise sensing

Magnetic nanoparticles have been investigated for microwave imaging over the last decade. The use of functionalized magnetic nanoparticles, which are able to accumulate selectively within tumorous tissue, can increase the diagnostic reliability. This paper deals with the detecting and imaging of magnetic nanoparticles by means of ultra-wideband microwave sensing via pseudo-noise technology. The investigations were based on phantom measurements. In the first experiment, we analyzed the detectability of magnetic nanoparticles depending on the magnetic field intensity of the polarizing magnetic field, as well as the viscosity of the target and the surrounding medium in which the particles were embedded, respectively. The results show a nonlinear behavior of the magnetic nanoparticle response depending on the magnetic field intensity for magnetic nanoparticles diluted in distilled water and for magnetic nanoparticles embedded in a solid medium. Furthermore, the maximum amplitude of the magnetic nanoparticles responses varies for the different surrounding materials of the magnetic nanoparticles. In the second experiment, we investigated the influence of the target position on the three-dimensional imaging of the magnetic nanoparticles in a realistic measurement setup for breast cancer imaging. The results show that the magnetic nanoparticles can be detected successfully. However, the intensity of the particles in the image depends on its position due to the path-dependent attenuation, the inhomogeneous microwave illumination of the breast, and the inhomogeneity of the magnetic field. Regarding the last point, we present an approach to compensate for the inhomogeneity of the magnetic field by computing a position-dependent correction factor based on the measured magnetic field intensity and the magnetic susceptibility of the magnetic particles. Moreover, the results indicate an influence of the polarizing magnetic field on the measured ultra-wideband signals even without magnetic nanoparticles. Such a disturbing influence of the polarizing magnetic field on the measurements should be reduced for a robust magnetic nanoparticles detection. Therefore, we analyzed the two-state (ON/OFF) and the sinusoidal modulation of the external magnetic field concerning the detectability of the magnetic nanoparticles with respect to these spurious effects, as well as their practical application

Preliminary investigations of magnetic modulated nanoparticles for microwave breast cancer detection

This paper investigates the potential of magnetic modulated iron oxide nanoparticles in terms of a contrast enhancement for Ultra-wideband (UWB) breast imaging. The work is motivated by the low dielectric contrast between tumor and normal glandular/fibroconnective tissue. The influence of an external polarizing magnetic field on pure and coated magnetite nanoparticles is investigated in this contribution. Measurements were conducted using M-sequence UWB technology and an oil-gelatin phantom. It is shown that a coating, which is necessary for clinical use, results in a lower signal response, and thus leads to a lower detectability of magnetic modulated nanoparticles

Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry

Transabdominal fetal pulse oximetry is a method to monitor the oxygen supply of the unborn child non-invasively. Due to the measurement setup, the received signal of the detector is composed of photons coding purely maternal and photons coding mixed fetal-maternal information. To analyze the wellbeing of the fetus, the fetal signal is extracted from the mixed component. In this paper we assess source-detector configurations, such that the mixed fetal-maternal components of the acquired signals are maximized. Monte-Carlo method is used to simulate light propagation and photon distribution in tissue. We use a plane layer and a spherical layer geometry to model the abdomen of a pregnant woman. From the simulations we extracted the fluence at the detector side for several source-detector distances and analyzed the ratio of the mixed fluence component to total fluence. Our simulations showed that the power of the mixed component depends on the source-detector distance as expected. Further we were able to visualize hot spot areas in the spherical layer model where the mixed fluence ratio reaches the highest level. The results are of high importance for sensor design considering signal composition and quality for non-invasive fetal pulse oximetry

Stand zur IT-Sicherheit deutscher Stromnetzbetreiber : technischer Bericht

Innerhalb des Forschungsprojektes „Sichere Informationsnetze bei kleinen und mittleren Energieversorgern“ (SIDATE) wurde eine Umfrage zum Stand der IT-Sicherheit bei deutschen Stromnetzbetreibern durchgeführt. Das Projekt selbst beschäftigt sich mit der Informations- Sicherheit bei kleinen und mittleren Energieversorgern. Zur Durchführung der Umfrage wurden alle 881 im August 2016 bei der Bundesnetzagentur gelisteten Betreiber angeschrieben. In dem Umfragezeitraum vom 1. September 2016 bis zum 15. Oktober 2016 antworten 61 (6.9%) der Betreiber. Der Fragebogen fokussiert die Umsetzung der rechtlichen Anforderungen und die Implementierung eines Informationssicherheitsmanagementsystems (ISMS). Weiterhin wurden Fragen zu dem Leitsystem, Netzaufbau, Prozessen, organisatorischen Strukturen und der Büro-IT gestellt

Hardware dependencies of GPU-accelerated beamformer performances for microwave breast cancer detection

UWB microwave imaging has proven to be a promising technique for early-stage breast cancer detection. The extensive image reconstruction time can be accelerated by parallelizing the execution of the underlying beamforming algorithms. However, the efficiency of the parallelization will most likely depend on the grade of parallelism of the imaging algorithm and of the utilized hardware. This paper investigates the dependencies of two different beamforming algorithms on multiple hardware specification of several graphics boards. The parallel implementation is realized by using NVIDIA’s CUDA. Three conclusions are drawn about the behavior of the parallel implementation and how to efficiently use the accessible hardware

Morpho-Functional 1H-MRI of the Lung in COPD: Short-Term Test-Retest Reliability

Purpose Non-invasive end-points for interventional trials and tailored treatment regimes in chronic obstructive pulmonary disease (COPD) for monitoring regionally different manifestations of lung disease instead of global assessment of lung function with spirometry would be valuable. Proton nuclear magnetic resonance imaging (1H-MRI) allows for a radiation-free assessment of regional structure and function. The aim of this study was to evaluate the short-term reproducibility of a comprehensive morpho-functional lungMRI protocol in COPD. Materials and Methods 20 prospectively enrolled COPD patients (GOLD I-IV) underwent 1H-MRI of the lung at 1.5T on two consecutive days, including sequences for morphology, 4D contrast-enhanced perfusion, and respiratory mechanics. Image quality and COPD-related morphological and functional changes were evaluated in consensus by three chest radiologists using a dedicated MRI-based visual scoring system. Test-retest reliability was calculated per each individual lung lobe for the extent of large airway (bronchiectasis, wall thickening, mucus plugging) and small airway abnormalities (tree in bud, peripheral bronchiectasis, mucus plugging),consolidations, nodules, parenchymal defects and perfusion defects. The presence of tracheal narrowing, dystelectasis, pleural effusion, pulmonary trunk ectasia, right ventricular enlargement and, finally, motion patterns of diaphragma and chest wall were addressed. Results Median global scores [10(Q1:8.00;Q3:16.00) vs. 11(Q1:6.00;Q3:15.00)] as well as category subscores were similar between both timepoints, and kappa statistics indicated "almost perfect" global agreement (kappa = 0.86, 95% CI = 0.81-0.91). Most subscores showed at least "substantial" agreement of MRI1 and MRI2 (kappa = 0.64-1.00),whereas the agreement for the diagnosis of dystelectasis/effusion (kappa = 0.42, 95% CI = 0.00-0.93) was "moderate" and of tracheal abnormalities (kappa = 0.21, 95% CI = 0.00-0.75) "fair". Most MRI acquisitions showed at least diagnostic quality at MRI1 (276 of 278) and MRI2 (259 of 264). Conclusion Morpho-functional 1H-MRI can be obtained with reproducible image quality and high short-term test-retest reliability for COPD-related morphological and functional changes of the lung. This underlines its potential value for the monitoring of regional lung characteristics in COPD trials

Functional Lung MRI in Chronic Obstructive Pulmonary Disease: Comparison of T1 Mapping, Oxygen-Enhanced T1 Mapping and Dynamic Contrast Enhanced Perfusion

Purpose Monitoring of regional lung function in interventional COPD trials requires alternative end-points beyond global parameters such as FEV1. T1 relaxation times of the lung might allow to draw conclusions on tissue composition, blood volume and oxygen fraction. The aim of this study was to evaluate the potential value of lung Magnetic resonance imaging (MRI) with native and oxygen-enhanced T1 mapping for the assessment of COPD patients in comparison with contrast enhanced perfusion MRI. Materials and Methods 20 COPD patients (GOLD I-IV) underwent a coronal 2-dimensional inversion recovery snapshot flash sequence (8 slices/lung) at room air and during inhalation of pure oxygen, as well as dynamic contrast-enhanced first-pass perfusion imaging. Regional distribution of T1 at room air (T1), oxygen-induced T1 shortening (Delta T1) and peak enhancement were rated by 2 chest radiologists in consensus using a semi-quantitative 3-point scale in a zone-based approach. Results Abnormal T1 and Delta T1 were highly prevalent in the patient cohort. T1 and Delta T1 correlated positively with perfusion abnormalities (r = 0.81 and r = 0.80;p&0.001), and with each other (r = 0.80;p< 0.001). In GOLD stages I and II Delta T1 was normal in 16/29 lung zones with mildly abnormal perfusion (15/16 with abnormal T1). The extent of T1 (r = 0.45;p< 0.05), T1 (r = 0.52;p< 0.05) and perfusion abnormalities (r = 0.52;p< 0.05) showed a moderate correlation with GOLD stage. Conclusion Native and oxygen-enhanced T1 mapping correlated with lung perfusion deficits and severity of COPD. Under the assumption that T1 at room air correlates with the regional pulmonary blood pool and that oxygen-enhanced T1 reflects lung ventilation, both techniques in combination are principally suitable to characterize ventilation-perfusion imbalance. This appears valuable for the assessment of regional lung characteristics in COPD trials without administration of i. v. contrast