TY - THES A1 - Hoffmann, Jan Vincent T1 - Small-animal SPECT with Two Stationary Detectors: Performance Evaluation and Image Quality Assessment of Multi-pinhole Collimators T1 - Kleintier-SPECT mit Zwei Stationären Detektoren: Leistungsbewertung und Bildqualitätsanalyse von Multipinhole-Kollimatoren N2 - SPECT as a representative of molecular imaging allows visualization of metabolic processes in vivo. In clinical practice, single photon emission imaging is an established modality for myocardial perfusion imaging or the diagnosis of adrenal or neuroendocrine tumors, to name a few. With technical advances in scanner design and data processing leading to improved spatial resolution and image quality, SPECT has become a serious contender in small animal preclinical imaging. With multi-pinhole collimation, submillimeter spatial resolutions are achieved without limiting sensitivity, which has led to a significant increase of interest in SPECT for preclinical research in recent years. In this dissertation, the potential of a two-detector system through an analysis of three dedicated mouse collimators with multi-pinhole configurations was demonstrated. For this, sensitivity, spatial resolution, and uniformity as key parameters were determined. In the second part of the present work, an evaluation of the image quality at different activity concentrations to allow prediction of the system performance related to in vivo studies was performed. Therefore, a visual evaluation, as well as a calculation of the contrastto-noise ratio, was performed using mini Derenzo phantoms for the respective three mouse collimators. To better classify the results, the study was extended by a comparison with the predecessor system. Due to the absence of the third bottom detector, sensitivity and uniformity are slightly compromised. All three collimators were able to achieve a spatial resolution in the submillimeter range, XUHR-M offers a peak resolution of up to 0.35 mm. In terms of resolution, both evaluated systems performed on an equal level. Visual assessment of image quality indicates a slight advantage of the new two-detector system, and the contrast-to-noise ratio seems to benefit from the improved SROSEM algorithm. However, the differences between the two systems are marginal. The U-SPECT5/CT E-Class is proven to be state-of-the-art for small animal imaging and is a powerful instrument for preclinical molecular imaging research. Improvements in system design compensate well for the reduction in the detection area, allowing excellent imaging even with low activity concentrations. N2 - SPECT als Vertreter der molekularen Bildgebung ermöglicht die Visualisierung von Stoffwechselprozessen in vivo. In der klinischen Praxis ist die Einzelphotonen-Emissions-Bildgebung eine etablierte Modalität für die Myokard-Perfusions-Bildgebung oder die Diagnose von Nebennieren- oder neuroendokrinen Tumoren, um nur einige Beispiele zu nennen. Mit den technischen Fortschritten bei der Konstruktion von Scannern und der Datenverarbeitung, die zu einer verbesserten räumlichen Auflösung und Bildqualität führen, ist SPECT zu einem ernstzunehmenden Mitbewerber in der präklinischen Bildgebung von Kleintieren geworden. Unter der Verwendung von Multipinhole-Kollimatoren lassen sich Ortsauflösungen von unter einem Millimeter erzielen, ohne die Sensitivität deutlich einzuschränken. Dies trug dazu bei, dass das Interesse an SPECT in der präklinischen Forschung in den letzten Jahren zugenommen hat. In dieser Dissertation wurde das Potenzial eines Zweidetektorsystems unter Verwendung von drei Multipinhole-Mauskollimatoren evaluiert. Zur Leistungsbewertung wurde Sensitivität, Ortsauflösung und Homogenität bestimmt. Im zweiten Teil dieser Arbeit wurde eine Analyse der Bildqualität mit verschiedenen Aktivitätskonzentrationen durchgeführt, um eine Vorhersage der Leistung des Systems in In-vivo-Studien zu ermöglichen. Dazu wurde eine visuelle Bewertung sowie eine Berechnung des Kontrast-zu-Rausch-Verhältnisses mit Mini-Derenzo-Phantomen für die entsprechenden drei Mauskollimatoren durchgeführt. Um die Ergebnisse besser einordnen zu können, wurde die Studie um einen Vergleich mit dem Vorgängersystem erweitert. Durch das Fehlen des dritten unteren Detektors sind Sensitivität und Homogenität leicht beeinträchtigt. Alle drei Kollimatoren konnten eine Ortsauflösung unter einem Millimeter erreichen, wobei XUHR-M die höchste Auflösung von bis zu 0.35 mm erreicht. Die beiden untersuchten Systeme sind hinsichtlich der Ortsauflösung gleichwertig. Die visuelle Bewertung der Bildqualität deutet auf einen leichten, jedoch nur marginalen Vorteil des neuen Zweidetektorsystems hin, und das Kontrast-zu-Rausch-Verhältnis scheint von dem verbesserten SROSEM-Algorithmus zu profitieren. Das U-SPECT5/CT E-Class ist nachweislich auf dem neuesten Stand der Technik für die Bildgebung bei Kleintieren und ein leistungsfähiges Instrument für die präklinische Forschung. Das System kompensiert die Reduktion der Detektionsfläche und ermöglicht eine hervorragende Bildgebung auch bei geringen Aktivitätskonzentrationen. KW - SPECT KW - small-animal SPECT KW - performance evaluation KW - multi-pinhole collimation Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-328195 ER - TY - THES A1 - Janßen, Jan Paul T1 - Capabilities of a multi-pinhole SPECT system with two stationary detectors for in vivo imaging in rodents T1 - Leistungsfähigkeit eines Multi-Pinhole SPECT-Systems mit zwei stationären Detektoren zur In-vivo-Bildgebung in Nagetiermodellen N2 - Molecular imaging of rats is of great importance for basic and translational research. As a powerful tool in nuclear medicine, SPECT can be used to visualize specific functional processes in the body, such as myocardial perfusion or bone metabolism. Typical applications in laboratory animals are imaging diagnostics or the development of new tracers for clinical use. Innovations have enabled resolutions of up to a quarter of a millimeter with acceptable sensitivity. These advances have recently led to significantly more interest in SPECT both clinically and preclinically. The objective of this thesis was to evaluate the performance of the new U-SPECT5/CT E-Class by MILabs with a dedicated ultra-high resolution multi-pinhole collimator for rats and its potential for in vivo imaging of rats. The unique features of the U-SPECT are the large stationary detectors and the new iterative reconstruction algorithm. In addition, compared to the conventional system, the "E-Class" uses only two detectors instead of three. First, the sensitivity, maximum resolution, and uniformity were determined as performance parameters. Thereafter, CNRs for different activity levels comparable to those of typical in vivo activities were examined. Finally, two example protocols were carried out for imaging with 99mTc-MIBI and 99mTc-HMDP in healthy rats to evaluate the in vivo capabilities. For this purpose, CNR calculations and an image quality assessment were performed. The focus was on image quality as a function of scan time and post-reconstruction filter across a wide range of realistically achievable in vivo conditions. Performance was reasonable compared to other systems in the literature, with a sensitivity of 567 cps/MBq, a maximum resolution of 1.20 mm, and a uniformity of 55.5%. At the lower activities, resolution in phantom studies decreased to ≥1.80 mm while maintaining good image quality. High-quality bone and myocardial perfusion SPECTs were obtained in rats with a resolution of ≥1.80 mm and ≥2.20 mm, respectively. Although limited sensitivity remains a weakness of SPECT, the U-SPECT5/CT E-Class with the UHR-RM collimator can achieve in vivo results of the highest standard despite the missing third detector. Currently, it is one of the best options for high-resolution radionuclide imaging in rats. N2 - Die molekulare Bildgebung bei Ratten hat einen hohen Stellenwert in der Grundlagenforschung und der translationale Forschung. Dabei ist SPECT ein leistungsfähiges Instrument zur Visualisierung spezifischer funktioneller Prozesse im Körper, wie z. B. der Herzmuskeldurchblutung oder des Knochenstoffwechsels. Typische Anwendungsbereiche an Labortieren sind die bildgebende Diagnostik im Rahmen von Studien oder die Entwicklung neuer Tracer für den klinischen Einsatz. Durch Innovationen wurden Auflösungen von bis zu einem Viertelmillimeter bei akzeptabler Empfindlichkeit erreichbar. Diese Fortschritte haben in letzter Zeit zu einem deutlich gestiegenen Interesse an SPECT sowohl im klinischen als auch im präklinischen Bereich geführt. Ziel dieser Arbeit war es, die Leistung des neuen U-SPECT5/CT E-Class von MILabs mit einem speziellen ultra-hochauflösenden Multi-Pinhole-Kollimator für Ratten und das Potenzial für die In-vivo-Bildgebung bei Ratten zu untersuchen. Dabei sind die Besonderheiten des U-SPECTs die großen stationären Detektoren und der neue iterative Rekonstruktionsalgorithmus. Außerdem verfügt die von uns verwendete „E-Klasse“ im Vergleich zum konventionellen System nur über zwei statt drei Detektoren. Zunächst wurden die Sensitivität, die maximale Ortsauflösung und die Homogenität als Leistungsparameter bestimmt. Anschließend wurde das Kontrast-Rausch-Verhältnis für verschiedene Aktivitätsniveaus, die mit denen typischer In-vivo-Studien vergleichbar sind, untersucht. Schließlich wurden zwei Beispielprotokolle für die Bildgebung mit 99mTc-MIBI und 99mTc-HMDP bei gesunden Ratten durchgeführt, um die In-vivo-Kapazitäten zu erfassen. Zur Bewertung wurden eine Kontrast-Rausch-Analyse und eine Bildqualitätsumfrage genutzt. Der Schwerpunkt lag dabei auf der Bildqualität in Abhängigkeit von der Scanzeit sowie dem Postrekonstruktionsfilters für ein breites Spektrum realistisch erreichbarer In-vivo-Bedingungen. Die Leistung war mit einer Sensitivität von 567 cps/MBq, einer maximalen Ortsauflösung von 1,20 mm und einer Homogenität von 55,5% mit anderen in der Literatur beschriebenen Systemen vergleichbar. Bei niedrigeren Aktivitäten verringerte sich die Auflösung in Phantomstudien auf ≥1,80 mm bei gleichbleibend guter Bildqualität. Es wurden hochqualitative Knochen- und Myokardperfusions-SPECTs mit einer Auflösung von ≥1,80 mm bzw. ≥2,20 mm bei Ratten erzielt. Obwohl die begrenzte Empfindlichkeit nach wie vor eine Schwäche der SPECT ist, kann das U-SPECT5/CT E-Class mit dem UHR-RM-Kollimator, trotz des fehlenden dritten Detektors, In-vivo-Ergebnisse auf höchstem Niveau erzielen. Es ist derzeit eine der besten Optionen für die hochauflösende Radionuklid-Bildgebung bei Ratten. KW - SPECT KW - Molekulare Bildgebung KW - Rodents KW - Image Quality KW - SPECT/CT Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-328608 ER - TY - JOUR A1 - Leube, Julian A1 - Gustafsson, Johan A1 - Lassmann, Michael A1 - Salas-Ramirez, Maikol A1 - Tran-Gia, Johannes T1 - Analysis of a deep learning-based method for generation of SPECT projections based on a large Monte Carlo simulated dataset JF - EJNMMI Physics N2 - Background In recent years, a lot of effort has been put in the enhancement of medical imaging using artificial intelligence. However, limited patient data in combination with the unavailability of a ground truth often pose a challenge to a systematic validation of such methodologies. The goal of this work was to investigate a recently proposed method for an artificial intelligence-based generation of synthetic SPECT projections, for acceleration of the image acquisition process based on a large dataset of realistic SPECT simulations. Methods A database of 10,000 SPECT projection datasets of heterogeneous activity distributions of randomly placed random shapes was simulated for a clinical SPECT/CT system using the SIMIND Monte Carlo program. Synthetic projections at fixed angular increments from a set of input projections at evenly distributed angles were generated by different u-shaped convolutional neural networks (u-nets). These u-nets differed in noise realization used for the training data, number of input projections, projection angle increment, and number of training/validation datasets. Synthetic projections were generated for 500 test projection datasets for each u-net, and a quantitative analysis was performed using statistical hypothesis tests based on structural similarity index measure and normalized root-mean-squared error. Additional simulations with varying detector orbits were performed on a subset of the dataset to study the effect of the detector orbit on the performance of the methodology. For verification of the results, the u-nets were applied to Jaszczak and NEMA physical phantom data obtained on a clinical SPECT/CT system. Results No statistically significant differences were observed between u-nets trained with different noise realizations. In contrast, a statistically significant deterioration was found for training with a small subset (400 datasets) of the 10,000 simulated projection datasets in comparison with using a large subset (9500 datasets) for training. A good agreement between synthetic (i.e., u-net generated) and simulated projections before adding noise demonstrates a denoising effect. Finally, the physical phantom measurements show that our findings also apply for projections measured on a clinical SPECT/CT system. Conclusion Our study shows the large potential of u-nets for accelerating SPECT/CT imaging. In addition, our analysis numerically reveals a denoising effect when generating synthetic projections with a u-net. Clinically interesting, the methodology has proven robust against camera orbit deviations in a clinically realistic range. Lastly, we found that a small number of training samples (e.g., ~ 400 datasets) may not be sufficient for reliable generalization of the u-net. KW - 177Lu KW - Monte Carlo KW - SPECT KW - Deep learning KW - Denoising Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300697 SN - 2197-7364 VL - 9 ER - TY - JOUR A1 - Hoffmann, Jan V. A1 - Janssen, Jan P. A1 - Kanno, Takayuki A1 - Shibutani, Takayuki A1 - Onoguchi, Masahisa A1 - Lapa, Constantin A1 - Grunz, Jan-Peter A1 - Buck, Andreas K. A1 - Higuchi, Takahiro T1 - Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging JF - EJNMMI Physics N2 - Background Small-animal single-photon emission computed tomography (SPECT) systems with multi-pinhole collimation and large stationary detectors have advantages compared to systems with moving small detectors. These systems benefit from less labour-intensive maintenance and quality control as fewer prone parts are moving, higher accuracy for focused scans and maintaining high resolution with increased sensitivity due to focused pinholes on the field of view. This study aims to investigate the performance of a novel ultra-high-resolution scanner with two-detector configuration (U-SPECT5-E) and to compare its image quality to a conventional micro-SPECT system with three stationary detectors (U-SPECT\(^+\)). Methods The new U-SPECT5-E with two stationary detectors was used for acquiring data with \(^{99m}\)Tc-filled point source, hot-rod and uniformity phantoms to analyse sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR). Three dedicated multi-pinhole mouse collimators with 75 pinholes each and 0.25-, 0.60- and 1.00-mm pinholes for extra ultra-high resolution (XUHR-M), general-purpose (GP-M) and ultra-high sensitivity (UHS-M) imaging were examined. For CNR analysis, four different activity ranges representing low- and high-count settings were investigated for all three collimators. The experiments for the performance assessment were repeated with the same GP-M collimator in the three-detector U-SPECT\(^+\) for comparison. Results Peak sensitivity was 237 cps/MBq (XUHR-M), 847 cps/MBq (GP-M), 2054 cps/MBq (UHS-M) for U-SPECT5-E and 1710 cps/MBq (GP-M) for U-SPECT\(^+\). In the visually analysed sections of the reconstructed mini Derenzo phantoms, rods as small as 0.35 mm (XUHR-M), 0.50 mm (GP-M) for the two-detector as well as the three-detector SPECT and 0.75 mm (UHS-M) were resolved. Uniformity for maximum resolution recorded 40.7% (XUHR-M), 29.1% (GP-M, U-SPECT5-E), 16.3% (GP-M, U-SPECT\(^+\)) and 23.0% (UHS-M), respectively. UHS-M reached highest CNR values for low-count images; for rods smaller than 0.45 mm, acceptable CNR was only achieved by XUHR-M. GP-M was superior for imaging rods sized from 0.60 to 1.50 mm for intermediate activity concentrations. U-SPECT5-E and U-SPECT+ both provided comparable CNR. Conclusions While uniformity and sensitivity are negatively affected by the absence of a third detector, the investigated U-SPECT5-E system with two stationary detectors delivers excellent spatial resolution and CNR comparable to the performance of an established three-detector-setup. KW - small-animal imaging KW - SPECT KW - mouse KW - ollimator KW - post-reconstruction filtering Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230361 VL - 7 ER - TY - JOUR A1 - Buck, Andreas A1 - Decristoforo, Clemens T1 - Highlights lecture EANM 2015: the search for nuclear medicine's superheroes JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - The EANM 2015 Annual Congress, held from October 10th to 14th in Hamburg, Germany, was outstanding in many respects. With 5550 participants, this was by far the largest European congress concerning nuclear medicine. More than 1750 scientific presentations were submitted, with more than 250 abstracts from young scientists, indicating that the future success of our discipline is fuelled by a high number of young individuals becoming involved in a multitude of scientific activities. Significant improvements have been made in molecular imaging of cancer, particularly in prostate cancer. PSMA-directed PET/CT appears to become a new gold standard for staging and restaging purposes. Novel tumour specific compounds have shown their potential for target identification also in other solid neoplasms and further our understanding of tumour biology and heterogeneity. In addition, a variety of nuclear imaging techniques guiding surgical interventions have been introduced. A particular focus of the congress was put on targeted, radionuclide based therapies. Novel theranostic concepts addressing also tumour entities with high incidence rates such as prostate cancer, melanoma, and lymphoma, have shown effective anti-tumour activity. Strategies have been presented to improve further already established therapeutic regimens such as somatostatin receptor based radio receptor therapy for treating advanced neuroendocrine tumours. Significant contributions were presented also in the neurosciences track. An increasing number of target structures of high interest in neurology and psychiatry are now available for PET and SPECT imaging, facilitating specific imaging of different subtypes of dementia and movement disorders as well as neuroinflammation. Major contributions in the cardiovascular track focused on further optimization of cardiac perfusion imaging by reducing radiation exposure, reducing scanning time, and improving motion correction. Besides coronary artery disease, many contributions focused on cardiac inflammation, cardiac sarcoidosis, and specific imaging of large vessel vasculitis. The physics and instrumentation track included many highlights such as novel, high resolution scanners. The most noteworthy news and developments of this meeting were summarized in the highlights lecture. Only 55 scientific contributions were mentioned, and hence they represent only a brief summary, which is outlined in this article. For a more detailed view, all presentations can be accessed by the online version of the European Journal of Nuclear Medicine and Molecular Imaging (Volume 42, Supplement 1). KW - Conjugate arc therapy KW - Phase-II KW - 18F-FDG PET/CT KW - Highlights Lecture KW - Molecular Imaging KW - Prostate-cancer KW - Radionuclide therapy KW - Myocardial perfusion KW - Preclinical evaluation KW - Targeted therapy KW - Thyroid cancer KW - SPECT KW - 2015 KW - EANM KW - Hamburg KW - Physics and instrumentation KW - Radiopharmacy KW - Oncology KW - Radionuclide Therapy KW - Cardiology KW - Neurosciences Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187613 VL - 43 IS - 10 ER - TY - THES A1 - Küsters, Sebastian T1 - Darstellung des nikotinergen Acetylcholinrezeptors bei Patienten mit idiopathischem Parkinson-Syndrom und Levodopa-induzierter Dyskinesie T1 - Nicotinic acetylcholine receptors in patients with idiopathic Parkinson's disease and levodopa-induced dyskinesia N2 - Ziel der Studie war ein Zusammenhang zwischen cholinerger Innervation in den Basalganglien mit Levodopa-induzierter Dyskinesie darzustellen. 26 Patienten mit idiopatischem Parkinson-Syndrom ohne Demenz und Depression wurden in zwei Gruppen mit und ohne Dyskinesie eingeteilt. Es wurde nach klinischer Untersuchung eine SPECT-Bildgebung mit 5-[123I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5IA) durchgeführt und anschließend die Ergebnisse in Zusammenschau mit den klinischen Daten und mit den Ergebnissen der SPECT mit [123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane (FP-CIT) bewertet. Dyskinetische Patienten hatten eine höhere Dichte an nikotinergen Acetylcholinrezeptoren im Nucleus caudatus, hauptsächlich der Halbseite mit stärkerer dopaminerger Degeneration. Dies stützt die Hypothese, dass sich die Dyskinesie nach Levodopa-Therapie aufgrund einer verstärkten cholinergen Modulation im stärker degenerierten Striatum entwickelt. N2 - Objective: To explore cholinergic innervation in the basal ganglia in relation to levodopa-induced dyskinesia in patients with Parkinson’s disease. Methods: A total of 26 patients with PD without dementia and depression were divided into two matched groups (dyskinetic and nondyskinetic). We acquired SPECT scan with 5-[123I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine. We then analyzed binding potentials at basal ganglia structures and correlations with clinical variables and [123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane SPECT. Results: Dyskinetic subjects showed higher density of nicotinic acetylcholine receptors in the caudate nucleus, predominant in the hemisphere with lower dopamine transporter density. Conclusion: Our findings support the hypothesis that the expression of dyskinesia following repeated levodopa exposure may result from enhanced cholinergic neuronal excitability in a dopaminergic-depleted striatum. KW - Parkinson-Krankheit KW - Dyskinesie KW - Bewegungsstörung KW - Acetylcholinrezeptor KW - SPECT KW - nACh-Rezeptor Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-178740 ER - TY - JOUR A1 - Werner, Rudolf A. A1 - Marcus, Charles A1 - Sheikhbahaei, Sara A1 - Solnes, Lilja B. A1 - Leal, Jeffrey P. A1 - Du, Yong A1 - Rowe, Steven P. A1 - Higuchi, Takahiro A1 - Buck, Andreas K. A1 - Lapa, Constantin A1 - Javadi, Mehrbod S. T1 - Visual and Semiquantitative Accuracy in Clinical Baseline 123I-Ioflupane SPECT/CT Imaging JF - Clinical Nuclear Medicine N2 - PURPOSE: We aimed to (a) elucidate the concordance of visual assessment of an initial I-ioflupane scan by a human interpreter with comparison to results using a fully automatic semiquantitative method and (b) to assess the accuracy compared to follow-up (f/u) diagnosis established by movement disorder specialists. METHODS: An initial I-ioflupane scan was performed in 382 patients with clinically uncertain Parkinsonian syndrome. An experienced reader performed a visual evaluation of all scans independently. The findings of the visual read were compared with semiquantitative evaluation. In addition, available f/u clinical diagnosis (serving as a reference standard) was compared with results of the human read and the software. RESULTS: When comparing the semiquantitative method with the visual assessment, discordance could be found in 25 (6.5%) of 382 of the cases for the experienced reader (ĸ = 0.868). The human observer indicated region of interest misalignment as the main reason for discordance. With neurology f/u serving as reference, the results of the reader revealed a slightly higher accuracy rate (87.7%, ĸ = 0.75) compared to semiquantification (86.2%, ĸ = 0.719, P < 0.001, respectively). No significant difference in the diagnostic performance of the visual read versus software-based assessment was found. CONCLUSIONS: In comparison with a fully automatic semiquantitative method in I-ioflupane interpretation, human assessment obtained an almost perfect agreement rate. However, compared to clinical established diagnosis serving as a reference, visual read seemed to be slightly more accurate as a solely software-based quantitative assessment. KW - Single-Photon-Emissions-Computertomographie KW - SPECT KW - Parkinson’s disease KW - Parkinsonism KW - DaTscan KW - 123I-Ioflupane KW - SPECT KW - SPECT/CT Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-168181 SN - 1536-0229 VL - 44 IS - 1 ER - TY - JOUR A1 - Chen, Xinyu A1 - Werner, Rudolf A. A1 - Javadi, Mehrbod S. A1 - Maya, Yoshifumi A1 - Decker, Michael A1 - Lapa, Constantin A1 - Herrmann, Ken A1 - Higuchi, Takahiro T1 - Radionuclide imaging of neurohormonal system of the heart JF - Theranostics N2 - Heart failure is one of the growing causes of death especially in developed countries due to longer life expectancy. Although many pharmacological and instrumental therapeutic approaches have been introduced for prevention and treatment of heart failure, there are still limitations and challenges. Nuclear cardiology has experienced rapid growth in the last few decades, in particular the application of single photon emission computed tomography (SPECT) and positron emission tomography (PET), which allow non-invasive functional assessment of cardiac condition including neurohormonal systems involved in heart failure; its application has dramatically improved the capacity for fundamental research and clinical diagnosis. In this article, we review the current status of applying radionuclide technology in non-invasive imaging of neurohormonal system in the heart, especially focusing on the tracers that are currently available. A short discussion about disadvantages and perspectives is also included. KW - SPECT KW - radiotracer KW - heart failure KW - cardiac neurohormonal system KW - nuclear cardiology KW - PET Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149205 VL - 5 IS - 6 ER - TY - JOUR A1 - Werner, Rudolf A. A1 - Chen, Xinyu A1 - Rowe, Steven P. A1 - Lapa, Constantin A1 - Javadi, Mehrbod S. A1 - Higuchi, Takahiro T1 - Moving into the Next Era of PET Myocardial Perfusion Imaging - Introduction of Novel \(^{18}\)F-labeled Tracers JF - The International Journal of Cardiovascular Imaging N2 - The heart failure (HF) epidemic continues to rise with coronary artery disease (CAD) as one of its main causes. Novel concepts for risk stratification to guide the referring cardiologist towards revascularization procedures are of significant value. Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) agents has demonstrated high accuracy for the detection of clinically relevant stenoses. With positron emission tomography (PET) becoming more widely available, mainly due to its diagnostic performance in oncology, perfusion imaging with that modality is more practical than in the past and overcomes existing limitations of SPECT MPI. Advantages of PET include more reliable quantification of absolute myocardial blood flow, the routine use of computed tomography for attenuation correction, a higher spatiotemporal resolution and a higher count sensitivity. Current PET radiotracers such as rubidium-82 (half-life, 76 sec), oxygen-15 water (2 min) or nitrogen-13 ammonia (10 min) are labeled with radionuclides with very short half-lives, necessitating that stress imaging is performed under pharmacological vasodilator stress instead of exercise testing. However, with the introduction of novel 18F-labeled MPI PET radiotracers (half-life, 110 min), the intrinsic advantages of PET can be combined with exercise testing. Additional advantages of those radiotracers include, but are not limited to: potentially improved cost-effectiveness due to the use of pre-existing delivery systems and superior imaging qualities, mainly due to the shortest positron range among available PET MPI probes. In the present review, widely used PET MPI radiotracers will be reviewed and potential novel 18F-labeled perfusion radiotracers will be discussed. KW - heart failure with mid-range ejection fraction KW - Positronenemissionstomografie KW - coronary artery disease KW - precision medicine KW - positron emission tomography KW - PET KW - SPECT KW - myocardial perfusion imaging KW - MPI KW - 18F-flurpiridaz KW - 18FFBnTP KW - HFmrEF Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169134 SN - 1569-5794 ER - TY - JOUR A1 - Werner, Rudolf A. T1 - Editorial: Cardiac Innervation Imaging as a Risk Stratification Tool for Potential Device Therapy Candidates JF - Journal of Nuclear Cardiology N2 - As a scintigraphic approach evaluating cardiac nerve integrity, \(^{123}\)I-metaiodobenzylguanidine (123I-mIBG) has been recently Food and Drug Administration approved. A great deal of progress has been made by the prospective ADMIRE-HF trial, which primarily demonstrated the association of denervated myocardium assessed by \(^{123}\)I-mIBG and cardiac events. However, apart from risk stratification, myocardial nerve function evaluated by molecular imaging should also be expanded to other clinical contexts, in particular to guide the referring cardiologist in selecting appropriate candidates for specific therapeutic interventions. In the present issue of the Journal of Nuclear Cardiology, the use of 123I-mIBG for identifying cardiomyopathy patients, which would most likely not benefit from ICD due low risk of arrhythmias, is described. If we aim to deliver on the promise of cardiac innervation imaging as a powerful tool for risk stratification in a manner similar to nuclear oncology, studies such as the one reviewed here may imply an important step to lay the proper groundwork for a more widespread adoption in clinical practice. KW - SPECT KW - SPECT KW - myocardial nerve KW - 123I-metaiodobenzylguanidine KW - 123I-mIBG KW - cardiac nerve KW - ICD KW - arrhythmia KW - cardiac innervation imaging Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-168465 UR - https://rdcu.be/970i SN - 1071-3581 N1 - SharedIt-Link zur Publikation: https://rdcu.be/970i N1 - This is a post-peer-review, pre-copyedit version of an article published in Journal of Nuclear Cardiology. The final authenticated version is available online at: http://dx.doi.org/10.1007/s12350-018-01475-0 ER - TY - CHAP A1 - Werner, Rudolf A. A1 - Marcus, Charles A1 - Sheikhbahaei, Sara A1 - Higuchi, Takahiro A1 - Solnes, Lilja B. A1 - Rowe, Steven P. A1 - Buck, Andreas K. A1 - Lapa, Constantin A1 - Javadi, Mehrbod S. T1 - The Impact of Ageing on Dopamine Transporter Imaging T2 - Journal of Nuclear Medicine N2 - No abstract available. KW - Parkinson-Krankheit KW - Parkinson KW - Parkinson Disease KW - DaTscan KW - Ioflupane KW - SPECT KW - molecular imaging KW - ageing Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-162213 UR - http://jnm.snmjournals.org/content/59/supplement_1/1646.abstract SN - 0161-5505 N1 - This research was originally published in JNM. Rudolf A. Werner, Charles Marcus, Sara Sheikhbahaei, Takahiro Higuchi, Lilja B. Solnes, Steven P. Rowe, Andreas K. Buck, Constantin Lapa, Mehrbod S. Javadi. The Impact of Ageing on Dopamine Transporter Imaging. J Nucl Med. May 1, 2018; vol. 59 no. supplement 1:1646. © SNMMI. VL - 59 IS - Supplement No 1 SP - 1646 ER - TY - CHAP A1 - Werner, Rudolf A. A1 - Marcus, Charles A1 - Sheikhbahaei, Sara A1 - Higuchi, Takahiro A1 - Solnes, Lilja B. A1 - Rowe, Steven P. A1 - Buck, Andreas K. A1 - Lapa, Constantin A1 - Javadi, Mehrbod S. T1 - Diagnostic Accuracy of Visual Assessment of an Initial DaT-Scan in Comparison to a Fully Automatic Semiquantitative Method T2 - Journal of Nuclear Medicine N2 - No abstract available. KW - Parkinson-Krankheit KW - SPECT KW - Parkinson KW - Parkinson Disease KW - DaTscan KW - Ioflupane KW - molecular imaging Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-162208 UR - http://jnm.snmjournals.org/content/59/supplement_1/626.abstract SN - 0161-5505 N1 - This research was originally published in JNM. Rudolf A. Werner, Charles Marcus, Sara Sheikhbahaei, Takahiro Higuchi, Lilja B. Solnes, Steven P. Rowe, Andreas K. Buck, Constantin Lapa, Mehrbod S. Javadi. Diagnostic Accuracy of Visual Assessment of an Initial DaT-Scan in Comparison to a Fully Automatic Semiquantitative Method. J Nucl Med. May 1, 2018; vol. 59 no. supplement 1:626. © SNMMI. VL - 59 IS - Supplement No. 1 SP - 626 ER - TY - THES A1 - Girardet, Fabian T1 - Der kardiale BOLD-Effekt und die Narbendarstellung per delayed enhancement in der Magnetresonanztomographie im Vergleich zu Myokardszintigraphie und Koronarangiographie T1 - The cardial BOLD effect and scar detection by delayed enhancement in MRI compared with myocardial scintigraphy and coronary angiography N2 - Eine Koronare Herzkrankheit wird derzeit primär im Herzkatheterlabor diagnostiziert oder aus-geschlossen. Werden bei der Untersuchung Stenosen festgestellt, muß von der Morphologie auf die Bedeutung für das versorgte Myokard geschlossen werden. Der Untersucher kann dabei im Herzkatheterlabor nur bedingt beurteilen, inwiefern die Durchblutung des Herzens auch tatsäch-lich eingeschränkt ist. Für den in diesem Fall notwendigen Ischämienachweis steht neben der Myokardszintigraphie mittlerweile auch die kardiale Magnetresonanztomographie zur Verfü-gung. In Vorarbeiten dieser Arbeitsgruppe war es gelungen, das körpereigene Kontrastmittel Hämog-lobin zur Abbildung von Anpassungsvorgängen in poststenotischen Myokardarealen zu nutzen. Bei hämodynamisch relevanter Stenosierung war eine Verkürzung der T2*-Zeit beobachtet worden, die auf eine erhöhte Konzentration des paramagnetischen Desoxyhämoglobin zurück-geführt wurde. Dieser Zusammenhang wird als blood oxygenation level dependent(BOLD)-Effekt bezeichnet. In vorliegender Arbeit wurde die Technik der kardialen T2*-Messung an einem größeren Kol-lektiv von 55 Patienten mit vermuteter oder bekannter KHK erprobt. Die Messungen von T2* wurden in Atemanhaltetechnik mit einer segmentierten Multigradientechosequenz unter Nativ-bedingungen durchgeführt. Als konkurrierendes Verfahren wurde bei allen Patienten die Myo-kardszintigraphie mit Tc99m-Sestamibi durchgeführt. Bei der Auswertung der MRT-Daten zeigte sich, dass 30% der gemessenen T2*-Zeiten zuvor festgelegten statistischen Kriterien nicht genügte und verworfen werden mußte. Für den Ver-gleich der MRT mit der Koronarangiographie als Referenzmethode wurde der kardiale Kurz-achsenschnitt auf midventrikulärer Ebene zu Segmenten von VW/HW und RIVA, RCX, RCA zusammengefasst. Von Segmenten, die deutlich kürzere T2*-Zeiten aufwiesen, als die übrigen Segmente, wurde angenommen, sie lägen im Stromgebiet stenosierter Koronargefäße. Der computergestützte Vergleich beider Verfahren mit der Referenzmethode zeigte, dass die MRT in dem auf VW/HW reduzierten Modell des Herzens gleichwertige Ergebnisse erzielte wie die Myokardszintigraphie (Übereinstimmung T2* 60,5% vs Myokardszintigraphie 52%). Vor dem Hintergrund mangelnder statistischer Signifikanz kann dies als Trend interpretiert werden. Eine weitere Differenzierung des Modells ergab, dass einzeln betrachtet auch die drei Stromgebiete der Koronararterien weitgehend in Übereinstimmung mit der Koronarangi-ographie beurteilt wurden (RIVA 57,9%, RCX 64,9%, RCA 65,8%). Insbesondere Patienten ohne hämodynamische Stenosierung waren gut an homogeneren Relaxationszeiten zu erkennen. Wie in Vorarbeiten gezeigt werden konnte, lässt sich die diagnostische Leistungsfähigkeit durch ein Stressprotokoll weiter verbessern, so dass die BOLD-Bildgebung ein viel versprechendes Verfahren der kardialen Ischämiediagnostik darstellt. Parallel wurde in vorliegender Arbeit der Narbennachweis per delayed enhancement (LE) mit der Myokardszintigraphie verglichen. Abgestorbenes Myokard wird kollagen umgebaut und verfügt danach über größere Zellzwischenräume als normaler Herzmuskel. Das vergrößerte Ver-teilungsvolumen und eine reduzierte Kapillardichte führen dazu, dass das applizierte Kontrast-mittel (Gadodiamide) von dort langsamer entfernt wird als in normalem Myokard. Werden die MRT-Bilder zeitlich verzögert (10-30min) aufgenommen, lässt sich auf diese Weise vernarbtes Herzgewebe an einem kürzeren T1 erkennen. Der Vergleich des Narbennachweises der Myokardszintigraphie mit dem LE zeigte eine hohe Übereinstimmung. Subendokardiales Narbengewebe wurde mit der MRT besser erfasst. BOLD und LE zeigen, dass die MRT in der Lage ist neben der makroskopischen Anatomie auch Anpassungsreaktionen der Mikrozirkulation sowie histologische Veränderungen abzubilden. In weiteren Studien sollte an selektierten Patientenkollektiven ermittelt werden, welchen Einfluss Begleiterkrankungen auf die Ausprägung des BOLD-Effektes haben. Neben Fortschritten in der diagnostischen Zuverlässigkeit könnte dies zu einem besseren Verständnis der Pathophysiologie kardialer Erkrankungen beitragen. Das delayed enhancement weist zuverlässig kardiales Narbengewebe nach und hat aufgrund höherer Auflösung und fehlender Strahlenbelastung deutliche Vorteile gegenüber der Myokard-szintigraphie. N2 - Coronary artery disease is being diagnosed or excluded primarily in the catheter laboratory. If stenoses are found, the investigator has to determine the relevance of the stenosis based on morphology alone. For a better further assessment cardiac MRI has become available as an alternative to myocardial szintigraphy. In previous studies this group had succeeded in using the body-own contrast agent hemoglobin to visualize altered microcirculation in poststenotic myocardium. Myocardium supplied by arteries with significant stenosis had shorter T2* relaxation time, which were attributed to an increased concentration of the paramagnetic desoxyhemoglobin. This relation is known as blood oxygenation level dependent (BOLD) effect. In this study the value of T2* for diagnosing coronary artery disease (CAD) was tested with 55 patients, who had known or suspected CAD. The measurements of T2 * were accomplished during breath hold with a segmented multi-gradient echo sequence on native conditions. As a competitive procedure all patients underwent myocardial szintigraphy with Tc99m-Sestamibi. During the evaluation it showed up that 30% of T2* data did not meet previously fixed statistic criteria and had to be rejected. For the comparison of MRI results with the coronary angiography as reference method the short axis slice on midventricular level was combined into segments of anterior/posterior wall and RIVA, RCX, RCA. Segments, which showed clearly shorter T2* as the remaining segments, where thought to represent poststenotic myocardium. The computer-assisted comparison of both procedures with the reference method showed that MRI in the simplified heart model obtained equivalent results as the myocardial scintigraphy (overall agreement T2 * 60.5% vs szintigraphy 52%). Due to the fact, that the results did not reach statistic significance, this can only be interpreted as a trend. A further differentiation of the heart model was judged to a large extent in accordance with coronary angiography (RIVA 57.9%, RCX 64.9%, RCA 65.8%). In particular patients without hemodynamic stenoses were recognized well by homogeneous relaxation times. As was shown in previous studies the diagnostic efficiency can be improved by adding a stress protocol. BOLD imaging represents a promising procedure in the field of evaluation of CAD. At the same time scar detection by delayed enhancement (LE) was compared with myocardial scintigraphy. Necrotic myocardium is converted into collagen and has larger cell gaps than normal heart muscle. The increased distribution volume and a reduced capillary density lead to the fact that the injected contrast agent (Gadodiamide) is removed more slowly than in normal myocardium. If MRI pictures were obtained 10-30 min after application of the contrast agent scarred myocardium was clearly recognized be shorter T1. Compared with myocardial scintigraphy delayed enhancement showed a high overall correspondence. Subendcardial scar tissue was better identified with MRI. BOLD and LE show that MRI can visualize apart from macroscopic anatomy also adjustment reactions of the microcirculation as well as histological changes. Further studies should determine at more selected patient collectives, which influence concomitant disease have on the development of the BOLD effect This could, apart from progress in the diagnostic reliability, contribute to a better understanding of pathophysiology of cardiac illnesses. Delayed enhancement identifies reliably scarred myocardium and has advantages due to higher resolution and missing radiation dose in opposite to myocardial scintigraphy. KW - BOLD-Effekt KW - T2* KW - Magnetresonanztomographie KW - late enhancement KW - SPECT KW - BOLD effect KW - T2* KW - magnetic resonance imaging (MRI) KW - late enhancement KW - SPECT Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-23266 ER - TY - THES A1 - Nowotny, Anja T1 - Vergleich der diagnostischen Wertigkeit der Dobutamin-Kontraststressechokardiographie und der Myokardszintigraphie mit der Referenzmethode Druckdrahtmessung zur Beurteilung mittelgradiger Koronarstenosen T1 - Comparison of pressure wire measurement, dobutamine contrast stress echocardiography and SPECT for the evaluation of intermediate coronary stenoses N2 - In der vorliegenden klinischen Studie untersuchten wir die diagnostische Genauigkeit zweier nicht invasiver Verfahren, nämlich des Nachweises der nativen und kontrastmittelverstärkten Stressechokardiographie sowie der Myokardszintigraphie bei visuell als mittelgradig eingeschätzten Koronarstenosen. Eingeschlossen wurden 48 Patienten mit einer angiographisch nachgewiesenen 50- 75% Lumenreduktion eines Herzkranzgefäßes. Die Untersuchungen wurden simultan mittels pharmakologischer Belastung (Dobutamin) durchgeführt und die Ergebnisse miteinander verglichen. Als Referenzmethode diente die Druckdrahtmessung, welche eine Objektivierung der hämodynamischen Relevanz besonders mittelgradiger Koronarstenosen durch die Ermittlung der fraktionellen Flussreserve als Quotienten aus post- und prästenotischem Druck direkt im betroffenen Koronargefäß ermöglicht. Der Schwerpunkt dieser Arbeit lag in der Analyse der Beurteilbarkeit und diagnostischen Wertigkeit von Dobutamin- Stressechokardiogrammen vor und nach Applikation von Kontrastmitteln der 2. Generation (Optison® bzw. Sonovue®). Die Interpretation aller Echokardiogramme erfolgte gemäß dem 16 Segmentmodell der American Society of Echocardiography. Die Endokarddelineation wurde sowohl in Ruhe als auch unter Belastung bewertet, wobei eine signifikante Verbesserung nach Injektion des Kontrastmittels erreicht wurde. Der Index steigerte sich insbesondere in den apikalen, anterioren und lateralen Segmenten, was für die klinische Praxis vor allem eine Verbesserung der Beurteilung der hämodynamischen Relevanz von Stenosen des Versorgungsgebietes von RIVA und RCX bedeutet. Die Segmente des RCA-Versorgungsgebietes waren bereits in der nativen Bildgebung ausreichend beurteilbar. Die Stressechokardiogramme wurden bezüglich der Wandbewegungsstörungen von zwei unabhängigen und erfahrenen Untersuchern ohne Kenntnis der Ergebnisse der anderen Ischämietests bzw. des Ergebnisses der Koronarangiographie und der Bestimmung der fraktionellen Flussreserve beurteilt. Die Nativuntersuchungen wurden gemäß den standardisierten Richtlinien von Hoffmann et al. interpretiert. Für die Bewertung der kontrastverstärkten Stressechokardiogramme wurde, sich an den Ergebnissen der Druckdrahtmessung orientierend, ein optimales Bewertungsmodell gesucht. Die größte diagnostische Genauigkeit ergab sich, wenn neu induzierte, gleich bleibende oder zunehmende Wandbewegungsstörungen in mindestens 2 direkt aneinander angrenzenden Segmenten als pathologisch gewertet wurde. Bei der Myokardszintigraphie wurden alle neuen und unter Belastung zunehmenden Defekte als pathologisch bewertet. Persistierende Defekte und Inhomogenitäten galten hingegen als nicht pathologisch. Die perfusionsszintigraphische Untersuchung errreichte mit 92% Sensitivität den höchsten Wert, jedoch mit einer relativ geringen Spezifität von 60% und einer diagnostischen Genauigkeit von 69%. Die Myokardszintigraphie zeigte sich bezüglich der Sensitivität der Stressechokardiographie überlegen, was zu einem Vorteil bei der Erkennung einer koronaren Herzerkrankung führt. Nachteilig ist die große Rate an falsch positiven Befunden. Die Perfusionsszintigraphie zeigte somit im Vergleich zur Stressechokardiographie an diesem Kollektiv eine deutlich niedrigere diagnostische Genauigkeit (69% vs. 78%). Die vorliegende Studie zeigt, dass die Kontraststressechokardiographie als nichtinvasive Untersuchungsmethode bei der Diagnose der hämodynamischen Relevanz mittelgradiger Stenosen eine bedeutende Rolle spielt, da sie die nichtinvasive Beurteilung der funktionellen Auswirkung einer Koronarstenose gegenüber der nativen Untersuchung verbessert. Der limitierende Faktor dieser Arbeit ist die nur begrenzte Anzahl der Studienteilnehmer. Es bedarf weiterer Untersuchungsreihen an größeren Studienpopulationen, um die verschiedenen Beurteilungsmodelle für die Kontrastmitteluntersuchung zu bestätigen und im klinischen Alltag zu etablieren. N2 - In patients with intermediate coronary stenoses the present study was designed to evaluate the diagnostic accuracy of two non-invasive methods. Dobutamine stress echocardiography (DSE) with and without using an ultrasound contrast agent (UCA) and single photon emission computer tomography (SPECT) were compared in 48 patients with angiographically determined intermediate coronary stenoses (50-75%). All measurements were performed simultaneous using pharmacologically induced exercise. As reference standard for the verification of the hemodynamic relevance of the intermediate coronary stenoses the intracoronary pressure wire measurement of fractional flow reserve (FFR) were chosen. Secondary, the present study also investigated the additional diagnostic benefit of ultrasound contrast agents of the second generation (Optison®, Sonovue®) for the detection of abnormalities of wall motion. The interpretation and segment analyses of all echocardiographic measurements at rest and during exercise were done according to the recommendations of the American Society of Echocardiography (ASE) and interpreted by two independent and blinded observers. A significant improvement of the assesment of wall motion abnormalities was observed at rest and also at maximal exercise after application of UCA. This effect was more obvious in the apical, anterior and lateral wall segments suggesting an improvement for the assessment of the left anterior descendens artery and the circumflex artery. However only wall segments of the right coronary artery could be interpreted sufficiently under native conditions but no improvement after application of UCA was seen. An additional focus of the study was the validation of different models for the interpretation of wall abnormalities especially after application of UCA. Therefore the standard model for native measurements described by Hoffmann et al. and different approaches were compared. The highest diagnostic accuracy were observed when new induced, non changed or worsened wall abnormalities in at least two segments border on each other called as pathological. In comparison during SPECT every worsened segment, like validated before, was interpreted as pathological. With respect to this SPECT reached a sensitivity of 92%, but only a specifity of 60% and a diagnostic accuracy of 69% (DSE 78%). In conclusion DSE SPECT showed better results in the detection of coronary artery diseases but also produced an unfavourable high value of wrong positive results. The presented study showed the encouraging role of DSE using UCA for the non invasive assessment of patients with intermediate coronary stenoses. Although the study is limited by the relatively small number of patients, the results suggest an increasing clinical relevance of DSE using UCA in patients with coronary artery diseases. KW - Echokardiographie KW - Dobutamin- Stressechokardiographie KW - SPECT KW - Ultraschallkontrastmittel KW - mittelgradige Koronarstenosen KW - dobutamine- stressechocardiography KW - SPECT KW - ultrasound contrast agent KW - intermediate coronary stenoses KW - pressure wire measurement Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-18033 ER -