@article{WernerMarcusSheikhbahaeietal.2018, author = {Werner, Rudolf A. and Marcus, Charles and Sheikhbahaei, Sara and Solnes, Lilja B. and Leal, Jeffrey P. and Du, Yong and Rowe, Steven P. and Higuchi, Takahiro and Buck, Andreas K. and Lapa, Constantin and Javadi, Mehrbod S.}, title = {Visual and Semiquantitative Accuracy in Clinical Baseline 123I-Ioflupane SPECT/CT Imaging}, series = {Clinical Nuclear Medicine}, volume = {44}, journal = {Clinical Nuclear Medicine}, number = {1}, issn = {1536-0229}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168181}, year = {2018}, abstract = {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.}, subject = {SPECT}, language = {en} } @phdthesis{Nowotny2006, author = {Nowotny, Anja}, title = {Vergleich der diagnostischen Wertigkeit der Dobutamin-Kontraststressechokardiographie und der Myokardszintigraphie mit der Referenzmethode Druckdrahtmessung zur Beurteilung mittelgradiger Koronarstenosen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-18033}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2006}, abstract = {In der vorliegenden klinischen Studie untersuchten wir die diagnostische Genauigkeit zweier nicht invasiver Verfahren, n{\"a}mlich des Nachweises der nativen und kontrastmittelverst{\"a}rkten Stressechokardiographie sowie der Myokardszintigraphie bei visuell als mittelgradig eingesch{\"a}tzten Koronarstenosen. Eingeschlossen wurden 48 Patienten mit einer angiographisch nachgewiesenen 50- 75\% Lumenreduktion eines Herzkranzgef{\"a}ßes. Die Untersuchungen wurden simultan mittels pharmakologischer Belastung (Dobutamin) durchgef{\"u}hrt und die Ergebnisse miteinander verglichen. Als Referenzmethode diente die Druckdrahtmessung, welche eine Objektivierung der h{\"a}modynamischen Relevanz besonders mittelgradiger Koronarstenosen durch die Ermittlung der fraktionellen Flussreserve als Quotienten aus post- und pr{\"a}stenotischem Druck direkt im betroffenen Koronargef{\"a}ß erm{\"o}glicht. 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 gem{\"a}ß 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 f{\"u}r die klinische Praxis vor allem eine Verbesserung der Beurteilung der h{\"a}modynamischen 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 bez{\"u}glich der Wandbewegungsst{\"o}rungen von zwei unabh{\"a}ngigen und erfahrenen Untersuchern ohne Kenntnis der Ergebnisse der anderen Isch{\"a}mietests bzw. des Ergebnisses der Koronarangiographie und der Bestimmung der fraktionellen Flussreserve beurteilt. Die Nativuntersuchungen wurden gem{\"a}ß den standardisierten Richtlinien von Hoffmann et al. interpretiert. F{\"u}r die Bewertung der kontrastverst{\"a}rkten Stressechokardiogramme wurde, sich an den Ergebnissen der Druckdrahtmessung orientierend, ein optimales Bewertungsmodell gesucht. Die gr{\"o}ßte diagnostische Genauigkeit ergab sich, wenn neu induzierte, gleich bleibende oder zunehmende Wandbewegungsst{\"o}rungen 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 Inhomogenit{\"a}ten galten hingegen als nicht pathologisch. Die perfusionsszintigraphische Untersuchung errreichte mit 92\% Sensitivit{\"a}t den h{\"o}chsten Wert, jedoch mit einer relativ geringen Spezifit{\"a}t von 60\% und einer diagnostischen Genauigkeit von 69\%. Die Myokardszintigraphie zeigte sich bez{\"u}glich der Sensitivit{\"a}t der Stressechokardiographie {\"u}berlegen, was zu einem Vorteil bei der Erkennung einer koronaren Herzerkrankung f{\"u}hrt. 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 h{\"a}modynamischen Relevanz mittelgradiger Stenosen eine bedeutende Rolle spielt, da sie die nichtinvasive Beurteilung der funktionellen Auswirkung einer Koronarstenose gegen{\"u}ber der nativen Untersuchung verbessert. Der limitierende Faktor dieser Arbeit ist die nur begrenzte Anzahl der Studienteilnehmer. Es bedarf weiterer Untersuchungsreihen an gr{\"o}ßeren Studienpopulationen, um die verschiedenen Beurteilungsmodelle f{\"u}r die Kontrastmitteluntersuchung zu best{\"a}tigen und im klinischen Alltag zu etablieren.}, language = {de} } @inproceedings{WernerMarcusSheikhbahaeietal.2018, author = {Werner, Rudolf A. and Marcus, Charles and Sheikhbahaei, Sara and Higuchi, Takahiro and Solnes, Lilja B. and Rowe, Steven P. and Buck, Andreas K. and Lapa, Constantin and Javadi, Mehrbod S.}, title = {The Impact of Ageing on Dopamine Transporter Imaging}, series = {Journal of Nuclear Medicine}, volume = {59}, booktitle = {Journal of Nuclear Medicine}, number = {Supplement No 1}, issn = {0161-5505}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162213}, pages = {1646}, year = {2018}, abstract = {No abstract available.}, subject = {Parkinson-Krankheit}, language = {en} } @phdthesis{Hoffmann2023, author = {Hoffmann, Jan Vincent}, title = {Small-animal SPECT with Two Stationary Detectors: Performance Evaluation and Image Quality Assessment of Multi-pinhole Collimators}, doi = {10.25972/OPUS-32819}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-328195}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {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.}, subject = {SPECT}, language = {en} } @article{ChenWernerJavadietal.2015, author = {Chen, Xinyu and Werner, Rudolf A. and Javadi, Mehrbod S. and Maya, Yoshifumi and Decker, Michael and Lapa, Constantin and Herrmann, Ken and Higuchi, Takahiro}, title = {Radionuclide imaging of neurohormonal system of the heart}, series = {Theranostics}, volume = {5}, journal = {Theranostics}, number = {6}, doi = {10.7150/thno.10900}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149205}, pages = {545-558}, year = {2015}, abstract = {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.}, language = {en} } @article{HoffmannJanssenKannoetal.2020, author = {Hoffmann, Jan V. and Janssen, Jan P. and Kanno, Takayuki and Shibutani, Takayuki and Onoguchi, Masahisa and Lapa, Constantin and Grunz, Jan-Peter and Buck, Andreas K. and Higuchi, Takahiro}, title = {Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging}, series = {EJNMMI Physics}, volume = {7}, journal = {EJNMMI Physics}, doi = {10.1186/s40658-020-00335-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230361}, year = {2020}, abstract = {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.}, language = {en} } @article{WernerChenRoweetal.2018, author = {Werner, Rudolf A. and Chen, Xinyu and Rowe, Steven P. and Lapa, Constantin and Javadi, Mehrbod S. and Higuchi, Takahiro}, title = {Moving into the Next Era of PET Myocardial Perfusion Imaging - Introduction of Novel \(^{18}\)F-labeled Tracers}, series = {The International Journal of Cardiovascular Imaging}, journal = {The International Journal of Cardiovascular Imaging}, issn = {1569-5794}, doi = {10.1007/s10554-018-1469-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169134}, year = {2018}, abstract = {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.}, subject = {Positronenemissionstomografie}, language = {en} } @article{BuckDecristoforo2016, author = {Buck, Andreas and Decristoforo, Clemens}, title = {Highlights lecture EANM 2015: the search for nuclear medicine's superheroes}, series = {European Journal of Nuclear Medicine and Molecular Imaging}, volume = {43}, journal = {European Journal of Nuclear Medicine and Molecular Imaging}, number = {10}, doi = {10.1007/s00259-016-3423-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187613}, pages = {1910-1927}, year = {2016}, abstract = {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).}, language = {en} } @article{Werner2018, author = {Werner, Rudolf A.}, title = {Editorial: Cardiac Innervation Imaging as a Risk Stratification Tool for Potential Device Therapy Candidates}, series = {Journal of Nuclear Cardiology}, journal = {Journal of Nuclear Cardiology}, issn = {1071-3581}, doi = {10.1007/s12350-018-01475-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168465}, year = {2018}, abstract = {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.}, subject = {SPECT}, language = {en} } @inproceedings{WernerMarcusSheikhbahaeietal.2018, author = {Werner, Rudolf A. and Marcus, Charles and Sheikhbahaei, Sara and Higuchi, Takahiro and Solnes, Lilja B. and Rowe, Steven P. and Buck, Andreas K. and Lapa, Constantin and Javadi, Mehrbod S.}, title = {Diagnostic Accuracy of Visual Assessment of an Initial DaT-Scan in Comparison to a Fully Automatic Semiquantitative Method}, series = {Journal of Nuclear Medicine}, volume = {59}, booktitle = {Journal of Nuclear Medicine}, number = {Supplement No. 1}, issn = {0161-5505}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162208}, pages = {626}, year = {2018}, abstract = {No abstract available.}, subject = {Parkinson-Krankheit}, language = {en} } @phdthesis{Girardet2006, author = {Girardet, Fabian}, title = {Der kardiale BOLD-Effekt und die Narbendarstellung per delayed enhancement in der Magnetresonanztomographie im Vergleich zu Myokardszintigraphie und Koronarangiographie}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23266}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2006}, abstract = {Eine Koronare Herzkrankheit wird derzeit prim{\"a}r im Herzkatheterlabor diagnostiziert oder aus-geschlossen. Werden bei der Untersuchung Stenosen festgestellt, muß von der Morphologie auf die Bedeutung f{\"u}r das versorgte Myokard geschlossen werden. Der Untersucher kann dabei im Herzkatheterlabor nur bedingt beurteilen, inwiefern die Durchblutung des Herzens auch tats{\"a}ch-lich eingeschr{\"a}nkt ist. F{\"u}r den in diesem Fall notwendigen Isch{\"a}mienachweis steht neben der Myokardszintigraphie mittlerweile auch die kardiale Magnetresonanztomographie zur Verf{\"u}-gung. In Vorarbeiten dieser Arbeitsgruppe war es gelungen, das k{\"o}rpereigene Kontrastmittel H{\"a}mog-lobin zur Abbildung von Anpassungsvorg{\"a}ngen in poststenotischen Myokardarealen zu nutzen. Bei h{\"a}modynamisch relevanter Stenosierung war eine Verk{\"u}rzung der T2*-Zeit beobachtet worden, die auf eine erh{\"o}hte Konzentration des paramagnetischen Desoxyh{\"a}moglobin zur{\"u}ck-gef{\"u}hrt wurde. Dieser Zusammenhang wird als blood oxygenation level dependent(BOLD)-Effekt bezeichnet. In vorliegender Arbeit wurde die Technik der kardialen T2*-Messung an einem gr{\"o}ßeren 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 durchgef{\"u}hrt. Als konkurrierendes Verfahren wurde bei allen Patienten die Myo-kardszintigraphie mit Tc99m-Sestamibi durchgef{\"u}hrt. Bei der Auswertung der MRT-Daten zeigte sich, dass 30\% der gemessenen T2*-Zeiten zuvor festgelegten statistischen Kriterien nicht gen{\"u}gte und verworfen werden mußte. F{\"u}r den Ver-gleich der MRT mit der Koronarangiographie als Referenzmethode wurde der kardiale Kurz-achsenschnitt auf midventrikul{\"a}rer Ebene zu Segmenten von VW/HW und RIVA, RCX, RCA zusammengefasst. Von Segmenten, die deutlich k{\"u}rzere T2*-Zeiten aufwiesen, als die {\"u}brigen Segmente, wurde angenommen, sie l{\"a}gen im Stromgebiet stenosierter Koronargef{\"a}ße. Der computergest{\"u}tzte 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 ({\"U}bereinstimmung 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 {\"U}bereinstimmung mit der Koronarangi-ographie beurteilt wurden (RIVA 57,9\%, RCX 64,9\%, RCA 65,8\%). Insbesondere Patienten ohne h{\"a}modynamische Stenosierung waren gut an homogeneren Relaxationszeiten zu erkennen. Wie in Vorarbeiten gezeigt werden konnte, l{\"a}sst sich die diagnostische Leistungsf{\"a}higkeit durch ein Stressprotokoll weiter verbessern, so dass die BOLD-Bildgebung ein viel versprechendes Verfahren der kardialen Isch{\"a}miediagnostik darstellt. Parallel wurde in vorliegender Arbeit der Narbennachweis per delayed enhancement (LE) mit der Myokardszintigraphie verglichen. Abgestorbenes Myokard wird kollagen umgebaut und verf{\"u}gt danach {\"u}ber gr{\"o}ßere Zellzwischenr{\"a}ume als normaler Herzmuskel. Das vergr{\"o}ßerte Ver-teilungsvolumen und eine reduzierte Kapillardichte f{\"u}hren dazu, dass das applizierte Kontrast-mittel (Gadodiamide) von dort langsamer entfernt wird als in normalem Myokard. Werden die MRT-Bilder zeitlich verz{\"o}gert (10-30min) aufgenommen, l{\"a}sst sich auf diese Weise vernarbtes Herzgewebe an einem k{\"u}rzeren T1 erkennen. Der Vergleich des Narbennachweises der Myokardszintigraphie mit dem LE zeigte eine hohe {\"U}bereinstimmung. 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 Ver{\"a}nderungen abzubilden. In weiteren Studien sollte an selektierten Patientenkollektiven ermittelt werden, welchen Einfluss Begleiterkrankungen auf die Auspr{\"a}gung des BOLD-Effektes haben. Neben Fortschritten in der diagnostischen Zuverl{\"a}ssigkeit k{\"o}nnte dies zu einem besseren Verst{\"a}ndnis der Pathophysiologie kardialer Erkrankungen beitragen. Das delayed enhancement weist zuverl{\"a}ssig kardiales Narbengewebe nach und hat aufgrund h{\"o}herer Aufl{\"o}sung und fehlender Strahlenbelastung deutliche Vorteile gegen{\"u}ber der Myokard-szintigraphie.}, language = {de} } @phdthesis{Kuesters2019, author = {K{\"u}sters, Sebastian}, title = {Darstellung des nikotinergen Acetylcholinrezeptors bei Patienten mit idiopathischem Parkinson-Syndrom und Levodopa-induzierter Dyskinesie}, doi = {10.25972/OPUS-17874}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-178740}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2019}, abstract = {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) durchgef{\"u}hrt 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 h{\"o}here Dichte an nikotinergen Acetylcholinrezeptoren im Nucleus caudatus, haupts{\"a}chlich der Halbseite mit st{\"a}rkerer dopaminerger Degeneration. Dies st{\"u}tzt die Hypothese, dass sich die Dyskinesie nach Levodopa-Therapie aufgrund einer verst{\"a}rkten cholinergen Modulation im st{\"a}rker degenerierten Striatum entwickelt.}, subject = {Parkinson-Krankheit}, language = {de} } @phdthesis{Janssen2023, author = {Janßen, Jan Paul}, title = {Capabilities of a multi-pinhole SPECT system with two stationary detectors for in vivo imaging in rodents}, doi = {10.25972/OPUS-32860}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-328608}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {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.}, subject = {SPECT}, language = {en} } @article{LeubeGustafssonLassmannetal.2022, author = {Leube, Julian and Gustafsson, Johan and Lassmann, Michael and Salas-Ramirez, Maikol and Tran-Gia, Johannes}, title = {Analysis of a deep learning-based method for generation of SPECT projections based on a large Monte Carlo simulated dataset}, series = {EJNMMI Physics}, volume = {9}, journal = {EJNMMI Physics}, issn = {2197-7364}, doi = {10.1186/s40658-022-00476-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300697}, year = {2022}, abstract = {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.}, language = {en} }