@article{PetritschKoestlerGassenmaieretal.2016, author = {Petritsch, Bernhard and K{\"o}stler, Herbert and Gassenmaier, Tobias and Kunz, Andreas S and Bley, Thorsten A and Horn, Michael}, title = {An investigation into potential gender-specific differences in myocardial triglyceride content assessed by \(^{1}\)H-Magnetic Resonance Spectroscopy at 3Tesla}, series = {Journal of International Medical Research}, volume = {44}, journal = {Journal of International Medical Research}, number = {3}, doi = {10.1177/0300060515603884}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168808}, pages = {585-591}, year = {2016}, abstract = {Objective: Over the past decade, myocardial triglyceride content has become an accepted biomarker for chronic metabolic and cardiac disease. The purpose of this study was to use proton (hydrogen 1)-magnetic resonance spectroscopy (\(^{1}\)H-MRS) at 3Tesla (3 T) field strength to assess potential gender-related differences in myocardial triglyceride content in healthy individuals. Methods: Cardiac MR imaging was performed to enable accurate voxel placement and obtain functional and morphological information. Double triggered (i.e., ECG and respiratory motion gating) \(^{1}\)H-MRS was used to quantify myocardial triglyceride levels for each gender. Two-sample t-test and Mann-Whitney U-test were used for statistical analyses. Results: In total, 40 healthy volunteers (22 male, 18 female; aged >18 years and age matched) were included in the study. Median myocardial triglyceride content was 0.28\% (interquartile range [IQR] 0.17-0.42\%) in male and 0.24\% (IQR 0.14-0.45\%) in female participants, and no statistically significant difference was observed between the genders. Furthermore, no gender-specific difference in ejection fraction was observed, although on average, male participants presented with a higher mean ± SD left ventricular mass (136.3 ± 25.2 g) than female participants (103.9 ± 16.1 g). Conclusions: The study showed that \(^{1}\)H-MRS is a capable, noninvasive tool for acquisition of myocardial triglyceride metabolites. Myocardial triglyceride concentration was shown to be unrelated to gender in this group of healthy volunteers.}, language = {en} } @article{MihatschBeissertPomperetal.2022, author = {Mihatsch, Patrick W. and Beissert, Matthias and Pomper, Martin G. and Bley, Thorsten A. and Seitz, Anna K. and K{\"u}bler, Hubert and Buck, Andreas K. and Rowe, Steven P. and Serfling, Sebastian E. and Hartrampf, Philipp E. and Werner, Rudolf A.}, title = {Changing threshold-based segmentation has no relevant impact on semi-quantification in the context of structured reporting for PSMA-PET/CT}, series = {Cancers}, volume = {14}, journal = {Cancers}, number = {2}, issn = {2072-6694}, doi = {10.3390/cancers14020270}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254782}, year = {2022}, abstract = {Prostate-specific membrane antigen (PSMA)-directed positron emission tomography/computed tomography (PET/CT) is increasingly utilized for staging of men with prostate cancer (PC). To increase interpretive certainty, the standardized PSMA reporting and data system (RADS) has been proposed. Using PSMA-RADS, we characterized lesions in 18 patients imaged with \(^{18}\)F-PSMA-1007 PET/CT for primary staging and determined the stability of semi-quantitative parameters. Six hundred twenty-three lesions were categorized according to PSMA-RADS and manually segmented. In this context, PSMA-RADS-3A (soft-tissue) or -3B (bone) lesions are defined as being indeterminate for the presence of PC. For PMSA-RADS-4 and -5 lesions; however, PC is highly likely or almost certainly present [with further distinction based on absence (PSMA-RADS-4) or presence (PSMA-RADS-5) of correlative findings on CT]. Standardized uptake values (SUV\(_{max}\), SUV\(_{peak}\), SUV\(_{mean}\)) were recorded, and volumetric parameters [PSMA-derived tumor volume (PSMA-TV); total lesion PSMA (TL-PSMA)] were determined using different maximum intensity thresholds (MIT) (40 vs. 45 vs. 50\%). SUV\(_{max}\) was significantly higher in PSMA-RADS-5 lesions compared to all other PSMA-RADS categories (p ≤ 0.0322). In particular, the clinically challenging PSMA-RADS-3A lesions showed significantly lower SUV\(_{max}\) and SUV\(_{peak}\) compared to the entire PSMA-RADS-4 or -5 cohort (p < 0.0001), while for PSMA-RADS-3B this only applies when compared to the entire PSMA-RADS-5 cohort (p < 0.0001), but not to the PSMA-RADS-4 cohort (SUV\(_{max}\), p = 0.07; SUV\(_{peak}\), p = 0.08). SUV\(_{mean}\) (p = 0.30) and TL-PSMA (p = 0.16) in PSMA-RADS-5 lesions were not influenced by changing the MIT, while PSMA-TV showed significant differences when comparing 40 vs. 50\% MIT (p = 0.0066), which was driven by lymph nodes (p = 0.0239), but not bone lesions (p = 0.15). SUV\(_{max}\) was significantly higher in PSMA-RADS-5 lesions compared to all other PSMA-RADS categories in \(^{18}\)F-PSMA-1007 PET/CT. As such, the latter parameter may assist the interpreting molecular imaging specialist in assigning the correct PSMA-RADS score to sites of disease, thereby increasing diagnostic certainty. In addition, changes of the MIT in PSMA-RADS-5 lesions had no significant impact on SUV\(_{mean}\) and TL-PSMA in contrast to PSMA-TV.}, language = {en} } @article{WengHeidenreichMetzetal.2021, author = {Weng, Andreas M. and Heidenreich, Julius F. and Metz, Corona and Veldhoen, Simon and Bley, Thorsten A. and Wech, Tobias}, title = {Deep learning-based segmentation of the lung in MR-images acquired by a stack-of-spirals trajectory at ultra-short echo-times}, series = {BMC Medical Imaging}, volume = {21}, journal = {BMC Medical Imaging}, doi = {10.1186/s12880-021-00608-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260520}, year = {2021}, abstract = {Background Functional lung MRI techniques are usually associated with time-consuming post-processing, where manual lung segmentation represents the most cumbersome part. The aim of this study was to investigate whether deep learning-based segmentation of lung images which were scanned by a fast UTE sequence exploiting the stack-of-spirals trajectory can provide sufficiently good accuracy for the calculation of functional parameters. Methods In this study, lung images were acquired in 20 patients suffering from cystic fibrosis (CF) and 33 healthy volunteers, by a fast UTE sequence with a stack-of-spirals trajectory and a minimum echo-time of 0.05 ms. A convolutional neural network was then trained for semantic lung segmentation using 17,713 2D coronal slices, each paired with a label obtained from manual segmentation. Subsequently, the network was applied to 4920 independent 2D test images and results were compared to a manual segmentation using the S{\o}rensen-Dice similarity coefficient (DSC) and the Hausdorff distance (HD). Obtained lung volumes and fractional ventilation values calculated from both segmentations were compared using Pearson's correlation coefficient and Bland Altman analysis. To investigate generalizability to patients outside the CF collective, in particular to those exhibiting larger consolidations inside the lung, the network was additionally applied to UTE images from four patients with pneumonia and one with lung cancer. Results The overall DSC for lung tissue was 0.967 ± 0.076 (mean ± standard deviation) and HD was 4.1 ± 4.4 mm. Lung volumes derived from manual and deep learning based segmentations as well as values for fractional ventilation exhibited a high overall correlation (Pearson's correlation coefficent = 0.99 and 1.00). For the additional cohort with unseen pathologies / consolidations, mean DSC was 0.930 ± 0.083, HD = 12.9 ± 16.2 mm and the mean difference in lung volume was 0.032 ± 0.048 L. Conclusions Deep learning-based image segmentation in stack-of-spirals based lung MRI allows for accurate estimation of lung volumes and fractional ventilation values and promises to replace the time-consuming step of manual image segmentation in the future.}, language = {en} } @article{WengKoestlerBleyetal.2021, author = {Weng, Andreas M. and K{\"o}stler, Herbert and Bley, Thorsten A. and Ritter, Christian O.}, title = {Effect of short-term smoking \& L-arginine on coronary endothelial function assessed by cardiac magnetic resonance cold pressor testing: a pilot study}, series = {BMC Cardiovascular Disorders}, volume = {21}, journal = {BMC Cardiovascular Disorders}, doi = {10.1186/s12872-021-02050-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260559}, year = {2021}, abstract = {Background The effect of smoking on coronary vasomotion has been investigated in the past with various imaging techniques in both short- and long-term smokers. Additionally, coronary vasomotion has been shown to be normalized in long-term smokers by L-Arginine acting as a substrate for NO synthase, revealing the coronary endothelium as the major site of abnormal vasomotor response. Aim of the prospective cohort study was to investigate coronary vasomotion of young healthy short-term smokers via magnetic resonance cold pressor test with and without the administration of L-Arginine and compare obtained results with the ones from nonsmokers. Methods Myocardial blood flow (MBF) was quantified with first-pass perfusion MRI on a 1.5 T scanner in healthy short-term smokers (N = 10, age: 25.0 ± 2.8 years, 5.0 ± 2.9 pack years) and nonsmokers (N = 10, age: 34.3 ± 13.6) both at rest and during cold pressor test (CPT). Smokers underwent an additional examination after administration of L-Arginine within a median of 7 days of the na{\"i}ve examination. Results MBF at rest turned out to be 0.77 ± 0.30 (smokers with no L-Arginine; mean ± standard deviation), 0.66 ± 0.21 (smokers L-Arginine) and 0.84 ± 0.08 (nonsmokers). Values under CPT were 1.21 ± 0.42 (smokers no L-Arginine), 1.09 ± 0.35 (smokers L-Arginine) and 1.63 ± 0.33 (nonsmokers). In all groups, MBF was significantly increased under CPT compared to the corresponding rest examination (p < 0.05 in all cases). Additionally, MBF under CPT was significantly different between the smokers and the nonsmokers (p = 0.002). MBF at rest was significantly different between the smokers when L-Arginine was given and the nonsmokers (p = 0.035). Conclusion Short-term smokers showed a reduced response to cold both with and without the administration of L-Arginine. However, absolute MBF values under CPT were lower compared to nonsmokers independently of L-Arginine administration.}, language = {en} } @article{HerzStefanescuLohretal.2022, author = {Herz, Stefan and Stefanescu, Maria R. and Lohr, David and Vogel, Patrick and Kosmala, Aleksander and Terekhov, Maxim and Weng, Andreas M. and Grunz, Jan-Peter and Bley, Thorsten A. and Schreiber, Laura M.}, title = {Effects of image homogeneity on stenosis visualization at 7 T in a coronary artery phantom study: With and without B1-shimming and parallel transmission}, series = {PloS One}, volume = {17}, journal = {PloS One}, number = {6}, doi = {10.1371/journal.pone.0270689}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300129}, year = {2022}, abstract = {Background To investigate the effects of B\(_1\)-shimming and radiofrequency (RF) parallel transmission (pTX) on the visualization and quantification of the degree of stenosis in a coronary artery phantom using 7 Tesla (7 T) magnetic resonance imaging (MRI). Methods Stenosis phantoms with different grades of stenosis (0\%, 20\%, 40\%, 60\%, 80\%, and 100\%; 5 mm inner vessel diameter) were produced using 3D printing (clear resin). Phantoms were imaged with four different concentrations of diluted Gd-DOTA representing established arterial concentrations after intravenous injection in humans. Samples were centrally positioned in a thorax phantom of 30 cm diameter filled with a custom-made liquid featuring dielectric properties of muscle tissue. MRI was performed on a 7 T whole-body system. 2D-gradient-echo sequences were acquired with an 8-channel transmit 16-channel receive (8 Tx / 16 Rx) cardiac array prototype coil with and without pTX mode. Measurements were compared to those obtained with identical scan parameters using a commercially available 1 Tx / 16 Rx single transmit coil (sTX). To assess reproducibility, measurements (n = 15) were repeated at different horizontal angles with respect to the B0-field. Results B\(_1\)-shimming and pTX markedly improved flip angle homogeneity across the thorax phantom yielding a distinctly increased signal-to-noise ratio (SNR) averaged over a whole slice relative to non-manipulated RF fields. Images without B\(_1\)-shimming showed shading artifacts due to local B\(_1\)\(^+\)-field inhomogeneities, which hampered stenosis quantification in severe cases. In contrast, B\(_1\)-shimming and pTX provided superior image homogeneity. Compared with a conventional sTX coil higher grade stenoses (60\% and 80\%) were graded significantly (p<0.01) more precise. Mild to moderate grade stenoses did not show significant differences. Overall, SNR was distinctly higher with B\(_1\)-shimming and pTX than with the conventional sTX coil (inside the stenosis phantoms 14\%, outside the phantoms 32\%). Both full and half concentration (10.2 mM and 5.1 mM) of a conventional Gd-DOTA dose for humans were equally suitable for stenosis evaluation in this phantom study. Conclusions B\(_1\)-shimming and pTX at 7 T can distinctly improve image homogeneity and therefore provide considerably more accurate MR image analysis, which is beneficial for imaging of small vessel structures.}, language = {en} } @article{RichterWechWengetal.2020, author = {Richter, Julian A. J. and Wech, Tobias and Weng, Andreas M. and Stich, Manuel and Weick, Stefan and Breuer, Kathrin and Bley, Thorsten A. and K{\"o}stler, Herbert}, title = {Free-breathing self-gated 4D lung MRI using wave-CAIPI}, series = {Magnetic Resonance in Medicine}, volume = {84}, journal = {Magnetic Resonance in Medicine}, number = {6}, doi = {10.1002/mrm.28383}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218075}, pages = {3223 -- 3233}, year = {2020}, abstract = {Purpose The aim of this study was to compare the wave-CAIPI (controlled aliasing in parallel imaging) trajectory to the Cartesian sampling for accelerated free-breathing 4D lung MRI. Methods The wave-CAIPI k-space trajectory was implemented in a respiratory self-gated 3D spoiled gradient echo pulse sequence. Trajectory correction applying the gradient system transfer function was used, and images were reconstructed using an iterative conjugate gradient SENSE (CG SENSE) algorithm. Five healthy volunteers and one patient with squamous cell carcinoma in the lung were examined on a clinical 3T scanner, using both sampling schemes. For quantitative comparison of wave-CAIPI and standard Cartesian imaging, the normalized mutual information and the RMS error between retrospectively accelerated acquisitions and their respective references were calculated. The SNR ratios were investigated in a phantom study. Results The obtained normalized mutual information values indicate a lower information loss due to acceleration for the wave-CAIPI approach. Average normalized mutual information values of the wave-CAIPI acquisitions were 10\% higher, compared with Cartesian sampling. Furthermore, the RMS error of the wave-CAIPI technique was lower by 19\% and the SNR was higher by 14\%. Especially for short acquisition times (down to 1 minute), the undersampled Cartesian images showed an increased artifact level, compared with wave-CAIPI. Conclusion The application of the wave-CAIPI technique to 4D lung MRI reduces undersampling artifacts, in comparison to a Cartesian acquisition of the same scan time. The benefit of wave-CAIPI sampling can therefore be traded for shorter examinations, or enhancing image quality of undersampled 4D lung acquisitions, keeping the scan time constant.}, language = {en} } @article{GuggenbergerBleyVogtetal.2022, author = {Guggenberger, Konstanze V. and Bley, Thorsten A. and Vogt, Marius L. and Urbach, Horst and Meckel, Stephan}, title = {High-Resolution Black Blood Vessel Wall Imaging in COVID-19 Encephalopathy-Is it Really Endotheliitis?}, series = {Clinical Neuroradiology}, volume = {32}, journal = {Clinical Neuroradiology}, number = {1}, doi = {10.1007/s00062-021-01109-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-264794}, pages = {295-296}, year = {2022}, abstract = {No abstract available.}, language = {en} } @article{BluemelLinkeHerrmannetal.2016, author = {Bluemel, Christina and Linke, Fraenze and Herrmann, Ken and Simunovic, Iva and Eiber, Matthias and Kestler, Christian and Buck, Andreas K. and Schirbel, Andreas and Bley, Thorsten A. and Wester, Hans-Juergen and Vergho, Daniel and Becker, Axel}, title = {Impact of \(^{68}\)Ga-PSMA PET/CT on salvage radiotherapy planning in patients with prostate cancer and persisting PSA values or biochemical relapse after prostatectomy}, series = {EJNMMI Research}, volume = {6}, journal = {EJNMMI Research}, number = {78}, doi = {10.1186/s13550-016-0233-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147798}, year = {2016}, abstract = {Background Salvage radiotherapy (SRT) is clinically established in prostate cancer (PC) patients with PSA persistence or biochemical relapse (BCR) after prior radical surgery. PET/CT imaging prior to SRT may be performed to localize disease recurrence. The recently introduced \(^{68}\)Ga-PSMA outperforms other PET tracers for detection of recurrence and is therefore expected also to impact radiation planning. Forty-five patients with PSA persistence (16 pts) or BCR (29 pts) after prior prostatectomy, scheduled to undergo SRT of the prostate bed, underwent \(^{68}\)Ga-PSMA PET/CT. The median PSA level was 0.67 ng/ml. The impact of \(^{68}\)Ga-PSMA PET/CT on the treatment decision was assessed. Patients with oligometastatic (≤5 lesions) PC underwent radiotherapy (RT), with the extent of the RT area and dose escalation being based on PET positivity. Results Suspicious lesions were detected in 24/45 (53.3 \%) patients. In 62.5 \% of patients, lesions were only detected by 68Ga-PSMA PET. Treatment was changed in 19/45 (42.2 \%) patients, e.g., extending SRT to metastases (9/19), administering dose escalation in patients with morphological local recurrence (6/19), or replacing SRT by systemic therapy (2/19). 38/45 (84.4 \%) followed the treatment recommendation, with data on clinical follow-up being available in 21 patients treated with SRT. All but one showed biochemical response (mean PSA decline 78 ± 19 \%) within a mean follow-up of 8.12 ± 5.23 months. Conclusions \(^{68}\)Ga-PSMA PET/CT impacts treatment planning in more than 40 \% of patients scheduled to undergo SRT. Future prospective studies are needed to confirm this significant therapeutic impact on patients prior to SRT.}, language = {en} } @article{GuggenbergerVogtSongetal.2023, author = {Guggenberger, Konstanze V. and Vogt, Marius L. and Song, Jae W. and Weng, Andreas M. and Fr{\"o}hlich, Matthias and Schmalzing, Marc and Venhoff, Nils and Hillenkamp, Jost and Pham, Mirko and Meckel, Stephan and Bley, Thorsten A.}, title = {Intraorbital findings in giant cell arteritis on black blood MRI}, series = {European Radiology}, volume = {33}, journal = {European Radiology}, number = {4}, doi = {10.1007/s00330-022-09256-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324978}, pages = {2529-2535}, year = {2023}, abstract = {Objective Blindness is a feared complication of giant cell arteritis (GCA). However, the spectrum of pathologic orbital imaging findings on magnetic resonance imaging (MRI) in GCA is not well understood. In this study, we assess inflammatory changes of intraorbital structures on black blood MRI (BB-MRI) in patients with GCA compared to age-matched controls. Methods In this multicenter case-control study, 106 subjects underwent BB-MRI. Fifty-six patients with clinically or histologically diagnosed GCA and 50 age-matched controls without clinical or laboratory evidence of vasculitis were included. All individuals were imaged on a 3-T MR scanner with a post-contrast compressed-sensing (CS) T1-weighted sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) BB-MRI sequence. Imaging results were correlated with available clinical symptoms. Results Eighteen of 56 GCA patients (32\%) showed inflammatory changes of at least one of the intraorbital structures. The most common finding was enhancement of at least one of the optic nerve sheaths (N = 13, 72\%). Vessel wall enhancement of the ophthalmic artery was unilateral in 8 and bilateral in 3 patients. Enhancement of the optic nerve was observed in one patient. There was no significant correlation between imaging features of inflammation and clinically reported orbital symptoms (p = 0.10). None of the age-matched control patients showed any inflammatory changes of intraorbital structures. Conclusions BB-MRI revealed inflammatory findings in the orbits in up to 32\% of patients with GCA. Optic nerve sheath enhancement was the most common intraorbital inflammatory change on BB-MRI. MRI findings were independent of clinically reported orbital symptoms. Key Points • Up to 32\% of GCA patients shows signs of inflammation of intraorbital structures on BB-MRI. • Enhancement of the optic nerve sheath is the most common intraorbital finding in GCA patients on BB-MRI. • Features of inflammation of intraorbital structures are independent of clinically reported symptoms.}, language = {en} } @article{VogelMarkertRueckertetal.2019, author = {Vogel, Patrick and Markert, Jonathan and R{\"u}ckert, Martin A. and Herz, Stefan and Keßler, Benedikt and Dremel, Kilian and Althoff, Daniel and Weber, Matthias and Buzug, Thorsten M. and Bley, Thorsten A. and Kullmann, Walter H. and Hanke, Randolf and Zabler, Simon and Behr, Volker C.}, title = {Magnetic Particle Imaging meets computed tomography: first simultaneous imaging}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-48960-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202501}, pages = {12627}, year = {2019}, abstract = {Magnetic Particle Imaging (MPI) is a promising new tomographic modality for fast as well as three-dimensional visualization of magnetic material. For anatomical or structural information an additional imaging modality such as computed tomography (CT) is required. In this paper, the first hybrid MPI-CT scanner for multimodal imaging providing simultaneous data acquisition is presented.}, language = {en} }