@article{ThurnerAugustinBleyetal.2022,
  author    = {Thurner, Annette and Augustin, Anne Marie and Bley, Thorsten Alexander and Kickuth, Ralph},
  title     = {2D-perfusion angiography for intra-procedural endovascular treatment response assessment in chronic mesenteric ischemia: a feasibility study},
  series = {BMC Medical Imaging},
  volume    = {22},
  journal   = {BMC Medical Imaging},
  doi       = {10.1186/s12880-022-00820-7},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301131},
  year      = {2022},
  abstract  = {Background Endovascular revascularization has become the first-line treatment of chronic mesenteric ischemia (CMI). The qualitative visual analysis of digital subtraction angiography (DSA) is dependent on observer experience and prone to interpretation errors. We evaluate the feasibility of 2D-Perfusion Angiography (2D-PA) for objective, quantitative treatment response assessment in CMI. Methods 49 revascularizations in 39 patients with imaging based evidence of mesenteric vascular occlusive disease and clinical signs of CMI were included in this retrospective study. To assess perfusion changes by 2D-PA, DSA-series were post-processed using a dedicated, commercially available software. Regions of interest (ROI) were placed in the pre- and post-stenotic artery segment. In aorto-ostial disease, the inflow ROI was positioned at the mesenteric artery orifice. The ratios outflow to inflow ROI for peak density (PD), time to peak and area-under-the-curve (AUC) were computed and compared pre- and post-interventionally. We graded motion artifacts by means of a four-point scale. Feasibility of 2D-PA and changes of flow parameters were evaluated. Results Motion artifacts due to a mobile vessel location beneath the diaphragm or within the mesenteric root, branch vessel superimposition and inadequate contrast enhancement at the inflow ROI during manually conducted DSA-series via selective catheters owing to steep vessel angulation, necessitated exclusion of 26 measurements from quantitative flow evaluation. The feasibility rate was 47\%. In 23 technically feasible assessments, PD\(_{outflow}\)/PD\(_{inflow}\) increased by 65\% (p < 0.001) and AUC\(_{outflow}\)/AUC\(_{inflow}\) increased by 85\% (p < 0.001). The time to peak density values in the outflow ROI accelerated only minimally without reaching statistical significance. Age, BMI, target vessel (celiac trunk, SMA or IMA), stenosis location (ostial or truncal), calcification severity, plaque composition or the presence of a complex stenosis did not reach statistical significance in their distribution among the feasible and non-feasible group (p > 0.05). Conclusions Compared to other vascular territories and indications, the feasibility of 2D-PA in mesenteric revascularization for CMI was limited. Unfavorable anatomic conditions contributed to a high rate of inconclusive 2D-PA results.},
  language  = {en}
}
@article{GrunzWenigKunzetal.2020,
  author    = {Grunz, Jan-Peter and Wenig, Andreas Max and Kunz, Andreas Steven and Veyhl-Wichmann, Maike and Schmitt, Rainer and Gietzen, Carsten Herbert and Pennig, Lenhard and Herz, Stefan and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Gassenmaier, Tobias},
  title     = {3D cone-beam CT with a twin robotic x-ray system in elbow imaging: comparison of image quality to high-resolution multidetector CT},
  series = {European Radiology Experimental},
  volume    = {4},
  journal   = {European Radiology Experimental},
  doi       = {10.1186/s41747-020-00177-y},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229877},
  year      = {2020},
  abstract  = {Background Elbow imaging is challenging with conventional multidetector computed tomography (MDCT), while cone-beam CT (CBCT) provides superior options. We compared intra-individually CBCT versus MDCT image quality in cadaveric elbows. Methods A twin robotic x-ray system with new CBCT mode and a high-resolution clinical MDCT were compared in 16 cadaveric elbows. Both systems were operated with a dedicated low-dose (LD) protocol (equivalent volume CT dose index [CTDI\(_{vol(16 cm)}\)] = 3.3 mGy) and a regular clinical scan dose (RD) protocol (CTDI\(_{vol(16 cm)}\) = 13.8 mGy). Image quality was evaluated by two radiologists (R1 and R2) on a seven-point Likert scale, and estimation of signal intensity in cancellous bone was conducted. Wilcoxon signed-rank tests and intraclass correlation coefficient (ICC) statistics were used. Results The CBCT prototype provided superior subjective image quality compared to MDCT scans (for RD, p ≤ 0.004; for LD, p ≤ 0.001). Image quality was rated very good or excellent in 100\% of the cases by both readers for RD CBCT, 100\% (R1) and 93.8\% (R2) for LD CBCT, 62.6\% and 43.8\% for RD MDCT, and 0.0\% and 0.0\% for LD MDCT. Single-measure ICC was 0.95 (95\% confidence interval 0.91-0.97; p < 0.001). Software-based assessment supported subjective findings with less "undecided" pixels in CBCT than dose-equivalent MDCT (p < 0.001). No significant difference was found between LD CBCT and RD MDCT. Conclusions In cadaveric elbow studies, the tested cone-beam CT prototype delivered superior image quality compared to high-end multidetector CT and showed a potential for considerable dose reduction.},
  language  = {en}
}
@article{WechAnkenbrandBleyetal.2022,
  author    = {Wech, Tobias and Ankenbrand, Markus Johannes and Bley, Thorsten Alexander and Heidenreich, Julius Frederik},
  title     = {A data-driven semantic segmentation model for direct cardiac functional analysis based on undersampled radial MR cine series},
  series = {Magnetic Resonance in Medicine},
  volume    = {87},
  journal   = {Magnetic Resonance in Medicine},
  number    = {2},
  doi       = {10.1002/mrm.29017},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257616},
  pages     = {972-983},
  year      = {2022},
  abstract  = {Purpose Image acquisition and subsequent manual analysis of cardiac cine MRI is time-consuming. The purpose of this study was to train and evaluate a 3D artificial neural network for semantic segmentation of radially undersampled cardiac MRI to accelerate both scan time and postprocessing. Methods A database of Cartesian short-axis MR images of the heart (148,500 images, 484 examinations) was assembled from an openly accessible database and radial undersampling was simulated. A 3D U-Net architecture was pretrained for segmentation of undersampled spatiotemporal cine MRI. Transfer learning was then performed using samples from a second database, comprising 108 non-Cartesian radial cine series of the midventricular myocardium to optimize the performance for authentic data. The performance was evaluated for different levels of undersampling by the Dice similarity coefficient (DSC) with respect to reference labels, as well as by deriving ventricular volumes and myocardial masses. Results Without transfer learning, the pretrained model performed moderately on true radial data [maximum number of projections tested, P = 196; DSC = 0.87 (left ventricle), DSC = 0.76 (myocardium), and DSC =0.64 (right ventricle)]. After transfer learning with authentic data, the predictions achieved human level even for high undersampling rates (P = 33, DSC = 0.95, 0.87, and 0.93) without significant difference compared with segmentations derived from fully sampled data. Conclusion A 3D U-Net architecture can be used for semantic segmentation of radially undersampled cine acquisitions, achieving a performance comparable with human experts in fully sampled data. This approach can jointly accelerate time-consuming cine image acquisition and cumbersome manual image analysis.},
  language  = {en}
}
@article{HennesHuflageGrunzetal.2023,
  author    = {Hennes, Jan-Lucca and Huflage, Henner and Grunz, Jan-Peter and Hartung, Viktor and Augustin, Anne Marie and Patzer, Theresa Sophie and Pannenbecker, Pauline and Petritsch, Bernhard and Bley, Thorsten Alexander and Gruschwitz, Philipp},
  title     = {An intra-individual comparison of low-keV photon-counting CT versus energy-integrating-detector CT angiography of the aorta},
  series = {Diagnostics},
  volume    = {13},
  journal   = {Diagnostics},
  number    = {24},
  issn      = {2075-4418},
  doi       = {10.3390/diagnostics13243645},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-355568},
  year      = {2023},
  abstract  = {This retrospective study aims to provide an intra-individual comparison of aortic CT angiographies (CTAs) using first-generation photon-counting-detector CT (PCD-CT) and third-generation energy-integrating-detector CT (EID-CT). High-pitch CTAs were performed with both scanners and equal contrast-agent protocols. EID-CT employed automatic tube voltage selection (90/100 kVp) with reference tube current of 434/350 mAs, whereas multi-energy PCD-CT scans were generated with fixed tube voltage (120 kVp), image quality level of 64, and reconstructed as 55 keV monoenergetic images. For image quality assessment, contrast-to-noise ratios (CNRs) were calculated, and subjective evaluation (overall quality, luminal contrast, vessel sharpness, blooming, and beam hardening) was performed independently by three radiologists. Fifty-seven patients (12 women, 45 men) were included with a median interval between examinations of 12.7 months (interquartile range 11.1 months). Using manufacturer-recommended scan protocols resulted in a substantially lower radiation dose in PCD-CT (size-specific dose estimate: 4.88 ± 0.48 versus 6.28 ± 0.50 mGy, p < 0.001), while CNR was approximately 50\% higher (41.11 ± 8.68 versus 27.05 ± 6.73, p < 0.001). Overall image quality and luminal contrast were deemed superior in PCD-CT (p < 0.001). Notably, EID-CT allowed for comparable vessel sharpness (p = 0.439) and less pronounced blooming and beam hardening (p < 0.001). Inter-rater agreement was good to excellent (0.58-0.87). Concluding, aortic PCD-CTAs facilitate increased image quality with significantly lower radiation dose compared to EID-CTAs},
  language  = {en}
}
@article{GrunzKunzBaumannetal.2023,
  author    = {Grunz, Jan-Peter and Kunz, Andreas Steven and Baumann, Freerk T. and Hasenclever, Dirk and Sieren, Malte Maria and Heldmann, Stefan and Bley, Thorsten Alexander and Einsele, Hermann and Knop, Stefan and Jundt, Franziska},
  title     = {Assessing osteolytic lesion size on sequential CT scans is a reliable study endpoint for bone remineralization in newly diagnosed multiple myeloma},
  series = {Cancers},
  volume    = {15},
  journal   = {Cancers},
  number    = {15},
  issn      = {2072-6694},
  doi       = {10.3390/cancers15154008},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362526},
  year      = {2023},
  abstract  = {Multiple myeloma (MM) frequently induces persisting osteolytic manifestations despite hematologic treatment response. This study aimed to establish a biometrically valid study endpoint for bone remineralization through quantitative and qualitative analyses in sequential CT scans. Twenty patients (seven women, 58 ± 8 years) with newly diagnosed MM received standardized induction therapy comprising the anti-SLAMF7 antibody elotuzumab, carfilzomib, lenalidomide, and dexamethasone (E-KRd). All patients underwent whole-body low-dose CT scans before and after six cycles of E-KRd. Two radiologists independently recorded osteolytic lesion sizes, as well as the presence of cortical destruction, pathologic fractures, rim and trabecular sclerosis. Bland-Altman analyses and Krippendorff's α were employed to assess inter-reader reliability, which was high for lesion size measurement (standard error 1.2 mm) and all qualitative criteria assessed (α ≥ 0.74). After six cycles of E-KRd induction, osteolytic lesion size decreased by 22\% (p \&lt; 0.001). While lesion size response did not correlate with the initial lesion size at baseline imaging (Pearson's r = 0.144), logistic regression analysis revealed that the majority of responding osteolyses exhibited trabecular sclerosis (p \&lt; 0.001). The sum of osteolytic lesion sizes on sequential CT scans defines a reliable study endpoint to characterize bone remineralization. Patient level response is strongly associated with the presence of trabecular sclerosis.},
  language  = {en}
}
@article{AugustinWolfschmidtElsaesseretal.2022,
  author    = {Augustin, Anne Marie and Wolfschmidt, Franziska and Els{\"a}sser, Thilo and Sauer, Alexander and Dierks, Alexander and Bley, Thorsten Alexander and Kickuth, Ralph},
  title     = {Color-coded summation images for the evaluation of blood flow in endovascular aortic dissection fenestration},
  series = {BMC Medical Imaging},
  volume    = {22},
  journal   = {BMC Medical Imaging},
  number    = {1},
  doi       = {10.1186/s12880-022-00744-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301107},
  year      = {2022},
  abstract  = {Background To analyze the benefit of color-coded summation images in the assessment of target lumen perfusion in patients with aortic dissection and malperfusion syndrome before and after fluoroscopy-guided aortic fenestration. Methods Between December 2011 and April 2020 25 patients with Stanford type A (n = 13) or type B dissection (n = 12) and malperfusion syndromes were treated with fluoroscopy-guided fenestration of the dissection flap using a re-entry catheter. The procedure was technically successful in 100\% of the cases and included additional iliofemoral stent implantation in four patients. Intraprocedural systolic blood pressure measurements for gradient evaluation were performed in 19 cases. Post-processed color-coded DSA images were obtained from all DSA series before and following fenestration. Differences in time to peak (dTTP) values in the compromised aortic lumen and transluminal systolic blood pressure gradients were analyzed retrospectively. Correlation analysis between dTTP and changes in blood pressure gradients was performed. Results Mean TTP prior to dissection flap fenestration was 6.85 ± 1.35 s. After fenestration, mean TTP decreased significantly to 4.96 ± 0.94 s (p < 0.001). Available systolic blood pressure gradients between the true and the false lumen were reduced by a median of 4.0 mmHg following fenestration (p = 0.031), with significant reductions in Stanford type B dissections (p = 0.013) and minor reductions in type A dissections (p = 0.530). A moderate correlation with no statistical significance was found between dTTP and the difference in systolic blood pressure (r = 0.226; p = 0.351). Conclusions Hemodynamic parameters obtained from color-coded DSA confirmed a significant reduction of TTP values in the aortic target lumen in terms of an improved perfusion in the compromised aortic region. Color-coded DSA might thus be a suitable complementary tool in the assessment of complex vascular patterns prevailing in aortic dissections, especially when blood pressure measurements are not conclusive or feasible.},
  language  = {en}
}
@article{AugustinWelschBleyetal.2021,
  author    = {Augustin, Anne Marie and Welsch, Stefan and Bley, Thorsten Alexander and Lopau, Kai and Kickuth, Ralph},
  title     = {Color-coded summation images in the evaluation of renal artery stenosis before and after percutaneous transluminal angioplasty},
  series = {BMC Medical Imaging},
  volume    = {21},
  journal   = {BMC Medical Imaging},
  number    = {1},
  doi       = {10.1186/s12880-020-00540-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259086},
  pages     = {21},
  year      = {2021},
  abstract  = {Background: Endovascular therapy is the gold standard in patients with hemodynamic relevant renal artery stenosis (RAS) resistant to medical therapy. The severity grading of the stenosis as well as the result assessment after endovascular approach is predominantly based on visible estimations of the anatomic appearance. We aim to investigate the application of color-coded DSA parameters to gain hemodynamic information during endovascular renal artery interventions and for the assessment of the procedures technical success. Methods: We retrospectively evaluated 32 patients who underwent endovascular renal artery revascularization and applied color-coded summation imaging on selected monochromatic DSA images. The differences in time to peak (dTTP) of contrast enhancement in predefined anatomical measuring points were analyzed. Furthermore, differences in systolic blood pressure values (SBP) and serum creatinine were obtained. The value of underlying diabetes mellitus as a predictor for clinical outcome was assessed. Correlation analysis between the patients gender as well as the presence of diabetes mellitus and dTTP was performed. Results: Endovascular revascularization resulted in statistically significant improvement in 4/7 regions of interest. Highly significant improvement of perfusion in terms of shortened TTP values could be found at the segmental artery level and in the intrastenotical segment (p<0.001), significant improvement prestenotical and in the apical renal parenchyma (p<0.05). In the other anatomic regions, differences revealed not to be significant. Differences between SBP and serum creatinine levels before and after the procedure were significant (p=0.004 and 0.0004). Patients ' gender as well as the presence of diabetes mellitus did not reveal to be predictors for the clinical success of the procedure. Furthermore, diabetes and gender did not show relevant correlation with dTTP in the parenchymal measuring points. Conclusions: The supplementary use of color-coding DSA and the data gained from parametric images may provide helpful information in the evaluation of the procedures ' technical success. The segmental artery might be a particularly suitable vascular territory for analyzing differences in blood flow characteristics. Further studies with larger cohorts are needed to further confirm the diagnostic value of this technique.},
  language  = {en}
}
@article{GruschwitzHartungErguenetal.2023,
  author    = {Gruschwitz, Philipp and Hartung, Viktor and Erg{\"u}n, S{\"u}leyman and Peter, Dominik and Lichthardt, Sven and Huflage, Henner and Hendel, Robin and Pannenbecker, Pauline and Augustin, Anne Marie and Kunz, Andreas Steven and Feldle, Philipp and Bley, Thorsten Alexander and Grunz, Jan-Peter},
  title     = {Comparison of ultrahigh and standard resolution photon-counting CT angiography of the femoral arteries in a continuously perfused in vitro model},
  series = {European Radiology Experimental},
  volume    = {7},
  journal   = {European Radiology Experimental},
  doi       = {10.1186/s41747-023-00398-x},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357905},
  year      = {2023},
  abstract  = {Background With the emergence of photon-counting CT, ultrahigh-resolution (UHR) imaging can be performed without dose penalty. This study aims to directly compare the image quality of UHR and standard resolution (SR) scan mode in femoral artery angiographies. Methods After establishing continuous extracorporeal perfusion in four fresh-frozen cadaveric specimens, photon-counting CT angiographies were performed with a radiation dose of 5 mGy and tube voltage of 120 kV in both SR and UHR mode. Images were reconstructed with dedicated convolution kernels (soft: Body-vascular (Bv)48; sharp: Bv60; ultrasharp: Bv76). Six radiologists evaluated the image quality by means of a pairwise forced-choice comparison tool. Kendall's concordance coefficient (W) was calculated to quantify interrater agreement. Image quality was further assessed by measuring intraluminal attenuation and image noise as well as by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR). Results UHR yielded lower noise than SR for identical reconstructions with kernels ≥ Bv60 (p < 0.001). UHR scans exhibited lower intraluminal attenuation compared to SR (Bv60: 406.4 ± 25.1 versus 418.1 ± 30.1 HU; p < 0.001). Irrespective of scan mode, SNR and CNR decreased while noise increased with sharper kernels but UHR scans were objectively superior to SR nonetheless (Bv60: SNR 25.9 ± 6.4 versus 20.9 ± 5.3; CNR 22.7 ± 5.8 versus 18.4 ± 4.8; p < 0.001). Notably, UHR scans were preferred in subjective assessment when images were reconstructed with the ultrasharp Bv76 kernel, whereas SR was rated superior for Bv60. Interrater agreement was high (W = 0.935). Conclusions Combinations of UHR scan mode and ultrasharp convolution kernel are able to exploit the full image quality potential in photon-counting CT angiography of the femoral arteries. Relevance statement The UHR scan mode offers improved image quality and may increase diagnostic accuracy in CT angiography of the peripheral arterial runoff when optimized reconstruction parameters are chosen. Key points • UHR photon-counting CT improves image quality in combination with ultrasharp convolution kernels. • UHR datasets display lower image noise compared with identically reconstructed standard resolution scans. • Scans in UHR mode show decreased intraluminal attenuation compared with standard resolution imaging.},
  language  = {en}
}
@article{GruschwitzHartungKleefeldtetal.2023,
  author    = {Gruschwitz, Philipp and Hartung, Viktor and Kleefeldt, Florian and Peter, Dominik and Lichthardt, Sven and Huflage, Henner and Grunz, Jan-Peter and Augustin, Anne Marie and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Petritsch, Bernhard},
  title     = {Continuous extracorporeal femoral perfusion model for intravascular ultrasound, computed tomography and digital subtraction angiography},
  series = {PLoS One},
  volume    = {18},
  journal   = {PLoS One},
  number    = {5},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0285810},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350136},
  year      = {2023},
  abstract  = {Objectives We developed a novel human cadaveric perfusion model with continuous extracorporeal femoral perfusion suitable for performing intra-individual comparison studies, training of interventional procedures and preclinical testing of endovascular devices. Objective of this study was to introduce the techniques and evaluate the feasibility for realistic computed tomography angiography (CTA), digital subtraction angiography (DSA) including vascular interventions, and intravascular ultrasound (IVUS). Methods The establishment of the extracorporeal perfusion was attempted using one formalin-fixed and five fresh-frozen human cadavers. In all specimens, the common femoral and popliteal arteries were prepared, introducer sheaths inserted, and perfusion established by a peristaltic pump. Subsequently, we performed CTA and bilateral DSA in five cadavers and IVUS on both legs of four donors. Examination time without unintentional interruption was measured both with and without non-contrast planning CT. Percutaneous transluminal angioplasty and stenting was performed by two interventional radiologists on nine extremities (five donors) using a broad spectrum of different intravascular devices. Results The perfusion of the upper leg arteries was successfully established in all fresh-frozen but not in the formalin-fixed cadaver. The experimental setup generated a stable circulation in each procedure (ten upper legs) for a period of more than six hours. Images acquired with CT, DSA and IVUS offered a realistic impression and enabled the sufficient visualization of all examined vessel segments. Arterial cannulating, percutaneous transluminal angioplasty as well as stent deployment were feasible in a way that is comparable to a vascular intervention in vivo. The perfusion model allowed for introduction and testing of previously not used devices. Conclusions The continuous femoral perfusion model can be established with moderate effort, works stable, and is utilizable for medical imaging of the peripheral arterial system using CTA, DSA and IVUS. Therefore, it appears suitable for research studies, developing skills in interventional procedures and testing of new or unfamiliar vascular devices.},
  language  = {en}
}
@article{KraemerBeckerBleyetal.2022,
  author    = {Kraemer, Markus and Becker, Jana and Bley, Thorsten Alexander and Steinbrecher, Andreas and Minnerup, Jens and Hellmich, Bernhard},
  title     = {Diagnostik und Therapie der Riesenzellarteriitis},
  series = {Der Nervenarzt},
  volume    = {93},
  journal   = {Der Nervenarzt},
  number    = {8},
  issn      = {0028-2804},
  doi       = {10.1007/s00115-021-01216-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-307771},
  pages     = {819-827},
  year      = {2022},
  abstract  = {Die Riesenzellarteriitis (RZA) ist in der Altersgruppe der {\"u}ber 50-J{\"a}hrigen die h{\"a}ufigste idiopathische systemische Vaskulitis. Die Erkrankung bedarf einer zeitnahen Diagnostik und Therapie, um schwere Komplikationen wie eine Erblindung oder einen Schlaganfall zu vermeiden. Die Rezidivneigung erfordert eine mehrj{\"a}hrige, zum Teil lebenslange Glukokortikoid(GC)-Therapie, was das Risiko GC-induzierter Langzeitnebenwirkungen erh{\"o}ht. Daher wird bei der Mehrzahl der Patienten eine additive GC-einsparende Therapie empfohlen. Hierzu steht der Anti-IL-6-Rezeptor-Antik{\"o}rper Tocilizumab in subkutaner Applikation als zugelassene Substanz zur Verf{\"u}gung, alternativ kann Methotrexat (MTX) eingesetzt werden (off-label).},
  language  = {de}
}