@article{JordanBroeerFischeretal.2022,
  author    = {Jordan, Martin C. and Br{\"o}er, David and Fischer, Christian and Heilig, Philipp and Gilbert, Fabian and H{\"o}lscher-Doht, Stefanie and Kalogirou, Charis and Popp, Kevin and Grunz, Jan-Peter and Huflage, Henner and Jakubietz, Rafael G. and Erg{\"u}n, S{\"u}leyman and Meffert, Rainer H.},
  title     = {Development and preclinical evaluation of a cable-clamp fixation device for a disrupted pubic symphysis},
  series = {Communications Medicine},
  volume    = {2},
  journal   = {Communications Medicine},
  number    = {1},
  doi       = {10.1038/s43856-022-00227-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-299800},
  year      = {2022},
  abstract  = {Background Traumatic separation of the pubic symphysis can destabilize the pelvis and require surgical fixation to reduce symphyseal gapping. The traditional approach involves open reduction and the implantation of a steel symphyseal plate (SP) on the pubic bone to hold the reposition. Despite its widespread use, SP-fixation is often associated with implant failure caused by screw loosening or breakage. Methods To address the need for a more reliable surgical intervention, we developed and tested two titanium cable-clamp implants. The cable served as tensioning device while the clamp secured the cable to the bone. The first implant design included a steel cable anterior to the pubic symphysis to simplify its placement outside the pelvis, and the second design included a cable encircling the pubic symphysis to stabilize the anterior pelvic ring. Using highly reproducible synthetic bone models and a limited number of cadaver specimens, we performed a comprehensive biomechanical study of implant stability and evaluated surgical feasibility. Results We were able to demonstrate that the cable-clamp implants provide stability equivalent to that of a traditional SP-fixation but without the same risks of implant failure. We also provide detailed ex vivo evaluations of the safety and feasibility of a trans-obturator surgical approach required for those kind of fixation. Conclusion We propose that the developed cable-clamp fixation devices may be of clinical value in treating pubic symphysis separation.},
  language  = {en}
}
@article{LuetkensErguenHuflageetal.2021,
  author    = {Luetkens, Karsten Sebastian and Erg{\"u}n, S{\"u}leyman and Huflage, Henner and Kunz, Andreas Steven and Gietzen, Carsten Herbert and Conrads, Nora and Pennig, Lenhard and Goertz, Lukas and Bley, Thorsten Alexander and Gassenmaier, Tobias and Grunz, Jan-Peter},
  title     = {Dose reduction potential in cone-beam CT imaging of upper extremity joints with a twin robotic x-ray system},
  series = {Scientific Reports},
  volume    = {11},
  journal   = {Scientific Reports},
  number    = {1},
  doi       = {10.1038/s41598-021-99748-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-270429},
  year      = {2021},
  abstract  = {Cone-beam computed tomography is a powerful tool for 3D imaging of the appendicular skeleton, facilitating detailed visualization of bone microarchitecture. This study evaluated various combinations of acquisition and reconstruction parameters for the cone-beam CT mode of a twin robotic x-ray system in cadaveric wrist and elbow scans, aiming to define the best possible trade-off between image quality and radiation dose. Images were acquired with different combinations of tube voltage and tube current-time product, resulting in five scan protocols with varying volume CT dose indices: full-dose (FD; 17.4 mGy), low-dose (LD; 4.5 mGy), ultra-low-dose (ULD; 1.15 mGy), modulated low-dose (mLD; 0.6 mGy) and modulated ultra-low-dose (mULD; 0.29 mGy). Each set of projection data was reconstructed with three convolution kernels (very sharp [Ur77], sharp [Br69], intermediate [Br62]). Five radiologists subjectively assessed the image quality of cortical bone, cancellous bone and soft tissue using seven-point scales. Irrespective of the reconstruction kernel, overall image quality of every FD, LD and ULD scan was deemed suitable for diagnostic use in contrast to mLD (very sharp/sharp/intermediate: 60/55/70\%) and mULD (0/3/5\%). Superior depiction of cortical and cancellous bone was achieved in FD\(_{Ur77}\) and LD\(_{Ur77}\) examinations (p < 0.001) with LD\(_{Ur77}\) scans also providing favorable bone visualization compared to FD\(_{Br69}\) and FD\(_{Br62}\) (p < 0.001). Fleiss' kappa was 0.618 (0.594-0.641; p < 0.001), indicating substantial interrater reliability. In this study, we demonstrate that considerable dose reduction can be realized while maintaining diagnostic image quality in upper extremity joint scans with the cone-beam CT mode of a twin robotic x-ray system. Application of sharper convolution kernels for image reconstruction facilitates superior display of bone microarchitecture.},
  language  = {en}
}
@article{GruschwitzHartungKleefeldtetal.2023,
  author    = {Gruschwitz, Philipp and Hartung, Viktor and Kleefeldt, Florian and Erg{\"u}n, S{\"u}leyman and Lichthardt, Sven and Huflage, Henner and Hendel, Robin and Kunz, Andreas Steven and Pannenbecker, Pauline and Kuhl, Philipp Josef and Augustin, Anne Marie and Bley, Thorsten Alexander and Petritsch, Bernhard and Grunz, Jan-Peter},
  title     = {Standardized assessment of vascular reconstruction kernels in photon-counting CT angiographies of the leg using a continuous extracorporeal perfusion model},
  series = {Scientific Reports},
  volume    = {13},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-023-39063-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357912},
  year      = {2023},
  abstract  = {This study evaluated the influence of different vascular reconstruction kernels on the image quality of CT angiographies of the lower extremity runoff using a 1st-generation photon-counting-detector CT (PCD-CT) compared with dose-matched examinations on a 3rd-generation energy-integrating-detector CT (EID-CT). Inducing continuous extracorporeal perfusion in a human cadaveric model, we performed CT angiographies of eight upper leg arterial runoffs with radiation dose-equivalent 120 kVp acquisition protocols (CTDIvol 5 mGy). Reconstructions were executed with different vascular kernels, matching the individual modulation transfer functions between scanners. Signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were computed to assess objective image quality. Six radiologists evaluated image quality subjectively using a forced-choice pairwise comparison tool. Interrater agreement was determined by calculating Kendall's concordance coefficient (W). The intraluminal attenuation of PCD-CT images was significantly higher than of EID-CT (414.7 ± 27.3 HU vs. 329.3 ± 24.5 HU; p < 0.001). Using comparable kernels, image noise with PCD-CT was significantly lower than with EID-CT (p ≤ 0.044). Correspondingly, SNR and CNR were approximately twofold higher for PCD-CT (p < 0.001). Increasing the spatial frequency for PCD-CT reconstructions by one level resulted in similar metrics compared to EID-CT (CNRfat; EID-CT Bv49: 21.7 ± 3.7 versus PCD-CT Bv60: 21.4 ± 3.5). Overall image quality of PCD-CTA achieved ratings superior to EID-CTA irrespective of the used reconstruction kernels (best: PCD-CT Bv60; worst: EID-CT Bv40; p < 0.001). Interrater agreement was good (W = 0.78). Concluding, PCD-CT offers superior intraluminal attenuation, SNR, and CNR compared to EID-CT in angiographies of the upper leg arterial runoff. Combined with improved subjective image quality, PCD-CT facilitates the use of sharper convolution kernels and ultimately bears the potential of improved vascular structure assessability.},
  language  = {en}
}
@article{PatzerKunzHuflageetal.2023,
  author    = {Patzer, Theresa Sophie and Kunz, Andreas Steven and Huflage, Henner and Conrads, Nora and Luetkens, Karsten Sebastian and Pannenbecker, Pauline and Paul, Mila Marie and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Grunz, Jan-Peter},
  title     = {Ultrahigh-resolution photon-counting CT in cadaveric fracture models: spatial frequency is not everything},
  series = {Diagnostics},
  volume    = {13},
  journal   = {Diagnostics},
  number    = {10},
  issn      = {2075-4418},
  doi       = {10.3390/diagnostics13101677},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-319281},
  year      = {2023},
  abstract  = {In this study, the impact of reconstruction sharpness on the visualization of the appendicular skeleton in ultrahigh-resolution (UHR) photon-counting detector (PCD) CT was investigated. Sixteen cadaveric extremities (eight fractured) were examined with a standardized 120 kVp scan protocol (CTDI\(_{vol}\) 10 mGy). Images were reconstructed with the sharpest non-UHR kernel (Br76) and all available UHR kernels (Br80 to Br96). Seven radiologists evaluated image quality and fracture assessability. Interrater agreement was assessed with the intraclass correlation coefficient. For quantitative comparisons, signal-to-noise-ratios (SNRs) were calculated. Subjective image quality was best for Br84 (median 1, interquartile range 1-3; p ≤ 0.003). Regarding fracture assessability, no significant difference was ascertained between Br76, Br80 and Br84 (p > 0.999), with inferior ratings for all sharper kernels (p < 0.001). Interrater agreement for image quality (0.795, 0.732-0.848; p < 0.001) and fracture assessability (0.880; 0.842-0.911; p < 0.001) was good. SNR was highest for Br76 (3.4, 3.0-3.9) with no significant difference to Br80 and Br84 (p > 0.999). Br76 and Br80 produced higher SNRs than all kernels sharper than Br84 (p ≤ 0.026). In conclusion, PCD-CT reconstructions with a moderate UHR kernel offer superior image quality for visualizing the appendicular skeleton. Fracture assessability benefits from sharp non-UHR and moderate UHR kernels, while ultra-sharp reconstructions incur augmented image noise.},
  language  = {en}
}
@article{HuflageGrunzPatzeretal.2023,
  author    = {Huflage, Henner and Grunz, Jan-Peter and Patzer, Theresa Sophie and Pannenbecker, Pauline and Feldle, Philipp and Sauer, Stephanie Tina and Petritsch, Bernhard and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Kunz, Andreas Steven},
  title     = {Potential of unenhanced ultra-low-dose abdominal photon-counting CT with tin filtration: a cadaveric study},
  series = {Diagnostics},
  volume    = {13},
  journal   = {Diagnostics},
  number    = {4},
  issn      = {2075-4418},
  doi       = {10.3390/diagnostics13040603},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304122},
  year      = {2023},
  abstract  = {Objectives: This study investigated the feasibility and image quality of ultra-low-dose unenhanced abdominal CT using photon-counting detector technology and tin prefiltration. Materials and Methods: Employing a first-generation photon-counting CT scanner, eight cadaveric specimens were examined both with tin prefiltration (Sn 100 kVp) and polychromatic (120 kVp) scan protocols matched for radiation dose at three different levels: standard-dose (3 mGy), low-dose (1 mGy) and ultra-low-dose (0.5 mGy). Image quality was evaluated quantitatively by means of contrast-to-noise-ratios (CNR) with regions of interest placed in the renal cortex and subcutaneous fat. Additionally, three independent radiologists performed subjective evaluation of image quality. The intraclass correlation coefficient was calculated as a measure of interrater reliability. Results: Irrespective of scan mode, CNR in the renal cortex decreased with lower radiation dose. Despite similar mean energy of the applied x-ray spectrum, CNR was superior for Sn 100 kVp over 120 kVp at standard-dose (17.75 ± 3.51 vs. 14.13 ± 4.02), low-dose (13.99 ± 2.6 vs. 10.68 ± 2.17) and ultra-low-dose levels (8.88 ± 2.01 vs. 11.06 ± 1.74) (all p ≤ 0.05). Subjective image quality was highest for both standard-dose protocols (score 5; interquartile range 5-5). While no difference was ascertained between Sn 100 kVp and 120 kVp examinations at standard and low-dose levels, the subjective image quality of tin-filtered scans was superior to 120 kVp with ultra-low radiation dose (p < 0.05). An intraclass correlation coefficient of 0.844 (95\% confidence interval 0.763-0.906; p < 0.001) indicated good interrater reliability. Conclusions: Photon-counting detector CT permits excellent image quality in unenhanced abdominal CT with very low radiation dose. Employment of tin prefiltration at 100 kVp instead of polychromatic imaging at 120 kVp increases the image quality even further in the ultra-low-dose range of 0.5 mGy.},
  language  = {en}
}
@article{PatzerKunzHuflageetal.2023,
  author    = {Patzer, Theresa Sophie and Kunz, Andreas Steven and Huflage, Henner and Luetkens, Karsten Sebastian and Conrads, Nora and Gruschwitz, Philipp and Pannenbecker, Pauline and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Grunz, Jan-Peter},
  title     = {Quantitative and qualitative image quality assessment in shoulder examinations with a first-generation photon-counting detector CT},
  series = {Scientific Reports},
  volume    = {13},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-023-35367-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357925},
  year      = {2023},
  abstract  = {Photon-counting detector (PCD) CT allows for ultra-high-resolution (UHR) examinations of the shoulder without requiring an additional post-patient comb filter to narrow the detector aperture. This study was designed to compare the PCD performance with a high-end energy-integrating detector (EID) CT. Sixteen cadaveric shoulders were examined with both scanners using dose-matched 120 kVp acquisition protocols (low-dose/full-dose: CTDI\(_{vol}\) = 5.0/10.0 mGy). Specimens were scanned in UHR mode with the PCD-CT, whereas EID-CT examinations were conducted in accordance with the clinical standard as "non-UHR". Reconstruction of EID data employed the sharpest kernel available for standard-resolution scans (ρ\(_{50}\) = 12.3 lp/cm), while PCD data were reconstructed with both a comparable kernel (11.8 lp/cm) and a sharper dedicated bone kernel (16.5 lp/cm). Six radiologists with 2-9 years of experience in musculoskeletal imaging rated image quality subjectively. Interrater agreement was analyzed by calculation of the intraclass correlation coefficient in a two-way random effects model. Quantitative analyses comprised noise recording and calculating signal-to-noise ratios based on attenuation measurements in bone and soft tissue. Subjective image quality was higher in UHR-PCD-CT than in EID-CT and non-UHR-PCD-CT datasets (all p < 0.001). While low-dose UHR-PCD-CT was considered superior to full-dose non-UHR studies on either scanner (all p < 0.001), ratings of low-dose non-UHR-PCD-CT and full-dose EID-CT examinations did not differ (p > 0.99). Interrater reliability was moderate, indicated by a single measures intraclass correlation coefficient of 0.66 (95\% confidence interval: 0.58-0.73; p < 0.001). Image noise was lowest and signal-to-noise ratios were highest in non-UHR-PCD-CT reconstructions at either dose level (p < 0.001). This investigation demonstrates that superior depiction of trabecular microstructure and considerable denoising can be realized without additional radiation dose by employing a PCD for shoulder CT imaging. Allowing for UHR scans without dose penalty, PCD-CT appears as a promising alternative to EID-CT for shoulder trauma assessment in clinical routine.},
  language  = {en}
}