@phdthesis{Conrads2020,
  author    = {Conrads, Nora},
  title     = {Auswertung der Schraubenposition nach navigierter, O-Arm-kontrollierter spinaler Instrumentierung},
  doi       = {10.25972/OPUS-21714},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217147},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {In dieser Studie wurden retrospektiv zwischen Juni 2010 und Juni 2015 die Schrauben bez{\"u}glich ihrer Lage und L{\"a}nge nach navigierter, O-Arm kontrollierter dorsaler Stabilisierung der Wirbels{\"a}ule untersucht. In diesem Zeitraum wurden in der Neurochirurgie des Universit{\"a}tsklinikums W{\"u}rzburg 2666 Schrauben bei 433 Patienten in 413 Operationen platziert, wobei 2618 Schrauben in dieser Studie ausgewertet werden konnten. Gr{\"u}nde f{\"u}r eine operative Stabilisierung der Wirbels{\"a}ule waren im Gesamtkollektiv mit 58,43\% am h{\"a}ufigsten degenerative Ver{\"a}nderungen gefolgt von Traumata mit 21,94\%, Tumorerkrankungen mit 11,78\% und entz{\"u}ndlichen Ver{\"a}nderungen mit 7,85\%. Im Bereich der HWS waren die h{\"a}ufigsten Operationsindikationen traumatische Verletzungen mit 46,06\%, auf H{\"o}he der BWS Tumordiagnosen mit 46,77\% und im Bereich der LWS degenerative Ver{\"a}nderungen mit 76,82\%. Die Schrauben wurden auf H{\"o}he der BWS und LWS bez{\"u}glich ihrer Lage nach der etablierten Einteilung von Zdichavsky et al. klassifiziert. Die Grundlage dieser Klassifikation ist die Relation der Pedikelschraube zum Pedikel und die Relation der Pedikelschraube zum Wirbelk{\"o}rper, wobei eine korrekte 1a-Lage vorliegt, wenn mindestens die H{\"a}lfte des Pedikelschraubendurchmessers innerhalb des Pedikels und mindestens die H{\"a}lfte des Pedikelschraubendurchmessers innerhalb des Wirbelk{\"o}rpers liegt. Im Bereich der BWS lagen bereits nach dem ersten intraoperativen Scan 89,72\% der Schrauben in einer 1a-Lage, nach intraoperativer Revision von 41 Schrauben sogar 93,03\% der Schrauben. Auf H{\"o}he der LWS lagen nach dem 1. intraoperativen Scan 94,88\% in einer 1a-Lage, nach intraoperativer Revision von 37 Schrauben konnte der Anteil an 1a-Lagen auf 96,14\% erh{\"o}ht werden. In Anlehnung an die Klassifikation von Zdichavsky et al. entstand eine neue Klassifikation f{\"u}r die HWS mit der {\"U}berlegung, dass die Stabilit{\"a}t und die Gefahr f{\"u}r neurologische und vaskul{\"a}re Komplikationen durch die Lage der Schrauben im Knochen definiert werden kann. Auch hier liegt eine korrekte 1a-Lage vor, wenn mindestens die H{\"a}lfte des Schraubendurchmessers innerhalb des Pedikels bzw. der Massa lateralis verl{\"a}uft. Nach dem ersten intraoperativen Scan lagen bereits 93,93\% der Schrauben in einer 1a-Lage, nach intraoperativer Revision von 32 Schrauben lagen sogar 96,20\% der Schrauben in einer 1a-Lage. Die Bewertung der Schraubl{\"a}nge erfolgte relativ zur L{\"a}nge des Schraubeneintrittspunkts und der Vorderkante des Wirbelk{\"o}rpers, wobei alle Schraubenl{\"a}ngen zwischen 85\% und 100\% als „gut" eingestuft wurden. Im Bereich der HWS hatten demnach zu Operationsende 65,62\% der Schrauben eine gute Lange, in der BWS 69,72\% und in der LWS 71,92\%. Aufgrund einer prim{\"a}ren Fehllage mussten lediglich 2 Schrauben (0,08\% aller Schrauben) bei einem Patienten in einer Folgeoperation revidiert werden, wobei diese Fehllage retrospektiv auch in der initialen intraoperativen Bildgebung h{\"a}tte erkannt werden k{\"o}nnen. Weitere Parameter wie Operationsdauer und Operationsart, Anzahl an intraoperativer Bildgebung sowie Anzahl der verschraubten Wirbelsegmente oder intraoperative Komplikationen wurden untersucht. In der klinischen Verlaufskontrolle zeigte sich außerdem eine signifikante Verbesserung der Schmerzen, n{\"a}mlich in jeder Kategorie (Bein-, Arm-, R{\"u}cken-, Nackenschmerzen) gaben mindestens 75\% der nachkontrollierten Patienten eine Komplettremission oder relevante Verbesserung der Symptome an. Auch in der neurologischen Verlaufskontrolle zeigte sich bei 68,86\% der Patienten in der Nachkontrolle eine Komplettremission bzw. signifikante Verbesserung der neurologischen Beschwerden. In der postoperativen radiologischen Abschlussuntersuchung zeigten sich lediglich bei 3,07\% der Schrauben Auff{\"a}lligkeiten in Form von Schraubenlockerung (2,40\%), Schraubendislokation (0,49\%) oder Schraubenbr{\"u}chen (0,19\%).},
  subject      = {Neurochirurgie},
  language  = {de}
}
@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{HuflageKarstenKunzetal.2021,
  author    = {Huflage, Henner and Karsten, Sebastian and Kunz, Andreas Steven and Conrads, Nora and Jakubietz, Rafael Gregor and Jakubietz, Michael Georg and Pennig, Lenhard and Goertz, Lukas and Bley, Thorsten Alexander and Schmitt, Rainer and Grunz, Jan-Peter},
  title     = {Improved diagnostic accuracy for ulnar-sided TFCC lesions with radial reformation of 3D sequences in wrist MR arthrography},
  series = {European Radiology},
  volume    = {31},
  journal   = {European Radiology},
  number    = {12},
  issn      = {1432-1084},
  doi       = {10.1007/s00330-021-08024-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-266512},
  pages     = {9399-9407},
  year      = {2021},
  abstract  = {Objectives Triangular fibrocartilage complex (TFCC) injuries frequently cause ulnar-sided wrist pain and can induce distal radioulnar joint instability. With its complex three-dimensional structure, diagnosis of TFCC lesions remains a challenging task even in MR arthrograms. The aim of this study was to assess the added diagnostic value of radial reformatting of isotropic 3D MRI datasets compared to standard planes after direct arthrography of the wrist. Methods Ninety-three patients underwent wrist MRI after fluoroscopy-guided multi-compartment arthrography. Two radiologists collectively analyzed two datasets of each MR arthrogram for TFCC injuries, with one set containing standard reconstructions of a 3D thin-slice sequence in axial, coronal and sagittal orientation, while the other set comprised an additional radial plane view with the rotating center positioned at the ulnar styloid. Surgical reports (whenever available) or radiological reports combined with clinical follow-up served as a standard of reference. In addition, diagnostic confidence and assessability of the central disc and ulnar-sided insertions were subjectively evaluated. Results Injuries of the articular disc, styloid and foveal ulnar attachment were present in 20 (23.7\%), 10 (10.8\%) and 9 (9.7\%) patients. Additional radial planes increased diagnostic accuracy for lesions of the styloid (0.83 vs. 0.90; p = 0.016) and foveal (0.86 vs. 0.94; p = 0.039) insertion, whereas no improvement was identified for alterations of the central cartilage disc. Readers' confidence (p < 0.001) and assessability of the ulnar-sided insertions (p < 0.001) were superior with ancillary radial reformatting. Conclusions Access to the radial plane view of isotropic 3D sequences in MR arthrography improves diagnostic accuracy and confidence for ulnar-sided TFCC lesions.},
  language  = {en}
}
@article{ConradsGrunzHuflageetal.2023,
  author    = {Conrads, Nora and Grunz, Jan-Peter and Huflage, Henner and Luetkens, Karsten Sebastian and Feldle, Philipp and Grunz, Katharina and K{\"o}hler, Stefan and Westermaier, Thomas},
  title     = {Accuracy of pedicle screw placement using neuronavigation based on intraoperative 3D rotational fluoroscopy in the thoracic and lumbar spine},
  series = {Archives of Orthopaedic and Trauma Surgery},
  volume    = {143},
  journal   = {Archives of Orthopaedic and Trauma Surgery},
  number    = {6},
  doi       = {10.1007/s00402-022-04514-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324966},
  pages     = {3007-3013},
  year      = {2023},
  abstract  = {Introduction In spinal surgery, precise instrumentation is essential. This study aims to evaluate the accuracy of navigated, O-arm-controlled screw positioning in thoracic and lumbar spine instabilities. Materials and methods Posterior instrumentation procedures between 2010 and 2015 were retrospectively analyzed. Pedicle screws were placed using 3D rotational fluoroscopy and neuronavigation. Accuracy of screw placement was assessed using a 6-grade scoring system. In addition, screw length was analyzed in relation to the vertebral body diameter. Intra- and postoperative revision rates were recorded. Results Thoracic and lumbar spine surgery was performed in 285 patients. Of 1704 pedicle screws, 1621 (95.1\%) showed excellent positioning in 3D rotational fluoroscopy imaging. The lateral rim of either pedicle or vertebral body was protruded in 25 (1.5\%) and 28 screws (1.6\%), while the midline of the vertebral body was crossed in 8 screws (0.5\%). Furthermore, 11 screws each (0.6\%) fulfilled the criteria of full lateral and medial displacement. The median relative screw length was 92.6\%. Intraoperative revision resulted in excellent positioning in 58 of 71 screws. Follow-up surgery due to missed primary malposition had to be performed for two screws in the same patient. Postsurgical symptom relief was reported in 82.1\% of patients, whereas neurological deterioration occurred in 8.9\% of cases with neurological follow-up. Conclusions Combination of neuronavigation and 3D rotational fluoroscopy control ensures excellent accuracy in pedicle screw positioning. As misplaced screws can be detected reliably and revised intraoperatively, repeated surgery for screw malposition is rarely required.},
  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{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}
}