@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{VeldhoenBehzadiLenzetal.2017, author = {Veldhoen, Simon and Behzadi, Cyrus and Lenz, Alexander and Henes, Frank Oliver and Rybczynski, Meike and von Kodolitsch, Yskert and Bley, Thorsten Alexander and Adam, Gerhard and Bannas, Peter}, title = {Non-contrast MR angiography at 1.5 Tesla for aortic monitoring in Marfan patients after aortic root surgery}, series = {Journal of Cardiovascular Magnetic Resonance}, volume = {19}, journal = {Journal of Cardiovascular Magnetic Resonance}, number = {82}, doi = {10.1186/s12968-017-0394-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158693}, year = {2017}, abstract = {Background: Contrast-enhanced cardiovascular magnetic resonance angiography (CE-CMRA) is the established imaging modality for patients with Marfan syndrome requiring life-long annual aortic imaging before and after aortic root replacement. Contrast-free CMRA techniques avoiding side-effects of contrast media are highly desirable for serial imaging but have not been evaluated in the postoperative setup of Marfan patients. The purpose of this study was to assess the feasibility of non-contrast balanced steady-state free precession (bSSFP) magnetic resonance imaging for aortic monitoring of postoperative patients with Marfan syndrome. Methods: Sixty-four adult Marfan patients after aortic root replacement were prospectively included. Fourteen patients (22\%) had a residual aortic dissection after surgical treatment of type A dissection. bSSFP imaging and CE-CMRA were performed at 1.5 Tesla. Two radiologists evaluated the images regarding image quality (1 = poor, 4 = excellent), artifacts (1 = severe, 4 = none) and aortic pathologies. Readers measured the aortic diameters at defined levels in both techniques. Statistics included observer agreement for image scoring and diameter measurements and ROC analyses for comparison of the diagnostic performance of bSSFP and CE-CMRA. Results: Both readers observed no significant differences in image quality between bSSFP and CE-CMRA and found a median image quality score of 4 for both techniques (all p > .05). No significant differences were found regarding the frequency of image artifacts in both sequences (all p > .05). Sensitivity and specificity for detection of aortic dissections was 100\% for both readers and techniques. Compared to bSSFP imaging, CE-CMRA resulted in higher diameters (mean bias, 0.9 mm; p < .05). The inter-observer biases of diameter measurements were not significantly different (all p > .05), except for the distal graft anastomosis (p = .001). Using both techniques, the readers correctly identified a graft suture dehiscence with aneurysm formation requiring surgery. Conclusion: Unenhanced bSSFP CMR imaging allows for riskless aortic monitoring with high diagnostic accuracy in Marfan patients after aortic root surgery.}, language = {en} } @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{ReichelHerzelTabbakhetal.2021, author = {Reichel, Thomas and Herz, Stefan and el Tabbakh, Mohammed and Bley, Thorsten Alexander and Plumhoff, Piet and Rueckl, Kilian}, title = {Less than 9.5-mm coracohumeral distance on axial magnetic resonance imaging scans predicts for subscapularis tear}, series = {JSES International}, volume = {5}, journal = {JSES International}, number = {3}, doi = {10.1016/j.jseint.2021.01.014}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259118}, pages = {424-429}, year = {2021}, abstract = {Background Diagnosis of subscapularis (SSC) tendon lesions on magnetic resonance imaging (MRI) can be challenging. A small coracohumeral distance (CHD) has been associated with SSC tears. This study was designed to define a specific threshold value for CHD to predict SSC tears on axial MRI scans. Methods This retrospective study included 172 shoulders of 168 patients who underwent arthroscopic surgery for rotator cuff tear or glenohumeral instability. Diagnostic arthroscopy confirmed an SSC tear in 62 cases (36.0\%, test group a), rotator cuff tear tears other than SSC in 71 cases (41.3\%, control group b) and glenohumeral instability without any rotator cuff tear in 39 cases (22.7\%, zero-sample group c). All patients had a preoperative MRI of the shoulder (1.5T or 3T). Minimum CHD was measured on axial fat-suppressed proton density-, T2-, or T1-weigthed sequences. Receiver operating characteristics analysis was used to determine the threshold value for CHD, and sensitivity and specificity were calculated. Results CHD measurement had a good interobserver reliability (Intraclass correlation coefficient 0.799). Mean CHD was highly significantly (P < .001) less for test group a (mean 7.3 mm, standard deviation ± 2.2) compared with control group b (mean 11.1 mm, standard deviation ± 2.3) or zero-sample group c (mean 13.6 mm, standard deviation ± 2.9). A threshold value of CHD <9.5 mm had a sensitivity of 83.6\% and a specificity of 83.9\% to predict SSC tears. Conclusion A CHD <9.5 mm on MRI is predictive of SSC lesions and a valuable tool to diagnose SSC tears.}, language = {en} } @article{PetritschKosmalaWengetal.2019, author = {Petritsch, Berhard and Kosmala, Aleksander and Weng, Andreas Max and Bley, Thorsten Alexander}, title = {Tin-filtered 100kV ultra-low-dose CT of the paranasal sinus: initial clinical results}, series = {PLoS ONE}, volume = {14}, journal = {PLoS ONE}, number = {5}, doi = {10.1371/ journal.pone.0216295}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204127}, pages = {e0216295}, year = {2019}, abstract = {Objectives To investigate the feasibility, diagnostic image quality and radiation dose of 3\(^{rd}\) generation dual-source computed tomography (CT) using a tin-filtered 100 kV protocol in patients with suspected acute inflammatory sinus disease. Methods We retrospectively evaluated 109 consecutive patients who underwent CT (Siemens SOMATOM Force, Erlangen, Germany) of the paranasal sinus with a new tin-filtered scanprotocol (Sn100 kV; tube current 35 mAs) using iterative reconstruction. Two readers independently assessed subjective image quality using a five-point Likert scale (1 = excellent, 5 = non-diagnostic). Inter-observer agreement was calculated and expressed as percentage of agreement. Noise was determined for calculation of signal-to-noise-ratio (SNR). Effective radiation dose (ED) was calculated from the dose-length-product (DLP). Results All examinations showed diagnostic image quality regarding evaluation of inflammatory sinus disease. On average, subjective general image quality was rated moderate (= 3) with a percentage of agreement between the observers of 81\%. The mean image noise was 14.3 HU. The calculated median SNR was 6.0 for intraorbital fat, and 3.6 for the vitreous body, respectively. The median DLP was 2.1 mGy*cm, resulting in a median ED of 0.012 mSv. Conclusions Taking the study limitations into account, ultra-low-dose tin-filtered CT of the paranasal sinus at a tube voltage of 100 kV utilizing an iterative reconstruction algorithm provides for reliable exclusion of suspected acute inflammatory sinus disease in 100\% of the cases.}, 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} } @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{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{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} } @article{HuflageKunzHendeletal.2023, author = {Huflage, Henner and Kunz, Andreas Steven and Hendel, Robin and Kraft, Johannes and Weick, Stefan and Razinskas, Gary and Sauer, Stephanie Tina and Pennig, Lenhard and Bley, Thorsten Alexander and Grunz, Jan-Peter}, title = {Obesity-related pitfalls of virtual versus true non-contrast imaging — an intraindividual comparison in 253 oncologic patients}, series = {Diagnostics}, volume = {13}, journal = {Diagnostics}, number = {9}, issn = {2075-4418}, doi = {10.3390/diagnostics13091558}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313519}, year = {2023}, abstract = {Objectives: Dual-source dual-energy CT (DECT) facilitates reconstruction of virtual non-contrast images from contrast-enhanced scans within a limited field of view. This study evaluates the replacement of true non-contrast acquisition with virtual non-contrast reconstructions and investigates the limitations of dual-source DECT in obese patients. Materials and Methods: A total of 253 oncologic patients (153 women; age 64.5 ± 16.2 years; BMI 26.6 ± 5.1 kg/m\(^2\)) received both multi-phase single-energy CT (SECT) and DECT in sequential staging examinations with a third-generation dual-source scanner. Patients were allocated to one of three BMI clusters: non-obese: <25 kg/m\(^2\) (n = 110), pre-obese: 25-29.9 kg/m\(^2\) (n = 73), and obese: >30 kg/m\(^2\) (n = 70). Radiation dose and image quality were compared for each scan. DECT examinations were evaluated regarding liver coverage within the dual-energy field of view. Results: While arterial contrast phases in DECT were associated with a higher CTDI\(_{vol}\) than in SECT (11.1 vs. 8.1 mGy; p < 0.001), replacement of true with virtual non-contrast imaging resulted in a considerably lower overall dose-length product (312.6 vs. 475.3 mGy·cm; p < 0.001). The proportion of DLP variance predictable from patient BMI was substantial in DECT (R\(^2\) = 0.738) and SECT (R\(^2\) = 0.620); however, DLP of SECT showed a stronger increase in obese patients (p < 0.001). Incomplete coverage of the liver within the dual-energy field of view was most common in the obese subgroup (17.1\%) compared with non-obese (0\%) and pre-obese patients (4.1\%). Conclusion: DECT facilitates a 30.8\% dose reduction over SECT in abdominal oncologic staging examinations. Employing dual-source scanner architecture, the risk for incomplete liver coverage increases in obese patients.}, language = {en} }