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  • 1
    In: European Radiology, Springer Science and Business Media LLC, Vol. 29, No. 2 ( 2019-2), p. 1062-1062
    Type of Medium: Online Resource
    ISSN: 0938-7994 , 1432-1084
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 1472718-3
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  • 2
    In: European Radiology, Springer Science and Business Media LLC, Vol. 31, No. 9 ( 2021-09), p. 7151-7161
    Abstract: To evaluate the reduction of artifacts from cardiac implantable electronic devices (CIEDs) by virtual monoenergetic images (VMI), metal artifact reduction (MAR) algorithms, and their combination (VMI MAR ) derived from spectral detector CT (SDCT) of the chest compared to conventional CT images (CI). Methods In this retrospective study, we included 34 patients (mean age 74.6 ± 8.6 years), who underwent a SDCT of the chest and had a CIED in place. CI, MAR, VMI, and VMI MAR (10 keV increment, range: 100–200 keV) were reconstructed. Mean and standard deviation of attenuation (HU) among hypo- and hyperdense artifacts adjacent to CIED generator and leads were determined using ROIs. Two radiologists qualitatively evaluated artifact reduction and diagnostic assessment of adjacent tissue. Results Compared to CI, MAR and VMI MAR ≥ 100 keV significantly increased attenuation in hypodense and significantly decreased attenuation in hyperdense artifacts at CIED generator and leads ( p 〈 0.05). VMI ≥ 100 keV alone only significantly decreased hyperdense artifacts at the generator ( p 〈 0.05). Qualitatively, VMI ≥ 100 keV, MAR, and VMI MAR ≥ 100 keV provided significant reduction of hyper- and hypodense artifacts resulting from the generator and improved diagnostic assessment of surrounding structures ( p 〈 0.05). Diagnostic assessment of structures adjoining to the leads was only improved by MAR and VMI MAR 100 keV ( p 〈 0.05), whereas keV values ≥ 140 with and without MAR significantly worsened diagnostic assessment ( p 〈 0.05). Conclusions The combination of VMI and MAR as well as MAR as a standalone approach provides effective reduction of artifacts from CIEDs. Still, higher keV values should be applied with caution due to a loss of soft tissue and vessel contrast along the leads. Key Points • The combination of VMI and MAR as well as MAR as a standalone approach enables effective reduction of artifacts from CIEDs. • Higher keV values of both VMI and VMI MAR at CIED leads should be applied with caution since diagnostic assessment can be hampered by a loss of soft tissue and vessel contrast. • Recommended keV values for CIED generators are between 140 and 200 keV and for leads around 100 keV.
    Type of Medium: Online Resource
    ISSN: 0938-7994 , 1432-1084
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 1472718-3
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  • 3
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 37, No. 15_suppl ( 2019-05-20), p. e14124-e14124
    Abstract: e14124 Background: Immune checkpoint inhibitor (ICI) has emerged as a novel systemic treatment for advanced cancers. As ICI modulates immune signaling pathways by targeting cytotoxic T-lymphocyte antigen-4 (CTLA-4), programmed death-1 (PD-1) or its ligands (PD-L1), a number of immune related adverse events (IRAE) have been reported. Whether IRAE can be a predictor for treatment response has remained controversial and we evaluated the association between IRAE and outcome. Methods: Retrospective chart and Computed Tomography (CT) review of patients with stage IV NSCLC treated with single agent Nivolumab or Pembrolizumab was performed. Any abnormalities in lab values, imaging finding or clinical signs to suggest pneumonitis, thyroiditis, hepatitis, nephritis, pancreatitis, colitis, pleural/pericardial effusion, arthritis or myositis between the start of the therapy and six months after the end of the therapy were recorded in a binary fashion. Abnormality in the setting of baseline abnormal values or due to clear cause other than IRAE has been excluded. Overall survival as well as best response based on RECIST 1.1 was also recorded. Results: 88 patients treated between January 2012 and March 2017 were identified. 62 patients, 42 patients and 50 patients demonstrated abnormalities in lab values, CT and clinical signs, respectively. When each subcategory was correlated with OS using ANOVA, thyroid function test abnormality (n = 15) and liver function test abnormality (n = 36) were associated with increased OS (p = 0.021, p = 0.038, respectively). Interestingly, elevated C-reactive protein was associated with decreased OS (p = 0.01). Initially, each score was given depending upon the number of abnormal categories (lab, imaging or clinical signs), ranging from score 0 (n = 7), 1 (n = 19), 2 (n = 33) and 3 (n = 17). Increased score was associated with increased OS (p = 0.03). For more detailed analysis, we came up with scoring system which sums up each score given for any abnormality in each subcategory. On Multivariate analysis, there was significant positive correlation between higher score and increased OS (p = 0.001). Conclusions: We have identified several IRAE parameters that were associated with increased OS. Furthermore, scoring system used in the study which encompassed clinical, radiologic and laboratory aspect, showed positive association with increased OS, indicating IRAE’s potential role as a biomarker.
    Type of Medium: Online Resource
    ISSN: 0732-183X , 1527-7755
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Clinical Oncology (ASCO)
    Publication Date: 2019
    detail.hit.zdb_id: 2005181-5
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  • 4
    In: European Journal of Radiology Open, Elsevier BV, Vol. 8 ( 2021), p. 100324-
    Type of Medium: Online Resource
    ISSN: 2352-0477
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 2810314-2
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  • 5
    In: Diagnostics, MDPI AG, Vol. 11, No. 6 ( 2021-06-01), p. 1016-
    Abstract: Background: in magnetic resonance imaging (MRI), automated detection of brain metastases with convolutional neural networks (CNN) represents an extraordinary challenge due to small lesions sometimes posing as brain vessels as well as other confounders. Literature reporting high false positive rates when using conventional contrast enhanced (CE) T1 sequences questions their usefulness in clinical routine. CE black blood (BB) sequences may overcome these limitations by suppressing contrast-enhanced structures, thus facilitating lesion detection. This study compared CNN performance in conventional CE T1 and BB sequences and tested for objective improvement of brain lesion detection. Methods: we included a subgroup of 127 consecutive patients, receiving both CE T1 and BB sequences, referred for MRI concerning metastatic spread to the brain. A pretrained CNN was retrained with a customized monolayer classifier using either T1 or BB scans of brain lesions. Results: CE T1 imaging-based training resulted in an internal validation accuracy of 85.5% vs. 92.3% in BB imaging (p 〈 0.01). In holdout validation analysis, T1 image-based prediction presented poor specificity and sensitivity with an AUC of 0.53 compared to 0.87 in BB-imaging-based prediction. Conclusions: detection of brain lesions with CNN, BB-MRI imaging represents a highly effective input type when compared to conventional CE T1-MRI imaging. Use of BB-MRI can overcome the current limitations for automated brain lesion detection and the objectively excellent performance of our CNN suggests routine usage of BB sequences for radiological analysis.
    Type of Medium: Online Resource
    ISSN: 2075-4418
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662336-5
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  • 6
    In: Clinical Neuroradiology, Springer Science and Business Media LLC, Vol. 31, No. 3 ( 2021-09), p. 815-826
    Abstract: To evaluate a novel flow-independent 3D isotropic REACT sequence compared with CE-MRA for the imaging of extracranial arteries in acute ischemic stroke (AIS). Methods This was a retrospective study of 35 patients who underwent a stroke protocol at 3 T including REACT (fixed scan time: 2:46 min) and CE-MRA of the extracranial arteries. Three radiologists evaluated scans regarding vessel delineation, signal, and contrast and assessed overall image noise and artifacts using 5-point scales (5: excellent delineation/no artifacts). Apparent signal- and contrast-to-noise ratios (aSNR/aCNR) were measured for the common carotid artery (CCA), internal carotid artery (ICA, C1 segment), and vertebral artery (V2 segment). Two radiologists graded the degree of proximal ICA stenosis. Results Compared to REACT, CE-MRA showed better delineation for the CCA and ICA (C1 and C2 segments) (median 5, range 2–5 vs. 4, range 3–5; P   〈  0.05). For the ICA (C1 and C2 segments), REACT provided a higher signal (5, range 3–5; P   〈  0.05/4.5, range 3–5; P   〉  0.05 vs. 4, range 2–5) and contrast (5, range 3–5 vs. 4, range 2–5; P   〉  0.05) than CE-MRA. The remaining segments of the blood-supplying vessels showed equal medians. There was no significant difference regarding artifacts, whereas REACT provided significantly lower image noise (4, range 3–5 vs. 4 range 2–5; P   〈  0.05) with a higher aSNR ( P   〈  0.05) and aCNR ( P   〈  0.05) for all vessels combined. For clinically relevant (≥50%) ICA stenosis, REACT achieved a detection sensitivity of 93.75% and a specificity of 100%. Conclusion Given its fast acquisition, comparable image quality to CE-MRA and high sensitivity and specificity for the detection of ICA stenosis, REACT was proven to be a clinically applicable method to assess extracranial arteries in AIS.
    Type of Medium: Online Resource
    ISSN: 1869-1439 , 1869-1447
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2232347-8
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  • 7
    In: Clinical Neuroradiology, Springer Science and Business Media LLC, Vol. 31, No. 2 ( 2021-06), p. 357-366
    Type of Medium: Online Resource
    ISSN: 1869-1439 , 1869-1447
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2232347-8
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  • 8
    In: Acta Radiologica, SAGE Publications, Vol. 61, No. 8 ( 2020-08), p. 1143-1152
    Abstract: In abdominal imaging, contrast-enhanced computed tomography (CT) examinations are most commonly applied; however, unenhanced examinations are still needed for several clinical questions but require additional scanning and radiation exposure. Purpose To evaluate accuracy of virtual non-contrast (VNC) from arterial and venous phase spectral-detector CT (SDCT) scans compared to true-unenhanced (TNC) images for the evaluation of liver parenchyma and vessels. Material and Methods A total of 25 patients undergoing triphasic SDCT examinations were included. VNC was reconstructed from arterial and venous phases and compared to TNC images. Quantitative image analysis was performed by region of interest (ROI)-based assessment of mean and SD of attenuation (HU) in each liver segment, spleen, portal vein, common hepatic artery, and abdominal aorta. Subjectively, iodine subtraction and diagnostic assessment were rated on 5-point Likert scales. Results Attenuation and image noise measured in the liver from VNC were not significantly different from TNC (TNC: 54.6 ± 10.8 HU, VNC arterial phase: 55.7 ± 10.8 HU; VNC venous phase: 58.3 ± 10.0 HU; P  〉  0.05). VNC also showed accurate results regarding attenuation and image noise for spleen, portal vein, and abdominal aorta. Only iodine subtraction in the common hepatic artery in the arterial phase was insufficient which was confirmed by the subjective reading. Apart from that, subjective reading showed accurate iodine subtraction and comparable diagnostic assessment. Conclusion VNC from the arterial and venous phases were very similar to TNC yielding mostly negligible differences in attenuation, image noise, and diagnostic utility. Inadequate iodine subtraction occurred in hepatic arteries in the arterial phase.
    Type of Medium: Online Resource
    ISSN: 0284-1851 , 1600-0455
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2024579-8
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  • 9
    In: Journal of Computer Assisted Tomography, Ovid Technologies (Wolters Kluwer Health), Vol. 46, No. 5 ( 2022-9), p. 735-741
    Abstract: Preimplantation cardiac computed tomography (CT) for assessment of the left atrial appendage (LAA) enables correct sizing of the device and the detection of contraindications, such as thrombi. In the arterial phase, distinction between false filling defects and true thrombi can be hampered by insufficient contrast medium distribution. A delayed scan can be used to further differentiate both conditions, but contrast in these acquisitions is relatively lower. In this study, we investigated whether virtual monoenergetic images (VMI) from dual-energy spectral detector CT (SDCT) can be used to enhance contrast and visualization in the delayed phase. Materials and Methods Forty-nine patients receiving SDCT imaging of the LAA were retrospectively enrolled. The imaging protocol comprised dual-phase acquisitions with single-bolus contrast injection. Conventional images (CI) from both phases and 40-keV VMI from the delayed phase were reconstructed. Attenuation, signal-, and contrast-to-noise ratios (SNR/CNR) were calculated by placing regions-of-interest in the LAA, left atrium, and muscular portion of interventricular septum. Two radiologists subjectively evaluated conspicuity and homogeneity of contrast distribution within the LAA. Results Contrast of the LAA decreased significantly in the delayed phase but was significantly improved by VMI, showing comparable attenuation, SNR, and CNR to CI from the arterial phase (attenuation/SNR/CNR, CI arterial phase: 266.0 ± 117.0 HU/14.2 ± 7.2/6.6 ± 3.9; CI-delayed phase: 107.6 ± 35.0 HU/5.9 ± 3.0/1.0 ± 1.0; VMI delayed phase: 260.3 ± 108.6 HU/18.2 ± 10.6/4.8 ± 3.4). The subjective reading confirmed the objective findings showing improved conspicuity and homogeneity in the delayed phase. Conclusions The investigated single-bolus dual-phase acquisition protocol provided improved visualization of the LAA. Homogeneity of contrast media was higher in the delayed phase, while VMI maintained high contrast.
    Type of Medium: Online Resource
    ISSN: 1532-3145 , 0363-8715
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 2039772-0
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  • 10
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-12-09)
    Abstract: Dual-energy CT allows for the reconstruction of virtual non-contrast (VNC) images. VNC images have the potential to replace true non-contrast scans in various clinical applications. This study investigated the quantitative accuracy of VNC attenuation images considering different parameters for acquisition and reconstruction. An abdomen phantom with 7 different tissue types (different combinations of 3 base materials and 5 iodine concentrations) was scanned using a spectral detector CT (SDCT). Different phantom sizes (S, M, L), volume computed tomography dose indices (CTDIvol 10, 15, 20 mGy), kernel settings (soft, standard, sharp), and denoising levels (low, medium, high) were tested. Conventional and VNC images were reconstructed and analyzed based on regions of interest (ROI). Mean and standard deviation were recorded and differences in attenuation between corresponding base materials and VNC was calculated (VNCerror). Statistic analysis included ANOVA, Wilcoxon test and multivariate regression analysis. Overall, the VNC error was − 1.4 ± 6.1 HU. While radiation dose, kernel setting, and denoising level did not influence VNC error significantly, phantom size, iodine content and base material had a significant effect (e.g. S vs. M: − 1.2 ± 4.9 HU vs. − 2.1 ± 6.0 HU; 0.0 mg/ml vs. 5.0 mg/ml: − 4.0 ± 3.5 HU vs. 5.1 ± 5.0 HU and 35-HU-base vs. 54-HU-base: − 3.5 ± 4.4 HU vs. 0.7 ± 6.5; all p  ≤ 0.05). The overall accuracy of VNC images from SDCT is high and independent from dose, kernel, and denoising settings; however, shows a dependency on patient size, base material, and iodine content; particularly the latter results in small, yet, noticeable differences in VNC attenuation.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2615211-3
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