Impact of a 4th generation iterative reconstruction technique on image quality in low-dose computed tomography of the chest in immunocompromised patients

PURPOSE To determine the image quality of an iterative reconstruction (IR) technique in low-dose MDCT (LDCT) of the chest of immunocompromised patients in an intraindividual comparison to filtered back projection (FBP) and to evaluate the dose reduction capability. MATERIALS AND METHODS 30 chest LDCT scans were performed in immunocompromised patients (Brilliance iCT; 20-40 mAs; mean CTDIvol: 1.7 mGy). The raw data were reconstructed using FBP and the IR technique (iDose4™, Philips, Best, The Netherlands) set to seven iteration levels. 30 routine-dose MDCT (RDCT) reconstructed with FBP served as controls (mean exposure: 116 mAs; mean CDTIvol: 7.6 mGy). Three blinded radiologists scored subjective image quality and lesion conspicuity. Quantitative parameters including CT attenuation and objective image noise (OIN) were determined. RESULTS In LDCT high iDose4™ levels lead to a significant decrease in OIN (FBP vs. iDose7: subscapular muscle 139.4 vs. 40.6 HU). The high iDose4™ levels provided significant improvements in image quality and artifact and noise reduction compared to LDCT FBP images. The conspicuity of subtle lesions was limited in LDCT FBP images. It significantly improved with high iDose4™ levels (> iDose4). LDCT with iDose4™ level 6 was determined to be of equivalent image quality as RDCT with FBP. CONCLUSION iDose4™ substantially improves image quality and lesion conspicuity and reduces noise in low-dose chest CT. Compared to RDCT, high iDose4™ levels provide equivalent image quality in LDCT, hence suggesting a potential dose reduction of almost 80%.

Image-based vs. mesh-based statistical appearance models of the human femur: Implications for finite element simulations.

Statistical appearance models have recently been introduced in bone mechanics to investigate bone geometry and mechanical properties in population studies. The establishment of accurate anatomical correspondences is a critical aspect for the construction of reliable models. Depending on the representation of a bone as an image or a mesh, correspondences are detected using image registration or mesh morphing. The objective of this study was to compare image-based and mesh-based statistical appearance models of the femur for finite element (FE) simulations. To this aim, (i) we compared correspondence detection methods on bone surface and in bone volume; (ii) we created an image-based and a mesh-based statistical appearance models from 130 images, which we validated using compactness, representation and generalization, and we analyzed the FE results on 50 recreated bones vs. original bones; (iii) we created 1000 new instances, and we compared the quality of the FE meshes. Results showed that the image-based approach was more accurate in volume correspondence detection and quality of FE meshes, whereas the mesh-based approach was more accurate for surface correspondence detection and model compactness. Based on our results, we recommend the use of image-based statistical appearance models for FE simulations of the femur.

Image registration for triggered and non-triggered DTI of the human kidney: Reduced variability of diffusion parameter estimation

BACKGROUND: To investigate if non-rigid image-registration reduces motion artifacts in triggered and non-triggered diffusion tensor imaging (DTI) of native kidneys. A secondary aim was to determine, if improvements through registration allow for omitting respiratory-triggering. METHODS: Twenty volunteers underwent coronal DTI of the kidneys with nine b-values (10-700 s/mm2 ) at 3 Tesla. Image-registration was performed using a multimodal nonrigid registration algorithm. Data processing yielded the apparent diffusion coefficient (ADC), the contribution of perfusion (FP ), and the fractional anisotropy (FA). For comparison of the data stability, the root mean square error (RMSE) of the fitting and the standard deviations within the regions of interest (SDROI ) were evaluated. RESULTS: RMSEs decreased significantly after registration for triggered and also for non-triggered scans (P < 0.05). SDROI for ADC, FA, and FP were significantly lower after registration in both medulla and cortex of triggered scans (P < 0.01). Similarly the SDROI of FA and FP decreased significantly in non-triggered scans after registration (P < 0.05). RMSEs were significantly lower in triggered than in non-triggered scans, both with and without registration (P < 0.05). CONCLUSION: Respiratory motion correction by registration of individual echo-planar images leads to clearly reduced signal variations in renal DTI for both triggered and particularly non-triggered scans. Secondarily, the results suggest that respiratory-triggering still seems advantageous.J. Magn. Reson. Imaging 2014. (c) 2014 Wiley Periodicals, Inc.

Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise

OBJECTIVE The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT) by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP) and an iterative reconstruction (IR) algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany) was investigated. MATERIALS AND METHODS 136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP), SOMATOM Definition Flash (IR), and SOMATOM Definition Edge (ICD and IR). Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product. RESULTS Dose-length product (DLP) with FBP for the average chest CT was 308 mGy*cm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGy*cm ± 68.8 (P = 0.0001). Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGy*cm ± 54.5 (P = 0.033). The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR) was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048). Overall contrast-to-noise ratio (CNR) improved with declining DLP. CONCLUSION The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations.

Diffusion tensor imaging of the human kidney: Does image registration permit scanning without respiratory triggering?

PURPOSE To investigate if image registration of diffusion tensor imaging (DTI) allows omitting respiratory triggering for both transplanted and native kidneys MATERIALS AND METHODS: Nine kidney transplant recipients and eight healthy volunteers underwent renal DTI on a 3T scanner with and without respiratory triggering. DTI images were registered using a multimodal nonrigid registration algorithm. Apparent diffusion coefficient (ADC), the contribution of perfusion (FP ), and the fractional anisotropy (FA) were determined. Relative root mean square errors (RMSE) of the fitting and the standard deviations of the derived parameters within the regions of interest (SDROI ) were evaluated as quality criteria. RESULTS Registration significantly reduced RMSE in all DTI-derived parameters of triggered and nontriggered measurements in cortex and medulla of both transplanted and native kidneys (P < 0.05 for all). In addition, SDROI values were lower with registration for all 16 parameters in transplanted kidneys (14 of 16 SDROI values were significantly reduced, P < 0.04) and for 15 of 16 parameters in native kidneys (9 of 16 SDROI values were significantly reduced, P < 0.05). Comparing triggered versus nontriggered DTI in transplanted kidneys revealed no significant difference for RMSE (P > 0.14) and for SDROI (P > 0.13) of all parameters. In contrast, in native kidneys relative RMSE from triggered scans were significantly lower than those from nontriggered scans (P < 0.02), while SDROI was slightly higher in triggered compared to nontriggered measurements in 15 out of 16 comparisons (significantly for two, P < 0.05). CONCLUSION Registration improves the quality of DTI in native and transplanted kidneys. Diffusion parameters in renal allografts can be measured without respiratory triggering. In native kidneys, respiratory triggering appears advantageous. J. Magn. Reson. Imaging 2016.

Step by step: correcting our mental image of the mušlālu

The mušlālu, which is usually understood to be a step- or ramped gate, has so far rarely been discussed in much detail, even though the texts mentioning it have been known for a long time. This is no doubt because the evidence on which to base both philological and archaeological investigations appears sparse and scattered. Up to now, scholars have tended to focus on specific mušlālu-structures. Consequently, there are as many discussions as there are mušlālu-structures. This article attempts to get a sense of the broader picture by bringing together the philological and archaeological data hitherto available with the aim of discussing the mušlālu as term and structure, clarifying the semantics and reassessing the architectural identifications. We hope to demonstrate that it is actually possible to take the evidence one step further and correct the mušlālu image that prevails.

Na 1 Nachlass Max Horkheimer, 711 - Zu "Image de la France. Un sondage de l'opinion publique allemande" und "Enquête sur l'écoute et les conditions d'efficacité des émissions en langue allemande de la Radiodiffusion Francais à destination de l'Allemangne" sowie "The Effectiveness of Candid versus Evasive German-Language Broadcasts of the Voice of America. Final Report" (p. IX 185.3-22 - IX 186)

3. "Plan d'ensemble d'une enquête sur les attitudes generales de la population allemande a l'egard de la France et leurs consequences en ce qui concerne l'orientation des emissions en langue allemande de la radiodiffusion francaise", 18.05.1953. Typoskript, 7 Blatt; 4. "Note" Über Methode, Forschungsrichtung und Reichweite der Ergebnisse der Untersuchung; 18.05.1953; Typoskript, 7 Blatt; 5. "Note" Über Geschichte und Tätigkeit des Instituts für Sozialforschung; 18.05.1953; Typoskript, 5 Blatt; 6. Memorandum des Instituts zu Verfahren und ergebnissen der Untersuchung; 1954 [?]; Typoskript, 2 Blatt; 7.-17. Décamps, Jacques: Memoranden; 7. Memorandum, 12.09.1953; Typoskript, 1 Blatt; 8. "Memorandum re: Besprechung in Bad Godesberg in Bezug auf die französische Studie, am 04.September 1953", 10.09.1953. Typoskript, 1 Blatt; 9. "Memorandum re: Vorhaben des 'Centre d'Etudes Sociologiques, Paris', eine deutsch-französische Arbeitsgemeinschft für die Durchführung von Gemeindestudien zu gründen", 15.06.1953. Typoskript, 1 Blatt; 10. "Memorandum über den Besuch von M. Jean L. Pelosse, Centre d'Etudes sociologiques Paris", 12.06.1953. Typoskript, 3 Blatt; 11. "Bericht über die 'Journées d'Etudes eurropéennes sur la Population' Paris, 21., 22. und 23. Mai 1953", 01.06.1953; 12. "Bericht über den Stand der Verhandlungen mit dem Französischen Auswärtigen Amt und dem französischem Rundfunk. Besprechungen in Paris am 27. und 28. Mai 1953", 01.06.1953. Typoskript, 2 Blatt; 13. Angaben für Max Horkheimer zur Übergabe von Memoranden, Projektbeschreibungen und Briefentwürfen, Mai 1953; Typoskript, 1 Blatt; 14. "Bericht über das 'Institut National d'Etudes Démographiques'", 07.05.1953. Typoskript, 4 Blatt; 15. "Memorandum re: Methode der Gruppendiskussion", 04.05.1953. Typoskript, 1 Blatt; 16. "Besprechung im 'Institut francaise d'Opinion Publique, Paris' und bei der hohen Behörde Luxemburg" 30.04.1953; 17. "Besprechung im Auswärtigen Amt und bei dem französischen Rundfunk", 29.04.1953. Typoskript, 6 Blatt; 18. Horkheimer, Max: 1 Brief an den französischen Botschafter in der Bundesrepublik Deutschland, ohen Ort, ohne Datum; Typoskript, 1 Blatt; 19. Radiodiffusion-Télévision Francaise, le Directeur: 1 Briefabschrift an Jacques Décamps, Paris, 09.03.1954; 1 Blatt; 20. Plessner, Helmuth: 1 Brief an den französischen Außenminister, ohne Ort, 18.05.1953; 1 Blatt; 21. Plessner, Helmuth: 1 Brief an Radiodiffusion Francaise, ohne Ort, 18.05.1953; 1 Blatt; 22. Plessner, Helmuth: 1 Brief an den Ministerialrat der Sektion "Agences et Radio" im französischem Außenministerium, ohne Ort, 18.05.1953; 1 Blatt; "The Effectiveness of Candid versus Evasive German-Language Broadcasts of the Voice of America. Final Report", 1953. Typoskript, gebunden, 432 Blatt;

Potential of RapidEye image data for sediment monitoring of the German tidal flats

The Wadden Sea is located in the southeastern part of the North Sea forming an extended intertidal area along the Dutch, German and Danish coast. It is a highly dynamic and largely natural ecosystem influenced by climatic changes and anthropogenic use of the North Sea. Changes in the environment of the Wadden Sea, natural or anthropogenic origin, cannot be monitored by the standard measurement methods alone, because large-area surveys of the intertidal flats are often difficult due to tides, tidal channels and unstable underground. For this reason, remote sensing offers effective monitoring tools. In this study a multi-sensor concept for classification of intertidal areas in the Wadden Sea has been developed. Basis for this method is a combined analysis of RapidEye (RE) and TerraSAR-X (TSX) satellite data coupled with ancillary vector data about the distribution of vegetation, mussel beds and sediments. The classification of the vegetation and mussel beds is based on a decision tree and a set of hierarchically structured algorithms which use object and texture features. The sediments are classified by an algorithm which uses thresholds and a majority filter. Further improvements focus on radiometric enhancement and atmospheric correction. First results show that we are able to identify vegetation and mussel beds with the use of multi-sensor remote sensing. The classification of the sediments in the tidal flats is a challenge compared to vegetation and mussel beds. The results demonstrate that the sediments cannot be classified with high accuracy by their spectral properties alone due to their similarity which is predominately caused by their water content.