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Endovascular aneurysm repair EVAR has been gaining popularity over open repair of abdominal aortic aneurysms AAAs in the recent years. This paper describes a distortion correction approach to be applied during the EVAR cases. In a novel workflow, models meshes of the aorta and its branching arteries generated from preoperatively acquired computed tomography CT scans are overlayed with interventionally acquired fluoroscopic images. The overlay provides an arterial roadmap for the operator, with landmarks LMs marking the ostia, which are critical for stent placement. As several endovascular devices, such as angiographic catheters, are inserted, the anatomy may be distorted. The distortion reduces the accuracy of the overlay. To overcome the mismatch, the aortic and the iliac meshes are adapted to a device seen in uncontrasted intraoperative fluoroscopic images using the skeletonbased as-rigid-as-possible ARAP method. The deformation was evaluated by comparing the distance between an ostium and the corresponding LM prior to and after the deformation. The central positions of the ostia were marked in digital subtraction angiography DSA images as ground truth. The mean Euclidean distance in the image plane was reduced from 19.81±17.14mm to 4.56±2.81 mm.

Background and Purpose— Initial reports indicate that transcranial harmonic imaging after ultrasound contrast agent bolus injection (BHI) can detect cerebral perfusion deficits in acute ischemic stroke. We evaluated parametric images of the bolus washout kinetics. Methods— Twenty-three patients with acute internal carotid artery infarction were investigated with perfusion harmonic imaging after SonoVue bolus injection ≤40 hour after the onset of symptoms. The findings were compared with those of cranial computed tomography (CCT) and clinical course 4 months after stroke. Results— Images of pixel-wise peak intensity (PPI) and time to peak intensity could be calculated for all patients. Spearman rank correlations of r =0.772 ( P r =0.572 ( P =0.008) between area of PPI signal decrease and area of infarction in the follow-up CCT as well as outcome after 4 months were obtained, respectively. Conclusions— In the early phase of acute ischemic stroke, BHI after SonoVue bolus injection is a useful ultrasound tool for analyzing cerebral perfusion deficits at the patient’s bedside. BHI data correlate with the definite area of infarction and outcome after 4 months.

To retrospectively assess the use of a combination of cancellous bone reconstructions (CBR) and multiplanar reconstructions (MPRs) for the detection of bone metastases at thoracoabdominal computed tomography (CT) compared with the use of MPRs alone.The study was approved by the local institutional review board. Included were 156 consecutive patients with confirmed cancer who underwent a whole-body positron emission tomography (PET)/CT examination for clinical purposes (93 male and 63 female patients; mean age ± standard deviation, 59.8 years ± 14.9; range, 11-85 years). Only the CT images were processed with the CBR algorithm, which segments the bones and removes the cortical layer from the images. The PET images served as part of the reference standard. Images from 15 patients were used as a training set. Four radiologists independently evaluated images of half of the remaining 141 patients by using CBRs and MPRs together, and the other half by using MPRs only. Radiologists were blinded to patient names, and patient order was randomized. Results for detection rates and reporting time were recorded and compared with a standard of reference for each patient that was created by one senior radiologist and one nuclear medicine specialist by using all available CT and PET data, CBRs, and follow-up examinations. General estimation equations were used for statistical analysis.There were 349 lesions found in 103 patients, with 203 classified as malignant. Each patient was assessed by two readers per method, leading to a total of 698 lesions. The detection rate for all bone lesions was 35% (247 of 698) for MPRs and 74% (520 of 698) when CBRs and MPRs were used together, which was significantly higher (P.001). The average reading time decreased from 85 to 43 seconds (P.001) when both reconstructions were used.Advanced visualization of cancellous bone significantly increased the detection of bone metastases and reduced the time for interpretation.

Numerical simulations have shown a significant influence of group-velocity dispersion (GVD) of the highly nonlinear fiber on the transfer characteristics of a nonlinear amplifying loop mirror (NALM). The effect is especially strong for the anomalous dispersion regime where an interaction of GVD and self-phase modulation (SPM) leads to formation of high-order solitons. The irregularities of the resulting NALM transfer functions can be used for phase-preserving amplitude regeneration of several, irregular-spaced amplitude states for multi-level modulation formats. The regeneration performance was estimated for a 16QAM signal with three amplitude states where a reduction of amplitude noise without significant signal phase distortions has been observed.

Performability control of IT systems still lacks theoretically well-founded approaches that fit well to enterprise system management solutions. We propose a methodology for designing compact qualitative, state-based predictive performability control that use instrumentation provided by typical system monitoring frameworks. We identify the main systemic insufficiencies of current monitoring tools that hinder designing trustworthy fine-granular controls.

Supervisory control is the main means to assure a high level performance and availability of large IT infrastructures. Applied control theory is used in physical and virtualization based clustering, autonomic-, self-healing and cloud computing, but similar problems arise in any distributed environment.

Fast visualisation of cerebral microcirculation supports diagnosis of acute stroke. However, the commonly used CT/MRI-based methods are time consuming, costly and not applicable to every patient. The bolus perfusion harmonic imaging (BHI) method is an ultrasound imaging technique which makes use of the fact, that ultrasound contrast agents unlike biological tissues resonate at harmonic frequencies. Exploiting this effect, the contrast between perfused and non-perfused areas can be improved. Thus, BHI overcomes the low signal-to-noise ratio of transcranial ultrasound and the high impedance of the skull. By analysing image sequences, visualising the qualitative characteristics of an US contrast agent bolus injection becomes possible. The analysis consists of calculating four perfusion-related parameters, Local Peak Intensity, Time To Peak, Area Under Curve, and Average Rising, from the time/intensity curve and providing them as colour-coded images. For calculating these parameters the fundamental assumption is that image intensity corresponds to contrast agent concentration which in turn shows the perfusion of the corresponding brain region. In a clinical study on patients suffering from acute ischemic stroke it is shown that some of the parameters correlate significantly to the infarction area. Thus, BHI becomes a less time-consuming and inexpensive bedside method for diagnosis of cerebral perfusion deficits.

Moving objects in image sequences acquired by a static camera can be detected by analyzing the grey-level difference between successive frames. Direct motion detection, however, will also detect fast variations of scene illumination. This paper describes a method for motion detection that is considerably less sensitive to time-varying illumination. It is based on combining a motion detection algorithm with an homomorphic filter which effectively suppresses variable scene illumination. To this end, the acquired image sequence is modelled as being generated by an illumination and a reflectance component that are approximately separated by the filter. Detection of changes in the reflectance component is directly related to scene changes, i.e., object motion. Real video data are used to illustrate the system's performance.

Die zuverlassige und schnelle Messung der zerebralen Mikrozirkulation ist entscheidend fur die Diagnose und Behandlung akuter zerebrovaskularer Erkrankungen. Die Perfusionsmessung mittels intrakranieller Ultraschallbildgebung bietet hierfur eine zeitsparende und mobil einsetzbare Alternative zu den aufwandigen tomographischen Verfahren. Der kombinierte Einsatz von Harmonic-Imaging Bildgebung und geeigneten Signalverstarkern erlaubt die Bestimmung der lokalen Hirnperfusion aus der Kontrastmittelkinetik uber ein Perfusionsmodell. Die resultierenden Flusbilder ermoglichen die schnelle Lokalisierung minderdurchbluteter Bereiche bei minimaler physischer und psychischer Patientenbelastung. Die diagnostische Relevanz der Flusbilder konnte in einer Probandenstudie nachgewiesen werden.

Die Darstellung und quantitative Auswertung der Hirnperfusion liefert wichtige diagnostische Hinweise. Mit der Computer-bzw. Magnet-Resonanz Tomographie stehen hierfur derzeit kosten- und zeitintensive Verfahren zur Verfugung. Demgegenuber stellt die Echo- densitometrie eine alternative, mobil einsetzbare Methode dar. Das dabei verwendete Ultraschallkontrastmittel besteht aus gasgefullten Mikroblaschen und bringt daher nur eine minimale Patientenbelastung mit sich. Verschiedene Faktoren schranken allerdings die Bildqualitat drastisch ein. Dieser Beitrag stellt eine neuartige Methode zur automatischen Quantifizierung der zerebralen Mikrozirkulation vor. Hierzu werden Harmonie Imaging Bildsequenzen mit stetig steigendem Aufnahmeintervall aufgenommen. Dadurch kann eine Sattigungskurve des Kontrastmittels im Blut ermittelt werden, aus deren Steigung sich die Flusgeschwindigkeit ergibt. Ein normiertes Mas fur die Hirnperfusion ist hieraus ableitbar. Weiterhin wird eine Verbesserung des Verfahrens vorgeschlagen, die auf den Musterspektrum der tiefpasgefilterten Bildsequenz basiert.

Objectives: To evaluate the diagnostic usefulness of synthetic T2-weighted images of the lumbar spine derived from ten-fold undersampled k-space data using GRAPPATINI, a combination of a model-based approach for rapid T2 and M0 quantification (MARTINI) extended by generalized autocalibrating partial parallel acquistion (GRAPPA). Materials and methods: Overall, 58 individuals (26 female, mean age 23.3 +/- 8.1 years) were examined at 3 Tesla with sagittal and axial T2w turbo spin echo (TSE) sequences compared to synthetic T2_weighted contrasts derived at identical effective echo times and spatial resolutions. Two blinded readers graded disk degeneration and evaluated the lumbar intervertebral disks for present herniation or annular tear. One reader reassessed all studies after four weeks. Weighted kappa statistics were calculated to assess inter-rater and intra-rater agreement. Also, all studies were segmented manually by one reader to compute contrast ratios (CR) and contrast-tonoise ratios (CNR) of the nucleus pulposus and the annulus fibrosus. Results: Overall, the CRT2w was 4.45 +/- 1.80 and CRT2synth was 4.71 +/- 2.14. Both correlated (rsp = 0.768;p < 0.001) and differed (0.26 +/- 1.38;p = 0.002) significantly. The CNRT2w was 1.73 +/- 0.52 and CNRT2synth was 1.63 +/- 0.50. Both correlated (rsp = 0.875;p < 0.001) and differed (-0.10 +/- 0.25;p < 0.001) significantly. The interrater agreement was substantial to almost perfect (Kappa = 0.808-0.925) with the intra-rater agreement also substantial to almost perfect (Kappa = 0.862-0.963). The area under the curve of the receiver operating characteristics assessing disk herniation or annular tear ranged from 0.787 to 0.892. Conclusions: This study concludes that synthetic images derived by GRAPPATINI can be used for clinical routine assessment with inter-rater and intra-rater agreements comparable to conventional T2w TSE.

Non-zero fiber dispersion in a Sagnac interferometer can significantly improve multilevel phase-preserving amplitude regeneration. Soliton effects can be used to create irregularly spaced plateaus for high-power states of complex modulation formats.