Influence of motion correction on the visual analysis of cardiac magnetic resonance stress perfusion imaging

Objective

Image post-processing corrects for cardiac and respiratory motion (MoCo) during cardiovascular magnetic resonance (CMR) stress perfusion. The study analyzed its influence on visual image evaluation.

Materials and methods

Sixty-two patients with (suspected) coronary artery disease underwent a standard CMR stress perfusion exam during free-breathing. Image post-processing was performed without (non-MoCo) and with MoCo (image intensity normalization; motion extraction with iterative non-rigid registration; motion warping with the combined displacement field). Images were evaluated regarding the perfusion pattern (perfusion deficit, dark rim artifact, uncertain signal loss, and normal perfusion), the general image quality (non-diagnostic, imperfect, good, and excellent), and the reader’s subjective confidence to assess the images (not confident, confident, very confident).

Results

Fifty-three (non-MoCo) and 52 (MoCo) myocardial segments were rated as ‘perfusion deficit’, 113 vs. 109 as ‘dark rim artifacts’, 9 vs. 7 as ‘uncertain signal loss’, and 817 vs. 824 as ‘normal’. Agreement between non-MoCo and MoCo was high with no diagnostic difference per-patient. The image quality of MoCo was rated more often as ‘good’ or ‘excellent’ (92 vs. 63%), and the diagnostic confidence more often as “very confident” (71 vs. 45%) compared to non-MoCo.

Conclusions

The comparison of perfusion images acquired during free-breathing and post-processed with and without motion correction demonstrated that both methods led to a consistent evaluation of the perfusion pattern, while the image quality and the reader’s subjective confidence to assess the images were rated more favorably for MoCo.

     

Aqueous-Base-Developable Benzocyclobutene (BCB)-Based Material Curable in Air

A positive-tone and aqueous-base-developable benzocyclobutene (BCB)-based dielectric material curable in air is described in this paper. The prepolymer is made from divinylsiloxane bisbenzocyclobutene (DVS-bisBCB) and BCB-acrylic acid. The formulation contains antioxidants that allow the prepolymer to cure in air and a diazonaphthaquinone to make it photosensitive. Patterned films have high resolution, and via openings are scum-free without a descum operation. Whether cured in nitrogen or in air, the prepolymer produces a film with optical, electrical, thermal, and mechanical properties desirable for many microelectronic applications, such as packaging applications and as a planarization or insulation layer in display applications     

Impact of picocells on the capacity and energy efficiency of mobile networks

The deployment of small cells in mobile networks has aroused a large interest in the last few years. This paper investigates the impact of picocell deployment on the performance and power consumption of mobile networks. Since different network upgrades introduce different performance gains, comparing different configurations exclusively on their overall power consumption can be rather biased. For this reason, a new key performance indicator, termed “energy efficiency”, is introduced and used throughout this study, bringing together network performance and its overall power consumption. In the first section of the study, a theoretical analysis for the Erlang-like capacity of a network, considering a uniform topology and traffic, is performed, using queuing theory analysis, namely processor-sharing queues. Results show that in all cases the deployment of picocells improve the performance of the network, however the energy efficiency is noted to be dependent on the deployment scenario considered. In the second part of the study, a more realistic scenario with non-uniform topology and traffic is considered, which is carried out through a large-scale system level simulator. Results show that by deploying picocells in areas experiencing high levels of traffic, the energy efficiency of the network can be considerably improved.     

Design of a Simulation Package for Automated Guided Vehicle Systems

The lack of analytical techniques in designing optimal network configurations and control policies in Automated Guided Vehicle Systems (AGVS) leaves simulation as the designer's primary tool. ASP is a general purpose AGVS Simulation Package developed in SIMAN and FORTRAN. This interactive package is designed to relieve the user of programming the simulation model and allow the user to input different design configurations quickly. The package consists of an interactive user interface, a model file which contains the generic portion of the system model and an experiment file which contains user defined parameters which are problem specific. The user enters the network topology, vehicle operating characteristics and selects system and simulation control policies. Waiting time at each intersection and station and total system time are the general output of the package and may be further analyzed using the SIMAN Output Processor.     

Lack of Pervasiveness of the Underconfidence-With-Practice Effect: Boundary Conditions and an Explanation Via Anchoring.

The authors investigated whether underconfidence in judgments of learning (JOLs) is pervasive across multiple study-test trials as suggested by A. Koriat, L. Sheffer, and H. Ma'ayan (2002) or whether underconfidence with practice (UWP) might be a kind of anchoring-and-adjustment effect, such that the occurrence or nonoccurrence of the UWP effect depends on whether recall is above a psychological anchor. Participants studied normatively difficult items or normatively easy items and made immediate JOLs or delayed JOLs. The UWP effect occurred for easy items, but for difficult items an overconfidence-with-practice (OWP) effect occurred for delayed JOLs and no bias occurred for immediate JOLs. The systematic occurrence of all 3 outcomes establishes boundary conditions for the UWP effect and confirms the hypothesis that underconfidence (or the lack thereof) may arise at least in part from an anchoring-and-adjustment mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Expression of the genes encoding myelin basic protein and proteolipid protein in human malignant gliomas

Pathological differentiation of oligodendroglioma and mixed oligoastrocytoma from astrocytoma is difficult, relying on morphological characteristics due to the lack of reliable immunohistochemical stains. Oligodendrocytes, the presumed cell of origin of oligodendrogliomas, highly express the genes encoding myelin basic protein (MBP) and proteolipid protein (PLP). We analyzed the expression of these genes to determine whether they might be useful molecular markers of oligodendrocytic tumors. MBP and PLP were highly expressed in all oligodendrogliomas and minimally expressed in glioblastomas multiforme. MBP was highly expressed in mixed oligoastrocytomas, whereas PLP expression was minimal. The association between tumor classification and expression of the MBP and PLP genes was statistically significant. Expression of these genes may serve as a useful molecular marker for some subtypes of human gliomas.     

Radiation dose and image quality in spiral computed tomography: multicentre evaluation at six institutions

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