Sectra (Sweden)

Abstract Introduction Total wrist arthroplasty (TWA) is a motion-preserving treatment option for wrist arthritis. High-precision measurement methods for implant migration such as computed tomography motion-analysis (CTMA) can potentially detect poor implant fixation. The aim of this pilot study was to assess CTMA as a complementary method to diagnose aseptic loosening of TWA. Materials and Methods Three patients with a TWA and wrist pain during activity underwent induced displacement CT (CTMA) with alternated provocations as a complement to plain radiographs. Results Two of the three patients had displacement of the carpal component on CTMA. The radial component was stable in all cases. The tool was adapted to clinical routine use. Conclusions CT motion-analysis could be a valuable adjunct to plain radiographs in assessing component loosening in TWA.

Abstract Visual representations based on circular shapes are frequently used in visualization applications. One example are circos plots within bioinformatics, which bend graphs into a wheel of information with connective lines running through the center like spokes. The results are aesthetically appealing and impressive visualizations that fit long data sequences into a small quadratic space. However, the authors' experiences are that when asked, a visualization researcher would generally advise against making visualizations with radial layouts. Upon reviewing the literature we found that there is evidence that circular layouts are preferable in some cases, but we found no clear evidence for what layout is preferable for matrices and connective data in particular, which both are common data types in circos plots. In this work, we thus performed a user study to compare circular and linear layouts. The tasks are inspired by genomics data, but our results generalize to many other application areas, involving comparison and connective data. To build the prototype we utilized Gosling, a grammar for visualizing genomics data. We contribute empirical evidence on the suitedness of linear versus circular layouts, adding to the specific and general knowledge concerning perception of circular graphs. In addition, we contribute a case study evaluation of the grammar Gosling as a rapid prototyping language, confirming its utility and providing guidance on suitable areas for future development.

Chapter Contents: 10.1 Background on GPU computing 10.1.1 GPU architecture 10.1.2 Performance considerations 10.1.3 CPU – GPU heterogeneous platforms 10.2 Packet processing on the GPU 10.2.1 Related work 10.2.2 Throughput vs latency dilemma 10.2.3 An adaptive approach 10.2.4 Offline building of the batch-size table 10.2.5 Runtime batch size selection 10.2.6 Switching between batch sizes 10.3 Persistent kernel 10.3.1 Persistent kernel challenges 10.3.2 Proposed software architecture 10.4 Case study 10.4.1 The problem of packet classification 10.4.2 The tuple space search (TSS) algorithm 10.4.3 GPU-based TSS algorithm 10.4.4 TSS persistent kernel 10.4.5 Experimental results 10.5 Conclusion and future directions References Inspec keywords: Big Data; microprocessor chips; graphics processing units Other keywords: GPUs; CPUs; graphics processing units; packet processing; Big Data; heterogeneous platforms Subjects: Microprocessor chips; Data handling techniques

We present a visualization application that enables effective interactive visual analysis of large-scale 3D histopathology, that is, high-resolution 3D microscopy data of human tissue. Clinical work flows and research based on pathology have, until now, largely been dominated by 2D imaging. As we will show in the paper, studying volumetric histology data will open up novel and useful opportunities for both research and clinical practice. Our starting point is the current lack of appropriate visualization tools in histopathology, which has been a limiting factor in the uptake of digital pathology. Visualization of 3D histology data does pose difficult challenges in several aspects. The full-color datasets are dense and large in scale, on the order of 100,000 × 100,000× 100 voxels. This entails serious demands on both rendering performance and user experience design. Despite this, our developed application supports interactive study of 3D histology datasets at native resolution. Our application is based on tailoring and tuning of existing methods, system integration work, as well as a careful study of domain specific demands emanating from a close participatory design process with domain experts as team members. Results from a user evaluation employing the tool demonstrate a strong agreement among the 14 participating pathologists that 3D histopathology will be a valuable and enabling tool for their work.

Objective: Peripheral bone mineral density (BMD) may be decreased in early rheumatoid arthritis (RA) but it is unknown whether BMD loss emerges before arthritis is clinically apparent. We aimed to study whether BMD loss occurs in patients with clinically suspect arthralgia (CSA), and whether it is associated with progression to clinical arthritis and magnetic resonance imaging (MRI)-detected subclinical inflammation.Method: Patients with CSA had arthralgia for <1 year and were at risk of progressing to RA according to their rheumatologists. At baseline, a 1.5 T MRI was performed of unilateral metacarpophalangeal, wrist, and metatarsophalangeal joints, and scored on synovitis, bone marrow oedema, and tenosynovitis;. summing these features yielded the total MRI inflammation score. Digital X-ray radiogrammetry (DXR) was used to estimate BMD on two sequential conventional hand radiographs (mean interval between radiographs 4.4 months). The change in BMD was studied; BMD loss was defined as a decrease of ≥2.5 mg/cm2/month. Patients were followed for arthritis development for a median of 18.4 months.Results: In CSA patients (n = 108), change in BMD was negatively associated with age (β = −0.03, p = 0.007). BMD loss in CSA patients was associated with arthritis development [adjusted for age hazard ratio (HR) = 6.1, 95% confidence interval (CI) 1.7 to 21.4] and was most frequently estimated in the months before clinical arthritis development. The total MRI inflammation scores were associated with the change in BMD (adjusted for age β = −0.05, p = 0.047). The total MRI inflammation score and BMD loss were both independently associated with arthritis development (HR = 1.1, 95% CI 1.1 to 1.2, and HR = 4.6, 95% CI 1.2 to 17.2, respectively).Conclusion: In CSA patients, severe BMD loss is associated with MRI-detectable subclinical inflammation and with progression to clinical arthritis.

Autopsies constitute a valuable feedback to the healthcare chain to achieve improvements in quality of care and cost effectiveness. This review describes post-mortem imaging, which has emerged as an important part of the pathology toolbox. A broad range of visualization aspects within post-mortem imaging are covered. General state-of-the-art overviews of the components in the visualization pipeline are complemented by in-depth descriptions of methods developed by the authors and our collaborators. The forensic field is represented and related to, as it is spearheading much development in post-mortem imaging. Other topics are workflow, imaging data acquisition, and visualization rendering technology. All in all, this review shows the mature state of visual analysis for a non- or minimal-invasive investigation of the deceased patient.

We present a method for accurate image registration and motion estimation in multidimensional volumes, such as 3D CT and MR images. The method is based on phase from quadrature filters, which makes it insensitive to variations in luminance and other disturbance in the images. The theory is not restricted to any particular kind of motion model or number of dimensions. Experimental results for affine motions in 3D show high accuracy.

ABSTRACT We present data on a first prototype for photon counting tomosynthesis imaging of small children, which we call photon-counting tomosynthesis (PCT). A photon counting detector can completely eliminate electronic noise, which makes it ideal for tomosynthesis because of the low dose in each projection. Another advantage is that the detector allows for energy sensitivity in later versions, which will further lower the radiation dose. In-plane resolution is high and has been measured to be 5 lp/mm, at least 4 times better than in CT, while the depth resolution was significantly lower than typical CT resolution. The image SNR decreased from 30 to 10 for a detail of 10 mm depth in increasing thickness of PMMA from 10 to 80 mm. The air kerma measured for PCT was 5.2 mGy, which leads to an organ dose to the brain of approximately 0.7 mGy. This dose is 96 % lower than a typical CT dose. PCT can be appealing for pediatric imaging since young children have an increased sensitivity to radiation induced cancers. We have acquired post mortem images of a newborn with the new device and with a state-of-the-art CT and compared the diagnostic information and dose levels of the two modalities. The results are promising but more work is needed to provide input to a next generation prototype that would be suitable for clinical trials. Keywords: Tomosynthesis, photon counting, pediatric imaging