Convex optimization problem prototyping for image reconstruction in computed tomography with the Chambolle-Pock algorithm

The primal-dual optimization algorithm developed in Chambolle and Pock (CP), 2011 is applied to various convex optimization problems of interest in computed tomography (CT) image reconstruction. This algorithm allows for rapid prototyping of optimization problems for the purpose of designing iterative image reconstruction algorithms for CT. The primal-dual algorithm is briefly summarized in the article, and its potential for prototyping is demonstrated by explicitly deriving CP algorithm instances for many optimization problems relevant to CT. An example application modeling breast CT with low-intensity X-ray illumination is presented.Comment: Resubmitted to Physics in Medicine and Biology. Text has been modified according to referee comments, and typos in the equations have been correcte

The Biological Standard of Living in the two Germanies.

Physical stature is used as a proxy for the biological standard of living in the two Germanies before and after unification in an analysis of a cross-sectional sample (1998) of adult heights, as well as among military recruits of the 1990s. West Germans tended to be taller than East Germans throughout the period under consideration. Contrary to official proclamations of a classless society, there were substantial social differences in physical stature in East-Germany. Social differences in height were greater in the East among females, and less among males than in the West. The difficulties experienced by the East-German population after 1961 is evident in the increase in social inequality of physical stature thereafter, as well as in the increasing gap relative to the height of the West-German population. After unification, however, there is a tendency for East-German males, but not of females, to catch up with their West-German counterparts

Solid organ transplantation programs facing lack of empiric evidence in the COVID‐19 pandemic: A By‐proxy Society Recommendation Consensus approach

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has a drastic impact on national health care systems. Given the overwhelming demand on facility capacity, the impact on all health care sectors has to be addressed. Solid organ transplantation represents a field with a high demand on staff, intensive care units, and follow-up facilities. The great therapeutic value of organ transplantation has to be weighed against mandatory constraints of health care capacities. In addition, the management of immunosuppressed recipients has to be reassessed during the ongoing coronavirus disease 2019 (COVID-19) pandemic. In addressing these crucial questions, transplant physicians are facing a total lack of scientific evidence. Therefore, the aim of this study was to offer an approach of consensus-based guidance, derived from individual information of 22 transplant societies. Key recommendations were extracted and the degree of consensus among different organizations was calculated. A high degree of consensus was found for temporarily suspending nonurgent transplant procedures and living donation programs. Systematic polymerase chain reaction-based testing of donors and recipients was broadly recommended. Additionally, more specific aspects (eg, screening of surgical explant teams and restricted use of marginal donor organs) were included in our analysis. This study offers a novel approach to informed guidance for health care management when a priori no scientific evidence is available

A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT

While compressed sensing (CS) based reconstructions have been developed for low-dose CBCT, a clear understanding on the relationship between the image quality and imaging dose at low dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot image quality and imaging dose together as functions of number of projections and mAs per projection over the whole clinically relevant range. A clear understanding on the tradeoff between image quality and dose can be achieved and optimal low-dose CBCT scan protocols can be developed for various imaging tasks in IGRT. Main findings of this work include: 1) Under the CS framework, image quality has little degradation over a large dose range, and the degradation becomes evident when the dose < 100 total mAs. A dose < 40 total mAs leads to a dramatic image degradation. Optimal low-dose CBCT scan protocols likely fall in the dose range of 40-100 total mAs, depending on the specific IGRT applications. 2) Among different scan protocols at a constant low-dose level, the super sparse-view reconstruction with projection number less than 50 is the most challenging case, even with strong regularization. Better image quality can be acquired with other low mAs protocols. 3) The optimal scan protocol is the combination of a medium number of projections and a medium level of mAs/view. This is more evident when the dose is around 72.8 total mAs or below and when the ROI is a low-contrast or high-resolution object. Based on our results, the optimal number of projections is around 90 to 120. 4) The clinically acceptable lowest dose level is task dependent. In our study, 72.8mAs is a safe dose level for visualizing low-contrast objects, while 12.2 total mAs is sufficient for detecting high-contrast objects of diameter greater than 3 mm.Comment: 19 pages, 12 figures, submitted to Physics in Medicine and Biolog

Application of Photogrammetry in Biomedical Science

Peer reviewedPostprin

Trade blocs and trade wars during the interwar period

What precisely were the causes and consequences of the trade wars in the 1930s? Were there perhaps deeper forces at work in reorienting global trade prior to the outbreak of World War II? And what lessons may this particular historical episode provide for the present day? To answer these questions, we distinguish between long‐run secular trends in the period from 1920 to 1939 related to the formation of trade blocs and short‐run disruptions associated with the trade wars of the 1930s. We argue that the trade wars mainly served to intensify pre‐existing efforts toward the formation of trade blocs which dated from at least 1920. More speculatively, we argue that the trade wars of the present day may serve a similar purpose as those in the 1930s, that is, the intensification of China‐ and US‐centric trade blocs

Development of classification criteria for hand osteoarthritis: comparative analyses of persons with and without hand osteoarthritis

Objectives Further knowledge about typical hand osteoarthritis (OA) characteristics is needed for the development of new classification criteria for hand OA.Methods In a cross-sectional multi-centre international study, a convenience sample of patients from primary and secondary/tertiary care with a physician-based hand OA diagnosis (n = 128) were compared with controls with hand complaints due to inflammatory or non-inflammatory conditions (n = 70). We examined whether self-reported, clinical, radiographic and laboratory findings were associated with hand OA using logistic regression analyses. Discrimination between groups was assessed by calculating the area under receiver operating curves (AUC).Results Strong associations with hand OA were observed for radiographic osteophytes (OR = 1.62, 95% CI 1.40 to 1.88) and joint space narrowing (JSN) (OR = 1.57, 95% CI 1.36 to 1.82) in the distal interphalangeal (DIP) joints with excellent discrimination (AUC = 0.82 for both). For osteophytes and JSN, we found acceptable discrimination between groups in the proximal interphalangeal joints (AUC = 0.77 and 0.78, respectively), but poorer discrimination in the first carpometacarpal joints (AUC = 0.67 and 0.63, respectively). Painful DIP joints were associated with hand OA, but were less able to discriminate between groups (AUC = 0.67). Age and family history of OA were positively associated with hand OA, whereas negative associations were found for pain, stiffness and soft tissue swelling in metacarpophalangeal joints, pain and marginal erosions in wrists, longer morning stiffness, inflammatory biomarkers and autoantibodies.Conclusions Differences in symptoms, clinical findings, radiographic changes and laboratory tests were found in patients with hand OA versus controls. Radiographic OA features, especially in DIP joints, were best suited to discriminate between groups.Clinical epidemiolog

EULAR recommendations for the non-pharmacological management of systemic lupus erythematosus and systemic sclerosis

Objective To develop evidence-based recommendations for the non-pharmacological management of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). Methods A task force comprising 7 rheumatologists, 15 other healthcare professionals and 3 patients was established. Following a systematic literature review performed to inform the recommendations, statements were formulated, discussed during online meetings and graded based on risk of bias assessment, level of evidence (LoE) and strength of recommendation (SoR; scale AD , A comprising consistent LoE 1 studies, D comprising LoE 4 or inconsistent studies), following the European Alliance of Associations for Rheumatology standard operating procedure. Level of agreement (LoA; scale 0-10, 0 denoting complete disagreement, 10 denoting complete agreement) was determined for each statement through online voting. Results Four overarching principles and 12 recommendations were developed. These concerned common and disease-specific aspects of non-pharmacological management. SoR ranged from A to D. The mean LoA with the overarching principles and recommendations ranged from 8.4 to 9.7. Briefly, non-pharmacological management of SLE and SSc should be tailored, person-centred and participatory. It is not intended to preclude but rather complement pharmacotherapy. Patients should be offered education and support for physical exercise, smoking cessation and avoidance of cold exposure. Photoprotection and psychosocial interventions are important for SLE patients, while mouth and hand exercises are important in SSc. Conclusions The recommendations will guide healthcare professionals and patients towards a holistic and personalised management of SLE and SSc. Research and educational agendas were developed to address needs towards a higher evidence level, enhancement of clinician-patient communication and improved outcomes