Region-Adaptive Deformable Registration of CT/MRI Pelvic Images via Learning-Based Image Synthesis

Registration of pelvic CT and MRI is highly desired as it can facilitate effective fusion of two modalities for prostate cancer radiation therapy, i.e., using CT for dose planning and MRI for accurate organ delineation. However, due to the large inter-modality appearance gaps and the high shape/appearance variations of pelvic organs, the pelvic CT/MRI registration is highly challenging. In this paper, we propose a region-adaptive deformable registration method for multi-modal pelvic image registration. Specifically, to handle the large appearance gaps, we first perform both CT-to-MRI and MRI-to-CT image synthesis by multi-target regression forest (MT-RF). Then, to use the complementary anatomical information in the two modalities for steering the registration, we select key points automatically from both modalities and use them together for guiding correspondence detection in the region-adaptive fashion. That is, we mainly use CT to establish correspondences for bone regions, and use MRI to establish correspondences for soft tissue regions. The number of key points is increased gradually during the registration, to hierarchically guide the symmetric estimation of the deformation fields. Experiments for both intra-subject and inter-subject deformable registration show improved performances compared with state-of-the-art multi-modal registration methods, which demonstrate the potentials of our method to be applied for the routine prostate cancer radiation therapy

Pelvic Organ Segmentation Using Distinctive Curve Guided Fully Convolutional Networks

Accurate segmentation of pelvic organs (i.e., prostate, bladder, and rectum) from CT image is crucial for effective prostate cancer radiotherapy. However, it is a challenging task due to: 1) low soft tissue contrast in CT images and 2) large shape and appearance variations of pelvic organs. In this paper, we employ a two-stage deep learning-based method, with a novel distinctive curve-guided fully convolutional network (FCN), to solve the aforementioned challenges. Specifically, the first stage is for fast and robust organ detection in the raw CT images. It is designed as a coarse segmentation network to provide region proposals for three pelvic organs. The second stage is for fine segmentation of each organ, based on the region proposal results. To better identify those indistinguishable pelvic organ boundaries, a novel morphological representation, namely, distinctive curve, is also introduced to help better conduct the precise segmentation. To implement this, in this second stage, a multi-task FCN is initially utilized to learn the distinctive curve and the segmentation map separately and then combine these two tasks to produce accurate segmentation map. The final segmentation results of all three pelvic organs are generated by a weighted max-voting strategy. We have conducted exhaustive experiments on a large and diverse pelvic CT data set for evaluating our proposed method. The experimental results demonstrate that our proposed method is accurate and robust for this challenging segmentation task, by also outperforming the state-of-the-art segmentation methods

Targeted next-generation sequencing of dedifferentiated chondrosarcoma in the skull base reveals combined TP53 and PTEN mutations with increased proliferation index, an implication for pathogenesis

Dedifferentiated chondrosarcoma (DDCS) is a rare disease with a dismal prognosis. DDCS consists of two morphologically distinct components: the cartilaginous and noncartilaginous components. Whether the two components originate from the same progenitor cells has been controversial. Recurrent DDCS commonly displays increased proliferation compared with the primary tumor. However, there is no conclusive explanation for this mechanism. In this paper, we present two DDCSs in the sellar region. Patient 1 exclusively exhibited a noncartilaginous component with a TP53 frameshift mutation in the pathological specimens from the first surgery. The tumor recurred after radiation therapy with an exceedingly increased proliferation index. Targeted next-generation sequencing (NGS) revealed the presence of both a TP53 mutation and a PTEN deletion in the cartilaginous and the noncartilaginous components of the recurrent tumor. Fluorescence in situ hybridization and immunostaining confirmed reduced DNA copy number and protein levels of the PTEN gene as a result of the PTEN deletion. Patient 2 exhibited both cartilaginous and noncartilaginous components in the surgical specimens. Targeted NGS of cells from both components showed neither TP53 nor PTEN mutations, making Patient 2 a naïve TP53 and PTEN control for comparison. In conclusion, additional PTEN loss in the background of the TP53 mutation could be the cause of increased proliferation capacity in the recurrent tumor

Dual-core steered non-rigid registration for multi-modal images via bi-directional image synthesis

In prostate cancer radiotherapy, computed tomography (CT) is widely used for dose planning purposes. However, because CT has low soft tissue contrast, it makes manual contouring difficult for major pelvic organs. In contrast, magnetic resonance imaging (MRI) provides high soft tissue contrast, which makes it ideal for accurate manual contouring. Therefore, the contouring accuracy on CT can be significantly improved if the contours in MRI can be mapped to CT domain by registering MRI with CT of the same subject, which would eventually lead to high treatment efficacy. In this paper, we propose a bi-directional image synthesis based approach for MRI-to-CT pelvic image registration. First, we use patch-wise random forest with auto-context model to learn the appearance mapping from CT to MRI domain, and then vice versa. Consequently, we can synthesize a pseudo-MRI whose anatomical structures are exactly same with CT but with MRI-like appearance, and a pseudo-CT as well. Then, our MRI-to-CT registration can be steered in a dual manner, by simultaneously estimating two deformation pathways: 1) one from the pseudo-CT to the actual CT and 2) another from actual MRI to the pseudo-MRI. Next, a dual-core deformation fusion framework is developed to iteratively and effectively combine these two registration pathways by using complementary information from both modalities. Experiments on a dataset with real pelvic CT and MRI have shown improved registration performance of the proposed method by comparing it to the conventional registration methods, thus indicating its high potential of translation to the routine radiation therapy

Ten-year Development of General Practice in China：Opportunities and Challenges

ObjectiveTo review the strengths and limitations of the development of general practice in China during the last decade (2010—2020) and to assess the opportunities and challenges for its future development.MethodsData were collected from statistic reports, journal articles and official policies and guidelines regarding general practice development in China from 2010—2020. Donabedian model was applied to examine and assess the quality of essential general practice services in China. SWOT analysis was used to identify internal and external determinants of general practice development in China.Results(1) Structural quality of general practice: the ten-year policies about general practice development were a continuation of the past relevant policies in essence but with developments, with highlights on continuous construction of general practice workforce and discipline, tiered diagnosis and treatment and regional medical consortium, but relevant fiscal and management policies still need improvements. The number of general medical workers has increased rapidly, while the lion's share of them are still allocated at tertiary hospitals. Full-time equivalent is suggested to be used to predict the staffing and assess the performance of these workers. The number of community health centres showed a steady increase, but its growth rate was still slower than that of hospital facilities. Relevant health economics data need to be further supplemented. (2) Process quality of general practice: in 2020, there were 2.045 billion visits in community health centers (stations) and township health centers, that is, 1.5 visits per person per year on average. There was a significant development when found only 1 visit per person per year for primary care in 2010. However, the frequency of visits for primary care was still lower than that of visiting hospital-based outpatients (an average of 2.7 visits per person per year) . The COVID-19 pandemic had a significant impact on community health services/general medical services, and the number of outpatient visits dropped by about 20%. The number of general practice research articles reached a peak in 2018, mainly focusing on bi-directional referrals, tiered diagnosis and treatment, general practitioners (GPs) /family doctors, general medicine, community health services, chronic disease management (especially hypertension and diabetes) , and analysis of factors associated with aspects involved in general medical services. General practice research is expected to provide more support for developing innovative and critical thoughts, more practice-based evidence for clinical services, and more assistance for service quality and patient outcomes improvement as the discipline advances. (3) Results of implementing general medical services: there is no sufficient evidence on the influence of general medical services on people's health. The experiences and views of people including healthy individuals and patients indicated that those receiving general medical services or contracted family doctor services perceived positive experience and expressed high satisfaction, but perceptions and views of general population in the community toward general medical services need to be explored. GPs' own experience and opinions on general practice were quite different. Gender, age, professional title, urban and rural areas, and geographical location may be associated with their experience and job satisfaction. There may be instability in the general practice workforce, mainly due to personal income, workload and time pressure. (4) The major strengths of developing general practice in China are as follows: strong policy-based promotion and government leadership; rapidly constructing and developing GPs teams owing to the excellent resource allocating ability shown by the centralized system from central to all local governments; significantly enhanced general practice education and training systems; increased core professionals as general practice educators and trainers; special development of general practice characterized by the integration of medical sciences and Chinese traditional humanistic theories. (5) The development of general practice in China has been facing limitations similar to those in other countries. Besides that, its special limitations include late development of the discipline, unsatisfactory quality of workforce, high work pressure and high prevalence of burnout in the workforce, as well as impact of generation gap on education and practice among GPs. In addition, the relation between specialists and GPs is on transition of from undifferentiated attachment to self-recognised uniquity, and further seeking transdisciplinary. The teaching competences of GPs teachers, especially those teaching community and clinical care, are inadequate. GPs team building and management need to advance from the formation to the storming and performing phases. (6) Opportunities for further development of general practice in China include strategies for achieving the goals of Healthy China, and an all-round well-off society, the important role of primary health care in sustainable development and universal health coverage reaffirmed by the Declaration of Astana, as well as significantly improved health literacy of people. (7) Challenges for the development of general practice in China include population ageing, and aging-related changes in burden of disease and socio-economic status, the aging and dynamic changes of GPs human resources, the variation of urban and rural areas and regional differences, and the inverted pyramid structure of allocation of medical and health resources (namely, the largest part is allocated to tertiary care while the smallest to primary care) . Relevant recommendations to address these challenges comprise strengthening the advocacy of the development of general practice services, establishing a wide-ranging community collaborative network, and developing general practice professional organizations.ConclusionThe development of general practice in China is advancing, which is manifested as rapidly increased number of general medical workers, strong government promotion, quickly improved accessibility of essential medical services, and notably increased utilization rate of primary care services. However, the development is facing challenges, such as high discipline and social expectations regarding general practice, instability in the workforce due to high work pressure of the knowledge- and labor-intensive job, GPs' insufficient recognition of their self-identity, and unclear status of financial funding for general practice development. Given that there are unprecedented favorable conditions for general practice development, medical industries and general medical workers are suggested to make efforts to turn challenges into opportunities to develop general medical services, thereby universal health outcomes will be improved

Natural Environment Suitability of China and Its Relationship with Population Distributions

The natural environment factor is one of the main indexes for evaluating human habitats, sustained economic growth and ecological health status. Based on Geographic Information System (GIS) technology and an analytic hierarchy process method, this article presents the construction of the Natural Environment Suitability Index (NESI) model of China by using natural environment data including climate, hydrology, surface configuration and ecological conditions. The NESI value is calculated in grids of 1 km by 1 km through ArcGIS. The spatial regularity of NESI is analyzed according to its spatial distribution and proportional structure. The relationship of NESI with population distribution and economic growth is also discussed by analyzing NESI results with population distribution data and GDP data in 1 km by 1 km grids. The study shows that: (1) the value of NESI is higher in the East and lower in the West in China; The best natural environment area is the Yangtze River Delta region and the worst are the northwest of Tibet and southwest of Xinjiang. (2) There is a close correlation among natural environment, population distribution and economic growth; the best natural environment area, the Yangtze River Delta region, is also the region with higher population density and richer economy. The worst natural environment areas, Northwest and Tibetan Plateau, are also regions with lower population density and poorer economies

Air pollution–aerosol interactions produce more bioavailable iron for ocean ecosystems

It has long been hypothesized that acids formed from anthropogenic pollutants and natural emissions dissolve iron (Fe) in airborne particles, enhancing the supply of bioavailable Fe to the oceans. However, field observations have yet to provide indisputable evidence to confirm this hypothesis. Single-particle chemical analysis for hundreds of individual atmospheric particles collected over the East China Sea shows that Fe-rich particles from coal combustion and steel industries were coated with thick layers of sulfate after 1 to 2 days of atmospheric residence. The Fe in aged particles was present as a “hotspot” of (insoluble) iron oxides and throughout the acidic sulfate coating in the form of (soluble) Fe sulfate, which increases with degree of aging (thickness of coating). This provides the “smoking gun” for acid iron dissolution, because iron sulfate was not detected in the freshly emitted particles and there is no other source or mechanism of iron sulfate formation in the atmosphere