SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Virtopsy

515

 To report radiological findings observed in computed tomography (CT) and magnetic resonance imaging (MRI) scans of the first cases of congenital infection and microcephaly presumably associated with the Zika virus in the current Brazilian epidemic.

Concepts: Brain, Medical imaging, Nuclear magnetic resonance, Radiography, Magnetic resonance imaging, Radiology, Virtopsy, Case series

177

Imaging modalities including magnetic resonance imaging and X-ray computed tomography are established methods in daily clinical diagnosis of human brain. Clinical equipment does not provide sufficient spatial resolution to obtain morphological information on the cellular level, essential for applying minimally or non-invasive surgical interventions. Therefore, generic data with lateral sub-micrometer resolution have been generated from histological slices post mortem. Sub-cellular spatial resolution, lost in the third dimension as a result of sectioning, is obtained using magnetic resonance microscopy and micro computed tomography. We demonstrate that for human cerebellum grating-based X-ray phase tomography shows complementary contrast to magnetic resonance microscopy and histology. In this study, the contrast-to-noise values of magnetic resonance microscopy and phase tomography were comparable whereas the spatial resolution in phase tomography is an order of magnitude better. The registered data with their complementary information permit the distinct segmentation of tissues within the human cerebellum.

Concepts: Medicine, Brain, Medical imaging, Radiography, Magnetic resonance imaging, Cerebellum, Radiology, Virtopsy

163

Discrimination between simple and perforated appendicitis in patients with suspected appendicitis may help to determine the therapy, timing of surgery and risk of complications. The aim of this study was to estimate the accuracy of magnetic resonance imaging (MRI) in distinguishing between simple and perforated appendicitis, and to compare MRI against ultrasound imaging with selected additional (conditional) use of computed tomography (CT).

Concepts: Medical imaging, Nuclear magnetic resonance, Radiography, Magnetic resonance imaging, Radiology, Medical ultrasonography, Ultrasound, Virtopsy

28

We acquire the first experimental 3-D tomographic images with magnetic particle imaging (MPI) using projection reconstruction methodology, which is similar to algorithms employed in X-ray computed tomography. The primary advantage of projection reconstruction methods is an order of magnitude increase in signal-to-noise ratio (SNR) due to averaging. We first derive the point spread function, resolution, number of projections required, and the SNR gain in projection reconstruction MPI. We then design and construct the first scanner capable of gathering the necessary data for nonaliased projection reconstruction and experimentally verify our mathematical predictions. We demonstrate that filtered backprojection in MPI is experimentally feasible and illustrate the SNR and resolution improvements with projection reconstruction. Finally, we show that MPI is capable of producing three dimensional imaging volumes in both phantoms and postmortem mice.

Concepts: Medical imaging, Radiography, Tomographic reconstruction, Dimension, Euclidean space, Tomography, Virtopsy, Signal-to-noise ratio

27

OBJECTIVES: The principal aim of our study was to establish concordance between post-mortem CT (PMCT) and forensic standard autopsy (SA) in detecting lesions according to different anatomical regions. A secondary aim was to determine the efficacy of PMCT in showing lethal lesions. METHODS: PMCTs were compared with autopsies in 236 cadavers in different contexts of death. PMCT findings were assessed by two independent radiologists. RESULTS: Concordance between PMCT and autopsy was almost perfect in showing skull, basal skull and hyoid bone fractures as well as in detecting facial, vertebral or pelvic fractures. Both examinations were discordant in demonstrating some intracranial injuries, vascular or organ wounds (more findings showed by autopsy), as well in showing free air in anatomical cavities (more findings detected by PMCT). Moreover, PMCT was effective in determining lethal lesions in the context of craniofacial trauma or after a gunshot wound. Concordance between the findings of the two radiologists was almost perfect for each type of lesion. CONCLUSION: PMCT could be considered as effective as SA in determining the cause of death in certain traumatic events. It was also effective in showing lethal lesions and could be a useful tool in reducing the number of SA. KEY POINTS : • Post-mortem CT is increasingly performed as an alternative/adjunct to formal autopsy. • More modern CT systems provide greater anatomical scope. • PMCT can usually determine the cause of most deaths following trauma. • Prospective studies are still required to establish an algorithm for forensic CT.

Concepts: Bone, Death, Anatomical pathology, Injuries, Wound, Virtopsy, Autopsy, Embalming

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PURPOSE: The aim of this study was to compare the functional and structural outcomes of 2 techniques for double-row, suture-bridging cuff repair. METHODS: A consecutive series of 73 patients who underwent arthroscopic, double-row, suture-bridge primary rotator cuff repair of full-thickness supraspinatus tear were evaluated. Thirty-eight shoulders were repaired by the arthroscopic, tied, suture-bridging technique (group A), and 35 shoulders by knot-less bridging with suture tape material (group B). Constant scores, pain, range of motion, strength, and complications were measured after a minimum follow-up period of 12 months post-operatively. Structural integrity of the repairs was evaluated systematically by either magnetic resonance imaging or computed tomography arthrography. RESULTS: Median follow-up after surgery was 29 (23-32) months in group A, and 21 (12-23) months in group B. Mean pain relief, range of motion, strength, and constant score improved significantly in both groups. No statistical differences were found between groups in the post-operative period. According to control imaging, the re-tear rate trended to be higher in group A (23.4 %) than in group B (17.1 %), although not significantly. CONCLUSION: Both bridging repair techniques achieved successful functional outcomes. In terms of structural outcome, the knot-less tape-bridging construct showed a lower but not significant re-tear rate. Longer follow-up is needed to confirm these results and to evaluate potential differences between the two techniques. LEVEL OF EVIDENCE: A prospective, non-randomized, comparative study, Level III.

Concepts: Comparison, Medical imaging, Nuclear magnetic resonance, Radiography, Magnetic resonance imaging, Mean, Virtopsy, Rotator cuff

11

Background Many believe that fear of malpractice lawsuits drives physicians to order otherwise unnecessary care and that legal reforms could reduce such wasteful spending. Emergency physicians practice in an information-poor, resource-rich environment that may lend itself to costly defensive practice. Three states, Texas (in 2003), Georgia (in 2005), and South Carolina (in 2005), enacted legislation that changed the malpractice standard for emergency care to gross negligence. We investigated whether these substantial reforms changed practice. Methods Using a 5% random sample of Medicare fee-for-service beneficiaries, we identified all emergency department visits to hospitals in the three reform states and in neighboring (control) states from 1997 through 2011. Using a quasi-experimental design, we compared patient-level outcomes, before and after legislation, in reform states and control states. We controlled for characteristics of the patients, time-invariant hospital characteristics, and temporal trends. Outcomes were policy-attributable changes in the use of computed tomography (CT) or magnetic resonance imaging (MRI), per-visit emergency department charges, and the rate of hospital admissions. Results For eight of the nine state-outcome combinations tested, no policy-attributable reduction in the intensity of care was detected. We found no reduction in the rates of CT or MRI utilization or hospital admission in any of the three reform states and no reduction in charges in Texas or South Carolina. In Georgia, reform was associated with a 3.6% reduction (95% confidence interval, 0.9 to 6.2) in per-visit emergency department charges. Conclusions Legislation that substantially changed the malpractice standard for emergency physicians in three states had little effect on the intensity of practice, as measured by imaging rates, average charges, or hospital admission rates. (Funded by the Veterans Affairs Office of Academic Affiliations and others.).

Concepts: Hospital, Medical imaging, Nuclear magnetic resonance, Radiography, Magnetic resonance imaging, Urgent care, Virtopsy, Emergency department

4

Objective assessments of the shapes of various parts of the body can be made using images acquired with multidetector row computed tomography or magnetic resonance imaging. These images can be useful for understanding the changes in body shape that accompany aging.

Concepts: Spin, Medical imaging, Nuclear magnetic resonance, Radiography, Magnetic resonance imaging, Radiology, 2000s music groups, Virtopsy

4

Despite decades of research, and the growing healthcare and societal burden of chronic obstructive pulmonary disease (COPD), therapeutic COPD breakthroughs have not occurred. Sub-optimal COPD patient phenotyping, an incomplete understanding of COPD pathogenesis and a scarcity of sensitive tools that provide patient-relevant intermediate endpoints likely all play a role in the lack of new, efficacious COPD interventions. In other words, COPD patients are still diagnosed based on the presence of persistent airflow limitation measured using spirometry. Spirometry measurements reflect the global sum of all the different possible COPD pathologies and perhaps because of this, we lose sight of the different contributions of airway and parenchymal abnormalities. With recent advances in thoracic X-ray computed tomography (CT) and magnetic resonance imaging (MRI), lung structure and function abnormalities may be regionally identified and measured. These imaging endpoints may serve as biomarkers of COPD that can be used to better phenotype patients. Therefore, here we review novel CT and MRI measurements that help reveal COPD phenotypes and what COPD really ‘looks’ like, beyond spirometric indices. We discuss MR and CT imaging approaches for generating reproducible and sensitive measurements of COPD phenotypes related to pulmonary ventilation and perfusion as well as airway and parenchyma anatomical and morphological features. These measurements may provide a way to advance the development and testing of new COPD interventions and therapies.

Concepts: Asthma, Lung, Medical imaging, Radiography, Magnetic resonance imaging, Chronic obstructive pulmonary disease, Spirometry, Virtopsy

4

Segmentation of anatomical structures, from modalities like computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound, is a key enabling technology for medical applications such as diagnostics, planning and guidance. More efficient implementations are necessary, as most segmentation methods are computationally expensive, and the amount of medical imaging data is growing. The increased programmability of graphic processing units (GPUs) in recent years have enabled their use in several areas. GPUs can solve large data parallel problems at a higher speed than the traditional CPU, while being more affordable and energy efficient than distributed systems. Furthermore, using a GPU enables concurrent visualization and interactive segmentation, where the user can help the algorithm to achieve a satisfactory result. This review investigates the use of GPUs to accelerate medical image segmentation methods. A set of criteria for efficient use of GPUs are defined and each segmentation method is rated accordingly. In addition, references to relevant GPU implementations and insight into GPU optimization are provided and discussed. The review concludes that most segmentation methods may benefit from GPU processing due to the methods' data parallel structure and high thread count. However, factors such as synchronization, branch divergence and memory usage can limit the speedup.

Concepts: X-ray, Medical imaging, Radiography, Magnetic resonance imaging, Radiology, Parallel computing, Ultrasound, Virtopsy