Magnetic resonance imaging frequently changes classification of acute traumatic thoracolumbar spine injuries

Objective: To evaluate the influence of additional (MRI) compared with computed tomography (CT) alone for the classification of traumatic spinal injuries using the Arbeitsgemeinshaft für Osteosynthesefragen (AO) system and the Thoraco-Lumbar Injury Classification and Severity (TLICS) scale. Materials and methods: Images from 100 consecutive patients with at least one fracture on CT were evaluated retrospectively by three radiologists with regard to the AO and TLICS classification systems in 2 steps. First, all images from the initial CT examination were analyzed. Second, 6weeks later, CT and MR images were analyzed together. Descriptive statistics and Wilcoxon tests were performed to identify changes in the number of fractures and ligamentous lesions detected and their corresponding classification. Results: CT and MRI together revealed a total of 196 fractures (CT alone 162 fractures). The AO classification changed in 31%, the TLICS classification changed in 33% of the patients compared with CT alone. Based on CT and MRI together, the TLICS value changed from values < 5 (indication for conservative therapy) to values ≥ 5 (indication for surgical therapy) in 24%. Conclusion: MRI of patients with thoracolumbar spinal trauma considerably improved the detection of fractures and soft tissue injuries compared with CT alone and significantly changed the overall trauma classificatio

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements