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When main-sequence stars expand into red giants, they are expected to engulf close-in planets1-5. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants6-8 has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars9. Here we present the discovery that the giant planet 8 Ursae Minoris b10 orbits a core-helium-burning red giant. At a distance of only 0.5 AU from its host star, the planet would have been engulfed by its host star, which is predicted by standard single-star evolution to have previously expanded to a radius of 0.7 AU. Given the brief lifetime of helium-burning giants, the nearly circular orbit of the planet is challenging to reconcile with scenarios in which the planet survives by having a distant orbit initially. Instead, the planet may have avoided engulfment through a stellar merger that either altered the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet11. This system shows that core-helium-burning red giants can harbour close planets and provides evidence for the role of non-canonical stellar evolution in the extended survival of late-stage exoplanetary systems.

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BACKGROUND: American youth football leagues are typically structured using either age-only (AO) or age-and-weight (AW) playing standard conditions. These playing standard conditions group players by age in the former condition and by a combination of age and weight in the latter condition. However, no study has systematically compared injury risk between these 2 playing standards. PURPOSE: To compare injury rates between youth tackle football players in the AO and AW playing standard conditions. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Athletic trainers evaluated and recorded injuries at each practice and game during the 2012 and 2013 football seasons. Players (age, 5-14 years) were drawn from 13 recreational leagues across 6 states. The sample included 4092 athlete-seasons (AW, 2065; AO, 2027) from 210 teams (AW, 106; O, 104). Injury rate ratios (RRs) with 95% CIs were used to compare the playing standard conditions. Multivariate Poisson regression was used to estimate RRs adjusted for residual effects of age and clustering by team and league. There were 4 endpoints of interest: (1) any injury, (2) non-time loss (NTL) injuries only, (3) time loss (TL) injuries only, and (4) concussions only. RESULTS: Over 2 seasons, the cohort accumulated 1475 injuries and 142,536 athlete-exposures (AEs). The most common injuries were contusions (34.4%), ligament sprains (16.3%), concussions (9.6%), and muscle strains (7.8%). The overall injury rate for both playing standard conditions combined was 10.3 per 1000 AEs (95% CI, 9.8-10.9). The TL injury, NTL injury, and concussion rates in both playing standard conditions combined were 3.1, 7.2, and 1.0 per 1000 AEs, respectively. In multivariate Poisson regression models controlling for age, team, and league, no differences were found between playing standard conditions in the overall injury rate (RRoverall, 1.1; 95% CI, 0.4-2.6). Rates for the other 3 endpoints were also similar (RRNTL, 1.1 [95% CI, 0.4-3.0]; RRTL, 0.9 [95% CI, 0.4-1.9]; RRconcussion, 0.6 [95% CI, 0.3-1.4]). CONCLUSION: For the injury endpoints examined in this study, the injury rates were similar in the AO and AW playing standards. Future research should examine other policies, rules, and behavioral factors that may affect injury risk within youth football.

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OBJECTIVE: The aim of this study was to quantitatively and qualitatively evaluate pulmonary 64-MDCT angiography image quality in pregnancy and puerperium, compared with female nonpregnant control subjects. MATERIALS AND METHODS: The study group comprised 124 consecutive pregnant and postpartum women and 124 female nonpregnant control subjects who presented with suspected pulmonary embolism. The individual studies were evaluated for subjective and objective diagnostic quality. RESULTS: Objective measurements of the arterial enhancement in the pulmonary trunk and left and right pulmonary arteries found that there was no statistically significant difference in attenuation values between the pregnant and puerperium group and the control group for pulmonary artery opacification. The mean attenuation in the pulmonary trunk was 270.54 HU in the pregnant group, 277.53 HU in the puerperium group, and 293.90 HU in the control group. CONCLUSION: We found no significant difference in diagnostic quality of pulmonary CT angiography using MDCT between the study and control groups. The use of MDCT acquisition, faster injection rates, higher contrast medium concentration, and higher trigger levels may decrease the number of nondiagnostic studies in this population. MDCT may be a worthwhile investigation in the majority of pregnant patients with suspected pulmonary embolism.

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INTRODUCTION: Clinically unsuspected pulmonary embolism (PE) can be detected in oncology patients undergoing computed tomography (CT) imaging for reasons other than for PE diagnosis, but there is little prospective data on its true prevalence, clinical importance, or on methods to improve detection. METHODS: In consecutive oncology patients undergoing CT imaging of the chest for indications other than PE detection, CT pulmonary angiography (CTPA) was systematically included as part of the imaging protocol. Each imaging study was prospectively analyzed for the presence of PE. A 6-month follow-up was performed. Institutional review board approval was obtained. RESULTS: Four hundred seven oncology patients were included. Indications for chest CT imaging included baseline staging (31%), restaging after therapy (53%), routine surveillance (15%), or assessment of extrathoracic disease (1%). Clinically unsuspected PE were detected in 18 patients (4.4%). The prevalence of unsuspected PE was 6.4% among inpatients and 3.4% among outpatients. PE was more prevalent among patients with metastatic disease (7% versus 2%, p = 0.007) and in patients who had received recent chemotherapy (11% versus 3%, p = 0.008). In 7 (39%) of the 18 patients with clinically unsuspected PE, emboli were only identifiable on the CTPA study and not on the routine chest CT study. The diagnosis of PE led to immediate changes in patient management. CONCLUSION: Clinically unsuspected PE is present in up to 4.4% of oncology patients undergoing CT imaging for indications other than PE diagnosis. Modifying standard CT imaging protocols to include a CTPA examination optimizes their detection and leads to changes in patient management.

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OBJECTIVE: To assess the feasibility and utility of magnetic resonance (MR) imaging of the bowel in concurrent small- and large-bowel evaluation for the presence of inflammatory bowel disease (IBD). METHODS: Over a 5-year period, 62 MR examinations performed on 53 patients demonstrated evidence of IBD. Sixteen of these 53 (30.1%) patients had imaging findings of colonic disease and underwent 19 formal MR small bowel examinations. These were further evaluated for bowel distention and image quality. The sensitivity and specificity of the technique compared with colonoscopy as the 'gold standard' was evaluated. RESULTS: Simultaneous imaging of the colon is feasible at MR small bowel follow-through with moderate-to-excellent colonic visibility and colon distention obtained when the contrast medium is present in the colon at the time of image acquisition. MR imaging had a sensitivity of 80% (0.56-0.93), specificity of 100% (0.77-1.00), positive predictive value (PPV) of 1 and a negative predictive value (NPV) of 0.8 for the identification of colitis (based on available concurrent correlation of 38/62 examinations with colonoscopy). CONCLUSION: Small and large bowel MR imaging with orally consumed contrast medium represents a promising, feasible, non-invasive, non-radiating single mode of assessment of the entire gastrointestinal tract, performed at a single sitting.

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PURPOSE: To assess the normal small bowel parameters, namely bowel diameter, bowel wall thickness, number of folds (valvulae connivientes) per 2.5 cm (in.), fold thickness and interfold distance per small bowel segment (duodenum, jejunum, proximal ileum, distal ileum and terminal ileum) on MR enterography. MATERIALS AND METHODS: Between September 2003 and January 2008, 280 MR enterography examinations were performed for investigation of known or suspected small bowel pathology. 120 of these examinations were normal. Sixty-five (m=29, f=36, mean age=34 years, range=17-73 years) of 120 examinations without a prior small bowel diagnosis, with no prior or subsequent abnormal radiology or endoscopy examinations, no prior small bowel surgery and with a minimum 3 years follow-up demonstrating normality were retrospectively evaluated for the described small bowel parameters. RESULTS: We found the mean diameter of the duodenum to be 24.8mm (S.D.=4.5mm), jejunum to be 24.5mm (S.D.=4.2mm), proximal ileum to be 19.5mm (S.D.=3.6mm), distal ileum to be 18.9 mm (S.D.=4.2mm) and terminal ileum to be 18.7 mm (S.D.=3.6mm). The number of folds per 2.5 cm varied from 4.6 in the jejunum to 1.5 in the terminal ileum. The fold thickness varied from 2.1mm in the duodenum to 1.8mm in the terminal ileum. The small bowel parameters gradually decreased in size from the duodenum to the smallest measurements which were in the terminal ileum. The bowel wall is similar in size throughout the small bowel measuring 1.5+/-0.5mm. CONCLUSION: These results provide the mean, range of normality and standard deviation of the small bowel parameters per segment on the current population on MR enterography. From our experience, knowledge of these parameters is extremely helpful and essential in the everyday assessment of MR enterography studies.

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OBJECTIVE: The purpose of our study was to evaluate the potential role of an MR small-bowel follow-through (SBFT) technique in the investigation of suspected pediatric small-bowel abnormalities. MATERIALS AND METHODS: Between September 2003 and January 2008, 280 MR SBFT examinations were performed for investigation of known or suspected small-bowel abnormalities, including 19 of 280 examinations in 17 children (mean age, 13 years; age range 6-17 years), representing the current study population. A standardized technique was used in all cases, including axial and coronal steady-state free precession acquisitions at successive time intervals until completion. Retrospective analysis of the studies obtained was performed by two radiologists, who blindly and independently scored predefined small-bowel segments according to the degree of luminal distention achieved. Any pathologic lesions detected were also noted. Indicators of examination success as a whole (volume, tolerability, and side effects of oral contrast material) were also noted, as were details pertaining to examination duration (number of visits to the MR table, total table time). RESULTS: Oral contrast medium was ingested and subsequent imaging was possible in all patients; 84.2% of patients tolerated the oral contrast material well and 15.8% showed moderate tolerance. The MR table time ranged from 2 to 4 minutes, without early termination of the examination in any case. The average number of visits to the MR table was 1.3 (range, 1-3). The mean duration for complete small-bowel evaluation was 25 minutes (range, 20-60 minutes). The mean distention scores were well within the diagnostic range in all small-bowel segments for both observers, with a substantial degree of interobserver agreement in score assignment (kappa = 0.73). Pathologic lesions were identified in 53% of studies. CONCLUSION: MR SBFT represents a promising, and perhaps optimal, technique for pediatric small-bowel evaluation for a variety of reasons, including its high tolerability, lack of ionizing radiation, avoidance of duodenojejunal intubation, and excellent luminal distention achieved. Furthermore, this technique allows "pseudodynamic" functional imaging while also showing extraluminal disease, without known biologic risk.

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To date, cross-sectional imaging of the duodenum has a number of inadequacies, most likely a reflection of its tortuous and complex anatomical course, resulting in somewhat suboptimal imaging. The purpose of this study was to describe and assess the feasibility of performing a 'tubeless', per-oral, single contrast, hypotonic magnetic resonance (MR) duodenography technique. Secondly, to assess the efficacy of intravenous Buscopan in facilitating duodenal distension at cross-sectional MR imaging. Ten healthy volunteers prospectively underwent MR imaging of the duodenum pre- and post-Buscopan immediately after consuming 1,000 ml of water. Images were qualitatively (using a visual assessment grading scale of 1-3) and quantitatively evaluated with regard to degree of small bowel distension by two observers. The contrast medium was successfully ingested and MR examination was completed in all participants. Quantitatively and qualitatively, the per-oral, hypotonic duodenography technique yielded superior distension scores and was significantly greater in diameter in comparison with the per-oral non-hypotonic duodenography technique (p < 0.003, p < 0.002). Per-oral, single-contrast, hypotonic MR duodenography is a feasible, simple, fast mode of investigation of the duodenum, which does not involve radiation and represents a useful technique in the armamentarium of the radiologist.

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OBJECTIVE: The cross-sectional characterization of duodenal abnormalities is plagued with inadequacy, a reflection of the meandering course of this segment of the bowel. We consider the imaging appearance of such abnormalities at MRI small-bowel follow-through, illustrating the typical manifestations of each pathologically confirmed condition. CONCLUSION: MRI small-bowel follow-through allows confident duodenal evaluation because of a combination of sufficient luminal distention and multiplanar versatility. Diseases of the duodenum may have a variety of manifestations at MRI small-bowel follow-through, the knowledge of which may aid in confident noninvasive patient diagnosis.

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OBJECTIVE: Retroperitoneal fibrosis is a rare collagen vascular disorder of unclear cause. Both benign and malignant associations have been described, rendering differentiation of these entities of paramount importance because sinister pathology alters the diagnosis. Thus, a high level of diligence is required in the investigation of this condition, particularly in patients with concomitant systemic conditions. CONCLUSION: Familiarity with the realm of imaging manifestations of retroperitoneal fibrosis is vital to ensure correct diagnosis and optimal treatment.

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OBJECTIVE: The purpose of this study was to assess whether prone or supine imaging provides superior small-bowel loop distention during MRI small-bowel follow-through examinations and whether either position is better with regard to lesion detection and evaluation. SUBJECTS AND METHODS: Forty consecutively enrolled clinically referred patients with known or suspected small-bowel abnormalities prospectively underwent 62 MRI small-bowel follow-through examinations in both the prone and the supine positions. Images were blindly and independently reviewed by two observers. Each small-bowel segment was assessed with a 3-point scoring system, and differences in bowel distention in the prone and supine positions were evaluated with a paired Wilcoxon's test. Differences between rates of lesion detection and characterization (e.g., ulceration, stricturing) were analyzed with a paired Student's t test. Interobserver agreement was estimated with the kappa coefficient. RESULTS: In both normal and diseased small bowel, the prone position had statistically significantly higher distention scores than did the supine position (p < 0.05) with a high level of interobserver agreement. This finding, however, did not translate into improved lesion detection or characterization (p > 0.05). CONCLUSION: Although use of the prone position results in superior small-bowel distention during MRI small-bowel follow-through, both the prone and supine positions are equal in terms of lesion detection and feature visualization.

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OBJECTIVE: The objective of our study was to evaluate the morphologic appearances of small-bowel lymphoma using MR enterography to identify key morphologic traits capable of providing an association between imaging manifestations and likely histologic diagnosis. MATERIALS AND METHODS: Over a 54-month period, 10 patients with subsequently confirmed small-bowel lymphoma were imaged using a standardized MR enterography technique. Retrospective chart review was performed to detect associated disease processes, such as celiac disease. The morphologic characteristics of each segment with lymphomatous involvement were evaluated with respect to tumor location, tumor size, mural characteristics, fold features, loop dilatation, luminal stricturing, mesenteric or antimesenteric distribution, mesenteric involvement, and signal intensity. RESULTS: Nineteen distinct segments of lymphomatous involvement were identified in 10 patients, and underlying celiac disease was confirmed in six of the 10 patients. This patient group comprised 10 patients with non-Hodgkin's lymphoma (NHL) of various subtypes. No cases of Hodgkin's lymphoma were encountered. Analysis revealed celiac NHL enteropathy to have a tendency toward localization to a single, long (> 10 cm), smooth continuous bowel segment, often with aneurysmal loop dilatation, in the absence of a distinct mesenteric or antimesenteric distribution. Luminal stricturing was encountered in cases of low-grade lymphoma, whereas mesenteric fat infiltration represented a characteristic of high-grade disease. CONCLUSION: We describe the characteristics of small-bowel lymphoma on MR enterography, identifying a number of key features that may help the interpreting radiologist in suggesting the underlying histologic subtype and whether the presence of underlying celiac disease is likely.

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We report the case of a patient with multiple myeloma (MM) and extensive lytic bone disease who presented with a short history of back pain and leg weakness. Magnetic resonance imaging (MRI) of the lumbar spine revealed a sacral insufficiency fracture complicated by an epidural haematoma. Bleeding tendency in this case can be accounted for by platelet function defects, often described in plasma cell disorders in the absence of obvious coagulation abnormalities. Surgical intervention was contraindicated as a result of poor overall patient performance status (poor surgical candidate due to extensive myelomatous bone disease, previous vertebral compression fractures requiring orthopaedic stabilisation, and requiring opiate analgesia for bone pain) and management was conservative. Patients presenting with back pain and documented bone disease in the setting of myeloma should be managed with a high index of clinical suspicion and considered for urgent MR imaging to avoid missing this serious and potentially reversible complication. We report the undescribed causative association between sacral insufficiency fracture and lumbo-sacral epidural haematoma. We illustrate the MRI signal and contrast enhancement pattern of an acute presentation of epidural haematoma.

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OBJECTIVE: The purpose of our study was to determine the prevalence of unsuspected venous thromboembolic disease--specifically, of pulmonary embolism (PE) and of inferior vena cava (IVC), iliac, and iliofemoral deep venous thromboses (DVTs)--in oncology patients on staging CT scans of the thorax, abdomen, and pelvis. MATERIALS AND METHODS: Retrospective analysis was performed on 435 consecutive staging CT thorax, abdomen, and pelvis scans performed on a variety of oncology patients for the presence of venous thromboembolic disease. The patient group consisted of 198 men and 237 women who ranged in age from 20 to 79 years (mean, 55 years). Disease type, stage, concomitant surgery or chemoradiation therapy regimes, anticoagulation status, and 6-month clinical and radiologic follow-up findings were recorded. RESULTS: We found a prevalence of 6.8% (23/339) unsuspected iliofemoral, 1.2% (4/339) unsuspected common iliac, and 0.3% (1/315) unsuspected IVC DVTs and 3.3% (13/397) unsuspected PEs occurring in patients with a wide range of malignancies. The overall prevalence of unsuspected venous thromboembolism (i.e., DVT, PE, or both) was 6.3% (25/397). DVT, PE, and venous thromboembolic disease were more common in inpatients (p = 0.002, 0.004, 0.023; relative risk [RR] = 1.6, 2.1, 1.4, respectively) and in those with advanced disease (p = 0.001, 0.01, 0.001; RR = 2.2, 1.8, 2.0, respectively). CONCLUSION: Although there is a known increased risk of thromboembolism (DVT and PE) in oncology patients, many cases are not diagnosed, which can prove fatal. Staging CT simultaneously affords one sole investigation of the pulmonary, IVC, iliac, and upper femoral veins, thereby providing an important diagnostic opportunity. Assessment for DVT and PE is important when reviewing staging CT scans.

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Evaluation of gastric wall pathology using cross-sectional imaging has proved difficult, particularly in the imaging of early, localized disease. The properties of Calogen as a negative oral contrast agent for the evaluation of the upper gastro-intestinal tract and retroperitoneum in CT has been well described. We assess the suitability of this agent as an oral contrast medium for use in MRI examination of the gastric wall, finding the mean scores for Calogen and water with regard to gastric distension to be 8.46 and 5.49, respectively (P < 0.01). Concerning obliteration of mucosal detail, the respective scores are 8.48 and 3.84 (P < 0.01). Calogen is also statistically superior to water with regard to prevention of peristalsis and homogeneity (mean scores 8.15 vs. 5.74 and 8.69 vs. 6.30, respectively). Oral Calogen, therefore, is superior to water as an oral contrast agent for MRI examination of the gastric wall. Its ingestion allows identification of the gastric wall with fat intensity material on both sides, further aiding characterisation of subtle mural anomalies.

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