Does 3T Fetal MRI Improve Image Resolution of Normal Brain Structures between 20 and 24 Weeks' Gestational Age?

BACKGROUND AND PURPOSE: Stronger magnetic fields have the potential to improve fetal image resolution. Our objective was to detect whether there was better anatomic resolution of brain structures in fetuses imaged with a 3T magnet compared with a 1.5T magnet. MATERIALS AND METHODS: Multiple cerebral and facial anatomic structures were retrospectively assessed in 28 fetal MR imaging scans with normal findings (12 at 3T and 16 at 1.5T) with a 0-3 grading score. Fetuses were assessed during the second trimesters (gestational age, 20-24 weeks). The association between the quality ratings and magnetic field strengths (1.5T versus 3T) was evaluated by a linear mixed-effects model. A quantitative assessment of the signal intensity was also performed in the different layers of the developing brain. Comparative log-ratios were calculated across the different layers of the fetal brain. RESULTS: There was a statistically significant interaction between location and magnetic field strength (P < .001). The cerebral structures of the cerebellum, pons, venous system, semicircular canal, and cochlea showed statistically significant higher values on the 3T magnet. Similarly, statistical significance was also obtained on the quantitative assessment of the multilayer appearance of the brain; the 3T magnet had a median factor of 8.38 higher than the 1.5T magnet (95% CI, 4.73-14.82). Other anatomic structures assessed in the supratentorial compartment of the brain showed higher values on the 3T magnet with no statistical significance. CONCLUSIONS: Both magnets depict cerebral and facial normal anatomic structures; however, our data indicates better anatomic detail on the 3T than on the 1.5T magnet.

h-Indices in a university department of anaesthesia: an evaluation of their feasibility, reliability, and validity as an assessment of academic performance.

BACKGROUND: The h-index is a tool that is increasingly used to measure individual research productivity. It is unknown whether its use as an evaluation of individual research impact is reliable and valid within the context of anaesthesia. METHODS: We calculated the h-indices of 268 faculty members of a university department of anaesthesia using Scopus™ and Web of Science(®). Agreement between the databases was investigated with a Bland-Altman plot. The construct validity was examined by comparing the h-indices for faculty grouped by academic rank. RESULTS: The mean bias between the Scopus™ and Web of Science(®) h-indices was 0.09 but 1.96 sd limits of agreement were -5.7 to 5.9. The Web of Science(®)-derived h-indices showed a statistically significant difference between the different academic ranks (P<0.001): median h-indices were 0 for lecturers, 2 for assistant professors, 9 for associate professors, and 16 for full professors. The Scopus™-derived h-indices also showed a statistically significant difference between the different academic ranks (P<0.001): median h-indices were 0 for lecturers, 1 for assistant professors, 9 for associate professors, and 17 for full professors. Post hoc testing found statistically significant differences in all comparisons between academic ranks (all P<0.01). Ignoring self-citations did not affect construct validity of the h-index. We found no evidence that the h-index is superior to counting the total number of publications. CONCLUSIONS: Agreement between the two databases was problematic. There was evidence of construct validity; however, the overlap between academic ranks limits the discriminative power of a low h-index.

Long term effects of a home visit to prevent childhood injury: three year follow up of a randomized trial.

OBJECTIVE: To assess the long term effect of a home safety visit on the rate of home injury. DESIGN: Telephone survey conducted 36 months after participation in a randomized controlled trial of a home safety intervention. A structured interview assessed participant knowledge, beliefs, or practices around injury prevention and the number of injuries requiring medical attention. SETTING: Five pediatric teaching hospitals in four Canadian urban centres. PARTICIPANTS: Children less than 8 years of age presenting to an emergency department with a targeted home injury (fall, scald, burn, poisoning or ingestion, choking, or head injury while riding a bicycle), a non-targeted injury, or a medical illness. RESULTS: We contacted 774 (66%) of the 1172 original participants. A higher proportion of participants in the intervention group (63%) reported that home visits changed their knowledge, beliefs, or practices around the prevention of home injuries compared with those in the non-intervention group (43%; p<0.001). Over the 36 month follow up period the rate of injury visits to the doctor was significantly less for the intervention group (rate ratio = 0.74; 95% CI 0.63 to 0.87), consistent with the original (12 month) study results (rate ratio = 0.69; 95% CI 0.54 to 0.88). However, the effectiveness of the intervention appears to be diminishing with time (rate ratio for the 12-36 month study interval = 0.80; 95% CI 0.64 to 1.00). CONCLUSIONS: A home safety visit was able to demonstrate sustained, but modest, effectiveness of an intervention aimed at improving home safety and reducing injury. This study reinforces the need of home safety programs to focus on passive intervention and a simple well defined message.

A randomized trial of tranexamic acid to reduce blood transfusion for scoliosis surgery.

UNLABELLED: Pediatric patients who undergo posterior spinal fusion surgery to correct scoliosis often require multiple blood transfusions. Tranexamic acid is a synthetic antifibrinolytic drug that reduces transfusion requirements in cardiac surgery and total knee arthroplasty. We evaluated the efficacy of prophylactic tranexamic acid to reduce perioperative blood transfusion requirements in a prospective, double-blinded, placebo control study. Forty patients, 9-18 yr of age, were randomized to either tranexamic acid (initial dose of 10 mg/kg and infusion of 1 mg. kg(-1). h(-1)) or placebo (isotonic saline). Perioperative management was standardized. A uniform transfusion threshold for noncell saved red blood cells was 7.0 g/dL. The total amount of blood transfused in the perioperative period was significantly reduced in the Tranexamic group (P = 0.045). No thrombotic complications were detected in either group. The administration of prophylactic tranexamic acid in patients with scoliosis undergoing posterior spinal fusion surgery has the potential to reduce perioperative blood transfusion requirements. IMPLICATIONS: The administration of prophylactic tranexamic acid in patients with scoliosis who are undergoing posterior spinal fusion surgery has the potential to reduce perioperative blood transfusion requirements.

Population dynamics of exploited fish stocks at low population levels.

Models of population dynamics in which per capita reproductive success declines at low population levels (variously known as depensation, the Allee effect, and inverse density-dependence) predict that populations can have multiple equilibria and may suddenly shift from one equilibrium to another. If such depensatory dynamics exist, reduced mortality may be insufficient to allow recovery of a population after abundance has been severely reduced by harvesting. Estimates of spawner abundance and number of surviving progeny for 128 fish stocks indicated only 3 stocks with significant depensation. Estimates of the statistical power of the tests strengthen the conclusion that depensatory dynamics are not apparent for fish populations at the levels studied.