Accuracy of Low Dose Computed Tomography Scanogram for Measurement of Femoral Version after Locked Intramedullary Nailing.

PURPOSE: This prospective study was performed to compare the accuracy of femoral version measurements following repair of femoral shaft fractures using computed tomography (CT) scanograms with 10 % of the standard dose of ionizing radiation versus standard-dose scanograms. METHODS: CT scanogram protocols that used 90 and 10 % of the usual dose of ionizing radiation were developed. Ten patients with comminuted femoral shaft fractures repaired with either an intramedullary (IM) nail or plate were imaged with both high- and low-dose CT scanograms. Postoperative version of both femurs was measured and compared between the two dose scans using the Bonesetter application. This was a prospective blinded controlled study at a level 1 trauma centre. Statistical analysis was performed, including standard deviation (SD) and paired t test. Significance was set at p < 0.05. RESULTS: Comparison of femoral version measurements between the 90 and 10 % dose scanograms on the native and repaired sides were insignificant (p = 0.870 and p = 0.737, respectively). The difference between native and repaired femurs had an average error of 2.0 ± 1.1° for both the high- and low-dose scans and was insignificant (p = 0.742). CONCLUSIONS: Reducing the dose of ionizing radiation in a CT scanogram by 90 % has no significant effect on the accuracy of femoral version measurement. This simple change can significantly reduce patient radiation exposure while accurately measuring femoral version and length.

MR characterization of hepatic storage iron in transfusional iron overload.

PURPOSE: To quantify the two principal forms of hepatic storage iron, diffuse, soluble iron (primarily ferritin), and aggregated, insoluble iron (primarily hemosiderin) using a new MRI method in patients with transfusional iron overload. MATERIALS AND METHODS: Six healthy volunteers and 20 patients with transfusion-dependent thalassemia syndromes and iron overload were examined. Ferritin- and hemosiderin-like iron were determined based on the measurement of two distinct relaxation parameters: the "reduced" transverse relaxation rate, RR2 , and the "aggregation index," A, using three sets of Carr-Purcell-Meiboom-Gill (CPMG) datasets with different interecho spacings. Agarose phantoms, simulating the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron, were used for validation. RESULTS: Both phantom and in vivo human data confirmed that transverse relaxation components associated with the dispersed and aggregated iron could be separated using the two-parameter (RR2 , A) method. The MRI-determined total hepatic storage iron was highly correlated (r = 0.95) with measurements derived from biopsy or biosusceptometry. As total hepatic storage iron increased, the proportion stored as aggregated iron became greater. CONCLUSION: This method provides a new means for noninvasive MRI determination of the partition of hepatic storage iron between ferritin and hemosiderin in iron overload disorders.

Ultrasound Examination Techniques for Elbow Injuries in Overhead Athletes.

Elbow pain is a frequent complaint among overhead athletes. Standard evaluation of the elbow uses history and physical examination, with radiographic imaging and MRI aiding in the confirmation of diagnosis. Musculoskeletal ultrasonography (US) provides dynamic, functional assessment of tendons and ligaments in the elbow, allowing the visualization of structures under stress and motion. Stress US offers the ability to detect injuries to the ulnar collateral ligament by measuring changes in joint space under stress. The freedom of dynamic imaging means results are dependent on the skill of the US operator to obtain the most accurate and complete evaluation. US is cost efficient and portable, allowing for quick examination at the point of care. This article provides a technique guide for sports medicine specialists performing US examination of the elbow.

Separate MRI quantification of dispersed (ferritin-like) and aggregated (hemosiderin-like) storage iron.

A new MRI method is proposed for separately quantifying the two principal forms of tissue storage (nonheme) iron: ferritin iron, a dispersed, soluble fraction that can be rapidly mobilized, and hemosiderin iron, an aggregated, insoluble fraction that serves as a long-term reserve. The method utilizes multiple spin echo sequences, exploiting the fact that aggregated iron can induce nonmonoexponential signal decay for multiple spin echo sequences. The method is validated in vitro for agarose phantoms, simulating dispersed iron with manganese chloride, and aggregated iron with iron oxide microspheres. To demonstrate feasibility for human studies, preliminary in vivo data from two healthy controls and six patients with transfusional iron overload are presented. For both phantoms and human subjects, conventional R(2) and R(2)* relaxation rates are also measured in order to contrast the proposed method with established MRI iron quantification techniques. Quantification of dispersed (ferritin-like) iron may provide a new means of monitoring the risk of iron-induced toxicity in patients with iron overload and, together with quantification of aggregated (hemosiderin-like) iron, improve the accuracy of estimates for total storage iron.

Gastrocnemius Injuries in Professional Baseball Players: An Epidemiological Study.

BACKGROUND: Gastrocnemius injuries are a common lower extremity injury in elite baseball players. There are no current epidemiological studies focused on gastrocnemius injuries in professional baseball players that provide information on the timing, distribution, and characteristics of such injuries. HYPOTHESIS: Gastrocnemius injury in professional baseball players is a common injury that is influenced by factors such as age, player position, and time of season. STUDY DESIGN: Descriptive epidemiological study. METHODS: Based on Major League Baseball's (MLB's) Health and Injury Tracking System (HITS) database, gastrocnemius injuries that caused time out of play for MLB and Minor League Baseball (MiLB) players during the 2011-2016 seasons were identified. Player characteristics, including age, level of play, and position at time of injury, were collected. Injury-specific factors analyzed included date of injury, time of season, days missed, and activity leading to injury. RESULTS: A total of 402 gastrocnemius injuries (n = 145, MLB; n = 257, MiLB) occurred during the 2011-2016 seasons. MLB players were significantly older at the time of injury (30.1 years, MLB; 23.9 years, MiLB; P < .001). Base running (36.1%) was the most common activity causing the injury, followed by fielding (23.6%), with 50.3% of base-running injuries sustained on the way to first base. In MLB players, gastrocnemius injuries were most common in infielders (48.3%), followed by pitchers (27.6%) and then outfielders (17.9%), while for MiLB players the injuries were more evenly distributed (33.5%, 28.8%, and 30.7%, respectively). The frequency of injuries in MLB players dropped off after the start of the regular season, whereas MiLB players had a consistent injury rate throughout the year. CONCLUSION: Gastrocnemius injuries are a common cause of lower extremity injury in professional baseball players, resulting in significant time out of play. Base running, particularly to first base, was the most common activity during injury. Outfielders had the fewest injuries; however, they required the longest time to recover. This study provides the first investigation to date with the HITS database to examine the characteristics and distribution of gastrocnemius injuries in professional baseball players, offering insight into risk factors, injury prevention, and recovery expectations.

Functional oligomers for the control and fixation of spatial organization in nanoparticle assemblies.

Interactions in nanoparticle assemblies play an important role in modulating their interesting magnetic and optical properties. Controlling and fixing the distance between nanoparticles is therefore crucial to the development of next-generation nanodevices. Here, we show that the interparticle distance in two-dimensional assemblies can be quantitatively controlled by functionalizing the nanoparticles with short polymers containing one functional end group that binds to the nanoparticle. Carboxy-functional poly(dimethylsiloxane) (PDMS) ligands are attached to the nanoparticle surface by a simple ligand exchange process with the oleic acid synthesis ligands. The distance between nanoparticles is manipulated by adjusting either the number of PDMS ligands per molecule or their molecular weight. The use of PDMS ligands is unique in that they provide a means to permanently and robustly fix the spatial distribution of nanoparticles because PDMS is readily converted to silicon oxide by a simple UV/ozone treatment. The distance between nanoparticles can be designed a priori, as it is found to scale well with theoretical predictions for the thickness of the surface-bound polymer brush layer.

Current progress in non-invasive imaging of beta cell mass of the endocrine pancreas.

The increasing incidence of diabetes requires a better understanding of the pathogenesis of the clinical disease. Studies in prevention and treatment have been hampered by the single end-point of diagnosis of diabetes and hyperglycemia. The common pathology in both type 1 and type 2 diabetes is insufficient beta-cell mass to meet the metabolic demand. Unfortunately, current diagnostic methods rely on metabolic responses that do not accurately reflect true beta-cell mass. Recent advances in beta-cell imaging have utilized multiple modalities in experimental and clinical settings. While no "gold-standard" exists to measure beta-cell mass, modalities such as single photon emission computed tomography, optical and fluorescent imaging, magnetic resonance imaging, and positron emission tomography have been used with mixed success. Many of the methods are limited by the inability to translate to the clinical setting, poor discrimination between the exocrine and endocrine pancreas, or a poor measurement of beta-cell mass. However, promising new "neurofunctional imaging" approaches have emerged as improved measures of beta-cell mass. We review the current understanding of the pathogenesis and evaluation of diabetes, as well as experimental approaches to assessing beta-cell mass.

Measurement and correction of stimulated echo contamination in T2-based iron quantification.

The purpose of this study was to characterize the effects of stimulated echo contamination on MR-based iron measurement derived from quantitative T2 images and develop a method for retrospective correction. Two multiple spin-echo (MSE) pulse sequences were implemented with different amounts of stimulated echo contamination. Agarose-based phantoms were constructed that simulate the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron. Additionally, myocardial iron was assessed in nine human subjects with transfusion iron overload. These data were used to determine the influence of stimulated echoes on iron measurements made by an MR-based iron quantification model that can separately measure dispersed and aggregated iron. The study found that stimulated echo contamination caused an underestimation of dispersed (ferritin-like) iron and an overestimation of aggregated (hemosiderin-like) iron when applying this model. The relationship between the measurements made with and without stimulated echo appears to be linear. The findings suggest that while it is important to use MSE sequences with minimal stimulated echo in T2-based iron quantification, it appears that data acquired with sub-optimal sequences can be retrospectively corrected using the methodology described here.

Targeting vascular amyloid in arterioles of Alzheimer disease transgenic mice with amyloid ß protein antibody-coated nanoparticles.

The relevance of cerebral amyloid angiopathy (CAA) to the pathogenesis of Alzheimer disease (AD) and dementia in general emphasizes the importance of developing novel targeting approaches for detecting and treating cerebrovascular amyloid (CVA) deposits. We developed a nanoparticle-based technology that uses a monoclonal antibody against fibrillar human amyloid-ß42 that is surface coated onto a functionalized phospholipid monolayer. We demonstrate that this conjugated nanoparticle binds to CVA deposits in arterioles of AD transgenic mice (Tg2576) after infusion into the external carotid artery using 3 different approaches. The first 2 approaches use a blood vessel enrichment of homogenized brain and a leptomeningeal vessel preparation from thin tangential brain slices from the surface of the cerebral cortex. Targeting of CVA by the antibody-coated nanoparticle was visualized using fluorescent lissamine rhodamine-labeled phospholipids in the nanoparticles, which were compared with fluorescent staining of the endothelial cells and amyloid deposits using confocal laser scanning microscopy. The third approach used high-field strength magnetic resonance imaging of antibody-coated iron oxide nanoparticles after infusion into the external carotid artery. Dark foci of contrast enhancement in cortical arterioles were observed in T2*-weighted images of ex vivo AD mouse brains that correlated histologically with CVA deposits. The targeting ability of these nanoparticles to CVA provides opportunities for the prevention and treatment of CAA.

Magnetic resonance imaging of major histocompatibility class II expression in the renal medulla using immunotargeted superparamagnetic iron oxide nanoparticles.

We demonstrate the development and successful application of immunotargeted superparamagnetic iron oxide nanoparticles (ITSIONs), with in vivo magnetic resonance diagnostic and potential drug delivery capability for kidney disease. Further, the versatility of the conjugation chemistry presents an attractive route to the preparation of a range of biomolecule-nanoparticle conjugates. The ITSION contrast agent is a stable, biocompatible, targeted nanoparticle complex that combines a monodisperse iron oxide nanoparticle core with a functionalized phospholipid coating conjugated to antibodies that is capable of targeting normal cells expressing specific target antigens. The plasma half-life and R1 and R2 relaxivities suggest sufficient time for targeted binding while clearing from the system quick enough for detection of specific contrast enhancement. RT1 anti-MHC Class II antibodies were used to target the renal medulla of the rat, a section of the kidney in which MHC Class II, associated with inflammation, is specifically expressed. For in vivo resonance imaging, we compare phospholipid coated nanoparticles, nonspecific ITSIONs, and RT1 ITSIONs. Enhanced binding of the RT1 ITSIONS indicates specificity for the renal medulla and thus potential for disease detection or drug delivery.