Electrocardiographic Gating and Cerebral Perfusion Computed Tomography Option-Set Prevalence and Utilization Data From 62 Institutions in the United States.

OBJECTIVES: To provide the radiology community with data to address the question: "Compared with peer institutions, is my institution efficiently using its electrocardiographic (ECG) gating and cerebral perfusion-capable computed tomography (CT) scanners?" METHODS: In this retrospective study, we analyze 6 months of scanner utilization data from 62 institutions (299 locations, 507 scanners) to identify scanners capable of performing ECG gating and perfusion CT studies. We report the number of ECG gating/perfusion-capable scanners and locations as a function of the total number of locations and scanners in each institution. We additionally regress the number of ECG-gated and perfusion examinations on (1) the number of locations/scanners capable of performing these examinations and (2) the fraction of the institution's CT examination volume that requires ECG gating or perfusion. We provide look-up tables so an institution can compare its ECG-gated/perfusion examination volume to other institutions with similar ECG-gated/perfusion examination fractions and capable scanners. RESULTS: We detected an effect of both ECG-gating examination fraction and the number of ECG gating-capable scanners on ECG-gated examination volume ( χ21 = 77.5 [ P < 0.001] and χ21 = 64.2 [ P < 0.001], respectively). Similar results were obtained for perfusion examination fraction and perfusion-capable scanners as they relate to perfusion examination volume ( χ21 = 51.6 [ P < 0.001] and χ21 = 45.2 [ P < 0.001], respectively). The number of ECG gating/perfusion-capable scanners and locations within an institution were found to positively correlate with both the total number of locations and scanners within an institution ( P < 0.001 for all hypothesis tests). CONCLUSIONS: The study provides multi-institutional data on ECG gating and perfusion examination volumes that can be used to inform CT purchasing decisions.

Multicentric study of patients receiving 50 or 100 mSv in a single day through CT imaging-frequency determination and imaging protocols involved.

OBJECTIVES: To assess the magnitude and characterization of CT imaging protocols of patients receiving 50 or 100 mSv in a single day. METHODS: In this multicentric retrospective study covering up to 279 hospitals from January 2015 to December 2019, the effective dose (E) as estimated by dose management system from dose length product of patients was filtered and grouped into per-day dose bands (≤ 20, > 20-50, > 50-70, > 70-100, > 100-200, > 200 mSv). Information on patient's age and imaging protocol was noted. The data were analyzed to determine the frequency of occurrence in each dose band. Top 20 CT imaging protocols that led to patients with a dose of ≥ 50 mSv in a single acquisition were identified and their relative frequency was estimated. RESULTS: A total of approx. 4.3 million (4,283,738) CT exams were performed in approx. 3.9 million (3,880,524) patient-days indicating 9.41% had more than one CT exam in a single day. There were 31,058 (0.8%) patient-days with ≥ 50 mSv and 1191 (0.03%) with ≥ 100 mSv. Nearly 1/3rd patient-days reaching ≥ 50 mSv were of patients aged 50 years or younger. The top 20 CT imaging protocols that led to ≥ 50 mSv in a single day belonged to the body region (chest or abdomen and pelvis) and nearly one-third were angiographic studies. CONCLUSIONS: In the first study of its kind, we report that patients with 50 mSv+ in a single day or a single exam are not rare. The information on imaging protocols leading to such doses and their frequency has been provided to help develop dose management strategies. KEY POINTS: • Our study of 4,283,738 CT exams performed in 3,880,524 patient-days indicates 0.8% with 50 mSv+ and 0.03% with 100 mSv+ in a single day. • A total of 9.41% underwent more than one CT exam in a single day; nearly 1/3rd of those with 50 mSv+ were ≤ 50 years of age. • Identified top 20 CT imaging protocols that led to 50 mSv+ doses in a single exam. All belong to chest or abdomen and pelvis and nearly 1/3rd were angiographic studies.

Clinical concordance with Image Gently guidelines for pediatric computed tomography: a study across 663,417 CT scans at 53 clinical facilities.

BACKGROUND: Managing patient radiation dose in pediatric computed tomography (CT) examinations is essential. Some organizations, most notably Image Gently, have suggested techniques to lower dose to pediatric patients and mitigate risk while maintaining image quality. OBJECTIVE: We sought to validate whether institutions are observing Image Gently guidelines in practice. MATERIALS AND METHODS: Dose-relevant data from 663,417 abdomen-pelvis and chest CT scans were obtained from 53 facilities. Patients were assigned arbitrary age cohorts with a minimum size of n=12 patients in each age group, for statistical purposes. All pediatric (<19 years old) cohorts at a given facility were compared to the adult cohort by a Kruskal-Wallis test for each of the four scan parameters - (1) x-ray tube kilovoltage (kV), (2) tube-current-by-exposure-time product (tube mAs), (3) scan pitch and (4) tube rotation time - to assess whether the distribution of values in the pediatric cohorts differed from the adult cohort. The same was repeated with volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) to assess whether pediatric cohorts received less dose than adult cohorts. A P-value of <0.05 was deemed significant. RESULTS: Across the 150 pediatric cohorts, 134 had scan parameters that were more child-sized than their adult counterparts. In 128 of these 134 pediatric cohorts, the CTDIvol was less than the adult counterpart. In 111 of these 128 pediatric cohorts, the SSDE was less than the adult counterpart. CONCLUSION: The study reaffirms that in practice, Image Gently's suggestions of lowering tube mAs and peak kilovoltage are commonly employed and effective at reducing pediatric CT dose.

Patients undergoing recurrent CT scans: assessing the magnitude.

OBJECTIVES: To assess percent of patients undergoing multiple CT exams that leads to cumulative effective dose (CED) of ≥ 100 mSv and determine their age distribution. METHODS: Data was retrieved retrospectively from established radiation dose monitoring systems by setting the threshold value of 100 mSv at four institutions covering 324 hospitals. The number of patients with CED ≥ 100 mSv only from recurrent CT exams during a feasible time period between 1 and 5 years was identified. Age and gender distribution of these patients were assessed to identify the magnitude of patients in the relatively lower age group of ≤ 50 years. RESULTS: Of the 2.5 million (2,504,585) patients who underwent 4.8 million (4,819,661) CT exams during the period of between 1 and 5 years, a total of 33,407 (1.33%) patients received a CED of ≥ 100 mSv with an overall median CED of 130.3 mSv and maximum of 1185 mSv. Although the vast majority (72-86%) of patients are > 50 years of age, nearly 20% (13.4 to 28%) are ≤ 50 years. The minimum time to accrue 100 mSv was a single day at all four institutions, an unreported finding to date. CONCLUSIONS: We are in an unprecedented era, where patients undergoing multiple CT exams and receiving CED ≥ 100 mSv are not uncommon. While underscoring the need for imaging appropriateness, the consideration of the number and percent of patients with high exposures and related clinical necessities creates an urgent need for the industry to develop CT scanners and protocols with sub-mSv radiation dose, a goal that has been lingering. KEY POINTS: • We are in an era where patients undergoing multiple CT exams during a short span of 1 to 5 years are not uncommon and a sizable fraction among them are below 50 years of age. • This leads to cumulative radiation dose to individual patients at which radiation effects are of real concern. • There is an urgent need for the industry to develop CT scanners with sub-mSv radiation dose, a goal that has been lingering.

An engineered GFP fluorescent bacterial biosensor for detecting and quantifying silver and copper ions.

Presented here are two engineered bacterial biosensors for detecting and quantifying silver and copper ions. The biosensors contain a silver/copper resistance operon and a Green Fluorescent Protein gene that is strictly regulated through silver activated promoter regions normally found on a silver resistance gene (sil operon). The two biosensors efficiently detected silver and copper concentrations of 40 µM-300 µM and 20 µM-600 µM respectively. A strong correlation (R2 = 0.90 or above) between silver/copper and GFP signal makes it possible to quantify the ions using a linear regression. At room temperature incubation, the GFP signal of the biosensors in Ag+ saturated after 13 h. However, a detectable GFP signal was seen in 4 h.

The Completed PacBio Single-Molecule Real-Time Sequence of Methylosinus trichosporium Strain OB3b Reveals the Presence of a Third Large Plasmid.

Presented here is the complete genome sequence of the well-studied Rhizobiales methanotroph Methylosinus trichosporium strain OB3b. The assembly contains 5,183,433 bp, corresponding to a chromosome of 4,508,832 bp and three circular plasmids of 285,280 bp, 209,102 bp, and 180,219 bp.

Fluorocopolymer-coated nitinol self-expanding paclitaxel-eluting stent: pharmacokinetics and vascular biology responses in a porcine iliofemoral model.

AIMS: Our aim was to evaluate arterial responses to paclitaxel and a novel fluorocopolymer-coated nitinol low-dose paclitaxel-eluting stent (FP-PES). METHODS AND RESULTS: Human smooth muscle cell (SMC) migration was assessed after exposure to paclitaxel in vitro. For pharmacokinetics and vascular response, FP-PES or bare metal stents (BMS) were implanted in porcine iliofemoral arteries. Paclitaxel significantly inhibited human coronary and femoral artery SMC migration at doses as low as 1 pM. Inhibition was significantly greater for femoral compared with coronary artery SMCs from 1 pM to 1 µM. Pharmacokinetics showed consistent paclitaxel release from FP-PES over the study duration. The peak arterial wall paclitaxel level was 3.7 ng/mg at 10 days, with levels decreasing to 50% of peak at 60 days and 10% at 180 days. Paclitaxel was not detected in blood or remote organs. Arteriogram and histomorphometry analyses showed FP-PES significantly inhibits neointimal proliferation versus BMS at 30 and 90 days. Re-endothelialisation scores were not different between groups. CONCLUSIONS: Paclitaxel affected femoral artery SMC migration at lower concentrations and to a greater degree than it did coronary artery SMCs. The novel FP-PES used in this preclinical study demonstrated a vascular healing response similar to BMS, while significantly inhibiting neointimal formation up to 90 days.

Comparative Effectiveness Research: Alternatives to "Traditional" Computed Tomography Use in the Acute Care Setting.

Computed tomography (CT) scanning is an essential diagnostic tool and has revolutionized care of patients in the acute care setting. However, there is widespread agreement that overutilization of CT, where benefits do not exceed possible costs or harms, is occurring. The goal was to seek consensus in identifying and prioritizing research questions and themes that involve the comparative effectiveness of "traditional" CT use versus alternative diagnostic strategies in the acute care setting. A modified Delphi technique was used that included input from emergency physicians, emergency radiologists, medical physicists, and an industry expert to achieve this.

Psychosocial factors in sports injury rehabilitation and return to play.

This article discusses the principles and practices that guide psychological intervention with injury, and encourages a psychological approach to injury for clinicians. Part 1 reviews the research literature, and serves as a foundation for the review of clinical practices in part 2. Examination of the research literature highlights 4 areas: (1) psychological factors influencing rehabilitation, (2) social factors affecting rehabilitation, (3) performance concerns among returning athletes, and (4) tools/inventories for assessing psychological readiness to return. A synopsis of an injury intervention plan is provided, and the influence of pain and fear in the rehabilitation process is described.

Site-specific bacterial chromosome engineering: ΦC31 integrase mediated cassette exchange (IMCE).

The bacterial chromosome may be used to stably maintain foreign DNA in the mega-base range. Integration into the chromosome circumvents issues such as plasmid replication, plasmid stability, plasmid incompatibility, and plasmid copy number variance. This method uses the site-specific integrase from the Streptomyces phage (Φ) C31. The ΦC31 integrase catalyzes a direct recombination between two specific DNA sites: attB and attP (34 and 39 bp, respectively). This recombination is stable and does not revert. A "landing pad" (LP) sequence consisting of a spectinomycin-resistance gene, aadA (SpR), and the E. coli ß-glucuronidase gene (uidA) flanked by attP sites has been integrated into the chromosomes of Sinorhizobium meliloti, Ochrobactrum anthropi, and Agrobacterium tumefaciens in an intergenic region, the ampC locus, and the tetA locus, respectively. S. meliloti is used in this protocol. Mobilizable donor vectors containing attB sites flanking a stuffer red fluorescent protein (rfp) gene and an antibiotic resistance gene have also been constructed. In this example the gentamicin resistant plasmid pJH110 is used. The rfp gene may be replaced with a desired construct using SphI and PstI. Alternatively a synthetic construct flanked by attB sites may be sub-cloned into a mobilizable vector such as pK19mob. The expression of the ΦC31 integrase gene (cloned from pHS62) is driven by the lac promoter, on a mobilizable broad host range plasmid pRK7813. A tetraparental mating protocol is used to transfer the donor cassette into the LP strain thereby replacing the markers in the LP sequence with the donor cassette. These cells are trans-integrants. Trans-integrants are formed with a typical efficiency of 0.5%. Trans-integrants are typically found within the first 500-1,000 colonies screened by antibiotic sensitivity or blue-white screening using 5-bromo-4-chloro-3-indolyl-beta-D-glucuronic acid (X-gluc). This protocol contains the mating and selection procedures for creating and isolating trans-integrants.

The fluorescence theatre: a cost-effective device using theatre gels for fluorescent protein and dye screening.

Here we report a simple cost-effective device for screening colonies on plates for expression of the monomeric red fluorescent protein mRFP1 and the fluorescent dye Nile red. This device can be built from any simple light source, in our case a Quebec Colony Counter, and cost-effective theatre gels. The device can be assembled in as little as 20 min, and it produces excellent results when screening a large number of colonies.

A prospective evaluation of the safety and efficacy of the TAXUS Element paclitaxel-eluting coronary stent system for the treatment of de novo coronary artery lesions: design and statistical methods of the PERSEUS clinical program.

BACKGROUND: Paclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation paclitaxel-eluting stent which incorporates a novel, thinner-strut, platinum-enriched metal alloy platform. The stent is intended to have enhanced radiopacity and improved deliverability compared to other paclitaxel-eluting stents. The safety and efficacy of the TAXUS Element stent are being evaluated in the pivotal PERSEUS clinical trials. METHODS/DESIGN: The PERSEUS trials include two parallel studies of the TAXUS Element stent in single, de novo coronary atherosclerotic lesions. The PERSEUS Workhorse study is a prospective, randomized (3:1), single-blind, non-inferiority trial in subjects with lesion length < or = 28 mm and vessel diameter > or = 2.75 mm to < or = 4.0 mm which compares TAXUS Element to the TAXUS Express2 paclitaxel-eluting stent system. The Workhorse study employs a novel Bayesian statistical approach that uses prior information to limit the number of study subjects exposed to the investigational device and thus provide a safer and more efficient analysis of the TAXUS Element stent. PERSEUS Small Vessel is a prospective, single-arm, superiority trial in subjects with lesion length < or = 20 mm and vessel diameter > or = 2.25 mm to <2.75 mm that compares TAXUS Element with a matched historical bare metal Express stent control. DISCUSSION: The TAXUS PERSEUS clinical trial program uses a novel statistical approach to evaluate whether design and metal alloy iterations in the TAXUS Element stent platform provide comparable safety and improved procedural performance compared to the previous generation Express stent. PERSEUS trial enrollment is complete and primary endpoint data are expected in 2010. PERSEUS Workhorse and Small Vessel are registered at http://www.clinicaltrials.gov, identification numbers NCT00484315 and NCT00489541.

Identification of sport and recreational activity concussion history through the preparticipation screening and a symptom survey in young athletes.

OBJECTIVE: To evaluate the concussion history of young athletes using three questions on the preparticipation screening (PPS) and a concussion symptom survey (CSS). DESIGN: Descriptive survey. SETTING: Mass high school PPS. PATIENTS OR OTHER PARTICIPANTS: Five hundred twenty young athletes. INTERVENTIONS: Athletes were asked about their concussion history using three different questions on the PPS. The CSS, a list of concussion-related symptoms, was also given to assess the history of concussion-related symptoms associated with a previous injury to the head. MAIN OUTCOME MEASURES: Positive concussion history was determined as a positive response on one of the three PPS questions or any one of the CSS responses and reported as frequencies and percentages. Kappa coefficients were used to evaluate the agreement between the responses on the three PPS questions. RESULTS: There was little agreement among the three PPS questions, with kappa coefficients ranging from kappa = -0.018 to 0.342. Analysis of the CSS revealed that 286 athletes (55.0%) reported having at least one concussion symptom after a head injury. Of those reporting symptoms, 86.4% did not report a concussion history in sport, and 92.7% did not report a concussion history in recreational activities. CONCLUSIONS: The identification of concussion history may depend on the phrasing of questions on the PPS. Simply asking an athlete whether they had a concussion may not adequately identify athletes with concussion histories. Although recommendations have been made to avoid the terminology of ding and bell rung, it seems these terms may be needed to ensure adequate reporting of previous concussions in young athletes.