Personalized Feedback on Staff Dose in Fluoroscopy-Guided Interventions: A New Era in Radiation Dose Monitoring

Radiation safety and protection are a key component of fluoroscopy-guided interventions. We hypothesize that providing weekly personal dose feedback will increase radiation awareness and ultimately will lead to optimized behavior. Therefore, we designed and implemented a personalized feedback of procedure and personal doses for medical staff involved in fluoroscopy-guided interventions. Medical staff (physicians and technicians, n = 27) involved in fluoroscopy-guided interventions were equipped with electronic personal dose meters (PDMs). Procedure dose data including the dose area product and effective doses from PDMs were prospectively monitored for each consecutive procedure over an 8-month period (n = 1082). A personalized feedback form was designed displaying for each staff individually the personal dose per procedure, as well as relative and cumulative doses. This study consisted of two phases: (1) 1-5th months: Staff did not receive feedback (n = 701) and (2) 6-8th months: Staff received weekly individual dose feedback (n = 381). An anonymous evaluation was performed on the feedback and occupational dose. Personalized feedback was scored valuable by 76% of the staff and increased radiation dose awareness for 71%. 57 and 52% reported an increased feeling of occupational safety and changing their behavior because of personalized feedback, respectively. For technicians, the normalized dose was significantly lower in the feedback phase compared to the prefeedback phase: [median (IQR) normalized dose (phase 1) 0.12 (0.04-0.50) A mu Sv/Gy cm(2) versus (phase 2) 0.08 (0.02-0.24) A mu Sv/Gy cm(2), p = 0.002]. Personalized dose feedback increases radiation awareness and safety and can be provided to staff involved in fluoroscopy-guided interventions

Three-dimensional T1 mapping of the mouse heart using variable flip angle steady-state MR imaging

Cardiac MR T(1) mapping is a promising quantitative imaging tool for the diagnosis and evaluation of cardiomyopathy. Here, we present a new preclinical cardiac MRI method enabling three-dimensional T(1) mapping of the mouse heart. The method is based on a variable flip angle analysis of steady-state MR imaging data. A retrospectively triggered three-dimensional FLASH (fast low-angle shot) sequence (3D IntraGate) enables a constant repetition time and maintains steady-state conditions. 3D T(1) mapping of the complete mouse heart could be achieved in 20 min. High-quality, bright-blood T(1) maps were obtained with homogeneous T(1) values (1764 ± 172 ms) throughout the myocardium. The repeatability coefficient of R(1) (1/T(1) ) in a specific region of the mouse heart was between 0.14 and 0.20 s(-1) , depending on the number of flip angles. The feasibility for detecting regional differences in ΔR(1) was shown with pre- and post-contrast T(1) mapping in mice with surgically induced myocardial infarction, for which ΔR(1) values up to 0.83 s(-1) were found in the infarct zone. The sequence was also investigated in black-blood mode, which, interestingly, showed a strong decrease in the apparent mean T(1) of healthy myocardium (905 ± 110 ms). This study shows that 3D T(1) mapping in the mouse heart is feasible and can be used to monitor regional changes in myocardial T(1), particularly in relation to pathology and in contrast-enhanced experiments to estimate local concentrations of (targeted) contrast agen

Embryonic cardiomyocyte, but not autologous stem cell transplantation, restricts infarct expansion, enhances ventricular function, and improves long-term survival

Controversy exists in regard to the beneficial effects of transplanting cardiac or somatic progenitor cells upon myocardial injury. We have therefore investigated the functional short- and long-term consequences after intramyocardial transplantation of these cell types in a murine lesion model. Myocardial infarction (MI) was induced in mice (n = 75), followed by the intramyocardial injection of 1-2×10(5) luciferase- and GFP-expressing embryonic cardiomyocytes (eCMs), skeletal myoblasts (SMs), mesenchymal stem cells (MSCs) or medium into the infarct. Non-treated healthy mice (n = 6) served as controls. Bioluminescence and fluorescence imaging confirmed the engraftment and survival of the cells up to seven weeks postoperatively. After two weeks MRI was performed, which showed that infarct volume was significantly decreased by eCMs only (14.8±2.2% MI+eCM vs. 26.7±1.6% MI). Left ventricular dilation was significantly decreased by transplantation of any cell type, but most efficiently by eCMs. Moreover, eCM treatment increased the ejection fraction and cardiac output significantly to 33.4±2.2% and 22.3±1.2 ml/min. In addition, this cell type exclusively and significantly increased the end-systolic wall thickness in the infarct center and borders and raised the wall thickening in the infarct borders. Repetitive echocardiography examinations at later time points confirmed that these beneficial effects were accompanied by better survival rates. Cellular cardiomyoplasty employing contractile and electrically coupling embryonic cardiomyocytes (eCMs) into ischemic myocardium provoked significantly smaller infarcts with less adverse remodeling and improved cardiac function and long-term survival compared to transplantation of somatic cells (SMs and MSCs), thereby proving that a cardiomyocyte phenotype is important to restore myocardial functio

MRI of ICAM-1 upregulation after stroke: the importance of choosing the appropriate target-specific particulate contrast agent

Magnetic resonance imaging (MRI) with targeted contrast agents provides a promising means for diagnosis and treatment monitoring after cerebrovascular injury. Our goal was to demonstrate the feasibility of this approach to detect the neuroinflammatory biomarker intercellular adhesion molecule-1 (ICAM-1) after stroke and to establish a most efficient imaging procedure. We compared two types of ICAM-1-functionalized contrast agent: T 1-shortening gadolinium chelate-containing liposomes and T2(*)-shortening micron-sized iron oxide particles (MPIO). Binding efficacy and MRI contrast effects were tested in cell cultures and a mouse stroke model. Both ICAM-1-targeted agents bound effectively to activated cerebrovascular cells in vitro, generating significant MRI contrast-enhancing effects. Direct in vivo MRI-based detection after stroke was only achieved with ICAM-1-targeted MPIO, although both contrast agents showed similar target-specific vascular accumulation. Our study demonstrates the potential of in vivo MRI of post-stroke ICAM-1 upregulation and signifies target-specific MPIO as most suitable contrast agent for molecular MRI of cerebrovascular inflammatio

Long-term cell survival and treatment outcome.

<p>A) Survival curves of mice with myocardial infarction transplanted with eCMs (n = 17), SMs (n = 14) and MSCs (n = 16), followed 7 weeks postoperatively. B) In vivo longitudinal BLI of representative mice at 5, 13 and 49 days after transplantation of eCMs (top) SMs (middle) and MSCs (bottom) to monitor long-term cell survival in infarcted myocardium. C) Longitudinal evaluation of heart function with echocardiography at day 5 and 49 after transplantation of eCMs, SMs and MSCs.</p

Quantification of cardiac function by MRI.

<p>Representative in vivo end-diastolic MR-images two weeks after myocardial infarction in A) short-axis (mid-LV) and B) long-axis orientation for each experimental group. Global cardiac morphology and function were obtained from in vivo cine MR-images: C) EDV, D) ESV, E) EF and F) CO. No MI: n = 6, MI+eCM: n = 5, MI+SM: n = 7, MI+MSC: n = 7 and MI: n = 8. *  =  p<0.05 vs. MI, †  =  p<0.05 vs. MI+eCM.</p

Assessment of regional contractile function by MRI.

<p>Regional contractile function two weeks after myocardial infarction, described by group-averaged A) end-systolic wall thickness and B) wall thickening after segmentation of the LV according to the 16 segment AHA model for mice with no MI (n = 6), MI+eCM (n = 5), MI+SM (n = 7), MI+MSC (n = 7) and MI (n = 8). *  =  p<0.05 vs. MI, †  =  p<0.1 vs. MI. The segment numbering is clarified in A).</p