Coronary calcium scan acquisition before coronary CT angiography: limited benefit or useful addition?

OBJECTIVE: This article reviews the role of coronary calcium quantification in symptomatic patients and the pros and cons of acquiring an unenhanced coronary calcium scan in every patient with suspected coronary artery disease referred for coronary CT angiography. CONCLUSION: The acquisition of a coronary calcium scan in every symptomatic patient referred for coronary CT angiography requires a case-by-case approach.

Advanced adaptive axial-sequential prospectively electrocardiogram-triggered dual-source coronary computed tomographic angiography in a patient with atrial fibrillation.

Atrial fibrillation is considered a relative contraindication to coronary computed tomographic angiography (CCTA) because image quality and radiation dose-saving measures largely depend on low and stable heart rates. Most published experiences with CCTA during atrial fibrillation have relied on retrospective gating to mitigate artifacts via electrocardiogram editing. However, a large number of patients arrive at the CT suite with irregular heart rates. We present a case in which we used a prospectively electrocardiogram-triggered axial-sequential scan mode with a novel arrhythmia protection algorithm to obtain motion-free, high-quality CCTA images at a low radiation dose.

Evaluating the performance of the Global Registry of Acute Coronary Events risk-adjustment index across socioeconomic strata among patients discharged from the hospital after acute myocardial infarction.

BACKGROUND: Cardiac risk-adjustment indices for acute coronary syndromes have important clinical and research applications, especially if proven to be valid and robust across heterogeneous socioeconomically diverse populations. The objective of this study was to validate the Global Registry of Acute Coronary Events (GRACE) risk-adjustment index for 6-month all-cause mortality across socioeconomic strata. METHODS: The study cohort consisted of patients who were enrolled in the SESAMI study and discharged alive from the hospital between December 1, 1999, and February 28, 2003. Socioeconomic information was obtained through self-report. Hospital chart abstraction was used to ascertain clinical detail required for the derivation of the GRACE risk index. Six-month mortality rates were obtained through data linkage using encrypted health card numbers. The accuracy (c-statistic) and calibration (Hosmer-Lemeshow) characteristics of the GRACE risk index were generated using logistic regression across income and education strata. RESULTS: Predicted and observed mortality rates were significantly higher among patients of lower incomes and education (ie, observed 6-month mortality: 5.1% vs 1.8% among low income vs high income patients, respectively, P < .0001; 4.6% vs 2.9% among low-educated vs highly educated patients, respectively, P = .02). The predicted 6-month mortality as derived using GRACE closely mirrored observed mortality rates with strong accuracy and precision (c-statistic = 0.80 for the overall cohort and within each income and education strata; Hosmer-Lemeshow goodness-of-fit test was not significant within each income and education strata). CONCLUSION: The GRACE risk score for 6-month all-cause mortality is an accurate, well-calibrated, and robust predictor across socioeconomic strata and can be used as a valid risk-adjustment index when examining socioeconomic-mortality differences after acute MI.

Dissecting the kinetics of the NADP(+)-FADH2 charge transfer complex and flavin semiquinones in neuronal nitric oxide synthase.

Electron flow within the neuronal nitric oxide synthase reductase domain (nNOSrd) includes hydride transfer from NADPH to FAD followed by two one-electron transfer reactions from FAD to FMN. We have used stopped flow spectrometry to closely monitor these electron transfer steps for both the wild type and the ΔG810 mutant of nNOSrd using a protocol involving both global analyses of the photodiode array spectral scans and curve fittings of single wavelength kinetic traces. The charge transfer complex and interflavin electron transfer events recorded at 750nm and 600nm, respectively, show the kinetics in different time frames. All electron transfer events are slow enough at 4°C to enable measurements of rate constants even for the fast charge transfer event. To our knowledge this is the first time the rate constants for the charge transfer between NADP(+) and FADH2 have been determined for NOS. These procedures allow us to conclude that (1) binding of the second NADPH is necessary to drive the full reduction of FMN and; (2) charge transfer and the subsequent interflavin electron transfer have distinct spectral features that can be monitored separately with stopped flow spectroscopy. These studies also enable us to conclude that interflavin electron transfer reported at 600nm is not limiting in NOS catalysis.

Clinical experiences of delayed contrast enhancement with cardiac computed tomography: case series.

BACKGROUND: Myocardial delayed enhancement (MDE) by gadolinium-enhanced cardiac MRI is well established for myocardial scar assessment in ischemic and non-ischemic heart disease. The role of MDE by cardiac CT (CT-MDE) is not yet defined. FINDINGS: We reviewed all clinical cases of CT-MDE at a tertiary referral center to present the cases as a case series. All clinical cardiac CT exams which utilized CT-MDE imaging between January 1, 2005 and October 1, 2010 were collected as a series and their findings were also compared with available myocardial imaging to assess for myocardial abnormalities, including echocardiography (wall motion, morphology), cardiac MRI (delayed enhancement, morphology), SPECT MPI (perfusion defects). 5,860 clinical cardiac CT exams were performed during the study period. CT-MDE was obtained in 18 patients and was reported to be present in 9 patients. The indications for CT-MDE included ischemic and non-ischemic heart diseases. In segments positive for CT-MDE, there was excellent agreement of CT with other modalities: echocardiography (n=8) demonstrated abnormal morphology and wall motion (k=1.0 and k=0.82 respectively); prior MRI (n=2) demonstrated abnormal delayed enhancement (MR-MDE) (k=1.0); SPECT MPI (n=1) demonstrated fixed perfusion defects (k=1.0). In the subset of patients without CT-MDE, no abnormal segments were identified by echocardiography (n=8), MRI (n=1) and nuclear MPI (n=0). CONCLUSIONS: CT-MDE was performed in rare clinical situations. The indications included both ischemic and non-ischemic heart disease and there was an excellent agreement between CT-MDE and abnormal myocardium by echocardiography, cardiac MRI, and nuclear MPI.

Paradoxical air embolism following contrast material injection through power injectors in patients with a patent foramen ovale.

In patients with a patent foramen ovale, use of air filters during intravenous infusions is common, but they are not compatible with power injection. Therefore we aimed to assess the incidence of paradoxical air embolism on CT of the chest and brain following contrast material injection through a power injector in patients with a patent foramen ovale, without the use of a filter. In this IRB approved, HIPAA compliant retrospective study, two independent radiologists reviewed 289 CT scans of the chest (n = 233) and brain (n = 56) for vascular air embolism following contrast material injection through a power injector in 93 subjects (43 men, mean age 66 y) with a known patent foramen ovale. The location and amount of the air were assessed. The medical records were reviewed for embolic symptoms. The prevalence and location of right sided and systemic luminal air were determined and inter-observer agreement for detection of intraluminal vascular air was calculated. Vascular air embolism was observed in 19.3% (56/289) of the studies; small in 52 and moderate in 4. In 42 studies, intravascular air was seen in a single territory and 14 studies had intravascular air in multiple territories. None had air in the left side of the heart or brain to suggest paradoxical air embolism. The inter-observer agreement for detection of vascular air was moderate (k = 0.6). Paradoxical air embolism in patients with a patent foramen ovale following contrast material injection with a power injector is rare.

ACR Appropriateness Criteria(®) acute nonspecific chest pain-low probability of coronary artery disease.

This document outlines the usefulness of available diagnostic imaging for patients without known coronary artery disease and at low probability for having coronary artery disease who do not present with classic signs, symptoms, or electrocardiographic abnormalities indicating acute coronary syndrome but rather with nonspecific chest pain leading to a differential diagnosis, including pulmonary, gastrointestinal, or musculoskeletal pathologies. A number of imaging modalities are available to evaluate the broad spectrum of possible pathologies in these patients, such as chest radiography, multidetector CT, MRI, ventilation-perfusion scans, cardiac perfusion scintigraphy, transesophageal and transthoracic echocardiography, PET, spine and rib radiography, barium esophageal and upper gastrointestinal studies, and abdominal ultrasound. It is considered appropriate to start the assessment of these patients with a low-cost, low-risk diagnostic test such as a chest x-ray. Contrast-enhanced gated cardiac and ungated thoracic multidetector CT as well as transthoracic echocardiography are also usually considered as appropriate in the evaluation of these patients as a second step if necessary. A number of rest and stress single-photon emission CT myocardial perfusion imaging, ventilation-perfusion scanning, aortic and chest MR angiographic, and more specific x-ray and abdominal examinations may be appropriate as a third layer of testing, whereas MRI of the heart or coronary arteries and invasive testing such as transesophageal echocardiography or selective coronary angiography are not considered appropriate in these patients. Given the low risk of these patients, it is mandated to minimize radiation exposure as much as possible using advanced and appropriate testing protocols. The ACR Appropriateness Criteria® are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Normal magnetic resonance imaging of the thorax.

The soft tissue contrast properties of magnetic resonance (MR) allow excellent discrimination of most intrathoracic structures other than the lungs, and allow good insight into normal anatomy. Using MR imaging, the normal cardiorespiratory system, including portions of the lungs and pleural spaces, as well as the mediastinal, chest wall, and cardiac structures can be well depicted. In addition, using newer MR pulse sequences, dynamic ECG-gated imaging can also be achieved, which allows a window into the normal functional processes of these organs.

Extracardiac findings in cardiac computed tomographic angiography in patients at low to intermediate risk for coronary artery disease.

PURPOSE: To evaluate the prevalence, clinical significance, interobserver agreement, and follow-up of extracardiac findings on coronary computed tomographic angiography (CTA). METHODS: A prospectively recruited cohort of 80 patients at low to intermediate risk of having coronary artery disease underwent CTA with field of view imaging from lung apices to upper abdomen. Two staff radiologists read each scan independently. Scans read by reader no. 1 were read as part of routine clinical practice, and the findings were subsequently reclassified to potentially significant, as defined by requiring clinical or radiologic follow-up, and insignificant by a separate observer, whereas reader no. 2 retrospectively read and autonomously classified the findings as potentially significant or insignificant. RESULTS: Reader no. 1 found 7 potentially significant findings in 7 patients and 33 insignificant findings in 29 patients. Reader no. 2 found 10 potentially significant findings in 10 patients and 59 insignificant findings in 42 patients. Inter-rater agreement was moderate (kappa = 0.49; 95% confidence interval, 0.31-0.67) for the presence vs the absence of extracardiac findings and moderate (kappa = 0.52; 95% confidence interval, 0.15-0.89) for the presence of potentially significant extracardiac findings. The most common potentially significant finding was possibly malignant lung nodule (n = 6 [reader 1], 4 [reader 2]). Four patients with potentially significant findings received follow-up imaging, and 1 patient underwent biopsy, which was complicated by pneumothorax. No diagnoses of malignancy were made. CONCLUSIONS: Extracardiac findings are frequent and moderately reproducible, however, in this study, not associated with clinical benefit. Large prospective studies are required to establish whether reporting of extracardiac findings is associated with improved patient outcomes.

Iroquois genes influence proximo-distal morphogenesis during rat lung development.

Lung development is a highly regulated process directed by mesenchymal-epithelial interactions, which coordinate the temporal and spatial expression of multiple regulatory factors required for proper lung formation. The Iroquois homeobox (Irx) genes have been implicated in the patterning and specification of several Drosophila and vertebrate organs, including the heart. Herein, we investigated whether the Irx genes play a role in lung morphogenesis. We found that Irx1-3 and Irx5 expression was confined to the branching lung epithelium, whereas Irx4 was not expressed in the developing lung. Antisense knockdown of all pulmonary Irx genes together dramatically decreased distal branching morphogenesis and increased distention of the proximal tubules in vitro, which was accompanied by a reduction in surfactant protein C-positive epithelial cells and an increase in beta-tubulin IV and Clara cell secretory protein positive epithelial structures. Transmission electron microscopy confirmed the proximal phenotype of the epithelial structures. Furthermore, antisense Irx knockdown resulted in loss of lung mesenchyme and abnormal smooth muscle cell formation. Expression of fibroblast growth factors (FGF) 1, 7, and 10, FGF receptor 2, bone morphogenetic protein 4, and Sonic hedgehog (Shh) were not altered in lung explants treated with antisense Irx oligonucleotides. All four Irx genes were expressed in Shh- and Gli(2)-deficient murine lungs. Collectively, these results suggest that Irx genes are involved in the regulation of proximo-distal morphogenesis of the developing lung but are likely not linked to the FGF, BMP, or Shh signaling pathways.

Major trauma in pregnant women during the summer.

BACKGROUND: Pregnant women represent a major challenge in trauma care because of the risks to both mother and child and because of the difficulties in following standard protocols. METHODS: We analyzed data for all pregnant women admitted to the hospital in Canada over 7 years to test whether major trauma still clustered in the summer despite their aversion toward alcohol, recklessness, and extreme sports. RESULTS: A total of 2,618 pregnant women sustained major trauma. The prevalence of pregnancy was marginally lower in summer than in winter (decrease, 3%; 95% confidence interval, 2-4%), whereas the incidence of major trauma in pregnant women was significantly higher in summer than in winter (increase, 12%; 95% confidence interval, 3-21%; p = 0.005). No evidence of offsetting decreases in severity appeared in analyses of length of stay, number of surgical procedures, or mortality. CONCLUSION: We suggest that normal lifestyle choices contribute to an increased risk of major trauma during pregnancy and merit greater awareness throughout the year.