Maternal and Fetal Radiation-Induced Cancer Risk From Computed Tomography Pulmonary Angiography During Pregnancy: A Retrospective Cohort Study Across a Multihospital Integrated Health Care Network.

OBJECTIVE: Computed tomography pulmonary angiogram (CTPA) is important to evaluate suspected pulmonary embolism in pregnancy but has maternal/fetal radiation risks. The objective of this study was to estimate maternal and fetal radiation-induced cancer risk from CTPA during pregnancy. METHODS: Simulation modeling via the National Cancer Institute's Radiation Risk Assessment Tool was used to estimate excess cancer risks from 17 organ doses from CTPA during pregnancy, with doses determined by a radiation dose indexing monitoring system. Organ doses were obtained from a radiation dose indexing monitoring system. Maternal and fetal cancer risks per 100,000 were calculated for male and female fetuses and several maternal ages. RESULTS: The 534 CTPA examinations had top 3 maternal organ doses to the breast, lung, and stomach of 17.34, 15.53, and 9.43 mSv, respectively, with a mean uterine dose of 0.21 mSv. The total maternal excess risks of developing cancer per 100,000 were 181, 151, 121, 107, 94.5, 84, and 74.4, respectively, for a 20-, 25-, 30-, 35-, 40-, 45-, and 50-year-old woman undergoing CTPA, compared with baseline cancer risks of 41,408 for 20-year-old patients. The total fetal excess risks of developing cancer per 100,000 were 12.3 and 7.3 for female and male fetuses, respectively, when compared with baseline cancer risks of 41,227 and 48,291. DISCUSSION: Excess risk of developing cancer from CTPA was small relative to baseline cancer risk for pregnant patients and fetuses, decreased for pregnant patients with increasing maternal age, and was greater for female fetuses than male fetuses.

Patient and Fetal Radiation-Induced Malignancy Risk From Imaging For Evaluation of Pulmonary Embolism in Pregnancy.

BACKGROUND: Imaging for diagnosis of suspected pulmonary embolism in pregnancy presents radiation concerns for patient and fetus. OBJECTIVES: Estimate the risks of radiation-induced breast cancer and childhood leukemia from common imaging techniques for the evaluation of suspected pulmonary embolism in pregnancy. METHODS: Breast and uterine absorbed doses for various imaging techniques were input into the National Cancer Institute Radiation Risk Assessment Tool to calculate risk of breast cancer for the patient and childhood leukemia for the fetus. Absorbed doses were obtained by synthesizing data from a recent systematic review and the International Commission on Radiological Protection. Primary outcomes were the estimated excess incidences of breast cancer and childhood leukemia per 100,000 exposures. RESULTS: Baseline incidences of breast cancer for a 30-year-old woman and childhood leukemia for a male fetus were 13,341 and 939, respectively. Excess incidences of breast cancer were 0.003 and 0.275 for a single and two-view chest radiograph, respectively, 9.53 and 20.6 for low- and full-dose computed tomography pulmonary angiography (CTPA), respectively, 0.616 and 2.54 for low- and full-dose perfusion scan, respectively, and 0.732 and 2.66 for low- and full-dose ventilation perfusion scan, respectively. Excess incidences of childhood leukemia were 0.004 and 0.007 for a single and two-view chest radiograph, respectively, 0.069 and 0.490 for low- and full-dose CTPA, respectively, 0.359 and 1.47 for low- and full-dose perfusion scan, respectively, and 0.856 and 1.97 for low- and full-dose ventilation perfusion scan, respectively. CONCLUSION: Excess cancer risks for all techniques were small relative to baseline cancer risks, with CTPA techniques carrying slightly higher risk of breast cancer for the patient and ventilation perfusion techniques a higher risk of childhood leukemia.

Cardiac MRI for Patients With Cardiac Implantable Electronic Devices.

OBJECTIVE. Patients with cardiac implantable electronic devices (CIEDs) require cardiac MRI (CMRI) for a variety of reasons. The purpose of this study is to review and evaluate the value and safety of CMRI for patients with in situ CIEDs. CONCLUSION. Late gadolinium enhancement CMRI is the reference standard for assessing myocardial viability in patients with ventricular tachycardia before ablation of arrhythmogenic substrates. The use of late gadolinium enhancement CMRI for patients with CIEDs is safe as long as an imaging protocol is in place and precaution measures are taken.

Impact of the revised haemodynamic definition on the diagnosis of pulmonary hypertension in patients with systemic sclerosis.

INTRODUCTION: Pulmonary arterial hypertension (PAH) is one of the leading causes of mortality in systemic sclerosis (SSc). We explored the impact of the updated haemodynamic definition of pulmonary hypertension (PH), as proposed by the 6th World Symposium on Pulmonary Hypertension. METHODS: In this single-centre retrospective analysis, patients with SSc who had right heart catheterisation (RHC) were included. We compared the prior PH definition to the updated PH definition. The prior definition classified PH as mean pulmonary arterial pressure (mPAP) ≥25 mmHg and further divided into pre-capillary PH (PAH and PH due to lung disease and/or hypoxia), post-capillary PH, and combined pre- and post-capillary PH groups. For the updated definition, PH was classified as mPAP >20 mmHg and further divided into the different groups. We validated our findings in the DETECT cohort. RESULTS: Between 2005 and March 2019, 268 RHCs were performed in this single-centre cohort. Using the prior definition, 137 (51%) were diagnosed with PH, with 89 classified as pre-capillary PH (56 with PAH and 33 with PH due to lung disease and/or hypoxia), 29 as post-capillary PH, and 19 as combined pre- and post-capillary PH. When the updated definition was applied to the cohort, seven out of 131 (5%) with no PH were reclassified to pre-capillary PH (PAH (n=1), PH due to lung disease (n=3) and post-capillary PH (n=3)). In those with mPAP 21-24 mmHg, with no left heart or significant lung disease, one out of 28 (4%) in our cohort and four out of 36 (11%) in the DETECT cohort were reclassified as PAH. CONCLUSION: The updated PH definition does not appear to have a significant impact on the diagnosis of PH in two different screening cohorts.

Best practices for MRI systematic reviews and meta-analyses.

As defined by the Cochrane Collaboration, a systematic review is a review of evidence with a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review. Meta-analysis is a statistical method to combine the results from primary studies that accounts for sample size and variability to provide a summary measure of the studied outcome. Systematic reviews of diagnostic test accuracy present unique methodological and reporting challenges not present in systematic reviews of interventions. This review provides guidance and further resources highlighting current best practices in methodology and reporting of systematic reviews of diagnostic test accuracy, with a specific focus on challenges and opportunities for MRI imaging. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

Interrater Agreement and Diagnostic Accuracy of a Novel Computer-Aided Detection Process for the Detection and Prevention of Retained Surgical Instruments.

OBJECTIVE: The purpose of this study is to evaluate the diagnostic accuracy of a process incorporating computer-aided detection (CAD) for the detection and prevention of retained surgical instruments using a novel nondeformable radiopaque µTag. MATERIALS AND METHODS: A high-specificity CAD system was developed iteratively from a training set (n = 540 radiographs) and a validation set (n = 560 radiographs). A novel test set composed of 700 thoracoabdominal radiographs (410 with a randomly placed µTag and 290 without a µTag) was obtained from 10 cadavers embedded with confounding iatrogenic objects. Data were analyzed first by the blinded CAD system; radiographs coded as negative (n = 373) were then independently reviewed by five blinded radiologists. The reference standard was the presence of a µTag. Sensitivity and specificity were calculated. Interrater agreement was assessed with Cohen kappa values. Mean (± SD) image analysis times were calculated. RESULTS: The high-specificity CAD system had one false-positive (sensitivity, 79.5% [326/410]; specificity, 99.7% [289/290]). A combination of the CAD system and one failsafe radiologist had superior sensitivity (98.5% [404/410] to 100% [410/410]) and specificity (99.0% [287/290] to 99.7% [289/290]), with 327 (47%) radiographs not requiring immediate radiologist review. Interrater agreement was almost perfect for all radiologist pairwise comparisons (κ = 0.921-0.992). Cumulative mean image analysis time was less than one minute (CAD, 29 ± 2 seconds; radiologists, 26 ± 16 seconds). CONCLUSION: The combination of a high-specificity CAD system with a failsafe radiologist had excellent diagnostic accuracy in the rapid detection of a nondeformable radiopaque µTag.

Practical Approaches to Quality Improvement for Radiologists.

Continuous quality improvement is a fundamental attribute of high-performing health care systems. Quality improvement is an essential component of health care, with the current emphasis on adding value. It is also a regulatory requirement, with reimbursements increasingly being linked to practice performance metrics. Practice quality improvement efforts must be demonstrated for credentialing purposes and for certification of radiologists in practice. Continuous quality improvement must occur for radiologists to remain competitive in an increasingly diverse health care market. This review provides an introduction to the main approaches available to undertake practice quality improvement, which will be useful for busy radiologists. Quality improvement plays multiple roles in radiology services, including ensuring and improving patient safety, providing a framework for implementing and improving processes to increase efficiency and reduce waste, analyzing and depicting performance data, monitoring performance and implementing change, enabling personnel assessment and development through continued education, and optimizing customer service and patient outcomes. The quality improvement approaches and underlying principles overlap, which is not surprising given that they all align with good patient care. The application of these principles to radiology practices not only benefits patients but also enhances practice performance through promotion of teamwork and achievement of goals.

How to perform a critical appraisal of diagnostic tests: 7 steps.

The critically appraised topic (CAT) is a format in evidence-based practice for sharing information. A CAT is a standardized way of summarizing the most current research evidence focused on a pertinent clinical question. Its aim is to provide both a critique of the most up-to-date retrieved research and an indication of the clinical relevance of results. A clinical question is initially generated following a patient encounter, which leads to and directs a literature search to answer the clinical question. Studies obtained from the literature search are assigned a level of evidence. This allows the most valid and relevant articles to be selected and to be critically appraised. The results are summarized, and this information is translated into clinically useful procedures and processes.

Ten-Year Trend in Advanced Imaging Utilization for Suspected Pulmonary Embolism in Pregnancy.

PURPOSE: Advanced imaging is essential to diagnose pulmonary embolism (PE) in pregnancy, but there are associated maternal and fetal radiation risks. The purpose of this study was to evaluate the 10-year trend in advanced imaging utilization for the evaluation of suspected PE in pregnancy. METHODS: The authors evaluated pregnant women with advanced imaging using CT pulmonary angiography (CTPA) or lung scintigraphy (LS) for evaluation of suspected PE presenting to two tertiary hospitals from 2007 to 2016. The rate of imaging was evaluated relative to positive PE rate and local pregnancy rate. positive PE was defined as a new acute PE finding on any advanced imaging within 3 days of first advanced imaging test. Local pregnancy rates were defined per 1,000 pregnancies in the county serviced by both hospitals. Chi-square testing was used to evaluate statistical significance (P < .05) in the utilization trend of advanced imaging and relative to local pregnancy rates and evaluations positive for PE. RESULTS: A total of 707 pregnant patients were identified, of whom 92.5% (n = 654) underwent CTPA and 7.5% (n = 53) underwent LS. Regression analysis showed an average increase of 5.2 advanced imaging studies per year (P < .001), with 61 and 105 studies performed in 2007 and 2016, respectively. Additionally, there was an average increase of 0.08 (P < .001) advanced imaging studies per 1,000 local pregnancies per year, doubling from 0.7 in 2007 to 1.4 in 2016 (P < .001). Finally, there was a decrease of 0.004 (P = .009) in advanced imaging positive for PE, from 3% (2 of 61) in 2007 to 0% (0 of 100) in 2016. CONCLUSIONS: Advanced imaging utilization increased by 72% over the 10-year window, driven by higher use of CTPA. Although the detection rate of PE on advanced imaging has decreased, the utilization rate among pregnant patients doubled during this period. These results highlight the need to consider the radiation risks and costs of advanced imaging in specific patient populations.

Asymmetric expansion of aortic aneurysms on computed tomography imaging.

OBJECTIVE: To investigate whether wall growth during aneurysm development spares the aortic wall between the intercostal or lumbar arteries or, alternatively, is uniform around the circumference. METHODS: Computed tomography scans of 155 patients with aortic aneurysms (40 thoracic, 50 thoracoabdominal, and 65 abdominal) in a single hospital of a large academic institution were retrospectively inspected. Computed tomography studies of 100 control subjects (40 thoracic and 60 abdominal) were also reviewed. In all 255 patients, the ratio of the arc length between the origins of the intercostal or lumbar arteries (interbranch arc length) to the remainder of the aortic residual circumference was calculated. These ratios were compared between all subjects with aneurysms and the controls at each vertebral body level and between those with thoracic or thoracoabdominal or abdominal aneurysms and controls at each vertebral body level. RESULTS: Interbranch arc lengths and residual aortic circumferences were larger in aneurysm patients than in control subjects, but the differences were statistically significant only at T4 and from T8 to L4 (P = .009 to P < .001) and from T4 to L4 (P < .001), respectively. The ratio of interbranch arc length to residual circumference in aneurysmal aortas was significantly smaller than that in controls at 12 out of 13 levels from T4 to L4 (P = .004 to P < .001). There was a statistically significant smaller ratio at 8 out of 9 levels for thoracic aneurysms (P = .006 to P < .001), 12 out of 13 levels for thoracoabdominal aneurysms (P = .008 to P < .001), and 3 out of 4 levels for abdominal aneurysms compared with controls (P = .006 to P < .001). CONCLUSIONS: Wall growth in aortic aneurysms is asymmetric, with greater aneurysmal growth in the anterior aorta wall and relative sparing of the portion of aortic wall between the intercostal or lumbar arteries. The mechanisms effecting this asymmetric growth have not been fully characterized.

Aortic branch artery pseudoaneurysms accompanying aortic dissection. Part III: natural history.

PURPOSE: To document the natural history of branch artery pseudoaneurysms (BAPs), which are sequelae of aortic dissection with false lumen thrombosis that have been distinguished anatomically from penetrating ulcers. MATERIALS AND METHODS: Serial computed tomography (CT) scans in 50 patients with at least two CT scans greater than 1 month apart were retrospectively studied. Mean follow-up was 29 months, with longitudinal analyses of 119 BAPs. Changes in BAPs, false lumen thrombosis, and aortic diameter were assessed. RESULTS: No patient had an aortic rupture or other poor outcome. All BAPs eventually disappeared (ie, thrombosed), with 50% thrombosed within 18 months. Aortas were ectatic, with a mean diameter of 36 mm. There was no statistically significant change in total aortic diameters; however, there was a significant increase in true lumen diameters (P < .0001) and a significant decrease in false lumen thickness (P < .0001) at the level of the BAP over time (mean 50% reduction in maximum thickness of thrombosed false lumen). There were no significant associations between BAP thrombosis and vertebral level, presence of more than one BAP, presence of branch artery in communication with the BAP, history of smoking, diabetes mellitus or hypertension, or treatment with ß-blockers, other antihypertensive medication, statins, or anticoagulation therapy. After controlling for other variables, BAPs were less likely to thrombose if an ulcerlike projection was present (P = .003), in men (P = .02), in subjects with hypertension (P = .04), and in older patients (P = .05). CONCLUSIONS: Most BAPs spontaneously thrombose, and associated intramural hematoma regresses/disappears. Isolated BAPs were not associated with poor clinical outcomes.

Comparison of Guidelines for Evaluation of Suspected Pulmonary Embolism in Pregnancy: A Cost-effectiveness Analysis.

BACKGROUND: Pulmonary embolism (PE) remains a leading cause of maternal mortality, yet diagnosis remains challenging. International diagnostic guidelines vary significantly in their recommendations, making it difficult to determine an optimal policy for evaluation. RESEARCH QUESTION: Which societal-level diagnostic guidelines for evaluation of suspected PE in pregnancy are an optimal policy in terms of its cost-effectiveness? STUDY DESIGN AND METHODS: We constructed a complex Markov decision model to evaluate the cost-effectiveness of each identified societal guidelines for diagnosis of PE in pregnancy. Our model accounted for risk stratification, empiric treatment, diagnostic testing strategies, as well as short- and long-term effects from PE, treatment with low-molecular-weight heparin, and radiation exposure from advanced imaging. We considered clinical and cost outcomes of each guideline from a US health care system perspective with a lifetime horizon. Clinical effectiveness and costs were measured in time-discounted quality-adjusted life years (QALYs) and US dollars, respectively. Strategies were compared using the incremental cost-effectiveness ratio (ICER) with a willingness-to-pay threshold of $100,000/QALY. One-way, multiway, and probabilistic sensitivity analyses were performed. RESULTS: We identified six international societal-level guidelines. Base-case analysis showed the guideline proposed by the American Thoracic Society and Society of Thoracic Radiology (ATS-STR) yielded the highest health benefits (22.90 QALYs) and was cost-effective, with an ICER of $7,808 over the guidelines proposed by the Australian Society of Thrombosis and Haemostasis and the Society of Obstetric Medicine of Australia and New Zealand (ASTH-SOMANZ). All remaining guidelines were dominated. The ATS-STR guideline-recommended strategy yielded an expected additional 2.7 QALYs/100 patients evaluated over the ASTH-SOMANZ. Conclusions were robust to sensitivity analyses, with the ATS-STR guidelines optimal in 86% of probabilistic sensitivity analysis scenarios. INTERPRETATION: The ATS-STR guidelines for diagnosis of suspected PE in pregnancy are cost-effective and generate better expected health outcomes than guidelines proposed by other medical societies.

How to perform a critically appraised topic: part 1, ask, search, and apply.

OBJECTIVE: This article outlines the first three steps involved in performing a critically appraised topic for studies of diagnostic tests: Ask, formulate a question; Search, search the literature; and Apply, apply a level of evidence to the retrieved literature. CONCLUSION: Critically appraised topics provide a structured approach to formulating a clinical question, effectively searching the literature, assigning a level of evidence to the obtained literature, appraising the literature, and making recommendations for clinical practice.

How to perform a critically appraised topic: part 2, appraise, evaluate, generate, and recommend.

OBJECTIVE: This article continues the discussion of a critically appraised topic started in Part 1. A critically appraised topic is a practical tool for learning and applying critical appraisal skills. This article outlines steps 4-7 involved in performing a critically appraised topic for studies of diagnostic tests: Appraise, Appraise the literature; Evaluate, evaluate the strength of the evidence from the literature; Generate, generate graphs of conditional probability; and Recommend, draw conclusions and make recommendations. CONCLUSION: For steps 4-7 of performing a critically appraised topic, the main study results are summarized and translated into clinically useful measures of accuracy, efficacy, or risk.

Challenges, controversies, and hot topics in pulmonary embolism imaging.

OBJECTIVE: The purpose of this article is to discuss the diagnostic role of pulmonary CT angiography (CTA) in the workup of pulmonary embolism (PE), including specific populations, and issues such as pulmonary CTA combined with indirect CT venography; radiation dose considerations; the management of isolated subsegmental PE; and new technologic developments, such as dual-source/dual-energy pulmonary CTA. CONCLUSION: The role of pulmonary CTA will continue to grow with the emergence of MDCT and dual-energy CT and their improved capabilities. However, the need for any given CT examination should always be justified on the basis of the individual patient's benefits and risks.

Reference normal absolute and indexed values from ECG-gated MDCT: left atrial volume, function, and diameter.

OBJECTIVE: The purpose of this study was to retrospectively determine CT-based normal reference values of left atrial volume, function, and diameter normalized by age, sex, and body surface area. MATERIALS AND METHODS: The study group consisted of 74 subjects with normal findings at ECG-gated coronary CT angiography performed with retrospective gating. Analysis of left atrial volume (end-diastolic, end-systolic, and stroke volume) and function (ejection fraction) was performed with the Simpson method. Left atrial diameter was measured in the anteroposterior dimension. General linear model analysis was performed to model the data and assess statistical significance by age group after adjustment for sex and body surface area. RESULTS: The reference range for left atrial volume, function, and diameter was normalized (indexed) to age, sex, and body surface area in healthy subjects. A statistically significant difference was noted between left atrial volume and age without adjustment for sex and body surface area, but no statistically significant difference was found after adjustment for these variables. Sex and body surface area had a significant influence on left atrial volume, function, and diameter. CONCLUSION: Left atrial volume, function, and diameter normalized to age, sex, and body surface area can be reported from CTA datasets and may provide information important for patient care.

CT pulmonary angiography in pregnancy: Specific conversion factors to estimate effective radiation dose from dose length product: A retrospective cross-sectional study across a multi-hospital integrated healthcare network.

PURPOSE: Effective dose describes radiation-related cancer risk from CT scans and is estimated using a readily available conversion factor (k-factor), which varies by body part and study type. To purpose of this study is to determine the specific k-factor for CTPA in pregnant patients and its predictive factors. METHODS: This retrospective cross-sectional study evaluates CTPA in pregnancy across a multihospital integrated healthcare network from January 2012 to April 2017. Patient and CTPA-related data were obtained from the electronic health record and a radiation dose index monitoring system. Each patient's effective dose was determined by patient-specific Monte-Carlo simulation with Cristy phantoms and divided by patient dose-length-product to determine the k-factor. K-factor for pregnant patients was compared to the k-factor for adults of standard physique with a one-sample t-test. Bivariate and multivariable analyses were performed for patient and CT predictors of k-factor. RESULTS: A total of 534 patients were included. The mean k-factor for all patients was 0.0249 (mSv·mGy-1·cm-1), 78% greater than k-factor of 0.014 (p < 0.001) suggested for the general adult population. Multivariable analysis demonstrated lower k-factors with increasing pitch (p = 0.0002), patient size (p < 0.001), and scan length (p < 0.0001). The 120 kVp (p < 0.001) and 140 kVp (p = 0.0028) analyses showed a larger k-factor than 80 and 100 kVp studies combined. CONCLUSIONS: Specific k-factor for CTPA in pregnant patients is greater than the previously used generic chest CT k-factor and should be used to estimate the effective dose for CTPA exams in pregnancy.

Interstitial lung disease in systemic sclerosis quantification of disease classification and progression with high-resolution computed tomography: An observational study.

Introduction: Systemic sclerosis-associated interstitial lung disease accounts for up to 20% of mortality in these patients and has a highly variable prognosis. Functional respiratory imaging, a quantitative computed tomography imaging technique which allows mapping of regional information, can provide a detailed view of lung structures. It thereby shows potential to better characterize this disease. Purpose: To evaluate the use of functional respiratory imaging quantitative computed tomography in systemic sclerosis-associated interstitial lung disease staging, as well as the relationship between short-term changes in pulmonary function tests and functional respiratory imaging quantitative computed tomography with respect to disease severity. Materials and methods: An observational cohort of 35 patients with systemic sclerosis was retrospectively studied by comparing serial pulmonary function tests and in- and expiratory high-resolution computed tomography over 1.5-year interval. After classification into moderate to severe lung disease and limited lung disease (using a hybrid method integrating quantitative computed tomography and pulmonary function tests), post hoc analysis was performed using mixed-effects models and estimated marginal means in terms of functional respiratory imaging parameters. Results: At follow-up, relative mean forced vital capacity percentage change was not significantly different in the limited (6.37%; N = 13; p = 0.053) and moderate to severe disease (-3.54%; N = 16; p = 0.102) groups, respectively. Specific airway resistance decreased from baseline for both groups. (Least square mean changes -25.11% predicted (p = 0.006) and -14.02% predicted (p = 0.001) for limited and moderate to severe diseases.) In contrast to limited disease from baseline, specific airway radius increased in moderate to severe disease by 8.57% predicted (p = 0.011) with decline of lower lobe volumes of 2.97% predicted (p = 0.031). Conclusion: Functional respiratory imaging is able to differentiate moderate to severe disease versus limited disease and to detect disease progression in systemic sclerosis.

Meta-analysis: effectiveness of drugs for preventing contrast-induced nephropathy.

BACKGROUND: N-Acetylcysteine, theophylline, and other agents have shown inconsistent results in reducing contrast-induced nephropathy. PURPOSE: To determine the effect of these agents on preventing nephropathy. DATA SOURCES: Relevant randomized, controlled trials were identified by computerized searches in MEDLINE (from 1966 through 3 November 2006), EMBASE (1980 through November 2006), PubMed, Web of Knowledge (Current Contents Connect, Web of Science, BIOSIS Previews, and ISI Proceedings for the latest 5 years), and the Cochrane Library databases (up to November 2006). Databases were searched for studies in English, Spanish, French, Italian, and German. STUDY SELECTION: Randomized, controlled trials that administered N-acetylcysteine, theophylline, fenoldopam, dopamine, iloprost, statin, furosemide, or mannitol to a treatment group; used intravenous iodinated contrast; defined contrast-induced nephropathy explicitly; and reported sufficient data to construct a 2 x 2 table of the primary effect measure. DATA EXTRACTION: Abstracted information included patient characteristics, type of contrast media and dose, periprocedural hydration, definition of contrast-induced nephropathy, and prophylactic agent dose and route. DATA SYNTHESIS: In the 41 studies included, N-acetylcysteine (relative risk, 0.62 [95% CI, 0.44 to 0.88]) and theophylline (relative risk, 0.49 [CI, 0.23 to 1.06]) reduced the risk for contrast-induced nephropathy more than saline alone, whereas furosemide increased it (relative risk, 3.27 [CI, 1.48 to 7.26]). The remaining agents did not significantly affect risk. Significant subgroup heterogeneity was present only for N-acetylcysteine. No publication bias was discerned. LIMITATIONS: All trials evaluated the surrogate end point of contrast-induced nephropathy as the primary outcome. The lack of a statistically significant renoprotective effect of theophylline may result from insufficient data or study heterogeneity. True study quality remains uncertain. CONCLUSION: N-acetylcysteine is more renoprotective than hydration alone. Theophylline may also reduce risk for contrast-induced nephropathy, although the detected association was not significant. Our data support the administration of N-acetylcysteine prophylaxis, particularly in high-risk patients, given its low cost, availability, and few side effects.

Significant incidental cardiac disease on thoracic CT: what the general radiologist needs to know.

OBJECTIVE: Incidental cardiac findings are often found on chest CT studies, some of which may be clinically significant. The objective of this pictorial review is to illustrate and describe the appearances and management of the most frequently encountered significant cardiac findings on non-electrocardiographically gated thoracic CT. Most radiologists will interpret multidetector chest CT and should be aware of the imaging appearances, significance, and the appropriate next management steps, when incidental significant cardiac disease is encountered on thoracic CT. CONCLUSION: This article reviews significant incidental cardiac findings which may be encountered on chest CT studies. After completing this review, the reader should not only be familiar with recognizing clinically significant cardiac findings seen on thoracic CT examinations but also have the confidence to direct their further management.