The survey eAppendix was developed by an expert panel and implemented using SurveyMonkey software.
Sampling was based on proportional representation by state, and where groups of physicians reported the same zip code, city, or institution or practice, they were coded as a block, of which only 1 was available for sampling. Of approximately ASNC members, were selected to receive the survey. Nonrespondents received up to 3 follow-up requests, conducted by staff trained in performing scripted interviews.
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Categorical variables were compared using the Fisher exact test. Protocol volumes were estimated multiplying total laboratory volume by percentage of studies performed using a given protocol. Low-, medium-, and high-volume sites were defined based on tertile of annual procedure volumes. A total of 73 survey responses The median annual number of NSTs performed for the 59 respondents reporting nonzero volume was intertertile range, Forty-five respondents reported both laboratory volume and percentage of studies performed using each imaging protocol.
Low-dose stress-first imaging constituted only 7. Twenty-four of 48 respondents answering reported that their practice uses AUC to track appropriate use. Of the 73 individuals completing the survey, 36 responded to the question asking how many posteroanterior chest x-ray examinations would be equivalent to a single-day, rest-stress Tcm nuclear stress test.
We considered a range of to x-ray examinations ie, mSv, assuming the standard estimate of 0. Of these 36 respondents, 25 underestimated the dose. Twenty-two physicians omitted answering this question; among the 24 physicians responding, answers ranged from 1 to x-ray examinations. Over the past decade, important advances in nuclear cardiology have allowed for high-quality studies at substantially reduced radiation exposure.
This survey provides initial data describing current US NST practices, identifying that dose-reduction approaches have largely not been assimilated into everyday practice. The Very few sites used scanner hardware such as cameras using multiple solid-state detectors or improved image reconstruction software to reduce radiation doses. Our study has several limitations. Most significant is its modest sample size. While the response rate was similar to other recent practice-based surveys, 11 it is uncertain what differences exist between respondents and nonrespondents.
Not all respondents answered every question, although it is reasonable to expect those omitting a question are more likely to have suboptimal practices than those answering, suggesting that our data may reflect a bias toward underestimating actual underutilization of radiation protection approaches. Another limitation is that our findings are not based on data collected of actual protocols used and activities millicuries administered, but rather respondents' estimates and recall.
These may be subject to bias, as illustrated by the observed discordance between actual vs professed use of stress-only imaging.
New Developments in Nuclear Cardiac Imaging
Nevertheless, our findings suggest significant opportunities for improving radiation safety for the 10 million US patients undergoing NSTs annually. Specific goals should include the following: 1 bridging gaps between physicians' exposure to radiation safety literature and actual knowledge; 2 increasing use of low-dose stress-first imaging, while decreasing dual-isotope imaging; 3 promoting wider integration of AUC into clinical practice, and 4 fostering validation, use, and affordability of advanced technologies permitting reduced administered activity.
Thus, contemporary US nuclear cardiology practice is characterized by underuse of existing approaches to ensure justification and optimization of ionizing radiation use and by gaps in practitioners' knowledge pertaining to radiation safety. Targeted educational programs are needed to better disseminate patient-centered radiation safety practices and effectively incorporate these principles into clinical practice. Author Contributions: Drs Einstein and Shaw had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Abstract Considering the numerous, rapidly occurring advances in this field over the past 5 years, this monograph accomplishes the noteworthy goal of providing a fairly current presentation of the state of the art of several cardiac procedures gaining widespread acceptance in clinical practice. The editors deserve. Citations Citation. Published: Ann Intern Med. DOI: Sign in below to access your subscription for full content. Buy This Article Subscribe.
You will be redirected to acponline. Create Your Free Account Why? This approach is effective in terms of radiation dose reduction and should be considered as a standard practice with retrospectively gated spiral CT protocols. In patients with stable and low heart rates usually below 65 b.
The advantage of the axial scan protocol is that exposure only occurs during the phase that is intended for reconstruction, minimizing the overall radiation exposure. Also the z -axis oversampling is less using axial scan protocols. The drawback is that it relies on a regular and relatively low heart rate.
Depending on the system, no alternative cardiac phases may be available in the case of suboptimal image quality. An additional strategy to reduce the radiation exposure is based on reduction of scan time. Wide detector array scanners — rows and second- and third-generation dual-source CT scanners with high-pitch spiral scan protocols allow for complete coverage of the heart in a single gantry rotation. Radiation exposure is very low due to the lack of oversampling.
The prospectively ECG-triggered high-pitch spiral protocol on dual-source scanners results in substantially lower doses but requires a slow and regular heart rhythm. Finally, if the lowering of tube voltage is a very effective radiation dose-saving strategy in CCTA due to the correlation between effective dose and the square of tube voltage, this is not possible for calcium score. Indeed, the change of scan parameter can influence the CAC value, and therefore, in this setting, only tube current optimization can be performed.
Nuclear cardiology:principles and methods
The key points include main steps to set-up a CT protocol to minimize the radiation exposure. Even if large trials have yet to be conducted, it seems reasonable to address to hybrid imaging studies for those patients in whom perfusion defect allocation and assessment of the haemodynamic significance of individual lesions will play a determining role for further treatment and particularly for guiding revascularization procedures.
Nuclear and CT imaging are included in the management flow charts of patients with different cardiovascular diseases providing unique or alternative information when compared with other imaging modalities. Current international guidelines and recommendations include nuclear cardiology techniques and cardiac CT as appropriate modalities for different clinical scenarios see Supplementary material online , S1. Nevertheless, selection of functional cardiovascular imaging by nuclear modalities and anatomical imaging by CT depends on multiple factors including the clinical question, the age of the patient, the estimated pre-test probability of the disease, costs, availability and local expertise for each imaging technology, physician preferences, and patient convenience.
However, it should also be considered that imaging tests may carry risks not only related with radiations such as those associated with stressors, contrast agents, or other energy sources. For example, the induction of DNA double-strand breaks has been described after exposure to non-ionizing radiation from cardiac MR scanning 65 , 66 even if its impact on long-term risk is not clear and has not yet been sufficiently explored. The knowledge of all advantages and pitfalls for each imaging technique should be well known to select the best one for each patient.
A brief description of the role of nuclear diagnostic imaging in several clinical scenarios, as indicated in the current ESC guidelines and recommendations, is summarized in Supplementary material online , S1. Total expenditures related to advanced imaging show an increasing trend in Europe, raising concerns among health care providers.
Although most of the publications using non-invasive testing indicate cost-effectiveness over strategies without non-invasive tests, the overall published data are conflicting, particularly regarding the question which non-invasive strategy is the most cost-effective. Moreover, the definition of effectiveness often includes diagnostic accuracy or downstream utilization of resources and rarely more relevant endpoints such as efficacy on clinical outcome.
There are no studies available on the cost-effectiveness of radiation dose reduction strategies.
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Due to the present uncertainty of the risks associated with low radiation doses, the results of long follow-up studies assessing the impact on health and related costs are essential. However, lower dosages of the specific and most often expensive radiopharmaceuticals will most likely result in lower costs even if this assumption is dependent on local and national differences. In contrast with nuclear cardiology procedures, it is more difficult to predict the effects on costs in relation to a reduction in radiation dose with CT-driven protocols.
The increasing awareness of procedure-associated radiation has triggered the introduction of novel imaging protocols, and the development of new imaging technologies aiming at lowering radiation dose with further optimization of image quality.
The state-of-the-art nuclear cardiology and cardiac CT imaging require embracing best practices for appropriate patient selection, patient-centred imaging protocols, use of novel protocols for traditional scanners, and adoption of laboratory practices to reduce lifetime radiation exposure for patients and staff members. Supplementary material is available at European Heart Journal online. All the authors would like to thank Rozemarijn Vliegenthart for her substantial help in the revision of the manuscript.
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Table of contents. State-of-the-art technologies and their impact on radiation dose. Changed protocols, which have impact on dosimetry and patients. Appropriate clinical use of non-invasive cardiac imaging for reducing global radiation exposure.