Effects of radiation exposure from cardiac imaging: how good are the data?

DuDoCFNet: Dual-Domain Coarse-to-Fine Progressive Network for Simultaneous Denoising, Limited-View Reconstruction, and Attenuation Correction of Cardiac SPECT

Single-Photon Emission Computed Tomography (SPECT) is widely applied for the diagnosis of coronary artery diseases. Low-dose (LD) SPECT aims to minimize radiation exposure but leads to increased image noise. Limited-view (LV) SPECT, such as the latest GE MyoSPECT ES system, enables accelerated scanning and reduces hardware expenses but degrades reconstruction accuracy. Additionally, Computed Tomography (CT) is commonly used to derive attenuation maps ( μ -maps) for attenuation correction (AC) of cardiac SPECT, but it will introduce additional radiation exposure and SPECT-CT misalignments. Although various methods have been developed to solely focus on LD denoising, LV reconstruction, or CT-free AC in SPECT, the solution for simultaneously addressing these tasks remains challenging and under-explored. Furthermore, it is essential to explore the potential of fusing cross-domain and cross-modality information across these interrelated tasks to further enhance the accuracy of each task. Thus, we propose a Dual-Domain Coarse-to-Fine Progressive Network (DuDoCFNet), a multi-task learning method for simultaneous LD denoising, LV reconstruction, and CT-free μ -map generation of cardiac SPECT. Paired dual-domain networks in DuDoCFNet are cascaded using a multi-layer fusion mechanism for cross-domain and cross-modality feature fusion. Two-stage progressive learning strategies are applied in both projection and image domains to achieve coarse-to-fine estimations of SPECT projections and CT-derived μ -maps. Our experiments demonstrate DuDoCFNet's superior accuracy in estimating projections, generating μ -maps, and AC reconstructions compared to existing single- or multi-task learning methods, under various iterations and LD levels. The source code of this work is available at https://github.com/XiongchaoChen/DuDoCFNet-MultiTask.

National cost savings, operational and safety benefits from use of magnetocardiography in the assessment of emergency department chest pain patients

Study objectives

Patients frequently present to the emergency department (ED) with chest pain requiring further risk stratification. Traditional cardiac diagnostics such as stress testing may expose patients to ionizing radiation, may not be readily available, may take significant time for testing and interpretation, and adds cost to the workup. Magnetocardiography (MCG) is an alternative approach to assess candidates more quickly and efficiently than routine downstream testing.

Design

We created and ran 1000 trials of a Monte Carlo simulation. Using this simulation, we modeled the national annual impact by averting further cardiac diagnostics.

Setting

All EDs in the United States.

Participants

All ED adult patients with chest pain.

Interventions

Simulated use of MCG to reduce avoidable downstream cardiac diagnostics.

Main outcome measures

Our primary outcome was to estimate the impact of an MCG-first strategy on the annual national cost savings among eligible patients in the ED. Our secondary outcomes were the estimated reduction in short-stay hospitalizations, cancer cases, and cancer deaths due to radiation exposure.

Results

An MCG-first strategy was estimated to save a mean (±SD) of $574 million (±$175 million) by avoiding 555,000 (±93,000) downstream cardiac diagnostic tests. This resulted in a national annual cumulative decrease of 500,000 (±84,000) hospitalizations, 7,600,000 (±1,500,000) bed hours, 409 (±110) new cancer diagnoses, and 210 (±56) new cancer deaths due to radiation exposure from avoidable cardiac diagnostics.

Conclusions

If adopted widely and used consistently, an MCG-first strategy among eligible patients could yield substantial benefits by averting avoidable cardiac diagnostic testing.

Large-scale pretrained frame generative model enables real-time low-dose DSA imaging: An AI system development and multi-center validation study

BACKGROUND

Digital subtraction angiography (DSA) devices are commonly used in numerous interventional procedures across various parts of the body, necessitating multiple scans per procedure, which results in significant radiation exposure for both doctors and patients. Inspired by generative artificial intelligence techniques, this study proposes GenDSA, a large-scale pretrained multi-frame generative model-based real-time and low-dose DSA imaging system.

METHODS

GenDSA was developed to generate 1-, 2-, and 3-frame sequences following each real frame. A large-scale dataset comprising ∼3 million DSA images from 27,117 patients across 10 hospitals was constructed to pretrain, fine-tune, and validate GenDSA. Two other datasets from 25 hospitals were used for evaluation. Objective evaluations included SSIM and PSNR. Five interventional radiologists independently assessed the quality of the generated frames using the Likert scale and visual Turing test. Scoring consistency among the radiologists was measured using the Kendall coefficient of concordance (W). The Fleiss' kappa values were used for inter-rater agreement analysis for visual Turing tests.

FINDINGS

Using only one-third of the clinical radiation dose, videos generated by GenDSA were perfectly consistent with real videos. Objective evaluations demonstrated that GenDSA's performance (PSNR = 36.83, SSIM = 0.911, generation time = 0.07 s/frame) surpassed state-of-the-art algorithms. Subjective ratings and statistical results from five doctors indicated no significant difference between real and generated videos. Furthermore, the generated videos were comparable to real videos in overall quality (4.905 vs. 4.935) and lesion assessment (4.825 vs. 4.860).

CONCLUSIONS

With clear clinical and translational values, the developed GenDSA can significantly reduce radiation damage to both doctors and patients during DSA-guided procedures.

FUNDING

This study was supported by the National Key R&D Program and the National Natural Science Foundation of China.

DNA damage and repair in patients undergoing myocardial perfusion single-photon emission computed tomography

As patient exposure to ionizing radiation from medical imaging and its risks are continuing issues, this study aimed to evaluate DNA damage and repair markers after myocardial perfusion single-photon emission computed tomography (MPS). Thirty-two patients undergoing Tc-99m sestamibi MPS were studied. Peripheral blood was collected before radiotracer injection at rest and 60-90 min after injection. The comet assay (single-cell gel electrophoresis) was performed with peripheral blood cells to detect DNA strand breaks. Three descriptors were evaluated: the percentage of DNA in the comet tail, tail length, and tail moment (the product of DNA tail percentage and tail length). Quantitative PCR (qPCR) was performed to evaluate the expression of five genes related to signaling pathways in response to DNA damage and repair (ATM, ATR, BRCA1, CDKN1A, and XPC). Mann-Whitney's test was employed for statistical analysis; p < 0.05 was considered significant. Mean Tc-99m sestamibi dose was 15.1 mCi. After radiotracer injection, comparing post-exposure to pre-exposure samples of each of the 32 patients, no statistically significant differences of the DNA percentage in the tail, tail length or tail moment were found. qPCR revealed increased expression of BRCA1 and XPC, without any significant difference regarding the other genes. No significant increase in DNA strand breaks was detected after a single radiotracer injection for MPS. There was activation of only two repair genes, which may indicate that, in the current patient sample, the effects of ionizing radiation on the DNA were not large enough to trigger intense repair responses, suggesting the absence of significant DNA damage.

Evolving perspectives in reverse cardio-oncology: A review of current status, pathophysiological insights, and future directives

Cardiovascular disease (CVD) and cancer are leading causes of mortality worldwide, traditionally linked through adverse effects of cancer therapies on cardiovascular health. However, reverse cardio-oncology, a burgeoning field, shifts this perspective to examine how cardiovascular diseases influence the onset and progression of cancer. This novel approach has revealed a higher likelihood of cancer development in patients with pre-existing cardiovascular conditions, attributed to shared risk factors such as obesity, a sedentary lifestyle, and smoking. Underlying mechanisms like chronic inflammation and clonal hematopoiesis further illuminate the connections between cardiovascular ailments and cancer. This comprehensive narrative review, spanning a broad spectrum of studies, outlines the syndromic classification of cardio-oncology, the intersection of cardiovascular risk factors and oncogenesis, and the bidirectional dynamics between CVD and cancer. Additionally, the review also discusses the pathophysiological mechanisms underpinning this interconnection, examining the roles of cardiokines, genetic factors, and the effects of cardiovascular therapies and biomarkers in cancer diagnostics. Lastly, it aims to underline future directives, emphasising the need for integrated healthcare strategies, interdisciplinary research, and comprehensive treatment protocols.

Cardiac Imaging in Women with Ischemic Heart Disease

Cardiac diseases are the main cause of death for both sexes worldwide. Treatment varies widely according to the sex of a patient, as there are differences in physiopathology, epidemiology, clinical presentation and management. However, women have been largely excluded from research studies in this field. At present, differences are starting to be recognized and more attention is being paid to the identification of female-specific (or emergent) atherosclerotic risk factors. Diagnostic testing also merits attention because cardiac imaging offers important information to help diagnosis and guide cardiac disease management. In this sense, multimodal imaging should be used with the most cost-effective approach, integrating this information into the clinical sphere according to the pretest probability of the disease. In this review, we address sex-specific features of ischemic heart disease that should be considered in the clinical assessment of women, as well as the value of different imaging techniques (including technical and clinical aspects) for management of women with ischemic heart disease, and identify future areas of action concerning ischemic heart disease in women.

Algorithm for Reducing Overall Biological Detriment Caused by PET/CT: an Age-Based Study

Purpose

This study is to use a simple algorithm based on patient's age to reduce the overall biological detriment associated with PET/CT.

Materials and Methods

A total of 421 consecutive patients (mean age 64 ± 14 years) undergoing PET for various clinical indications were enrolled. For each scan, effective dose (ED in mSv) and additional cancer risk (ACR) were computed both in a reference condition (REF) and after applying an original algorithm (ALGO). The ALGO modified the mean dose of FDG and the PET scan time parameters; indeed, a lower dose and a longer scan time were reported in the younger, while a higher dose and a shorter scan time in the older patients. Moreover, patients were classified by age bracket (18-29, 30-60, and 61-90 years).

Results

The ED was 4.57 ± 0.92 mSv in the REF condition. The ACR were 0.020 ± 0.016 and 0.0187 ± 0.013, respectively, in REF and ALGO. The ACR for the REF and ALGO conditions were significantly reduced in males and females, although it was more evident in the latter gender (all p < 0.0001). Finally, the ACR significantly reduced from the REF condition to ALGO in all three age brackets (all p < 0.0001).

Conclusion

Implementation of ALGO protocols in PET can reduce the overall ACR, mainly in young and female patients.

Characteristics and key differences between patient populations receiving imaging modalities for coronary artery disease diagnosis in the US

BACKGROUND

There are limited data on the impact of imaging modality selection for the assessment of coronary artery disease (CAD) risk on downstream resource utilisation. This study sought to identify differences between patient populations in the US undergoing stress echocardiography, single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), positron emission tomography (PET) MPI, and coronary computed tomography angiography (cCTA) for the assessment of CAD risk, and associated physician referral patterns.

METHODS

Claims and electronic health records data for 2.5 million US patients who received stress echocardiography, cCTA, SPECT MPI or PET MPI between January 2016 and March 2018, from the Decision Resources Group Real-World Evidence US Data Repository, were analysed. Patients were stratified into suspected and existing CAD cohorts, and further stratified by pre-test risk and presence and recency of interventions or acute cardiac events (within 1-2 years pre-index test). Linear and logistic regression were used to compare numeric and categorical variables.

RESULTS

Physicians were more likely to refer patients to standalone SPECT MPI (77%) and stress echocardiography (18%) than PET MPI (3%) and cCTA (2%). Overall, 43% of physicians referred more than 90% of their patients to standalone SPECT MPI. Just 3%, 1% and 1% of physicians referred more than 90% of their patients to stress echocardiography, PET MPI or cCTA. At the aggregated imaging level, patients who underwent stress echocardiography or cCTA had similar comorbidity profiles. Comorbidity profiles were also similar for patients who underwent SPECT MPI and PET MPI.

CONCLUSION

Most patients underwent SPECT MPI at the index date, with very few undergoing PET MPI or cCTA. Patients who underwent cCTA at the index date were more likely to undergo additional imaging tests compared with those who underwent other imaging modalities. Further evidence is needed to understand factors influencing imaging test selection across patient populations.

Influence of intensive lipid-lowering on CT derived fractional flow reserve in patients with stable chest pain: Rationale and design of the FLOWPROMOTE study

INTRODUCTION

Coronary CT angiography (CTA) derived fractional flow reserve (FFR_CT ) shows high diagnostic performance when compared to invasively measured FFR. Presence and extent of low attenuation plaque density have been shown to be associated with abnormal physiology by measured FFR. Moreover, it is well established that statin therapy reduces the rate of plaque progression and results in morphology alterations underlying atherosclerosis. However, the interplay between lipid lowering treatment, plaque regression, and the coronary physiology has not previously been investigated.

AIM

To test whether lipid lowering therapy is associated with significant improvement in FFR_CT , and whether there is a dose-response relationship between lipid lowering intensity, plaque regression, and coronary flow recovery.

METHODS

Investigator driven, prospective, multicenter, randomized study of patients with stable angina, coronary stenosis ≥50% determined by clinically indicated first-line CTA, and FFR_CT  ≤ 0.80 in whom coronary revascularization was deferred. Patients are randomized to standard (atorvastatin 40 mg daily) or intensive (rosuvastatin 40 mg + ezetimibe 10 mg daily) lipid lowering therapy for 18 months. Coronary CTA scans with blinded coronary plaque and FFR_CT analyses will be repeated after 9 and 18 months. The primary endpoint is the 18-month difference in FFR_CT using (1) the FFR_CT value 2 cm distal to stenosis and (2) the lowest distal value in the vessel of interest. A total of 104 patients will be included in the study.

CONCLUSION

The results of this study will provide novel insights into the interplay between lipid lowering, and the pathophysiology in coronary artery disease.

Evaluation of DNA damage induced by ionizing radiation from myocardial perfusion imaging: a pilot study

Background

As patient exposure to ionizing radiation raises concern about malignancy risks, this study evaluated the effect of ionizing radiation on patients undergoing myocardial perfusion imaging (MPI) using the comet assay, a method for detection of DNA damage.

Methods

Patients without cancer, acute or autoimmune diseases, recent surgery or trauma, were studied. Gated single-photon myocardial perfusion imaging was performed with Tc-99m sestamibi. Peripheral blood was collected before radiotracer injection at rest and 60–90 min after injection. Single-cell gel electrophoresis (comet assay) was performed with blood lymphocytes to detect strand breaks, which determine a “comet tail” of variable size, visually scored by 3 observers in a fluorescence microscope after staining (0: no damage, no tail; 1: small damage; 2: large damage; 3: full damage). A damage index was calculated as a weighted average of the cell scores.

Results

Among the 29 individuals included in the analysis, age was 65.3 ± 9.9 years and 18 (62.1%) were male. The injected radiotracer dose was 880.6 ± 229.4 MBq. Most cells (approximately 70%) remained without DNA fragmentation (class 0) after tracer injection. There were nonsignificant increases of classes 1 and 2 of damage. Class 3 was the least frequent both before and after radiotracer injection, but displayed a significant, 44% increase after injection.

Conclusion

While lymphocytes mostly remained in class 0, an increase in class 3 DNA damage was detected. This may suggest that, despite a probable lack of biologically relevant DNA damage, there is still a need for tracer dose reductions in MPI.

Nuclear Cardiology in Women and Underrepresented Minority Populations

PURPOSE OF REVIEW

To outline sex-specific features of coronary artery disease (CAD) that should be considered in the assessment of women, including those from ethnic minority populations with suspected stable ischemic heart disease (IHD). Second, to determine the latest nuclear imaging tools available to assess microvascular CAD.

RECENT FINDINGS

Latest studies indicate that women are more likely to have ischemia with no obstructive coronary arteries (INOCA) and paradoxically have worse outcomes. Therefore, the evaluation of women with suspected IHD should include assessing microvascular and epicardial coronary circulation. The prevalence of CAD is increasing in younger women due to the increased cardiovascular disease (CVD) risk burden. CAD is often underrecognized in these patients. There is increasing recognition that INOCA is not benign and should be accurately diagnosed and managed. Nuclear imaging assesses the full spectrum of CAD from microvascular CAD to multivessel obstructive epicardial CAD. Further research on myocardial blood flow (MBF) assessment with PET MPI is needed.

Pathophysiology and Role of Coronary CT Angiography in Stable Angina

관상동맥질환의 임상적인 개념은 지난 10년 동안 패러다임의 변화를 보여왔다. 관상동맥질환은 대부분 진행성 질환이며, 관상동맥질환 환자는 질병 진행의 어느 시점에서도 급성 관상동맥 증후군에 직면할 수 있다. 이러한 임상적 맥락에서 2019년 유럽심장학회 가이드라인에서는 조기 진단과 꾸준한 관리가 필요한 관상동맥질환의 임상적인 중요성을 반영하여 “만성 관상동맥증후군”이라는 용어의 사용을 발표하였다. 최근 관상동맥 전산화단층촬영 혈관조영술을 이용한 관상동맥질환의 평가는 많은 발전을 이루었고, 안정형 협심증 또는 만성 관상동맥증후군 환자에서 관상동맥 전산화단층촬영 혈관조영술의 임상적 유용성은 초기 무증상 관상동맥질환의 발견에서부터 죽상경화판의 특성 분석 및 관상동맥질환의 치료 전략 결정에 도움을 주는 역할까지 관상동맥질환의 다양한 단계에 걸쳐 입증되고 있다. 이 종설에서는 안정형 협심증 환자의 이해를 돕는 병태생리를 설명하고 이에 대한 관상동맥 전산화단층촬영의 임상적 적용과 역할에 대해 알아보고자 한다.

Comparing feasibility of different tube voltages and different concentrations of contrast medium in coronary CT angiography of overweight patients

OBJECTIVES

To compare image quality, radiation dose, and iodine intake of coronary computed tomography angiography (CCTA) acquired by wide-detector using different tube voltages and different concentrations of contrast medium (CM) for overweight patients.

MATERIALS AND METHODS

A total of 150 overweight patients (body mass index≥25 kg/m2) who underwent CCTA are enrolled and divided into three groups according to scan protocols namely, group A (120 kVp, 370 mgI/ml CM); group B (100 kVp, 350 mgI/ml CM); and group C (80 kVp, 320 mgI/ml CM). The CT values, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure-of-merit (FOM) of all images are calculated. Images are subjectively assessed using a 5-point scale. In addition, the CT dose index volume (CTDIvol) and dose length product (DLP) of each patient are recorded. The effective radiation dose (ED) is also calculated. Above data are then statistically analyzed.

RESULTS

The mean CT values, SNR, CNR, and subjective image quality of group A are significantly lower than those of groups B and C (P < 0.001), but there is no significant difference between groups B and C (P > 0.05). FOMs show a significantly increase trend from group A to C (P < 0.001). The ED values and total iodine intake in groups B and C are 30.34% and 68.53% and 10.22% and 16.85% lower than those in group A, respectively (P < 0.001).

CONCLUSION

The lower tube voltage and lower concentration of CM based on wide-detector allows for significant reduction in iodine load and radiation dose in CCTA for overweight patients comparing to routine scan protocols. It also enhances signal intensity of CCTA and maintains image quality.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.

STRUCTURE

Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.

STRUCTURE

Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered. Structure: Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

Assessing the downstream value of first-line cardiac positron emission tomography (PET) imaging using real world Medicare fee-for-service claims data

BACKGROUND

Higher imaging quality makes cardiac positron emission tomography (PET) desirable for evaluation of suspected coronary artery disease (CAD). High cost of PET imaging may be offset by reduced utilization and/or improved outcomes.

METHODS

This retrospective observational study utilized Medicare fee-for-service dataset. Study participants had no CAD diagnosis within 1 year prior to initial imaging. The PET group (PET imaging) and propensity score matched comparison group (single photon emission computed tomography or stress echocardiography) underwent index imaging between January 2014 and December 2016. Outcomes were analyzed using generalized linear models.

RESULTS

Among 144,503 study subjects, 4619 (3.2%) had PET and 139,884 (96.8%) had conventional imaging. After matching, each group had 4619 patients (mean age 74 years, 59% female). The PET group had lower radiation exposure (3.8 milliSievert less per year, 95% CI - 3.96 to - 3.64, P < .0001) and unstable coronary syndrome (incidence rate ratio (IRR) 0.77, 95% CI 0.64-0.94, P = .008). The PET group experienced more hospital admissions (IRR 1.10, 95% CI 1.06-1.15, P < .0001), more use of percutaneous coronary intervention (IRR 1.24, 95% CI 1.02-1.50, P = 0.03), while similar mortality rate (hazard ratio 0.95, 95% CI 0.78-1.14, P = 0.55). The PET group had higher medical spending ($2358.2 vs $1774.3, difference = $583.9 per patient per month, P < .0001).

CONCLUSIONS

First-line PET imaging was not associated with reduced levels of utilization and spending. Clinical outcomes were mostly similar.

Ten things to know about ten imaging studies: A preventive cardiology perspective ("ASPC top ten imaging")

Knowing the patient's current cardiovascular disease (CVD) status, as well as the patient's current and future CVD risk, helps the clinician make more informed patient-centered management recommendations towards the goal of preventing future CVD events. Imaging tests that can assist the clinician with the diagnosis and prognosis of CVD include imaging studies of the heart and vascular system, as well as imaging studies of other body organs applicable to CVD risk. The American Society for Preventive Cardiology (ASPC) has published "Ten Things to Know About Ten Cardiovascular Disease Risk Factors." Similarly, this "ASPC Top Ten Imaging" summarizes ten things to know about ten imaging studies related to assessing CVD and CVD risk, listed in tabular form. The ten imaging studies herein include: (1) coronary artery calcium imaging (CAC), (2) coronary computed tomography angiography (CCTA), (3) cardiac ultrasound (echocardiography), (4) nuclear myocardial perfusion imaging (MPI), (5) cardiac magnetic resonance (CMR), (6) cardiac catheterization [with or without intravascular ultrasound (IVUS) or coronary optical coherence tomography (OCT)], (7) dual x-ray absorptiometry (DXA) body composition, (8) hepatic imaging [ultrasound of liver, vibration-controlled transient elastography (VCTE), CT, MRI proton density fat fraction (PDFF), magnetic resonance spectroscopy (MRS)], (9) peripheral artery / endothelial function imaging (e.g., carotid ultrasound, peripheral doppler imaging, ultrasound flow-mediated dilation, other tests of endothelial function and peripheral vascular imaging) and (10) images of other body organs applicable to preventive cardiology (brain, kidney, ovary). Many cardiologists perform cardiovascular-related imaging. Many non-cardiologists perform applicable non-cardiovascular imaging. Cardiologists and non-cardiologists alike may benefit from a working knowledge of imaging studies applicable to the diagnosis and prognosis of CVD and CVD risk - both important in preventive cardiology.

Safety and effectiveness of strategies to reduce radiation exposure to proceduralists performing cardiac catheterization procedures: a systematic review

OBJECTIVE

The objective of this systematic review was to synthesize the best available evidence on the effect of various radiation protection strategies on radiation dose received by proceduralists performing cardiac catheterization procedures involving fluoroscopy.

INTRODUCTION

Cardiac catheterization procedures under fluoroscopy are the gold standard diagnostic and treatment method for patients with coronary artery disease. The growing demand of procedures means that proceduralists are being exposed to increasing amounts of radiation, resulting in an increased risk of deterministic and stochastic effects. Standard protective strategies and equipment such as lead garments reduce radiation exposure; however, the evidence surrounding additional equipment is contradictory.

INCLUSION CRITERIA

Randomized controlled trials that compared the use of an additional radiation protection strategy with conventional radiation protection methods were considered for inclusion. The primary outcome of interest was the radiation dose received by the proceduralist during cardiac catheterization procedures.

METHODS

A three-step search was conducted in MEDLINE, CINAHL, Embase, and the Cochrane Library (CENTRAL). Trials published in the English language with adult participants were included. Trials published from database inception until July 2019 were eligible for inclusion. The methodological quality of the included studies was assessed using the JBI critical appraisal checklist for randomized controlled trials. Quantitative data were extracted from the included papers using the JBI data extraction tool. Results that could not be pooled in meta-analysis were reported in a narrative form.

RESULTS

Fifteen randomized controlled trials were included in the review. Six radiation protection strategies were assessed: leaded and unleaded pelvic or arm drapes, transradial protection board, remotely controlled mechanical contrast injector, extension tubing for contrast injection, real-time radiation monitor, and a reduction in frame rate to 7.5 frames per second. Pooled data from two trials demonstrated a statistically significant decrease in the mean radiation dose (P < 0.00001) received by proceduralists performing transfemoral cardiac catheterization on patients who received a leaded pelvic drape compared to standard protection. One trial that compared the use of unleaded pelvic drapes placed on patients compared to standard protection reported a statistically significant decrease (P = 0.004) in the mean radiation dose received by proceduralists.Compared to standard protection, two trials that used unleaded arm drapes for patients, one trial that used a remotely controlled mechanical contrast injector, and one trial that used a transradial protection board demonstrated a statistically significant reduction in the radiation dose received by proceduralists.Similarly, using a frame rate of 7.5 versus 15 frames per second and monitoring radiation dose in real-time radiation significantly lowered the radiation dose received by the proceduralist. One trial demonstrated no statistically significant difference in proceduralist radiation dose among those who used the extension tubing compared to standard protection (P = 1).

CONCLUSIONS

This review provides evidence to support the use of leaded pelvic drapes for patients as an additional radiation protection strategy for proceduralists performing transradial or transfemoral cardiac catheterization. Further studies on the effectiveness of using a lower fluoroscopy frame rate, real-time radiation monitor, and transradial protection board are needed.

Worldwide Variation in the Use of Nuclear Cardiology Camera Technology, Reconstruction Software, and Imaging Protocols

OBJECTIVES

This study sought to describe worldwide variations in the use of myocardial perfusion imaging hardware, software, and imaging protocols and their impact on radiation effective dose (ED).

BACKGROUND

Concerns about long-term effects of ionizing radiation have prompted efforts to identify strategies for dose optimization in myocardial perfusion scintigraphy. Studies have increasingly shown opportunities for dose reduction using newer technologies and optimized protocols.

METHODS

Data were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study) registry, a multinational, cross-sectional study comprising 7,911 imaging studies from 308 labs in 65 countries. The study compared regional use of camera technologies, advanced post-processing software, and protocol characteristics and analyzed the influence of each factor on ED.

RESULTS

Cadmium-zinc-telluride and positron emission tomography (PET) cameras were used in 10% (regional range 0% to 26%) and 6% (regional range 0% to 17%) of studies worldwide. Attenuation correction was used in 26% of cases (range 10% to 57%), and advanced post-processing software was used in 38% of cases (range 26% to 64%). Stress-first single-photon emission computed tomography (SPECT) imaging comprised nearly 20% of cases from all world regions, except North America, where it was used in just 7% of cases. Factors associated with lower ED and odds ratio for achieving radiation dose ≤9 mSv included use of cadmium-zinc-telluride, PET, advanced post-processing software, and stress- or rest-only imaging. Overall, 39% of all studies (97% PET and 35% SPECT) were ≤9 mSv, while just 6% of all studies (32% PET and 4% SPECT) achieved a dose ≤3 mSv.

CONCLUSIONS

Newer-technology cameras, advanced software, and stress-only protocols were associated with reduced ED, but worldwide adoption of these practices was generally low and varied significantly between regions. The implementation of dose-optimizing technologies and protocols offers an opportunity to reduce patient radiation exposure across all world regions.

Real-Time Multi-Modal Sensing and Feedback for Catheterization in Porcine Tissue

Objective: In this study, we introduce a multi-modal sensing and feedback framework aimed at assisting clinicians during endovascular surgeries and catheterization procedures. This framework utilizes state-of-the-art imaging and sensing sub-systems to produce a 3D visualization of an endovascular catheter and surrounding vasculature without the need for intra-operative X-rays. Methods: The catheterization experiments within this study are conducted inside a porcine limb undergoing motions. A hybrid position-force controller of a robotically-actuated ultrasound (US) transducer for uneven porcine tissue surfaces is introduced. The tissue, vasculature, and catheter are visualized by integrated real-time US images, 3D surface imaging, and Fiber Bragg Grating (FBG) sensors. Results: During externally-induced limb motions, the vasculature and catheter can be reliably reconstructed at mean accuracies of 1.9±0.3 mm and 0.82±0.21 mm, respectively. Conclusions: The conventional use of intra-operative X-ray imaging to visualize instruments and vasculature in the human body can be reduced by employing improved diagnostic technologies that do not operate via ionizing radiation or nephrotoxic contrast agents. Significance: The presented multi-modal framework enables the radiation-free and accurate reconstruction of significant tissues and instruments involved in catheterization procedures.

Artificial Intelligence for Optimization and Interpretation of PET/CT and PET/MR Images

Artificial intelligence (AI) has recently attracted much attention for its potential use in healthcare applications. The use of AI to improve and extract more information out of medical images, given their parallels with natural images and the immense progress in the area of computer vision, has been at the forefront of these advances. This is due to a convergence of factors, including the increasing numbers of scans performed, the availability of open source AI tools, and decreases in the costs of hardware required to implement these technologies. In this article, we review the progress in the use of AI toward optimizing PET/CT and PET/MRI studies. These two methods, which combine molecular information with structural and (in the case of MRI) functional imaging, are extremely valuable for a wide range of clinical indications. They are also tremendously data-rich modalities and as such are highly amenable to data-driven technologies such as AI. The first half of the article will focus on methods to improve PET reconstruction and image quality, which has multiple benefits including faster image acquisition, image reconstruction, and lower or even "zero" radiation dose imaging. It will also address the value of AI-driven methods to perform MR-based attenuation correction. The second half will address how some of these advances can be used to perform to optimize diagnosis from the acquired images, with examples given for whole-body oncology, cardiology, and neurology indications. Overall, it is likely that the use of AI will markedly improve both the quality and safety of PET/CT and PET/MRI as well as enhance our ability to interpret the scans and follow lesions over time. This will hopefully lead to expanded clinical use cases for these valuable technologies leading to better patient care.

Practice Pattern, Diagnostic Yield, and Long-Term Prognostic Impact of Coronary Computed Tomographic Angiography

Background Although guidelines recommend the use of coronary computed tomographic angiography (CTA) in patients with stable pain syndromes, the clinical benefits of the use of coronary CTA in a broad spectrum of patients is unknown. We evaluated the contemporary practice pattern and diagnostic yield of coronary CTA and their impact on the subsequent diagnostic-therapeutic cascade and clinical outcomes. Methods and Results We identified 39 906 patients without known coronary artery disease (CAD) who underwent coronary CTA between January 2007 and December 2013. The patients' demographic characteristics, risk factors, symptoms, results of coronary CTA, the appropriateness of downstream diagnostic and therapeutic interventions, and long-term outcomes (death or myocardial infarction) were evaluated. The number of coronary CTAs had increased over time, especially in asymptomatic patients. Coronary CTA revealed that 6108 patients (15.3%) had obstructive CAD (23.7% of symptomatic and 9.3% of asymptomatic patients). Subsequent cardiac catheterization was performed in 19.2% of symptomatic patients (appropriate, 80.6%) and in 3.9% of asymptomatic patients (appropriate, 7.9%). The 5-year rate of death or myocardial infarction was significantly higher in patients with obstructive CAD on CTA than those without (7.2% versus 3.0%; P<0.001; adjusted hazard ratio [95% CI], 1.34 [1.17-1.54]). However, obstructive CAD on CTA had limited added value over conventional risk factors for predicting death or myocardial infarction. Conclusions Although the use of coronary CTA had substantially increased, CTA had a low diagnostic yield for obstructive CAD, especially in asymptomatic patients. The use of CTA in asymptomatic patients seemed to have led to inappropriate subsequent diagnostic or therapeutic interventions without clinical benefit.

Coronary Computed Tomography Angiography From Clinical Uses to Emerging Technologies: JACC State-of-the-Art Review

Evaluation of coronary artery disease (CAD) using coronary computed tomography angiography (CCTA) has seen a paradigm shift in the last decade. Evidence increasingly supports the clinical utility of CCTA across various stages of CAD, from the detection of early subclinical disease to the assessment of acute chest pain. Additionally, CCTA can be used to noninvasively quantify plaque burden and identify high-risk plaque, aiding in diagnosis, prognosis, and treatment. This is especially important in the evaluation of CAD in immune-driven conditions with increased cardiovascular disease prevalence. Emerging applications of CCTA based on hemodynamic indices and plaque characterization may provide personalized risk assessment, affect disease detection, and further guide therapy. This review provides an update on the evidence, clinical applications, and emerging technologies surrounding CCTA as highlighted at the 2019 National Heart, Lung and Blood Institute CCTA Summit.

Worldwide Diagnostic Reference Levels for Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging: Findings From INCAPS

OBJECTIVES

This study sought to establish worldwide and regional diagnostic reference levels (DRLs) and achievable administered activities (AAAs) for single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).

BACKGROUND

Reference levels serve as radiation dose benchmarks to compare individual laboratories against aggregated data, helping to identify sites in greatest need of dose reduction interventions. DRLs for SPECT MPI have previously been derived from national or regional registries. To date there have been no multiregional reports of DRLs for SPECT MPI from a single standardized dataset.

METHODS

Data were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study), a cross-sectional, multinational registry of MPI protocols. A total of 7,103 studies were included. DRLs and AAAs were calculated by protocol for each world region and for aggregated worldwide data.

RESULTS

The aggregated worldwide DRLs for rest-stress or stress-rest studies employing technetium Tc 99m-labeled radiopharmaceuticals were 11.2 mCi (first dose) and 32.0 mCi (second dose) for 1-day protocols, and 23.0 mCi (first dose) and 24.0 mCi (second dose) for multiday protocols. Corresponding AAAs were 10.1 mCi (first dose) and 28.0 mCi (second dose) for 1-day protocols, and 17.8 mCi (first dose) and 18.7 mCi (second dose) for multiday protocols. For stress-only technetium Tc 99m studies, the worldwide DRL and AAA were 18.0 mCi and 12.5 mCi, respectively. Stress-first imaging was used in 26% to 92% of regional studies except in North America where it was used in just 7% of cases. Significant differences in DRLs and AAAs were observed between regions.

CONCLUSIONS

This study reports reference levels for SPECT MPI for each major world region from one of the largest international registries of clinical MPI studies. Regional DRLs may be useful in establishing or revising guidelines or simply comparing individual laboratory protocols to regional trends. Organizations should continue to focus on establishing standardized reporting methods to improve the validity and comparability of regional DRLs.

Computed tomography for myocardial characterization in ischemic heart disease: a state-of-the-art review

This review provides an overview of the currently available computed tomography (CT) techniques for myocardial tissue characterization in ischemic heart disease, including CT perfusion and late iodine enhancement. CT myocardial perfusion imaging can be performed with static and dynamic protocols for the detection of ischemia and infarction using either single- or dual-energy CT modes. Late iodine enhancement may be used for the analysis of myocardial infarction. The accuracy of these CT techniques is highly dependent on the imaging protocol, including acquisition timing and contrast administration. Additionally, the options for qualitative and quantitative analysis and the accuracy of each technique are discussed.

Computed tomography coronary angiography - past, present and future

Computed tomography coronary angiography (CTCA) is a robust and reliable non-invasive alternative imaging modality to invasive coronary angiography, which is the reference standard in evaluating the degree of coronary artery stenosis. CTCA has high negative predictive value and can confidently exclude significant coronary artery disease (CAD) in low to intermediate risk patients. Over the years, substantial effort has been made to reduce the radiation dose and increase the cost efficiency of CTCA. In this review, we present the evolution of computed tomography scanners in the context of coronary artery imaging as well as its clinical applications and limitations. We also highlight the future directions of CTCA as a one-stop non-invasive imaging modality for anatomic and functional assessment of CAD.

Diagnostic Value of Lesion-specific Measurement of Myocardial Blood Flow Using Hybrid PET/CT

BACKGROUND

We evaluated whether lesion-specific measurement of myocardial blood flow (MBF) and flow reserve (MFR) by hybrid imaging of myocardial perfusion positron emission tomography (PET) and coronary computed tomography (CT) can provide additional diagnostic value.

METHODS

Forty-three patients with stable angina underwent N-13 ammonia PET and coronary CT before invasive coronary angiography (CAG). The lesion-specific MBF was calculated from the average MBF of the myocardial segments downstream of a coronary stenosis using hybrid PET/CT images. The hyperemic MBF, resting MBF, and MFR were measured for the left anterior descending artery (LAD) using conventional and lesion-specific methods. The diagnostic accuracy was compared between the two methods for significant LAD stenoses (≥ 70% reference diameter on CAG).

RESULTS

There were 19 significant LAD stenoses. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were 71%, 68%, 74%, 65%, and 70% for conventional hyperemic MBF (optimal cutoff = 2.15 mL/min/g), 79%, 63%, 74%, 65%, and 70% for conventional MFR (optimal cutoff = 1.82), 83%, 74%, 80%, 78%, and 80% for lesion-specific hyperemic MBF (optimal cutoff = 1.75 mL/min/g), and 79%, 79%, 83%, 75%, and 79% for lesion-specific MFR (optimal cutoff = 1.86), respectively. The lesion-specific measurement was more accurate and had a better linear correlation with anatomical stenosis severity for both hyperemic MBF and MFR.

CONCLUSIONS

Lesion-specific measurement using hybrid PET/CT imaging showed significant improvement in the diagnostic accuracy of PET-measured hyperemic MBF and MFR.

Increased Cancer Incidence Following up to 15 Years after Cardiac Catheterization in Infants under One Year between 1980 and 1998-A Single Center Observational Study

OBJECTIVE

To evaluate the incidence of cancer within the first 15 years of life in children who underwent cardiac catheterization under the age of one year.

METHODS

In this retrospective, single center study, 2770 infants (7.8% with trisomy 21) were studied. All infants underwent cardiac catheterization under one year of age between January 1980 and December 1998. Newly diagnosed cancer in the first 15 years of life was assessed through record linkage to the German Childhood Cancer Registry (GCCR). Cancer risk in study patients was compared to the GCCR population of children less than 15 years. Patients with trisomy 21 were compared to the Danish Cytogenic Register for trisomy 21. Effective radiation doses were calculated for each tumor patient and 60 randomly selected patients who did not develop cancer.

RESULTS

In total, 24,472.5 person-years were analyzed. Sixteen children developed cancer, while 3.64 were expected (standardized incidence ratio (SIR) = 4.4, 95% confidence interval (CI): 2.5-7.2, p < 0.001). There was no preferred cancer type. The observed incidence of leukemia and solid tumors in trisomy 21 was only slightly higher (1 in 476 py) than expected (1 in 609 py, p = 0.64). There was no direct relationship between the radiation dose and the incidence of cancer.

CONCLUSION

Cardiac catherization in the first year of life was associated with a significantly increased cancer risk in a population with congenital heart disease.

Prone Myocardial Perfusion Imaging and Breast Attenuation: A Phantom Study

Background:

Soft tissue attenuation artifacts are the most common cause of misinterpretation in myocardial perfusion Imaging (MPI). Few studies assessing the value of prone imaging in women have been published. Breast attenuation artifacts can be present in up to 40% of the MPI studies in women.

Objectives:

This study aimed at evaluating the potential impact of prone MPI on breast attenuation, with a critical analysis of activity optimization and breast size influence.

Methods:

MPI of an Anthropomorphic Torso Phantom with silicone breast prostheses and equivalent adipose tissue was compared to a standard MPI database.

Results:

A medical qualitative and semiquantitative analysis demonstrated higher uptake in the LV anterior segments in the prone position for all injected activities. An artificial myocardium lesion was diagnosable in the right segment in all images, which shows that prone positioning would not mask a true lesion and it assists the cardiologist with a more accurate analysis. These results showed that it is possible to optimize the activity to be injected by up to 55.6% when using combined supine-prone images.

Conclusion:

Prone position has a high impact on the interpretation of MPI in female patients since it reduces the breast attenuation artifacts, and optimizes the radiation protection of the patient and all staff involved in the procedure, making it more cost-effective.

Radiation exposure during videourodynamic testing: Is dose reduction possible using a standardized protocol?

AIMS

To evaluate the impact of a protocol for standardized image capture during video urodynamics (VUD) on radiation exposure. Secondly, to categorize radiation exposure by condition warranting VUD and to identify clinical variables that correlate with increased radiation exposure.

METHODS

One hundred fifty patients underwent VUD using our standardized protocol. All images were taken using low dose and pulsed settings. Four images are captured: one scout image, one filling image, one voiding image, and one post-void image. If the patient is unable to void with the catheter in place, the catheter is removed and a second image is taken during an attempt at unintubated flow. If vesicoureteral reflux (VUR) is identified, an alternate protocol is entered to document parameters. The mean radiation exposure measured in dose area product (DAP), fluoroscopy time, and number of images were noted and compared with previously published fluoroscopy data collected at our institution before protocol implementation.

RESULTS

The mean fluoroscopy exposure after the implementation of our protocol was 273.5 mGy/cm² taking 5.2 images in 4.5 seconds. Protocol implementation leads to a 51.2% reduction in radiation exposure calculated by mean DAP (P < .0001) and a 96.5% reduction in fluoroscopy time (P < .0001). The presence of VUR, fluoroscopy time, and body mass index (BMI) > 25 were associated with higher radiation exposure (P < .0001).

CONCLUSION

Implementation and adherence to a standardized protocol for fluoroscopy led to a reduction in radiation exposure fluoroscopy time. The presence of VUR, fluoroscopy time, and BMI > 25 were associated with higher radiation exposure.

[Evaluation of the incidence of radiodermatitis lesions in interventional cardiology]

PURPOSE

The percutaneous coronary interventions use large doses of ionizing radiation, particularly when treating complex lesions. The incidence of radio-induced skin lesions is poorly known. Our goal was to evaluate the frequency of occurrence of such lesions, as well as the factors that may contribute to a high radiation dose. The recommended DAP (dose-area product) cutoff for skin monitoring after percutaneous coronary interventions is 500Gy cm².

PATIENTS AND METHOD

We prospectively studied the incidence of acute (after 5-7 days) and subacute (after 7 days to 6 months) skin lesions following angioplasty with a dose-area product (DAP) ≥200Gy cm² in patients who underwent coronary angioplasty in our center in 2013.

RESULTS

Nine hundred and thirty three consecutive procedures were analyzed, of which 102 with a DAP ≥200Gy cm². Three patients presented an acute lesion. Two of these three patients also had subacute lesions. Another patient presented only a subacute lesion. 4.82% (95% CI: [0-10]) of the patients with a DAP ≥200Gy cm² developed radiodermitis lesions, or 0.47% (95% CI: [0-0.9]) of all the patients who underwent angioplasty. The Body Mass Index and the elective (as opposed to energy) procedures were independently associated with a procedure with a DAP ≥200Gy cm².

CONCLUSION

Radiodermatitis lesions occur for 4.82% of patients benefiting from procedures with a DAP ≥200Gy cm². We suggest the establishment of a DAP threshold for dermal monitoring of patients of 200Gy cm² per procedure instead of 500Gy cm².

Relevance of Non-Targeted Effects for Radiotherapy and Diagnostic Radiology; A Historical and Conceptual Analysis of Key Players

Non-targeted effects (NTE) such as bystander effects or genomic instability have been known for many years but their significance for radiotherapy or medical diagnostic radiology are far from clear. Central to the issue are reported differences in the response of normal and tumour tissues to signals from directly irradiated cells. This review will discuss possible mechanisms and implications of these different responses and will then discuss possible new therapeutic avenues suggested by the analysis. Finally, the importance of NTE for diagnostic radiology and nuclear medicine which stems from the dominance of NTE in the low-dose region of the dose–response curve will be presented. Areas such as second cancer induction and microenvironment plasticity will be discussed.

Strategies for Minimizing Occupational Radiation Exposure in Cardiac Imaging

PURPOSE OF REVIEW

Radiation safety has been at the center of interest of both researchers and healthcare institutions. This review will summarize and shed light on the various techniques adapted to reduce staff exposure to ionizing radiation (IR) in the field of cardiac imaging.

RECENT FINDINGS

In the last years, with the advance of awareness and the development of new technologies, there have been several tools and techniques adapted. The breakthrough of several technologies to lower radiation dose and shorten the duration of diagnostic tests associated with IR, the use of protection devices by staff members, and mostly the awareness of exposure to IR are the hallmark of these advances. Using all these measures has led to a significant decrease in staff exposure to IR. Reducing staff exposure to meet the "As Low As Reasonably Achievable" principle is feasible. This review introduces the most important strategies applied in cardiac imaging.

Hybrid anatomo-functional imaging of coronary artery disease: Beneficial irrespective of its core components

Coronary artery disease (CAD) is the most common and important cause of ischemic heart disease, with major implications on global morbidity and mortality. Non-invasive testing is crucial in the diagnostic and prognostic work-up of patients with or at risk of CAD, and also to guide decision making in terms of pharmacologic and revascularization therapy. The traditional paradigm is to view anatomic (i.e., coronary computed tomography) and functional imaging (e.g., myocardial perfusion scintigraphy) tests as opposing alternatives. Such approach is too reductionist and does not capitalize on the strengths of each type of test while risking to overlook the inherent limitations. The combination of anatomic and functional tests in a logic of hybrid imaging holds the promise of overcoming the limitations inherent to anatomic and functional testing, enabling more accurate diagnosis, prognosis, and guidance for revascularization in patients with CAD.

Effectiveness of protection strategies for reducing radiation exposure in proceduralists during cardiac catheterization procedures: a systematic review protocol

REVIEW QUESTION

What is the effectiveness of radiation protection strategies for reducing the radiation dose received by the proceduralist during cardiac catheterization procedures?

Multisection computed tomography: Results from a Chinese survey on radiation dose metrics

BACKGROUND

As multisection spiral computed tomography (MSCT) have been extensively used, it is important to consider the amounts of doses the patients are exposed during a computed tomography (CT) examination. The aim of the current study was to summarize MSCT doses in Chinese patients to establish the diagnostic reference levels (DRLs).

METHODS

Radiation dose metrics were retrospectively collected from 164,073 CT examinations via the Radimetrics Enterprise Platform. Radiation dose metrics (volume CT dose index [CTDIvol], dose-length product [DLP], effective dose [ED], and organ dose) and size-specific dose estimate (SSDE) were calculated for adults and children based on anatomic area and scanner type.

RESULTS

The median CTDIvol and DLP values were highest in the head at 51.7 mGy (interquartile range [IQR], 33.2-51.7 mGy) and 906.5 mGy·cm (IQR, 582.4-1068.2 mGy·cm) and lowest in the chest at 7.9 mGy (IQR, 7.9-10.3 mGy) and 284.8 mGy·cm (IQR, 249.0-412.6 mGy·cm), respectively. The median SSDE values of chest and pelvis were 12.1 mGy (IQR, 10.8-14.1 mGy) and 36.3 mGy (IQR, 34.0-38.9 mGy), respectively. EDs for children were similar to adults except for an increased 1.5-, 0.77-, and 1.7-fold in the chest, neck, and pelvis, respectively (p < 0.001). Furthermore, radiation doses tended to increase with increasing slice number and decrease when exposure reduction techniques were used.

CONCLUSION

Our findings provide a basis for the evaluation of CT radiation doses and evidence for establishment of DRLs in China.