Radiation risks from cardiovascular imaging tests

Improved image quality in CT pulmonary angiography using deep learning-based image reconstruction

We investigated the effect of deep learning-based image reconstruction (DLIR) compared to iterative reconstruction on image quality in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). For 220 patients with suspected PE, CTPA studies were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASiR-V 30%, 60% and 90%) and DLIR (low, medium and high strength). Contrast-to-noise ratio (CNR) served as the primary parameter of objective image quality. Subgroup analyses were performed for normal weight, overweight and obese individuals. For patients with confirmed PE (n = 40), we further measured PE-specific CNR. Subjective image quality was assessed independently by two experienced radiologists. CNR was lowest for FBP and enhanced with increasing levels of ASiR-V and, even more with increasing strength of DLIR. High strength DLIR resulted in an additional improvement in CNR by 29-67% compared to ASiR-V 90% (p < 0.05). PE-specific CNR increased by 75% compared to ASiR-V 90% (p < 0.05). Subjective image quality was significantly higher for medium and high strength DLIR compared to all other image reconstructions (p < 0.05). In CT pulmonary angiography, DLIR significantly outperforms iterative reconstruction for increasing objective and subjective image quality. This may allow for further reductions in radiation exposure in suspected PE.

Combined CT Coronary Artery Assessment and TAVI Planning

Computed tomography angiography (CTA) of the aorta and the iliofemoral arteries is crucial for preprocedural planning of transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis (AS), because it provides details on a variety of aspects required for heart team decision-making. In addition to providing relevant diagnostic information on the degree of aortic valve calcification, CTA allows for a customized choice of the transcatheter heart valve system and the TAVI access route. Furthermore, current guidelines recommend the exclusion of relevant coronary artery disease (CAD) prior to TAVI. The feasibility of coronary artery assessment with CTA in patients scheduled for TAVI has been established previously, and accumulating data support its value. In addition, fractional flow reserve determined from CTA (CT–FFR) and machine learning-based CT–FFR were recently shown to improve its diagnostic yield for this purpose. However, the utilization of CTA for coronary artery evaluation remains limited in this specific population of patients due to the relatively high risk of CAD coexistence with severe AS. Therefore, the current diagnostic work-up prior to TAVI routinely includes invasive catheter coronary angiography at most centers. In this article, the authors address technological prerequisites and CT protocol considerations, discuss pitfalls, review the current literature regarding combined CTA coronary artery assessment and preprocedural TAVI evaluation, and provide an overview of unanswered questions and future research goals within the field.

Exploring Vessel Wall Biology In Vivo by Ultrasensitive Total-Body PET

Ultrasensitive, high-resolution, extended-field-of-view total-body (TB) PET using the first-of-its-kind 194-cm axial-field-of-view uEXPLORER may facilitate the interrogation of biologic hallmarks of hitherto difficult-to-evaluate low-signal vessel wall pathology in cardiovascular disease. Methods: Healthy volunteers were imaged serially for up to 12 h after a standard dose of 18F-FDG (n = 15) or for up to 3 h after injection of a very low dose (about 5% of a standard dose; n = 15). A cohort undergoing standard 18F-FDG PET (n = 15) on a conventional scanner with a 22-cm axial field of view served as a comparison group. Arterial wall signal, crosstalk with hematopoietic and lymphoid organs, and image quality were analyzed using standardized techniques. Results: TB PET depicted the large vessel walls with excellent quality. The arterial wall could be imaged with high contrast up to 12 h after tracer injection. Ultralow-dose TB 18F-FDG images yielded a vessel wall signal and target-to-background ratio comparable to those of conventional-dose, short-axial-field-of-view PET. Crosstalk between vessel wall and lymphoid organs was identified with better accuracy in both TB PET cohorts than in conventional PET. Conclusion: TB PET enables detailed assessment of in vivo vessel wall biology and its crosstalk with other organs over an extended time window after tracer injection or at an ultralow tracer dose. These initial observations support the feasibility of serial imaging in low-risk populations and will stimulate future mechanistic studies or therapy monitoring in atherosclerosis and other vessel wall pathologies.

Effective doses for common paediatric diagnostic general radiography examinations at a major Australian paediatric hospital and the communication of associated radiation risks

INTRODUCTION

Health professionals in paediatric medical imaging are routinely required to communicate radiation risks to carers and patients. Effective dose alone cannot be used to specify and communicate the radiation risk for an individual as risks are dependent on many factors including age and patient sex. In this study, we estimated typical effective doses for 20 commonly performed paediatric general radiography examinations using the weight-based imaging protocols employed at a major Australian specialist paediatric hospital. Effective doses were used to estimate and categorise associated age-based stochastic risks with commonly used risk terminology to facilitate communication of risk.

METHODS

Paediatric protocols for common general radiography examinations and World Health Organization 50th percentile weight-for-age data for females and males aged up to 18 years were used to estimate typical effective doses using Monte Carlo software and lifetime risk of cancer incidence using published data. Results were used to determine standardised levels of risk using the Calman risk model.

RESULTS

Effective doses, corresponding lifetime risk of cancer incidence and level of risk category from 20 general radiography examinations for paediatric patients were calculated and presented for ease of communication. Doses ranged from <0.001 mSv (negligible risk) to 1.6 mSv (low risk).

CONCLUSION

Typical effective doses from common paediatric general radiography examinations, the associated lifetime risk of cancer incidence and level of risk have been established for our institution. This can be used to convey risks to health professionals, patients and carers in ways that are easy to understand and compare with other everyday risks.

PRECAUTION IN THE USE OF EFFECTIVE DOSE IN CORONARY CT ANGIOGRAPHY

The effective dose is a quantity used in clinical practice for statistical evaluation of the radiation dose of patients undergoing different types of examinations. Coronary computed tomography angiography (CCTA) is a specific examination whose calculated effective dose may be subject to several biases. For this reason, it is important to consider factors (different examination techniques, heart rate and patient habitus) that may influence its resulting value. Another critical factor is the methodological procedure for calculating the effective dose and cardiac-specific coefficient used to estimate effective dose from the dose-length product in computed tomography. Because CCTA is increasingly used in cardiology, it is recommended that the chest coefficient be replaced with a new cardiac coefficient when calculating the effective dose.

Echocardiography-Guided Percutaneous Patent Ductus Arteriosus Closure: 1-Year Single Center Experience in Indonesia

Introduction

Since the first successful percutaneous closure under transesophageal echocardiographic (TEE) guidance, many centers explored transcatheter procedures without fluoroscopy. This single-center study is aimed to show the feasibility and safety of percutaneous patent ductus arteriosus (PDA) closure under echocardiography-only guidance during our 1-year experience.

Methods

Patients with PDA were recruited for percutaneous PDA closure guided by either fluoroscopy or echocardiography-only in National Cardiovascular Center Harapan Kita (ClinicalTrials.gov Identifier: NCT05321849, clinicaltrials.gov/ct2/show/NCT05321849). Patients were evaluated clinically and radiologically using transthoracic echocardiography (TTE) at 6, 24, and 48 h after the procedure. The primary endpoint was the procedural success. Secondary endpoints were the procedural time and the rate of adverse events.

Results

A total of 60 patients underwent transcatheter PDA closure, 30 patients with fluoroscopy and 30 patients with echocardiography guidance. All patients had successful PDA closure. There were only residual shunts, which were disappeared after follow-up in both groups, but one patient with a fluoroscopy-guided procedure had moderate tricuspid regurgitation with suspected thrombus in the tricuspid valve. The procedural time was not significantly different between the fluoroscopy and echocardiography groups.

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.

Clinical Utility of SPECT in the Heart Transplant Population: Analysis From a Single Large-volume Center

BACKGROUND

Survival after heart transplant has greatly improved, with median survival now over 12 years. Cardiac allograft vasculopathy (CAV) has become a major source of long-term morbidity and mortality. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is used for CAV surveillance, but there is limited data on its prognostic utility.

METHODS

We retrospectively identified patients undergoing SPECT MPI for CAV surveillance at a single, large-volume center. Images were assessed with semiquantitative visual scoring (summed stress score [SSS] and summed rest score) and quantitatively with total perfusion defect (TPD).

RESULTS

We studied 503 patients (mean age 62.5, 69.3% male) at a median of 9.0 years post-transplant. During mean follow-up of 5.1 ± 2.5 years, 114 (22.6%) patients died. The diagnostic accuracy for significant CAV (ISHLT grade 2 or 3) was highest for SSS with an area under the curve of 0.650 and stress TPD (area under the curve, 0.648), with no significant difference between SSS and stress TPD (P = 0.061). Stress TPD (adjusted hazard ratio, 1.07; P = 0.018) was independently associated with all-cause mortality, while SSS was not (P = 0.064). The prognostic accuracy of quantitative assessment of perfusion tended to be higher compared with semiquantitative assessment, with the highest accuracy for stress TPD (area under the receiver operating curve 0.584).

CONCLUSIONS

While SPECT MPI identified a cohort of higher risk patients, with quantitative analysis of perfusion demonstrating higher prognostic accuracy. However, the overall prognostic accuracy was modest and alternative noninvasive modalities may be more suitable for CAV surveillance.

Simultaneous Percutaneous Interventional Treatment of Atrial Septal Defects and Pulmonary Valve Stenosis in Children Under the Guidance of Transoesophageal Echocardiography Alone: Preliminary Experiences

Objective

To investigate the efficacy and safety of simultaneous percutaneous interventional treatment of atrial septal defects (ASDs) and pulmonary valve stenosis (PS) in children under the guidance of transoesophageal echocardiography (TEE) alone.

Methods

Eleven children with ASD combined with PS who were treated at our hospital between March 2015 and March 2019 were recruited, including 4 males and 7 females. Preoperative transthoracic echocardiography showed that all patients had type II ASDs of the foramen ovale subtype, with a maximum diameter of 12.9 ± 2.7 mm (9.0–18.0 mm). The guiding principle of septal occluder selection is that the diameter of the occluder should be 2–4 mm larger than the maximum diameter of the ASD. The pressure gradient across the pulmonary valve in patients with PS was 54.7 ± 5.8 mmHg (47.0–64.0 mmHg), and a balloon with a diameter 1.2–1.4 times the diameter of the pulmonary valve annulus was used for dilatation. Effective dilatation was repeated 2–3 times. All children underwent ASD occlusion and PS balloon dilatation through the femoral vein under TEE guidance without radiation or contrast agents. The patients underwent PS balloon dilatation first, followed by ASD occlusion. The treatment effect was evaluated by TEE immediately after the procedure, and the patients were followed up regularly.

Results

All patients underwent successful simultaneous ASD occlusion and PS balloon dilatation through the femoral vein under the guidance of TEE alone. The pressure gradient across the pulmonary valve immediately after the procedure was 21.3 ± 1.8 mmHg (19.0–25.0 mmHg) (P < 0.01). No shunt was detected at the atrial septum level. The patients were followed for 3.0 ± 1.4 years (1.0–5.0 years) after the procedure. The atrial septal occluders were in the normal position in all of the patients, and there was no arrhythmia, hemolysis, or residual shunting. The pressure gradient across the pulmonary valve at 1 month after the procedure was 18.5 ± 3.3 mmHg (P < 0.01).

Conclusion

Simultaneous percutaneous interventional treatment of ASD and PS in children under the guidance of TEE alone is not only safe and effective but also prevents trauma caused by extracorporeal circulation and surgical incision and damage caused by X-ray and contrast agents. The surgical sequence included first performing PS balloon dilatation, followed by ASD occlusion.

Deep Learning-Based Image Reconstruction for CT Angiography of the Aorta

To evaluate the impact of a novel, deep-learning-based image reconstruction (DLIR) algorithm on image quality in CT angiography of the aorta, we retrospectively analyzed 51 consecutive patients who underwent ECG-gated chest CT angiography and non-gated acquisition for the abdomen on a 256-dectector-row CT. Images were reconstructed with adaptive statistical iterative reconstruction (ASIR-V) and DLIR. Intravascular image noise, the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were quantified for the ascending aorta, the descending thoracic aorta, the abdominal aorta and the iliac arteries. Two readers scored subjective image quality on a five-point scale. Compared to ASIR-V, DLIR reduced the median image noise by 51–54% for the ascending aorta and the descending thoracic aorta. Correspondingly, median CNR roughly doubled for the ascending aorta and descending thoracic aorta. There was a 38% reduction in image noise for the abdominal aorta and the iliac arteries, with a corresponding improvement in CNR. Median subjective image quality improved from good to excellent at all anatomical levels. In CT angiography of the aorta, DLIR substantially improved objective and subjective image quality beyond what can be achieved by state-of-the-art iterative reconstruction. This can pave the way for further radiation or contrast dose reductions.

The impact of current strategy using intracardiac echocardiography, lesion index, and minimum substrate ablation on clinical outcomes after catheter ablation procedure for atrial fibrillation

PURPOSE

We developed the intracardiac echocardiography (ICE) technique to minimize radiation exposure and other recent technology during ablation procedure for atrial fibrillation (AF). The aim of this study was to validate the impact of the current strategy using the recent technology for AF ablation on outcomes after procedure.

METHODS

We evaluated the safety and efficacy of the current strategy in consecutive set of patients undergoing first-time ablation for AF (N = 233) compared with the conventional strategy in earlier consecutive set of patients (N = 223). The current strategy included the technique of ICE to reduce radiation exposure, Ablation Index®-guided pulmonary veins isolation, and minimum substrate ablation targeting only for induced AF. Outcome measures were radiation exposure, procedure time, in-hospital adverse outcomes, and event-free survival from tachyarrhythmias.

RESULTS

Puncture-to-ablation time was slightly, but significantly increased in the current strategy than in the conventional strategy (48.0 minutes vs 44.7 minutes, P = .002), although total procedure time was significantly decreased in the current strategy (143.9 minutes vs 156.9 minutes, P < .001). Likewise, radiation time and absorbed dose were significantly decreased in the current strategy (9.8 minutes vs 38.8 minutes, P < .001; 102.3 mGy vs 490.5 mGy, P < .001). The incidence of overall in-hospital adverse outcomes was 3.9% in the current strategy and each complication rate was comparable with the conventional protocol. The event-free survival from recurrent atrial tachyarrhythmias was not significantly different between two groups (72.3% vs 77.1% at 2-year, P = .32).

CONCLUSION

The current strategy using the recent technology with ICE, lesion index, and minimum substrate ablation was feasible and reduced total procedure time and radiation exposure. However, the arrhythmia-free survival could not be improved.

Effective doses and associated age-related risks for common paediatric diagnostic nuclear medicine and PET procedures at a large Australian paediatric hospital

INTRODUCTION

Effective dose alone cannot be used to specify and communicate the radiation risk for an individual as risks are dependent on many factors including age and gender. There are limited published data regarding age-specific effective doses and the associated lifetime risk of developing cancers for paediatrics. In this study, we have estimated the typical effective doses for six commonly performed paediatric nuclear medicine and positron emission tomography (PET) studies at the Royal Children's Hospital, Melbourne, Australia. Effective doses were used to estimate and categorise associated stochastic risks with commonly used risk terminology.

METHODS

Paediatric protocols for common nuclear medicine and PET studies and the World Health Organization (WHO) 50th percentile weight-for-age data for females and males aged up to 18 years were used to estimate typical organ and effective doses using ICRP dosimetric tables for radiopharmaceuticals and lifetime risk of cancer incidence using BEIR VII Phase 2 report data. Results were used to determine standardised levels of risk.

RESULTS

Organ doses, effective doses, corresponding lifetime risk of cancer incidence and level of risk category from six common nuclear medicine and PET studies for paediatric patients were calculated and presented for ease of communication.

CONCLUSION

Typical effective doses from common paediatric nuclear medicine and PET studies and the associated lifetime risk of cancer incidence and level of risk have been established for our institution. This can be used to convey risks to health professionals, patients and carers in ways that are easy to understand and compare with other everyday risks.

Impact of Deep Learning-based Optimization Algorithm on Image Quality of Low-dose Coronary CT Angiography with Noise Reduction: A Prospective Study

RATIONALE AND OBJECTIVES

To evaluate deep learning (DL)-based optimization algorithm for low-dose coronary CT angiography (CCTA) image noise reduction and image quality (IQ) improvement.

MATERIALS AND METHODS

A postprocessing platform for the CCTA image was built using a DL-based algorithm. Seventy subjects referred for CCTA were randomly divided into two groups (study group A with 80 kVp and control group B with 100 kVp). Group C was obtained by DL optimization of group A. Subjective IQ was blindly graded by two experienced radiologists on a four-point scale (4-excellent,1-poor). The image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated to evaluate IQ objectively. The difference between the time consumed of iterative reconstruction and DL algorithm was also recorded.

RESULTS

The subjective IQ score of group C using the DL algorithm was significantly better than that of group A (p = 0.005). The noise of group C was significantly decreased, while SNR and CNR were significantly increased compared to group A (p < 0.001). The subjective IQ scores were lower in group A compared to group B (p = 0.037), whereas subjective IQ scores in group C were not significantly different (p = 0.874). For objective IQ, the noise of group A was significantly higher, while SNR and CNR were significantly lower than that of group B (p < 0.05). There was no significant difference in noise and SNR between group C and group B (p > 0.05), but CNR in group C was significantly higher than that in group B (p < 0.05). The DL algorithm processes the image twice as fast as the iterative reconstruction speed.

CONCLUSION

The DL-based optimization algorithm could effectively improve the IQ of low-dose CCTA by noise reduction.

Percutaneous device closure of pediatirc patent ductus arteriosus through femoral artery guidance by transthoracic echocardiography without radiation and contrast agents

Background

For many years, percutaneous interventional occlusion of congenital patent ductus arteriosus (PDA) has been completed using radiation and contrast agents. In this study, transthoracic echocardiography without radiation and contrast agents was used to complete percutaneous occlusion of pediatric PDA.

Methods

Thirty-two children (8 males and 24 females) with normal heart function and no other intracardiac deformities were diagnosed with PDA (20 funnel type; 12 tube type), One patient had peripheral facial paralysis, 1 patient had epilepsy, and 1 case had multiple cervical deformities. All procedures were performed in the surgical operating room (without Digital Subtraction Angiography (DSA) equipment) under basic anesthesia through the femoral artery pathway. The procedures were guided by transthoracic echocardiography (TTE) by establishing an orbit with a catheter through the femoral artery to thepatent ductus arteriosus,pulmonary artery and right ventricle. A suitable ventricular septal defect occluder was placed using the femoral artery approach,and the treatment effect was evaluated by echocardiography after occlusion. The Outpatient follow-up was performed at 1, 3 months after the operation.

Results

All cases had successful closure of PDA, which took only 35.6 ± 6.4 min. The diameter of the device was 4.8 ± 2.3 mm, and the heart murmur disappeared. There was no shunt between the left pulmonary artery and the descending aortic artery, and the length of hospitalization was 3.4 ± 0.5 days. No other incisions were needed in 32 cases. No occluder was removed, and no residual shunt was found after operation; moreover, no ICU stay was needed, and the mean hospital stay was 3.4 ± 0.5 days. No residual shunt was found at the 1-, 3-month follow-up visit.

Conclusions

PDA closure guided by transthoracic echocardiography via femoral artery puncture is a minimally invasive procedure that avoids injuries due to radiation and contrast agents. This method has wider application prospects in pediatrics.

Ultrasound-Guided Percutaneous Balloon Aortic Valvuloplasty for Aortic Stenosis

Percutaneous balloon aortic valvuloplasty (PBAV), which is used to treat symptomatic aortic stenosis, requires ionizing radiation and contrast agent for imaging guidance. The aim of the study is to evaluate the feasibility and effectiveness of ultrasound-guided PBAV in patients with aortic stenosis. This case series included 30 patients (14 males; mean age, 61.5 ± 4.5 years) with moderate/severe aortic stenosis treated with ultrasound-guided PBAV at the Ultrasound Department, Fuwai Hospital, Beijing, China, between January 2016 and July 2019. Cardiac function (New York Heart Association grade) was assessed before PBAV and 1 month after the procedure. Aortic peak jet velocity, aortic valve orifice area (AVA), mean transvalvular pressure gradient (MTPG), left ventricular end-diastolic diameter (LVDD), left ventricular ejection fraction (LVEF), and left ventricular end-systolic diameter (LVESD) were determined before and immediately after PBAV using Doppler echocardiography. Preprocedural cardiac function was grade I in 3 cases, grade II in 9 cases, grade III in 10 cases, and grade IV in 8 cases. Postprocedural cardiac function was grade I in 22 cases, grade II in 4 cases, and grade III in 4 cases, suggesting that cardiac function was improved by PBAV. Ultrasound-guided PBAV resulted in significant improvements (P < 0.05) in aortic peak jet velocity (3.68 ± 0.811 m/s vs. 4.79 ± 0.63 m/s), MTPG (33.77 ± 13.85 mmHg vs. 54.54 ± 13.81 mmHg), AVA (1.96 ± 0.25 cm² vs. 0.98 ± 0.12 cm²), LVEDD (51.90 ± 3.21 mm vs. 65.60 ± 6.81 mm), LVEF (63.46 ± 11.29% vs. 56.31 ± 11.04%), and LVESD (35.50 2.62 mm vs. 45.20 ± 2.42 mm). Ultrasound-guided PBAV is feasible and achieves good short-term effects in patients with aortic stenosis.

Percutaneous closure of patent foramen ovale under transthoracic echocardiography guidance-midterm results

Background

Conventional percutaneous closure of patent foramen ovale (PFO) is usually performed under the guidance of fluoroscopy. Whether closure of PFO under transthoracic echocardiography (TTE) guidance only is safe and effective is unknown. The present study therefore aimed to assess the safety and efficacy of percutaneous closure of PFO under TTE guidance only.

Methods

This study retrospectively enrolled a total of 52 consecutive patients (55.8% male, mean age 34.0±13.0 years, range, 10-59 years) with PFO treated at our institution from June 2015 to September 2017 by percutaneous closure under echocardiographic guidance only. The patients mean body weight was 58.7±10.8 kg. Patients underwent follow-up by TTE immediately post procedure by electrocardiogram and TTE at 1, 3, 6 and 12 months after discharge and annually thereafter, and by clinical evaluation at all time points.

Results

Of the 52 patients, 47 (90.4%) were successfully treated by percutaneous closure under TTE guidance. The mean procedure duration (from puncture to sheath removal) was 21.0±6.2 (range, 11-33) minutes. A trivial residual shunt which disappeared 24 hours later was observed in only 1 (1.9%) patient immediately post procedure. Median hospital stay was 3.0 days without severe complications such as peripheral vascular injury or cardiac perforation at discharge. At median 15.5 (11.3, 18.0) months follow-up, there were no complications such as death, stroke, transient ischemic attack (TIA) and residual shunt.

Conclusions

In this single center study of mostly lean patients, percutaneous closure of PFO under TTE guidance as the only imaging tool appeared effective at midterm follow-up, while avoiding radiation exposure, endotracheal intubation and contrast agent use.

Single-Shot Coronary Quiescent-Interval Slice-Selective Magnetic Resonance Angiography Using Compressed Sensing: A Feasibility Study in Patients With Congenital Heart Disease

OBJECTIVE

The aim of this study was to determine whether it is feasible to visualize the coronary origins in patients with congenital heart disease (CHD) using single-shot coronary quiescent-interval slice-selective (QISS) magnetic resonance angiography (MRA) with compressed sensing (CS).

METHODS

This retrospective study leveraged a parent study, which aimed to compare breath-hold, 2.1-fold accelerated, 2-shot coronary QISS MRA and clinical standard contrast-enhanced (CE) MRA in 14 patients with CHD (mean age, 17.0 ± 8.6 years, 6 females and 8 males). We evaluated the feasibility of single-shot coronary QISS MRA by retrospectively undersampling the 2-shot data set by an additional factor of 2, performing CS reconstruction, and comparing the retrospectively derived single-shot QISS MRA to 2-shot coronary QISS MRA and clinical standard CE MRA. For quantitative analysis, structural similarity index and normalized root mean square error were calculated. For qualitative analysis, 2 experienced readers scored the conspicuity of coronary origins on a 5-point Likert scale (1 = nondiagnostic, 2 = poor, 3 = clinically acceptable, 4 = good, 5 = excellent).

RESULTS

Compared with 2-shot QISS, single-shot QISS produced normalized root mean square error of 5.8% ± 0.8% and structural similarity index of 95.4% ± 1.6%, suggesting high data fidelity by CS reconstruction. Compared with the mean conspicuity scores for clinical CE MRA (4.2 ± 0.5 and 4.1 ± 0.6 for right and left coronary origins, respectively), the mean conspicuity scores were not significantly different (P > 0.3) for 2-shot QISS (4.4 ± 0.9 and 4.2 ± 1.1, respectively) and single-shot QISS with CS (4.3 ± 1.1 and 3.8 ± 1.3, respectively) and deemed clinically acceptable to good (scores ≥3.0).

CONCLUSIONS

This study shows that it is feasible to visualize the coronary origins in patients with CHD with clinically acceptable to good image quality using single-shot coronary QISS MRA with CS.

A Novel Wire Is Effective for Echo-Guiding Percutaneous Atrial Septal Defect Closure: A Preclinical Study

Objective

To assess the effectiveness of a novel ultrasound wire for echo-guiding percutaneous atrial septal defect (ASD) closure in a sheep model.

Methods

After right lateral thoracotomy, ASDs were created in 20 sheep by transseptal needle puncture followed by balloon dilatation. Animals were evenly randomized into 2 groups to undergo ASD closure using echography as the only imaging tool with either COOK wire (control group) or new ultrasound wire (study group). The total procedural time, passing time (time needed for the guide wire to enter the left atrium), frequency of delivery sheath dropping into the right atrium, frequency of arrhythmias, and 1-week rate of complications were compared between the two groups.

Results

All animals survived defect creation procedures uneventfully. ASD devices were successfully implanted in all sheep. Compared with the control group, the study group had significantly (P < 0.05) lower mean procedure time (15.36 ± 4.86 versus 25.82 ± 7.85 min), lower mean passing time (2.69 ± 0.82 versus 5.58 ± 3.34 min), lower frequency of the guide wire dropping into the right atrium (0% versus 40%), and lower frequency of atrial (4.41 ± 2.61 versus 9.60 ± 3.68) or ventricular premature contractions (0.75 ± 0.36 versus 1.34 ± 0.68), respectively, without serious complications up to one week.

Conclusion

The novel ultrasound specialized guide wire was effective in echo-guiding percutaneous ASD closure.

Feasibility and effectiveness of percutaneous balloon mitral valvuloplasty under echocardiographic guidance only

OBJECTIVE

Percutaneous balloon mitral valvuloplasty (PBMV) is the treatment of choice in patients with isolated mitral stenosis. This study aimed to assess the feasibility of PBMV under echocardiography guidance only of isolated mitral stenosis (MS).

METHODS

From October 2016 to Dec 2017, 20 consecutive patients with severe MS underwent PBMV with echocardiography as the only imaging modality at a single center. Outpatient follow-up including chest radiography, electrocardiography, and transthoracic echocardiography was conducted at 1, 3,6, and 12 months after the procedure.

RESULTS

All 20 patients successfully underwent PBMV under echocardiography guidance without radiation and contrast agent. Among them, 2 patients were pregnant, 5 had chronic renal failure, and 1 had history of allergy to contrast. Mitral transvalvular pressure gradient measured at catheterization dropped from 13.35 ± 2.85 mm Hg to 5.10 ± 1.17 mm Hg (P < .01). Mitral valve area increased from 0.82 ± 0.10 cm² pre-PBMV to 1.88 ± 0.24 cm² post-PBMV (P < .01). Mean balloon diameter was 26.63 ± 0.93 mm. Mild mitral regurgitation developed in 6 patients. Mean follow-up duration was 6.27 ± 3.12 months. At last follow-up, mitral valve area remained high (1.71 ± 0.14 cm² ) and mean transmitral pressure gradient low (6.07 ± 1.03 mm Hg). No pericardial effusion or peripheral vascular complications occurred.

CONCLUSION

In this small experience, PBMV could be successfully performed under only echocardiography guidance and appeared safe and effective while avoiding radiation and contrast agent use.

Radiobiology in Cardiovascular Imaging

The introduction of ionizing radiation in medicine revolutionized the diagnosis and treatment of disease and dramatically improved and continues to improve the quality of health care. Cardiovascular imaging and medical imaging in general, however, are associated with a range of radiobiologic effects, including, in rare instances, moderate to severe skin damage resulting from cardiac fluoroscopy. For the dose range associated with diagnostic imaging (corresponding to effective doses on the order of 10 mSv [1 rem]), the possible effects are stochastic in nature and largely theoretical. The most notable of these effects, of course, is the possible increase in cancer risk. The current review addresses radiobiology relevant to cardiovascular imaging, with particular emphasis on radiation induction of cancer, including consideration of the linear nonthreshold dose-response model and of alternative models such as radiation hormesis.

Cancer Risks in U.S. Radiologic Technologists Working With Fluoroscopically Guided Interventional Procedures, 1994-2008

OBJECTIVE

The purpose of this study was to examine risks of cancer incidence and mortality among U.S. radiation technologists performing or assisting with fluoroscopically guided interventional procedures.

SUBJECTS AND METHODS

A nationwide prospective cohort of 90,957 radiologic technologists, who responded to a 1994-1998 survey that collected information on whether they had ever worked with fluoroscopically guided interventional procedures, was followed through completion of a subsequent cohort survey during 2003-2005 (for cancer incidence) or December 31, 2008 (for cancer mortality). Sex-adjusted hazard ratios (HRs) and 95% CIs were calculated by use of Cox proportional hazards models for incidence and mortality from all cancers other than nonmelanoma skin cancer and for specific cancer outcomes in participants who reported ever performing fluoroscopically guided interventional procedures compared with technologists who never performed these procedures.

RESULTS

The analysis showed an approximately twofold increased risk of brain cancer mortality (HR, 2.55; 95% CI, 1.48-4.40) and modest elevations in incidence of melanoma (HR, 1.30; 95% CI, 1.05-1.61) and in breast cancer incidence (HR, 1.16; 95% CI, 1.02-1.32) but not mortality (HR, 1.07; 95% CI, 0.69-1.66) among technologists who performed fluoroscopically guided interventional procedures compared with those who never performed these procedures. Although there was a small suggestive increase in incidence of all cancers combined, excluding nonmelanoma skin cancers (HR, 1.08; 95% CI, 1.00-1.17), mortality from all cancers combined, excluding nonmelanoma skin cancers, was not elevated (HR, 1.00; 95% CI, 0.88-1.14). We similarly observed no elevated risk of cancers of the thyroid, skin other than melanoma, prostate, lung, or colon and rectum or of leukemia that was not chronic lymphocytic leukemia among workers who performed fluoroscopically guided interventional procedures.

CONCLUSION

We observed elevated risks of brain cancer, breast cancer, and melanoma among technologists who performed fluoroscopically guided interventional procedures. Although exposure to low-dose radiation is one possible explanation for these increased risks, these results may also be due to chance or unmeasured confounding by nonradiation risk factors. Our results must be confirmed in other studies, preferably with individual radiation dose data.

Image quality, radiation dose, and diagnostic accuracy of prospectively ECG-triggered high-pitch coronary CT angiography at 70 kVp in a clinical setting: comparison with invasive coronary angiography

PURPOSE

To investigate image quality, radiation dose, and diagnostic performance of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) at 70 kVp compared to invasive coronary angiography (ICA) as reference standard.

MATERIALS AND METHODS

Forty-three patients underwent prospectively ECG-triggered high-pitch CCTA at 70 kVp using 30 cc (11 g iodine) contrast medium and ICA. Subjective and objective image quality was evaluated for each CCTA study. CCTA performance for diagnosing ≥50% stenosis was assessed. Results were stratified according to heart rate (HR), body mass index (BMI), Agatston score, and image quality.

RESULTS

At CCTA, 94.3% (500/530) of coronary segments were of diagnostic quality. Using ICA as reference standard, sensitivity and accuracy were 100% and 93.0% on a per-patient basis. Per-vessel and per-segment performances were 92.2% and 89.5%; 79.5% and 88.3%, respectively. No differences were found in diagnostic accuracy between different HR, BMI, and calcification subgroups (all P > 0.05) on a per-patient basis. However, low image quality reduced diagnostic accuracy on a per-patient, per-vessel and per-segment basis (all P < 0.05). The mean effective radiation dose was 0.2 ± 0.0 mSv.

CONCLUSION

Our presented protocol results in an effective radiation dose of 0.2 mSv and high diagnostic accuracy for stenosis detection in a selected, non-obese population.

KEY POINTS

Prospectively ECG-triggered high-pitch CCTA at 70 kVp is feasible. This protocol has a high diagnostic accuracy for stenosis detection. The mean effective radiation dose was 0.2 ± 0.0 mSv. Only 30 cc of contrast material is used in this protocol. Low image quality reduced diagnostic accuracy of CCTA.

Approach to chest computed tomography

Computed tomography (CT) is central to the detection and diagnosis of a wide variety of pulmonary, cardiovascular, and other diseases of the chest. Successful interpretation of thoracic CT requires both an appreciation of the spectrum of normal appearances of the chest and a systematic approach to the characterization of thoracic pathology. This article provides an introduction to basic CT techniques and protocols, a review of normal CT anatomy, and an overview of commonly encountered abnormalities.

Reducing radiation exposure during invasive coronary angiography and percutaneous coronary interventions implementing a simple four-step protocol

BACKGROUND

With an increasing number of complex and repeated percutaneous coronary interventions (PCI), radiation-induced hazards for patients and operators remain an important issue in fluoroscopy-guided procedures. Our objective was to evaluate radiation exposure during coronary angiographic procedures and assess the efficacy of a four-step program to reduce radiation exposure during coronary angiography (CAG) and PCI.

METHODS AND RESULTS

A retrospective single-center analysis was performed in patients undergoing CAG or PCI in the first 6 months of 2012 vs. the first 6 months of 2014 (n = 3,107 procedures). During 2013, a four-step protocol was established in our hospital. It contained measures to reduce radiation exposure, including a frame rate reduction from 15 to 7.5 frames per second, the use of fluoroscopy storage, strict use of beam collimation, and repeat training on radiation safety. After adjustment for confounding variables, a dose-area product (DAP) reduction of 54.2% was observed subsequent to implementation of the four-step protocol. Independent predictors of DAP were age [odds ratio (OR) 1.01], body surface area (OR 5.47), prior coronary artery bypass grafting (OR 1.44), radial access (OR 1.16), PCI (OR 2.36), female gender (OR 0.91), and the implementation of the four-step program (OR 0.46).

CONCLUSION

A simple four-step protocol led to a significant reduction in radiation exposure in diagnostic and interventional coronary procedures without significant drawbacks in image quality. Hence, radiation safety programs are of paramount importance and should be established to improve patient and operator safety with regard to radiation-induced hazards.