Image Quality and Radiation Exposure With Prospectively ECG-Triggered Axial Scanning for Coronary CT Angiography (original) (raw)
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Helical prospective ECG-gating in cardiac computed tomography: radiation dose and image quality
The International Journal of Cardiovascular Imaging, 2010
Helical prospective ECG-gating (pECG) may reduce radiation dose while maintaining the advantages of helical image acquisition for coronary computed tomography angiography (CCTA). Aim of this study was to evaluate helical pECG-gating in CCTA in regards to radiation dose and image quality. 86 patients undergoing 64-multislice CCTA were enrolled. pECG-gating was performed in patients with regular heart rates (HR) \ 65 bpm; with the gating window set at 70-85% of the cardiac cycle. All patients received oral and some received additional IV beta-blockers to achieve HR \ 65 bpm. In patients with higher or irregular HR, or for functional evaluation, retrospective ECG-gating (rECG) was performed. The average X-ray dose was estimated from the dose length product. Each arterial segment (modified AHA/ACC 17-segment-model) was evaluated on a 4-point image quality scale (4 = excellent; 3 = good, mild artefact; 2 = acceptable, some artefact, 1 = uninterpretable). pECG-gating was applied in 57 patients, rECG-gating in 29 patients. There was no difference in age, gender, body mass index, scan length or tube output settings between both groups. HR in the pECG-group was 54.7 bpm (range, 43-64). The effective radiation dose was significantly lower for patients scanned with pECG-gating with mean 6.9 mSv ± 1.9 (range, 2.9-10.7) compared to rECG with 16.9 mSv ± 4.1 (P \ 0.001), resulting in a mean dose reduction of 59.2%. For pECG-gating, out of 969 coronary segments, 99.3% were interpretable. Image quality was excellent in 90.2%, good in 7.8%, acceptable in 1.3% and non-interpretable in 0.7% (n = 7 segments). For patients with steady heart rates \65 bpm, helical prospective ECG-gating can significantly lower the radiation dose while maintaining high image quality.
International Journal of Cardiovascular Imaging, 2014
High-pitch prospective ECG-triggered helical (PTH) protocols for coronary computed tomography angiography (CCTA) have demonstrated adequate image quality (IQ) in small-scaled studies and highly selected patients. Clinical applicability in a general clinical population is uncertain. This study evaluated the implementation of a PTH protocol in a routine clinical cohort, focusing on IQ and radiation dose. The local scientific board approved the retrospective analysis and all patients signed an informed consent statement for usage of their data. In consecutive patients suspected of coronary artery disease CCTA was performed using a dual source 128-slice scanner. All patients with a regular heart rate \65 bpm underwent a PTH CCTA. IQ for each coronary segment was graded (1 = absence of artifacts to 4 = non-evaluable). In 664 (80.4 %) of 826 included patients [mean age ± standard deviation (SD) 57 ± 11, 65 % female, mean body mass index (BMI) ± SD 27 ± 9 kg m-2 ] PTH CCTA was acquired whereas in 162 (19.6 %) a non-PTH sequence was used. Reasons for not performing a PTH protocol were persistent high heart rate (41.6 %) or heart rate irregularity (58.4 %). Mean ± SD heart rates for PTH and non-PTH CCTA were 55 ± 5 and 65 ± 9 bpm, respectively, p \ 0.001. In the PTH group 92 % of the segments were of diagnostic quality (score 1-3), versus 87 % in the non-PTH group (p = 0.055). Per patient, mean IQ score was 1.19 and 1.21 respectively (lower is better; p = 0.012). Effective dose (including topogram, test bolus, and coronary calcium score), as calculated with a conversion factor of 0.014 mSv mGy-1 cm-1 was 1.6 ± 0.6 and 4.7 ± 2.6 mSv for the PTH and the non-PTH group respectively, (p \ 0.001). Performing high-pitch PTH sequences on a routine basis is feasible in the majority of patients with high IQ and significant reduction in radiation dose. Keywords Cardiac computed tomography Á CCTA Á Coronary computed tomography angiography Á High-pitch Á Flash Á Image quality Á Radiation dose
IOSR Journals , 2019
Background: Nowadaysamong non communicable diseases Coronary artery disease heads in both in mortality and morbidity.Its early detection and hence cure needs multimodal diagnostic tools CT scan being among the latest modality.The diagnostic value of conventional coronary angiography has been challenged by the emergence & fast growing use of a less invasive imaging technique, multislice computerised tomography (MSCT) angiography to avoid radiation hazard. From time to time ,the manufacturers have implemented strategies to reduce the radiation exposure and these include ECG-gated dose modulation, automated exposure control,lowering the tube voltage,& increasing the pitch value with the use of dual source CT scanners.The non-invasiveness of this technique being highly desirable replacing conventional invasive coronary angiography. Hence reducing risk of radiation exposure hence health care threats. Aim: The aim of our study was to assess & compare the radiation doses between the prospective & retrospective ECG-gated coronary CT angiography in CAD patients. Methods: We performed our study ,a prospective comparative study conducted in the Department of Radiodiagnosis & Imaging of a tertiary institute at Srinagar,Kashmir,India after taking due clearance from the Institutional Ethical Committee(IEC).Inclucluded Patients were low to intermediate risk for CAD and patients with high risk for CAD but were reluctant for undergoing an invasive procedure.99 patients were enrolled in the study for a total period of two years, underwent contrast-enhanced ECG-gated CT coronary angiography by either of the two methods. Results: In this study, we compared a new method of coronary CTA based on prospectively gated sequential axial acquisition(PGA CTA) with the retrospectively gated helical acquisition (RGH CTA) as the reference method in a total of 99 patients.We demonstrated an important and significant decrease in radiation dose by PGA CTA with an equivalent image quality and number of assessable segments compared with RGH CTA. Conclusion: with adequate preparation & careful patient selection, most patients can have a diagnostic CCTA exam with prospective gating &their effective radiation dose & subsequent risk of developing a radiationinduced malignancy can be greatly reduced. . Prospectively-gated acquisition (PGA CTA) has been specifically designed to reduce the of coronary CT angiography by limiting X-ray exposure to a brief predetermined diastole window & eliminating overlapping areas of exposure. Summary: Lower dose reduces the long-term risk to the patient of developing a radiation-induced malignancy. Consequently, reducing the radiation burden to the lowest level without compromising the diagnostic image quality should be the persistent goal for the radiologist.
The International Journal of Cardiovascular Imaging, 2010
We sought to determine the cut-off point of the average heart rate (HR) and HR differences in obtaining diagnostic image quality using prospective electrocardiographically-triggered (PT) coronary computed tomographic angiography (CCTA) and to compare image quality and radiation dose for CCTA obtained with PT CCTA and retrospective electrocardiographically-gated (RG) CCTA. A total of 178 patients who were referred for CCTA were enrolled in the study. Two independent radiologists evaluated subjective image quality. The non-diagnostic coronary segments were 32 of 1,226 segments (2.6%) for PT CCTA and 12 of 1,346 segments (0.9%) for RG CCTA (P < 0.001). The mean image quality scores for PT CCTA and RG CCTA were 3.82 +/- 0.29 and 3.93 +/- 0.14, respectively. The mean radiation dose of patients that underwent PT CCTA was 3.83 +/- 0.84 mSv and RG CCTA 10.7 +/- 2.70 mSv. For patients who underwent PT CCTA, image quality was inversely related to HR (56.5 +/- 4.3 bpm; r = 0.38; P < 0.001) and HR differences (2.8 +/- 2.7 bpm; r = 0.49; P < 0.001). With the use of receiver operator characteristic analysis, a cut-off HR of 57 bpm (58% sensitivity, 67% specificity) and HR difference of 6 bpm (93% sensitivity, 46% specificity) were the best threshold for the prediction of diagnostic image quality. In patients with a regular, low HR, PT CCTA offers diagnostic image quality and substantially reduces effective radiation compared with the use of RG CCTA with dose modulation.
Radiation Protection Dosimetry, 2013
A retrospective analysis was performed in patients undergoing prospective ECG-triggered coronary computed tomography (CT) angiography (CCTA) with the single-source 64-slice CT (SSCT), dual-source 64-slice CT (DSCT), dual-source 128slice CT and 320-slice CT with the aim of comparing the radiation dose associated with different CT generations. A total of 164 patients undergoing prospective ECG-triggered CCTA with different types of CT scanners were studied with the mean effective doses estimated at 6.8+ + + + +3.2, 4.2+ + + + +1.9, 4.1+ + + + +0.6 and 3.8+ + + + +1.4 mSv corresponding to the 128-slice DSCT, 64-slice DSCT, 64-slice SSCT and 320-slice CT scanners. In this study a positive relationship was found between the effective dose and the body mass index (BMI). A low radiation dose is achieved in prospective ECG-triggered CCTA, regardless of the CT scanner generation. BMI is identified as the major factor that has a direct impact on the effective dose associated with prospective ECG-triggered CCTA.
Clinical Radiology, 2010
To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded. There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square=15.331, p=0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71+/-0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p<0.001). Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.
The International Journal of Cardiovascular Imaging, 2009
Current 64-multidetector Computed Tomographic scanners (MDCT) utilize retrospective overlapping helical acquisition (RS-OHA) which imparts a higher than desired radiation dose. Although the radiation burden of computed tomographic angiography (CTA) can be efficiently reduced by dose modulation and limiting field of view, a further decrease in radiation without compromising diagnostic image quality would be indeed very desirable. An alternative imaging mode is the axial prospective ECG-triggering acquisition (prospective gating). This study was done to compare the effective radiation dose and the image quality with two techniques to reduce radiation doses with CTA studies utilizing 64-MDCT scanners. The study included 149 consecutive patients (48 females and 101 males) 64-MDCT (mean age = 67 ± 11 years, 72.2% male). Patients underwent CT coronary angiography using one of three algorithms: retrospective triggering with dose modulation; prospective triggering with padding (step and shoot acquisition with additional adjacent phases); and prospective triggering without padding (single phase acquisition only). Based on body habitus, two different voltages were utilized: 100 kVp (\85 kg) or 120 kVp ([85 kg). Radiation doses and image quality (signal to noise ratio) was measured for each patient, and compared between different acquisition protocols. The signal to-noise ratio of the ascending aorta (SNR-AA) was calculated from the mean pixel values of the contrast-filled left ventricular chamber divided by the standard deviation of these pixel values. Use of 100 kVp reduced radiation dose 41.5% using prospective triggering and 39.6% using retrospective imaging as compared to 120 kVp (P \ 0.001). Use of prospective imaging reduced radiation exposure by 82.6% as compared to retrospective imaging (P \ 0.001). Using both prospective imaging and 100 kVp without padding (single phase data, no other phases obtained), radiation dose was reduced by 90% (P \ 0.001). In terms of image quality, the coefficient of variation of ascending aortic contrast enhancement between kVp of 120 and kVp of 100 was 6% (1.05, 95 CI 0.93-1.17), and 7.8% (0.9, 95% CI 0.7-1.2) at the pulmonary artery. The prospective ECG-Triggered acquisition and 100 kVp images were of diagnostic quality, allowing adequate assessment in all patients. CTA using PA and 100 kVp reduced the radiation dose by up to 90% without compromising the image quality.
European Journal of Radiology, 2012
Purpose: To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT). Materials and methods: An ECG simulator (EKG Phantom 320, Müller & Sebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts.
Clinical Imaging, 2011
Purpose: To compare image quality and patient radiation dose in a group of patients who underwent 320-detector computed tomography coronary angiography performed with prospective electrocardiogram (ECG) gating with image quality and radiation dose in a group of patients matched for clinical features who underwent 320-detector computed tomographic (CT) coronary angiography performed with retrospective ECG gating. Materials and Methods: This study was approved by our institutional human research committee. All patients had clinical indications for coronary computed tomography angiography (CTA). Two independent reviewers separately scored coronary artery segment image quality for 480 cardiac CT studies in prospective group and retrospective group (240 in each group). Reviewer variability was calculated. Estimated effective radiation dose was compared for prospective versus retrospective ECG gating. Results: The two groups matched well for clinical characteristics and CT parameters. There was good agreement for coronary artery segment image quality scores between the independent reviewers (k=0.73). Of the 6408 coronary artery segments scored, there were no coronary artery segments that could not be evaluated in each group. Image quality scores were not significantly different (PN.05). Mean patient radiation dose was 76.50% lower for prospective gating (4.2 mSv) than for retrospective gating (18.1 mSv) (Pb.01). Conclusion: Use of 320-detector CT coronary angiography performed with prospective ECG gating has similar subjective image quality scores but 76.50% lower patient radiation dose when compared with use of retrospective ECG gating.
Scientific Reports, 2019
In this report we have evaluated radiation effective dose received by patients during ECG-gated CCTA examinations based on gender, heart rate, tube voltage protocol and body mass index (BMI). A total of 1,824 patients were retrospectively recruited (1,139 men and 685 women) and they were divided into Group 1 (CCTA with calcium scoring), Group 2 (CCTA without calcium scoring) and Group 3 (only calcium scoring), where the association between gender, heart rate, tube voltage protocol and body mass index (BMI) were analysed. Examinations were performed using a retrospective ECG-gated CCTA protocol and the effective doses were calculated from the dose length product with a conversion coefficient of 0.026 mSv.mGy−1cm−1. No significant differences were observed in the mean effective dose between gender in all groups. The mean estimated dose was significantly higher when the heart rate was lower in Group 1 (p < 0.001) and Group 2 (p = 0.002). There were also significant differences betwe...