Radiation reduction with prospective ECG-triggering acquisition using 64-multidetector computed tomographic angiography (original) (raw)
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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.
European Journal of Radiology, 2010
Objective: To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120 kV setting in cardiac computed tomography angiography (CCTA). Methods: 103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100 kV group: 51 patients; 120 kV group: 52 patients). Inclusion criteria were: (1) BMI <28 kg/m 2 ; (2) weight <85 kg; (3) coronary calcium score <300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale.
JACC: Cardiovascular Imaging, 2012
The purpose of this study was to evaluate image quality and radiation dose using a prospectively electrocardiogram (ECG)-triggered axial scan protocol compared with standard retrospective ECG-gated helical scanning for coronary computed tomography angiography. B A C K G R O U N D Concerns have been raised regarding radiation exposure during coronary computed tomography angiography. Although the use of prospectively ECG-triggered axial scan protocols may effectively lower radiation dose compared with helical scanning, it is unknown whether image quality is maintained in a clinical setting. M E T H O D S In a prospective, multicenter, multivendor trial, 400 patients with low and stable heart rates were randomized to either an axial or a helical coronary computed tomography angiography scan protocol. The primary endpoint was to demonstrate noninferiority in image quality with the axial scan protocol, which was assessed on a 4-point scale (1 ϭ nondiagnostic, 4 ϭ excellent image quality). Secondary endpoints included radiation dose and the rate of downstream testing during 30-day follow-up. R E S U L T S Image quality in patients scanned with the axial scan protocol (score 3.36 Ϯ 0.59) was not inferior compared with helical scan protocols (3.37 Ϯ 0.59) (p for noninferiority Ͻ0.004). Axial scanning was associated with a 69% reduction in radiation exposure (dose-length product [estimated effective dose] 252 Ϯ 147 mGy • cm [3.5 Ϯ 2.1 mSv] vs. 802 Ϯ 419 mGy • cm [11.2 Ϯ 5.9 mSv] for axial vs. helical scan protocols, p Ͻ 0.001). The rate of downstream testing did not differ (13.8% vs. 15.9% for axial vs. helical scan protocols, p ϭ 0.555). C O N C L U S I O N S In patients with stable and low heart rates, the prospectively ECG-triggered axial scan protocol maintained image quality but reduced radiation exposure by 69% compared with helical scanning. Axial computed tomography data acquisition should be strongly recommended in suitable patients to avoid unnecessarily high radiation exposure.
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 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 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 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) and HR differences (2.8 +/- 2.7 bpm; r = 0.49; P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 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.
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.
Academic Radiology, 2017
Abbreviations and Acronyms cCTA coronary computed tomography angiography ECG electrocardiographic DSCT dual-source computed tomography ROI region of interest BDP best diastolic phase BSP best systolic phase CNR contrast-to-noise-ratio DLP dose length product Rationale and Objectives: Despite ongoing technical refinements, coronary computed tomography angiography (cCTA) remains challenging in its diagnostic value by electrocardiographic (ECG) misregistration and motion artifacts, which commonly occur in patients with atrial fibrillation and high or irregular heart rates. The aim of this study was to evaluate the radiation dose and the number of inconclusive coronary segments at cCTA using retrospective ECG gating at 100 and 70 kV. Materials and Methods: With institutional review board approval, 154 patients (median age 54 years, 98 men) with high or irregular heart rate prospectively underwent retrospectively ECG-gated cCTA without tube current modulation on a third-generation dual-source computed tomography (DSCT) system at 70 kV (n = 103) or on a second-generation DSCT system at 100 kV (n = 51). Images were reconstructed in best diastolic phase (BDP), best systolic phase (BSP), and in all phases (APs) at 10% intervals across the R-R cycle. Objective and subjective image qualities were evaluated as well as the presence of motion artifacts with the three different reconstruction approaches. Results: The mean heart rate was 93 ± 16 bpm. The mean effective radiation dose was 4.5 mSv for 70 kV compared to 8.4 mSv for 100 kV (P < 0.05). At BDP reconstruction, 71% (n = 110) of the patients showed motion artifacts in one or more coronary segments. At BSP reconstruction, the number of patients with motion artifacts decreased to 37% (n = 57). In contrast, if images were reconstructed with the AP approach, all vessels and coronary segments were evaluable with both cCTA protocols. Conclusions: Retrospectively ECG-gated cCTA at 70 kV results in 52% decreased radiation dose. Further using the AP algorithm allowed for diagnostic evaluation of all coronary segments for stenosis, in contrast to BDP or BSP phase alone.
Objectives: We sought to determine the feasibility of using 80 kV in clinical cardiac CTA, by comparing radiation doses and image quality versus standardized 100 kV protocols. Methods: In this retrospective study, a tube potential of 80 kV was used in 40 consecutive patients (BMI 22.6 ± 2.8). 40 matched patients (BMI 23.1 ± 2.8) were scanned with a tube potential of 100 kV and served as the control group. Qualitative and quantitative image quality parameters were determined in the proximal and distal segments of the coronary arteries. Results: Similar subjective image quality scores were seen between the two protocols. The mean CNR and SNR were at 100 kV vs 80 kV (CNR 19.9 ± 6.0 vs 15.7 ± 5.5; p<0.01 and SNR 17.7 ± 5.5 vs 14.4 ± 4.9). The median radiation dose for the 80 kV protocol was significantly lower compared to the 100 kV protocol (83.0 mGy x cm [58.0-134.0] vs 193.0 mGy x cm [108.5-225.0]; p<0.01) Conclusion: A tube potential of 80 kV is feasible and results in a radia...
Journal of Clinical Imaging Science, 2013
Objectives: The objective of the following study is to evaluate the effect of reducing tube voltage from 120 to 100 kVp using prospective gating 320 row multi-detector computed tomography angiography on image quality and reduction in radiation dose. Materials and Methods: A total of 78 sequential patients were scanned with prospective electrocardiogram gating. A total of 45 patients (Group 1) with mean body mass index (BMI) 29 ± 2 and heart rate (HR) 57 ± 7 beats per minute (BPM) were scanned at 120 kVp. 33 patients (Group 2) with mean BMI 23 ± 3 and HR 58 ± 6 bpm were scanned at 100 kVp. Effective dose was calculated using dose length product and factor (k = 0.014). Quantitative assessment of image quality was calculated by measuring signal to noise ratio (SNR) and contrast to noise ratio (CNR) in the left ventricle and left main coronary artery. Two experienced cardiac radiologists using a three-point ordinal scale assessed subjectively image quality. Results: In Group 1, the medi...
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.
Reduction in Radiation Exposure in Cardiovascular CT Imaging
European Heart Journal, 2018
Aims Advances of cardiac computed tomography angiography (CTA) have been developed for dose reduction, but their efficacy in clinical practice is largely unknown. This study was designed to evaluate radiation dose exposure and utilization of dose-saving strategies for contrast-enhanced cardiac CTA in daily practice.