Prospective versus retrospective ECG gating for 320-detector CT of the coronary arteries: comparison of image quality and patient radiation dose (original) (raw)

Related papers

Prospective ECG triggering versus low-dose retrospective ECG-gated 128-channel CT coronary angiography: comparison of image quality and radiation dose

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.

Assessment of image quality and radiation dose in prospective ECG-triggered coronary CT angiography compared with retrospective ECG-gated coronary CT angiography

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.

Initial evaluation of coronary images from 320-detector row computed tomography

The International Journal of Cardiovascular Imaging, 2008

To evaluate image quality and contrast opacification from coronary images acquired from 320-detector row computed tomography (CT). Patient dose is estimated for prospective and retrospective ECG-gating; initial correlation between 320-slice CT and coronary catheterization is illustrated. Retrospective image evaluation from forty consecutive patients included subjective assessment of image quality and contrast opacification (80 ml iopamidol 370 mg I/ml followed by 40 ml saline). Region of interest opacification measurements at the ostium and at 2.5 mm diameter were used to determine the gradient of contrast opacification (defined as the proximal minus distal HU measurements) in coronary arteries imaged in a single heartbeat. Estimated effective dose was compared for prospective versus retrospective ECG-gating, two body mass index categories (30 kg/m(2) cutoff), and single versus two heartbeat acquisition. When available, CT findings were correlated with those from coronary catheterization. Over 89% of arterial segments (15 segment model) had excellent image quality. The most common reason for image degradation was cardiac motion. One segment in one patient was considered unevaluable. Contrast opacification was almost universally considered excellent. The mean Hounsfield units (HU) was greater than 350; the coronary contrast opacification gradient was 30-50 HU. Patient doses were greater for retrospective ECG-gating, larger patients, and those imaged with two heartbeats. For the most common (n=25) protocol (120 kV, 400 mA, prospective ECG-gating, 60-100% phase window, 16 cm craniocaudal coverage, single heartbeat), the mean dose was 6.8+/-1.4 mSv. All CT findings were confirmed in the four patients who underwent coronary catheterization. Initial 320-detector row coronary CT images have consistently excellent quality and iodinated contrast opacification. These patients were scanned with conservative protocols with respect to iodine load, prospective ECG-gating phase window, and craniocaudal coverage. Future work will focus on lowering contrast and radiation dose while maintaining image quality.

Prospective Coronary CT Angiography 128-MDCT Versus Retrospective 64-MDCT: Improved Image Quality and Reduced Radiation Dose

Heart, Lung and Circulation, 2011

New technologies for computed tomography coronary arteries imaging aim to reduce the radiation dose whilst maintaining image quality. The purpose of our study was to compare radiation dose and image quality parameters of Coronary Computed Tomography Angiography (CCTA) performed with retrospective 64-MDCT and prospective 128-MDCT. Patients and Methods: A series of 77 consecutive patients were first randomised to either retrospective 64-MDCT (n = 37) or prospective 128-MDCT (n = 40) for CCTA. All patients in the retrospective 64-MDCT group were scanned with tube current modulation as strategy for reduction dose. Data regarding acquisition time and radiation dose were recorded. Two blinded radiologists independently assessed image quality of all coronary segments by using a four-point scale (1, excellent; 4, poor). Discrepancies were settled by consensus. Results: No significant differences were found regarding sex, age, body weight and heart rate. CTTA effective radiation dose was 2.1 ± 0.9 vs. 8.2 ± 4 mSv in prospective and retrospective ECG-gating MDCT groups, respectively. Mean image quality score was 2.2 ± 0.9 for prospective 128-MDCT group and 1.4 ± 0.7 points for retrospective 64-MDCT representing a mean difference of 0.8 points (CI: 0.9 to 0.7). Conclusion: In selected patients, CCTA using a 128-MDCT with prospective ECG-gating provides higher image quality with significant lower radiation dose when compared to 64-MDCT using retrospective ECG-gating.

Superior CT coronary angiography image quality at lower radiation exposure with second generation 320-detector row CT in patients with elevated heart rate: a comparison with first generation 320-detector row CT

Cardiovascular diagnosis and therapy, 2014

This study aims to compare the image quality of second generation versus first generation 320-computed tomography coronary angiography (CTCA) in patients with heart rate ≥65 bpm as it has not been specifically reported. Consecutive patients who underwent CTCA using second-generation-320-detector-row-CT were prospectively enrolled. A total of 50 patients with elevated (≥65 bpm) heart rate and 50 patients with controlled (<65 bpm) heart rate were included. Age and gender matched patients who were scanned with the first-generation-320-detector-row-CT were retrospectively identified. Image quality in each coronary artery segment was assessed by two blinded CT angiographers using the five-point Likert scale. In the elevated heart rate cohorts, while there was no significant difference in heart rate during scan-acquisition (66 vs. 69 bpm, P=0.308), or body mass index (28.5 vs. 29.6, P=0.464), the second generation scanner was associated with better image quality (3.94±0.6 vs. 3.45±0.8,...

Feasibility of low-dose coronary CT angiography: first experience with prospective ECG-gating

European Heart Journal, 2007

Aims To determine the feasibility of prospective electrocardiogram (ECG)-gating to achieve low-dose computed tomography coronary angiography (CTCA). Methods and results Forty-one consecutive patients with suspected (n ¼ 35) or known coronary artery disease (n ¼ 6) underwent 64-slice CTCA using prospective ECG-gating. Individual radiation dose exposure was estimated from the dose-length product. Two independent readers semi-quantitatively assessed the overall image quality on a five-point scale and measured vessel attenuation in each coronary segment. One patient was excluded for atrial fibrillation. Mean effective radiation dose was 2.1 + 0.6 mSv (range, 1.1-3.0 mSv). Image quality was inversely related to heart rate (HR) (57.3 + 6.2, range 39-66 b.p.m.; r ¼ 0.58, P , 0.001), vessel attenuation (346 + 104, range 110-780 HU; r ¼ 0.56, P , 0.001), and body mass index (26.1 + 4.0, range 19.1-36.3 kg/m 2 ; r ¼ 0.45, P , 0.001), but not to HR variability (1.5 + 1.0, range 0.2-5.1 b.p.m.; r ¼ 0.28, P ¼ 0.069). Non-diagnostic CTCA image quality was found in 5.0% of coronary segments. However, below a HR of 63 b.p.m. (n ¼ 28), as determined by receiver operator characteristic curve, only 1.1% of coronary segments were non-diagnostic compared with 14.8% with HR of .63 b.p.m. (P , 0.001). Conclusion This first experience documents the feasibility of prospective ECG-gating for CTCA with diagnostic image quality at a low radiation dose (1.1-3.0 mSv), favouring HR ,63 b.p.m.

Prospective versus retrospective ECG-gated multislice CT coronary angiography: A systematic review of radiation dose and diagnostic accuracy

European Journal of Radiology, 2012

Purpose: To perform a systematic review of the radiation dose and diagnostic accuracy of prospective versus retrospective ECG-gated multislice CT coronary angiography. Materials and methods: A search of Pubmed/Medline and Sciencedirect databases for English literature was performed to identify studies comparing prospective and retrospective ECG-gated multislice CT angiography in the diagnosis of coronary artery disease. Effective dose, dose length product, image quality and diagnostic value were compared between two groups of studies. Results: 22 studies were included for analysis. The mean effective dose of prospective ECG-gated scans was 4.5 mSv (95% CI: 3.6, 5.3 mSv), which is significantly lower than that of retrospective scans, which is 13.8 mSv (95% CI: 11.5, 16.0 mSv) (p < 0.001). The mean dose length product was 225 mGy cm (95% CI: 188, 262 mGy cm) and 822 mGy cm (95% CI: 630, 1013 mGy cm) for the prospective and retrospective ECG-gated scans, respectively, indicating a statistically significant difference between these two protocols (p < 0.0001). The mean sensitivity and specificity of multislice CT angiography in the diagnosis of coronary artery disease was 97.7% (95% CI: 93.7%, 100%) and 92.1% (95% CI: 87.2%, 97%) for prospective ECGgated scans; 95.2% (95% CI: 91%, 99.5%) and 94.4% (95% CI: 88.5%, 100%) for retrospective ECG-gated scans, respectively, with no significant difference for sensitivity but significant difference for specificity (p = 0.047). Conclusion: Multislice CT coronary angiography with prospective ECG-gating leads to a significant reduction of radiation dose when compared to that of retrospective ECG-gating, while offering comparable image quality and diagnostic value.

Coronary CT angiography with single-source and dual-source CT: Comparison of image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated protocols

International Journal of Cardiology, 2013

Background: This study is conducted to investigate and compare image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated coronary CT angiography (CCTA) with use of single-source CT (SSCT) and dual-source CT (DSCT). Methods: A total of 209 patients who underwent CCTA with suspected coronary artery disease scanned with SSCT (n=95) and DSCT (n=114) scanners using prospective ECGtriggered and retrospective ECG-gated protocols were recruited from two institutions. The image was assessed by two experienced observers, while quantitative assessment was performed by measuring the image noise, the signal-to-noise ratio (SNR) and the contrast-tonoise ratio (CNR). Effective dose was calculated using the latest published conversion coefficient factor. Results: A total of 2,087 out of 2,880 coronary artery segments were assessable, with 98.0% classified as of sufficient and 2.0% as of insufficient image quality for clinical diagnosis. There was no significant difference in overall image quality between prospective ECGtriggered and retrospective gated protocols, whether it was performed with DSCT or SSCT scanners. Prospective ECG-triggered protocol was compared in terms of radiation dose calculation between DSCT (6.5 ± 2.9 mSv) and SSCT (6.2 ± 1.0 mSv) scanners and no significant difference was noted (p=0.99). However, the effective dose was significantly lower with DSCT (18.2 ± 8.3 mSv) than with SSCT (28.3 ± 7.0 mSv) in the retrospective gated protocol. Conclusions: Prospective ECG-triggered CCTA reduces radiation dose significantly compared to retrospective ECG-gated CCTA, while maintaining good image quality.

Radiation dose in coronary CT angiography associated with prospective ECG-triggering technique: comparisons with different CT generations

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.