Electrocardiographic Triggering Research Articles

Turbo spin-echo-based enhanced acceleration-selective arterial spin labeling without electrocardiography or peripheral pulse unit triggering and contrast enhancement for lower extremity MRA

PurposeLower extremity magnetic resonance angiography (MRA) without electrocardiography (ECG) or peripheral pulse unit (PPU) triggering and contrast enhancement is beneficial for diagnosing peripheral arterial disease (PAD) while avoiding synchronization failure and nephrogenic systemic fibrosis. This study aimed to compare the diagnostic performance of turbo spin-echo-based enhanced acceleration-selective arterial spin labeling (eAccASL) (TSE-Acc) of the lower extremities with that of turbo field-echo-based eAccASL (TFE-Acc) and triggered angiography non-contrast enhanced (TRANCE). MethodsNine healthy volunteers and a patient with PAD were examined on a 3.0 Tesla magnetic resonance imaging (MRI) system. The artery-to-muscle signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) were calculated. The arterial visibility (1: poor, 4: excellent) and artifact contamination (1: severe, 4: no) were independently assessed by two radiologists. Phase-contrast MRI and digital subtraction angiography were referenced in a patient with PAD. Friedman's test and a post-hoc test according to the Bonferroni-adjusted Wilcoxon signed-rank test were used for the SIR, CNR, and visual assessment. p < 0.05 was considered statistically significant. ResultsNo significant differences in nearly all the SIRs were observed among the three MRA methods. Higher CNRs were observed with TSE-Acc than those with TFE-Acc (anterior tibial artery, p = 0.014; peroneal artery, p = 0.029; and posterior tibial artery, p = 0.014) in distal arterial segments; however, no significant differences were observed upon comparison with TRANCE (all p > 0.05). The arterial visibility scores exhibited similar trends as the CNRs. The artifact contamination scores with TSE-Acc were significantly lower (but within an acceptable level) compared to those with TFE-Acc. In the patient with PAD, the sluggish peripheral arteries were better visualized using TSE-Acc than those using TFE-Acc, and the collateral and stenosis arteries were better visualized using TSE-Acc than those using TRANCE. ConclusionPeripheral arterial visualization was better with TSE-Acc than that with TFE-Acc in lower extremity MRA without ECG or PPU triggering and contrast enhancement, which was comparable with TRANCE as the reference standard. Furthermore, TSE-Acc may propose satisfactory diagnostic performance for diagnosing PAD in patients with arrhythmia and chronic kidney disease.

Fast self-navigated wall shear stress measurements in the murine aortic arch using radial 4D-phase contrast cardiovascular magnetic resonance at 17.6\u2009T

Purpose4D flow cardiovascular magnetic resonance (CMR) and the assessment of wall shear stress (WSS) are non-invasive tools to study cardiovascular risks in vivo. Major limitations of conventional triggered methods are the long measurement times needed for high-resolution data sets and the necessity of stable electrocardiographic (ECG) triggering. In this work an ECG-free retrospectively synchronized method is presented that enables accelerated high-resolution measurements of 4D flow and WSS in the aortic arch of mice.Methods4D flow and WSS were measured in the aortic arch of 12-week-old wildtype C57BL/6 J mice (n = 7) with a radial 4D-phase-contrast (PC)-CMR sequence, which was validated in a flow phantom. Cardiac and respiratory motion signals were extracted from the radial CMR signal and were used for the reconstruction of 4D-flow data. Rigid motion correction and a first order B0 correction was used to improve the robustness of magnitude and velocity data.The aortic lumen was segmented semi-automatically. Temporally averaged and time-resolved WSS and oscillatory shear index (OSI) were calculated from the spatial velocity gradients at the lumen surface at 14 locations along the aortic arch. Reproducibility was tested in 3 animals and the influence of subsampling was investigated.ResultsVolume flow, cross-sectional areas, WSS and the OSI were determined in a measurement time of only 32 min. Longitudinal and circumferential WSS and radial stress were assessed at 14 analysis planes along the aortic arch. The average longitudinal, circumferential and radial stress values were 1.52 ± 0.29 N/m2, 0.28 ± 0.24 N/m2 and − 0.21 ± 0.19 N/m2, respectively. Good reproducibility of WSS values was observed.ConclusionThis work presents a robust measurement of 4D flow and WSS in mice without the need of ECG trigger signals. The retrospective approach provides fast flow quantification within 35 min and a flexible reconstruction framework.

Image Quality, Overall Evaluability, and Effective Radiation Dose of Coronary Computed Tomography Angiography With Prospective Electrocardiographic Triggering Plus Intracycle Motion Correction Algorithm in Patients With a Heart Rate Over 65 Beats Per Minute.

Recently, a new intracycle motion correction algorithm (MCA) was introduced to reduce motion artifacts from heart rate (HR) in coronary computed tomography angiography (cCTA). The aim of the study was to evaluate the image quality, overall evaluability, and effective radiation dose (ED) of cCTA with prospective electrocardiographic (ECG) triggering plus MCA as compared with standard protocol with retrospective ECG triggering in patients with HR≥65 bpm. One hundred consecutive patients (67±10 y) scheduled for cCTA with 65<HR<80 bpm were retrospectively analyzed. The patients were assigned to 2 groups undergoing prospective (group 1) or retrospective (group 2) triggered cCTA. The study protocol was approved by the Institutional Ethics Committee and a written informed consent was obtained from all patients. Image noise, signal to noise ratio, contrast to noise ratio, Likert image quality score (score 1, nondiagnostic; score 2, adequate; score 3, good; score 4, excellent), overall image evaluability, and ED were measured and compared between the 2 groups. Both vessel-based and patient-based analyses were evaluated. Student test or Wilcoxon test were used to evaluate differences of continuous variables, whereas the χ test was used to study differences with regard to categorical data. A P-value <0.05 was considered statistically significant. cCTA was successfully performed in all patients. In a segment-based model, group 1 compared with group 2 showed a lower rate of overall artifacts (67% vs. 83%; P<0.001) and motion artifacts (49% vs. 66%; P<0.001), resulting in a better Likert image quality score (2.83±1.03 vs. 2.37±1.02; P<0.01) and overall evaluability (85% vs. 75%; P<0.01). Group 1 showed a lower ED as compared with group 2 (3.1±1.9 vs. 11.9±3.3 mSv; P<0.01). MCA and cCTA with prospective ECG-triggering acquisition in patients with high HR improves image quality and overall evaluability compared with cCTA with standard retrospective ECG triggering.

Magnetic resonance multitasking for motion-resolved quantitative cardiovascular imaging.

Quantitative cardiovascular magnetic resonance (CMR) imaging can be used to characterize fibrosis, oedema, ischaemia, inflammation and other disease conditions. However, the need to reduce artefacts arising from body motion through a combination of electrocardiography (ECG) control, respiration control, and contrast-weighting selection makes CMR exams lengthy. Here, we show that physiological motions and other dynamic processes can be conceptualized as multiple time dimensions that can be resolved via low-rank tensor imaging, allowing for motion-resolved quantitative imaging with up to four time dimensions. This continuous-acquisition approach, which we name cardiovascular MR multitasking, captures — rather than avoids — motion, relaxation and other dynamics to efficiently perform quantitative CMR without the use of ECG triggering or breath holds. We demonstrate that CMR multitasking allows for T1 mapping, T1-T2 mapping and time-resolved T1 mapping of myocardial perfusion without ECG information and/or in free-breathing conditions. CMR multitasking may provide a foundation for the development of setup-free CMR imaging for the quantitative evaluation of cardiovascular health.

Initial Assessment of the Efficacy of Irreversible Electroporation in the Focal Treatment of Localized Renal Cell Carcinoma With Delayed-interval Kidney Tumor Resection (Irreversible Electroporation of Kidney Tumors Before Partial Nephrectomy [IRENE] Trial—An Ablate-and-Resect Pilot Study)

To assess the efficacy of irreversible electroporation (IRE) ablation of pT1a renal cell carcinoma (RCC) in the first prospective, monocentric phase 2a pilot ablate-and-resect study (Irreversible Electroporation of Kidney Tumors Before Partial Nephrectomy [IRENE] trial). It has been postulated that focal IRE can bring about complete ablation of soft-tissue tumors with protection of healthy peritumoral tissue and anatomic structures. The first 7 study patients with biopsy-proven pT1a RCC (15-39 mm) underwent IRE. Percutaneous computed tomography-guided IRE was performed with electrocardiographic triggering under general anesthesia and deep muscle paralysis with 3-6 monopolar electrodes positioned within the renal tumor. Twenty-eight days later, the tumor region was completely resected to confirm tumor destruction pathologically. Individual results for these patients are displayed, described, and discussed. Technical feasibility was attained in all patients, but electrode placement and ablation were complex, with a mean overall procedure time of 129 minutes. There were no major complications. Partial kidney resection was performed in 5 patients, and radical nephrectomy was performed in 2 patients because of central tumor location and ablation areas. Resections revealed by tumor, node, and metastasis classification of the International Union for Cancer Control 2017 no residual tumor as complete ablation in 4 cases (ypT0V0N0Pn0R0) and microscopic residual tumor cells as incomplete ablation in the other 3 cases (ypT1aV0N0Pn0R1). Renal percutaneous IRE appears to be a safe treatment for pT1a RCC but requires substantial procedural effort. Resection specimens of the ablation zone revealed a high rate of microscopic incomplete ablation 4 weeks after IRE. According to these initial study results, curative, kidney-sparing ablation of T1a RCC appears possible but needs technical improvement to ensure complete ablation.

Non‐contrast‐enhanced peripheral MR angiography using velocity‐selective excitation

To develop a new non-contrast-enhanced peripheral MR angiography that provides a high contrast angiogram without using electrocardiography triggering and saturation radiofrequency pulses. A velocity-selective excitation technique is used in conjunction with the golden-angle radial sampling scheme. The signal amplitude varies according to the velocity of the flow by the velocity-selective excitation technique. Because the arterial blood velocity varies depending on the cardiac phase, the acquired data can be classified into systolic and diastolic phase based on the signal amplitude of the artery. Two images are then reconstructed from the systolic and diastolic phase data, respectively, and an image reflecting the differences between the two images is obtained to eliminate background and vein signals. The performance of the proposed method was compared with the quiescent-interval single shot (QISS) in eight healthy subjects and an elderly subject. The proposed method generated fewer residual venous and background signals than the QISS. Furthermore, the maximum intensity projection images, the relative contrast, and the apparent contrast-to-noise ratio results showed that the proposed method produced a better contrast than the QISS. The proposed non-contrast-enhanced peripheral MR angiography technique can provide a high contrast angiogram without the use of electrocardiography triggering and saturation radiofrequency pulses. Magn Reson Med 79:779-788, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Combined Electrocardiography- and Respiratory-Triggered CT of the Lung to Reduce Respiratory Misregistration Artifacts between Imaging Slabs in Free-Breathing Children: Initial Experience.

ObjectiveCardiac and respiratory motion artifacts degrade the image quality of lung CT in free-breathing children. The aim of this study was to evaluate the effect of combined electrocardiography (ECG) and respiratory triggering on respiratory misregistration artifacts on lung CT in free-breathing children.Materials and MethodsIn total, 15 children (median age 19 months, range 6 months–8 years; 7 boys), who underwent free-breathing ECG-triggered lung CT with and without respiratory-triggering were included. A pressure-sensing belt of a respiratory gating system was used to obtain the respiratory signal. The degree of respiratory misregistration artifacts between imaging slabs was graded on a 4-point scale (1, excellent image quality) on coronal and sagittal images and compared between ECG-triggered lung CT studies with and without respiratory triggering. A p value < 0.05 was considered significant.ResultsLung CT with combined ECG and respiratory triggering showed significantly less respiratory misregistration artifacts than lung CT with ECG triggering only (1.1 ± 0.4 vs. 2.2 ± 1.0, p = 0.003).ConclusionAdditional respiratory-triggering reduces respiratory misregistration artifacts on ECG-triggered lung CT in free-breathing children.

The Effect of Heart Rate on Exposure Window and Best Phase for Stress Perfusion Computed Tomography

The aim of this study is to evaluate the effect of heart rate on exposure window, best phase, and image quality for stress computed tomography perfusion (CTP) in the CORE320 study. The CTP data sets were analyzed to determine the best phase for perfusion analysis. A predefined exposure window covering 75% to 95% of the R-R cycle was used. Of the 368 patients included in the analysis, 93% received oral β blockade before the rest scan. The median heart rate during the stress acquisition was 69 bpm (interquartile range [IQR], 60-77). The median best phase was 81% (IQR, 76-90), and length of exposure window was 22% (IQR, 19-24). The best phase was significantly later in the cardiac cycle with higher heart rates (P < 0.001), and higher heart rates resulted in a small, but higher number of poor quality scans (6%, P < 0.001). The median effective dose of the stress scan was 5.3 mSv (IQR, 3.8-6.1). Stress myocardial CTP imaging can be performed using prospective electrocardiography triggering, an exposure window of 75% to 95%, and β-blockade resulting in good or excellent image quality in the majority (80%) of patients while maintaining a low effective radiation dose.

Accuracy and effectiveness of self-gating signals in free-breathing three-dimensional cardiac cine magnetic resonance imaging**Project supported by the National Natural Science Foundation of China (Grant Nos. 81501463, 61471349, 81671853, 81571669, and 61671026), the National High Technology Research and Development Program of China (Grant No. 2015AA043203), the Natural Science Foundation of Beijing, China (Grant No. 7162112), Guangdong Innovative Research Team Program of

Conventional multiple breath-hold two-dimensional (2D) balanced steady-state free precession (SSFP) presents many difficulties in cardiac cine magnetic resonance imaging (MRI). Recently, a self-gated free-breathing three-dimensional (3D) SSFP technique has been proposed as an alternative in many studies. However, the accuracy and effectiveness of self-gating signals have been barely studied before. Since self-gating signals are crucially important in image reconstruction, a systematic study of self-gating signals and comparison with external monitored signals are needed.Previously developed self-gated free-breathing 3D SSFP techniques are used on twenty-eight healthy volunteers. Both electrocardiographic (ECG) and respiratory bellow signals are also acquired during the scan as external signals. Self-gating signal and external signal are compared by trigger and gating window. Gating window is proposed to evaluate the accuracy and effectiveness of respiratory self-gating signal. Relative deviation of the trigger and root-mean-square-deviation of the cycle duration are calculated. A two-tailed paired t-test is used to identify the difference between self-gating and external signals. A Wilcoxon signed rank test is used to identify the difference between peak and valley self-gating triggers.The results demonstrate an excellent correlation (P = 0, R > 0.99) between self-gating and external triggers. Wilcoxon signed rank test shows that there is no significant difference between peak and valley self-gating triggers for both cardiac (H = 0, P > 0.10) and respiratory (H = 0, P > 0.44) motions. The difference between self-gating and externally monitored signals is not significant (two-tailed paired-sample t-test: H = 0, P > 0.90).The self-gating signals could demonstrate cardiac and respiratory motion accurately and effectively as ECG and respiratory bellow. The difference between the two methods is not significant and can be explained. Furthermore, few ECG trigger errors appear in some subjects while these errors are not found in self-gating signals.

Image quality of ct angiography using model-based iterative reconstruction in infants with congenital heart disease: Comparison with filtered back projection and hybrid iterative reconstruction

PurposeTo compare the image quality, rate of coronary artery visualization and diagnostic accuracy of 256-slice multi-detector computed tomography angiography (CTA) with prospective electrocardiographic (ECG) triggering at a tube voltage of 80kVp between 3 reconstruction algorithms (filtered back projection (FBP), hybrid iterative reconstruction (iDose4) and iterative model reconstruction (IMR)) in infants with congenital heart disease (CHD). MethodsFifty-one infants with CHD who underwent cardiac CTA in our institution between December 2014 and March 2015 were included. The effective radiation doses were calculated. Imaging data were reconstructed using the FBP, iDose4 and IMR algorithms. Parameters of objective image quality (noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)); subjective image quality (overall image quality, image noise and margin sharpness); coronary artery visibility; and diagnostic accuracy for the three algorithms were measured and compared. ResultsThe mean effective radiation dose was 0.61±0.32 mSv. Compared to FBP and iDose4, IMR yielded significantly lower noise (P<0.01), higher SNR and CNR values (P<0.01), and a greater subjective image quality score (P<0.01). The total number of coronary segments visualized was significantly higher for both iDose4 and IMR than for FBP (P=0.002 and P=0.025, respectively), but there was no significant difference in this parameter between iDose4 and IMR (P=0.397). There was no significant difference in the diagnostic accuracy between the FBP, iDose4 and IMR algorithms (χ2=0.343, P=0.842). ConclusionsFor infants with CHD undergoing cardiac CTA, the IMR reconstruction algorithm provided significantly increased objective and subjective image quality compared with the FBP and iDose4 algorithms. However, IMR did not improve the diagnostic accuracy or coronary artery visualization compared with iDose4.

Is ECG triggering for motion artefact reduction in dual-source CT angiography of the ascending aorta still required with high-pitch scanning? The role of ECG-gating in high-pitch dual-source CT of the ascending aorta.

To compare electrocardiographic (ECG)-triggered high-pitch (HP) dual-source CT angiography (CTA) with non-ECG-triggered HP CTA of the aorta, particularly the ascending aorta, with regard to image quality, motion artefacts, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and radiation dose. 59 consecutive patients who had been referred for CTA for known or suspected aortic disease, previous aortic intervention or planned transapical or transfemoral aortic valve implantation were prospectively included. Patients underwent CTAs with HP, using a dual-source CTA system, with [control group (Group A); n = 30] or without (Group B; n = 29) ECG triggering after randomization. For evaluation, image quality and a motion artefact score (MAS) were assessed in a blinded fashion at different predefined anatomic regions. CNR and SNR were measured at the same levels. Radiation dose estimates and contrast enhancement were compared between the two groups. There were no significant differences for image quality and MAS. The intra-arterial contrast resolution was significantly higher at the level of the aortic arch and descending aorta in the non-triggered group (CNR values, p = 0.002-0.018). No significant differences in the radiation dose were found. Non-triggered HP dual-source CTA provided comparable results with regard to image quality, MAS, CNR, SNR and radiation doses compared with ECG-triggered HP CTA. Therefore, ECG triggering of the ascending aorta might be obviated when HP scanning is available. HP dual-source CTA might obviate ECG triggering in the ascending aorta. Non-triggered HP CTA of the ascending aorta provides an excellent image quality.

Effects of arterial blood flow on walls of the abdominal aorta: distributions of wall shear stress and oscillatory shear index determined by phase-contrast magnetic resonance imaging.

Although abdominal aortic aneurysms (AAAs) occur mostly inferior to the renal artery, the mechanism of the development of AAA in relation to its specific location is not yet clearly understood. The objective of this study was to evaluate the hypothesis that even healthy volunteers may manifest specific flow characteristics of blood flow and alter wall shear or oscillatory shear stress in the areas where AAAs commonly develop. Eight healthy male volunteers were enrolled in this prospective study, aged from 24 to 27. Phase-contrast magnetic resonance imaging (MRI) was performed with electrocardiographic triggering. Flow-sensitive four-dimensional MR imaging of the abdominal aorta, with three-directional velocity encoding, including simple morphological image acquisition, was performed. Information on specific locations on the aortic wall was applied to the flow encodes to calculate wall shear stress (WSS) and oscillatory shear index (OSI). While time-framed WSS showed the highest peak of 1.14±0.25Pa in the juxtaposition of the renal artery, the WSS plateaued to 0.61Pa at the anterior wall of the abdominal aorta. The OSI peaked distal to the renal arteries at the posterior wall of the abdominal aorta of 0.249±0.148, and was constantly elevated in the whole abdominal aorta at more than 0.14. All subjects were found to have elevated OSI in regions where AAAs commonly occur. These findings indicate that areas of constant peaked oscillatory shear stress in the infra-renal aorta may be one of the factors that lead to morphological changes over time, even in healthy individuals.

Cardiac fusion and complex congenital cardiac defects in thoracopagus twins: diagnostic value of cardiac CT

Most thoracopagus twins present with cardiac fusion and associated congenital cardiac defects, and assessment of this anatomy is of critical importance in determining patient care and outcome. Cardiac CT with electrocardiographic triggering provides an accurate and quick morphological assessment of both intracardiac and extracardiac structures in newborns, making it the best imaging modality to assess thoracopagus twins during the neonatal period. In this case report, we highlight the diagnostic value of cardiac CT in thoracopagus twins with an interatrial channel and complex congenital cardiac defects.

Technical note: Electrocardiogram electrode repositioning for 320-row coronary CT angiography in patients with regular and recurrent premature ventricular contractions

Arrhythmias can compromise image quality and increase radiation exposure during coronary CT angiography (CTA). However, premature ventricular contractions (PVCs) can occur in a predictable recurrent and regular pattern (ie, bigeminy, trigeminy, quadrigeminy) with post-PVC compensatory pauses. Electrocardiographic (ECG) electrode repositioning can achieve relative amplification of the R waves of PVCs compared with R waves of sinus beats. This technical note describes how simple ECG electrode repositioning, combined with an absolute-delay strategy, facilitated selective R waves of PVC ECG triggering of image acquisition in 6 patients with PVC bigeminy or quadrigeminy at the time of 320-row coronary CTA. All 6 studies were single heartbeat acquisition scans with excellent image quality and a median effective radiation dose of 2.9 mSv (interquartile range, 2.1–3.8 mSv). Standard ECG electrode positions used for 2 patients with PVC bigeminy undergoing coronary CTA were associated with an acquisition over 2 heartbeats and effective radiation doses of 6.8 and 10.3 mSv, respectively. In conclusion, ECG electrode repositioning combined with an absolute-delay strategy for regularly recurring PVCs, such as ventricular bigeminy, facilitates high image quality and lower radiation dose during coronary CTA. This simple and straightforward technique can be considered for all patients with regular and recurrent PVCs undergoing coronary CTA.

Emerging and Evolving Roles for CT in Screening for Coronary Heart Disease

Coronary heart disease (CHD) is highly prevalent and is the primary cause of death for both men and women, worldwide. Because the disease develops over many years, there are opportunities to intervene and alter the course of CHD, assuming that there are reliable means for determining which individuals with coronary atherosclerosis will develop symptomatic CHD. CT provides 2 distinct means for coronary artery disease assessment--coronary artery calcium (CAC) measurement using noncontrast CT and coronary CT angiography (cCTA). The recent refinement of electrocardiographic triggering and gating with CT has enabled these techniques to be performed with greater reliability and substantially lower radiation exposure. This has led to widening availability of these diagnostic techniques and rapid expansion of our understanding of their potential clinical use. Within the context of CHD, 2 applications are particularly compelling--risk stratification of asymptomatic individuals with the intent of targeting therapy to prevent CHD and as gatekeeper to cardiac catheterization to minimize unnecessary invasive diagnostic coronary procedures. This review highlights key insights from recent investigations of CHD development and CT application toward the management of individuals at risk of developing or suspected of having CHD.

Coronary computed tomography angiography with prospective electrocardiography triggering: a systematic review of image quality and radiation dose

The purpose of this study was to perform a systematic review of the diagnostic accuracy, image quality and radiation dose of prospective electrocardiography (ECG)-triggered coronary computed tomography angiography (CCTA). We searched databases containing studies of CCTA that used prospective ECG-triggering between 2008 and 2011. The effective dose and image quality reported in each study were analysed and compared between the types of multislice CT scanners. We identified 23 studies through this search, with mean assessable coronary segments and effective dose at 96.8% (95% confidence level [CI] 83%, 100%) and 3.6 mSv (95% CI 2.9, 4.3 mSv), respectively. Both quantitative and qualitative assessments of image quality indicated that image quality was achieved in studies using prospective ECG-triggered CCTA, regardless of the type of CT scanners. The pooled estimates of diagnostic values were more than 90% for patient-, vessel- and segment-based assessments. Prospective ECG-triggered CCTA results in high diagnostic accuracy and image quality, with a significantly low radiation dose.

Coronary imaging techniques with emphasis on CT and MRI

Coronary artery imaging in children is challenging, with high demands both on temporal and spatial resolution due to high heart rates and smaller anatomy. Although invasive conventional coronary angiography remains the benchmark technique, over the past 10 years, CT and MRI have emerged in the field of coronary imaging. The choice of hardware is important. For CT, the minimum requirement is a 64-channel scanner. The temporal resolution of the scanner is most important for optimising image quality and minimising radiation dose. Manufacturers have developed several modes of electrocardiographic (ECG) triggering to facilitate dose reduction. Recent technical advances have opened new possibilities in MRI coronary imaging. As a non-ionising radiation technique, MRI is of great interest in paediatric imaging. It is currently recommended in centres with appropriate expertise for the screening of patients with suspected congenital coronary anomalies. However, MRI is still not feasible in infants. This review describes and discusses the technical requirements and the pros and cons of all three techniques.

Self-gated PROPELLER-encoded cine cardiac imaging

This study uses the k-space center over-sampling property of PROPELLER encoding to detect cardiac and respiratory motion using raw k-space data. Using the motion information, cine cardiac imaging is self-gated. The data acquisition process requires neither electrocardiography triggering nor patient breath-holding. Using physiology motion information, this post-processing method rearranges the k-space data into groups corresponding to cardiac and respiratory phases. The PROPELLER blades of the same groups are combined to produce cine high-resolution images. This approach reduces the potential discrepancy of the k-space data and the motion-related artifacts in the reconstructed image because all blades in a group are acquired at consistent cardiac and respiratory phases. The study concludes that self-gated cine cardiac imaging is feasible using PROPELLER encoding. It is a potentially practical tool for cine cardiac imaging.

Diagnostic Performance of High-Definition Coronary Computed Tomography Angiography Performed With Multiple Radiation Dose Reduction Strategies

Background Numerous radiation dose reduction measures have been proposed for coronary computed tomographic angiography (CCTA). Although these techniques allow for imaging with reduced radiation, it is unknown whether diagnostic performance is maintained. A new high-definition CCTA (HD-CCTA) allows higher spatial resolution, reduced image noise, and lower radiation doses. Objectives The aim of this study was to determine the diagnostic performance of HD-CCTA, in combination with multiple radiation dose reduction strategies, for the detection of obstructive coronary artery disease. Methods Consecutive patients (N = 43, aged 60 ± 10 years, 83% male) with chest pain and referred for quantitative coronary angiography (QCA) underwent HD-CCTA with radiation dose reduction measures, including prospective electrocardiographic triggering, reduction of additional tube on-time, and minimization of tube voltage and current. Intraluminal diameter stenosis ≥ 50% was considered significant. QCA served as the reference standard. The area under the receiver-operating-characteristic curve (AUC) was used to evaluate diagnostic accuracy. Results All scans demonstrated diagnostic image quality, with 99% (543/548) of included coronary segments interpretable by HD-CCTA. Median effective radiation dose was 2.8 mSv (interquartile range, 1.3-3.9). The AUC for the per-patient assessment for stenosis ≥ 50% was 0.90 (95% confidence interval [CI], 0.77-0.96), with sensitivity of 95% (95% CI, 85%-100%), specificity of 79% (95% CI, 63%-95%), positive predictive value of 78% (95% CI, 61%-95%), and negative predictive value of 95% (95% CI, 85%-100%). Conclusions Compared with QCA, HD-CCTA with multiple dose reduction measures resulted in low radiation doses and high diagnostic accuracy to detect and exclude obstructive coronary artery disease.

Diagnostic accuracy of dual-source CT coronary angiography with prospective electrocardiography triggering in patients with higher heart rate

Objective To evaluate the diagnostic accuracy of dual-source CT(DSCT)prospective ECG-triggering coronary angiography in patients with different heart rate(HR).Methods One hundred and three patients with suspected coronary artery disease underwent DSCT prospective ECG-triggered coronary angiography and invasive coronary angiography(ICA).The patients were grouped by HR during CT scans:low HR( 70 bpm,n=33).Image quality was scored using a 4-point scale.The sensitivity and specificity of DSCT in detecting≥50%stenosis were compared among subgroups where ICA was the gold standard.The differences were compared by using the X2 test of contingency on a per-segment and per-vessel basis.Results Image quality of 1580 coronary artery segments in 1648(95.9%)met the requirements for diagnosis.The image quality scores were(3.1±0.3),(3.1±0.3)and(3.0±0.4)point for subgroups(X2=2.80,P>0.05).Sensitivity and specificity were 82.8%(77/93)and 98.4%(428/435),88.3%(91/103)and 98.7%(442/448),and 80.3%(57/71)and 98.6%(424/430)for different subgroups(X2 were 0.69 and 0.13,all P>0.05).The overall area under the receiver operating characteristic(ROC)curve was 0.94(95%CI=0.92-0.96).The average effective radiation dose was(3.60±1.60)mSv.Conclusion DSCT coronary angiography with prospective ECG-triggering could be used for patients with high HR.And the diagnostic accuracy was not statistical significant between the patients with low HR and patients with medium to high HR. Key words: Heart rate; Coronary angiography; Tomography, X-ray computed; Diagnosis