Retrospective ECG-gated CT Angiography Research Articles

Detection of the intimal tear in aortic dissection and ulcer-like projection in intramural hematoma: usefulness of full-phase retrospective ECG-gated CT angiography

PurposeTo compare the accuracy of non-electrocardiogram (ECG)-gated CT angiography (CTA), single-diastolic-phase ECG-gated CTA, and full-phase ECG-gated CTA in detecting the intimal tear (IT) in aortic dissection (AD) and ulcer-like projection (ULP) in intramural hematoma (IMH).Materials and methodsA total of 81 consecutive patients with AD and IMH of the thoracic aorta were included in this single-center retrospective study. Non-ECG-gated CTA, single-diastolic-phase ECG-gated CTA, and full-phase ECG-gated CTA were used to detect the presence of the IT and ULP in thoracic aortic regions including the ascending aorta, aortic arch, and proximal and distal descending aorta.ResultsThe accuracy of detecting the IT and ULP was significantly greater using full-phase ECG-gated CTA (88% [95% CI: 100%, 75%]) than non-ECG-gated CTA (72% [95% CI: 90%, 54%], P = 0.001) and single-diastolic-phase ECG-gated CTA (76% [95% CI: 93%, 60%], P = 0.008).ConclusionFull-phase ECG-gated CTA is more accurate in detecting the IT in AD and ULP in IMH, than non-ECG-gated CTA and single-diastolic-phase ECG-gated CTA.

Impact of the Intima Dynamic Motion in Type B Acute Aortic Dissection on Renal Injury: Quantificationally Assessed by Dose-Regulated Retrospective ECG-Gated Dual-Source CT Angiography

Little is known about the influence of intima dynamic motion on organ ischemia and related outcomes. The purpose of this study is to quantitatively evaluate intima oscillation by CT angiography (CTA), determine its impact on acute kidney injury (AKI) in patients with type B acute aortic dissection (TB-AAD) before thoracic endovascular aortic repair (TEVAR), and further analyze its association with early adverse events postoperatively. Totally, 108 patients with TB-AAD who underwent retrospective ECG-gated CTA and received TEVAR were enrolled. Patients were divided into AKI and non-AKI groups. Area of the true lumen (TLA) was computed at R-R intervals at the upper level of kidney vessel origin every 5% step from 0% to 95%. Additionally, other morphologic parameters that have been identified as risk predictors for adverse events in uncomplicated TB-AAD were evaluated. Forty-three (39.8%) patients were sorted into the AKI group. Patients with AKI exhibited a larger value for the relative change of TLA (Crel-TLA) than patients in the non-AKI group (p < 0.001), as well as a larger maximum diameter of the descending aorta (p = 0.023) and the primary entry tear (p = 0.012). Crel-TLA and elevated systolic blood pressure were independent predictors of AKI. Patients with Crel-TLA ≥ 42.6% were associated with a high incidence of renal ischemia before TEVAR and early adverse events postoperatively (all p < 0.001). Intima dynamic motion, as quantitatively evaluated by CTA, has a significant influence on renal injury before and after the aortic intervention, as well as other adverse events, which might guide clinical therapy in high-risk patients.

Left Atrial Mapping in Patients with Atrial Fibrillation: A Comparison Study of Image Quality and Radiation Dose Between High-Pitch Spiral CT Angiography and Retrospective ECG-Gated CT Angiography

Left Atrial Mapping in Patients with Atrial Fibrillation: A Comparison Study of Image Quality and Radiation Dose Between High-Pitch Spiral CT Angiography and Retrospective ECG-Gated CT Angiography

Abdominal Aortic Intimal Flap Motion Characterization in Acute Aortic Dissection: Assessed with Retrospective ECG-Gated Thoracoabdominal Aorta Dual-Source CT Angiography

ObjectivesTo evaluate the feasibility of dose-modulated retrospective ECG-gated thoracoabdominal aorta CT angiography (CTA) assessing abdominal aortic intimal flap motion and investigate the motion characteristics of intimal flap in acute aortic dissection (AAD).Materials and Methods49 patients who had thoracoabdominal aorta retrospective ECG-gated CTA scan were enrolled. 20 datasets were reconstructed in 5% steps between 0 and 95% of the R-R interval in each case. The aortic intimal flap motion was assessed by measuring the short axis diameters of the true lumen and false lumen 2 cm above of celiac trunk ostium in different R-R intervals. Intimal flap motion and configuration was assessed by two independent observers.ResultsIn these 49 patients, 37 had AAD, 7 had intramural hematoma, and 5 had negative result for acute aortic disorder. 620 datasets of 31 patients who showed double lumens in abdominal aorta were enrolled in evaluating intimal flap motion. The maximum and minimum true lumen diameter were 12.2±4.1 mm (range 2.6∼17.4) and 6.7±4.1 mm (range 0∼15.3) respectively. The range of intimal flap motion in all patients was 5.5±2.6 mm (range 1.8∼10.2). The extent of maximum true lumen diameter decreased during a cardiac cycle was 49.5%±23.5% (range 12%∼100%). The maximum motion phase of true lumen diameter was in systolic phase (5%∼40% of R-R interval). Maximum and minimum intimal flap motion was at 15% and 75% of the R-R interval respectively. Intimal flap configuration had correlation with the phase of cardiac cycle.ConclusionsAbdominal intimal flap position and configuration varied greatly during a cardiac cycle. Retrospective ECG-gated thoracoabdominal aorta CTA can reflect the actual status of the true lumen and provide more information about true lumen collapse. This information may be helpful to diagnosis and differential diagnosis of dynamic abstraction.

Application of prospectively electrocardiograph-gated 128-slice spiral CT angiography in children with complex congenital heart disease

Objective To evaluate the prospective electrocardiograph (ECG) -gated 128-slice spiral CT angiography in the diagnosis of complex congenital heart disease and airway abnormality in children. Methods Eighty children with congenital heart disease received prospective (n=40) or retrospective ECG-gated 128-slice spiral CT angiography (n=40).All of the patients underwent ultrasound cardiogram (UCG) within one week before CTA exmination.The image quality and the effective radiation dose were statistically analyzed using independent samples t test andχ2test.The surgical results were taken as the diagnostic standards,and the preoperative prospective and retrospective CT angiography data were compared with UCG results usingχ2test. Results The effective dose of prospective ECG-gated CT angiography[ (1.00±0.26) mSv] was reduced by 86% as compared with the retrospective ECG-gated CT angiography[ (7.37±0.52) mSv] (t=69.296,P 0.05).The definitive diagnosis of extracardiac vascular anomalies was made in 98.3% (59/60) of patients by using prospective and retrospective ECG-gated CT angiography,which were significantly superior to UCG results[ (76.7% (46/60),76.7% (45/59),respectively] (χ2=13.144,12.644,P 0.05).The definitive diagnosis of the cardiac/large-vessel malformations was made in 100% of the patients by both prospective and retrospective ECG-gated CT angiography,and there was no significant difference between 128-slice spiral CT angiography results and UCG results[97.2% (35/36),97.3% (36/37),respectively] (χ2=1.014,0.001,P>0.05).In the cardiac malformations,the definitive diagnosis by prospective and retrospective ECG-gated CT angiography was 88.7% (47/53) and 92.5% (49/53),and there was no significant difference between 128-slice spiral CT angiography results and UCG results[98.1% (52/53),98.1% (52/53),respectively] (χ2=3.824,1.889,P>0.05),and no significant difference in the definitive diagnosis was observed between prospective and retrospective ECG-gated CT angiography (χ2=0.442,P>0.05).In addition,the 128-slice spiral CT angiography detected airway abnormality in 9 cases who underwent prospective or retrospective ECG-gated CT angiography. Conclusion The prospective ECG-gated 128-slice spiral CT angiography exhibits great application value in the preoperative diagnosis of complex congenital heart disease,which helps to develop surgical program and evaluate surgical risks. Key words: Heart defects,congenital; Tomography,X-ray computed; Child; Infant; Radiation dosage

Radiation Exposure Associated with Preoperative Multidetector Computed Tomography of Pulmonary Vein Isolation

Background: Multidetector computed tomography (MDCT) visualization of the pulmonary veins (PV) and left atrium provides the necessary anatomic information for successful left atrial ablation and PV isolation. However, the potential risks due to exposure to ionizing radiation associated with MDCT have raised concerns. Objectives: The purpose of this study was to compare radiation exposure between prospective and retrospective ECG-gated CT angiography (hereafter, prospective CTA, retrospective CTA). Methods: The 64-slice MDCT (Discovery CT 750HD, GE Healthcare) was performed 78 consecutive patients. Twenty-eight patients were analyzed by prospective CTA using step-and-shoot protocol, and 50 patients were analyzed by retrospective CTA. Results: Mean (±SD) effective radiation exposure in the prospective CTA group was 2.2±0.8 mSv compared to 15.4±5.9 mSv in the retrospective CTA group (p<0.001). Conclusion: In preoperative evaluation of PV isolation, prospective CTA can reduce radiation exposure than retrospective CTA.

Prospective ECG-triggered axial CT at 140-kV tube voltage improves coronary in-stent restenosis visibility at a lower radiation dose compared with conventional retrospective ECG-gated helical CT

The purpose of this study was to compare coronary 64-slice CT angiography (CTA) protocols, specifically prospective electrocardiograph (ECG)-triggered and retrospective ECG-gated CT acquisition performed using a tube voltage of 140 kV and 120 kV, regarding intracoronary stent imaging. Coronary artery stents (n = 12) with artificial in-stent restenosis (50% luminal reduction, 40 HU) on a cardiac phantom were examined by CT at heart rates of 50-75 beats per minute (bpm). The subjective visibility of in-stent restenosis was evaluated with a three-point scale (1 clearly visible, 2 visible, and 3 not visible), and artificial lumen narrowing [(inner stent diameter - measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation - coronary lumen attenuation)/coronary lumen attenuation], and signal-to-noise ratio of in-stent lumen were determined. The effective dose was estimated. The artificial lumen narrowing (mean 43%), the increase of lumen attenuation (mean 46%), and signal-to-noise ratio (mean 7.8) were not different between CT acquisitions (p = 0.12-0.91). However, the visibility scores of in-stent restenosis were different (p < 0.05) between ECG-gated CTA techniques: (a) 140-kV prospective (effective dose 4.6 mSv), 1.6; (b) 120-kV prospective (3.3 mSv), 1.8; (c) 140-kV retrospective (16.4-18.8 mSv), 1.9; and (d) 120-kV retrospective (11.0-13.4 mSv), 1.9. Thus, 140-kV prospective ECG-triggered CTA improves coronary in-stent restenosis visibility at a lower radiation dose compared with retrospective ECG-gated CTA.

Radiation Dose, Image Quality, Stenosis Measurement, and CT Densitometry Using ECG-Triggered Coronary 64-MDCT Angiography: A Phantom Study

The purpose of this study was to compare prospective ECG-triggered and retrospective ECG-gated coronary 64-MDCT angiography as to radiation dose, image quality, accuracy of stenosis measurement, and CT densitometry. Coronary artery models (n = 3) with different plaque densities (approximately 50, approximately 110, and approximately 1,000 H) on a cardiac phantom were scanned in variable heart rate sequences (n = 14) with both prospective ECG-triggered and retrospective ECG-gated scanning. Radiation dose, image quality graded by motion and stairstep artifacts (grade 1, excellent, to grade 4, poor, with grades 1 and 2 defined as satisfactory), accuracy of stenosis measurement (area; 18%, 50%, and 82%), and CT densitometry of plaques (soft, approximately 50; and intermediate, approximately 110 H) were compared between the two protocols using the Mann-Whitney U test and repeated measures. The radiation dose of prospective ECG-triggered CT angiography (CTA) (3.0 mSv) was lower than that of retrospective ECG-gated CTA (11.7-13.0 mSv) when the same tube current (mA) and voltage (kVp) were used in both methods. Prospective ECG-triggered CTA images were assigned a satisfactory quality rating in stable heart rate up to 75 beats per minute (bpm) when using the minimal X-ray exposure time. In this range, there were no significant differences in stenosis measurement (p = 0.17) and CT densitometry (p = 0.93) between the two protocols. Prospective ECG-triggered coronary 64-MDCT has the potential to reduce radiation exposure while maintaining the diagnostic performance of retrospective ECG-gated coronary 64-MDCT.

Noninvasive assessment of coronary stents in patients by 16-slice computed tomography

Background The usefulness of thin-slice multi-detector computed tomography (MDCT) has been highly expected to assess the lumens of coronary artery stents. We evaluated the usefulness of 16-slice MDCT to assess the in-stent lumen after coronary artery stenting. Methods In 42 consecutive patients after coronary artery stenting, retrospective ECG-gated CT-angiography using 16-slice MDCT (0.5-s rotation time, 16 × 0.625-mm detector collimation) was performed. The qualitative assessability of the lumens of 61 coronary stents (14 different types) by MDCT and the reasons for non-assessability were investigated. Furthermore, the evaluation of in-stent restenosis in 21 assessable stents of 16 patients, inluding quantitative density analysis by MDCT, was performed and the results were compared with those of conventional coronary angiography (CAG). Results Of 61 stents, 42 (68.9%) were assessable. The assessability of diameter ≥ 3.5-mm stents made of stainless steel or cobalt was high (88.6%, 31/35), that of 3.0-mm stents was low (57.9%, 11/19) and all 2.5-mm stents were non-assessable due to partial volume effects and metal artifacts of stents. The lumens of stents made of tantalum were totally obscured and the metal artifacts of Bestent2 (gold markers) and S670 were severer than others. All non-assessable stents due to banding artifact and calcification were implanted in segment #1–3 and #6, respectively. In comparison to CAG, MDCT correctly detected the 5 in-stent restenoses and identified absence of restenoses was influenced strongly by the stent strut. Conclusion Despite some limitations, 16-slice MSCT is sufficiently useful for assessment of various coronary stents in patients and can detect in-stent restenoses of assessable stents with high accuracy in comparison to CAG.