ECG-gated Scan Research Articles

Comparison of prospective electrocardiography-gating high-pitch mode and without electrocardiography-synchronization high-pitch mode acquisition for the image quality and radiation doses of the aortic using dual-source CT

Objective To evaluate the application of prospective ECG-gating Flash spiral scan mode dual-source CT in aortography,and compare it's image quality and radiation dose with without ECG-synchronization high-pitch spiral scanning mode. Methods Fifty consecutive patients (Group A) with suspected aortic dissection or after operations for the aortic dissection were scanned with prospective ECG-gated high-pitch scan and another 50 consecutive patients (Group B) were analyzed by non-ECG-gated high-pitch scan.Image quality of the aortic was assessed by two independent readers.Image noise was measured,radiation dose estimates were calculated.The imaging quality of the aortic and the radiation dose were compared with Mann-whitney U and t test. Results The average image quality score[ (1.18±0.40) in group A and (1.23±0.31) in group B] showed no significant difference between group A and group B (U=1.20,P=0.23).The mean radiation dose of group A was lower than that of group B[ (1.49±0.38) mSv in group A,(2.79±0.54) mSv in group B,t=13.677,P<0.05]. Conclusion Prospective ECG-gated dual-source CT Flash spiral scanning with low radiation dose and good image quality in the aortic dissection with high value of clinical application. Key words: Aortography; Radiation dose; Tomography,X-ray computed; Quality control

Role of 320-Slice CT Imaging in the Diagnostic Workup of Patients With Chronic Thromboembolic Pulmonary Hypertension

Right-sided heart catheterization (RHC) and pulmonary digital subtraction angiography (PDSA) are the standard methods used in diagnosing suspected or defi nite chronic thromboembolic pulmonary hypertension (CTEPH). We studied the ability of 320-slice CT imaging to detect simultaneously chronic thromboembolic fi ndings in the pulmonary arteries and pulmonary hemodynamics based on the curvature of the interventricular septum (IVS) in CTEPH . Forty-four patients with high clinical suspicion of CTEPH underwent RHC, PDSA, and enhanced double-volume retrospective ECG-gated 320-slice CT scan. We measured the sensitivity and specificity of CT imaging to detect thrombi in the pulmonary arteries compared with PDSA. We also compared IVS bowing (expressed as curvature) measured on the short-axis cine heart image with pulmonary arterial pressure (PAP) obtained by RHC. Compared with PDSA, the sensitivity and specificity of CT imaging to detect chronic thromboembolic findings were 97.0% and 97.1% at the main/lobar level and 85.8% and 94.6% at the segmental level, respectively. The correlation coefficients of IVS curvature with systolic PAP and mean PAP were 2 0.79 ( P , .001) and 2 0.86 ( P , .001), respectively. The use of 320-slice CT imaging allows for less invasive and simultaneous detection of thrombi and evaluation of pulmonary hemodynamics for the diagnostic work-up of CTEPH.

Left atrial volumetry from routine diagnostic work up prior to pulmonary vein ablation is a good predictor of freedom from atrial fibrillation

This study aimed to identify whether left atrial (LA) volume assessed by multidetector computed tomography (MDCT) is related to the long-term success of pulmonary vein ablation (PVA). MDCT is used to guide PVA for the treatment of atrial fibrillation (AF). MDCT permits accurate sizing of LA dimensions. We analysed data from 368 ablation procedures of 279 consecutive patients referred for PVA due to drug-refractory symptomatic AF (age 62 ± 10; 58% men; 71% paroxysmal AF). Prior to the procedure, all patients underwent ECG-gated 64-MDCT scan for assessment of LA and PV anatomy, LA thrombus evaluation, LA volume estimation, and electroanatomical mapping integration. Within a mean follow-up of 356 ± 128 days, 64% of the patients maintained sinus rhythm after the initial ablation, and 84% when including repeat PVA. LA diameter (P = 0.004), LA volume (P = 0.002), and type of AF (P = 0.001) were independent predictors of AF recurrence in univariate analysis. There was a relatively low correlation between the echocardiographic LA diameter and LA volume from MDCT (P = 0.01, r = 0.5). In multivariate analysis, paroxysmal AF (P < 0.006) and LA volume below the median value of 106 mL (P = 0.042) were significantly associated with the success of PVA, whereas LA diameter was not (P = 0.245). Analysing receiver-operator characteristics, the area under the curve for LA volume was 0.73 (P = 0.001) compared with 0.60 (P = 0.09) for LA diameter from echocardiography. LA volume assessed by MDCT is a better predictor of AF recurrence after PVA than echocardiograpic LA diameter and can be derived from the pre-procedural imaging data set.

Life-threatening haemoptysis due to tracheal varices secondary to pulmonary vein obstruction

A 30-year-old man with a 3 day history of increasing breathlessness and frank haemoptysis was suspected of having pulmonary embolism and anticoagulated with heparin. Haemoptysis worsened so anticoagulation was reversed...

128-slice Dual-source Computed Tomography Coronary Angiography in Patients with Atrial Fibrillation: Image Quality and Radiation Dose of Prospectively Electrocardiogram-triggered Sequential Scan Compared with Retrospectively Electrocardiogram-gated Spiral Scan

Objective To evaluate the image quality (IQ) and radiation dose of 128-slice dual-source computed tomography (DSCT) coronary angiography using prospectively electrocardiogram (ECG)-triggered sequential scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrillation referred for a second-generation 128-slice DSCT coronary angiography were included in the prospective study. Of them, 17 patients (sequential group) were randomly selected to use a prospectively ECG-triggered sequential scan, while the other 15 patients (spiral group) used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel-lent (grade 1) to non-assessable (grade 4), based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each patient were compared between the two groups. Results The mean heart rate (HR) of the sequential group was 96±27 beats per minute (bpm) with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean HR (t=1.91, P=0.243) and HR variation range (t=0.950, P=0.350) had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent (grade 1) in 190/244 (78%) vs. 177/217 (82%) by reader1 and 197/245 (80%) vs. 174/214 (81%) by reader2, as non-assessable (grade 4) in 4/244 (2%) vs. 2/217 (1%) by reader1 and 6/245 (2%) vs. 4/214 (2%) by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good (1.27±0.19 vs. 1.25±0.22, Z=-0.834, P=0.404). The effective radiation dose of the sequential group reduced significantly compared with the spiral group (4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000). Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.

Fully automated right ventricular volumetry from ECG-gated coronary CT angiography data: evaluation of prototype software

Enlargement and dysfunction of the right ventricle (RV) is a sign and outcome predictor of many cardiopulmonary diseases. Due to the complex geometry of the RV exact volumetry is cumbersome and time-consuming. We evaluated the performance of prototype software for fully automated RV segmentation and volumetry from cardiac CT data. In 50 retrospectively ECG-gated coronary CT angiography scans the endsystolic (RVVmin) and enddiastolic (RVVmax) volume of the right ventricle was calculated fully automatically by prototype software. Manual slice segmentation by two independent radiologists served as the reference standard. Measurement periods were compared for both methods. RV volumes calculated with the software were in strong agreement with the results from manual slice segmentation (Bland-Altman r = 0.95-0.98; p < 0.001; Lin's correlation Rho = 0.87-0.96, p < 0.001) for RVVmax and RVVmin with excellent interobserver agreement between both radiologists (r = 0.97; p < 0.001). The measurement period was significantly shorter with the software (153 ± 9 s) than with manual slice segmentation (658 ± 211 s). The prototype software demonstrated very good performance in comparison to the reference standard. It promises robust RV volume results and minimizes postprocessing time.

Möglichkeiten der Dosisreduktion bei CT-Untersuchungen des akuten Thoraxschmerzes

Electrocardiogram-gated (ECG) computed tomography (CT) investigations can be accompanied by high amounts of radiation exposure. This is particularly true for the investigation of patients with unclear and acute chest pain. The common approach in patients with acute chest pain is standard spiral CT of the chest. The chest pain or triple-rule-out CT protocol is a relatively new ECG-gated protocol of the entire chest. This article reviews and discusses different techniques for the CT investigation of patients with acute chest pain. By applying the appropriate scan technique, the radiation exposure for an ECG-gated protocol must not necessarily be higher than a standard chest CT scan Aortic pathologies are far better depicted by ECG-gated scan protocols and depending on the heart rate coronary artery disease can also be detected at the same time. The use of ECG-triggered scans will not support the diagnostics of the pulmonary arteries. However, in unspecific chest pain an ECG-triggered scan protocol can provide information on the differential diagnosis.

Preliminary Study of Prospective ECG-Gated 320-Detector CT Coronary Angiography in Patients with Ventricular Premature Beats

BackgroundTo study the applicability of prospective ECG-gated 320-detector CT coronary angiography (CTCA) in patients with ventricular premature beats(VPB), and determine the scanning mode that best maximizes image quality and reduces radiation dose. Methods: 110 patients were divided into a VPB group (60 cases) and a control group (50 cases) using CTCA.All the patients then underwent coronary angiography (CAG) within one month. CAG served as a reference standard through which the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTCA in diagnosing significant coronary artery stenosis (luminal stenosis ≥50%) could be analyzed. The two radiologists with more than 3 years’ experience in cardiac CT each finished the image analysis after consultation. A personalized scanning mode was adopted to compare image quality and radiation dose between the two groups.Methodology/Principal FindingsAt the coronary artery segment level, sensitivity, specificity, PPV, and NPV in the premature beat group were 92.55%, 98.21%, 88.51%, and 98.72% respectively. In the control group these values were found to be 95.79%, 98.42%, 90.11%, and 99.28% respectively. Between the two groups, specificity, sensitivity PPV, NPV was no significant difference. The two groups had no significant difference in image quality score (P>0.05). Heart rate (77.20±12.07 bpm) and radiation dose (14.62±1.37 mSv) in the premature beat group were higher than heart rate (58.72±4.73 bpm) and radiation dose (3.08±2.35 mSv) in the control group. In theVPB group, the radiation dose (34.55±7.12 mSv) for S-field scanning was significantly higher than the radiation dose (15.10±1.12 mSv) for M-field scanning.Conclusions/SignificanceWith prospective ECG-gated scanning for VPB, the diagnostic accuracy of coronary artery stenosis is very high. Scanning field adjustment can reduce radiation dose while maintaining good image quality. For patients with slow heart rates and good rhythm, there was no statistically significant difference in image quality.

Image Quality and Radiation Exposure With Prospectively ECG-Triggered Axial Scanning for Coronary CT Angiography: The Multicenter, Multivendor, Randomized PROTECTION-III Study

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. 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. 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 = nondiagnostic, 4 = excellent image quality). Secondary endpoints included radiation dose and the rate of downstream testing during 30-day follow-up. Image quality in patients scanned with the axial scan protocol (score 3.36 ± 0.59) was not inferior compared with helical scan protocols (3.37 ± 0.59) (p for noninferiority <0.004). Axial scanning was associated with a 69% reduction in radiation exposure (dose-length product [estimated effective dose] 252 ± 147 mGy · cm [3.5 ± 2.1 mSv] vs. 802 ± 419 mGy · cm [11.2 ± 5.9 mSv] for axial vs. helical scan protocols, p < 0.001). The rate of downstream testing did not differ (13.8% vs. 15.9% for axial vs. helical scan protocols, p = 0.555). 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.

Low dose dual-source CT angiography in infants with complex congenital heart disease: A randomized study

To investigate the radiation dose and image quality of prospective ECG-triggering dual-source CT angiography in infants with complex congenital heart disease (CHD) in comparison with retrospective ECG-gated scanning. Ninety-six infants less than 1 year old (60/36 male/female, age: 4.8 ± 2.7 months, weight: 5.8 ± 1.8 kg) with complex CHD were enrolled. Three image acquisition protocols were set: group 1: 80 kV, 100 mA, retrospective ECG-gated protocol; group 2: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 380 ms; group 3: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 200 ms. Patients were selected to any one of the protocols randomly. The signal-to-noise ratios (SNR) were calculated in the ascending aorta and the pulmonary artery trunk. Image quality was assessed by a five-point score. A score of <3 represents non-diagnostic. Effective radiation dose (ED) was calculated. Image quality score of groups 1, 2 and 3 were 4.1 ± 0.4, 4.0 ± 0.6 and 4.2 ± 0.6 (p = 0.224). SNR of ascending aorta and pulmonary artery trunk among them had no statistical difference (all p>0.05). The average ED (median) of groups 1, 2 and 3 were 1.17 ± 0.07 mSv (1.25 mSv), 0.72 ± 0.24 mSv (0.78 mSv) and 0.48 ± 0.41 mSv (0.39 mSv). Any two of the three groups had significant differences (all p<0.001). Prospective ECG-triggering DSCT angiography associated with a significantly lower ED than retrospective protocol, while maintaining image quality for diagnosis. Prospective ECG-triggering DSCT angiography could be used as a very important second-line diagnostic tool in infants with complex CHD.

Coronary computed tomography angiography during arrhythmia: Radiation dose reduction with prospectively ECG-triggered axial and retrospectively ECG-gated helical 128-slice dual-source CT

Arrhythmia during coronary computed tomography angiography (coronary CTA) acquisition increases the risk of nondiagnostic segments and high radiation exposure. An advanced arrhythmia rejection algorithm for prospectively electrocardiogram (ECG)-triggered axial scans using dual-source CT (DSCT) examinations has recently been reported. We compared image quality and effective dose at DSCT examinations using prospectively ECG-triggered axial scanning with advanced arrhythmia rejection software (PT-AAR) versus retrospectively ECG-gated helical scanning with tube-current modulation (RG-TCM) during arrhythmia. This was a retrospective case-control study of 90 patients (43 PT-AAR, 47 RG-TCM) with arrhythmia (defined as heart rate variability [HRV] > 10 beats/min during data acquisition) referred for physician-supervised coronary CTA between April 2010 and September 2011. A subset of 22 cases matched for body mass index, HR, HRV, and other scan parameters was identified. Subjective image quality (4-point scale) and effective dose (dose length product method) were compared. PT-AAR was associated with lower effective dose than RG-TCM (4.1 vs 12.6 mSv entire cohort and 4.3 vs 9.1 mSv matched controls; both P < 0.01). Image quality scores were excellent in both groups (3.9 PT-AAR vs 3.6 RG-TCM) and nondiagnostic segment rates were low (0.1% vs 0.6%). Significantly higher image quality scores were found with PT-AAR in the entire cohort (P < 0.05), and in matched controls with high HRV > 28 beats/min (P < 0.05). In patients with variable heart rates, prospectively ECG-triggered axial DSCT with arrhythmia rejection algorithm is feasible and can decrease radiation exposure by ∼50% versus retrospectively ECG-gated helical DSCT, with preserved image quality.

Association of Mild to Moderate Kidney Dysfunction with Coronary Artery Calcification in Patients with Suspected Coronary Artery Disease

Objectives: To report the association between kidney dysfunction and coronary artery calcification (CAC) score (CACS) among patients with clinically suspected coronary artery disease (CAD). Methods: We prospectively included 1,572 consecutive patients with clinically suspected CAD who underwent ECG-gated cardiac CT scans using 64-multidetector row computed tomography. CACS was quantified using a previously described method. Renal function was assessed by the estimated glomerular filtration rate (eGFR). Ordinal logistic regression and Pearson correlation were used to analyze the association between eGFR and CACS. Results: Patients with higher CACS were older, more had a history of hypertension, diabetes and tobacco use, and they were more likely to have an atherogenic lipid profile, higher systolic blood pressure, diastolic blood pressure, hemoglobin A1c, body mass index and C-reactive protein (CRP) and lower eGFR when compared with those patients without CAC or with lower CACS. The unadjusted correlation coefficient of eGFR and CACS was –0.259 (p < 0.001). This remained significant after adjustment for age, gender, hypertension, diabetes, hyperlipidemia, tobacco use and CRP (R = –0.156, p < 0.001). Ordinal logistic regression analysis showed that age, hypertension, diabetes, CRP and eGFR exerted independent influences on CACS. Conclusions: Kidney dysfunction was an independent predictor of CACS in patients with clinically suspected CAD. Further prospective multicenter studies are needed to confirm this finding.

Lung Image Quality with 320-row Wide-volume CT Scans: The Effect of Prospective ECG-gating and Comparisons with 64-row Helical CT Scans

To evaluate the image quality of 320-row wide-volume (WV) computed tomography (CT) scans in comparison with 64-row helical scans for the lung. The Institutional Review Board of each institution approved this prospective, multicenter study and informed consent was obtained. A total of 73 subjects underwent two types of chest CT, including 320-row WV scans and 64-row helical scans. Both scans used the same tube voltage, tube current, exposure time setting, and slice thickness. The helical scans were not electrocardiogram (ECG)-gated. For the WV scans, prospective ECG-gating was used for 38 subjects, whereas the other 35 subjects did not have ECG-gating. Using a 5-point scale from 1 (nondiagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for five lobes and the lingula. The differences in the scores between WV scans and helical scans were compared using Wilcoxon's signed-rank test. The WV scans with ECG-gating had significantly higher scores than 64-row helical scans for all lobes and lingula (right lower lobe, P < .01; other lobes and lingula, P < .0001, respectively). The 320-row WV scans without ECG-gating also had significantly higher scores than 64-row helical scans (P < .05), except for nonsignificant differences for the left upper lobe. Lung image quality of ECG-gated WV scans, which do not require any additional radiation exposure, is better than that of non-ECG-gated 64-row helical scans. Non-ECG-gated 320-row WV scans are comparable or slightly superior to non-ECG-gated 64-row helical scans.

Evaluation of an Exposed-radiation Dose on a Dual-source Cardiac Computed Tomography Examination with a Prospective Electrocardiogram-gated Fast Dual Spiral Scan

We evaluated exposed-radiation doses on dual-source cardiac computed tomography (CT) examinations with prospective electrocardiogram (ECG)-gated fast dual spiral scans. After placing dosimeters at locations corresponding to each of the thoracic organs, prospective ECG-gated fast dual spirals and retrospective ECG-gated dual spiral scans were performed to measure the absorbed dose of each organ. In the prospective ECG-gated fast dual spiral scans, the average absorbed doses were 5.03 mGy for the breast, 9.96 mGy for the heart, 6.60 mGy for the lung, 6.48 mGy for the bone marrow, 9.73 mGy for the thymus, and 4.58 mGy for the skin. These values were about 5% of the absorbed doses for the retrospective ECG-gated dual spiral scan. However, the absorbed dose differed greatly at each scan, especially in the external organs such as the breast. For effective and safe use of the prospective ECG-gated fast dual spiral scan, it is necessary to understand these characteristics sufficiently.

Inhibition of the Oversensing of Cardiac Pacemakers in Chest CT

Objectives: The purpose of this study is to identify how to manage oversensing of pacemakers in chest CT. Methods: Four different models of pacemakers were examined to select the pacemaker generating oversensing. To the pacemaker with oversensing, intermittent switching X-ray was exposed using ECG-gated CT helical scan system at prospective CTA mode. IVY Model was used to synchronize the ECG. Only during in the alert period that is non-refractory and sensing is available, intermittent switching X-ray (300 msec/sec) was exposed in chest CT. For comparison, the same intermittent switching X-ray (300 msec/sec) was exposed in the refractory period when sensing was not available. Results: Oversensing was detected only in one of the four pacemakers tested. In this pacemaker, oversensing was generated by exposure of the intermittent switching X-ray in the alert (non-refractory) period, but oversensing was not observed in the refractory period. Conclusion: A pacemaker has alert and refractory periods. Oversensing of a pacemaker was found to be inhibited by selective ECG-synchronized exposure in the refractory period. Since all pacemakers have the refractory period, the results of this study can be widely applied to the patients with pacemakers in chest CT, and their chest CT can be operated safely.

A novel iterative reconstruction algorithm allows reduced dose multidetector-row CT imaging of mechanical prosthetic heart valves

Multidetector-row CT is promising for prosthetic heart valve (PHV) assessment but retrospectively ECG-gated scanning has a considerable radiation dose. Recently introduced iterative reconstruction (IR) algorithms may enable radiation dose reduction with retained image quality. Furthermore, PHV image quality on the CT scan mainly depends on extent of PHV artifacts. IR may decrease streak artifacts. We compared image noise and artifact volumes in scans of mechanical PHVs reconstructed with conventional filtered back projection (FBP) to lower dose scans reconstructed with IR. Four different PHVs (St. Jude, Carbomedics, ON-X and Medtronic Hall) were scanned in a pulsatile in vitro model. Ten retrospectively ECG-gated CT scans were performed of each PHV at 120 kV, 600 mAs (high-dose CTDIvol 35.3 mGy) and 120 kV, 300 mAs (low-dose CTDIvol 17.7 mGy) on a 64 detector-row scanner. Diastolic and systolic images were reconstructed with FBP (high and low-dose) and the IR algorithm (low-dose only). Hypo- and hyperdense artifact volumes were determined using two threshold filters. Image noise was measured. Mean hypo- and hyperdense artifact volumes (mm3) were 1,235/5,346 (high-dose FBP); 2,405/6,877 (low-dose FBP) and 1,218/5,333 (low-dose IR). Low-dose IR reconstructions had similar image noise compared to high-dose FBP (16.5 ± 1.7 vs. 16.3 ± 1.6, mean ± SD, respectively, P = 1.0). IR allows ECG-gated PHV imaging with similar image noise and PHV artifacts at 50% less dose compared to conventional FBP in an pulsatile in vitro model.

Assessment of Mitral Valve Stenosis by Helical MDCT: Comparison With Transthoracic Doppler Echocardiography and Cardiac Catheterization

We evaluated the precision of helical MDCT for the quantification of mitral valve stenosis (MVS) compared with transthoracic echocardiography (TTE) and cardiac catheterization. A total of 28 patients with MVS of differing severity underwent an ECG-gated contrast-enhanced MDCT scan. The mitral valve area (MVA) was determined planimetrically by MDCT and was compared with Doppler TTE using the pressure half-time method and with cardiac catheterization using the Gorlin formula. Planimetry of the MVA with MDCT was feasible in all cases. The MVA on MDCT (1.88 ± 0.76 cm(2)) was significantly larger than that seen with TTE (1.74 ± 0.75 cm(2); p = 0.039) or cardiac catheterization (1.72 ± 0.67 cm(2); p = 0.037). The correlation between MDCT and TTE (r = 0.90; p < 0.001; limits of agreement, ± 0.65 cm(2)) and that between MDCT and cardiac catheterization (r = 0.86; p < 0.001; limits of agreement, ± 0.76 cm(2)) were good and similar to the correlation between TTE and cardiac catheterization (r = 0.88; p < 0.001; limits of agreement, ± 0.71 cm(2)). The best cutoff level for detecting moderate-to-severe stenosis at MDCT was an MVA of 1.70 cm(2), resulting in a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 73%, 88%, 82%, 80%, and 83%, respectively, with two false-positive and three false-negative results. The MVA planimetrically determined by MDCT is systematically larger than those calculated by Doppler TTE and cardiac catheterization. However, because of a good correlation between methods and adjustment for the systematic bias, MDCT may allow reliable quantification of MVS and effectual discrimination among severity grades, although discrepancies between methods remain in individual cases.

Evaluating radiation dose of 128-slice dual-source computed tomographic coronary angiography with different electrocardiogram pulsing models

To determine the effects of heart rate frequency (HRF) and heart rate variability (HRV) on radiation exposure and image quality in a large cohort of patients undergoing DSCT (dual-source computed tomograph) coronary angiography with three different electrocardiogram (ECG) pulsing models, to prospectively investigate CT image quality parameters by using different protocols and to calculate the radiation dose estimates for noninvasive coronary angiography performed by DSCT. Over a 1-month period, 253 consecutive patients were recruited and categorized into 3 groups: Group A:low HRF (≤ 75 beats/min) with normal-minor heart rate variability (HRV) (mean interbeat difference (IBD), 0 - 3), coronary CT angiography proceeding with prospective ECG-triggered flash spiral scan; Group B: intermediate-high HRF (> 75 beats/min) with normal-minor HRV (IBD, 0 - 4), with prospective ECG-triggered sequence scan; Group C: intermediate-high HRF (> 75 beats/min) with moderate-severe HRV (IBD ≥ 5) with retrospective ECG-gated spiral scan. CT coronary angiography yielded excellent image quality in 87.7% of patients (222/253). No significant differences were found among three groups with different HRF and HRV in image quality and diagnostic performance. Radiation exposure was significantly higher in patients with low versus high HRF and in patients with severe versus normal HRV. Significant difference (P < 0.001) was found among the effective doses of group A (mean ± standard deviation, 0.602 ± 0.363 mSv), group B (1.253 ± 0.804 mSv) and group C (9.039 ± 5.657 mSv). The higher temporal resolution of dual-source spiral CT coronary angiography performed with adaptive ECG pulsing results in preserved diagnostic image quality and performance independent of HRF or HRV at the cost of limited dose reduction in arrhythmic patients.

Ventricular septal aneurysms in adults: findings of cardiac CT images and correlation with clinical features

With the increasing use of multidetector computed tomography (MDCT), the number of incidentally detected ventricular septal aneurysms (VSAs) in adults has increased. However, to date, there are not sufficient well-organized data regarding VSAs in adults on MDCT. To evaluate the CT findings of ventricular septal aneurysms (VSAs) in adults and correlate the findings with clinical features. We performed a retrospective review of the cardiac CT reports in our electronic database of 3402 patients who underwent ECG-gated cardiac CT scans using a 64-slice multidetector CT or dual-source CT from October 2006 to December 2009 at our institute. Among them, eight patients were diagnosed with a VSA. We evaluated the location, size, and morphology of VSAs on cardiac CT angiographies (CCTAs) and correlated the findings with the clinical features of the patients. On CCTAs, all eight patients were found to have VSAs in the membranous portion of the interventricular septum and toward the right ventricle. The VSAs were 10-22 mm at their longest diameter and had wide necks. The VSAs were lobulated along the outer margin and were incidental findings in all patients. Four of the eight patients had a conduction abnormality such as first-degree atrio-ventricular block or incomplete right bundle branch block seen on ECG, whereas the other four patients had normal ECGs. VSA in adults is usually detected incidentally. It is seen in the membranous portion of the interventricular septum with a lobulated shape on CCTA. It is occasionally associated with a conduction anomaly.

Automated coronary artery tree extraction in coronary CT angiography using a multiscale enhancement and dynamic balloon tracking (MSCAR-DBT) method

Rational and objectives To evaluate our prototype method for segmentation and tracking of the coronary arterial tree, which is the foundation for a computer-aided detection (CADe) system to be developed to assist radiologists in detecting non-calcified plaques in coronary CT angiography (cCTA) scans. Materials and methods The heart region was first extracted by a morphological operation and an adaptive thresholding method based on expectation-maximization (EM) estimation. The vascular structures within the heart region were enhanced and segmented using a multiscale coronary response (MSCAR) method that combined 3D multiscale filtering, analysis of the eigenvalues of Hessian matrices and EM estimation segmentation. After the segmentation of vascular structures, the coronary arteries were tracked by a 3D dynamic balloon tracking (DBT) method. The DBT method started at two manually identified seed points located at the origins of the left and right coronary arteries (LCA and RCA) for extraction of the arterial trees. The coronary arterial trees of a data set containing 20 ECG-gated contrast-enhanced cCTA scans were extracted by our MSCAR-DBT method and a clinical GE Advantage workstation. Two experienced thoracic radiologists visually examined the coronary arteries on the original cCTA scans and the rendered volume of segmented vessels to count the untracked false-negative (FN) segments and false positives (FPs) for both methods. Results For the visible coronary arterial segments in the 20 cases, the radiologists identified that 25 segments were missed by our MSCAR-DBT method, ranging from 0 to 5 FN segments in individual cases, and that 55 artery segments were missed by the GE software, ranging from 0 to 7 FN segments in individual cases. 19 and 15 FPs were identified in our and the GE coronary trees, ranging from 0 to 4 FPs for both methods in individual cases, respectively. Conclusion The preliminary study demonstrates the feasibility of our MSCAR-DBT method for segmentation and tracking coronary artery trees. The results indicated that both our method and GE software can extract coronary artery trees reasonably well and the performance of our method is superior to that of GE software in this small data set. Further studies are underway to develop methods for improvement of the segmentation and tracking accuracy.