Systolic Reconstructions Research Articles

Relationship between heart rate and optimal reconstruction phase in coronary CT angiography performed on a 256-slice multidetector CT.

This study aimed to evaluate the relationship between heart rate (HR) and optimal reconstruction phase in prospectively electrocardiogram (ECG)-triggered coronary CT angiography (CCTA) performed on a newly introduced 256-slice multidetector CT (MDCT). All the cases were selected retrospectively from the patients scheduled for CCTA in our department between January and April 2017. The scanner selected the optimal exposure phase based on 10 s ECG recordings. To ensure the success of CCTA, the operator also checked patient's age, breathing control, emotional status and past medical history to decide whether the automatically selected scan phase needs manual adjustment or not. Images were reconstructed in 1% steps of the R-R interval to determine the cardiac phase with least coronary motion. If CCTA images showed moderate motion blurring or discontinuity in the course of coronary segments, a cardiac motion correction algorithm was applied to the reconstructed images. Subjective diagnostic image quality was evaluated with 4-point grading scale. A total of 87 consecutive CCTA examinations were investigated in this study. Diastolic reconstruction was applied to all vessel segments in patients with HR <63 bpm, where 36.5 and 77.8% of vessel segments were reconstructed with the use of motion correction in HR ≤57 and 58-62 bpm, respectively. As for patients with HR ≥63 bpm, 89.3 and 71.7% of vessel segments were reconstructed in diastole in HR 63-67 and ≥68 bpm, respectively, while 81 and 100% of vessel segments were reconstructed with the use of motion correction in the same HR groups. Based on our results, a HR less than 67 bpm can be used to identify appropriate patients for diastolic reconstruction. Although the motion correction algorithm is an effective approach to reduce the impact of cardiac motion in CCTA, HR control is still important to optimize the image quality of CCTA. The relationship between HR and optimal reconstruction phase established in this study could be further used to tailor the ECG pulsing window for dose reduction in patients undergoing CCTA performed on the 256-slice MDCT. The HR thresholds to identify patients who are the best suitable candidates for diastolic or systolic reconstruction are scanner specific. This study investigated the relationship between HR and optimal reconstruction phase in prospectively ECG-triggered CCTA for a newly introduced 256-slice MDCT. Once the relationship is established, it could be used to tailor the ECG pulsing window for radiation dose reduction.

Maximum Aortic Valve Opening Phase for Annulus Sizing in Pre-TAVR CTA

The optimal phase for the measurement of the aortic annular area for transcatheter aortic valve replacement (TAVR) is not standardized, although most agree that systolic measurements are preferred, when the annulus is larger. We hypothesized that the maximum annular area occurs at the cardiac phase of the maximum aortic valve opening (MAVO) and that this phase can be accurately and reproducibly assessed by visual inspection only. The aortic valve opening area was inspected visually by two readers to determine the MAVO phase. The annular area was measured at the MAVO phase and the typical systolic phase (35% of the R-R interval). Differences in the annular area that would change valve sizing for prostheses were noted. Fifty patients (mean age 81) were studied. Ninety percent had the MAVO at the 15%-25% R-R interval. There was high interobserver correlation (0.89) for determining the MAVO phase by visual inspection. For 49 out of 50 patients, the annular area was maximal at the MAVO phase. The mean difference in the annular area between the MAVO phase and 35% was 22.3 (±4.57) mm2. In 12% of the patients, the difference in the annular area changed the recommended size of a self-expanding prosthesis and would have altered the procedure in 32% for balloon-expandable prostheses. Visually assessed MAVO occurs in early systole for most patients and is almost always the cardiac phase of the maximal aortic annular area. This method allows rapid and reproducible determination of the appropriate phase for TAVR planning measurements. Consideration should be given to optimizing pre-TAVR computed tomography acquisitions for early systolic reconstruction and visual determination of the MAVO.

Assessment of a transcatheter heart valve prosthesis with multidetector computed tomography: in vitro and in vivo imaging characteristics

Multidetector-row computed tomography (MDCT) image quality (IQ) of the commonly implanted Sapien prosthesis was assessed both in vitro and in vivo. The prosthesis was imaged in an in vitro model with a 256-slice CT system under pulsatile conditions using three protocols (1) retrospectively ECG-gating at 120 kV/600 mAs and (2) 140 kV/406 mAs, and (3) prospective triggering at 120 kV/210 mAs (10 acquisitions per protocol). After reconstruction in three perpendicular planes, IQ of the supra-,peri-,sub-,and intraprosthetic as well as leaflet regions was scored on a four-point scale (1 = non-diagnostic, 2 = moderate, 3 = good and 4 = excellent) by two observers. IQ was also assessed for twenty-one post-operative scans. The in vitro scans of the two retrospective protocols and twenty-one in vivo scans were analyzed during systole and diastole. The prospectively triggered scans were analyzed during diastole. Except for the valve leaflets in 5 systolic reconstructions, the in vitro scores were moderate to excellent. In vivo, 7 systolic and 3 diastolic reconstructions of the valve leaflets were non-diagnostic as well as 3 peri-prosthetic regions in diastole. All other scores were moderate to excellent. The Sapien prosthesis surrounded by a radiopaque stainless steel stent can be visualized with MDCT with moderate to good IQ, except for the valve leaflet region that has generally non-diagnostic or moderate IQ.

A comparison of reconstruction and viewing parameters on image quality and accuracy of stress myocardial CT perfusion

Myocardial stress computed tomography perfusion (CTP) has similar diagnostic accuracy for detecting perfusion defects (PDs) versus single-photon emission computed tomography (SPECT). However, the optimal diagnostic viewing and image processing parameters for CTP are unknown. We sought to compare the diagnostic accuracy of different image processing techniques, cardiac phases, slice thicknesses, and viewing parameters for detection of PDs. A stress and rest dual-source CTP protocol was performed with adenosine. Twelve subjects with severe stenosis proven by quantitative coronary angiography (QCA), with corresponding territorial defects at SPECT, were selected as well as 7 controls (subjects with similar clinical suspicion but negative QCA and SPECT). Short-axis stress images were processed with 3 techniques: minimum intensity projection (MinIP), maximum intensity projection, and average intensity multiplanar reconstruction (MPR), 3 thicknesses (1, 3, 8 mm), and 2 phases (systolic, mid-diastolic). The resulting images (n = 1026) were randomized and interpreted by independent readers. Diastolic reconstructions (8-mm MPR) showed the highest sensitivity (81%) to detect true PDs. The highest accuracy was achieved with the 8-mm (61%) and 1-mm (61%) MPR diastolic images. The most sensitive and accurate systolic reconstructions were 3-mm MinIP images. These findings related to viewing in relatively narrow window width and window level settings. Viewing parameters for optimal accuracy in detection of perfusion defects on CTP differ for systolic and diastolic images.

Optimal systolic and diastolic reconstruction windows for coronary CT angiography using 320-detector rows dynamic volume CT

To investigate the optimal pattern of systolic and diastolic reconstruction windows for coronary computed tomography (CT) angiography using 320-detector rows dynamic volume CT (DVCT). A prospective analysis was performed on the data from 77patients who were admitted between December 2008 and July 2009 for DVCT. The images were reconstructed in 10% steps throughout the 10-100% of R-R interval. Data sets for the three major coronary arteries [right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX)] were evaluated by two independent readers. The quality of the images from each examined artery was graded from 1 (no motion artefacts) to 4(severe motion artefacts over the entire vessel). The optimal systolic and diastolic reconstruction windows and the relationship between image quality and heart rate (HR) were analysed. The HR at which the optimal reconstruction window shifted from diastole to systole was predicted. The average HR during imaging was 69.5±12.8 beats/min (range 46-102beats/min). HR was positively correlated with the proportion of systole (r=0.78, p<0.001). As HR increased, the optimal reconstruction windows shifted to later phases in both systole and diastole. Image quality for optimal systolic and diastolic reconstructions both deteriorated significantly with higher HRs (r=0.38, p<0.001; r=0.82, p<0.001). However, image quality in systolic reconstructions did not deteriorate as much as in diastolic reconstructions. The cut-off HRs at which optimal reconstruction intervals turned from diastole to systole was 90.8beats/min. In patients with a low HR, the optimal coronary reconstruction window is in mid-late diastole. As the HR increases, systolic reconstruction often yields superior image quality compared with diastolic reconstruction.

Systolic reconstruction in patients with low heart rate using coronary dual-source CT angiography

The purpose of our study was to determine the relationship between the predictive factors and systolic reconstruction (SR) as an optimal reconstruction window in patients with low heart rate (LHR; less than 65 bpm). 391 patients (262 male and 129 female, mean age; 67.1±10.1 years of age) underwent coronary CTA without the additional administration of a beta-blocker. Affecting factors for SR were analyzed in age, gender, body weight (BW), diabetes mellitus (DM), coronary arterial disease (CAD), ejection fraction (EF), systolic and diastolic body pressure (BP) and heart rate variability (HRV) during coronary CTA. In 29 (7.4%) of the 391 patients, SR was needed, but there was no apparent characteristic difference between the systolic and diastolic reconstruction groups in terms of gender, age, BW, DM, CAD and EF. In a multivariate analysis, the co-existence of DM [P<0.05; OR, 0.27; 95% CI, 0.092-0.80], diastolic BP [P<0.01; OR, 0.95; 95% CI, 0.92-0.98] and HRV [P<0.01; OR, 0.98; 95% CI, 0.96-0.99] were found to be the factors for SR. In gender-related analysis, HRV was an important factor regardless of sex, but co-existence of DM affected especially for female and BP for male. Especially in the patients with LHR who had a medication of DM, high HRV or high BP, SR, in addition to DR, was needed to obtain high-quality coronary CTA images.

Robustness of end-systolic reconstructions in coronary dual-source CT angiography for high heart rate patients

Reconstruction of cardiac computed tomography (CT) images is challenging when the heart rate is higher than 65 beats per minute (bpm). The optimal reconstruction time is often found to be at the end-systolic phase, but image quality remains uncertain. Using dual-source (DS) CT and 83-ms temporal resolution, we evaluated the robustness of the temporal window with low motion during the end systole. We studied 41 DSCT in consecutive patients with a heart rate >65 bpm. Eleven systolic reconstructions were performed every 20 ms between 200 ms and 400 ms of the R-R interval. The end-systolic temporal window (ESTW) was defined as the interval between the first and last selected phases judged adequate for diagnosis. Heart rates varied from 67 to 150 bpm. ESTW was always to be found greater than 100 ms. The mean ESTW was 178 ms (SD: 57 ms), and varied independently of heart rate. All data sets achieved diagnostic quality during the end-systolic phase at a time point between 35 and 50% of the R-R interval. Our data suggest that CT with a temporal window below 100 ms may provide acceptable systolic reconstructions at any heart rate, in a large proportion of patients.

Untersuchung der regionalen und globalen linksventrikulären Funktion mit der Dual-Source-Computertomografie im Vergleich zur Magnetresonanztomografie

To determine regional and global left ventricular (LV) functional parameters and to perform segmental wall thickness (SWT) and motion (WM) analysis of dual-source CT (DSCT) with optimized temporal resolution versus MRI. 30 patients with known or suspected CAD, non-obstructive HCM, DCM, ARVCM, Fallot Tetralogy, cardiac sarcoidosis and cardiac metastasis underwent DSCT and MRI. The DSCT and MR images were evaluated: end-systolic (ESV), end-diastolic LV (EDV) volumes, stroke volume (SV), ejection fraction (EF), and myocardial mass (MM) as well as LV wall thickening and segmental WM applying the AHA model were obtained and statistically analyzed. The mean LV-EDV (r = 0.96) and ESV (r = 0.98) as well as LV-EF (r = 0.97), SV (r = 0.83), and MM (r = 0.95) correlated well. Bland Altman analysis revealed little systematic underestimation of LV-EF (-1.1 +/- 7.8 %), EDV (-0.3 +/- 18.2 ml), SV (-1.3 +/- 16.7 ml) and little overestimation of ESV (1.1 +/- 7.8 ml) and MM (12.8 +/- 14.4 g) determined by DSCT. Systolic reconstruction time points correlated well (DSCT 32.2 +/- 6.7 vs. MRI 35.6 +/- 4.4 % RR-interval). The LV wall thickness obtained by DSCT and MRI showed close correlation in all segments (Ø diff 0.42 +/- 1 mm). In 413 segments (89 %) WM abnormalities were equally rated, whereas DSCT tended to underestimate the degree of wall motion impairment. DSCT with optimized temporal resolution enables regional and global LV function analysis as well as segmental WM analysis in good correlation with MRI. However, the degree of WM impairment is slightly underestimated by DSCT.

Coronary CT angiography: automatic cardiac-phase selection for image reconstruction

We evaluated an algorithm for automatic selection of the cardiac phase with the least motion for image reconstruction at coronary computed tomography (CT) angiography (CCTA). We analyzed data of 100 patients (49 female, mean age 59 years) who had undergone retrospectively ECG-gated CCTA. Two experienced observers visually identified the most suitable end-systolic and end-diastolic phases using a series of image reconstructions in 5% increments across the RR cycle. The same data were then reconstructed using an automatic phase finding algorithm based on a 4D weighting function of cardiac motion. On average, the algorithm determined the most suitable systolic reconstruction phase at 40.11 +/- 6.29% RR compared with 40.07 +/- 5.58% RR by the human observers (p = NS). The most suitable diastolic phase was found at 72.71 +/- 7.37% RR by the automatic algorithm, compared with 76.43 +/- 6.35% RR by the observers (p < 0.05). No statistically significant difference was found between automatically and visually determined reconstruction phases regarding motion and stair-step artifacts in either systole or diastole (p > 0.05). Thus, there appears to be no relevant difference between an automatic phase finding algorithm and visual selection by experienced observers for determining the phase with the least cardiac motion for CCTA image reconstruction. The use of automatic phase finding may therefore facilitate the performance of cardiac CT and reduce human error.

Noninvasive Coronary Angiography Using Dual-Source Computed Tomography in Patients With Atrial Fibrillation

Despite constant improvements in scanner technology, reliable visualization of the coronary arteries with multislice spiral CT angiography (CTA) remains a major challenge in patients with atrial fibrillation (AF). The purpose of this study was to assess the image quality of coronary CT angiograms with coronary angiography, using a dual-source CT scanner (DSCT), comparing systolic and diastolic reconstruction techniques. Additionally, we sought to evaluate the diagnostic accuracy of DSCT with coronary angiography as the standard of reference. Sixty-eight patients with permanent AF were imaged on a DSCT system, with a temporal resolution of 82 milliseconds. The volume and flow rate of the contrast medium were adapted to the patient's body weight. The patients were not receiving any drugs for heart rate regulation. Each dataset was reconstructed at an absolute delay determined from the R wave at 300 milliseconds (ie, systolic reconstruction), as well as at 70% of the RR-cycle (diastolic reconstruction). Twenty-one patients underwent both DSCT and coronary angiography. Two blinded independent readers assessed significant stenoses (> or =50%), and image quality in terms of visibility and artifacts (4-point rating scale: 1 = excellent, 2 = good, 3 = poor, 4 = insufficient) on a per-patient- and a per-segment-based analysis (15-segment AHA model) for both the systolic and diastolic datasets. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. : During 68 DSCT examinations, the mean heart rate ranged between 26 and 181 beats per minute (77 +/- 25). In the patient-based analysis, the image qualities of 64 of 68 CT angiograms (94%) were high enough to permit diagnosis, ie, 4 of 68 (6%) datasets were considered nonevaluable. Segment-based, a total of 898 of 979 coronary artery segments were rated as diagnostically evaluable (92%).In 57 of 68 evaluable patients (84%) the reconstructions in stole had fewer motion artifacts and thus showed superior image quality. The median image quality of all CT datasets was 2. In 21 patients undergoing both coronary angiography and DSCT, the overall sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of significant stenoses were 89% (16 of 18), 98% (260 of 265), 76% (16 of 21), and 99% (260 of 262), respectively, in the per-segment analysis (including 283 vessel segments) and 90% (9 of 10), 82% (9 of 11), 82% (9 of 11), and 90% (9 of 10), respectively, in the patient-based analysis. The image quality of coronary CT angiograms obtained with a DSCT is satisfactory in most patients with AF. In the majority of patients with high and irregular heart rate, the absolute forward approach with end-systolic reconstruction 300 milliseconds after the R-peak yield a higher image quality than diastolic reconstructions. As a result of a significant improvement in temporal resolution, DSCT coronary angiography is feasible in patients with AF and can be used to exclude coronary artery disease in this patient cohort.

Automatic selection of optimal systolic and diastolic reconstruction windows for dual-source CT coronary angiography

The aim of this study was to assess the performance of a motion-map algorithm that automatically determines optimal reconstruction windows for dual-source coronary CT angiography. In datasets from 50 consecutive patients, optimal systolic and diastolic reconstruction windows were determined using the motion-map algorithm. For manual determination of the optimal reconstruction window, datasets were reconstructed in 5% steps throughout the RR interval. Motion artifacts were rated for each major coronary vessel using a five-point scale. Mean motion scores using the motion-map algorithm were 2.4 +/- 0.8 for systolic reconstructions and 1.9 +/- 0.8 for diastolic reconstructions. Using the manual approach, overall motion scores were significantly better (1.9 +/- 0.5 and 1.7 +/- 0.6, p < 0.05), but diagnostic image quality was reached in >90% of cases using either approach. Using the automated approach, there was a negative correlation between heart rate and motion scores for systolic reconstructions (rho = -0.26, p < 0.05) and a positive correlation for diastolic reconstructions (rho = 0.46, p < 0.01). For the manual approach, no significant correlation was found for systolic reconstructions (rho = -0.1, p = 0.52), while there was a positive correlation for diastolic reconstructions (rho = 0.48, p < 0.01). Thus, the motion-map algorithm is a useful tool to save time in finding an appropriate reconstruction window in patients with heart rates <70 bpm (diastolic reconstruction) and >80 bpm (systolic reconstruction).

Detection of myocardial infarction by dual-source coronary computed tomography angiography using quantitated myocardial scintigraphy as the reference standard

Background:Dual-source coronary computed tomography angiography (DS-CTA) has the potential to assess both coronary anatomy and myocardial perfusion. We studied the ability of DS-CTA to detect myocardial infarction (MI) compared to...

Image quality on dual-source computed-tomographic coronary angiography

Multi-detector CT reliably permits visualization of coronary arteries, but due to the occurrence of motion artefacts at heart rates >65 bpm caused by a temporal resolution of 165 ms, its utilisation has so far been limited to patients with a preferably low heart rate. We investigated the assessment of image quality on computed tomography of coronary arteries in a large series of patients without additional heart rate control using dual-source computed tomography (DSCT). DSCT (Siemens Somatom Definition, 83-ms temporal resolution) was performed in 165 consecutive patients (mean age 64 +/- 11.4 years) after injection of 60-80 ml of contrast. Data sets were reconstructed in 5% intervals of the cardiac cycle and evaluated by two readers in consensus concerning evaluability of the coronary arteries and presence of motion and beam-hardening artefacts using the AHA 16-segment coronary model. Mean heart rate during CT was 65 +/- 10.5 bpm; visualisation without artefacts was possible in 98.7% of 2,541 coronary segments. Only two segments were considered unevaluable due to cardiac motion; 30 segments were unassessable due to poor signal-to-noise ratio or coronary calcifications (both n = 15). Data reconstruction at 65-70% of the cardiac cycle provided for the best image quality. For heart rates >85 bpm, a systolic reconstruction at 45% revealed satisfactory results. Compared with earlier CT generations, DSCT provides for non-invasive coronary angiography with diagnostic image quality even at heart rates >65 bpm and thus may broaden the spectrum of patients that can be investigated non-invasively.

Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval

The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1 +/- 10.7 years). Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent observers assessed the image quality of each coronary segments using a five-point scale (from 0 = not evaluative to 4 = excellent quality). A total of 289 coronary segments in 20 heart transplant recipients were evaluated. Mean heart rate during the scan was 89.1 +/- 10.4 bpm. At the best reconstruction interval, diagnostic image quality (score > or = 2) was obtained in 93.4% of the coronary segments (270/289) with a mean image quality score of 3.04 +/- 0.63. Systolic reconstruction intervals provided better image quality scores than diastolic reconstruction intervals (overall mean quality scores obtained with the systolic and diastolic reconstructions 3.03 +/- 1.06 and 2.73 +/- 1.11, respectively; P < 0.001). Different systolic reconstruction intervals (35%, 40%, 45% of RR interval) did not yield to significant differences in image quality scores for the coronary segments (P = 0.74). Reconstructions obtained at the systolic phase of the cardiac cycle allowed excellent diagnostic image quality coronary angiograms in heart transplant recipients undergoing DSCT coronary angiography.

Optimal Systolic and Diastolic Reconstruction Windows for Coronary CT Angiography Using Dual-Source CT

The purpose of this study was to determine the position of the optimal systolic and diastolic reconstruction intervals for coronary CT angiography using dual-source CT. In 90 patients, coronary dual-source CT angiography was performed without beta-blocking agents. Data were reconstructed in 5% steps throughout the R-R interval. Two independent readers selected optimal systolic and diastolic reconstruction windows for each major coronary vessel--the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX)--using a 3D viewer and volume-rendering displays. The motion score for each vessel was graded from 1 (no motion artifacts) to 5 (severe motion artifacts over entire vessel). The average heart rate of all patients was 68.7 beats per minute (bpm) (range, 43-119 bpm). The median optimal systolic reconstruction windows were at 35%, 30%, and 35% for the RCA, LAD, and LCX, respectively. The median optimal diastolic reconstruction window was at 75% for all vessels. The mean motion scores (+/- SD) in the systolic reconstructions were 1.9 +/- 0.8 (RCA), 1.7 +/- 0.5 (LAD), and 2.0 +/- 0.6 (LCX). The mean motion scores for the diastolic reconstructions were 1.7 +/- 0.9, 1.5 +/- 0.6, and 1.6 +/- 0.7, respectively. In patients with a heart rate of < 70 bpm, motion scores were significantly lower in diastole versus systole (1.3 +/- 0.4 and 1.9 +/- 0.5, respectively; p < 0.01). In most patients with a heart rate of > 80 bpm, motion scores were lower in systolic than in diastolic reconstructions (2.1 +/- 0.6 and 2.6 +/- 0.8, respectively; p < 0.05). Using dual-source CT, the overall optimal reconstruction window is at 75% of the R-R interval in patients with low or intermediate heart rates. In patients with heart rates of > 80 bpm, systolic reconstructions often yield superior image quality compared with diastolic reconstructions.