Coronary calcium mass scores measured by identical 64-slice MDCT scanners are comparable: a cardiac phantom study

To assess whether absolute mass scores are comparable or differ between identical 64-slice MDCT scanners of the same manufacturer and to compare absolute mass scores to the physical mass and between scan modes using a calcified phantom. A non-moving anthropomorphic phantom with nine calcifications of three sizes and three densities was scanned 30 times on three 64-slice MDCT scanners of manufacturer A and on three 64-slice MDCT scanners of manufacturer B in both sequential and spiral scan mode. The mean mass scores and mass score variabilities of seven calcifications were determined for all scanners; two non-detectable calcifications were omitted. It was analyzed whether identical scanners yielded similar or significantly different mass scores. Furthermore mass scores were compared to the physical mass and mass scores were compared between scan modes. The mass score calibration factor was determined for all scanners. Mass scores obtained on identical scanners were similar for almost all calcifications. Overall, mass score differences between the scanners were small ranging from 1.5 to 3.4% for the total mass scores, and most differences between scanners were observed for high density calcifications. Mass scores were significantly different from the physical mass for almost all calcifications and all scanners. In sequential mode the total physical mass (167.8 mg) was significantly overestimated (+2.3%) for 4 out of 6 scanners. In spiral mode a significant overestimation (+2.5%) was found for system B and a significant underestimation (−1.8%) for two scanners of system A. Mass scores were dependent on the scan mode, for manufacturer A scores were higher in sequential mode and for manufacturer B in spiral mode. For system A using spiral scan mode no differences were found between identical scanners, whereas a few differences were found using sequential mode. For system B the scan mode did not affect the number of different mass scores between identical scanners. Mass scores obtained in the same scan mode are comparable between identical 64-slice CT scanners and identical 64-slice CT scanners on different sites can be used in follow-up studies. Furthermore, for all systems significant differences were found between mass scores and the physical calcium mass; however, the differences were relatively small and consistent

Stillbirth and neonatal mortality in pregnancies complicated by major congenital anomalies:Findings from a large European cohort

Objective: To provide prognostic information to help parents to reach an informed decision about termination or continuation of the pregnancy and to shape peripartum policy based on a large European cohort. Method: Thirteen registries from the European Surveillance of Congenital Anomalies (EUROCAT) network contributed data from January 1, 1998, to December 31, 2011. Terminations for fetal anomalies were excluded. Chromosomal anomalies, syndromes and isolated anomaly groups were distinguished according to EUROCAT guidelines. Perinatal mortality, stillbirths, and early and late neonatal mortality rates (NMRs) were analyzed by anomaly group and gestational age. Results: Among 73337 cases, perinatal mortality associated with congenital anomaly was 1.27 per 1000 births (95% confidence interval, 1.23-1.31). Average stillbirth rate was 2.68% (range 0%-51.2%). Early and late NMR were 2.75% (range 0%-46.7%) and 0.97% (range 0%-17.9%), respectively. Chromosomal anomalies and syndromes, and most isolated anomalies, had significant differences regarding timing of fetal demise compared to the general population. Chromosomal and central nervous system anomalies had higher term stillbirth rates. Conclusions: We found relevant differences between anomalies regarding rates of stillbirth, NMR, and timing by gestational age. Our data can help parents to decide about their unborn child with a congenital anomaly and help inform maternal-fetal medicine specialists regarding peripartum management

Calcium scoring using 64-slice MDCT, dual source CT and EBT: a comparative phantom study

Purpose Assessment of calcium scoring (Ca-scoring) on a 64-slice multi-detector computed tomography (MDCT) scanner, a dual-source computed tomography (DSCT) scanner and an electron beam tomography (EBT) scanner with a moving cardiac phantom as a function of heart rate, slice thickness and calcium density. Methods and materials Three artificial arteries with inserted calcifications of different sizes and densities were scanned at rest (0 beats per minute) and at 50–110 beats per minute (bpm) with an interval of 10 bpm using 64-slice MDCT, DSCT and EBT. Images were reconstructed with a slice thickness of 0.6 and 3.0 mm. Agatston score, volume score and equivalent mass score were determined for each artery. A cardiac motion susceptibility (CMS) index was introduced to assess the susceptibility of Ca-scoring to heart rate. In addition, a difference (Δ) index was introduced to assess the difference of absolute Ca-scoring on MDCT and DSCT with EBT. Results Ca-score is relatively constant up to 60 bpm and starts to decrease or increase above 70 bpm, depending on scoring method, calcification density and slice thickness. EBT showed the least susceptibility to cardiac motion with the smallest average CMS-index (2.5). The average CMS-index of 64-slice MDCT (9.0) is approximately 2.5 times the average CMS-index of DSCT (3.6). The use of a smaller slice thickness decreases the CMS-index for both CT-modalities. The Δ-index for DSCT at 0.6 mm (53.2) is approximately 30% lower than the Δ-index for 64-slice MDCT at 0.6 mm (72.0). The Δ-indexes at 3.0 mm are approximately equal for both modalities (96.9 and 102.0 for 64-slice MDCT and DSCT respectively). Conclusion Ca-scoring is influenced by heart rate, slice thickness and modality used. Ca-scoring on DSCT is approximately 50% less susceptible to cardiac motion as 64-slice MDCT. DSCT offers a better approximation of absolute calcium score on EBT than 64-slice MDCT when using a smaller slice thickness. A smaller slice thickness reduces the susceptibility to cardiac motion and reduces the difference between CT-data and EBT-data. The best approximation of EBT on CT is found for DSCT with a slice thickness of 0.6 mm

The influence of heart rate, slice thickness, and calcification density on calcium scores using 64-slice multidetector computed tomography - A systematic phantom study

Objective: The purpose of this study was to investigate the influence of heart rate, slice thickness, and calcification density on absolute value and variability of calcium score using 64-slice multidetector computed tomography (MDCT). Methods and Materials: Three artificial arteries containing each 3 lesions with varying density were scanned using a moving cardiac phantom at rest and at 50 to 110 beats per minute (bpm) at 10-bpm intervals on a 64-slice MDCT. Images were reconstructed at slice thicknesses (increment) of 0.6 (0.4), 0.75 (0.5), 1.5 (1.5), and 3.0 (3.0) mm. The amount of calcium was expressed as an Agatston score, volume score, and equivalent mass. Results: Absolute coronary artery calcium (CAC) scores decreased [average -37% for low density calcification (LDC)] or increased [average +32% for high density calcification (HDC)] at heart rates over 60 bpm depending on slice thickness and scoring method. Thinner slice thicknesses yielded higher CAC scores. Variability of the CAC scores increased with increasing heart rates especially for low density calcifications (8% at rest vs. 50% at 110 bpm). Variability also increased for thicker slices (average 6% for 0.6 mm vs. 18% for 3.0 mm). Variability was lower for HDC compared with LDC (similar to 5% for HDC vs. 27% for LDC at 70 bpm, averaged over all methods and slice thicknesses). Conclusion: CAC-scoring is strongly influenced by cardiac motion, calcification density, and slice thickness. CAC scores increase for high density calcifications and decrease for low density calcifications at increasing heart rates. Heart rate should be reduced on 64-slice MDCT to obtain a lower degree of variability of CAC-scoring, preferably below 70 bpm. A thinner slice thickness further enhances the reproducibility

Initial results on visualization of coronary artery stents at multiple heart rates on a moving heart phantom using 64-MDCT

Objective: Evaluation of the image quality of coronary artery stents at various heart rates using Multi Detector Computed Tomography (MDCT).Methods: Nine different coronary stents were attached to a moving heart phantom and scanned using a 64-MDCT with a rotation time of 330 milliseconds (ms). The heart rate of the phantom was varied between 0 and 115 beats per minute (bpm). Two independent methods were used to investigate image quality. After reconstruction the average Houndsfield Unit (HU) value in the stent lumen was measured in the longitudinal and the cross-sectional plane. The stent images were then presented to two radiologists. The radiologists were asked to rank the images from good to bad based on lumen visibility and overall image quality. A second ranking was obtained using the CT density values. Finally two rankings were comparedResults: Compared to the value for air, the HU-values measured in the lumen increased by 50 to 700 HU. Average slope value in the longitudinal plane was 1.7 +/- 0.6 HU/bpm, and the average slope value in the cross-sectional plane was 1.7 +/- 0.8 HU/bpm. This shows increased attenuation with increasing heart rate and thus a negative correlation between image quality and heart rate in both planes for all stents. The ranking acquired from the radiologists resembled the measured results as they also showed a negative correlation between the two variables. Using the results of the CT density measurements an analysis was done on multi-segment reconstruction (MSR).Conclusion: A negative correlation between the heart rate and image quality of coronary stents was found by two independent methods. MSR showed no benefit for image quality in this study.</p

Initial results on visualization of coronary artery stents at multiple heart rates on a moving heart phantom using 64-MDCT

Objective: Evaluation of the image quality of coronary artery stents at various heart rates using Multi Detector Computed Tomography (MDCT). Methods: Nine different coronary stents were attached to a moving heart phantom and scanned using a 64-MDCT with a rotation time of 330 milliseconds (ms). The heart rate of the phantom was varied between 0 and 115 beats per minute (bpm). Two independent methods were used to investigate image quality. After reconstruction the average Houndsfield Unit (HU) value in the stent lumen was measured in the longitudinal and the cross-sectional plane. The stent images were then presented to two radiologists. The radiologists were asked to rank the images from good to bad based on lumen visibility and overall image quality. A second ranking was obtained using the CT density values. Finally two rankings were compared Results: Compared to the value for air, the HU-values measured in the lumen increased by 50 to 700 HU. Average slope value in the longitudinal plane was 1.7 +/- 0.6 HU/bpm, and the average slope value in the cross-sectional plane was 1.7 +/- 0.8 HU/bpm. This shows increased attenuation with increasing heart rate and thus a negative correlation between image quality and heart rate in both planes for all stents. The ranking acquired from the radiologists resembled the measured results as they also showed a negative correlation between the two variables. Using the results of the CT density measurements an analysis was done on multi-segment reconstruction (MSR). Conclusion: A negative correlation between the heart rate and image quality of coronary stents was found by two independent methods. MSR showed no benefit for image quality in this study