Diagnostic value of 320-slice coronary CT angiography in coronary artery disease: A systematic review and meta-analysis

The aim of this study is to perform a systematic review and meta-analysis of the diagnostic value of 320-slice coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease when compared to invasive coronary angiography. A search of different databases was conducted to identify studies investigating the diagnostic value of 320-slice coronary CT angiography. Sensitivity, specificity, positive and negative predictive value estimates pooled across studies were tested using a fixed effects model and analysed at patient-, vessel- and segment-based assessment. Twelve studies comprising 1592 patients (median, 63 patients, range, 37-240 patients) with a total of 2974 vessels and 21623 segments met selection criteria for inclusion in the analysis. Patients with a high prevalence of coronary artery disease were included in more than 70% of these studies. The mean values and 95% confidence interval (CI) of sensitivity, specificity, positive predictive value and negative predictive value of 320-slice coronary CT angiography were 96.3% (95% CI: 92.9%, 99.8%), 86.4% (95% CI: 77.8%, 94.9%), 89.6% (95% CI: 85.6%, 93.6%) and 93.2% (95% CI: 84.1%, 100%), at patient-based analysis; 91.8% (95% CI: 85.8%, 97.8%), 95.4% (95% CI: 93.6%, 97.1%), 85.9% (95% CI: 79.7%, 92%) and 97.4% (95% CI: 95.9%, 99.1%), at vessel-based analysis; 86.2% (95% CI: 81.8%, 90.6%), 96.5% (95% CI: 95.2%, 98%), 79.9% (95% CI: 75.3%, 84.6%) and 97.8% (95% CI: 96.7%, 99%), at segment-based analysis, respectively. The mean effective dose of 320-slice coronary CT angiography was 10.5 mSv (95% CI: 6.1, 14.8 mSv). Diagnostic value of 320-slice coronary CT angiography was not affected by different heart rates and calcium scores (p>0.05). This analysis shows that 320-slice coronary CT angiography has high diagnostic value in patients with high coronary artery disease prevalence. Relatively high radiation dose is mainly due to inclusion of patients with high heart rates and without using the advanced dose-reduction techniques, thus, further dose-saving strategies should be implemented to minimise the resultant radiation dose

Optimal Scanning protocol of multislice CT virtual intravascular endoscopy in pre-aortic stent grafting: in vitro phantom study

Objective: To investigate the optimal scanning protocol for multislice computed tomography angiography (MSCT) in pre-aortic stent grafting observed with virtual intravascular endoscopy (VIE).Materials and Methods: The study was performed on a human abdominal aortic phantom which was housed in a perspex container, filled with contrast medium having CT attenuation similar to that used in the patient?s abdominal CT scan. A series of scans were performed on a four-slice multislice CT scanner with the scanning protocols as follows: section thickness of 1.3mm, 3.2mm and 6.5mm, pitch value of 0.875, 1.25 and 1.75 with reconstruction intervals of 50% overlap. The degree of stair-step artifacts was measured at three different locations, superior mesenteric artery (SMA), renal ostium and the normal abdominal aorta. Standard deviation (SD) of the signal intensity measured on surface shaded images was used to determine the image quality. Radiation dose was also recorded in each scanning protocol.Results: The VIE images showed that image quality was not dependant on pitch and section thickness in the visualization of renal ostium and SMA, whereas it was dependant on these two factors at the level of the normal aorta (p<0.05). It was noticed that when section thickness reached 6.5mm the SMA and renal ostia became distorted. Radiation dose measured in 1.3 mm protocols was significantly higher that those measured in other section thicknesses (p<0.05).Conclusion: The scanning protocol of section thickness 3.2mm, pitch 1.25 with a reconstruction interval of 1.6 mm was recommended as it allows optimal visualization of VIE images of aortic ostia, generation of fewer artifacts and less radiation dose

Personalized Three-Dimensional Printed Models in Congenital Heart Disease

Patient-specific three-dimensional (3D) printed models have been increasingly used in cardiology and cardiac surgery, in particular, showing great value in the domain of congenital heart disease (CHD). CHD is characterized by complex cardiac anomalies with disease variations between individuals; thus, it is difficult to obtain comprehensive spatial conceptualization of the cardiac structures based on the current imaging visualizations. 3D printed models derived from patient’s cardiac imaging data overcome this limitation by creating personalized 3D heart models, which not only improve spatial visualization, but also assist preoperative planning and simulation of cardiac procedures, serve as a useful tool in medical education and training, and improve doctor–patient communication. This review article provides an overall view of the clinical applications and usefulness of 3D printed models in CHD. Current limitations and future research directions of 3D printed heart models are highlighted

Inter-hospital transfers and door-to-balloon times for STEMI: a single centre cohort study

Background Key performance indices such as door-to-balloon times have long been recognized as quality metrics in reducing time to care for patients with acute coronary syndromes (ACS). In the situation where patients do not present to a facility capable of 24/7 percutaneous coronary interventions (PCI) delays in time to therapy can exceed the recommendation of 90 minutes or less. This study aimed to evaluate the impact of transfers on performance indices for patients diagnosed with ST-segment elevation myocardial infarction (STEMI). Methods Over a seven month collection period, all patients presenting with symptoms suggestive of ACS and admitted for PCI were studied. Patients were divided into dichotomous groups of direct presentations or transfers from a secondary non-PCI capable hospital with key times recorded, including symptom-onset, first hospital and PCI-capable hospital arrival and balloon inflation times to evaluate time of treatment for STEMI patients. Results Of the 87 patients diagnosed with STEMI, transferred patients experienced statistically significant delays in symptom-onset to the PCI-capable hospital (PCI-H) arrival (215 vs. 95 min, P < 0.001), symptom-onset to balloon inflation (225 vs. 160 min, P = 0.009) and first hospital arrival to balloon inflation times (106 vs. 56 min, P < 0.001). Only 28% (n = 9) of transferred patients underwent balloon inflation within 90 minutes from first hospital arrival, while 60% (n = 19) did within 120 minutes, although all received balloon inflation within 90 minutes from arrival at the PCI-H. After controlling for confounding factors of socio-economic status, presentation date/ time and diagnostic category, transferred patients experienced an average 162% longer delays from symptom-onset to PCI-H door arrival, and 98% longer delays in symptom-onset to balloon inflation; compared to patients who present directly to the PCI-H. No statistically significant differences were noted between transferred and direct patients when measured from PCI-H door-to-balloon times. Conclusions This study shows that transferred patients experience a greater overall system delay, compared to patients who present directly for PCI, significantly increasing their time to treatment and therefore infarct times. Despite the majority of transfers experiencing pre-hospital activation, their treatment hospital arrival to balloon times are no less than direct presenters after controlling for confounding factors, further compounding the overall delay to therapy

Optimization of chest radiographic imaging parameters: a comparison of image quality and entrance skin dose for digital chest radiography systems

We studied the performance of three computed radiography and three direct radiography systems with regard to the image noise and entrance skin dose based on a chest phantom. Images were obtained with kVp of 100, 110, and 120 and mA settings of 1, 2, 4, 8, and 10. Significant differences of image noise were found in these digital chest radiography systems (Pb<0001). Standard deviation was significantly different when the mAs were changed (Pb<001), but it was independent of the kVp values (P=.08–.85). Up to 44% of radiation dose could be saved when kVp was reduced from 120 to 100 kVp without compromising image quality

Effective dose and image optimisation of lateral lumbar spine radiography: a phantom study

Background: To investigate lateral lumbar spine radiography technical parameters for reduction of effective dose whilst maintaining image quality (IQ). Methods: Thirty-six radiograms of an anthropomorphic phantom were acquired using different exposure parameters: source-to-detector distance (SDD) (100, 130 or 150 cm), tube potential (75, 85 or 95 kVp), tube current × exposure time product (4.5, 9, 18 mAs) and additional copper (Cu) filter (no filter, 0.1-, 0.2-, or 0.3-mm thickness. IQ was assessed using an objective approach (contrast-to-noise-ratio [CNR] calculation and magnification measurement) and a perceptual approach (six observers); ED was estimated using the PCXMC 2.0 software. Descriptive statistics, paired t test, and intraclass correlation coefficient (ICC) were used. Results: The highest ED (0.022 mSv) was found with 100 cm SSD, 75 kVp, 18 mAs, and without Cu filter, whilst the highest CNR (7.23) was achieved at 130 cm SSD, 75 kVp, 18 mAs, and without Cu filter. The lowest ED and CNR were generated at 150 cm SDD, 95 kVp, 4.5 mAs, and 0.3-mm Cu filter. All observers identified the relevant anatomical structures on all images with the lowest ED and IQ. The intra-observer (0.61–0.79) and inter-observer (0.55–0.82) ICC ranged from moderate to excellent. Conclusion: All relevant anatomical structures were identified on the lateral lumbar spine radiographs despite using low-dose protocols. The lowest ED (0.002 mSv) was obtained with 150 cm SDD, 95 kVp, 4.5 mAs, and 0.3-mm Cu filter. Further technical and clinical studies are needed to verify these preliminary finding

Patient-specific 3D printed model of biliary ducts with congenital cyst

Background: 3D printing has shown great promise in medical applications, with increasing reports in liver diseases. However, research on 3D printing in biliary disease is limited with lack of studies on validation of model accuracy. In this study, we presented our experience of creating a realistic 3D printed model of biliary ducts with congenital cyst. Measurements of anatomical landmarks were compared at different stages of model generation to determine dimensional accuracy. Methods: Contrast-enhanced computed tomography (CT) images of a patient diagnosed with congenital cyst in the common bile duct with dilated hepatic ducts were used to create the 3D printed model. The 3D printed model was scanned on a 64-slice CT scanner using the similar abdominal CT protocol. Measurements of anatomical structures including common hepatic duct (CHD), right hepatic duct (RHD), left hepatic duct (LHD) and the cyst at left to right and anterior to posterior dimensions were performed and compared between original CT images, the standard tessellation language (STL) image and CT images of the 3D model. Results: The 3D printing model was successfully generated with replication of biliary ducts and cyst. Significant differences in measurements of these landmarks were found between the STL and the original CT images, and the CT images of the 3D printed model and the original CT images (

Atmospheric CO_2 retrieved from ground-based near IR solar spectra

The column-averaged volume mixing ratio (VMR) of CO_2 over Kitt Peak, Arizona, has been retrieved from high-resolution solar absorption spectra obtained with the Fourier transform spectrometer on the McMath telescope. Simultaneous column measurements of CO_2 at ∼6300 cm^−1 and O_2 at ∼7900 cm^−1 were ratioed to minimize systematic errors. These column ratios were then scaled by the mean O_2 VMR (0.2095) to yield column-averaged vmrs of CO_2. These display similar behavior to the Mauna Loa in situ surface measurements. During the period 1977–1995, the column-averaged mixing ratio of CO_2 increased at an average rate of 1.49 ± 0.04 ppmv/yr with seasonal variations of ∼7 ppmv peak-to-peak. Our retrievals demonstrate that this remote technique is capable of precisions better than 0.5%

Recent Update on Radiation Dose Assessment for the State-of-the-Art Coronary Computed Tomography Angiography Protocols

Objectives: This study aimed to measure the absorbed doses in selected organs for prospectively ECG-triggered coronary computed tomography angiography (CCTA) using five different generations CT scanners in a female adult anthropomorphic phantom and to estimate the effective dose (HE). Materials and Methods: Prospectively ECG-triggered CCTA was performed using five commercially available CT scanners: 64-detector-row single source CT (SSCT), 2 × 32-detector-row-dual source CT (DSCT), 2 × 64-detector-row DSCT and 320-detector-row SSCT scanners. Absorbed doses were measured in 34 organs using pre-calibrated optically stimulated luminescence dosimeters (OSLDs) placed inside a standard female adult anthropomorphic phantom. HE was calculated from the measured organ doses and compared to the HE derived from the air kerma-length product (PKL) using the conversion coefficient of 0.014 mSv_mGy-1_cm-1 for the chest region. Results: Both breasts and lungs received the highest radiation dose during CCTA examination. The highest HE was received from 2 × 32-detector-row DSCT scanner (6.06 ± 0.72 mSv), followed by 64-detector-row SSCT (5.60 ± 0.68 and 5.02 ± 0.73 mSv), 2 × 64-detector-row DSCT (1.88 ± 0.25 mSv) and 320-detector-row SSCT (1.34 ± 0.48 mSv) scanners. HE calculated from the measured organ doses were about 38 to 53% higher than the HE derived from the PKL-to-HE conversion factor. Conclusion: The radiation doses received from a prospectively ECG-triggered CCTA are relatively small and are depending on the scanner technology and imaging protocols. HE as low as 1.34 and 1.88 mSv can be achieved in prospectively ECG-triggered CCTA using 320-detectorrow SSCT and 2 × 64-detector-row DSCT scanners