Coronary Computed Tomography Angiography Examination Research Articles

Changes in coronary atherosclerosis, composition, and fractional flow reserve evaluated by coronary computed tomography angiography in patients with type 2 diabetes

BackgroundThe use of coronary computed tomography angiography (CCTA) for noninvasive anatomic detection of coronary artery disease is increasing. Recently, fractional flow reserve (FFR) assessment using routinely acquired CCTA datasets (FFRCT) has been developed. However, there are no reports about changes in coronary atherosclerosis, composition, and FFRCT in patients with type 2 diabetes. MethodsThis prospective, multicenter, observational trial evaluated changes in coronary atherosclerosis after alogliptin therapy in patients with type 2 diabetes. Fifty-one patients with type 2 diabetes who underwent CCTA examination and having intermediate coronary artery stenosis were treated with 25 mg of alogliptin. After 48 weeks, CCTA examination was repeated. The primary endpoint was changes in FFRCT, and the secondary endpoint was changes in total atheroma volume (TAV) from the baseline to the 48-week follow-up. ResultsThe FFRCT decreased from the baseline to follow-up, but not significantly. A significant increase in TAV (from 658.5 mm3 to 668.9 mm3, p = 0.048) was observed. Vessel volume tended to increase, whereas percentage atheroma volume and lumen volume did not change. A significant negative correlation was observed between percentage change in TAV and change in FFRCT (r = −0.185, p = 0.048). A significant increase in calcified plaques (p = 0.01) and a decrease in intermediate-attenuation plaques (p = 0.006) was observed. ConclusionsIn Japanese patients with diabetes and intermediate coronary artery stenosis, alogliptin could not improve FFRCT or reduce atheroma volume, whereas the plaque composition changed. A progression of atheroma volume was associated with a reduction in FFRCT.

Diagnostic Performance of a Novel Coronary CT Angiography Algorithm: Prospective Multicenter Validation of an Intracycle CT Motion Correction Algorithm for Diagnostic Accuracy.

Motion artifact can reduce the diagnostic accuracy of coronary CT angiography (CCTA) for coronary artery disease (CAD). The purpose of this study was to compare the diagnostic performance of an algorithm dedicated to correcting coronary motion artifact with the performance of standard reconstruction methods in a prospective international multicenter study. Patients referred for clinically indicated invasive coronary angiography (ICA) for suspected CAD prospectively underwent an investigational CCTA examination free from heart rate-lowering medications before they underwent ICA. Blinded core laboratory interpretations of motion-corrected and standard reconstructions for obstructive CAD (≥ 50% stenosis) were compared with ICA findings. Segments unevaluable owing to artifact were considered obstructive. The primary endpoint was per-subject diagnostic accuracy of the intracycle motion correction algorithm for obstructive CAD found at ICA. Among 230 patients who underwent CCTA with the motion correction algorithm and standard reconstruction, 92 (40.0%) had obstructive CAD on the basis of ICA findings. At a mean heart rate of 68.0 ± 11.7 beats/min, the motion correction algorithm reduced the number of nondiagnostic scans compared with standard reconstruction (20.4% vs 34.8%; p < 0.001). Diagnostic accuracy for obstructive CAD with the motion correction algorithm (62%; 95% CI, 56-68%) was not significantly different from that of standard reconstruction on a per-subject basis (59%; 95% CI, 53-66%; p = 0.28) but was superior on a per-vessel basis: 77% (95% CI, 74-80%) versus 72% (95% CI, 69-75%) (p = 0.02). The motion correction algorithm was superior in subgroups of patients with severely obstructive (≥ 70%) stenosis, heart rate ≥ 70 beats/min, and vessels in the atrioventricular groove. The motion correction algorithm studied reduces artifacts and improves diagnostic performance for obstructive CAD on a per-vessel basis and in selected subgroups on a per-subject basis.

ESTIMATION OF DIAGNOSTIC REFERENCE LEVELS FOR CT CORONAROGRAPHY IN SLOVAKIA.

The coronary CT angiography (CCTA) is a frequent diagnostic method connected with large variability of effective dose. Therefore, it is the type of examination where optimization is very important and the use of a national diagnostic reference level (DRL) recommended. In Slovakia the DRL for interventional radiology examinations until now fails. The objective of our study was to propose the national DRL for CCTA examinations in Slovak Republic, on the basis of a cross-sectional multicenter study, performed in four departments of radiology. The study was realized in 2014-16 in a sample of 1725 patients undergoing CCTA examination. The proposed DRL expressed by CTDIVOL is 45 mGy and of DLP is 510 mGy cm.

Coronary CT Angiography: Use in Patients With Chest Pain Presenting to Emergency Departments.

Previously published reports have shown that coronary CT angiography (CCTA) is a more efficient method of diagnosis than myocardial perfusion imaging (MPI) and stress echocardiography for patients presenting to emergency departments (EDs) with acute chest pain. In light of this evidence, the objective of this study was to examine recent trends in the use of these techniques in EDs. The nationwide Medicare Part B databases for 2006-2015 were the data source. The Current Procedural Terminology, version 4, codes for CCTA, MPI, and stress echocardiography were selected. Medicare place-of-service codes were used to determine procedure volumes in EDs. Medicare specialty codes were used to ascertain how many of these examinations were interpreted by radiologists, cardiologists, and other physicians as a group. From 2006 to 2015, there was essentially no change in the number of MPI examinations performed in EDs for patients using Medicare (22,342 in 2006, 22,338 in 2015) or in the number of stress echocardiograms (3544 in 2006, 3520 in 2015). By contrast, the number of CCTA examinations increased rapidly, from 126 in 2006 to 1919 in 2015 (compound annual growth rate, 35%). Despite this rapid growth, patients in EDs underwent 11.6 times as many MPI as CCTA examinations in 2015. In that last year of the study, radiologists interpreted 78% of ED MPI and 83% of ED CCTA examinations. Use of CCTA in EDs has increased rapidly, but far more MPI examinations are still being performed. This finding suggests that recently acquired evidence is not yet being fully acted upon.

Assessment of Effective Dose Associated with Coronary Computed Tomography Angiography in Isfahan Province, Iran

Computed tomography coronary angiography (CTCA) has generated a great interest over the past two decades, due to its high diagnostic accuracy and efficacy in the assessment of patients having coronary artery disease. This method is associated with high radiation dose and this has raised serious concerns in the literature. Effective dose (E) is a single parameter meant to reflect the relative risk from exposure to ionizing radiation. Therefore, it is necessary to calculate this parameter to indicate ionizing radiation relative risk. The aim of this study was to calculate the effective dose from 64-slice CTCA in Isfahan. To calculate the effective dose, an ionization chamber and a body phantom with diameter of 32 cm and length of 15 cm were used. CTCA radiation conditions commonly used in two centers were applied for this work. For all scans, computed tomography volume dose index (CTDIv), dose-length product (DLP), and effective dose were obtained using dose-length-product method. The obtained CTDIv, DLP, and effective dose were compared in two centers, and mean, maximum, and minimum values of effective dose for heart coronary CT angiography (CCTA) examinations and calcium score were compared with other studies. The amount of average, maximum, and minimum effective doses for heart CCTA examinations in two centers are 4.65 ± 0.06, 6.0489, and 3.492 mSv, respectively, and for calcium score test are, 1.04 ± 0.04, 2.155, and 0.98 mSv, respectively. CTDIv, DLP, and effective dose values did not show any significant difference in two centers. Although the effective dose of CTCA and calcium score was lower than that of other studies, it is reasonable to reduce the effective dose to the minimum possible value to reduce the risk of cancer associated with ionizing radiation. The results of this study can be used to introduce the effective dose as a local diagnostic reference dose (DRL) for CTCA examinations in Isfahan Province.

Image Quality of Prospectively ECG-Triggered Coronary CT Angiography in Heart Transplant Recipients.

Cardiac allograft vasculopathy (CAV) is among the top causes of death 1 year after heart transplantation (HTx). Coronary CT angiography (CTA) is a potential alternative to invasive imaging in the diagnosis of CAV. However, the higher heart rate (HR) of HTx recipients prompts the use of retrospective ECG-gating, which is associated with higher radiation dose, a major concern in this patient population. Therefore, we sought to evaluate the feasibility and image quality of low-radiation-dose prospectively ECG-triggered coronary CTA in HTx recipients. In total, 1270 coronary segments were evaluated in 50 HTx recipients and 50 matched control subjects who did not undergo HTx. The control subjects were selected from our clinical database and were matched for age, sex, body mass index, HR, and coronary dominance. Scans were performed using 256-MDCT with prospective ECG-triggering. The degree of motion artifacts was evaluated on a per-segment basis on a 4-point Likert-type scale. The median HR was 74.0 beats/min (interquartile range [IQR], 67.8-79.3 beats/min) in the HTx group and 73.0 beats/min (IQR, 68.5-80.0 beats/min) in the matched control group (p = 0.58). In the HTx group, more segments had diagnostic image quality compared with the control group (624/662 [94.3%] vs 504/608 [82.9%]; p < 0.001). The mean effective radiation dose was low in both groups (3.7 mSv [IQR, 2.4-4.3 mSv] in the HTx group vs 4.3 mSv [IQR, 2.6-4.3 mSv] in the control group; p = 0.24). Prospectively ECG-triggered coronary CTA examinations of HTx recipients yielded diagnostic image quality with low radiation dose. Coronary CTA is a promising noninvasive alternative to routine catheterization during follow-up of HTx recipients to diagnose CAV.

Mid-term graft patency of right versus left internal mammary artery as arterial conduit usage for left anterior descending artery revascularisation: Insights from a single-centre study of propensity-matched data

BackgroundPrevious studies reported the strategy of in situ skeletonised right internal mammary artery (RIMA) grafting to the left anterior descending artery (LAD). However, few reports have focused on assessing RIMA graft patency rate after grafting to the LAD. This study aimed to assess mid-term graft patency of in situ skeletonised RIMA grafting to the LAD versus in situ skeletonised left internal mammary artery (LIMA) grafting to the LAD in a single-centre propensity-matched study. Materials and methodsAfter propensity score matching, 185 pairs of patients who received first, scheduled, isolated off-pump coronary artery bypass grafting (OPCAB) surgery were assigned to either a RIMA group (patients who received retrosternal crossover in situ skeletonised RIMA-LAD grafting with additional conduits grafting) or a LIMA group (patients who received in situ skeletonised LIMA-LAD grafting with additional conduits grafting). The primary endpoint was mid-term internal mammary artery (IMA) graft failure after grafting to the LAD and was determined by coronary computed tomography angiography examination. The secondary endpoints were mid-term all-cause mortality and the composite mid-term clinical outcome. ResultsThe graft patency rate of in situ skeletonised RIMA-LAD graft was not inferior to in situ skeletonised LIMA-LAD graft during a follow-up period of 36.6 ± 12.1 months (97.2% vs. 96.6%, p = 0.752). Kaplan-Meier curves showed a similar cumulative IMA graft failure between the two groups (χ2 = 0.092, Log-rank p = 0.762). And Cox regression analysis revealed that grouping was not an independent factor for follow-up IMA graft failure after grafting to the LAD (HR = 0.93, 95% CI: 0.68–2.13). Additionally, Kaplan-Meier curves showed similar cumulative survival free from adverse events between the two groups (χ2 = 2.365, p = 0.124, respectively). ConclusionsRevascularisation of the LAD using a skeletonised RIMA resulted in excellent mid-term graft patency and clinical outcomes.

An investigation of correlation between left coronary bifurcation angle and hemodynamic changes in coronary stenosis by coronary computed tomography angiography-derived computational fluid dynamics.

To investigate the correlation between left coronary bifurcation angle and coronary stenosis as assessed by coronary computed tomography angiography (CCTA)-generated computational fluid dynamics (CFD) analysis when compared to the CCTA analysis of coronary lumen stenosis and plaque lesion length with invasive coronary angiography (ICA) as the reference method. Thirty patients (22 males, mean age: 59±6.9 years) with calcified plaques at the left coronary artery were included in the study with all patients undergoing CCTA and ICA examinations. CFD simulation was performed to analyze hemodynamic changes to the left coronary artery models in terms of wall shear stress, wall pressure and flow velocity, with findings correlated to the coronary stenosis and degree of bifurcation angle. Calcified plaque length was measured in the left coronary artery with diagnostic value compared to that from coronary lumen and bifurcation angle assessments. Of 26 significant stenosis at left anterior descending (LAD) and 13 at left circumflex (LCx) on CCTA, only 14 and 5 of them were confirmed to be >50% stenosis at LAD and LCx respectively on ICA, resulting in sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 100%, 52%, 49% and 100%. The mean plaque length was measured 5.3±3.6 and 4.4±1.9 mm at LAD and LCx, respectively, with diagnostic sensitivity, specificity, PPV and NPV being 92.8%, 46.7%, 61.9% and 87.5% for extensively calcified plaques. The mean bifurcation angle was measured 83.9±13.6º and 83.8±13.3º on CCTA and ICA, respectively, with no significant difference (P=0.98). The corresponding sensitivity, specificity, PPV and NPV were 100%, 78.6%, 84.2% and 100% based on bifurcation angle measurement on CCTA, 100%, 73.3%, 78.9% and 100% based on bifurcation angle measurements on ICA, respectively. Wall shear stress was noted to increase in the LAD and LCx models with significant stenosis and wider angulation (>80º), but demonstrated little or no change in most of the coronary models with no significant stenosis and narrower angulation (<80º). This study further clarifies the relationship between left coronary bifurcation angle and significant stenosis, with angulation measurement serving as a more accurate approach than coronary lumen assessment or plaque lesion length for determining significant coronary stenosis. Left coronary bifurcation angle is suggested to be incorporated into coronary artery disease (CAD) assessment when diagnosing significant CAD.

Estimation and comparison of the radiation effective dose during coronary computed tomography angiography examinations on single-source 64-MDCT and dual-source 128-MDCT

Goal. To estimate and compare the radiation dose associated with coronary computed tomography angiography (CCTA) examinations on two multi-detector CT scanners (MDCT), 64-MDCT and 128-MDCT, in daily practice. Methods. Scan parameters of 90 patients undergoing retrospective electrocardiographic gating spiral CCTA exam were recorded during a period on a single-source 64-MDCT and a dual-source 128-MDCT, and average scan parameters were derived that were used for dosimetry. The computed tomography dose index (CTDI) with a pencil ionisation chamber and polymethyl methacrylate body phantom with diameter of 32 cm was measured on both scanners. The dose–length product (DLP) was calculated and the DLP to effective dose conversion factor (for chest scan at 120 kV of 0.014 mSv mGy–1 cm–1) was used to estimate effective dose (ED). Results. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 128-MDCT were 64 (5) (beats min–1), 161 (10) (mm), 0.26, 47 (12) (mGy), 769 (212) (mGy cm) and 10.3 (3.1) (mSv), respectively [mean (one standard deviation)]. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 64-MDCT were 60 (7) (beats min–1), 172 (14) (mm), 0.2, 60 (6) (mGy), 1068 (98) (mGy cm) and 14.9 (1.4) (mSv), respectively. Conclusion. Our results indicated that the CTDIv, DLP and the effective dose with 128-MDCT is significantly lower than with 64-MDCT (p < 0.05). As differences between the exposure parameter mAs on two CT scanners was not significant (p > 0.05) and the kV was constant for both scanners (120 kV), the differences resulted from a shorter scan length on the 128-MDCT and use of a higher pitch factor (0.26 and 0.2 in the 128-MDCT and 64-MDCT, respectively). Comparison with other published studies confirms the findings and indicates methods for reducing patient dose.

A pilot study on the noninvasive fluid hemodynamic investigation of coronary plaque

Objective: To characterize the hemodynamic force towards coronary plaque based on noninvasive coronary computed tomographic angiography and to investigate its relationship with plaque features and stenosis severity by computational fluid dynamics. Methods: Twenty-six patients underwent invasive fractional flow reserve measurement following coronary computed tomography angiography examination from March to September 2016 were retrospectively included. Computational fluid dynamics was applied and wall shear stress (WSS) and axial plaque stress (APS), which extracted the axial component of hemodynamic stress acting on stenotic lesions, were calculated based on the results of noninvasive coronary computed tomographic angiography. Plaque analysis was performed to elucidate plaque features and relative plaque burden. The fluid dynamics distributions in lesions with different stenosis severity were investigated. Results: Thirty-one coronary plaques with satisfactory imaging quality were analyzed, there were 11 (35.5%) dominant low WSS (<1 Pa) lesion and 20 high WSS lesion (64.5%), 8(25.8%) net retrograde APS lesion and 23(74.2%) anterograde lesion. Plaque volume was (78.5±48.6) mm(3) and plaque burden was (69.1±12.1)% in the low WSS group, which was(60.5±57.3) mm(3), and(57.5±14.0)%, respectively in the high WSS group, the plaque burden was significantly higher in the low WSS group than in the high WSS group (P=0.028), while the percentage of calcified plaque, fibrotic plaque and lipid core volume were similar between the two groups (P>0.05). Plaque volume was (79.7±69.1) mm(3) and plaque burden was(68.7±13.7)% in the group with anterograde-dominant APS plaque, which was(61.7±24.9)mm(3), and(68.9±10.4)%, respectively in the net retrograde APS lesion group (P>0.05). Percentage of lipid core area was significantly higher in the anterograde lesion group than in the retrograde lesion group ((25.1±18.1)% vs.(10.8±12.7)%, P=0.049). Both WSS and APS were significant higher in the severe obstructive coronary stenosis group than in non-severe obstructive coronary stenosis group (P<0.05). Although there was no difference in WSS between functional coronary ischemia group and non-functional coronary ischemia group ( (13.3±8.7) Pa vs. (12.5±14.2) Pa, P>0.05), the distribution of APS was different between the functional coronary ischemia group and non-functional coronary ischemia group ((1 698.8±652.6) Pa vs. (981.4±787.5) Pa, P<0.05). Conclusion: WSS and APS can uniquely characterize the stenotic segment and has a strong relationship with lesion geometry. APS may be related to the necrotic core plaque and functional coronary ischemia. Clinical application of these hemodynamic and geometric indices may be helpful to assess the future risk of plaque progress and plaque rupture, which will be helpful on determining respective treatment strategy for patients with coronary artery disease.

Evaluation of Coronary Artery Disease and Coronary Anomalies with a Handheld Smartphone.

The purpose of this study was to determine the diagnostic accuracy of an iPhone for evaluation of the coronary arteries on coronary CT angiography (CTA) in comparison to a standard clinical workstation. Fifty coronary CTA exams were selected to include a range of normal and abnormal cases including both coronary artery disease (CAD) of varying severity and coronary artery anomalies. Two cardiac radiologists reviewed each exam on a standard clinical workstation initially and then on an iPhone 6 after a washout period. Coronary stenosis was evaluated on a 4-point scale and presence of coronary anomalies was recorded. Two additional cardiac radiologists reviewed all cases in consensus on the standard workstation and these results were used as the reference standard. When reader results were compared to the reference standard, there was no significant difference in agreement for per-vessel stenosis scores using either the iPhone or standard clinical workstation. The intraobserver intertechnology agreement on a per-vessel basis for obstructive CAD were 97.4% (299/307, kappa=0.777) and 97.5% (317/325, kappa=0.804) for the two readers. All cases of coronary anomalies were identified by both readers regardless of the device used. Coronary CTA examinations can be interpreted on a smartphone with diagnostic accuracy comparable to a standard workstation. 3D visualization app on the iPhone may facilitate urgent coronary CTA review when a workstation is not available.

Feasibility of low-dose coronary computed tomographic angiography used in atrial fibrillation patients

Objective: The diagnosis of coronary artery disease (CAD) in atrial fibrillation (AF) patients using coronary computed tomography angiography (CCTA) requires a large exposure dosage or repeated examinations. This study evaluates the feasibility of using low-dose CCTA in the double prospectively ECG-triggered high-pitch spiral acquisition mode (Double Flash Spiral mode).Methods: Twenty-eight AF patients with suspected CAD were recruited. Double Flash Spiral mode (tube voltage 100 kVp) and iterative reconstruction was used for CCTA examination. Two radiologists cross-evaluated the CCTA image quality. The effective radiation dose was measured for each patient.Results: Twenty-eight AF patients (10 female, 18 male, mean age 68.8 ± 13.9 y, body mass index 24.3 ± 2.3 kg/cm2) were recruited and 337 artery segments were evaluated. In total, 98.5% (332/337) of the coronary artery segments and 96.4% (27/28) of the AF patients were rated as diagnostically evaluable. Of these 27 diagnosable patients, 17 patients (63%) were diagnosed with multi-vessel stenosis. Besides, 5 of 28 patients (17.9%) have left atrial appendage thrombus. The quality of the integrated image was significantly better than either of the individual first or the second scans, based on segments (P < 0.001) and patients (P < 0.05). The mean effective radiation dose was 1.5 mSv ±0.4 mSv.Conclusions: Using the Double Flash Spiral mode at low radiation dose (mean 1.5 mSv), 98.5% of the coronary segments and 96.4% of the scans were of sufficient diagnostic quality.

Characteristics Detected on Computed Tomography Angiography Predict Coronary Artery Plaque Progression in Non-Culprit Lesions.

ObjectiveThis study sought to determine whether variables detected on coronary computed tomography angiography (CCTA) would predict plaque progression in non-culprit lesions (NCL).Materials and MethodsIn this single-center trial, we analyzed 103 consecutive patients who were undergoing CCTA and percutaneous coronary intervention (PCI) for culprit lesions. Follow-up CCTA was scheduled 12 months after the PCI, and all patients were followed for 3 years after their second CCTA examination. High-risk plaque features and epicardial adipose tissue (EAT) volume were assessed by CCTA. Each NCL stenosis grade was compared visually between two CCTA scans to detect plaque progression, and patients were stratified into two groups based on this. Logistic regression analysis was used to evaluate the factors that were independently associated with plaque progression in NCLs. Time-to-event curves were compared using the log-rank statistic.ResultsOverall, 34 of 103 patients exhibited NCL plaque progression (33%). Logistic regression analyses showed that the NCL progression was associated with a history of ST-elevated myocardial infarction (odds ratio [OR] = 5.855, 95% confidence interval [CI] = 1.391–24.635, p = 0.016), follow-up low-density lipoprotein cholesterol level (OR = 6.832, 95% CI = 2.103–22.200, p = 0.001), baseline low-attenuation plaque (OR = 7.311, 95% CI = 1.242–43.028, p = 0.028) and EAT (OR = 1.015, 95% CI = 1.000–1.029, p = 0.044). Following the second CCTA examination, major adverse cardiac events (MACEs) were observed in 12 patients, and NCL plaque progression was significantly associated with future MACEs (log rank p = 0.006).ConclusionNoninvasive assessment of NCLs by CCTA has potential prognostic value.

Influence of increased epicardial adipose tissue volume on 1-year in-stent restenosis in patients who received coronary stent implantation.

BackgroundEpicardial adipose tissue (EAT) is significantly associated with the formation and composition of coronary atherosclerotic plaque, cardiac events and the clinical prognosis of coronary heart disease. But, whether increased EAT deposition may affect the incidence of in-stent restenosis (ISR) is currently unclear. This study used coronary computed tomography angiography (CCTA) as a mean to investigate whether increased EAT volume was associated with ISR.MethodsA total of 364 patients who underwent 64-slice CCTA examination for the evaluation of suspected coronary artery disease, and subsequently underwent percutaneous coronary intervention (PCI) for the first time, and then accepted coronary angiography (CA) follow-up for ISR examination in one year, were retrospectively included in this study. EAT volume was measured by CCTA examination. CA follow-up was obtained between 9 and 15 months. ISR was defined as ≥ 50% luminal diameter narrowing of the stent segment or peri-stent segment. EAT volume was compared between patients with and without ISR and additional well-known predictors of ISR were compared.ResultsEAT volume was significantly increased in patients with ISR compared with those without ISR (154.5 ± 74.6 mL vs. 131.0 ± 52.2 mL, P < 0.001). The relation between ISR and EAT volume remained significant after adjustment for conventional cardiovascular risk factors and angiographic parameters.ConclusionsEAT volume was related with ISR and may provide additional information for future ISR.

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

ObjectivesThis 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 MethodsProspectively 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.ResultsBoth 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.ConclusionThe 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-detector-row SSCT and 2 × 64-detector-row DSCT scanners.

Thoracic Aortic Strain is Irrelevant Regarding Endograft Sizing in Most Young Patients

The introduction of electrocardiogram gating in computed tomography (CT) angiography imaging of aortic disease raised questions whether diameters measured on diastolic images can lead to the undersizing of aortic endografts. As previous studies suggested that young patients may have the highest risk of an unintended undersize, the aim of our study was to analyze the strain of the thoracic aorta in a young patient cohort. We assessed the descending aorta of 52 patients (35 men, mean age 41.1±7.3years) who underwent coronary CT angiography (CCTA) with suspected coronary artery disease. To reduce radiation dose, native calcium score scans triggered on late systole were compared with diastolic phase CCTA images. Cross-section areas were measured, and effective diameters were derived at 3 levels of the visible segment of the descending aorta (P1, P2, and P3) in systole and diastole. Aortic pulsatility (mm, dsystolic-ddiastolic) and strain (%, [dsystolic-ddiastolic]/ddiastolic) were calculated at each level. All measurements were performed 3 times by 2 independent readers to evaluate interreader and intrareader reproducibility. A total of 936 measurements were performed. Significant differences were found between systolic and diastolic diameters at each location (all P<0.001). Average aortic pulsatility was 1.5±0.6mm at P1, 1.6±0.7mm at P2, and 1.7±0.7mm at P3, with a corresponding aortic strain of 6.7 ±3.1% at P1, 7.4 ±3.5% at P2, and 8.1 ±3.6% at P3. The differences between the strain of the measurement levels were not significant (P=0.344). Aortic strain and pulsatility did not show significant correlation with pulse pressure (P=0.693), patient age (P=0.649), or other anamnestic data. Intraclass correlation coefficient was in the range of 0.95-0.96 for interobserver and in the range of 0.95-0.97 for intraobserver analysis. This study shows that descending aortic strain can be measured precisely and reliably on images of routine CCTA examinations with native scans acquired during systole. We demonstrated that young adults have an aortic strain of 6.7-8.1%. As the average thoracic aortic strain was still lower than the recommended prosthesis oversize of 10%, routine use of systolic phase imaging cannot be recommended: it has no clinical benefit for the vast majority of the patients but increases the risk of motion artefacts. We also demonstrated that large interindividual differences are present in the scale of thoracic aortic strain, a phenomenon that needs further investigations to be fully understood.

Coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) imaging in the assessment of patients presenting with chest pain suspected for acute coronary syndrome.

Acute chest pain is an important clinical challenge and a major reason for presentation to the emergency department. Although multiple imaging techniques are available to assess patients with suspected acute coronary syndrome (ACS), considerable interest has been focused on the use of non-invasive imaging options as coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR). According to several recent evidences, CCTA has been shown to represent a useful tool to rapidly and accurately diagnose coronary artery disease (CAD) in patients with low to intermediate cardiovascular risk. CCTA examination has the unique ability to non-invasively depict the coronary anatomy, not only allowing visualization of the lumen of the arteries in order to detect severe stenosis or occlusion responsible of myocardial ischemia, but also allows the assessment of coronary artery wall by demonstrating the presence or absence of CAD. However, routine CCTA is not able to differentiate ischemic from non-ischemic chest pain in patients with known CAD and it does not provide any functional assessment of the heart. Conversely, CMR is considered the gold standard in the evaluation of morphology, function, viability and tissue characterization of the heart. CMR offers a wide range of tools for diagnosing myocardial infarction (MI) at least at the same time of the elevation of cardiac troponin values, differentiating infarct tissue and ischemic myocardium from normal myocardium or mimicking conditions, and distinguishing between new and old ischemic events. In high-risk patients, with acute and chronic manifestations of CAD, CMR may be preferable to CCTA, since it would allow detection, differential diagnosis, prognostic evaluation and management of MI.

Correlations Between the Contrast Density Gradient along the Coronary Stents and Functional Significance of In-stent Restenosis

Abstract Introduction: Coronary artery disease (CAD) is the leading cause of death worldwide and is associated with a significant socio-economic impact. In many cases, patients are treated with implanted coronary stents that carry a significant risk for reobstruction. The aim of our study was to evaluate the importance of coronary computed tomography angiography (CCTA) in evaluating the significance of in-stent restenosis lesions and for establishing the indication for reintervention in these cases. Materials and methods: We evaluated 25 patients who underwent CCTA examination. We determined the contrast density, expressed in Hounsfield units at two levels, proximal and distal to the stent. Results: There were no statistically significant differences between the study groups in terms of gender (41.17% females in Group 1 vs. 37.5% in Group 2, p = 1), presence of hypertension (41.17% in Group 1 vs. 62.5% in Group 2, p = 0.31), smoking status (41.17% in Group 1 vs. 37.5% in Group 2, p = 0.31), incidence of dyslipidemia (47.05% vs. 50%, p = 1) and diabetes mellitus (35.29% vs. 0%, p = 0.31). However, the age of the study population was significantly higher in the groups with significant ISR (58.94 ± 8.35 vs. 47.25 ± 11.2, p = 0.02). Patients who showed significant angiographic in-stent stenosis (more than 70%) were found to have a higher transluminal attenuation gradient, compared with those with less severe lesions (14.5 ± 5.4 vs. 5.14 ± 2.4, p = 0.02). Conclusions: The transluminal attenuation gradient, assessed by CCTA is a non-invasive-derived parameter that can help the clinician to determine the right time for revascularization in case of in-stent restenosis.

Improved image-quality consistency in coronary CT angiography using a test-bolus-based individually tailored contrast medium injection protocol

To develop and validate a test bolus (TB)-based quantitative model to create an individualised contrast medium injection protocol for use at coronary computed tomography angiography (CCTA) to improve patient-to-patient uniformity of intracoronary attenuation. In the model-building phase, 175 patients who underwent CCTA using a traditional contrast medium injection protocol were recruited. A personalised injection equation was proposed according to the relationship between aortic enhancement and the haemodynamic parameters obtained from the TB. In the model-validation phase, a target aortic enhancement of 350 HU was set. Two hundred and fifteen additional CCTA examinations were performed using the proposed personalised injection model. Comparisons of inter-individual variability between the traditional and the proposed personalised injection protocol were performed. In the model-building phase, a high positive correlation between aortic enhancement and the haemodynamic parameters obtained from the TB was found. As a result, a personalised injection equation was determined using linear regression. In the model-validation phase, the average aortic enhancement was 350.5 HU, without significant differences from the preset level. Using the TB-based personalised injection protocol, inter-individual variability of aortic enhancement was significantly reduced (71.8 versus 38.9 HU, p<0.001) and patients who were scanned at 100kVp had a reduction in the average contrast medium flow rate from 4.1 to 3.2ml/s (p<0.001). The proposed TB-based injection protocol can achieve a desired preset and stable aortic enhancement.

Remote reading of coronary CTA exams using a tablet computer: utility for stenosis assessment and identification of coronary anomalies

The feasibility of remote reading of coronary CT examinations on tablet computers has not been evaluated. The purpose of this study is to evaluate the accuracy of coronary CT angiography reading using an iPad compared to standard 3D workstations. Fifty coronary CT angiography exams, including a spectrum of coronary artery disease and anatomic variants, were reviewed. Coronary CT angiography exams were interpreted by two readers independently on an iPad application (Siemens Webviewer) and a clinical 3D workstation at sessions 2weeks apart. Studies were scored per vessel for severity of stenosis on a 0-3 scale (0 none, 1 <50%, 2 ≥50-69%, 3 ≥70%). Coronary anomalies were recorded. A consensus read by two experienced cardiac imagers was used as the reference standard. Level of agreement with the reference for iPad and 3D workstations was compared. Multivariate logistic regression was used to analyze the relationship between agreement and display type and to adjust for inter-reader differences. For both readers, there was no significant difference in agreement with the reference standard for per-vessel stenosis scores using either the 3D workstation or the iPad. In a multivariable logistic regression analysis including reader, workstation, and vessel as co-variates, there was no significant association between workstation type or reader and agreement with the reference standard (p > 0.05). Both readers identified 100% of coronary anomalies using each technique. Reading of coronary CT angiography examinations on the iPad had no influence on stenosis assessment compared to the standard clinical workstation.