Prospectively ECG-triggered high-pitch coronary CT angiography at 70 kVp with 30 mL contrast agent: An intraindividual comparison with sequential scanning at 120 kVp with 60 mL contrast agent

PurposeTo investigate image quality, radiation dose, and diagnostic efficiency of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) at 70 kVp with 30 mL contrast agent intra-individually compared with routine CCTA protocol.Materials and methodsOne hundred and thirty eight patients with suspected coronary artery disease, body mass index (BMI) ≤ 25 kg/m² and heart rate (HR) ≤ 70 beats per minute (bpm) underwent prospectively ECG-triggered high-pitch CCTA at 70 kVp and 30 mL contrast agent (protocol A) and prospectively ECG-triggered sequential scanning at 120 kVp and 60 mL contrast medium (protocol B). Objective and subjective image quality, radiation doses, and diagnostic accuracy were evaluated and compared between the two protocols.ResultsHigher CT attenuation, higher noise, lower signal-to-noise ratios (SNRs) and lower contrast-to-noise ratios (CNRs) were found in protocol A than in protocol B (P < 0.001). However, image quality of protocol A were diagnostic. In patients with BMI < 23 kg/m² or HR < 60 bpm, subjective image quality scores of some coronary arteries in protocol A were not significantly different from protocol B (P > 0.05). Effective dose in protocol A has reduced by 96.7% compared with protocol B (P < 0.001). No significant differences were found for diagnostic accuracy between the two protocols on a per-segment (P = 0.513), per-vessel (P = 0.317) and per-patient (P = 0.125) basis.ConclusionsProspectively ECG-triggered high-pitch CCTA at 70 kVp with 30 mL contrast agent can reduce radiation dose but maintain image quality and high diagnostic accuracy in a selected, non-obese population.     

Influence of irregular heart rhythm on radiation exposure,image quality and diagnostic impact of cardiac computed tomography angiography in 4,339 patients. Data from the German Cardiac Computed Tomography Registry

BackgroundCoronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD).AimTo investigate whether irregular heart rhythm including atrial fibrillation and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA.MethodsTwelve tertiary care centers with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2014, 4339 examinations were analysed in patients who underwent clinically indicated coronary CTA for suspected CAD. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed.ResultsOf 4339 patients in total, 260 (6.0%) had irregular heart rhythm, whereas the remaining 4079 (94.0%) had stable sinus rhythm. Patients with irregular heart rhythm were older (63.2 ± 12.5yrs versus 58.6 ± 11.4yrs. p < 0.001), exhibited a higher rate of pathologic stress tests before CTA (37.1% versus 26.1%, p < 0.01) and higher heart rates during CTA compared to those with sinus rhythm (62.5 ± 11.6bpm versus 58.9 ± 8.5bpm, p < 0.001). Both contrast media exposure and radiation exposure were significantly higher in patients with irregular heart rhythm (90 mL (95%CI = 80–110 mL) versus 80 mL (95%CI = 70–90 mL) and 6.2 mSv (95%CI = 2.5–11.7) versus 3.3 mSv (95%CI = 1.7–6.9), p < 0.001 for both). Coronary CTA excluded significant CAD less frequently in patients with irregular heart rhythm (32.9% versus 44.8%, p < 0.001). This was attributed to the higher rate of examinations with at least one non-diagnostic coronary segment in patients with irregular heart rhythm (10.8% versus 4.6%, p < 0.001). Subsequent invasive angiography could be avoided in 47.2% of patients with irregular heart rhythm compared to 52.9% of patients with sinus rhythm (p = NS), whereas downstream stress testing was recommended in 3.2% of patients with irregular heart rhythm versus 4.0% of patients with sinus rhythm (p = NS).ConclusionA significant number of patients scheduled for coronary CTA have irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent coronary CTA examinations with at least one non-diagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures.     

Comparison of different strategies of ivabradine premedication for heart rate reduction before coronary computed tomography angiography

ObjectiveThe aim of this study was to assess the effectiveness and safety of different strategies of ivabradine therapy by comparing the effects on heart rate (HR), blood pressure (BP), and image quality of coronary CT angiography (CTA).MethodsA total of 192 consecutive patients were randomly assigned to 3 groups of oral premedication with ivabradine 15 mg (single dose), 10 mg (single dose), and 5 mg twice daily for 5 days, prospectively. Patients using HR-lowering drugs and patients with β-blockade contraindication were excluded. The target HR was 65 beats/min. In addition 5 to 10 mg of intravenous metoprolol was administered to the patients at the CT unit, if required. The systolic and diastolic blood BP values and the HRs were recorded. Image quality was assessed for 8 of 15 coronary segments with a 4-point grading scale. Results were compared with the Kruskal-Wallis test, one-way ANOVA, and χ² test.ResultsReductions in mean HR after the treatment were 18 ± 6, 14 ± 4, and 17 ± 7 beats/min for groups 1, 2, and 3, respectively. With the total additional therapies, 81.3%, 67.2%, and 84.3% of the patients achieved HR < 65 beats/min in groups 1, 2, and 3, respectively. The mean BP values before coronary CTA were not significantly changed except for patients in group 2. Unacceptable (score 0) image quality was obtained in only 4.5%, 10.2%, and 4.2% of all the coronary segments, in groups 1, 2, and 3, respectively.ConclusionsOur study indicates that coronary CTA with premedication with oral ivabradine in all 3 strategies is safe and effective in reducing HR, in particular with a β-blockade combination. All 3 ivabradine regimes may be an alternative strategy for HR lowering in patients undergoing coronary CTA. Ivabradine 15 mg (single dose) and ivabradine 5 mg twice daily for 5 days are superior to the ivabradine 10-mg single-dose regime for HR lowering without adjunctive intravenous β-blocker usage.     

Right ventricular dysfunction by computed tomography associates with outcomes in severe aortic stenosis patients undergoing transcatheter aortic valve replacement

BackgroundAlthough cardiac computed tomography angiography (CCTA) assessment of right ventricular dysfunction (RVD) is feasible, the incremental prognostic value remains uncertain in patients undergoing transcatheter aortic valve replacement (TAVR) evaluation. This study sought to determine the incremental clinical utility of RVD identification by CCTA while accounting for clinical and echocardiographic parameters.MethodsPatients who underwent multiphasic ECG-gated functional CCTA using dual-source system for routine TAVR planning were evaluated. Biphasic contrast protocol injection allowed for biventricular contrast enhancement. CCTA-based RVD was defined as right ventricular ejection fraction (RVEF) ?< ?50%. The association of CCTA-RVD with all-cause mortality and the composite outcome of death or heart failure hospitalization after TAVR was evaluated and examined for its incremental utility beyond clinical risk assessment and echocardiographic parameters.ResultsA total of 502 patients were included (median [IQR] age, 82 [77 to 87] years; 56% men) with a median follow-up of 22 [16 to 32] months. Importantly, 126 (25%) patients were identified as having RVD by CCTA that was not identified by echocardiography. CCTA-defined RVD predicted death and the composite outcome in both univariate analyses (HR for mortality, 2.15; 95% CI, 1.44–3.22; p ?< ?0.001; HR for composite outcome, 2.11; 95% CI, 1.48–3.01; p ?< ?0.001) and in multivariate models that included clinical risk factors and echocardiographic findings (HR for mortality, 1.74; 95% CI, 1.11–2.74; p ?= ?0.02; HR for composite outcome, 1.63; 95% CI, 1.09–2.44; p ?= ?0.02).ConclusionsFunctional CCTA assessment pre-TAVR correctly identified 25% of patients with RVD that was not evident on 2D echocardiography. The presence of RVD on CCTA independently associates with clinical outcomes post-TAVR.     

Ballooning-induced bradycardia during carotid stenting in primary stenosis and restenosis

Introduction We compared the incidence of intraprocedural bradycardia and hypotension during carotid artery stenting in patients with primary carotid artery stenosis and those with prior ipsilateral carotid endarterectomy.Methods A total of 213 carotid stenting procedures were performed in our institution in a 4-year period. The mean degree of stenosis was 78% (range 60–99%). Of these 213 procedures, 43 were performed for carotid restenosis, 9 after stenting and 34 after endarterectomy, and 170 for primary stenosis. Atropine was selectively administrated if patients suffered bradycardia (a decrease in heart rate to <50% or an absolute heart rate of <40 bpm) or hypotension (systolic blood pressure <90 mmHg). We compared the group of patients with primary stenosis (n=170) and the group of patients with restenosis after carotid endarterectomy (n=34) in relation to intraprocedural hypotension or bradycardia/need for atropine administration.Results Hypotension occurred in 49 patients with primary stenosis and 2 patients with restenosis. The difference was statistically significant. Atropine was administered for bradycardia to 58 patients with primary stenosis and 3 patients with restenosis. The difference was statistically significant.Conclusion Intraprocedural bradycardia and hypotension occur more frequently in patients with primary carotid artery stenosis.     

Evaluation of the effectiveness of oral Beta-blockade in patients for coronary computed tomographic angiography

OBJECTIVE: To determine the effectiveness of oral medications in lowering the resting heart rate (HR) for coronary computed tomographic angiography (CTA). BACKGROUND: The protocol of premedication for cardiac CTA is variable in terms of type, dose, route, and timing of administration. METHODS: Nursing records were retrospectively reviewed in 238 consecutive patients having coronary CTA and 217 patients evaluated for type and amount of oral medication administered. The HR on arrival to computed tomography (CT) and 30 and 60 minutes after medication was noted. RESULTS: One hundred twenty-three patients (56.6%) had a mean HR of 78.3 +/- 9.4 beats per minute (bpm) on arrival and were given medication. One hundred fourteen patients (92.6%) were given 50 mg of oral metoprolol, with the remaining receiving 25 to 100 mg and 1 patient receiving 30 mg of oral diltiazem. Sixty-eight patients (55.2%) were monitored for less than 1 hour and had a mean HR of 73.1 +/- 5.1 bpm on arrival, a 9.8 +/- 4.7-bpm decrease in HR at 30 minutes, and an HR of 56.5 +/- 7.2 bpm during CT. Thirty-nine patients (31.7%) had a mean HR of 81.3 +/- 7.2 bpm on arrival, a 9.8 +/- 7.4-bpm decrease in HR at 30 minutes, a 16.9 +/- 6.3-bpm decrease in HR at 60 minutes, and an HR of 59.8 +/- 4.8 bpm during CT. Sixteen patients were monitored for more than 1 hour, followed by intravenous metoprolol. These patients had a baseline HR of 93.5 +/- 8.9 bpm, a 13.1 +/- 6.4-bpm decrease in HR at 30 minutes, a 15.9 +/- 6.8-bpm decrease in HR at 60 minutes, and an HR of 68.1 +/- 7.9 bpm during CT. There were no complications due to metoprolol. CONCLUSION: Oral metoprolol given 1 hour before cardiac CT effectively and safely lowers the resting HR in most patients.     

Efficacy of pre-scan beta-blockade and impact of heart rate on image quality in patients undergoing coronary multidetector computed tomography angiography

OBJECTIVE: While beta-blockers are routinely administered to patients prior to coronary computed tomography angiography (CTA), their effectiveness is unknown. We therefore assessed the efficacy of beta-blockade with regards to heart rate (HR) control and image quality in an unselected patient cohort. METHODS: We studied 150 consecutive patients (104 men/46 female; mean age, 56+/-13 years) referred for coronary CTA. Intravenous metoprolol (5-20mg) was administered to patients with a HR >65 beats per minute (bpm). The goal HR was defined as an average HR <65 bpm without a single measurement above 68 bpm. RESULTS: Overall, 45% (68/150) of patients met the HR criteria for beta-blocker administration of which 76% (52/68) received metoprolol (mean dose 12+/-10mg). Of the 52 patients who received beta-blocker versus the 98 who did not, 18 (35%) versus 62 (64%) patients achieved the goal HR, respectively. All patients who achieved the target HR had an evaluable CTA while five patients who did not achieve the target HR had at least one non-evaluable coronary artery due to motion artifact. There was also a significant reduction in any motion artifact among those who achieved the goal HR as compared to those who did not (p=0.001). Logistic regression revealed an increase in the odds of stair step artifact of 11.6% (95% CI: 2.4% decrease, 27.5% increase) per 1 bpm increase in the standard deviation of scan HR. CONCLUSION: Overall, efficacy of beta-blocker administration to reach target HR is limited. Improvements in CT scanner temporal resolution are mandatory to achieve consistently high image quality independent of HR and beta-blocker administration.     

Adequate image quality with reduced radiation dose in prospectively triggered coronary CTA compared with retrospective techniques

The goal of our study was to compare a prospective triggering (PT) CT technique with retrospectively gated (RG) CT techniques in coronary computed tomographic angiograms (CCTA) with respect to image quality and radiation dose. Sixty consecutive patients were enrolled. CCTAs using the RG technique were obtained with a dual-source 64-slice CT system in 40 patients, using ECG-triggered tube current modulation, with either a broad pulsing window at 30–80% of the RR interval (group RGb, 20 patients, heart rate > 70 bpm) or a small pulsing window at 70% (group RGs, 20 patients, heart rate < 70 bpm). The other 20 patients underwent CCTA using the PT technique on a 128-slice CT system (group PT, heart rate < 70 bpm). All images were evaluated by two observers for quality on a three-point scale, with 1 being excellent and 3 being insufficient. The effective radiation dose was calculated for each patient. The average image quality score was 1.5 ± 0.6 for PT, 1.35 ± 0.5 for RGs and 1.65 ± 0.5 for RGb. The mean effective dose for RGb was 9 ± 4 mSv, for RGs 7 ± 3 mSv and for PT 3 ± 1 mSv. This represents a 57% dose reduction for PT compared with RGs and a 67% dose reduction for PT compared with RGb. In conclusion, in selected patients CCTA with the PT technique offers adequate image quality with a significantly lower radiation dose compared with CCTA using RG techniques. None of the authors have financial or other kinds of interests that might pose a conflict of interest in connection with this article.     

Design of a 3D printed coronary artery model for CT optimization

IntroductionTo design a custom phantom of the coronary arteries to optimize CT coronary angiography (CCTA) protocols.MethodsCharacteristics of the left and right coronary arteries (mean Hounsfield Unit (HU) values and diameters) were collected from consecutive CCTA examinations (n = 43). Four different materials (two mixtures of glycerine, gelatine and water, pig hearts, Ecoflex? silicone) were scanned inside a Lungman phantom using the CCTA protocol to find the closest model to in vivo data. A 3D printed model of the coronary artery tree was created using CCTA data by exporting a CT volume rendering into Autodesk Meshmixer? software. The model was placed in an acid bath for 5 h, then covered in Ecoflex?, which was removed after drying. Both the Ecoflex? and pig heart were later filled with a mixture of contrast (Visipaque 320 mg I/ml), NaCl and gelatin and scanned with different levels of tube current and iterative reconstruction (ASiR-V). Objective (HU, noise and size (vessel diameter) and subjective analysis were performed on all scans.ResultsThe gelatine mixtures had HU values of 130 and 129, Ecoflex? 65 and the pig heart 56. At the different mA/ASiR-V levels the contrast filled Ecoflex? had a mean HU 318 ± 4, noise 47±7HU and diameter of 4.4 mm. The pig heart had a mean HU of 209 ± 5, noise 38±4HU and a diameter of 4.4 mm. With increasing iterative reconstruction level the visualisation of the pig heart arteries decreased so no measurements could be performed.ConclusionThe use of a 3D printed model of the arteries and casting with the Ecoflex? silicone is the most suitable solution for a custom-designed phantom.Implications for practiceCustom designed phantoms using 3D printing technology enable cost effective optimisation of CT protocols.     

Interpretability of coronary CT angiography performed with a novel whole-heart coverage high-definition CT scanner in 300 consecutive patients with coronary artery bypass grafts

AimsCoronary CT angiography (CCTA) is an accurate non-invasive tool for the evaluation of coronary artery bypass graft (CABG). However, inability to sustain a long breath-hold, high heart rate (HR) and atrial fibrillation may affect image quality. Moreover, radiation exposure is still a matter of some concern. A scanner combining 0.23-mm spatial resolution, new iterative reconstruction and fast gantry rotation time has been recently introduced in the clinical field. The aims of our study were to evaluate interpretability, radiation exposure and diagnostic accuracy of CCTA performed with the latest generation of cardiac-CT scanners compared to invasive coronary angiography (ICA) in the assessment of bypass grafts, and non-grafted and post-anastomotic native coronary arteries.Methods and resultsWe prospectively enrolled 300 patients undergoing clinically indicated CCTA with a 16-cm z-axis coverage, 256-detector rows, and 0.28-sec gantry rotation time scanner. Coronary artery and graft interpretability, image quality and effective dose (ED) were assessed in all patients and diagnostic accuracy was evaluated in a subgroup of 100 patients who underwent ICA.Mean HR during the scan was 69.6 ± 10.8. Sinus rhythm was present in 118 patients with HR < 75 bpm and in 112 patients with HR ≥ 75 bpm, while 70 patients had atrial fibrillation. CABG interpretability was 100%. Compared to ICA, CCTA was able to correctly detecting occlusions or significant stenoses of all CABG segments. Overall interpretability of native coronary segments was 95.6%. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of coronary arteries were 98.3%, 97.4%, 93.1%, 99.3% and 96.5%, respectively. The diagnostic accuracy in a patient based analysis was 95.2%. Mean ED was 3.14 ± 1.7 mSv.ConclusionsThe novel whole-heart coverage CT scanner allows to evaluating CABG and native coronary arteries with excellent interpretability and low radiation exposure even in the presence of unfavorable heart rhythm.     

Effect of injection duration on contrast enhancement during cardiac computed tomography angiography in newborns and infants

IntroductionTo investigate how changing the injection duration at cardiac computed tomography angiography (CCTA) affects contrast enhancement in newborns and infants.MethodsIncluded were 142 newborns and infants with confirmed congenital heart disease who underwent CCTA between January 2015 and December 2018. In group 1 (n = 71 patients), the injection duration was 8 s; in group 2 (n = 71) it was 16 s. Our findings were assessed by one-to-one matching analysis to estimate the propensity score of each patient. We compare the CT number for the pulmonary artery (PA), ascending aorta (AAO), left superior vena cava (SVC), AAO and PA enhancement ratio, and the scores for visualization between the two groups.ResultsIn group 1, median CT number and ranges was 345 (211–591) HU in the AAO, 324 (213–567) HU in the PA, and 62 (1–70) HU in the SVC. These values were 465 (308–669) HU, 467 (295–638) HU, and 234 (67–443) HU, respectively, in group 2 (p < 0.05). The median score for volume-rendering visualization on 3D images of the CCTA was 2 in group 1 and 3 in group 2; the score for visualization of the left SVC of the maximum intensity projection images was 2 in group 1 and 3 in group 2 (p < 0.05). The CT number for the AAO and PA enhancement ratio was 15.2 in group 1 and 9.2 in group 2 (p < 0.05).ConclusionThe 16-sec injection protocol yielded significantly higher CT numbers for the AAO, PA, and the SVC than the 8-sec injection protocol; the visualization scores were also significantly higher in group 2.Implications for practiceIn newborns and infants, the longer injection time for CCTA yields stable and higher contrast enhancement at identical CM concentrations.     

Safety and efficacy of oral ivabradine as a heart rate-reducing agent in patients undergoing CT coronary angiography

Objective

To investigate the role of oral ivabradine as a heart rate reducing agent in patients undergoing CT coronary angiography (CTCA). Despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm. Ivabradine is a selective inhibitor of the I_f current, which primarily contributes to sinus node pacemaker activity, and has no significant direct cardiovascular effects such as reduction of blood pressure, cardiac contractility or impairment of cardiac conduction.

Methods

We investigated 100 consecutive patients who had been referred for CTCA for the evaluation of suspected coronary artery disease (CAD). Patients were randomised to receive either of the following two pre-medication protocols: oral metorprolol or oral ivabradine.

Results

Ivabradine was significantly more effective than metorprolol in lowering the heart rate; the mean percentage reduction in heart rate with ivabradine vs metorpolol was 23.89+6.95% vs 15.20+4.50%, respectively (p=0.0001). Metoprolol significantly lowered both systolic and diastolic blood pressure while ivabradine did not. The requirement of additional doses to achieve a target heart rate of <65 beats per min was also significantly more frequent with metoprolol.

Conclusion

Ivabradine is a potentially attractive alternative to currently used drugs for reduction of heart rate in patients undergoing CTCA.Since the introduction of CT coronary angiography (CTCA) as a non-invasive tool for coronary artery imaging, its clinical utility has been established in various studies [1-3]. However, the presence of motion artefacts often prevents optimal reconstruction of individual coronary arteries, prompting use of pharmacological interventions (primarily β-blockers) during scanning to enhance image quality [4,5]. A target heart rate of 65 beats per min (bpm) or less provides optimum image quality in most cases [6,7]. Though calcium channel-blockers have also been used as alternatives to β-blockers [8], there still exists a subset of patients in whom the administration of these rate-lowering drugs may be hazardous (e.g. those with baseline blood pressure <100–110 mmHg, severe left ventricular dysfunction, peripheral vascular disease or severe obstructive airway disease). Moreover, despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm [9-11].There is a clear need for assessment of the potential role of alternative rate-lowering drugs in patients undergoing CTCA. Ivabradine, a novel heart rate-lowering agent, is a selective and specific inhibitor of the I_f current, which is one of the most important ionic currents for regulating pacemaker activity in the sinoatrial (SA) node [12-14]. This is primarily a mixed Na⁺–K⁺ inward current activated by hyperpolarisation and modulated by the autonomic nervous system, and ivabradine acts by selectively inhibiting the pacemaker I_f current and slowing the diastolic depolarisation slope of SA node cells, reducing both resting and exercise heart rate. Moreover, ivabradine inhibits the I_f current at concentrations that do not affect other cardiac ionic currents, resulting in a lack of haemodynamic effects such as reduction of blood pressure or cardiac contractility, which is often a limitation with β-blockers. It has a good safety profile without any effects on atrioventricular conduction, corrected QT interval and peripheral vasomotion, and there is no rebound effect with drug cessation or tolerance with prolonged use.We investigated the safety and efficacy of oral ivabradine as a heart rate-lowering agent in patients undergoing CTCA at our institute. The aims of the study were (1) to assess the efficacy of ivabradine in achieving adequate heart rate control (defined as target heart rate <65 bpm), (2) to compare the differences (if any) between ivabradine and the β-blocker metoprolol in achieving target heart rate prior to CTCA and (3) to compare any difference in numbers of patients requiring additional doses of drugs prior to achieving the target heart rate.     

Impact of age on coronary artery plaque progression and clinical outcome: A PARADIGM substudy

BackgroundThe association of age with coronary plaque dynamics is not well characterized by coronary computed tomography angiography (CCTA).MethodsFrom a multinational registry of patients who underwent serial CCTA, 1153 subjects (61 ± 5 years old, 61.1% male) were analyzed. Annualized volume changes of total, fibrous, fibrofatty, necrotic core, and dense calcification plaque components of the whole heart were compared by age quartile groups. Clinical events, a composite of all-cause death, acute coronary syndrome, and any revascularization after 30 days of the initial CCTA, were also analyzed. Random forest analysis was used to define the relative importance of age on plaque progression.ResultsWith a 3.3-years’ median interval between the two CCTA, the median annual volume changes of total plaque in each age quartile group was 7.8, 10.5, 10.8, and 12.1 mm³/year and for dense calcification, 2.5, 4.6, 5.4, and 7.1 mm³/year, both of which demonstrated a tendency to increase by age (p-for-trend = 0.001 and < 0.001, respectively). However, this tendency was not observed in any other plaque components. The annual volume changes of total plaque and dense calcification were also significantly different in the propensity score-matched lowest age quartile group versus the other age groups as was the composite clinical event (log-rank p = 0.003). In random forest analysis, age had comparable importance in the total plaque volume progression as other traditional factors.ConclusionsThe rate of whole-heart plaque progression and dense calcification increases depending on age. Age is a significant factor in plaque growth, the importance of which is comparable to other traditional risk factors.Clinical trial registrationURL: http://www.clinicaltrials.gov. Unique identifiers: NCT02803411.     

Diagnostic performance of free-breathing coronary computed tomography angiography without heart rate control using 16-cm z-coverage CT with motion-correction algorithm

ObjectivesTo evaluate the feasibility of coronary computed tomography angiography (CCTA) in patients with free-breathing using 16-cm z-coverage CT with motion correction algorithm.Methods616 patients underwent CCTA without heart rate control. 325 examinations were performed during breath-holding (group A), and the remaining 291 were performed during free-breathing (group B). The image quality scores were defined as 1 (excellent), 2 (good), 3 (adequate), and 4 (poor). 22 patients in group A and 24 in group B underwent invasive coronary angiography (ICA) after CCTA within two weeks. The image quality score, diagnostic accuracy using ICA as reference, signal-to-noise ratio (SNR), and effective dose (ED) were compared between the two groups.ResultsMean heart rate during scanning was 70.8 ± 13.8 bpm in group A and 70.7 ± 13.2 bpm in group B (P = .950). No significant differences were observed in SNR and image quality score (1.49 ± 0.62 vs. 1.53 ± 0.67; P = .647) between the breath-holding and free-breathing groups. ED (1.99 ± 0.83 mSv vs. 2.01 ± 0.88 mSv) was not significantly different between the two groups (P = .975). In a segment-based analysis, the sensitivity, specificity and diagnostic accuracy in the detection of coronary stenosis of more than 50% were 82.1%, 96.8% and 92.2%, respectively in the breath-holding group and 82.2%, 96.6% and 92.2%, respectively in the free-breathing group with no significant differences for these parameters between the two groups.ConclusionsCCTA for patients without heart rate control and during free-breathing using 16-cm z-coverage CT with motion correction algorithm showed no significant difference in image quality and diagnostic performance compared with CCTA during breath-holding.     

Comparative effectiveness of coronary CT angiography vs stress cardiac imaging in patients following hospital admission for chest pain work-up: The Prospective First Evaluation in Chest Pain (PERFECT) Trial

Background

Because the frequency of cardiac event rates is low among chest pain patients following either performance of coronary CT angiography (CCTA) or stress testing, there is a need to better assess how these tests influence the central management decisions that follow from cardiac testing. The present study was performed to assess the relative impact of CCTA vs stress testing on medical therapies and downstream resource utilization among patients admitted for the work-up of chest pain.

Methods

The admitted patients were randomized in a 1:1 ratio to either cardiac imaging stress test or CCTA. Primary outcomes were time to discharge, change in medication usage, and frequency of downstream testing, cardiac interventions, and cardiovascular re-hospitalizations. We randomized 411 patients, 205 to stress testing, and 206 to CCTA.

Results

There were no differences in time to discharge or initiation of new cardiac medications at discharge. At 1 year follow-up, there was no difference in the number of patients who underwent cardiovascular downstream tests in the CCTA vs stress test patients (21% vs 15%, P = .1) or cardiovascular hospitalizations (14% vs 16%, P = .5). However, there was a higher frequency of invasive angiography in the CCTA group (11% vs 2%, P = .001) and percutaneous coronary interventions (6% vs 0%, P < .001).

Conclusions

Randomization of hospitalized patients admitted for chest pain work-up to either CCTA or to stress testing resulted in similar discharge times, change in medical therapies at discharge, frequency of downstream noninvasive testing, and repeat hospitalizations. However, a higher frequency of invasive coronary angiography and revascularization procedures were performed in the CCTA arm. (ClinicalTrials.gov number, NCT01604655.)

     

The direct costs of coronary CT angiography relative to contrast-enhanced thoracic CT: Time-driven activity-based costing

BackgroundCoronary CT angiography (CCTA) and contrast-enhanced thoracic CT (CECT) are distinctly different diagnostic procedures that involve intravenous contrast-enhanced CT of the chest. The technical component of these procedures is reimbursed at the same rate by the Centers for Medicare and Medicaid Services (CMS). This study tests the hypothesis that the direct costs of performing these exams are significantly different.MethodsDirect costs for both procedures were measured using a time-driven activity-based costing (TDABC) model. The exams were segmented into four phases: preparation, scanning, post-scan monitoring, and image processing. Room occupancy and direct labor times were collected for scans of 54 patients (28 CCTA and 26 CECT studies), in seven medical facilities within the USA and used to impute labor and equipment cost. Contrast material costs were measured directly. Cost differences between the exams were analyzed for significance and variability.ResultsMean CCTA duration was 3.2 times longer than CECT (121 and 37 ​min, respectively. p ​< ​0.01). Mean CCTA direct costs were 3.4 times those of CECT ($189.52 and $55.28, respectively, p ​< ​0.01). Both labor and capital equipment costs for CCTA were significantly more expensive (6.5 and 1.8-fold greater, respectively, p ​< ​0.001). Segmented by procedural phase, CCTA was both longer and more expensive for each (p ​< ​0.01). Mean direct costs for CCTA exceeded the standard CMS technical reimbursement of $182.25 without accounting for indirect or overhead costs.ConclusionThe direct cost of performing CCTA is significantly higher than CECT, and thus reimbursement schedules that treat these procedures similarly undervalue the resources required to perform CCTA and possibly decrease access to the procedure.     

The effect of patient and imaging characteristics on coronary CT angiography assessed pericoronary adipose tissue attenuation and gradient

BackgroundCoronary CT angiography (CCTA) pericoronary adipose tissue (PCAT) markers are promising indicators of inflammation.ObjectiveTo determine the effect of patient and imaging parameters on the associations between non-calcified plaque (NCP) and PCAT attenuation and gradient.MethodsThis was a single-center, retrospective analysis of consecutive patients with stable chest pain who underwent CCTA and had zero calcium scores. CCTA images were evaluated for the presence of NCP, obstructive stenosis, segment stenosis and involvement score (SSS, SIS), and high-risk plaque (HRP). PCAT markers were assessed using semi-automated software. Uni- and multivariable regression models correcting for patient and imaging characteristics between plaque and PCAT markers were evaluated.ResultsOverall, 1652 patients had zero calcium score (mean age: 51 years ?± ?11 [SD], 871 women); PCAT attenuation values ranged between ?123 HU and ?51 HU, and 649 patients had plaque. In univariable analysis, the presence of NCP, SSS, SIS, and HRP were associated with PCAT attenuation (2, 1, 1, 6 HU; respectively; p ?< ?.001 all); while obstructive stenosis was not (1 HU, p ?= ?.58). In multivariable analysis, none of the plaque markers were associated with PCAT attenuation (0 HU p ?= ?.93, 0 HU p ?= ?.39, 1 HU p ?= ?.18, 2 HU p ?= ?.10, 1 HU p ?= ?.71, respectively), while patient and imaging characteristics showed significant associations, such as: male sex (1 HU, p ?= ?.003), heart rate [1/min] (?0.2 HU, p ?< ?.001), 120 ?kVp (8 HU, p ?< ?.001) and pixel spacing [mm³] (32 HU, p ?< ?.001). Similar results were observed for PCAT gradient.ConclusionPCAT markers were significantly associated with NCP, however the associations did not persist following correction for patient and imaging characteristics.     

Influence of heart rate on diagnostic accuracy and image quality of 16-slice CT coronary angiography: comparison of multisegment and halfscan reconstruction approaches

The lower the heart rate the better image quality in multislice computed tomography (MSCT) coronary angiography. We prospectively assessed the influence of heart rate on per-patient diagnostic accuracy and image quality of MSCT coronary angiography and compared adaptive multisegment and standard halfscan reconstruction. A consecutive cohort of 126 patients scheduled to undergo conventional coronary angiography was examined with 16-slice CT. For all heart rate groups, per-patient diagnostic accuracy was significantly higher for multisegment than halfscan reconstruction with values of 95 vs. 79% (p < 0.05, <65 bpm, 38 patients), 85 vs. 66% (p < 0.05, 65–74 bpm, 47 patients), and 78% vs. 41% (p < 0.001, >74 bpm, 41 patients). Differences in diagnostic accuracy between adjacent heart rate groups were only significant for halfscan reconstruction for the comparison between the 65–74 and >74 bpm group (p < 0.05). The vessel lengths free of motion artifacts were significantly longer with multisegment reconstruction in all heart rate groups and for all coronary arteries (p < 0.005). For noninvasive MSCT coronary angiography, both per-patient diagnostic accuracy and image quality decline with increasing heart rate, and multisegment reconstruction at high heart rates yields similar results as standard halfscan reconstruction at low heart rates.     

Dynamic CT Myocardial Perfusion Imaging in Patients without Obstructive Coronary Artery Disease: Quantification of Myocardial Blood Flow according to Varied Heart Rate Increments after Stress

ObjectiveThe present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease.Materials and MethodsWe retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded.ResultsThe median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5–6.8) mSv. The median global MBF of all subjects was 156.4 (139.8–180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm.ConclusionThe global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.     

Optimal image reconstruction intervals for non-invasive coronary angiography with 64-slice CT

The reconstruction intervals providing best image quality for non-invasive coronary angiography with 64-slice computed tomography (CT) were evaluated. Contrast-enhanced, retrospectively electrocardiography (ECG)-gated 64-slice CT coronary angiography was performed in 80 patients (47 male, 33 female; mean age 62.1±10.6 years). Thirteen data sets were reconstructed in 5% increments from 20 to 80% of the R-R interval. Depending on the average heart rate during scanning, patients were grouped as <65 bpm (n=49) and ≥65 bpm (n=31). Two blinded and independent readers assessed the image quality of each coronary segment with a diameter ≥1.5 mm using the following scores: 1, no motion artifacts; 2, minor artifacts; 3, moderate artifacts; 4, severe artifacts; and 5, not evaluative. The average heart rate was 63.3±13.1 bpm (range 38–102). Acceptable image quality (scores 1–3) was achieved in 99.1% of all coronary segments (1,162/1,172; mean image quality score 1.55±0.77) in the best reconstruction interval. Best image quality was found at 60% and 65% of the R-R interval for all patients and for each heart rate subgroup, whereas motion artifacts occurred significantly more often (P<0.01) at other reconstruction intervals. At heart rates <65 bpm, acceptable image quality was found in all coronary segments at 60%. At heart rates ≥65 bpm, the whole coronary artery tree could be visualized with acceptable image quality in 87% (27/31) of the patients at 60%, while ten segments in four patients were rated as non-diagnostic (scores 4–5) at any reconstruction interval. In conclusion, 64-slice CT coronary angiography provides best overall image quality in mid-diastole. At heart rates <65 bpm, diagnostic image quality of all coronary segments can be obtained at a single reconstruction interval of 60%.