Evaluation Of Coronary Artery Stenosis Research Articles

Evaluation of Instantaneous Wave-Free Ratio and Fractional Flow Reserve in Severe Aortic Valve Stenosis.

The optimal functional evaluation of coronary artery stenosis in patients with severe aortic stenosis (AS) has not been established. The objective of the study was to evaluate the instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) in patients with and without severe AS. We retrospectively investigated 395 lesions in 293 patients with severe AS and 2257 lesions in 1882 patients without severe AS between 2010 and 2022 from a subgroup of the Interventional Cardiology Research In-Cooperation Society FFR Registry. All patients had FFR values, and iFR was analyzed post hoc using dedicated software only in lesions with adequate resting pressure curves (311 lesions in patients with severe AS and 2257 lesions in patients with nonsevere AS). The incidence of iFR ≤0.89 was 66.6% and 31.8% (P<0.001), while the incidence of FFR ≤0.80 was 45.3% and 43.9% (P=0.60) in the severe AS group and the nonsevere AS group, respectively. In the severe AS group, most lesions (95.2%) with iFR >0.89 had FFR >0.80, while 36.2% of lesions with iFR ≤0.89 had FFR >0.80. During a median follow-up of 2 years, FFR ≤0.80 was significantly associated with deferred lesion failure (adjusted hazard ratio, 2.71 [95% CI, 1.08-6.80]; P=0.034), while iFR ≤0.89 showed no prognostic value (adjusted hazard ratio, 1.31 [95% CI, 0.47-3.60]; P=0.60) in the severe AS group. Lesions with iFR ≤0.89 and FFR >0.80, in particular, were not associated with a higher rate of deferred lesion failure at 3 years compared with lesions with iFR >0.89 (15.4% versus 17.0%; P=0.58). This study suggested that FFR appears to be less affected by the presence of severe AS and is more associated with prognosis. iFR may overestimate the functional severity of coronary artery disease without prognostic significance, yet it can be useful for excluding significant stenosis in patients with severe AS.

Functional evaluation of intracranial atherosclerotic stenosis by pressure ratio measurements

BackgroundFractional flow reserve is widely used for the functional evaluation of coronary artery stenosis. Some studies have similarly used the translesional pressure ratio measurements for the functional evaluation of intracranial atherosclerotic stenosis. In this paper, we aimed to investigate the relationship between pressure ratio and cerebral tissue perfusion by MR perfusion imaging and provided a non-invasive method for evaluating the functional significance of intracranial atherosclerotic stenosis. MethodsA total of 18 consecutive patients with intracranial atherosclerotic stenosis patients including 19 stenotic vessels were recruited. The pressure was measured using a pressure guidewire, the pressure ratio before and after the endovascular intervention was calculated and compared with the severity of diameter stenosis and perfusion-derived MR (the time to maximum tissure residue function (Tmax)). Moreover, the DSA-derived pressure ratio was computed using a novel computational fluid dynamics-based model, termed CFD-PR, and was compared with the actual pressure ratio to assess its diagnostic accuracy. ResultsThe pressure ratio increased after percutaneous transluminal angioplasty or stenting, while the correlation between pressure ratio and diameter stenosis was not significant. The pressure ratio was negatively correlated with Tmax (r = −0.73, P < 0.01), and a 95% confidence interval for the cutoff value of pressure ratio = 0.67 (95% confidence interval: 0.58–0.76) was suggested. There was a good correlation (mean = 0.02, Spearman's correlation coefficient r = 0.908, P < 0.001) and agreement (limits of agreement: -0.157 to 0.196, P = 0.954) between CFD-PR and the actual pressure ratio. ConclusionsThis exploratory study indicates the pressure ratio may correlate with the perfusion status. The pressure ratio can be calculated through a non-invasive method using a computational fluid dynamics-based method.

Magnetocardiography Using a Novel Analysis System (Cardioflux) in ED Observation Unit Chest Pain Patients – A Feasibility Study

SUMMARY Background: Cardiovascular disease is currently the leading cause of death in the United States and is the second most common chief complaint among Emergency Department (ED) patients. Magnetocardiography (MCG) has emerged as a viable, non-invasive option for the evaluation of coronary artery stenosis. Cardioflux (CF) is a novel MCG imaging and analysis system. This study aims to evaluate the feasibility of using MCG using CF (MCG-CF) in our Emergency Department Observation Unit (EDOU). Methods: This is a single-center, retrospective, observational study of ED patients placed in the EDOU to evaluate of symptoms of possible cardiac ischemia from July 1, 2017 to October 31, 2017 to evaluate if they would have been eligible for MCG-CF scanning. Results: Of the 225 patients that met inclusion criteria, 69% were eligible for an MCG-CF scan (n = 156). The average patient was 55 years, 54% were women and 59% were Black. The most common exclusion was having a BMI of greater than or equal to 35kg/m2 making up 86% of exclusions. Conclusions: This feasibility study demonstrates that most patients in our EDOU are eligible for a MCG-CF scan.

Factors associated with discordance between fractional flow reserve and resting full-cycle ratio

BackgroundResting full-cycle ratio (RFR), a non-hyperemic pressure ratio, is alternative to fractional flow reserve (FFR) for the evaluation of coronary artery stenoses. Although FFR and RFR results are often discordant using the cut-off values (0.80 and 0.89), factors associated with the discordance are unclear. The aim of this study was to explore factors related to the discordant results. MethodsWe performed FFR and RFR measurements in a total of 408 vessels with intermediate coronary artery stenosis in 277 patients. Positive FFR and RFR were defined based on the cut-off values of 0.80 and 0.89. The discordance was determined as positive FFR and negative RFR (FFR ≤0.80 and RFR >0.89) or negative FFR and positive RFR (FFR >0.80 and RFR ≤0.89). ResultsOverall, FFR and RFR were significantly correlated (r = 0.76, p < 0.001), while positive FFR and negative RFR and negative FFR and positive RFR were observed in 44 (10.8%) and 45 (11.0%) of 408 vessels, respectively. Smaller body surface area, diabetes, chronic kidney disease including hemodialysis, severe aortic stenosis, higher E/e', and lower left ventricular ejection fraction on echocardiography, and lower hemoglobin and higher brain natriuretic peptide levels were identified as factors associated with the negative FFR and positive RFR discordance. ConclusionsDiscordant results between FFR and RFR were often found in more than 20% of vessels with intermediate coronary stenosis. Clinical characteristics such as renal function, heart failure, and anemia may be considered in clinical decision-making when using FFR and RFR.

Efficacy of fractional flow reserve measurement in the assessment of stenotic lesions of coronary artery

Context: The decision to perform an intervention on a narrowed coronary artery depends on the ischemia caused by the stenosis. The indication for intervention usually applies to cases with ≥70% stenosis of vascular diameter because of the risk of myocardial ischemia. Aims: To define the efficacy of fractional flow reserve (FFR) measurement in the evaluation of coronary artery stenosis. Methods: This prospective study was conducted on patients with intermediate coronary artery stenosis who underwent quantitative coronary angiography after coronary computed tomography angiography. Results: The study population consisted of 46 men and 26 women with a mean age of 66.0 ± 12.9 years. FFR was significantly correlated with the grade of angina pectoris (r = – 0.387; p&lt;0.01) and showed a negative correlation with percentage diameter stenosis (r = – 0.241, p&lt;0.05) and a positive correlation with the minimal lumen diameter (MLD; r = 0.377, p&lt;0.05). The cut-off value to predict positive FFR was &gt;55.62% diameter stenosis and MLD ≤ 1.08 mm. FFR ≤ 0.80 indicating intervention and FFR &gt; 0.80 indicating medical therapy were observed in 56.9% and 43.1% of the cases, respectively. No major cardiac complications occurred during 12 months of follow-up in both groups. Conclusions: FFR measurements for intermediate stenosis of the coronary artery should be used to evaluate the possibility of myocardial ischaemia. If FFR is not available, a cut-off point of &gt;55.62% diameter stenosis or MLD ≤ 1.08 mm can be used to predict the FFR results.

Diagnostic Performance of Angiography-Based Fractional Flow Reserve for Functional Evaluation of Coronary Artery Stenosis.

Background: A new method for calculating fraction flow reserve (FFR) without pressure-wire (angiography-derived FFR) based on invasive coronary angiography (ICA) images can be used to evaluate the functional problems of coronary stenosis.Objective: The aim of this study was to assess the diagnostic performance of a novel method of calculating the FFR compared to wire-based FFR using retrospectively collected data from patients with stable angina.Methods: Three hundred patients with stable angina pectoris who underwent ICA and FFR measurement were included in this study. Two ICA images with projections >25° apart at the end-diastolic frame were selected for 3D reconstruction. Then, the contrast frame count was performed in an angiographic run to calculate the flow velocity. Based on the segmented vessel, calculated velocity, and aortic pressure, AccuFFRangio distribution was calculated through the pressure drop equation.Results: Using FFR ≤ 0.8 as a reference, we evaluated AccuFFRangio performance for 300 patients with its accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Comparison of AccuFFRangio with wire-measured FFR resulted in an area under the curve (AUC) of 0.954 (per-vessel, p < 0.0001). Accuracy for AccuFFRangio was 93.7% for Pa set from measurement and 87% for Pa = 100 mmHg in this clinical study. Overall sensitivity, specificity, PPV, and NPV for per-vessel were 90, 95, 86.7, 96.3, and 57.5, 97.7, 90.2, 86.3%, respectively. Overall accuracy, sensitivity, specificity, PPV, and NPV for 2-dimensional (2D) quantitative coronary angiography (QCA) were 63.3, 42.5, 70.9, 34.7, and 77.2%, respectively. The average processing time of AccuFFRangio was 4.30 ± 1.87 min.Conclusions: AccuFFRangio computed from coronary ICA images can be an accurate and time-efficient computational tool for detecting lesion-specific ischemia of coronary artery stenosis.

Prognostic Value of Computed Tomographic Coronary Angiography for Long-Term Major Adverse Cardiac Events after Liver Transplantation.

Computed tomographic coronary angiography (CTCA) has prognostic value for early major adverse cardiac events (MACEs) after liver transplantation. However, the association between CTCA and long-term MACEs in liver transplant (LT) recipients remains unknown. We evaluated the association between CTCA and long-term MACEs within 5 years after living donor liver transplantation (LDLT). A total of 628 LDLT recipients who underwent CTCA were analyzed between 2010 and 2012. MACEs were investigated within 5 years after LDLT. The factors associated with long-term MACEs in transplant recipients were evaluated. Only 48 (7.6%) patients developed MACEs. In the Fine and Gray competing risk regression, a coronary artery calcium score (CACS) of >400 combined with obstructive coronary artery disease (CAD) (subdistribution hazard ratio: 5.01, 95% confidence interval: 2.37–10.58, p < 0.001), age (1.05, 1.01–1.10, p = 0.018), diabetes mellitus (2.43, 1.37–4.29, p = 0.002), dyslipidemia (2.45, 1.23–4.70, p = 0.023), and creatinine (1.19, 1.08–1.30, p < 0.001) were independently associated with long-term MACEs. CACS (>400) combined with obstructive CAD may be associated with MACEs within 5 years after LDLT, suggesting the importance of preoperative noninvasive CTCA in LT recipients. The evaluation of coronary artery stenosis on CTCA combined with CACS may have a prognostic value for long-term MACEs in LT recipients.

Diagnostic performance of quantitative flow ratio in prospectively enrolled patients: An individual patient-data meta-analysis.

We aimed to provide robust performance estimates for quantitative flow ratio (QFR) in assessment of intermediary coronary lesions. Angiography-based functional lesion assessment by QFR may appear as a cost saving and safe approach to expand the use of physiology-guided percutaneous coronary interventions. QFR was proven feasible and showed good diagnostic performance in mid-sized off-line and on-line studies with fractional flow reserve (FFR) as reference standard. We performed a collaborative individual patient-data meta-analysis of all available prospective studies with paired assessment of QFR and FFR using the CE-marked QFR application. The main outcome was agreement of QFR and FFR using a two-step analysis strategy with a multilevel mixed model accounting for study and center level variation. Of 16 studies identified, four studies had prospective enrollment and provided patient level data reaching a total of 819 patients and 969 vessels with paired FFR and QFR: FAVOR Pilot (n = 73); WIFI II (n = 170); FAVOR II China (n = 304) and FAVOR II Europe-Japan (n = 272). We found an overall agreement (mean difference 0.009 ± 0.068, I2 = 39.6) of QFR with FFR. The diagnostic performance was sensitivity 84% (95%CI: 77-90, I2 = 70.1), specificity 88% (95%CI: 84-91, I2 = 60.1); positive predictive value 80% (95%CI: 76-85, I2 = 33.4), and negative predictive value 95% (95%CI: 93-96, I2 = 75.9). Diagnostic performance of QFR was good with FFR as reference in this meta-analysis of high quality studies. QFR could provide an easy, safe, and cost-effective solution for functional evaluation of coronary artery stenosis.

Instantaneous wave-free ratio (iFR®) to determine hemodynamically significant coronary stenosis: A comprehensive review.

Coronary angiography is considered to be the gold standard in the morphological evaluation of coronary artery stenosis. The morphological assessment of the severity of a coronary lesion is very subjective. Thus, the invasive fractional flow reserve (FFR) measurement represents the current standard for estimation of the hemodynamic significance of coronary artery stenosis. The FFR-guided revascularization strategy was initially classified as a Class-IA-recommendation in the 2014 European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines on myocardial revascularization. Both the Deferral vs Performance of Percutaneous Coronary Intervention of Functionally Non-Significant Coronary Stenosis and Flow Reserve vs Angiography for Multivessel Evaluation studies showed no treatment advantage for hemodynamically insignificant stenoses. With the help of FFR (and targeted interventions), clinical results could be improved; however, the use in clinical practice is still limited due to the need of adenosine administration and a significant prolongation of the length of the procedure. Instantaneous wave-free ratio (iFR®) is a new innovative approach for the determination of the hemodynamic significance of coronary stenosis, which can be obtained at rest without the use of vasodilators. Regarding the periprocedural complications as well as prognosis, iFR® showed non-inferiority to FFR in the SWEDEHEART and DEFINE-FLAIR trials. Furthermore, iFR®, enhanced by iFR®-pullback, provides the possibility to display the iFR®-change over the course of the vessel to create a hemodynamic map.

Fractional Flow Reserve Versus Angiographically-Guided Coronary Artery Bypass Grafting

BackgroundThe value of fractional flow reserve (FFR) evaluation of coronary artery stenosis in coronary artery bypass grafting (CABG) is uncertain, and stenosis assessments usually rely on visual estimates of lesion severity. ObjectivesThis randomized clinical trial evaluated graft patency and clinical outcome after FFR-guided CABG versus angiography-guided CABG. MethodsA total of 100 patients referred for CABG were randomly assigned to FFR-guided or angiography-guided CABG. Based on the coronary angiogram, a heart team made a graft plan for all patients, and FFR evaluations were performed. In FFR-guided CABG, coronary lesions with FFR >0.80 were deferred, and a new graft plan was designed accordingly, whereas the surgeon was blinded to the FFR values in patients who underwent angiography-guided CABG. The primary endpoint was graft failure in the percentage of all grafts after 6 months. ResultsAngiographic follow-up at 6 months was available for 72 patients (39 vs. 33 in the FFR-guided and angiography-guided groups, respectively). Graft failures of all grafts were similar in both groups (16% vs. 12%; p = 0.97). Rates of death, myocardial infarction, and stroke were also similar in the study groups, and no difference was seen in revascularization before angiographic follow-up. After 6 months, deferred lesions (n = 24) showed a significant reduction in mean FFR from index to follow-up (0.89 ± 0.05 vs. 0.81 ± 0.11; p = 0.002). Index FFR did not influence graft patency. ConclusionsFFR-guided CABG had similar graft failure rates and clinical outcomes as angiography-guided CABG. However, FFR was reduced significantly after 6 months in deferred lesions. (Fractional Flow Reserve Versus Angiography Randomization for Graft Optimization [FARGO]; NCT02477371)

Evaluation of Coronary Artery Stenosis by Quantitative Flow Ratio During Invasive Coronary Angiography: The WIFI II Study (Wire-Free Functional Imaging II).

Quantitative flow ratio (QFR) is a novel diagnostic modality for functional testing of coronary artery stenosis without the use of pressure wires and induction of hyperemia. QFR is based on computation of standard invasive coronary angiographic imaging. The purpose of WIFI II (Wire-Free Functional Imaging II) was to evaluate the feasibility and diagnostic performance of QFR in unselected consecutive patients. WIFI II was a predefined substudy to the Dan-NICAD study (Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease), referring 362 consecutive patients with suspected coronary artery disease on coronary computed tomographic angiography for diagnostic invasive coronary angiography. Fractional flow reserve (FFR) was measured in all segments with 30% to 90% diameter stenosis. Blinded observers calculated QFR (Medis Medical Imaging bv, The Netherlands) for comparison with FFR. FFR was measured in 292 lesions from 191 patients. Ten (5%) and 9 patients (5%) were excluded because of FFR and angiographic core laboratory criteria, respectively. QFR was successfully computed in 240 out of 255 lesions (94%) with a mean diameter stenosis of 50±12%. Mean difference between FFR and QFR was 0.01±0.08. QFR correctly classified 83% of the lesions using FFR with cutoff at 0.80 as reference standard. The area under the receiver operating characteristic curve was 0.86 (95% confidence interval, 0.81-0.91) with a sensitivity, specificity, negative predictive value, and positive predictive value of 77%, 86%, 75%, and 87%, respectively. A QFR-FFR hybrid approach based on the present results enables wire-free and adenosine-free procedures in 68% of cases. Functional lesion evaluation by QFR assessment showed good agreement and diagnostic accuracy compared with FFR. Studies comparing clinical outcome after QFR- and FFR-based diagnostic strategies are required. URL: https://www.clinicaltrials.gov. Unique identifier: NCT02264717.

Improved diagnostic performance of transluminal attenuation gradient in combination with morphological evaluation of coronary artery stenosis using 320-row computed tomography.

To assess the utility of transluminal attenuation gradient (TAG) in combination with coronary computed tomography angiography (CTA) for detecting obstructive coronary artery stenosis. We retrospectively evaluated coronary CTA data in 35 consecutive patients who underwent invasive coronary angiography (ICA). We compared the diagnostic performance of TAG with that of quantitative coronary angiography, which we used as the reference standard. For the combination of TAG and coronary CTA, we designed a logical conjunction model (CCTA&&TAG) as well as a logical disjunction model (CCTA||TAG), and evaluated their diagnostic accuracies. Among 130 vessels of 35 patients, 30 lesions (23%) showed significant stenosis on ICA. TAG predicted significant coronary artery stenosis with a sensitivity of 75%, specificity of 63%, positive predictive value of 40%, negative predictive value of 89%, and accuracy of 66%, and had a cutoff value of -15.4HU/10mm. The respective values for CCTA&&TAG were 73, 98, 88, 90, and 90%; those for CCTA||TAG were 94, 61, 56, 94, and 72%. CCTA&&TAG improved the diagnostic accuracy significantly more than CCTA||TAG. TAG in conjunction with coronary CTA improves the diagnostic accuracy of coronary CTA.

Recent progress in functional evaluation of coronary artery stenosis by CT

Recent progress in functional evaluation of coronary artery stenosis by CT

Computational fluid dynamics with application of different theoretical flow models for the evaluation of coronary artery stenosis on CT angiography: comparison with invasive fractional flow reserve

The purpose of this study is to use the coronary computed tomography angiography (CCTA) to simulate the coronary blood flow with different theoretical flow models by using not only the computation fluid dynamics (CFD) method, but also additional patient boundary conditions obtained with echocardiography, and evaluate the feasibility of simulated fractional flow reserve (FFRCTS), compared with the invasive CTA-based FFR. The laminar and three turbulence models (k-ε(k-epsilon), k-ω(k-omega), SST (Menter’s shear stress transport)) were implemented to predict coronary blood flow. The study investigates an ideal stenosis model and six patients, with invasive FFR measurements. Three-dimensional reconstructions of coronary arteries of six subjects were performed from CCTA images of 320-detector scanner. The measured velocity profile of the left ventricular outflow tract from the echocardiography was employed for the inlet velocity in simulation. The pressure waveform of the patient aortic blood flow was used as the pressure profile at the outlet. With simulations, we found that the maximum velocity in the stenotic coronary artery reached about 395 cm s−1, which was about 2.4 times faster than the inlet velocity of 165 cm s−1 for the patient with coronary stenosis diagnosed 50%–75% on CTA. The pressure drop across the stenosis was about 28 mmHg. Meanwhile, the value of FFRCTS using the laminar flow pattern was 0.788 closely to its invasive FFR of 0.79. In conclusion, this study demonstrated that the CFD method has moderate more blood flow information to assess the hemodynamic significance of the coronary blood flow and calculate the non-invasive FFRCTS values, which were very close to those measured with invasive FFR.

The value of noninvasive computed tomography derived fractional flow reserve in our current approach to the evaluation of coronary artery stenosis.

Contemporary diagnosis and management of stable chest pain symptoms possibly due to coronary ischemia is a frequent clinical challenge that involves a variety of test options, based upon either coronary angiographic (anatomic) or functional imaging. This review will discuss the evolution of coronary computed tomography derived fractional flow reserve (FFRCT) from basic science to a currently clinically approved diagnostic test. In recent years, FFR measured invasively in the coronary catheterization lab has demonstrated clinical outcome benefit for coronary revascularization decisions. Both coronary angiographic (anatomic) and functional myocardial imaging have been limited by an inability to reliably estimate physiologic significance determined by FFR. However, advances in computational fluid dynamics have led to interest in FFR estimated by coronary angiograms obtained noninvasively through coronary CT angiography. The current use of FFRCT has been mostly limited to research applications due to lack of availability and cost, as well as limited outcomes and cost-effectiveness data. Nevertheless, interest remains in the potential role of FFRCT for coronary revascularization treatment decisions, and thus, ongoing and future studies will continue to investigate this technology.

Comparison of rubidium-82 myocardial blood flow quantification with coronary calcium score for evaluation of coronary artery stenosis

PET myocardial perfusion imaging (MPI) is the standard technique for assessing myocardial function, but provides limited information on the anatomy of cardiac structures whereas the coronary artery calcium (CAC) score provides information on calcified plaque burden and the anatomical structure of the coronary arteries. The aim of this study was to determine the relationship between quantitative myocardial blood flow (MBF), CAC, and coronary artery disease (CAD). This work also aims to determine whether MBF quantification and/or CAC add value to relative MPI, and aid in the reclassification of patients with CAD. This way, a 'gatekeeper' study could be identified to predict coronary artery stenosis and improve our clinical service. Rubidium-82 PET/CT MPI, calcium score, and computed tomographic coronary angiography imaging were performed in 128 patients with known or suspected CAD. The presence of ischemia was assessed from qualitative reporting of rubidium-82 MPI, and using the same data, quantitative values of MBF and coronary flow reserve (CFR) were derived. Calcium score images were quantitatively analyzed and categorized into three groups defined by CAC values of 0, 1-400, and >400. Significant stenosis was classified as stenosis of 50% or more on computed tomographic angiography. A total of 120 patients were included in the final analysis (77 men, 43 women). Our results showed an inverse correlation between stress MBF, CFR, and the percentage stenosis as well as an inverse correlation compared with CAC. A direct correlation between CAC and the percentage stenosis was observed, indicating that an increase in coronary calcification in individual coronary arteries is related to the severity of the coronary stenosis. These results proved that the addition of stress MBF to relative MPI (32%) resulted in a significantly higher sensitivity (48%, P=0.002), which increased significantly more with the addition of CFR (58%, P≤0.001). The further addition of CAC resulted in a significantly higher sensitivity (80%, P=0.001), with an even higher sensitivity with the addition of both CFR and CAC (95%, P≤0.001) to relative MPI. The addition of quantitative MBF conferred a substantial added diagnostic value to relative MPI for the diagnosis of CAD by highlighting compromised flow with the addition of CAC, increasing this added value even more. We recommend that this approach should be used to predict the presence of coronary artery stenosis at its earliest stage and guide physicians when making decisions on the management pathway of CAD without exposing patients to a high radiation dose during cardiac angiography.

Role of Cardiac Computed Tomography in the Evaluation of Coronary Artery Stenosis in Patients With Ascending Aorta Aneurysm Detected at Transthoracic Echocardiography.

The aim of our study was to evaluate the diagnostic performance of cardiac computed tomography (CCT) in the evaluation of coronary artery stenosis in patients with ascending aorta aneurysm detected at transthoracic echocardiography. We conducted a retrospective analysis of patients with an aneurysm 45 mm or greater at transthoracic echocardiography who underwent CCT from 2012 to 2014 in our hospital. We calculated the sensitivity, specificity, and positive and negative predictive values of CCT for the assessment of coronary artery stenosis (<50% or ≥50% stenosis) in patients who underwent conventional coronary angiography. We included 104 patients (73 men, aged 64 [SD, 10.8] years) in our study. Obstructive coronary artery disease was found in 22.1% of patients. Sensitivity, specificity, and positive and negative predictive values of CCT for detecting significant stenoses were 100%, 98%, and 82% and 100% on a segment-by-segment analysis and 100%, 83%, and 65% and 100% on a per-patient analysis, respectively. Cardiac computed tomography provides a comprehensive evaluation of ascending aorta aneurysms and coronary artery tree.

Radiation dose and diagnostic accuracy of high-pitch dual-source coronary angiography in the evaluation of coronary artery stenoses.

"Flash Spiral" imaging is a new prospective ECG-triggered spiral scan mode that uses a very high-pitch for coronary computed tomography angiography (CTA). This enables complete image acquisition within one cardiac cycle with a very low radiation exposure. The aim of this study was to investigate the diagnostic accuracy, image quality, and effective radiation dose of prospectively ECG-triggered high-pitch spiral method (Flash spiral mode) of coronary CTA using dual-source technology for the evaluation of coronary artery stenoses. The study included 186 consecutive patients (115men, 71women; mean age: 53.37years) who underwent coronary CTA. Coronary CTA was performed with a 128×2-slice dual-source CT (Somatom Definition Flash, Siemens, Germany) using a prospectively ECG-triggered high-pitch spiral mode. Patients were divided into three groups according to heart rate (≤65bpm, 66-75bpm, ≥76bpm) and body mass index (BMI) (20-24kg/m(2), 25-29kg/m(2), 30-34kg/m(2)) values. The correlation between heart rates, image quality and BMI values are investigated. A four-point scale (1=excellent, 4=poor/non-diagnostic) was used to rank the comparative image quality. Effective radiation doses were calculated. Also the correlation between radiation dose, sex and BMI values were investigated. In addition, diagnostic accuracy of CTA for detection of significant (≥50%) coronary artery stenoses was compared with invasive coronary angiography findings of 612vessel segments in 38patients. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy rate were calculated. A total of 2976coronary artery segments were present. Of all coronary artery segments, 2381 (80%) had an image quality score of 1, and 1.5% segments were rated as "poor/non-diagnostic". When the correlation between heart rate and image quality is investigated, there was a significant difference between ≤65bpm and ≥76bpm groups. However, there was no significant difference between ≤65bpm and 66-75bpm groups. The mean effective dose was found as 1.3mSv (min: 0.5, max: 2.4mSv). The correlation between effective radiation dose and BMI was moderate. However, the correlation between gender and radiation dose was significant. Sensitivity, specificity, negative predictive value and accuracy of coronary CTA on a per-vessel segment were 90.1%, 97.4%, 98.6%, and 96.5%, respectively. Prospectively ECG-triggered high-pitch spiral mode coronary CTA provides high image quality and diagnostic accuracy, with very low radiation dose for evaluation and exclusion of coronary artery stenoses.

Myocardial perfusion analysis in cardiac computed tomography angiographic images at rest.

Cardiac computed tomography angiography (CTA) is a non-invasive method for anatomic evaluation of coronary artery stenoses. However, CTA is prone to artifacts that reduce the diagnostic accuracy to identify stenoses. Further, CTA does not allow for determination of the physiologic significance of the visualized stenoses. In this paper, we propose a new system to determine the physiologic manifestation of coronary stenoses by assessment of myocardial perfusion from typically acquired CTA images at rest. As a first step, we develop an automated segmentation method to delineate the left ventricle. Both endocardium and epicardium are compactly modeled with subdivision surfaces and coupled by explicit thickness representation. After initialization with five anatomical landmarks, the model is adapted to a target image by deformation increments including control vertex displacements and thickness variations guided by trained AdaBoost classifiers, and regularized by a prior of deformation increments from principal component analysis (PCA). The evaluation using a 5-fold cross-validation demonstrates the overall segmentation error to be 1.00 ± 0.39 mm for endocardium and 1.06 ± 0.43 mm for epicardium, with a boundary contour alignment error of 2.79 ± 0.52. Based on our LV model, two types of myocardial perfusion analyzes have been performed. One is a perfusion network analysis, which explores the correlation (as network edges) pattern of perfusion between all pairs of myocardial segments (as network nodes) defined in AHA 17-segment model. We find perfusion network display different patterns in the normal and disease groups, as divided by whether significant coronary stenosis is present in quantitative coronary angiography (QCA). The other analysis is a clinical validation assessment of the ability of the developed algorithm to predict whether a patient has significant coronary stenosis when referenced to an invasive QCA ground truth standard. By training three machine learning techniques using three features of normalized perfusion intensity, transmural perfusion ratio, and myocardial wall thickness, we demonstrate AdaBoost to be slightly better than Naive Bayes and Random Forest by the area under receiver operating characteristics (ROC) curve. For the AdaBoost algorithm, an optimal cut-point reveals an accuracy of 0.70, with sensitivity and specificity of 0.79 and 0.64, respectively. Our study shows perfusion analysis from CTA images acquired at rest is useful for providing physiologic information in diagnosis of obstructive coronary artery stenoses.

Noninvasive physiologic assessment of coronary stenoses using cardiac CT.

Coronary CT angiography (CCTA) has become an important noninvasive imaging modality in the diagnosis of coronary artery disease (CAD). CCTA enables accurate evaluation of coronary artery stenosis. However, CCTA provides limited information on the physiological significance of stenotic lesions. A noninvasive “one-stop-shop” diagnostic test that can provide both anatomical significance and functional significance of stenotic lesions would be beneficial in the diagnosis and management of CAD. Recently, with the introduction of novel techniques, such as myocardial CT perfusion, CT-derived fractional flow reserve (FFRCT), and transluminal attenuation gradient (TAG), CCTA has emerged as a noninvasive method for the assessment of both anatomy of coronary lesions and its physiological consequences during a single study. This review provides an overview of the current status of new CT techniques for the physiologic assessments of CAD.