Project description:AimsPhoton-counting detector computed tomography (PCD-CT), which allows the exclusion of electronic noise, shows promise for significant dose reduction in coronary CT angiography (CCTA). This study aimed to assess the radiation dose and image quality of CCTA using PCD-CT, combined with high-pitch helical scanning and an ultra-low tube potential of 70 kVp, and investigate the effect of a sharp kernel on image quality and stenosis assessment in such an ultra-low-dose CCTA setting.Methods and resultsForty patients (65% male) with stable heart rates and no prior coronary interventions were included. Data on CT dose index volume (CTDIvol) and dose-length product (DLP) were collected, with effective radiation dose estimated using a conversion factor of 0.014. Images were reconstructed using kernels of Bv64 and Bv40 for image quality and stenosis assessment. The mean CTDIvol, DLP, and effective dose of CCTA were 1.72 ± 0.38 mGy, 29.1 ± 6.8 mGy·cm, and 0.41 ± 0.09 mSv, respectively. Image quality was similar (P = 0.75) between the two kernels, with over 95% of segments achieving a rating of good image quality for both kernels. The per-segment stenosis score distribution between Bv40 and Bv64 reconstruction images showed significant differences for both non-calcified and calcified plaques (P < 0.001 for both).ConclusionPCD-CT technology with high-pitch helical scanning and the tube potential of 70 kVp can provide CCTA with ultra-low radiation exposure (DLP, 29 mGy·cm). The noise reduction capability of PCD-CT allows the use of a sharp kernel even in this low-dose CCTA setting without compromising image quality, potentially improving the evaluation of coronary artery stenosis.
Project description:BackgroundEstablishing the diagnosis of coronary artery disease (CAD) in symptomatic patients allows appropriately allocating preventative measures. Single-photon emission computed tomography (CT)-acquired myocardial perfusion imaging (SPECT-MPI) is frequently used for the evaluation of CAD, but coronary CT angiography (CTA) has emerged as a valid alternative.Methods and resultsWe compared the accuracy of SPECT-MPI and CTA for the diagnosis of CAD in 391 symptomatic patients who were prospectively enrolled in a multicenter study after clinical referral for cardiac catheterization. The area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of CTA and SPECT-MPI for identifying patients with CAD defined as the presence of ≥1 coronary artery with ≥50% lumen stenosis by quantitative coronary angiography. Sensitivity to identify patients with CAD was greater for CTA than SPECT-MPI (0.92 versus 0.62, respectively; P<0.001), resulting in greater overall accuracy (area under the receiver operating characteristic curve, 0.91 [95% confidence interval, 0.88-0.94] versus 0.69 [0.64-0.74]; P<0.001). Results were similar in patients without previous history of CAD (area under the receiver operating characteristic curve, 0.92 [0.89-0.96] versus 0.67 [0.61-0.73]; P<0.001) and also for the secondary end points of ≥70% stenosis and multivessel disease, as well as subgroups, except for patients with a calcium score of ≥400 and those with high-risk anatomy in whom the overall accuracy was similar because CTA's superior sensitivity was offset by lower specificity in these settings. Radiation doses were 3.9 mSv for CTA and 9.8 for SPECT-MPI (P<0.001).ConclusionsCTA is more accurate than SPECT-MPI for the diagnosis of CAD as defined by conventional angiography and may be underused for this purpose in symptomatic patients.Clinical trial registrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT00934037.
Project description:BackgroundThe rest-only single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has low diagnostic performance for obstructive coronary artery disease (CAD). Coronary artery calcium score (CACS) is strongly associated with obstructive CAD. The aim of this study was to investigate the performance of rest-only gated SPECT MPI combined with CACS and cardiovascular risk factors in diagnosing obstructive CAD through machine learning (ML).MethodsWe enrolled 253 suspected CAD patients who underwent the 1-stop rest-only SPECT MPI and computed tomography (CT) scan due to stress test-related contraindications. Myocardial perfusion and wall motion were assessed using quantitative perfusion SPECT + quantitative gated SPECT (QPS + QGS) automated quantification software. The Agatston algorithm was used to calculate CACS. The clinical data of patients, including cardiovascular risk factors, were collected. Based on feature selection and clinical experience, 8 factors were identified as modeling variables. Subsequently, patients were divided randomly into 2 groups: the training (70%) and test (30%) groups. The performance of 8 supervised ML algorithms was evaluated in the training and test groups.ResultsObstructive CAD was diagnosed by coronary angiography in 94 (37.2%, 94/253) patients. In the training group, the area under the receiver operator characteristic (ROC) curve (AUC) of the random forest was the highest, and the AUCs of Logistic, extreme gradient boosting (XGBoost), support vector machine (SVM), and adaptive boosting (AdaBoost) were all above 0.9. In the test group, the AUC of recursive partitioning and regression trees (Rpart) was the highest (0.911). Rpart and Naïve Bayes had the highest accuracy (0.840). Rpart had a sensitivity and specificity of 0.851 and 0.821, respectively; Naïve Bayes had a sensitivity and specificity of 0.809 and 0.893, respectively. Next was Logistic, with an accuracy of 0.827, a sensitivity of 0.872, and a specificity of 0.750. The random forest and XGBoost algorithms also had high accuracy, which was 0.813 for each algorithm.ConclusionsRest-only SPECT MPI combined with CACS and cardiovascular risk factors using an ML algorithm to detect obstructive CAD is feasible. Among the algorithms validated in the test group, Rpart, Naïve Bayes, XGBoost, Logistic, and random forest are all highly accurate for diagnosing obstructive CAD. The application of ML in resting MPI and CACS may be used for screening obstructive CAD.
Project description:Coronary artery calcification score (CACS) is well validated prognostic tool in coronary artery disease (CAD). The data on the prevalence of myocardial ischemia on myocardial perfusion single photon emission computed tomography (MPS) in symptomatic patients with zero CACS and low to intermediate risk probability is lacking and controversial. The aim of our study was to evaluate the capability of zero CACS to exclude myocardial ischemia on MPS.A total of 157 patients ((mean age 53 ± 10 years), 88 (56%) female patients, 69 (44%) male patients) who were suspected to have CAD and having low to intermediate pretest likelihood for CAD underwent CACS on dedicated computed tomography (CT) scanners. CACS was reported as zero in all patients, subsequently all patients underwent MPS. Patients with abnormal MPS underwent additional imaging with coronary computed tomography angiography (CCTA).All patients had zero CACS, of which 122 (78%) had normal MPS, and 35 (22%) had abnormal MPS. Abnormal MPS included fixed defect in 22 (13%), equivocal in 10 (6%), and reversible defect in four (3%) patients. All patients with abnormal MPS had further imaging with CTCA. CTCA was normal in 30 (85%) patients, one patient had coronary artery stenosis more than 50%, one patient had coronary artery stenosis less than 50%, one patient had anomalous origin coronary artery, and two patients had myocardial bridging. Patients with abnormal MPS and normal coronary artery had dilated cardiomyopathy in 14 (40%), asymmetrical septal hypotrophy in one (3%), and mitral valve disease in three (9%).Zero CACS in stable patients with low or intermediate risk indicated very low likelihood of obstructive CAD, less than 1%. Patients with zero CACS and normal MPS most likely will not benefit from further testing; however, patients with abnormal MPS will need further imaging with CCTA. CCTA is helpful in this group of patients for evaluation of coronary artery and cardiac morphology.
Project description:ObjectivesVirtual monoenergetic images (VMIs) from photon-counting CT (PCCT) may change quantitative coronary plaque volumes. We aimed to assess how plaque component volumes change with respect to VMIs.MethodsCoronary CT angiography (CTA) images were acquired using a dual-source PCCT and VMIs were reconstructed between 40 and 180 keV in 10-keV increments. Polychromatic images at 120 kVp (T3D) were used as reference. Quantitative plaque analysis was performed on T3D images and segmentation masks were copied to VMI reconstructions. Calcified plaque (CP; > 350 Hounsfield units, HU), non-calcified plaque (NCP; 30 to 350 HU), and low-attenuation NCP (LAP; - 100 to 30 HU) volumes were calculated using fixed thresholds.ResultsWe analyzed 51 plaques from 51 patients (67% male, mean age 65 ± 12 years). Average attenuation and contrast-to-noise ratio (CNR) decreased significantly with increasing keV levels, with similar values observed between T3D and 70 keV images (299 ± 209 vs. 303 ± 225 HU, p = 0.15 for mean HU; 15.5 ± 3.7 vs. 15.8 ± 3.5, p = 0.32 for CNR). Mean NCP volume was comparable between T3D and 100-180-keV reconstructions. There was a monotonic decrease in mean CP volume, with a significant difference between all VMIs and T3D (p < 0.05). LAP volume increased with increasing keV levels and all VMIs showed a significant difference compared to T3D, except for 50 keV (28.0 ± 30.8 mm3 and 28.6 ± 30.1 mm3, respectively, p = 0.63).ConclusionsEstimated coronary plaque volumes significantly differ between VMIs. Normalization protocols are needed to have comparable results between future studies, especially for LAP volume which is currently defined using a fixed HU threshold.Clinical relevance statementDifferent virtual monoenergetic images from photon-counting CT alter attenuation values and therefore corresponding plaque component volumes. New clinical standards and protocols are required to determine the optimal thresholds to derive plaque volumes from photon-counting CT.Key points• Utilizing different VMI energy levels from photon-counting CT for the analysis of coronary artery plaques leads to substantial changes in attenuation values and corresponding plaque component volumes. • Low-energy images (40-70 keV) improved contrast-to-noise ratio, however also increased image noise. • Normalization protocols are needed to have comparable results between future studies, especially for low-attenuation plaque volume which is currently defined using a fixed HU threshold.
Project description:Electrocardiography and high-sensitivity cardiac troponin testing are routinely applied as the initial step for clinical evaluation of patients with suspected non-ST-segment elevation myocardial infarction. Once diagnosed, patients with non-ST-segment elevation myocardial infarction are commenced on antithrombotic and secondary preventative therapies before undergoing invasive coronary angiography to determine the strategy of coronary revascularisation. However, this clinical pathway is imperfect and can lead to challenges in the diagnosis, management, and clinical outcomes of these patients. Computed tomography coronary angiography (CTCA) has increasingly been utilised in the setting of patients with suspected non-ST-segment elevation myocardial infarction, where it has an important role in avoiding unnecessary invasive coronary angiography and reducing downstream non-invasive functional testing for myocardial ischaemia. CTCA is an excellent gatekeeper for the cardiac catheterisation laboratory. In addition, CTCA provides complementary information for patients with myocardial infarction in the absence of obstructive coronary artery disease and highlights alternative or incidental diagnoses for those with cardiac troponin elevation. However, the routine application of CTCA has yet to demonstrate an impact on subsequent major adverse cardiovascular events. There are several ongoing studies evaluating CTCA and its associated technologies that will define and potentially expand its application in patients with suspected or diagnosed non-ST-segment elevation myocardial infarction. We here review the current evidence relating to the clinical application of CTCA in patients with non-ST-segment elevation myocardial infarction and highlight the areas where CTCA is likely to have an increasing important role and impact for our patients.
Project description:PurposeFew studies have reported on predicting prognosis using myocardial perfusion single-photon emission computed tomography (SPECT) during coronary artery disease (CAD) treatment. Therefore, we aimed to assess the clinical implications of myocardial perfusion SPECT during follow-up for CAD treatment.Materials and methodsWe enrolled 1153 patients who had abnormal results at index SPECT and underwent follow-up SPECT at intervals ≥6 months. Major adverse cardiac events (MACE) were compared in overall and 346 patient pairs after propensity-score (PS) matching.ResultsAbnormal SPECT was associated with a significantly higher risk of MACE in comparison with normal SPECT over the median of 6.3 years (32.3% vs. 19.8%; unadjusted p<0.001). After PS matching, abnormal SPECT posed a higher risk of MACE [32.1% vs. 19.1%; adjusted hazard ratio (HR)=1.73; 95% confidence interval (CI)=1.27-2.34; p<0.001] than normal SPECT. After PS matching, the risk of MACE was still higher in patients with abnormal follow-up SPECT in the revascularization group (30.2% vs. 17.9%; adjusted HR=1.73; 95% CI=1.15-2.59; p=0.008). Low ejection fraction [odds ratio (OR)=5.33; 95% CI=3.39-8.37; p<0.001] and medical treatment (OR=2.68; 95% CI=1.93-3.72; p<0.001) were independent clinical predictors of having an abnormal result on follow-up SPECT.ConclusionAbnormal follow-up SPECT appears to be associated with a high risk of MACE during CAD treatment. Follow-up SPECT may play a potential role in identifying patients at high cardiovascular risk.
Project description:Women with myocardial infarction with no obstructive coronary artery disease (MINOCA) are increasingly recognized. Women with MINOCA are at high risk for major adverse cardiovascular events. In this case, we focus on the importance of early identification and management of MINOCA to improve patients' angina and related quality of life. (Level of Difficulty: Beginner.).
Project description:ObjectivesThis study was designed to investigate whether coronary computed tomography angiography assessments of coronary plaque might explain differences in the prognosis of men and women presenting with chest pain.BackgroundImportant sex differences exist in coronary artery disease. Women presenting with chest pain have different risk factors, symptoms, prevalence of coronary artery disease and prognosis compared to men.MethodsWithin a multicenter randomized controlled trial, we explored sex differences in stenosis, adverse plaque characteristics (positive remodeling, low-attenuation plaque, spotty calcification, or napkin ring sign) and quantitative assessment of total, calcified, noncalcified and low-attenuation plaque burden.ResultsOf the 1,769 participants who underwent coronary computed tomography angiography, 772 (43%) were female. Women were more likely to have normal coronary arteries and less likely to have adverse plaque characteristics (p < 0.001 for all). They had lower total, calcified, noncalcified, and low-attenuation plaque burdens (p < 0.001 for all) and were less likely to have a low-attenuation plaque burden >4% (41% vs. 59%; p < 0.001). Over a median follow-up of 4.7 years, myocardial infarction (MI) occurred in 11 women (1.4%) and 30 men (3%). In those who had MI, women had similar total, noncalcified, and low-attenuation plaque burdens as men, but men had higher calcified plaque burden. Low-attenuation plaque burden predicted MI (hazard ratio: 1.60; 95% confidence interval: 1.10 to 2.34; p = 0.015), independent of calcium score, obstructive disease, cardiovascular risk score, and sex.ConclusionsWomen presenting with stable chest pain have less atherosclerotic plaque of all subtypes compared to men and a lower risk of subsequent MI. However, quantitative low-attenuation plaque is as strong a predictor of subsequent MI in women as in men. (Scottish Computed Tomography of the HEART Trial [SCOT-HEART]; NCT01149590).