Takeshi Nojo

Adaptive Iterative Dose Reduction in coronary CT angiography using 320-row CT: Assessment of radiation dose reduction and image quality

BACKGROUNDnSeveral methods have been developed to reduce the radiation dose in coronary computed tomography angiography (CTA).nnnOBJECTIVEnThe objective of our study was to evaluate the effects of Adaptive Iterative Dose Reduction (AIDR) on objective and subjective image quality as well as the radiation dose, compared with conventional filtered back projection (FBP), in coronary CTA.nnnMETHODSnWe retrospectively reviewed 100 consecutive patients who underwent coronary CTA. In the first 50 patients, a higher tube current was used, and images were reconstructed with FBP. In the last 50 patients, a lower tube current was used, and images were reconstructed with AIDR. Subjective and objective image quality (noise, signal-to-noise ratio, contrast-to-noise ratio) were assessed.nnnRESULTSnThe median radiation dose of the AIDR group was 22% lower than that of the FBP group (4.2 vs 5.4 mSv; P = 0.0001). No significant difference was found in subjective image quality, noise, signal-to-noise ratio, or contrast-to-noise ratio between the 2 groups.nnnCONCLUSIONnAIDR reduced the tube current which resulted in reduction of radiation dose in coronary CTA while maintaining subjective and objective image quality compared with coronary CTA reconstructed with FBP.

Difference of coronary artery disease severity, extent and plaque characteristics between patients with hypertension, diabetes mellitus or dyslipidemia

Abstract The purpose of this study was to investigate the difference of coronary artery disease (CAD) severity and extent as well as plaque characteristics between patients with either one of hypertension (HT), diabetes mellitus (DM) or dyslipidemia (DL). We retrospectively reviewed the records of 1,161 patients (HT 442, DM 77, DL 248, no disease 394) who underwent coronary computed tomography angiography. Stenosis severity was classified as normal, non-obstructive (1–49xa0% stenosis), moderate (50–69xa0% stenosis) or severe (≥70xa0% stenosis). Segment involvement score (SIS) and segment severity score (SSS) was calculated. We defined patients at risk as patients with obstructive CAD or non-obstructive CAD with extensive disease (SIS ≥xa05). Plaque characteristics were evaluated including positive remodeling, low attenuation and spotty calcification. Obstructive CAD was most frequent in DM patients, followed by HT and DL patients (34, 19 and 15xa0%, respectively, pxa0<xa00.0001). DM patients had more extensive disease than HT and DL patients (SIS 3.1 vs 2.1 vs 1.4, SSS 4.0 vs 2.7 vs 2.0). DM patients were more at risk than HT and DL patients (pxa0<xa00.05). The prevalence of positive remodeling, low attenuation and spotty calcium were all highest in DM patients (pxa0<xa00.005, vs HT and DL), while low attenuation was more frequent in DL than HT patients (pxa0<xa00.005). The median calcium score of HT and DM patients were higher than DL patients (pxa0<xa00.01 and pxa0<xa00.005, respectively), while no significant difference was observed between HT and DM patients. In conclusion,xa0DM patients possessed more high risk plaque and obstructive as well as extensive CAD compared with HT and DL patients. Coronary calcification was similarly high in HT and DM patients. Low attenuation plaque was more frequent in DL than HT patients.

Shorter delay time reduces interpatient variability in coronary enhancement in coronary CT angiography using the bolus tracking method with 320-row CT

The purpose was to investigate the influence of shorter delay time on the interpatient variability in coronary enhancement and appropriateness of scan timing in coronary CT angiography (CTA) using bolus tracking method with 320-row CT. The bolus tracking scan was performed at the level of the bifurcation of the trachea for first 50 patients (group 1) and at the center level of the diagnostic scan for the last 50 patients (group 2). The CT number of the proximal coronary arteries was measured in the right coronary artery (RCA) and the left main trunk (LMT). The CT numbers of the right ventricle, left ventricle, ascending aorta, and descending aorta were also measured to consider the appropriateness of the scan timing. The delay time was longer in group 1 than in group 2 (7.0 vs. 2.6xa0s; pxa0<xa00.0001). The CT number within the RCA was 390xa0±xa075xa0HU for group 1 and 419xa0±xa042xa0HU for group 2. The CT number within the LMT was 396xa0±xa072xa0HU for group 1 and 420xa0±xa040xa0HU for group 2. The difference of average (pxa0=xa00.02 and 0.04) and standard deviation (pxa0=xa00.03 and 0.02) was statistically significant. The scan timing was early or late in 15 patients for group 1, but only 2 patients for group 2 (pxa0=xa00.0002). Shortening the delay time could reduce the interpatient variability in coronary enhancement with appropriate scan timing in coronary CTA.

Improving the diagnostic performance of the real world coronary computed tomography angiography including uninterpretable segments.

OBJECTIVESnThe purpose was to investigate the diagnostic performance of coronary computed tomography angiography (CTA) when non-calcified uninterpretable segments were determined as either obstructive or patent. We also investigated the factors that could improve the diagnosis of CTA.nnnMETHODSnA total of 268 patients without known coronary artery disease who were clinically indicated for coronary angiogram (CAG) within 50days of coronary CTA were retrospectively included. The diagnostic performance of CTA was assessed with CAG as a reference, whereas stenosis of ≥50% was considered obstructive. We compared the results when non-calcified uninterpretable segments were determined as obstructive or patent. Coronary risk factors as well as contrast medium arrival time adjusted by heart rate (CATHR) were investigated for improvement of CTA diagnosis.nnnRESULTSnArea under the receiver operating characteristic curve (AUC) improved when uninterpretable segments were determined as patent rather than obstructive (0.79 vs 0.73, p=0.02). Multivariate analysis showed that CATHR was a predictor of CAG stenosis (odds ratio 1.13, p=0.046) while other risk factors were not. Adding CATHR further improved the AUC to 0.82 (p=0.003). The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of CTA stenosis (uninterpretable segments as obstructive) were 72%, 99%, 32%, 68% and 95%. The values were 78%, 89%, 61%, 77% and 80% when CATHR was added and uninterpretable segments determined as patent.nnnCONCLUSIONSnThe diagnostic performance of coronary CTA improved when non-calcified uninterpretable segments were determined as patent rather than obstructive. Adding CATHR could further improve the specificity.

Clinical utility of landiolol for use in coronary CT angiography

License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Research Reports in Clinical Cardiology 2015:6 145–152 Research Reports in Clinical Cardiology Dovepress

The association of hemoglobin A1c and high risk plaque and plaque extent assessed by coronary computed tomography angiography

The objective of this study was to investigate the relationship of Hemoglobin A1c (HbA1c) and plaque characteristics including high risk plaque and plaque extent. We retrospectively examined 1079 consecutive coronary computed tomographyxa0(CT) angiography scans and the HbA1c results. We divided the patients into four groups by the HbA1c status: non-diabetic, ≤6.0; borderline, 6.1–6.4; diabetic low, 6.5–7.1; diabetic high, >7.1. We determined segment involvement score >4 as extensive disease. High risk plaque was defined as two feature positive (FP) plaque which consists of positive remodeling (remodeling index >1.1) and low attenuation (<30 HU). Univariate and multivariate analysis including conventional cardiovascular risk factors, symptoms and medication was performed. Univariate analysis showed that diabetic patients as well as borderline patients were significantly related with 2FP plaque and extensive disease. Although the relationship of borderline patients and 2FP plaque was marginal in multivariate analysis [odds ratio (OR) 1.53, 95xa0% confidence interval (CI) 0.95–2.40, pxa0=xa00.07], the elevation of HbA1c was strongly associated with 2FP plaque (diabetic low, OR 2.19, 95xa0% CI 1.37–3.45, pxa0<xa00.005; diabetic high, OR 4.14, 95xa0% CI 2.57–6.67, pxa0<xa00.0005). The association of HbA1c elevation and extensive disease was quite similar between borderline and diabetic patients (borderline, OR 1.96, 95xa0% CI 1.29–2.95, pxa0<xa00.005; diabetic low, OR 1.94, 95xa0% CI 1.25–3.01, pxa0<xa00.005; diabetic high, OR 2.19, 95xa0% CI 1.39–3.43, pxa0<xa00.005). Patients with elevated HbA1c of >6.0 are potentially at risk for future cardiovascular events due to increased high risk plaque and extensive disease, even below the diabetic level of 6.5. Coronary CT could be used for risk stratification of these patients.

High prevalence of coronary artery events and non-coronary events in patients with coronary artery aneurysm in the observational group

Background Coronary artery aneurysm (CAA) is occasionally detected on a small percentage of coronary angiography or multi-detector computed tomography (MDCT). CAA itself is considered benign entity despite the potential risks of rupture, thromboembolism, and compression of surrounding structures. However, the optimal management including other vascular comorbidity has yet to be fully clarified. Objective The aim of this study was to evaluate cardiovascular events in the patients with CAA in the observational group. Methods Between January 2010 and August 2015, 48 CAAs were identified in 37 patients out of consecutive 10,010 patients (0.37%) by MDCT. Twenty-eight patients treated conservatively were included in this study. Their major adverse cardiovascular events (MACE) were evaluated retrospectively: death, non-fatal myocardial infarction (MI), revascularizations; coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI), and other vascular events. Results The average age was 62.0 ± 15.5 year sold, and median follow-up period was 49.6 months (IQR 23.6 to 78.1). Mean CAA diameter was 7.5 ± 2.8 mm. Twenty-two MACE occurred in 15 patients (53.6%): 1 sudden death, 4 MI, 1 CABG for CAA, 3 PCI for CAA, 7 PCI for non-CAA lesions, and 6 other vascular treatments for aorta and cerebral and peripheral artery. Follow-up MDCT was performed for 22 CAAs in 16 patients. In 9 CAAs of them, the maximal diameter increased significantly (Δ diameter: 1.5 ± 1.1 mm). Conclusions Presence of CAA may be associated with adverse vascular events including non-coronary diseases. This study could suggest the management for CAA should include the evaluation of not only CAA itself but also other vascular diseases.

Relationship of hepatic steatosis severity and coronary artery disease characteristics assessed by coronary CT angiography

The objective of this study was to investigate the relationship between the severity of hepatic steatosis and coronary artery disease characteristics assessed by coronary computed tomography (CT) angiography. This retrospective analysis consisted of 2028 patients. Hepatic steatosis was evaluated by liver attenuation on unenhanced CT and the patients were divided into four groups (≥60xa0HU, 54–59xa0HU, 43–53xa0HU, ≤42xa0HU). Coronary calcification was calculated using the Agatston method. Obstructive disease was defined as ≥50xa0% stenosis assessed by CT. A high-risk plaque was defined by a remodeling index >1.1 and low attenuation (<30xa0HU). Patients with a segment involvement score >4 were determined to have extensive disease. Logistic regression analysis was performed to study multivariate associations. Severity of hepatic steatosis was associated with coronary calcification (pxa0=xa00.02), obstructive disease (pxa0<xa00.0001), presence of a high-risk plaque (pxa0=xa00.0001) and extensive disease (pxa0=xa00.001) in the univariate analysis. However, the relationships were attenuated in the multivariate analysis with the exception of obstructive disease (pxa0=xa00.04). Liver attenuation of <54xa0HU was significantly associated with obstructive coronary artery disease independent of conventional risk factors such as age, sex, diabetes mellitus, hypertension, dyslipidemia and smoking (hepatic attenuation 43–53xa0HU, odds ratio 1.52, 95xa0% confidence interval 1.11–2.10, pxa0=xa00.01; ≤42xa0HU, odds ratio 1.65, 95xa0% confidence interval 1.10–2.45, pxa0=xa00.02). Although conventional risk factors were stronger predictors of coronary calcification and plaque formation, the severity of hepatic steatosis remained an independent risk factor for obstructive coronary artery disease. Coronary CT angiography may play a potential role in risk stratification for patients with hepatic steatosis.

Prediction of the attenuation of the ascending aorta using bolus-tracking parameters and heart rate in coronary computed tomography angiography

OBJECTIVEnThe purpose of this study was to evaluate the correlation between bolus-tracking parameters and heart rate (HR) with attenuation of the ascending aorta and create a linear regression model for predicting coronary attenuation in coronary computed tomography angiography (CCTA).nnnMETHODSnA total of 50 patients (31 men, 19 women; mean age, 67.2±10.8 y) underwent CCTA using a 320-detector CT scanner. A bolus-tracking scan was performed to optimize the scan timing. The average HR under normal breathing for 10s was recorded just before the bolus-tracking scan started. Attenuation values of the pulmonary artery at 7s (PA7) and 10s (PA10) after the beginning of the injection were recorded during the bolus-tracking scan and the ascending aortic attenuation (CEAAo) was measured during the diagnostic scan.nnnRESULTSnA positive correlation was observed between PA7 and CEAAo (r=0.41, P=0.003) and PA10 and CEAAo (r=0.66, P<0.0001), and weak negative correlation was observed between HR and CEAAo (r=-0.46, P=0.15). A multivariable linear regression model for predicting CEAAo was evaluated, and the residual error between the predicted and the measured CEAAo was within approximately ±100 HU.nnnCONCLUSIONSnCoronary attenuation could be predicted using HR and pulmonary artery attenuation during the bolus-tracking method.

Association of Contrast Medium Arrival Time with Conventional Risk Factors and Morise Score in Detecting Obstructive Coronary Artery Disease

Association of Contrast Medium Arrival Time with Conventional Risk Factors and Morise Score in Detecting Obstructive Coronary Artery Disease nObjectives: To determine the association of contrast medium arrival time during coronary CT angiography with the conventional coronary risk factors and Morise score in detecting obstructive CAD. Materials and Methods: A total of 665 patients were retrospectively included in the study. Contrast medium arrival time was recorded as the time from the start of the injection to the threshold of 100 HU at the descending aorta during the bolus tracking scan. The Morise score was calculated for each patient and modified Morise score (MMS) was defined as Morise score*heart rate*arrival time/1000. Anatomically obstructive CAD was determined as ≥50% stenosis by CT angiography. Results: Longer contrast medium arrival time was significantly related with obstructive CAD in multivariate analysis (p = 0.03). MMS improved the area under the curve from 0.59 to 0.63 (p = 0.01) with a net reclassification index of 0.14 compared with the Morise score in discriminating patients with obstructive CAD from those without. The presence of obstructive CAD of the 1st quartile of MMS was significantly lower compared with the remaining quartiles (vs 2nd quartile, p = 0.01; vs 3rd quartile, p = 0.002; vs 4th quartile, p < 0.0001). Conclusion: Longer contrast medium arrival time was related with obstructive CAD independent of conventional cardiovascular risk factors. MMS had an additive value over the Morise model alone to predict obstructive CAD in coronary CT angiography.