Non-obstructive low attenuation coronary plaque predicts three-year acute coronary syndrome events in patients with hypertension: Multidetector computed tomographic study

Increased incidence of napkin-ring sign plaques on cervicocerebral computed tomography angiography associated with the risk of acute ischemic stroke occurrence

OBJECTIVES

Carotid atherosclerosis plays an essential role in the occurrence of ischemic stroke. This study aimed to investigate whether a larger burden of napkin-ring sign (NRS) plaques on cervicocerebral computed tomography angiography (CTA) increased the risk of acute ischemic stroke (AIS).

METHODS

This retrospective, single-center, cross-sectional study enrolled patients with NRS plaques identified in the subclavian arteries, brachiocephalic trunk, carotid arterial system, and vertebrobasilar circulation on contrast-enhanced cervicocerebral CTA. Patients were divided into AIS and non-AIS groups based on imaging within 12 h of symptom onset. Univariate and multivariate logistic regression analyses were performed to determine the risk factor of AIS occurrence.

RESULTS

A total of 202 patients (66.72 years ± 8.97, 157 men) were evaluated. Plaques with NRS in each subject of the AIS group (N = 98) were significantly more prevalent than that in the control group (N = 104) (1.96 ± 1.17 vs 1.41 ± 0.62). In the AIS group, there were substantially more NRS plaques on the ipsilateral side than contralateral side (1.55 ± 0.90 vs. 0.41 ± 0.66). NRS located on the ipsilateral side of the AIS showed an area under the receiver curve (AUC) of 0.86 to identify ischemic stroke. NRS plaque amounts were an independent risk factor for AIS occurrence (odds ratio, 1.86) after adjusting for other factors.

CONCLUSIONS

Increased incidence of napkin-ring sign plaques on cervicocerebral CTA was positively associated with AIS occurrence, which could aid in detecting asymptomatic atherosclerotic patients at high risk of AIS in routine screening or emergency settings.

CLINICAL RELEVANCE STATEMENT

Napkin-ring sign plaque provides an important imaging target for estimating acute ischemic stroke risk and identifying high-risk patients in routine screening or emergency settings, so that timely anti-atherosclerotic therapy can be used for prevention.

KEY POINTS

• This cross-sectional study investigated the association between high-risk carotid artery plaques and acute ischemic stroke. • Increased incidence of napkin-ring sign plaques on cervicocerebral computed tomography angiography is positively associated with acute ischemic stroke occurrence. • Napkin-ring signs help identify risky patients prone to acute ischemic stroke to facilitate prevention.

Predicting future left anterior descending artery events from non-culprit lesions: insights from the Lipid-Rich Plaque study

AIMS

The left anterior descending (LAD) artery is the most frequently affected site by coronary artery disease. The prospective Lipid Rich Plaque (LRP) study, which enrolled patients undergoing imaging of non-culprits followed over 2 years, reported the successful identification of coronary segments at risk of future events based on near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) lipid signals. We aimed to characterize the plaque events involving the LAD vs. non-LAD segments.

METHODS AND RESULTS

LRP enrolled 1563 patients from 2014 to 2016. All adjudicated plaque events defined by the composite of cardiac death, cardiac arrest, non-fatal myocardial infarction, acute coronary syndrome, revascularization by coronary bypass or percutaneous coronary intervention, and rehospitalization for angina with >20% stenosis progression and reported as non-culprit lesion-related major adverse cardiac events (NC-MACE) were classified by NIRS-IVUS maxLCBI4 mm (maximum 4-mm Lipid Core Burden Index) ≤400 or >400 and association with high-risk-plaque characteristics, plaque burden ≥70%, and minimum lumen area (MLA) ≤4 mm2. Fifty-seven events were recorded with more lipid-rich plaques in the LAD vs. left circumflex and right coronary artery; 12.5% vs. 10.4% vs. 11.3%, P = 0.097. Unequivocally, a maxLCBI4 mm >400 in the LAD was more predictive of NC-MACE [hazard ratio (HR) 4.32, 95% confidence interval (CI) (1.93-9.69); P = 0.0004] vs. [HR 2.56, 95% CI (1.06-6.17); P = 0.0354] in non-LAD segments. MLA ≤4 mm2 within the maxLCBI4 mm was significantly higher in the LAD (34.1% vs. 25.9% vs. 13.7%, P < 0.001).

CONCLUSION

Non-culprit lipid-rich segments in the LAD were more frequently associated with plaque-level events. LAD NIRS-IVUS screening may help identify patients requiring intensive surveillance and medical treatment.

Effect of semaglutide on coronary atherosclerosis progression in patients with type II diabetes: rationale and design of the semaglutide treatment on coronary progression trial

BACKGROUND

Cardiovascular morbidity and mortality are a major burden in patients with type 2 diabetic mellitus. In a landmark study, semaglutide (an injectable glucagon like peptide-1 receptor agonist) has been shown to significantly reduce cardiovascular events, however, the mechanism of benefit is still unknown. The primary hypothesis of our current study is to assess the effect of semaglutide to reduce progression of noncalcified coronary atherosclerotic plaque volume as measured by serial coronary CTA as compared to placebo in persons with diabetes over 1 year.

METHODS

One hundred forty patients will be enrolled after signing informed consent and followed up for 12 months and with a phone call 30 days after medical discontinuation. All the participants will undergo coronary artery calcium scoring and coronary computed tomography angiography at our center at baseline and 12 months. Eligible participants will be randomly assigned to semaglutide 2 mg/1.5 ml (1.34 mg/ml) prefilled pen for subcutaneous (SC) injection or placebo 1.5 ml, pen-injector for SC injection in a 1:1 fashion as add-on to their standard of care.

RESULTS

As of July 2019, the study was approximately 30% enrolled with an estimated enrollment completion by first quarter of 2020 and end of study by first quarter 2021. Thirty patients were enrolled as of 23 July 2019. Preliminary data of demographics and clinical characteristics were summarized.

CONCLUSION

Our current study will provide important imaging-derived data that may add relevance to the clinically derived outcomes from liraglutide effect and action in diabetes: evaluation of cardiovascular outcome results and semaglutide and cardiovascular outcomes in patients with type 2 diabetic mellitus 6 trials.

Effect of Vascepa (icosapent ethyl) on progression of coronary atherosclerosis in patients with elevated triglycerides (200-499 mg/dL) on statin therapy: Rationale and design of the EVAPORATE study

Despite reducing progression and promoting regression of coronary atherosclerosis, statin therapy does not fully address residual cardiovascular (CV) risk. High‐purity eicosapentaenoic acid (EPA) added to a statin has been shown to reduce CV events and induce regression of coronary atherosclerosis in imaging studies; however, data are from Japanese populations without high triglyceride (TG) levels and baseline EPA serum levels greater than those in North American populations. Icosapent ethyl is a high‐purity prescription EPA ethyl ester approved at 4 g/d as an adjunct to diet to reduce TG levels in adults with TG levels >499 mg/dL. The objective of the randomized, double‐blind, placebo‐controlled EVAPORATE study is to evaluate the effects of icosapent ethyl 4 g/d on atherosclerotic plaque in a North American population of statin‐treated patients with coronary atherosclerosis, TG levels of 200 to 499 mg/dL, and low‐density lipoprotein cholesterol levels of 40 to 115 mg/dL. The primary endpoint is change in low‐attenuation plaque volume measured by multidetector computed tomography angiography. Secondary endpoints include incident plaque rates; quantitative changes in different plaque types and morphology; changes in markers of inflammation, lipids, and lipoproteins; and the relationship between these changes and plaque burden and/or plaque vulnerability. Approximately 80 patients will be followed for 9 to 18 months. The clinical implications of icosapent ethyl 4 g/d treatment added to statin therapy on CV endpoints are being evaluated in the large CV outcomes study REDUCE‐IT. EVAPORATE will provide important imaging‐derived data that may add relevance to the clinically derived outcomes from REDUCE‐IT.

Progression of noncalcified and calcified coronary plaque by CT angiography in SLE

Premature coronary artery disease remains the major cause of late death in systemic lupus erythematosus (SLE). Coronary artery calcium (CAC) represents an advanced stage of atherosclerosis, whereas noncalcified coronary atherosclerotic plaque (NCP) typically is more prone to trigger acute coronary events. The aim of this study was to assess the stability of NCP over time and identify factors associated with changes in NCP in patients with SLE. CT coronary angiography and calcium scanning were performed at baseline and follow-up in thirty-six SLE patients. Duration between baseline and follow-up NCP assessment ranged from 2 to 8 years. CAC was quantified by the Agatston score and classified as none, low (1-99), moderate (100-299) or high calcium score (300 and above). NCP was quantified based on a previously validated score and classified as none, low (<0.5) or high (0.5+). SLE disease activity was quantified using the SELENA-SLEDAI and physician global assessment indices. To assess the association between quantitative clinical variables and changes in NCP, adjusting for time, we used linear regression models. The group of 36 SLE patients were 75% females, 75% Caucasians, 17% African-Americans, 8% other ethnicities. The mean age of patients was 46.6 years. For NCP, 17/36 (47%) of the patients switched qualitative NCP class (none, low, high) between baseline and follow-up, whereas for CAC only 3/35 (9%) switched qualitative class. Increasing years between assessments were associated with an increase in NCP (P = 0.038). The proportion of time on immunosuppressants was associated with a decrease in NCP (P = 0.06). Calcified coronary plaque levels remained relatively stable over a period of 2-8 years. Noncalcified coronary plaque levels were more variable. Use of immunosuppressive drugs appeared to be protective against noncalcified coronary plaque progression.

Characteristics of high-risk coronary plaques identified by computed tomographic angiography and associated prognosis: a systematic review and meta-analysis

To clarify the potential role of coronary computed tomographic angiography (CCTA) in characterizing and prognosticating high-risk coronary plaques. A systematic review and meta-analysis were conducted to compare high-risk vs. low-risk plaques and culprit vs. non-culprit lesions in patients with acute coronary syndrome (ACS) vs. stable angina (SA). High-risk plaques were defined by at least one of the following features: non-calcified plaque (NCP), the presence of spotty calcified plaque (SCP), or increased remodelling index (RI). Results of included studies were pooled as odds ratios (OR) or weighted mean differences (WMD) with 95% confidence interval (CI). Eighteen eligible studies provided data to compare plaque types, plaque volume, and RI. Six studies provided data on ACS events in vulnerable high-risk vs. low-risk calcified plaques after 35 ± 2 months of follow-up. ACS patients had significantly higher number of NCP and SCP compared with SA patients with OR = 1.96 (1.47-2.60; 95% CI) P = 0.0001 and OR = 4.5 (2.98-6.83; 95% CI) P = 0.0001, respectively. Total plaque volume in ACS was not larger than SA: WMD = 22.9 (-22.1 to 67; 95% CI) mm(3), P = 0.32, but NCP volume was significantly larger: WMD = 28.8 (10.9-46.7; 95% CI) mm(3), P = 0.002. RI was higher in culprit lesions in ACS compared with SA and compared with non-culprit lesions in ACS patients: WMD = 0.48 (0.25-0.70; 95% CI) P = 0.0001 and 0.19 (0.07-0.30) P = 0.0001, respectively. The associated risk of future ACS was significantly higher in high-risk than in low-risk plaques: OR = 12.1 (5.24-28.1; 95% CI) P = 0.0001. CCTA can non-invasively characterize high-risk vulnerable coronary plaques and can predict future ACS events in patients with high-risk plaques.

Persistent epicardial adipose tissue accumulation is associated with coronary plaque vulnerability and future acute coronary syndrome in non-obese subjects with coronary artery disease

Objective. Epicardial adipose tissue (EAT) is recognized as a novel risk factor for coronary artery disease (CAD), and its contribution is thought to be stronger in non-obese patients than in obese patients. However, the prognostic impact of the progression of EAT accumulation after comprehensive management for atherosclerotic risk factors remains unclear. This study aimed to investigate whether an increase of the EAT volume during follow-up predicts future acute coronary syndrome (ACS) events in non-obese CAD patients. Methods. This study consisted of 517 non-obese CAD patients (368 men; age, 66 ± 10 years) who underwent serial multidetector computed tomography (MDCT) examinations to evaluate coronary atherosclerosis progression. The MDCT examination was used to assess the severity of stenosis, plaque characteristics, and EAT volume. All patients received comprehensive management to reduce CAD risk factors after the first MDCT examination. The MDCT examination was repeated at 6-24 months, and patients were followed-up for more than 1 year or until the occurrence of ACS events. Results. Of 517 patients, 159 (31%) patients were classified into increase of EAT volume during follow-up, 91 (18%) into decrease of EAT volume during follow-up, and 267 (51%) patients into constant of EAT volume during follow-up. The prevalence of obstructive plaques and MDCT-derived vulnerable features of coronary plaques were significantly elevated in patients with increase of EAT volume during follow-up. In contrast, no significant changes were observed in the other 2 groups. During the follow-up period of 4.1 ± 1.8 years (median 4.4 years) after the second MDCT examination, ACS occurred in 43 (8.3%) patients. Multivariate Cox regression analysis showed that the presence of low-attenuation plaque (hazard ratio [HR]; 1.78, p = 0.04) and napkin-ring sign (HR; 3.74, p < 0.001) at second MDCT examination, and changes of EAT volume per 10 ml (HR; 1.34, p = 0.004) were associated with future ACS events. Conclusion. Patients with increase of EAT volume during follow-up despite comprehensive management for CAD risks had an increased prevalence of obstructive plaques and plaques with high-risk features, which could be associated with unfavorable ACS outcomes in non-obese CAD patients.

Serum Gamma-glutamyltransferase Levels Predict the Progression of Coronary Artery Calcification in Adults With Type 2 Diabetes Mellitus

Progression of coronary artery calcification (CAC) may be more predictive of future coronary heart disease events than a baseline CAC score. We determined whether serum gamma-glutamyltransferase (GGT) activity can independently predict the progression of CAC in adults with type 2 diabetes mellitus (T2DM). Patients (n = 326) without symptomatic cardiovascular (CV) disease were evaluated by CAC imaging. The CAC scores were assessed at baseline and after 20 ± 4 months. Serum GGT activities were significantly higher in progressors compared with nonprogressors (39 ± 16 vs 27 ± 11 U/L, P < .001). Multivariable analyses demonstrated that GGT activity retained a strong association with CAC progression after adjustment for CV risk factors. Additionally, there was a graded association between GGT activity quartile and annualized CAC progression. In asymptomatic patients with T2DM, we prospectively found that serum GGT activity may be an independent predictor of CAC progression but not a predictor of CAC incidence.

Is visceral fat really a coronary risk factor? A multi-detector computed tomography study

Metabolic syndrome (MS) is currently considered to be a risk factor for arteriosclerotic disease. The accumulation of visceral fat leads to arteriosclerotic disease after other risk factors have developed and either direct or mutual effects occur. The aim of this study was to verify whether visceral fat serves as an independent coronary risk factor. A total of 3157 patients who had undergone multi-detector computed tomography (MDCT) were analyzed via computed tomographic angiography and the measurement of their visceral fat area. Coronary arteries with > 70% stenosis were considered to be significant. The visceral fat area was measured at the umbilical level, and an area of 100 cm2 or more was defined as visceral obesity. Coronary risk factors (ie, hypertension, dyslipidemia, diabetes mellitus, family history, and smoking) were obtained from the patient medical records. The patients were divided into two groups: a visceral obesity group, 1130 patients (137.0 ± 31.1 cm2) and a nonvisceral obesity group, 2027 patients (57.3 ± 25.8 cm2). A significant difference in the incidence of coronary stenosis between the two groups was observed. According to multivariable analysis, the factors affecting coronary stenosis were age, gender, dyslipidemia, diabetes mellitus, and the ratio of visceral to subcutaneous fat. Visceral obesity was not found to be an independent coronary risk factor. Visceral obesity demonstrated the predominant presence of coronary risk factors.

Prognosis of vulnerable plaque on computed tomographic coronary angiography with normal myocardial perfusion image

AIMS

Increasing clinical evidence has emphasized the importance of coronary plaque characteristics, rather than the severity of luminal narrowing on acute coronary syndrome (ACS) outcome. Computed tomographic coronary angiography (CTCA) is a unique, non-invasive approach for assessing plaque characteristics. This study was prospectively designed to investigate the prognostic value of physiologically non-obstructive but a vulnerable coronary plaque on CTCA for predicting future ACS events.

METHODS AND RESULTS

This study consisted of 543 patients who had undergone CTCA and had normal findings on exercise-stress myocardial perfusion single-photon emission computed tomography. CTCA analysis included the presence of >50% luminal stenosis and vulnerable features including positive remodelling (PR), low-attenuation plaque, and ring-like sign. The primary endpoint was ACS events including cardiac death, non-fatal myocardial infarction, and unstable angina. The mean follow-up period was 3.4 ± 0.8 years. The 3-year cumulative event rate was 1.2% per year, and 87% of ACS events occurred in plaques with at least one of vulnerable features. In patient-based multivariate analysis, the presence of plaque with vulnerable features on CTCA was a significant predictor for future ACS events (P = 0.001). Patients with vulnerable plaque had worse ACS outcomes compared with those without vulnerable plaques (3-year cumulative event rate; 3.2 per year vs. 0.8%, P < 0.001).

CONCLUSION

This study demonstrated that physiologically non-obstructive but vulnerable coronary plaques were associated with future ACS events. We should pay more attention to currently non-obstructive plaque but showing vulnerable morphologies on CTCA.

Increased coronary atherosclerotic plaque vulnerability by coronary computed tomography angiography in HIV-infected men

OBJECTIVE

Among HIV-infected patients, high rates of myocardial infarction (MI) and sudden cardiac death have been observed. Exploring potential underlying mechanisms, we used multidetector spiral coronary computed tomography angiography (coronary CTA) to compare atherosclerotic plaque morphology in HIV-infected patients and non-HIV-infected controls.

METHODS

Coronary atherosclerotic plaques visualized by CTA in HIV-infected (101) and non-HIV-infected (41) men without clinically apparent heart disease matched on cardiovascular risk factors were analyzed for three vulnerability features: low attenuation, positive remodeling, and spotty calcification.

RESULTS

Ninety-five percent of HIV-infected patients were receiving ART (median duration 7.9 years) and had well controlled disease (median CD4 cell count, 473 cells/μl; median HIV RNA <50 copies/ml). Age and traditional cardiovascular risk factors were similar in HIV-infected patients and controls. Among the HIV-infected (versus control) group, there was a higher prevalence of patients with at least one: low attenuation plaque (22.8 versus 7.3%, P = 0.02), positively remodeled plaque (49.5 versus 31.7%, P = 0.05) and high-risk 3-feature plaque (7.9 versus 0%, P = 0.02). Moreover, patients in the HIV-infected (versus control) group demonstrated a higher number of low attenuation plaques (P = 0.01) and positively remodeled plaques (P = 0.03) per patient.

CONCLUSION

Our data demonstrate an increased prevalence of vulnerable plaque features among relatively young HIV-infected patients. Differences in coronary atherosclerotic plaque morphology - namely, increased vulnerable plaque among HIV-infected patients - are here for the first time reported and may contribute to increased rates of MI and sudden cardiac death in this population.

How to assess non-calcified plaque in CT angiography: delineation methods affect diagnostic accuracy of low-attenuation plaque by CT for lipid-core plaque in histology

AIMS

To compare the accuracy of two plaque delineation methods for coronary computed tomographic angiography (CTA) to identify lipid-core plaque (LCP) using histology as the reference standard.

METHODS AND RESULTS

Five ex vivo hearts were analysed by CTA and histology. LCP was defined by histology as fibroatheroma with core diameter/circumference >200 μm/>60° and cap thickness <450 μm. In CTA, plaque was manually delineated either as the difference between the inner and outer vessel walls (Method A) or as a direct tracing of plaque (Method B). Low-attenuation plaque was defined as an area with <90 Hounsfield units. Of 446 co-registered cross-sections, 55 (12%) contained LCP. In CTA, low-attenuation plaque area was larger as assessed with Method A compared with Method B (difference: 120 ± 60%). Although low-attenuation plaque was associated with the presence of LCP, the delineation Method B yielded higher diagnostic accuracy than Method A [area under the curve (AUC): 0.831 vs. 0.780, respectively, P = 0.005]. After excluding 'normal' cross-sections by CTA (n = 117), AUC for detecting LCP became similar between both methods (0.767 vs. 0.729, P = 0.07, respectively).

CONCLUSION

Low-attenuation plaque in CTA is a diagnostic tool for LCP but prone to error if plaque is defined as the area between the inner and outer vessel walls and normal cross-sections are included in the assessment.

Napkin-ring sign on coronary CT angiography for the prediction of acute coronary syndrome

OBJECTIVES

The aim of this study was to determine the predictive value of the napkin-ring sign on coronary computed tomography angiography (CTA) for future acute coronary syndrome (ACS) events in patients with coronary artery disease.

BACKGROUND

Recent studies have reported a close association between the napkin-ring sign on coronary CTA and thin-cap fibroatheroma.

METHODS

The subjects of this prospective study were 895 consecutive patients who underwent coronary CTA examination and were followed for >1 year. The primary endpoint was an ACS event (cardiac death, nonfatal myocardial infarction, or unstable angina pectoris). The coronary CTA analysis included the presence of obstructive plaque, positive remodeling (PR), low-attenuation plaque (LAP), and the napkin-ring sign. The napkin-ring sign was defined by the following criteria: 1) the presence of a ring of high attenuation around certain coronary artery plaques; and 2) attenuation of the ring presenting higher than those of the adjacent plaque and no >130 Hounsfield units.

RESULTS

Of the 12,727 segments, 1,174 plaques were observed, including plaques with PR in 130 segments (1.0%), LAP in 107 segments (0.8%), and napkin-ring signs in 45 segments (0.4%). Thirty-six of the 45 plaques with napkin-ring signs (80%) overlapped with those showing either PR or LAP. During the follow-up period (2.3 ± 0.8 years), 24 patients (2.6%) experienced ACS events, and plaques developed in 41% with a napkin-ring sign. Segment-based Cox proportional hazards models analysis showed that PR (p < 0.001), LAP (p = 0.007), and the napkin-ring sign (p < 0.0001) were independent predictive factors for future ACS events. Kaplan-Meier analysis demonstrated that plaques with napkin-ring signs showed a higher risk of ACS events compared with those without a napkin-ring sign.

CONCLUSIONS

The present study demonstrated for the first time that the napkin-ring sign demonstrated on coronary CTA was strongly associated with future ACS events, independent of other high-risk coronary CTA features. Detection of the napkin-ring sign could help identify coronary artery disease patients at high risk of future ACS events.

Distribution, frequency and clinical implications of napkin-ring sign assessed by multidetector computed tomography

BACKGROUND

Plaque rupture and secondary thrombus formation play key roles in the onset of acute coronary syndrome (ACS). Plaques showing the napkin-ring sign in multidetector computed tomography (MDCT) have been reported as thin-cap fibroatheroma that is recognized as a precursor lesion for plaque rupture. The purpose of this study was to investigate distribution and frequency of napkin-ring sign and its relationship to features indicating coronary plaque vulnerability on MDCT in patients with coronary artery disease.

METHODS

We enrolled 273 patients with ACS (n=61) or stable angina pectoris (SAP, n=212) who were assessed by MDCT. The definition of the napkin-ring sign was the presence of a ring of high attenuation and the CT attenuation of a ring presenting higher than those of the adjacent plaque and no greater than 130HU.

RESULTS

The culprit plaques with the napkin-ring sign show higher remodeling index and lower CT attenuation (1.15±0.12 vs. 1.02±0.12, p<0.01 and 39.9±22.8 vs. 72.7±26.6, p<0.01, respectively). Napkin-ring sign at culprit lesions was more frequent in patients with ACS than those with SAP (49.0% vs. 11.2%, p<0.01). Moreover, napkin-ring sign at non-culprit lesions was more frequently observed in ACS patients compared with SAP patients (12.7% vs. 2.8%, p<0.01). The distribution of the napkin-ring sign in the right coronary arteries and left circumflex arteries of our population was relatively even, whereas the napkin-ring sign in the left anterior descending artery was common in the proximal sites (p<0.01).

CONCLUSIONS

The napkin-ring sign assessed by MDCT represents similar clinical features of fibroatheroma. MDCT could contribute to the search for fibroatheroma.

Controlling intracoronary CT number for coronary CT angiography

BACKGROUND

Controlling intracoronary computed tomography (CT) number for coronary CT angiography (CCTA) has been difficult.

OBJECTIVE

The study assessed whether intracoronary CT number of CCTA could be estimated.

METHODS

One hundred twenty six patients were randomly assigned to either CCTA with 30 mL of contrast media (CM) following 5 mL of CM at timing bolus or CCTA with 50 mL of CM following 10 mL of CM at timing bolus. The relationships between intracoronary CT number and patients' characteristics and peak time and peak CT number at timing bolus in patients who showed valid time-density curve were analyzed in both groups. Then, the multiple regression equation best described was made. The prediction system was validated by 112 patients randomly targeted between 250 HU and 430 HU of CT number.

RESULTS

In group 5/30, intracoronary CT number was positively correlated with peak CT number at timing bolus (correlation coefficient, 1.42, p<0.001), negatively correlated with body surface area (-109.19, p<0.001) and peak time (-6.93, p<0.001). Whereas, intracoronary CT number was positively correlated with only peak CT number at timing bolus (1.33, p<0.001) in group 10/50. Then, CT number-controlling system using the simple equation best described CT number was established for CCTA following 5 mL of CM at timing bolus. Of 112 patients, there was good correlation between target CT number and measured CT number (r=0.85, p<0.0001) in 96 patients (85.7%), having valid time-density curve at timing bolus.

CONCLUSIONS

Controlling CT number may be enabled by CT number-controlling system following 5 mL of CM at timing bolus.