CT Coronary Calcium Research Articles

172Coronary 18F-sodium fluoride uptake predicts progression of coronary arterial calcification

Abstract Background Combined positron emission tomography and computed tomography (PET-CT) using 18F-sodium fluoride (18F-NaF) to detect microcalcification provides the opportunity to gain important insights into disease activity in coronary atherosclerosis. However, the relationship between 18F-NaF uptake and progression of coronary calcification has not been determined. Purpose To determine the relationship between 18F-NaF uptake and progression of coronary calcification in patients with clinically stable coronary artery disease (CAD). Methods Patients with established, multivessel CAD underwent 18F-NaF PET-CT and CT coronary calcium scoring at baseline, with repeat CT calcium scoring at one year. Coronary arterial PET uptake was analysed qualitatively and semi-quantitatively in diseased vessels by measuring maximum tissue-to-background ratio (TBRmax) – defined as the maximum standardised uptake value in a plaque divided by mean blood pool activity measured in the right atrium. Coronary calcification was quantified by measuring calcium mass, volume, average calcium density and total Agatston score (AU). Results In total, 185 patients underwent baseline and repeat imaging (median age 66 years, 80% men), and 118 (64%) had increased 18F-NaF uptake in at least one vessel. Median total calcium score, volume, mass and average density were higher in patients with compared to those without increased 18F-NaF uptake (Table 1). At one year, patients with evidence of increased 18F-NaF uptake demonstrated more rapid progression of coronary calcification (97 [39–166] AU) versus those without uptake (35 [7–93] AU; p<0.0001). Amongst 18F-NaF-positive patients, the calcium score increased only in coronary segments with 18F-NaF uptake (baseline 90.5 [27.5–202] AU versus one year 135.5 [59.3–281.8] AU; p<0.0001) and not in 18F-NaF-negative segments (baseline 44.5 [16–110.5] AU versus one year 46.5 [18.25–114] AU; p=0.446). There was a moderate correlation between TBRmax and change in total calcium score, volume and mass at 1 year (Spearman's Rho = 0.37, 0.38, 0.46 respectively; p<0.0001 for all). Coronary calcification at baseline in PET-negative and PET-positive patients All patients (n=185) 18F-NaF Positive (n=118) 18F-NaF Negative (n=67) P value Agatston Score (AU) 381 [107–892] 541 [245–1130] 136 [55–361] p<0.0001 Calcium Volume (mm3) 358 [131–787] 506 [251–1014] 131 [64–343] p<0.0001 Calcium Mass (mg) 71 [23–155] 100 [48–222] 24 [11–69] p<0.0001 Average Density (mg/mm3) 0.19 [0.17–0.22] 0.20 [0.18–0.23] 0.18 [0.16–0.20] p<0.0001 Conclusions Coronary 18F-NaF uptake identifies both patients and individual coronary segments with greater disease and more rapid progression of coronary calcification over one year. Acknowledgement/Funding AstraZeneca (unrestricted educational grant). British Heart Foundation (CH/09/002, RE/13/3/30183, FS/17/79/33226) Wellcome Trust (WT103782AIA).

Coronary CT Calcium Score in Patients With Prior Nongated CT, Is it Necessary?

PurposeTo evaluate the percentage of patients undergoing gated coronary artery calcium score CTs that had a prior nongated chest CT. To assess the accuracy of prior nongated chest CTs in the detection of coronary calcium. BackgroundCardiovascular disease is the most common cause of death worldwide. Quantifying coronary artery calcification on gated calcium score CT has proven to be strongly predictive of adverse coronary artery disease events. However, visual estimation and ordinal scoring on nongated chest CTs is predictive of coronary calcium burden. MethodsConsecutive gated calcium score CTs at a single institution from 10/2014 to 10/2016 were retrospectively evaluated with IRB approval/waiver of informed consent. The presence or absence of coronary calcium and ordinal score on nongated chest CT was compared to Agatston score on gated calcium score CT. ResultsForty-two of 441 patients (9.5%) with a gated calcium score had a prior nongated chest CT, with a mean time difference of 810 days. Of the 42 prior chest CTs, 69% had coronary artery calcium (CAC) and 31% did not, with 100% predictive accuracy for the presence or absence of CAC on subsequent gated calcium score CTs. There was 86% correlation of Agatston score on gated calcium score CT with ordinal score on the prior chest CT. Ordinal score divided into independent groups of severity was related to increased severity of Agatston score on the gated calcium score CT (P< 0.001). A majority of prior chest CT studies with coronary calcium failed to include this information in the final report. ConclusionsA large percentage of gated calcium score CTs were performed despite a prior chest CT. The ordinal score on chest CTs correlated with Agatston score on gated calcium score CTs. The presence of CAC on chest CTs was underreported in a majority of cases.

SUN-060 Statin-Resistant Hyperlipidemia: Role of Lipoprotein (a)

BACKGROUND: Statin resistance is a term used to describe failure to reach LDL-cholesterol target values despite high dose statin therapy. Common causes for this is nonadherence to therapy and polymorphisms in mechanisms that involve lipid absorption and metablism. We report a case of a patient with resistance to high statin therapy found to have elevated lipoprotein a [Lp(a)]. CLINICAL CASE: A 30 year old Caucasian male presented with hyperlipidemia. He was diagnosed since age of 16 and reports failure to “multiple cholesterol medications”. He had a normal EKG and stress test in the past. Denies prior history of coronary events, peripheral vascular disease or stroke. Currently only medication is atorvastatin 40 mg daily which was recently started when establishing care with new PCP. Otherwise, he was not on any lipid lowering medication for the past 6 months. He adheres to low fat diet. The patient’s body mass index is 25.6. Physical exam is benign including no xanthomas, intact pulses bilaterally, and extremities warm to touch. Labs reveal normal liver function tests, TSH 1.979, HbA1c 5.2% and Lp(a) 169 nmol/L (reference < 75 nmol/L). Lipid profile without statin therapy: total cholesterol 490, triglyceride 146, HDL 52, LDL 409. After 2 months of statin therapy: total cholesterol 448, triglyceride 127, HDL 58, LDL 370. A CT coronary calcium study revealed moderate plaque on left anterior descending artery with CAC score 104.15 suggesting atherosclerotic process. DISCUSSION: The metabolism and function of Lp(a) is still not completely understood but it is known to be a risk factor for coronary heart disease, stroke, and peripheral artery disease. Lp(a) closely resembles an LDL particle with the addition of the very large apolipoprotein (a) linked onto apolipoprotein B100 by a disulfide bond. There is structural similarity between apo(a) and plasminogen and is proposed as the missing link between atherosclerosis and thrombosis. Reduced caloric intake can decrease Lp(a) but low fat diet does affect Lp(a) levels. Aspirin reduces Lp(a) by up to 80% and itself is reduces the risk of ASCVD events. Niacin has been shown to reduce Lp(a) and adverse effects can be better tolerated with aspirin but risk reduction has not been proven. PSCK9 inhibitors are newer drugs that markedly lower LDL and can modestly lower Lp(a). CONCLUSION: Statin therapy remains the foundation treatment in patients with hyperlipidemia and elevated Lp(a) despite little effect of Lp(a) due to its ability to lower ASCVD risk. Additional pharmacological agents including aspirin & PSCK9 inhibitors can be a useful adjuncts to reduce ASCVD risk despite modest Lp(a) reduction. Lipoprotein apheresis may be used in refractory cases.

A CASE OF BIGEMINY AND SUCCESSFUL COMPLETION OF ACUTE ELECTROCONVULSIVE THERAPY COURSE

Introduction Electroconvulsive therapy (ECT) remains stigmatized in the broader medical community due to misunderstandings about treatment procedures, mortality rates, and cardiovascular complications. Several concerns have risen regarding the safety of ECT on the cardiovascular system. ECT causes periprocedural hemodynamic variability due to the surges in parasympathetic and sympathetic nervous systems following the administration of the electric current.1 Patients experience an increase in cardiac workload and oxygen demand, which is potentially dangerous for patients with preexisting heart disease. Several findings suggest the incidence of cardiac complications is relatively rare and occurs most frequently in patients with underlying cardiovascular disease. Methods We describe a case report of a 53 year old female with history of bipolar I disorder current episode depressed, hyperlipidemia undergoing ECT who developed cardiovascular complications after her seventh brief pulse right unilateral (BRUL) treatment. Electrocardiogram (EKG) monitoring revealed bigeminy for two to three minutes (heart rate in 80s) during post-anesthesia care. Results The cardiovascular system undergoes various changes during ECT including events secondary to the parasympathetic release such as asystole, hypotension, bradycardia, and events secondary to sympathetic release such as hypertension and tachycardia. Other complications include arrhythmias, ST elevation, and Takotsubo Cardiomyopathy. The patient was seen by cardiology for further work-up. EKG, 2-D cardiac echocardiogram, 48-hour Holter monitoring, and coronary CT calcium scan were performed. She was found to have rare premature atrial contractions (PACs) (8 in 48 hours). Her bigeminy resolved spontaneously. The patient was able to complete the acute course of BRUL ECT and continued onto maintenance ECT with good effect. We also present a table with the common cardiovascular side effects from ECT and the most recent evidence-based treatment strategies to manage them. Conclusions Generally, ECT is a safe procedure; complications are minor and manageable. Most major complications caused by ECT are related to the cardiovascular system; however, with an appropriate pre-ECT evaluation and a comprehensive multidisciplinary-team approach the cardiovascular complications can be well managed and minimized. Our case highlights the benefits of a multidisciplinary care model between psychiatry, anesthesia, and cardiology. Providing proper cardiac clearance can prevent cardiac complications and provide timely care to treatment-resistant populations who are at risk for excessive morbidity and suicide. This research was funded by None.

Subclinical Left Ventricular Dysfunction and Coronary Artery Disease: A Strained Relationship?

Background: Subclinical disease evidences early pathology and may select for early intervention. CT coronary calcium scoring (CCS) shows that preclinical coronary artery disease (CAD) and echocardiography-derived abnormal global longitudinal strain (GLS), left ventricular hypertrophy (LVH) and diastolic dysfunction (DD) are markers of preclinical heart failure. We studied whether these disease entities overlap. Methods: This sub-study of CAUGHT-CAD comprised community-recruited, asymptomatic and statin-naïve individuals, 40–70 yo with a family history of premature CAD. Participants underwent detailed clinical assessment, CT CCS and echocardiography. Subclinical CAD was defined as CCS >0. Subclinical LV dysfunction (Sub-LVD) by (a) DD: E/e’>15 or E/e’ 10–15 with left atrial enlargement (LAVi >35 ml/m2); (b) systolic dysfunction (SD) (GLS <16% or GLS 16–18% with LAE). Results: 125 patients were studied with a mean age of 60, 69 (55%) were female and 63 (50%) had CCS >0. Sub-LVD was present in 12 (10%) with CCS >0 in 7, compared to 56 of 113 without LVD (58% vs 50%, p = 0.78). 11 of 24 participants had abnormal GLS (46% vs 51%, p = 0.66). With univariable analysis, older age, male sex and Framingham were associated with CCS >0 but not S-LVD. Conclusion: Among pts >40 yo with risk factors, subclinical CAD and LVD are likely unrelated entities. Traditional CVD risks poorly stratify for subclinical LVD, and heart failure-specific scores may be more appropriate.Tabled 1CCS > 0OR (95%CI)Sub-LVDOR (95%CI)Age1.08 (1.06,1.10)1.02 (0.64,1.10)Male2.33 (1.82, 3.00)1.27 (0.44,3.63)FRS1.11 (1.05, 1.18)1.03 (0.97,1.10)BMI0.99 (0.97, 1.02)0.94 (0.83,1.07) Open table in a new tab Tabled 10 CCSn = 62+ CCSn = 63pAge58 ± 758 ± 7<0.05FRS9 ± 513 ± 9<0.05GLS19 ± 220 ± 20.14E/e’7 ± 27 ± 20.51LAVi31 ± 1131 ± 110.92LVMi74 ± 1576 ± 170.55S-LVD4 (6%)7 (11%)0.36 Open table in a new tab

Positive association of lipoprotein(a) with ct coronary calcium score in asymptomatic caucasians but not in other ethnicities

Positive association of lipoprotein(a) with ct coronary calcium score in asymptomatic caucasians but not in other ethnicities

The Role of Coronary CT Calcium as a Stand-Alone Screening Tool for Coronary Artery Disease in a Younger Multi-Racial Asian Population

The Role of Coronary CT Calcium as a Stand-Alone Screening Tool for Coronary Artery Disease in a Younger Multi-Racial Asian Population

Iterative beam-hardening correction with advanced modeled iterative reconstruction in low voltage CT coronary calcium scoring with tin filtration: Impact on coronary artery calcium quantification and image quality

ObjectiveWe investigated the impact of iterative beam-hardening correction (IBHC) with advanced modeled iterative reconstruction (ADMIRE) of ultra-low radiation-dose tin filtered (Sn100 kVp) CACS acquisitions on image quality, calcium quantification, and risk classification. MethodsCT data of 60 patients (55% male, age 62.3 ± 9.8years) who underwent a 3rd generation dual-source CACS scan using a prospectively ECG-triggered 100 kVp sequential acquisition protocol with tin filtration (Sn100 kVp) were reconstructed using IBHC with filtered back projection (FBP) and ADMIRE with strength levels of three and five. Image noise was calculated and Agatston scores were derived from all reconstructions. Image noise, Agatston score categories, and percentile-based cardiac risk categorization of the respective reconstruction techniques were compared. ResultsThe mean estimated radiation dose equivalent of CACS acquisitions in the study population was 0.20 ± 0.07 mSv. Mean image noise significantly decreased with ADMIRE compared to FBP (both p < 0.0001). Agatston scores derived from the respective reconstructions were significantly different in a paired comparison (median [25th and 75th percentile]): FBP 34.7 [1.9, 153.6], ADMIRE 3 28.6 [1.1, 134.5], ADMIRE 5 22.7 [0.3, 116.8]; both p < 0.0001). Agatston score categories and cardiac risk categorization showed excellent agreement of ADMIRE 3 and ADMIRE 5 with FBP (ĸ = 0.92 [0.86–0.98] and ĸ = 0.86 [0.79–0.94]; ĸ = 0.94 [0.87–1.00] and ĸ = 0.91 [0.83–0.99]; however, modest cardiac risk reclassifications of 3% and 7% for ADMIRE 3 and ADMIRE 5, respectively, were observed. ConclusionIterative reconstruction using IBHC ADMIRE in low voltage, ultra-low dose CACS with tin filtration significantly decreased image noise. However, it also reduced Agatston scores compared to FBP, which may have an impact on subsequent cardiac risk classification, although risk reclassification occurred only in a modest number of subjects.

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 8years. 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 46.6years. 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 2-8years. Noncalcified coronary plaque levels were more variable. Use of immunosuppressive drugs appeared to be protective against noncalcified coronary plaque progression.

The CT coronary calcium score in familial hypercholesterolaemia: Comparison between patients with FH mutations and those with no identified mutation

The CT coronary calcium score in familial hypercholesterolaemia: Comparison between patients with FH mutations and those with no identified mutation

Non-Invasive Fractional Flow Reserve Estimation with Coronary Computed Tomography Angiography

Coronary computed tomography calcium score and angiography has emerged as a powerful tool in the investigation of patients with chest pain Coronary computed tomography calcium score provides both diagnostic as well as prognostic information but in the presence of intermediate coronary lesions neither coronary CT calcium score nor CT angiography is able to determine whether such a lesion is functionally significant Fractional flow reserve coronary CT angiography has emerged as a novel non invasive technique for the assessment of intermediate atherosclerotic coronary artery lesions

Novel SPECT Technologies and Approaches in Cardiac Imaging

Recent novel approaches in myocardial perfusion single photon emission CT (SPECT) have been facilitated by new dedicated high-efficiency hardware with solid-state detectors and optimized collimators. New protocols include very low-dose (1 mSv) stress-only, two-position imaging to mitigate attenuation artifacts, and simultaneous dual-isotope imaging. Attenuation correction can be performed by specialized low-dose systems or by previously obtained CT coronary calcium scans. Hybrid protocols using CT angiography have been proposed. Image quality improvements have been demonstrated by novel reconstructions and motion correction. Fast SPECT acquisition facilitates dynamic flow and early function measurements. Image processing algorithms have become automated with virtually unsupervised extraction of quantitative imaging variables. This automation facilitates integration with clinical variables derived by machine learning to predict patient outcome or diagnosis. In this review, we describe new imaging protocols made possible by the new hardware developments. We also discuss several novel software approaches for the quantification and interpretation of myocardial perfusion SPECT scans.

Comparing the cost-effectiveness of four novel risk markers for screening asymptomatic individuals to prevent cardiovascular disease (CVD) in the US population

BackgroundHigh sensitivity CRP (hsCRP), coronary artery calcification on CT (CT calcium), carotid artery intima media thickness on ultrasound (cIMT) and ankle-brachial index (ABI) improve prediction of cardiovascular disease (CVD) risk, but the benefit of screening with these novel risk markers in the U.S. population is unclear. Methods and resultsA microsimulation model evaluating lifelong cost-effectiveness for individuals aged 40–85 at intermediate risk of CVD, using 2003–2004 NHANES-III (N=3736), Framingham Heart Study, U.S. Vital Statistics, meta-analyses of independent predictive effects of the four novel risk markers and treatment effects was constructed. Using both an intention-to-treat (assumes adherence <100% and incorporates disutility from taking daily medications) and an as-treated (100% adherence and no disutility) analysis, quality adjusted life years (QALYs), lifetime costs (2014 US $), and incremental cost-effectiveness ratios (ICER in $/QALY gained) of screening with hsCRP, CT coronary calcium, cIMT and ABI were established compared with current practice, full adherence to current guidelines, and ubiquitous statin therapy. In the intention-to-treat analysis in men, screening with CT calcium was cost effective ($32,900/QALY) compared with current practice. In women, screening with hsCRP was cost effective ($32,467/QALY). In the as-treated analysis, statin therapy was both more effective and less costly than all other strategies for both men and women. ConclusionsWhen a substantial disutility from taking daily medication is assumed, screening men with CT coronary calcium is likely to be cost-effective whereas screening with hsCRP has value in women. The individual perceived disutility for taking daily medication should play a key role in the decision.

The use of CT coronary calcium score in asymptomatic patients with familial hypercholesterolaemia

Background: Familial hypercholesterolaemia (FH) is associated with accelerated atherosclerosis. Diagnosis is based on clinical scores and only 45% of those with a clinical diagnosis have a genetic mutation known to be associated with FH. Coronary artery calcium (CAC) scoring can be used as a surrogate marker for coronary artery disease, but data on its use in FH are scarce. Methods: CAC was performed in 52 asymptomatic patients (16 ‘probable FH’ and 36 ‘possible FH’) classified according to modified Simon Broome criteria, who were attending a secondary care lipid clinic. Demographic and disease characteristics, CAC (Agatston) scores and arterial age were audited. Results: Half the patients had an Agatston score of zero. In those with Agatston scores >0 and age >45 years, the mean arterial age was significantly higher than the chronological age (72 versus 59 years; p=0.0001). Only diabetes and hypertension status were significantly different between those with Agatston scores of 0 and >0 (p=0.045 and p=0.0175 respectively). Arterial age provided information useful for individualised clinical management. Conclusions: Atherosclerosis burden varies widely in FH with diabetes mellitus and hypertension appearing to contribute. We have found the information from CT calcium scoring very useful in identifying those patients with significant atherosclerosis who would need more intensive treatment.

The use of CT coronary calcium score in asymptomatic patients with familial hypercholesterolaemia

The use of CT coronary calcium score in asymptomatic patients with familial hypercholesterolaemia

To assess vascular calcification in the patients of hypoparathyroidism using multidetector computed tomography scan.

Background:Our pilot data showed an increased intima media thickness in the patients with sporadic idiopathic hypoparathyroidism (SIH). Alteration in homeostasis of calcium, phosphate, and parathyroid hormone (PTH) may predispose to increase the risk of cardiovascular morbidity and mortality. The data on objective assessment of this increased risk is however lacking.Objective:To assess the effect of altered calcium, phosphate, and PTH homeostasis in the patients with SIH on coronary calcium score (a marker of increase vascular risk) by multidetector computed tomography scan (MDCT).Methods:In this case-control study, we measured coronary CT calcium score in 30 patients of SIH and compared with 40 age and sex matched healthy subjects. Correlation of coronary calcium score with biochemical parameters was evaluated.Results:Three of the 30 cases (10%) with SIH were found to have coronary artery calcification (CAC) of varying degree, whereas none of the control showed CAC (P = 0.07). The patients with CAC had significantly lower serum calcium levels (albumin corrected), as compared to the patients without CAC. Inverse correlation of CAC was found with serum calcium levels. No correlation was found with other biochemical parameters.Conclusion:The vascular risk is increased in the patients with SIH as assessed by coronary calcium score measured by MDCT. Low serum calcium levels might be a predisposing factor for this increased risk.

Coronary calcification with no flow limiting lesions: A potential cause for ischaemic dysfunction in syndrome X patients

AimExertional angina in patients with no coronary flow limiting lesions remains a clinical puzzle. We aimed to assess the extent of coronary artery calcification (CAC) and its relationship to ventricular wall motion function using stress echocardiography in a group of patients limited by exertional angina, but no obstructive lesions. MethodsWe compared CT coronary calcium score (CACS) and dobutamine stress echocardiography in 55 patients (age 64.7±7.7years), divided into Group 1 (CACS≤100) and Group 2 (CACS>100). No patient had LV ejection fraction-EF<55%, pulmonary hypertension, arrhythmia, renal failure or parathyroid disease. Multiple linear regression analysis was used to test the association between gender-standardized continuous echocardiographic parameters and patient groups adjusted for age, body surface area, osteoporosis and CV risk factors and CACS. ResultsAt rest, LV long axis ‘subendocardial’ function was reduced (amplitude: β −1.11 SD, p<0.05, R2 0.6 and systolic velocity: β −1.08 SD, p<0.05, R2 0.44), left atrial (LA) indexed volume was raised (β 1.06 SD, p<0.05, R2 0.37) and its systolic velocity decreased (β −1.05 SD, p<0.05, R2 0.35) in Group 2. With stress, wall motion score index increased (p<0.05) and long axis disturbances worsened only in the same group. Multivariate analysis demonstrated clear relationship between ischaemic LV disturbances, reduced long axis amplitude, global longitudinal systolic strain and early diastolic strain rate. Resting and stress RV lengthening velocity also correlated with CAC score. ConclusionIn symptomatic patients with no obstructive coronary lesions and with more than mild CAC, long axis disturbances and wall motion score index rise occur with stress, at the time of symptom development and correlate with severity of arterial calcification. These findings suggest CAC as a potential mechanism for coronary wall stiffness and consequently exertional ischaemic changes as a result of limited flow reserve.

Predictive Value of Updating Framingham Risk Scores with Novel Risk Markers in the U.S. General Population

BackgroundAccording to population-based cohort studies CT coronary calcium score (CTCS), carotid intima-media thickness (cIMT), high-sensitivity C- reactive protein (CRP), and ankle-brachial index (ABI) are promising novel risk markers for improving cardiovascular risk assessment. Their impact in the U.S. general population is however uncertain. Our aim was to estimate the predictive value of four novel cardiovascular risk markers for the U.S. general population.Methods and FindingsRisk profiles, CRP and ABI data of 3,736 asymptomatic subjects aged 40 or older from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 exam were used along with predicted CTCS and cIMT values. For each subject, we calculated 10-year cardiovascular risks with and without each risk marker. Event rates adjusted for competing risks were obtained by microsimulation. We assessed the impact of updated 10-year risk scores by reclassification and C-statistics. In the study population (mean age 56±11 years, 48% male), 70% (80%) were at low (<10%), 19% (14%) at intermediate (≥10–<20%), and 11% (6%) at high (≥20%) 10-year CVD (CHD) risk. Net reclassification improvement was highest after updating 10-year CVD risk with CTCS: 0.10 (95%CI 0.02–0.19). The C-statistic for 10-year CVD risk increased from 0.82 by 0.02 (95%CI 0.01–0.03) with CTCS. Reclassification occurred most often in those at intermediate risk: with CTCS, 36% (38%) moved to low and 22% (30%) to high CVD (CHD) risk. Improvements with other novel risk markers were limited.ConclusionsOnly CTCS appeared to have significant incremental predictive value in the U.S. general population, especially in those at intermediate risk. In future research, cost-effectiveness analyses should be considered for evaluating novel cardiovascular risk assessment strategies.

Molecular imaging of coronary atherosclerosis; predictive of an acute myocardial infarction?

Coronary atherosclerosis is a leading cause of cardiovascular morbidity and mortality worldwide. Plaque complications occur most commonly from plaque rupture, and also from plaque erosion and calcified nodule formation. Over the past years, advanced structural, metabolic and molecular imaging technologies have emerged and offer new windows into atherosclerosis pathophysiology [1–4]. Molecular imaging complements traditional structural plaque imaging through the use of targeted probes that identify specific molecules and/or biological processes in vivo [5]. Preclinical atherosclerosis molecular imaging has successfully identified nearly all established high-risk plaque characteristics including inflammation, thrombosis, neo-vessel formation, apoptosis, and haemorrhage. However, clinical translation of molecular imaging has been slow compared with the rapid growth within the field. Currently, clinical atherosclerosis molecular imaging is dominated by non-invasive PET metabolism/inflammation plaque imaging with fluorine 18 (18F)-fluorodeoxyglucose (FDG). For the past two decades, 18F FDG has been the only fluorine-18 radioligand approved by the US Food and Drug Administration (FDA) for PET imaging. Coronary FDG PET is challenging, in part owing to the small size of coronary vessels and cardiac motion artefacts, but also because of the intense FDG uptake of the adjacent highly metabolic myocardium that obscures the coronary FDG signal. However, with dietary myocardial suppression protocols, detection of FDG PET signal in the left main and proximal coronary artery beds is sometimes achievable. Recently, non-invasive coronary FDG PET activity has been investigated in the stented culprit lesions of 20 subjects with acute coronary syndromes (ACS) versus seven non-ACS subjects within 1 week of stent placement [6]. Using a predetermined FDG target to background ratio of 2.0 or greater to identify FDG-positive lesions, the ACS patients correlated positively with elevated stent FDG signal. However, coronary FDG signal was interpretable in only 50 % of ACS patients, implying the need for further improvements in coronary FDG PET. Apart from 18F FDG coronary imaging, clinically available approaches such as sodium 18F-fluoride (NaF) for PET are emerging. Coronary calcification is a hallmark of advanced atheroma that can be detected with non-invasive NaF PET, which has been used for the past 3 decades to detect cancer bone metastases. As opposed to FDG, background myocardial uptake of NaF is negligible, and therefore NaF can determine coronary osteogenic activity. In a study by Dweck et al. from the University of Edinburgh [7], NaF PET molecular imaging identified sites of active coronary calcification non-invasively by PET and may be a new therapeutic target. The NaF signal was elevated in proportion to coronary CT calcium scores in 119 subjects, except in those with the highest calcium scores that may represent end-stage calcified plaques. From the same research group, Joshi et al. [8] recently (Lancet November 2013) studied coronary plaque imaging using two different radioactive tracers: 18F-NaF and 18F-FDG. The Scottish study included 40 patients with acute myocardial infarction (AMI) and 40 patients with stable angina. All patients underwent PET-CT, invasive coronary angiography, CT coronary angiography, and CT calcium scoring. Among the 40 patients with AMI, 18F-NaF PET uptake was 34 % higher in the culprit ruptured plaque compared with non-culprit plaques. Nearly all patients (93 %) had increased 18F-NaF uptake in the culprit plaque. With 18F-FDG, however, no differences in uptake between culprit and non-culprit plaques were observed. Among the 40 patients with stable angina, 45 % had plaques with increased 18F-NaF uptake. These plaques were mostly non-obstructive at coronary angiography and contained more high-risk features on intravascular ultrasound compared with plaques without tracer uptake. Consequently, 18F-NaF PET may become an effective tool for predicting an AMI, which would have a great impact for patients with coronary atherosclerosis. Early detection of the atherosclerotic ‘danger zones’ could include immediate instalment of drugs such as statins or aspirin, drastic changes in lifestyle and even inserting stents into the affected coronary artery. The use of 18F-NaF PET-CT offers the first non-invasive imaging method to identify and localise ruptured and high-risk coronary plaques. A next step is to show that increased 18F-NaF predicts future adverse clinical events. Further studies are therefore needed to evaluate whether the detection of risky plaques before rather than after an AMI has the potential to save lives. To summarise, the addition of newer molecular imaging tools such as NaF PET-CT will continue to strengthen our understanding of the in vivo biology of high-risk plaques [9, 10]. They are increasingly being translated into clinical use, and in combination with structural imaging they provide more comprehensive information to build risk-prediction tools. Ongoing efforts to improve non-invasive coronary imaging strategies must be pursued. Overall, with continued advances in molecular and structural atherosclerosis imaging, high-risk coronary atherosclerotic plaques will be brightened as never before. The recent study in the Lancet at least suggests that molecular imaging using PET-CT scanning may provide an answer in identifying ‘ticking time bomb’ patients at risk of an AMI.

Organ dose and scattering dose for CT coronary angiography and calcium scoring using automatic tube current modulation

Noninvasive coronary angiography and calcium scoring with the use of multi-detector computed tomography scanners are feasible for reliably detecting coronary artery disease. The purpose of this study is to investigate organ dose and scattering dose for CT coronary angiography and calcium scoring using automatic tube current modulation. Organ doses of an anthropomorphic phantom were estimated using LiF:Mg,Cu,P thermoluminescent dosimeter (TLD) chips. The dose profiles inside and outside the scanning regions were measured. Effective doses for coronary angiography and calcium scoring without using automatic tube current modulation are respectively 12.72 ± 2.06 and 1.69 ± 0.30 mSv. Using automatic tube current modulation can reduce effective dose by 43% for coronary angiography, and 24–32% for calcium scoring. Scatter doses at the point of 10 cm away from the margin of scanning region decreased to 5–9% of in-plane doses. Using automatic tube current modulation can effectively reduce radiation doses inside the CT scanning region.