Transmural Myocardial Scar Assessed by Cardiac Computed Tomography: Predictor of Echocardiographic Versus Clinical Response to Cardiac Resynchronization Therapy?

OBJECTIVES: Before cardiac resynchronization therapy (CRT) implantation, cardiac computed tomography (CT) can provide assessment of cardiac venous anatomy and visualize left ventricular (LV) myocardial scar. We hypothesized that localization and burden of transmural myocardial scar verified by cardiac CT are associated with echocardiographic and clinical response to CRT. METHODS: We prospectively included 140 CRT recipients undergoing preimplant cardiac CT. We assessed transmural scar, defined as hypoperfusion involving more than one-half of the myocardial wall in each LV segment using a 17-segment model. Echocardiographic nonresponse was defined as less than 5% absolute improvement in LV ejection fraction at 6 months' follow-up. Clinical nonresponse was defined as 1 or more of the following at 6 months' follow-up: death, heart failure hospitalization, or no improvement in New York Heart Association class and less than 10% increase in 6-minute walk-test distance. RESULTS: Higher burden of myocardial scar was associated with echocardiographic nonresponse (adjusted odds ratio, 3.02; 95% confidence interval, 1.03-8.91; P = 0.045). Scar concordant or adjacent to LV pacing site was associated with echocardiographic nonresponse (adjusted odds ratio, 8.2; 95% confidence interval, 1.51-44.27; P = 0.015). No association between scar and clinical nonresponse was demonstrated. CONCLUSIONS: Higher scar burden and scar in proximity to the LV pacing site assessed by cardiac CT are associated with echocardiographic nonresponse to CRT. Burden and location of scar were not associated with clinical nonresponse. Further large-scale studies are needed to assess the potential association between myocardial scar detected by cardiac CT and clinical CRT outcome.

Coronary artery calcium assessed with calibrated mass scoring in asymptomatic individuals: results from the Copenhagen General Population Study.

BACKGROUND: Coronary artery calcification (CAC) is commonly assessed with Agatston score (AS). A higher sensitivity and precision for the detection of CAC has been demonstrated with calibrated mass score (cMS). We hypothesized that cMS would detect low-level CAC not detectable with AS in a large asymptomatic background population. METHODS: Participants (N = 2985) from the Copenhagen General Population Study were evaluated for CAC using both conventional AS and cMS. The population was grouped according to number of traditional risk factors and heart score was used to assess the risk of event for those with no CAC, those with only cMS > 0 and those with both AS and cMS > 0. RESULTS: In participants with an AS = 0, 11% had cMS > 0. The risk profile of this cMS-only group was between that of the CAC-negative participants and those with AS > 0 and cMS > 0. Overall, 6% of the population belonged to the cMS-only group independent of the number of risk factors. CONCLUSION: In individuals with AS = 0, a fraction was found to have cMS > 0. Based on traditional risk factors, this group has a higher 10-year risk than individuals with both AS = 0 and cMS = 0; cMS might offer very early cardiovascular risk assessment in asymptomatic individuals. KEY POINTS: • In individuals with AS=0, a fraction has CAC with highly sensitive cMS. • This fraction has a higher 10-year risk of cardiovascular disease. • Regardless of risk factors, 6% has CAC detectable only with cMS. • cMS might offer very early cardiovascular risk assessment in asymptomatic individuals.

Subtraction CT angiography improves evaluation of significant coronary artery disease in patients with severe calcifications or stents-the C-Sub 320 multicenter trial.

OBJECTIVES: Diagnostic accuracy of conventional coronary CT angiography (CCTAconv) may be compromised by blooming artifacts from calcifications or stents. Blooming artifacts may be reduced by subtraction coronary CT angiography (CCTAsub) in which non-contrast and contrast CT data sets are subtracted digitally. We tested whether CCTAsub in patients with severe coronary calcification or stents reduces the number of false-positive stenosis evaluations compared with CCTAconv. METHODS: In this study, 180 symptomatic patients scheduled for invasive coronary angiography (ICA) were prospectively enrolled and CT scanned (2013-2016) at three international centers. CCTAconv, and CCTAsub data sets were reconstructed. Target segments were defined as motion-free coronary segments with a suspected stenosis (> 50% of lumen) potentially due to blooming of either calcium or stents. Target segments were evaluated with respect to misregistration artifacts from the CCTAsub reconstruction process, in which case evaluation was omitted. CCTAsub and CCTAconv were compared with ICA. Primary outcome measure was the frequency of false positives by CCTAconv versus CCTAsub to identify > 50% coronary stenosis by ICA on a per-segment level. RESULTS: After exclusion of 76 patients, 104 (14% females) with mean age 67 years and median Agatston score 852 were included. There were 136 target segments with misregistration and 121 target segments without. Accuracy calculations in target segments without misregistration showed a reduction of the false positives from 72% [95% confidence interval (CI): 63-80%] in CCTAconv to 33% (CI:25-42%) in CCTAsub, at the expense of 7% (CI:3-14%) false negatives in CCTAsub. CONCLUSIONS: In severely calcified coronary arteries or stents, CCTAsub reduces the false-positive rate in well-aligned, calcified or stent segments suspected of significant stenosis on CCTAconv. Nevertheless, misregistration artifacts are frequent in CCTAsub. KEY POINTS: • A high calcium-score reduces the diagnostic accuracy in patients scanned with cardiac CT. • These patients would normally need an invasive angiogram for diagnosis. • In this prospective, multicenter study, subtraction CT, when evaluable, reduces false-positive stenosis evaluations. • Subtraction coronary CT angiography may, when evaluable, reduce excessive downstream testing.

Coronary CT angiography in clinical triage of patients at high risk of coronary artery disease.

OBJECTIVES: To test if cardiac computed tomography angiography (CCTA) can be used in the triage of patients at high risk of coronary artery disease. DESIGN: The diagnostic value of 64-detector CCTA was evaluated in 400 patients presenting with non-ST segment elevation myocardial infarction using invasive coronary angiography (ICA) as the reference method. The relation between the severity of disease by CCTA and a combined endpoint of death, re-hospitalization due to new myocardial infarction, or symptom-driven coronary revascularization was assessed. RESULTS: CCTA detects significant (>50%) coronary artery diameter stenosis with a sensitivity, specificity, and positive and negative predictive value of 99%, 81%, 96% and 95%, respectively. CCTA was used to triage patients into guideline defined treatment groups of "no or medical treatment", "referral to percutaneous coronary intervention" or to "coronary artery bypass graft surgery" and was compared to the index ICA. CCTA correctly triaged patients in 86% of cases. During a median follow-up of 50 months, the presence of an occluded artery by CCTA was associated with adverse outcome. CONCLUSION: CCTA has high diagnostic and prognostic value in patients with high likelihood of coronary artery disease and could, in theory, be used to triage high risk patients. As many obstacles remain, including logistical and safety issues, our study does not support the use of CCTA as an additional diagnostic test before ICA in an all-comer NSTEMI population.

Myocardial perfusion 320-row multidetector computed tomography-guided treatment strategy for the clinical management of patients with recent acute-onset chest pain: Design of the CArdiac cT in the treatment of acute CHest pain (CATCH)-2 randomized controlled trial.

AIMS: Patients admitted with chest pain are a diagnostic challenge because the majority does not have coronary artery disease (CAD). Assessment of CAD with coronary computed tomography angiography (CCTA) is safe, cost-effective, and accurate, albeit with a modest specificity. Stress myocardial computed tomography perfusion (CTP) has been shown to increase the specificity when added to CCTA, without lowering the sensitivity. This article describes the design of a randomized controlled trial, CATCH-2, comparing a clinical diagnostic management strategy of CCTA alone against CCTA in combination with CTP. METHODS: Patients with acute-onset chest pain older than 50 years and with at least one cardiovascular risk factor for CAD are being prospectively enrolled to this study from 6 different clinical sites since October 2013. A total of 600 patients will be included. Patients are randomized 1:1 to clinical management based on CCTA or on CCTA in combination with CTP, determining the need for further testing with invasive coronary angiography including measurement of the fractional flow reserve in vessels with coronary artery lesions. Patients are scanned with a 320-row multidetector computed tomography scanner. Decisions to revascularize the patients are taken by the invasive cardiologist independently of the study allocation. The primary end point is the frequency of revascularization. Secondary end points of clinical outcome are also recorded. DISCUSSION: The CATCH-2 will determine whether CCTA in combination with CTP is diagnostically superior to CCTA alone in the management of patients with acute-onset chest pain.

The importance of nonobstructive plaque characteristics in symptomatic and asymptomatic coronary artery disease.

BACKGROUND: We examined obstructive and nonobstructive plaque volumes in populations with subclinical and clinically manifested coronary artery disease (CAD) using quantitative computed tomography (QCT). METHODS: 855 participants with CAD (274 asymptomatic individuals, 254 acute chest pain patients without acute coronary syndrome (ACS), and 327 patients with ACS) underwent QCT of proximal coronary segments to assess participant-level plaque volumes of dense calcium, fibrous, fibrofatty, and necrotic core tissue. RESULTS: Nonobstructive (<50% stenosis) plaque volumes were greater than obstructive plaque volumes, irrespective of population (all p<0.0001): Asymptomatic individuals (mean (95% CI)): 218 [190-250] vs. 16 [12-22] mm3; acute chest pain patients without ACS: 300 [263-341] vs. 51 [41-62] mm3; patients with ACS: 370 [332-412] vs. 159 [139-182] mm3. After multivariable adjustment, nonobstructive fibrous and fibrofatty tissue volumes were greater in acute chest pain patients without ACS compared to asymptomatic individuals (fibrous tissue: 122 [107-139] vs. 175 [155-197] mm3, p<0.01; fibrofatty tissue: 44 [38-50] vs. 71 [63-80] mm3, p<0.01. Necrotic core tissue was greater in ACS patients (29 [26-33] mm3) compared to both asymptomatic individuals (15 [13-18] mm3, p<0.0001) and acute chest pain patients without ACS (21 [18-24] mm3, p<0.05). Nonobstructive dense calcium volumes did not differ between the three populations: 29 [24-36], 29 [23-35], and 41 [34-48] mm3, p>0.3 respectively. CONCLUSION: Nonobstructive CAD was the predominant contributor to total atherosclerotic plaque volume in both subclinical and clinically manifested CAD. Nonobstructive fibrous, fibrofatty and necrotic core tissue volumes increased with worsening clinical presentation, while nonobstructive dense calcium tissue volumes did not.

Aortic enlargement and coronary artery calcification in a general population cohort.

AIMS: The role of atherosclerosis in the pathogenesis of aortic enlargement is uncertain. We aimed to evaluate the relationship between the diameters of the ascending, descending and abdominal aorta, and coronary artery calcification. METHODS AND RESULTS: Individuals in the Copenhagen General Population Study underwent thoracic and abdominal computed tomography. Maximal aortic diameters were measured in each aortic segment and coronary artery calcium scores (CACS) were calculated. Participants were stratified into five predefined groups according to CACSs and compared to aortic dimensions. The relation between aortic diameter and CACS was adjusted for risk factors for aortic dilatation in a multivariable model. A total of 2678 eligible individuals were included. In all segments of the aorta, aortic diameter was associated to CACSs, with mean increases in aortic diameters ranging from 0.7 to 3.5 mm in individuals with calcified coronary arteries compared to non-calcified subjects (P-value < 0.001). After correction for risk factors, individuals with CACS above 400 had larger ascending, descending and abdominal aortic diameter than the non-calcified reference group (P-value < 0.01). CONCLUSION: Enlarged thoracic and abdominal aortic vascular segments are associated with co-existing coronary artery calcification in the general population.

Arterial hypertension and morphologic abnormalities of cardiac chambers: results from the Copenhagen General Population Study.

OBJECTIVES: In patients with arterial hypertension (AH), hypertension-mediated organ damage may be manifested by cardiac chamber enlargement and/or remodeling. Cardiac computed tomography imaging has emerged as an important method for morphological assessment of cardiac chambers. We tested the hypothesis that prevalence of cardiac chamber abnormalities is specifically related to clinical categories of AH in the general population. METHODS: We studied 4747 individuals, mean age was 60 years (range: 40-93), 46% were men, undergoing 320-detector computed tomography in the Copenhagen General Population Study. Clinical categories of AH were: normotensive (n = 2484), untreated hypertensive (n = 1301), treated controlled hypertensive (n = 412) and treated uncontrolled hypertensive (n = 550). Chamber abnormalities in the form of left ventricular (LV) concentric remodeling, LV eccentric hypertrophy, LV concentric hypertrophy or left atrial enlargement were assessed, in addition to LV or right ventricular enlargement. RESULTS: Chamber abnormalities were present in 23% of all individuals. Combined LV and left atrial abnormalities were rare (<2%). LV concentric remodeling (10%) was the most prevalent abnormality, and most commonly found in individuals with treated hypertension. LV and right ventricular enlargements were unrelated to hypertension. The highest frequencies of chamber abnormalities were found in individuals of elevated blood pressure (BP) with (40%) or without (32%) treatment, as opposed to individuals of normal BP with (27%) or without (14%) treatment, P less than 0.0001. CONCLUSION: In a general population cohort, untreated or inadequately treated AH was associated with the highest prevalence of cardiac chamber enlargement and remodeling. These observations suggest a strong link between elevated BPs and development of hypertension-mediated organ damage.

Cardiac ventricular sizes are reduced in patients with long-term, normoalbuminuric type 1 diabetes compared to the non-diabetic background population.

AIMS: Type 1 diabetes entails increased cardiovascular morbidity and cardiac chamber sizes are associated with cardiovascular disease. The aim of this study was to compare cardiac chamber sizes in normoalbuminuric persons with type 1 diabetes to a background population without diabetes. METHODS: In a cross-sectional study, we examined 71 normoalbuminuric persons with long-term type 1 diabetes without known cardiovascular disease using cardiac multi-detector computed tomography. Cardiac chamber sizes and left ventricular remodelling were compared to persons without diabetes from the Copenhagen General Population Study. RESULTS: Participants were median (interquartile range) 54 (48-60) (type 1 diabetes) and 57 (50-64) (without diabetes) years old and 59% were men (both groups). Participants with type 1 diabetes had smaller left ventricular mass (-3.5 g/m2, 95% confidence interval -5.8 to -1.3) and left (-4.0 mL/m2, 95% confidence interval -6.9 to -1.0) and right (-11.7 mL/m2, 95% confidence interval -15.4 to -7.9) ventricular volumes in multivariable analyses (adjusted for age, sex, body composition, blood pressure and antihypertensive medication), but no differences in atrial volumes. CONCLUSION: Persons with long-term type 1 diabetes had smaller left ventricular mass and biventricular volumes, yet similar atrial sizes, compared to a background population without diabetes. These findings may reflect subclinical development of diabetic cardiomyopathy.

Value of Myocardial Perfusion Assessment With Coronary Computed Tomography Angiography in Patients With Recent Acute-Onset Chest Pain.

OBJECTIVES: The authors sought to perform a randomized controlled trial to evaluate the clinical efficacy of combined examination with coronary computed tomography angiography (CTA) and computed tomography perfusion imaging (CTP) compared to coronary CTA alone. BACKGROUND: Stress myocardial CTP may increase diagnostic specificity when added to coronary CTA in patients suspected of having ischemic heart disease. METHODS: Patients recently hospitalized for acute-onset chest pain, who had acute coronary syndrome had been ruled out by normal electrocardiograms, normal troponin levels, and relief of symptoms, and who had a clinical indication for outpatient noninvasive testing, were screened for inclusion in the CATCH-2 (CArdiac cT in the treatment of acute CHest pain 2) trial (NCT02014311). Patients were randomized 1:1 to examination with coronary CTA or coronary CTA+CTP. The primary endpoint was the frequency of coronary revascularization among patients referred for invasive coronary angiography (ICA) based on index computed tomography evaluation. Secondary endpoints were invasive procedural complications at index-related ICA, post-index cardiac death, hospital admittance because of recurrence of chest pain, unstable angina pectoris, or acute myocardial infarction, ICA, and revascularization. RESULTS: Among 300 patients allocated to the coronary CTA+CTP group, 41 (14%) were referred for ICA compared with 89 (30%) allocated to coronary CTA (p < 0.0001). The primary endpoint occurred in 50% of coronary CTA+CTP patients versus 48% of invasively examined patients (p = 0.85). The total number of revascularizations was significantly lower in the coronary CTA+CTP group compared to the coronary CTA group (n = 20 [7%] vs. n = 42 [14%]; p = 0.0045). At median follow-up of 1.5 years, the occurrence of secondary endpoints was similar in the 2 groups. CONCLUSIONS: A post-discharge diagnostic strategy of coronary CTA+CTP safely reduces the need for invasive examination and treatment in patients suspected of having ischemic heart disease. (CArdiac cT in the treatment of acute CHest pain 2-Myocardial CT Perfusion [CATCH2]; NCT02014311).

Data on the quantitative assessment pulmonary ground-glass opacification from coronary computed tomography angiography datasets.

We assessed the CT attenuation density of the pulmonary tissue adjacent to the heart in patients with acute non-ST segment elevation myocardial infarction (J.T. Kuhl, T.S. Kristensen, A.F. Thomsen et al., 2016) [1]. This data was related to the level of ground-glass opacification evaluated by a radiologist, and data on the interobserver variability of semi-automated assessment of pulmonary attenuation density was provided.

Assessment of coronary calcification using calibrated mass score with two different multidetector computed tomography scanners in the Copenhagen General Population Study.

OBJECTIVE: Population studies have shown coronary calcium score to improve risk stratification in subjects suspected for cardiovascular disease. The aim of this work was to assess the validity of multidetector computed tomography (MDCT) for measurement of calibrated mass scores (MS) in a phantom study, and to investigate inter-scanner variability for MS and Agaston score (AS) recorded in a population study on two different high-end MDCT scanners. MATERIALS AND METHODS: A calcium phantom was scanned by a first (A) and second (B) generation 320-MDCT. MS was measured for each calcium deposit from repeated measurements in each scanner and compared to known physical phantom mass. Random samples of human subjects from the Copenhagen General Population Study were scanned with scanner A (N=254) and scanner B (N=253) where MS and AS distributions of these two groups were compared. RESULTS: The mean total MS of the phantom was 32.9±0.8mg and 33.1±0.9mg (p=0.43) assessed by scanner A and B respectively - the physical calcium mass was 34.0mg. Correlation between measured MS and physical calcium mass was R2=0.99 in both scanners. In the population study the median total MS was 16.8mg (interquartile range (IQR): 3.5-81.1) and 15.8mg (IQR: 3.8-63.4) in scanner A and B (p=0.88). The corresponding median total AS were 92 (IQR: 23-471) and 89 (IQR: 40-384) (p=0.64). CONCLUSION: Calibrated calcium mass score may be assessed with very high accuracy in a calcium phantom by different generations of 320-MDCT scanners. In population studies, it appears acceptable to pool calcium scores acquired on different 320-MDCT scanners.

Clinical and prognostic correlates of pulmonary congestion in coronary computed tomography angiography data sets.

BACKGROUND: Signs of pulmonary congestion obtained from cardiac computed tomography angiographic (coronary CTA) images have not previously been related to clinical congestion or outcome and the clinical value is, therefore, unknown. Our objective was to test the hypothesis that signs of pulmonary congestion predict clinical heart failure and adverse outcome in patients with myocardial infarction. METHODS: Coronary CTA was performed before invasive treatment in 400 prospectively included patients with non ST segment elevation myocardial infarction in an observational study. Using a previously described chest computed tomography evaluation algorithm, patients were classified as having "no congestion", "mild to moderate congestion" or "severe congestion". RESULTS: Using multivariate analyses, presence of pulmonary congestion on coronary CTA images was associated with age, female gender, left ventricular ejection fraction (LVEF) and left atrial size. The diagnostic accuracy for predicting clinical heart failure, defined as Killip class >1, was: sensitivity: 83%, specificity: 69%, positive predictive value: 25%, and negative predictive value: 97%. The median follow-up time was 50 months and the study end-point of death or hospitalization due to heart failure was reached in 68 (16%) patients. In a Cox proportional hazards model with adjustments for known risk factors and Killip class, the presence of "mild to moderate congestion" and "severe congestion" was independently associated with adverse outcome (Hazard ratio: 2.6 (95% CI:1.3-5.0) and 3.2 (1.3-7.5)). CONCLUSION: Signs of pulmonary congestion on coronary CTA images are closely correlated to cardiac dysfunction, predict clinical heart failure, and provide prognostic value independent of LVEF and Killip class.

Normal values of left ventricular mass and cardiac chamber volumes assessed by 320-detector computed tomography angiography in the Copenhagen General Population Study.

AIMS: Normal values of left ventricular mass (LVM) and cardiac chamber sizes are prerequisites for the diagnosis of individuals with heart disease. LVM and cardiac chamber sizes may be recorded during cardiac computed tomography angiography (CCTA), and thus modality specific normal values are needed. METHODS AND RESULTS: We studied 569 healthy subjects undergoing 320-detector CCTA as a part of the Copenhagen General Population Study. LVM as well as ventricular and atrial volumes was assessed with semi-automated software stratified by gender and age decades and indexed by body surface area (BSA). Mean age was 55 (range: 40-84) years, and 188 (33%) were men. BSA-indexed 97.5th percentile cut-off values: LVM = 80 and 65 gr/m(2), left ventricular volume = 97 and 83 mL/m(2), right ventricular volume = 120 and 102 mL/m(2), left atrial volume = 60 and 57 mL/m(2), and right atrial volume = 85 and 73 mL/m(2) for men and women, respectively. Men had greater absolute and indexed LVM and chamber volumes than women. For both genders, indexed ventricular volumes declined, whereas indexed atrial volumes increased in advancing age groups. For men, indexed LVM declined in advancing age groups. In multivariate analyses, gender, BSA, systolic blood pressure, and hard physical activity accounted for 63% of variance in LVM. CONCLUSION: In this cross-sectional general population study, men have greater indexed LVM and chamber volumes than women, and cardiac indexed volumes vary between age groups in both genders. These findings demonstrate the need for age- and gender-specific normal values for clinical diagnostic purposes.

The Transmural Extent and Severity of Myocardial Hypoperfusion Predicts Long-Term Outcome in NSTEMI: An MDCT Study.

OBJECTIVES: The objective of this study was to test the hypothesis that the extent and severity of left ventricular myocardial hypoperfusion at rest, in addition to signs of left ventricular myocardial scar, are related to adverse long-term outcome in patients with non-ST-segment elevation myocardial infarction (NSTEMI). BACKGROUND: Multidetector computed tomography (MDCT) is a noninvasive test with a spatial resolution that allows for the assessment of transmural myocardial perfusion. In patients with suspected NSTEMI, the assessment of myocardial hypoperfusion could be clinically useful. METHODS: MDCT was performed at rest before invasive treatment in 396 patients with NSTEMI. The transmural involvement of left ventricular hypoperfusion, the presence of intramyocardial fat or calcification, a summed defect score adding the extent of left ventricular myocardial hypoperfusion (0 to 64 point scale), and the transmural attenuation ratio between the subendocardial and the subepicardial myocardium were assessed. The study endpoint was a combination of death and hospitalization due to heart failure. RESULTS: The median follow-up time of the study was 50 months, and the study endpoint was reached in 56 (15%) of the patients. In a Cox proportional hazards survival model with adjustments for known risk factors, both the summed defect score and transmural attenuation ratio were independently associated with adverse outcome (hazard ratio [HR]: 1.07; 95% confidence interval [CI]: 1.02 to 1.11; p = 0.004 and HR: 0.61; 95% CI: 0.44 to 0.85; p = 0.003, respectively). The presence of intramyocardial fat or calcification was also associated with adverse outcome (HR: 3.5; 95% CI: 1.2 to 10.7; p = 0.03) when compared with patients without any perfusion defect. CONCLUSIONS: The extent and severity of left ventricular myocardial hypoperfusion at rest and signs of left ventricular myocardial scar assessed with MDCT before invasive treatment is strongly linked to adverse long-term outcome in patients with NSTEMI.

Feasibility of coronary calcium and stent image subtraction using 320-detector row CT angiography.

BACKGROUND: The reader confidence and diagnostic accuracy of coronary CT angiography (CCTA) can be compromised by the presence of calcified plaques and stents causing blooming artifacts. Compared to conventional invasive coronary angiography (ICA), this may cause an overestimation of stenosis severity leading to false-positive results. In a pilot study, we tested the feasibility of a new coronary calcium image subtraction algorithm in relation to reader confidence and diagnostic accuracy. METHODS: Forty-three patients underwent clinically indicated ICA and CCTA using a 320-detector row CT. Median Agatston score was 510. Two data sets were reconstructed: a conventional CCTA (CCTAconv) and a subtracted CCTA (CCTAsub), where calcifications detected on noncontrast images were subtracted from the CCTA. Reader confidence and concordance with ICA for identification of >50% stenosis were recorded. We defined target segments on CCTAconv as motion-free coronary segments with calcification or stent and low reader confidence. The effect of CCTAsub was assessed. No approval from the ethics committee was required according to Danish law. RESULTS: A total of 76 target segments were identified. The use of coronary calcium image subtraction improved the reader confidence in 66% of these segments. In target segments, specificity (86% vs 65%; P < .01) and positive predictive value (71% vs 51%, P = .03) were improved using CCTAsub compared to CCTAconv without loss in negative predictive value. CONCLUSIONS: Our initial experience with coronary calcium image subtraction suggests that it is feasible and could lead to an improvement in reader confidence and diagnostic accuracy for identification of significant coronary artery disease.

Four-dimensional image processing of myocardial CT perfusion for improved image quality and noise reduction.

BACKGROUND: Image noise and multiple sources of artifact may affect the accurate interpretation of myocardial CT perfusion (CTP) studies. Although artifact within the image is often time dependent, tissue characteristics remain unchanged irrespective of cardiac phase. OBJECTIVE: We assessed a new technique of 4-dimensional, spatiotemporal analysis, using redundant time domain information within additional phase acquisitions to reduce CTP image noise. METHODS: Four-dimensional analysis was assessed in a static phantom and in 10 CTP studies with invasive fractional flow reserve (FFR) correlation. For each voxel within the CTP study the distribution of local Hounsfield values was measured in both time and space with the use of a customized program within MATLAB software. These values were filtered to eliminate those likely to represent noise or rapidly changing beam hardening artifact. All CTP images were acquired within a single heartbeat with 320 detector-row CT. Image noise was quantified as the SD of voxel values within myocardial segments. Contrast was measured between normal and abnormal vascular territories as assessed by FFR. RESULTS: The mean image noise within the unprocessed CTP images was 30 HU (range, 23-42 HU). After 4-dimensional filtering the mean image noise was 22 HU (range, 15-29 HU). The mean reduction in image noise was 28% (P < 0.001). The mean contrast between normally perfused and ischemic segments was not significantly changed. The mean increase in contrast-to-noise ratio between ischemic territories and the myocardial average was 52% (P < 0.001). CONCLUSION: Four-dimensional analysis of CTP significantly reduces image noise and may assist in the assessment of myocardial perfusion studies.

Sex- and age-related differences of myocardial perfusion at rest assessed with multidetector computed tomography.

BACKGROUND: The clinical presentation of ischemic heart disease in women differs from men, which could reflect sex-related differences of normal physiology. Cardiac CT angiography provides a noninvasive method to assess both regional and transmural myocardial perfusion in addition to coronary atherosclerosis. OBJECTIVE: The aim of this study was to evaluate potential sex-related differences of (1) left ventricular (LV) myocardial perfusion measured as LV myocardial attenuation density/LV blood pool attenuation density (MyoAD-ratio) at rest and (2) transmural perfusion ratio (TPR) as a measure of endocardial perfusion relative to epicardial perfusion. METHODS: Myocardial perfusion at rest and coronary artery atherosclerosis were evaluated with multidetector CT in 206 asymptomatic women and 203 age-matched men from the Copenhagen General Population Study. RESULTS: LV myocardial perfusion at rest (LV MyoAD-ratio) was higher in women than in men (9% difference; P = 0.039). In a multivariable analysis, including age, sex, cardiovascular risk factors, Agatston score, and presence of coronary stenosis, global LV MyoAD-ratio remained significantly higher in women than in men (P = 0.045). No effect of cardiovascular risk factors on myocardial perfusion at rest was noted. Myocardial perfusion at rest was correlated to age in men (r = 0.15, P = 0.031) but not in women (r = -0.01, P = 0.83). TPR was slightly lower in women than in men (1.12 vs 1.14; P = 0.0019). CONCLUSION: LV myocardial perfusion at rest is higher in women than men independent of coronary atherosclerosis in asymptomatic subjects with risk factors.

Patterns of myocardial perfusion in humans evaluated with contrast-enhanced 320 multidetector computed tomography.

Left ventricular (LV) myocardial contrast enhancement can be recorded using 320 multi detector computed tomography (MDCT). We aimed to (1) assess patterns of regional myocardial perfusion at rest and compare them with NH(3) positron emission tomography (PET) (2) and to assess the effect of intravenous adenosine infusion on regional myocardial perfusion. To evaluate myocardial perfusion patterns at rest, we scanned 14 healthy subjects with PET and 14 age and gender matched subjects with 320 MDCT. To evaluate the effect of adenosine stress on relative perfusion patterns 14 subjects with near-normal epicardial coronary arteries were studied at rest and during adenosine stress. Relative perfusion was assessed as attenuation density (AD) in 16 segments of the LV, and each segment was divided into 3 layers: endo-, mid- and epi-cardial. During rest the relative AD by MDCT was lower in the lateral wall compared with the remainder of the LV (P < 0.002). A similar pattern was found by PET-imaging. LV endocardial AD was higher than mid- and epicardial AD (P < 0.05). At rest the endocardial/epicardial ratio in the septum was 0.99 compared with 1.23 in non-septal segments (P < 0.001). During adenosine infusion transmural AD increased due to significant increases in the mid- and epicardium and the endocardial/epicardial ratio decreased by 18% in non-septal segments (from 1.23 to 1.05 P < 0.001). Relative perfusion at rest is lower in the lateral wall of the LV with both PET and MDCT compared to the remainder of the myocardium. During adenosine stress endocardial/epicardial ratio decrease significantly.

Assessment of left atrial volume and function: a comparative study between echocardiography, magnetic resonance imaging and multi slice computed tomography.

Measurement of left atrial (LA) maximal volume (LA(max)) using two-dimensional transthoracic echocardiography (TTE) provides prognostic information in several cardiac diseases. However, the relationship between LA(max) and LA function is poorly understood and TTE is less well suited for measuring dynamic LA volume changes. Conversely, cardiac magnetic resonance imaging (CMR) and multi-slice computed tomography (MSCT) appears more appropriate for such measures. We sought to determine the relationship between LA size assessed with TTE and LA size and function assessed with CMR and MSCT. Fifty-four patients were examined 3 months post myocardial infarction with echocardiography, CMR and MSCT. Left atrial volumes and LA reservoir function were assessed by TTE. LA time-volume curves were determined and LA reservoir function (cyclic change and fractional change), passive emptying function (reservoir volume) and pump function (left atrial ejection fraction-LAEF) were derived using CMR and MSCT. Left atrial fractional change and left atrial ejection fraction (LAEF) determined with CMR and MSCT were unrelated to LA(max) enlargement by echocardiography (P = NS). There was an overall good agreement between CMR and MSCT, with a small to moderate bias in LA(max) (4.9 ± 10.4 ml), CC (3.1 ± 9.1 ml) and reservoir volume (3.4 ± 9.1 ml). TTE underestimates LA(max) with up to 32% compared with CMR and MSCT (P < 0.001). Left atrial function assessed with MSCT and CMR as LA fractional change and LAEF is not significantly related to LA(max) measured by TTE. TTE systematically underestimated LA volumes, whereas there are good agreements between MSCT and CMR for volumetric and functional properties.