Coronary Computed Tomography Angiography-Derived Plaque Quantification in Patients With Acute Coronary Syndrome.

This study investigated the discriminatory value of quantitative atherosclerotic plaque markers derived from coronary computed tomography angiography (cCTA) in patients with first acute coronary syndrome (ACS) compared with patients with stable coronary artery disease (CAD). Forty patients (56.9 ± 9.3 years, 55% men) admitted with their first ACS and Framingham risk score-matched controls with stable CAD were retrospectively analyzed. All patients had undergone cCTA followed by invasive coronary angiography. Total plaque volume, calcified and noncalcified plaque volumes, plaque burden (in %), remodeling index, lesion length, presence of napkin-ring sign, segment involvement score, and segment stenosis score were derived from cCTA and compared between both groups on a per-lesion and per-patient level. Patients with ACS showed a significant higher number of obstructive CAD and higher values for segment stenosis score, segment involvement score, noncalcified plaque volume, lesion length, and remodeling index than the stable angina group (all p <0.05). On a per-lesion level, culprit lesions had significantly higher values for plaque burden, total plaque volume, noncalcified plaque volume, remodeling index, lesion length, and prevalence of napkin-ring sign in comparison to nonculprit lesions (all p <0.05). On receiver-operating characteristics (ROC) analysis, a stepwise model demonstrated incremental discriminatory power for identifying ACS both per-patient (area under the curve 0.92, p <0.0001) as well as per-lesion (area under the curve 0.88, p <0.0001). cCTA-derived culprit plaque markers show discriminatory value both on a per-patient and per-lesion level. A combination of markers added to the Framingham risk score yields the greatest discriminatory ability.

Prognostic implications of coronary CT angiography-derived quantitative markers for the prediction of major adverse cardiac events.

OBJECTIVE: To evaluate quantitative markers derived from coronary CT angiography (coronary CTA) for the prediction of major adverse cardiac events (MACE). MATERIALS AND METHODS: Pooled data from two centers in the US and Europe were retrospectively analyzed. Forty-six patients (65.5 ± 8.1 years, 62% male) with suspected coronary artery disease (CAD) who had undergone dual-source CCTA and had experienced MACE within 12 months were included and compared to a Framingham risk score matched cohort (n = 46) without MACE. Various quantitative markers derived from coronary CTA were compared between both groups: Total plaque volume (TPV), calcified and non-calcified plaque volumes (CPV and NCPV), plaque burden (%), remodeling index, lesion length, presence of Napkin-ring sign, segment involvement score (SIS), and segment stenosis score (SSS). Discriminatory power of these markers for predicting MACE was assessed. RESULTS: Patients with MACE had significantly more obstructive CAD with higher plaque burden, SSS, and SIS (all p < 0.05) compared to controls. MACE-related lesions showed higher median TPV (122.6 mm3 vs. 76.3 mm3), NCPV (67.3 mm3 vs. 56.1 mm3), plaque burden (66.3% vs. 44.9%), greater lesion length (23.1 mm vs. 19.2 mm), and higher prevalence of Napkin-ring sign (63% vs. 32%) (all p < 0.05). On multivariable analysis, odds ratios (OR) for MACE on a per-patient level were 1.07 for plaque burden (p = 0.0002) and 1.13 for SSS (p = 0.049). On a per-lesion basis OR for lesion length was 1.05 (p = 0.042), 1.03 for plaque burden (p = 0.018), 1.28 for remodeling index (p = 0.026), and 1.68 for the Napkin-ring sign (p = 0.031). At receiver operating characteristics analysis a combination of markers (Framingham risk score + Napkin-ring sign + lesion length + remodeling index) showed the highest predictive value for MACE (AUC 0.92, p = 0.013). CONCLUSION: Coronary CTA-derived markers portend predictive value for MACE on a per-patient (plaque burden and SSS) and per-lesion level (lesion length, plaque burden, remodeling index, and Napkin-ring sign). A combination of markers added to the Framingham risk score has the highest predictive power.

Coronary CT angiography-derived quantitative markers for predicting in-stent restenosis.

OBJECTIVE: To evaluate quantitative markers derived from coronary CT angiography (coronary CTA) performed prior to percutaneous coronary intervention (PCI) with stent placement for predicting in-stent restenosis (ISR) as defined by quantitative coronary angiography (QCA). MATERIALS AND METHODS: We retrospectively analyzed the data of 74 patients (60 ± 12 years, 72% male) who had undergone dual-source coronary CTA within 3 months prior to a PCI procedure that included stent placement. Quantitative markers of the target vessel were derived from coronary CTA: Total plaque volume (TPV), calcified and non-calcified plaque volumes (CPV and NCPV), plaque burden (PB in %), remodeling index (RI), and lesion length (LL). Marker performance for predicting ISR, as defined by QCA at follow-up, was assessed. RESULTS: Twenty-one of 74 stented lesions showed ISR on follow-up (mean 616 ± 447 days). When comparing stent length and LL in patients with ISR, a trend towards less complete stent coverage of the target lesion was observed in cases with ISR (17/21 vs. 4/53 cases, p = 0.07). In multivariate analysis (corrected for dyslipidemia), the following markers showed predictive value for ISR (odds ratio [OR]): NCPV (OR 1.08, p = 0.045), LL (OR 1.38, p = 0.0024), and RI (OR 1.13, p = 0.0019). Sensitivity and specificity for ISR were: NCPV 65% and 80%, LL 74% and 74%, and RI 71% and 78%. At receiver-operating characteristics analysis, NCPV (0.72, p = 0.001), LL (0.77, p < 0.0001), and RI (0.79, p < 0.0001) showed discriminatory power for predicting ISR. A combination of these markers showed incremental predictive value (AUC 0.89, p < 0.0001) with sensitivity and specificity of 90% and 84%, respectively. CONCLUSION: Coronary CTA-derived NCPV, LL, and RI portend predictive value for ISR with incremental predictive value when combining these parameters.

Imaging coronary artery disease and the myocardial ischemic cascade: clinical principles and scope.

On a subcellular level, atherogenesis is characterized by the translocation of proatherogenic lipoproteins into the arterial wall. An inflammatory response involving complex repair mechanisms subsequently causes maladaptive vascular changes resulting in coronary stenosis or occlusion. The chronology of the underlying processes occurring from atherosclerosis to myocardial ischemia affect the selection and interpretation of diagnostic testing. An understanding of the ischemic cascade, atherosclerosis, coronary remodeling, plaque morphology, and their relationship to clinical syndromes is essential in determining which diagnostic modalities are useful in clinical practice.

Transient Ischemic Dilation of the Left Ventricle on SPECT: Correlation with Findings at Coronary CT Angiography.

UNLABELLED: Transient ischemic dilation (TID) in the setting of abnormal stress-rest cardiac SPECT myocardial perfusion imaging (MPI) has been linked with increased cardiovascular risk. However, the significance of TID in the setting of an otherwise normal SPECT MPI study has not been clearly established. In this study, cardiac CT was used to evaluate the prevalence of atherosclerotic lesions and the severity of coronary artery stenosis in patients with TID of the left ventricle with or without associated myocardial perfusion defects on SPECT MPI. METHODS: The study population consisted of 1,553 consecutive patients who had undergone both cardiac CT and SPECT MPI within 1 mo between January 1, 2006, and September 1, 2011. Patients included in the study group had a pathologic TID value defined as ≥1.18 for men and ≥1.22 for women. Coronary CT angiography was used to evaluate each coronary segment for the presence and composition of atherosclerotic plaque and the degree of coronary stenosis. TID-positive patients were compared with a 2:1 risk-factor-matched-pair control cohort without TID. RESULTS: TID was identified in 30 patients who were compared with TID-negative risk-factor-matched controls (n = 60). When compared with the TID-negative control cohort, TID-positive patients had no significant differences in the presence and extent of atherosclerosis, the degree of coronary artery stenosis, or the calcium score at cardiac CT. Similarly, there were no significant differences in these CT measures in TID-positive patients with a normal perfusion study (n = 20) when compared with TID-negative patients with a normal perfusion study (n = 48). In addition, there was no significant difference in the incidence of major adverse cardiac events when comparing both the TID-positive patients and the TID-negative control cohort and when comparing patients who were TID-positive with normal perfusion with patients who were TID-negative with normal perfusion. CONCLUSION: The presence of TID with an otherwise normal SPECT MPI study does not translate into a greater extent of coronary artery disease as assessed by cardiac CT or increased risk for future major adverse cardiac events.

Cost-effectiveness of substituting dual-energy CT for SPECT in the assessment of myocardial perfusion for the workup of coronary artery disease.

PURPOSE: We compared cost-effectiveness and potential lifetime benefits of using dual-energy computed tomography (DECT) for myocardial perfusion assessment instead of single photon emission computed tomography (SPECT) for the workup of coronary artery disease (CAD). MATERIALS AND METHODS: A decision and simulation model was developed to estimate cost and health effects of using DECT myocardial perfusion imaging instead of SPECT for identifying patients in need of invasive imaging and possible revascularization. The model was based on the performance indices of stress/rest DECT compared with stress/rest SPECT for detecting myocardial perfusion deficits in 50 patients (mean age 61±10 years) with CAD. Stress/rest perfusion and delayed enhancement cardiac MRI served as reference standard. For DECT a reimbursement of US$1700 was assumed but costs of cardiac MRI were not included in the model. All other actual healthcare costs in these patients were derived from MUSC's hospital billing system. RESULTS: Compared with cardiac MRI, DECT (versus SPECT) had 90% (85%) sensitivity and 71% (58%) specificity for identifying patients with obstructive CAD. Compared with the no imaging and no treatment strategy, routine SPECT gained 13.49 quality-adjusted life-years (QALYs) with an incremental cost-effectiveness ratio (ICER) of US$3557 (in 2010) per QALY. In comparison, DECT ICER was lower (US$3.191 per QALY, p=0.0002) and an additional 0.64 QALYs was obtained (total of 14.13 QALYs) if compared with the SPECT strategy as well as the no imaging and no treatment strategy. CONCLUSION: Using DECT as the first-line imaging test for myocardial perfusion for the workup of patients with CAD has the potential to provide gains in QALYs, while lowering costs if compared to routine myocardial perfusion SPECT.

CT detection of myocardial blood volume deficits: dual-energy CT compared with single-energy CT spectra.

BACKGROUND: The performance of dual-energy CT (DECT) for the detection of myocardial blood volume deficits has not systematically been compared with single-energy CT (SCT) spectra. OBJECTIVE: We evaluated the accuracy for detection of myocardial blood volume deficits in DECT and SCT compared with 99m-Tc-Sestamibi-SPECT (single-photon emission CT) during rest and stress. METHODS: 47 patients underwent rest/stress SPECT myocardial perfusion imaging and cardiac DECT on a dual-source CT scanner. The A- and B-tubes were operated with 140 kV and 80 kV/100 kV, respectively. DECT raw data were reconstructed by (1) only using high-energy (140 kV) CT spectra, (2) only using low-energy (80 kV/100 kV) CT spectra, (3) merging data (30% low- and 70% high-energy CT spectra), and (4) DECT-based iodine maps. Two independent, blinded observers analyzed all CT data according to each of the 4 reconstruction strategies for myocardial blood volume deficits. RESULTS: Specificity and positive predictive values were relatively similar between the 4 reconstruction strategies, with highest specificity (98%) of SCT datasets based on 140 kV for mixed perfusion deficits seen on SPECT. DECT iodine maps showed highest sensitivity, negative predictive value, and accuracy of 91%, 97%, and 93%, respectively, for mixed perfusion deficits. Analysis with receiver operating characteristics showed highest area under the curve values (0.84-0.93) with the use of DECT iodine maps in the detection of purely fixed and mixed perfusion deficits. CONCLUSION: DECT iodine maps show superior performance for the detection of fixed and mixed perfusion deficits compared with SCT spectra.

Adenosine-stress dynamic myocardial volume perfusion imaging with second generation dual-source computed tomography: Concepts and first experiences.

Recent research suggests that multidetector-row CT may have potential as a standalone modality for integrative imaging of coronary heart disease, including the assessment of the myocardial blood supply. However, the technical prerequisites for volumetric, time-resolved imaging of the passage of a contrast medium bolus through the myocardium have only been met with latest generation wide-detector CT scanners. Second-generation dual-source CT enables performing electrocardiographic (ECG)-synchronized dynamic myocardial perfusion imaging by a dedicated "shuttle" mode. With this acquisition mode, image data can be acquired during contrast medium infusion at 2 alternating table positions with the table shuttling back and forth between the 2 positions covering a 73-mm anatomic volume. We applied this acquisition technique for detecting differences in perfusion patterns between healthy and diseased myocardium and for quantifying myocardial blood flow under adenosine stress in 3 patients with coronary heart disease. According to our initial experience, the addition of adenosine stress volumetric dynamic CT perfusion to a cardiac CT protocol comprising coronary artery calcium quantification, prospectively ECG-triggered coronary CT angiography, and delayed acquisition appears promising for the comprehensive assessment of coronary artery luminal integrity, cardiac function, perfusion, and viability with a single modality.

Comparison of dual-energy computed tomography of the heart with single photon emission computed tomography for assessment of coronary artery stenosis and of the myocardial blood supply.

To evaluate the performance of dual-energy computed tomography (CT) for integrative imaging of the coronary artery morphology and the myocardial blood supply, 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by a single-contrast medium-enhanced, retrospectively electrocardiographic-gated dual-energy CT (DECT) scan with simultaneous acquisition of high and low x-ray spectra. Thirteen patients subsequently underwent invasive coronary angiography (ICA). The DECT data were used to reconstruct anatomic coronary CT angiographic images and to map the myocardial iodine distribution within the left ventricular myocardium. Two independent observers analyzed all DECT studies for stenosis and myocardial iodine defects. A segmental comparison was performed between the stress/rest SPECT perfusion defects and DECT iodine defects and between the ICA and coronary CT angiographic findings for stenosis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were estimated, along with the kappa statistics. Overall, DECT had 92% sensitivity and 93% specificity, with 93% accuracy for detecting any type of myocardial perfusion defect seen on SPECT. Contrast defects at DECT correctly identified 85 (96%) of 89 fixed and 60 (88%) of 68 reversible myocardial perfusion defects. The interobserver agreement was very good (weighted kappa = 0.87). Compared with ICA, coronary CT angiography had 90% sensitivity, 94% specificity, and 93% accuracy for the detection of >50% stenosis. In conclusion, our initial experience suggests that DECT, as a single examination, might be promising for the integrative analysis of the coronary artery morphology and the myocardial blood supply and is in good agreement with ICA and SPECT.

Noncalcified atherosclerotic plaque burden at coronary CT angiography: a better predictor of ischemia at stress myocardial perfusion imaging than calcium score and stenosis severity.

OBJECTIVE: The purpose of this study was to examine the relation between the coronary CT angiographic findings of calcified and noncalcified plaque burden and stenosis severity and the myocardial perfusion imaging finding of ischemia. MATERIALS AND METHODS: Seventy-two patients (41 men, 31 women; mean age, 56 years) underwent coronary CT angiography and stress-rest SPECT myocardial perfusion imaging. Calcium scoring was performed. Coronary CT angiograms were analyzed for stenosis and noncalcified or mixed plaque. A plaque analysis tool was used to calculate the volume of noncalcified plaque components. SPECT images were analyzed for perfusion defects. Data were analyzed per patient and per vessel. RESULTS: A total of 53 purely noncalcified, 50 mixed, and 201 purely calcified plaques were detected. Forty-five stenoses were rated > or = 50%, 19 of those being > or = 70%. Myocardial perfusion imaging depicted perfusion defects in 37 vessels (13%) in 24 patients (18 reversible, 19 fixed defects). Vessels with > or = 50% stenosis had significantly (p = 0.0009) more perfusion defects in their supplied territories (11 with, 22 without perfusion defects) than did vessels without significant lesions (26 with, 229 without perfusion defects). In vessel-based analysis, the sensitivity of coronary CT angiography in prediction of any perfusion defect on myocardial perfusion images was 30% with 91% specificity, 33% positive predictive value, and 90% negative predictive value. Between vessels with and those without perfusion defects, there was no significant difference in Agatston or calcium volume score (p = 0.25), but there was a significant difference in noncalcified plaque volume (44 +/- 77 vs 19 +/- 58 mm(3); p = 0.03). Multiple stepwise regression analysis showed noncalcified plaque volume was the only significant predictor of ischemia (p = 0.01). CONCLUSION: At coronary CT angiography, noncalcified plaque burden is a better predictor of the finding of myocardial ischemia at stress myocardial perfusion imaging than are calcium score and degree of stenosis.

Dual-energy CT of the heart--principles and protocols.

The introduction of coronary CT angiography (cCTA) has reinvigorated the debate whether management of patients with suspected coronary artery disease (CAD) should be primarily based on physiological versus anatomical testing. Anatomical testing (i.e., cCTA or invasive catheterization) enables direct visualization and grading of coronary artery stenoses but has shortcomings for gauging the hemodynamic significance of lesions for myocardial perfusion. Conversely, rest/stress myocardial perfusion imaging (MPI) has been extensively validated for assessing the clinical significance of CAD by demonstrating fixed or reversible perfusion defects but has only limited anatomical information. There is early evidence that contrast medium enhanced dual-energy cCTA (DECT) has potential for the comprehensive analysis of coronary artery morphology as well as changes in myocardial perfusion. DECT exploits the fact that tissues in the human body and iodine-based contrast media have unique absorption characteristics when penetrated with different X-ray energy levels, which enables mapping the iodine (and thus blood) distribution within the myocardium. The purpose of this communication is to describe the practical application of this emerging technology for the comprehensive diagnosis of coronary artery disease in the context of the currently used tomographic imaging modalities (cCTA, nuclear MPI, MR MPI).

Quantitative assessment of pericardial effusion volume by two-dimensional echocardiography.

The clinical applicability of a method for quantifying pericardial effusion (PE) was studied. The pericardial and cardiac volumes were determined from border tracings of 2-dimensional echocardiograms fitted with 3-dimensional disk models. The PE volume was the difference between pericardial and cardiac volumes. A phantom study included 54 cases with different volumes and viewing geometry showed a correlation coefficient r = 0.98 and an accuracy of +/- 6%. A clinical study included 20 cases showing that the estimated PE volume correlated well with that drained surgically (between 100 mL and 1200 mL): y = 0.81 x + 120 mL; r = 0.91, P <.0001. The percent error, determined by the standard error of the estimate (114 mL) over mean (548 mL), was 20%. Intraobserver variability was 4% and interobserver variability 6%. The 3-dimensional disk method provides a quick and convenient way to quantify PE from 2-dimensional echocardiograms with acceptable accuracy and reproducibility.