Trabecular bone mineral density as measured by thoracic vertebrae predicts incident hip and vertebral fractures: the multi-ethnic study of atherosclerosis.

We evaluated the relationship of bone mineral density (BMD) by computed tomography (CT), to predict fractures in a multi-ethnic population. We demonstrated that vertebral and hip fractures were more likely in those patients with low BMD. This is one of the first studies to demonstrate that CT BMD derived from thoracic vertebrae can predict future hip and vertebral fractures. PURPOSE/INTRODUCTION: Osteoporosis affects an enormous number of patients, of all races and both sexes, and its prevalence increases as the population ages. Few studies have evaluated the association between the vertebral trabecular bone mineral density(vBMD) and osteoporosis-related hip fracture in a multiethnic population, and no studies have demonstrated the predictive value of vBMD for fractures. METHOD: We sought to determine the predictive value of QCT-based trabecular vBMD of thoracic vertebrae derived from coronary artery calcium scan for hip fractures in the Multi-Ethnic Study of Atherosclerosis(MESA), a nationwide multicenter cohort included 6814 people from six medical centers across the USA and assess if low bone density by QCT can predict future fractures. Measures were done using trabecular bone measures, adjusted for individual patients, from three consecutive thoracic vertebrae (BDI Inc, Manhattan Beach CA, USA) from non-contrast cardiac CT scans. RESULTS: Six thousand eight hundred fourteen MESA baseline participants were included with a mean age of 62.2 ± 10.2 years, and 52.8% were women. The mean thoracic BMD is 162.6 ± 46.8 mg/cm3 (95% CI 161.5, 163.7), and 27.6% of participants (n = 1883) had osteoporosis (T-score 2.5 or lower). Over a median follow-up of 17.4 years, Caucasians have a higher rate of vertebral fractures (6.9%), followed by Blacks (4.4%), Hispanics (3.7%), and Chinese (3.0%). Hip fracture patients had a lower baseline vBMD as measured by QCT than the non-hip fracture group by 13.6 mg/cm3 [P < 0.001]. The same pattern was seen in the vertebral fracture population, where the mean BMD was substantially lower 18.3 mg/cm3 [P < 0.001] than in the non-vertebral fracture population. Notably, the above substantial relationship was unaffected by age, gender, race, BMI, hypertension, current smoking, medication use, or activity. Patients with low trabecular BMD of thoracic vertebrae showed a 1.57-fold greater risk of first hip fracture (HR 1.57, 95% CI 1.38-1.95) and a nearly threefold increased risk of first vertebral fracture (HR 2.93, 95% CI 1.87-4.59) compared to normal BMD patients. CONCLUSION: There is significant correlation between thoracic trabecular BMD and the incidence of future hip and vertebral fracture. This study demonstrates that thoracic vertebrae BMD, as measured on cardiac CT (QCT), can predict both hip and vertebral fractures without additional radiation, scanning, or patient burden. Osteopenia and osteoporosis are markedly underdiagnosed. Finding occult disease affords the opportunity to treat the millions of people undergoing CT scans every year for other indications.

Opportunistic AI-enabled automated bone mineral density measurements in lung cancer screening and coronary calcium scoring CT scans are equivalent.

Rationale and objectives: We previously reported a novel manual method for measuring bone mineral density (BMD) in coronary artery calcium (CAC) scans and validated our method against Dual X-Ray Absorptiometry (DEXA). Furthermore, we have developed and validated an artificial intelligence (AI) based automated BMD (AutoBMD) measurement as an opportunistic add-on to CAC scans that recently received FDA approval. In this report, we present evidence of equivalency between AutoBMD measurements in cardiac vs lung CT scans. Materials and methods: AI models were trained using 132 cases with 7649 (3 mm) slices for CAC, and 37 cases with 21918 (0.5 mm) slices for lung scans. To validate AutoBMD against manual measurements, we used 6776 cases of BMD measured manually on CAC scans in the Multi-Ethnic Study of Atherosclerosis (MESA). We then used 165 additional cases from Harbor UCLA Lundquist Institute to compare AutoBMD in patients who underwent both cardiac and lung scans on the same day. Results: Mean±SD for age was 69 ± 9.4 years with 52.4% male. AutoBMD in lung and cardiac scans, and manual BMD in cardiac scans were 153.7 ± 43.9, 155.1 ± 44.4, and 163.6 ± 45.3 g/cm3, respectively (p = 0.09). Bland-Altman agreement analysis between AutoBMD lung and cardiac scans resulted in 1.37 g/cm3 mean differences. Pearson correlation coefficient between lung and cardiac AutoBMD was R2 = 0.95 (p < 0.0001). Conclusion: Opportunistic BMD measurement using AutoBMD in CAC and lung cancer screening scans is promising and yields similar results. No extra radiation plus the high prevalence of asymptomatic osteoporosis makes AutoBMD an ideal screening tool for osteopenia and osteoporosis in CT scans done for other reasons.

Use of Advanced CT Technology to Evaluate Left Atrial Indices in Patients with a High Heart Rate or with Heart Rate Variability: The Converge Registry.

We intended to assess the ability of current-generation 256-slice coronary CT angiography (CCTA) to measure left atrial volume (LAV), comparing patients with a high heart rate (HiHR) of at least 70 bpm and patients with heart rate variability such as atrial fibrillation (AFib). Methods: Using the prospective Converge Registry of patients undergoing 256-detector CCTA on a Revolution scanner, we enrolled 121 HiHR patients (74 men; mean age, 62.7 ± 12.5 y) and 102 AFib patients (72 men; mean age, 60.5 ± 11.0 y) after obtaining informed consent. Quantitative data analysis of LAV was performed using automated methods, and end-systolic phases were chosen for measurements from CCTA. A Student t test, Wilcoxon rank-sum test, or χ2 test assessed baseline parameters. Univariate and multivariate linear regression analysis was used to assess LAV and LAV index (LAVI) while adjusting potentially confounding variables. Results: Mean LAV was significantly higher in AFib subjects (148.6 ± 57.2 mL) than in HiHR subjects (102.1 ± 36.5 mL) (P < 0.0001). Similarly, mean LAVI was significantly higher in AFib subjects (72.4 ± 28.1 mL/m2) than in HiHR subjects (51.5 ± 19.0 mL/m2) (P < 0.0001). After adjusting for age, body mass index, sex, diabetes, hypertension, hyperlipidemia, and smoking, subjects with AFib had, on average, LAV measures higher by 41.2 ± 6.7 mL and LAVI values higher by 23.1 ± 3.4 mL/m2 (P < 0.0001). Conclusion: Misalignment and motion artifacts in CCTA images affect diagnostic CT performance, especially in patients with elevated heart rates or profound arrhythmia. However, the new-generation Revolution CCTA provides detailed information on left-atrium-complex morphology and function, in addition to coronary anatomy, in HiHR and AFib patients without additional radiation, scanning, or contrast requirements.

Aged garlic extract reduces left ventricular myocardial mass in patients with diabetes: A prospective randomized controlled double-blind study.

Increased left ventricular myocardial mass (LVM) is a well known prognostic marker of poor cardiac outcomes. Decreases in LVM have been shown to decrease the cardiovascular risk. Aged garlic extract (AGE) has been shown to have an overall favorable effect on cardiac health; however, to the best of our knowledge, no study to date has specifically examined its effects on left ventricular mass. This study investigated whether AGE can affect LVM measured by cardiac computed tomography angiography (CCTA) in patients with diabetes mellitus (DM). This is a double-blind, placebo controlled randomized trial. In total, 65 participants with DM with a mean age of 58 years were prospectively assigned to consume 2,400 mg AGE/day or the placebo orally. Both groups underwent CCTA at baseline and follow-up at 1 year apart. LVM was measured using automated software. The baseline characteristics did not differ between the AGE and placebo groups. There was a trend towards a significant reduction in LVM at follow-up as compared to baseline in the AGE group (119.30±34.77 vs. 121.0±34.70, P=0.059). No change was observed in LVM in the placebo group at 1-year follow-up as compared to baseline (124.6±37.33 vs. 124.6±35.13, P=0.9). On the whole, this study indicated that AGE may decrease or stabilize LVM. Further studies however, with a larger sample size and longer follow-up times are required to evaluate the effects of AGE on hypertension and LVM.

Identifying Smoking-Related Disease on Lung Cancer Screening CT Scans: Increasing the Value.

BACKGROUND: Lung cancer screening (LCS) via chest computed tomography (CT) scans can save lives by identifying early-stage tumors. However, most smokers die of comorbid smoking-related diseases. LCS scans contain information about smoking-related conditions that is not currently systematically assessed. Identifying these common comorbid diseases on CT could increase the value of screening with minimal impact on LCS programs. We determined the prevalence of 3 comorbid diseases from LCS eligible scans and quantified related adverse outcomes. METHODS: We studied COPD Genetic Epidemiology study (COPDGene®) participants (n=4078) who met criteria for LCS screening at enrollment (age > 55 years, and < 80 years, > 30 pack years smoking, current smoker or former smoker within 15 years of smoking cessation). CT scans were assessed for coronary artery calcification (CAC), emphysema, and vertebral bone density. We tracked the following clinically significant events: myocardial infarctions (MIs), strokes, pneumonia, respiratory exacerbations, and hip and vertebral fractures. RESULTS: Overall, 77% of eligible CT scans had one or more of these diagnoses identified. CAC (> 100 mg) was identified in 51% of scans, emphysema in 44%, and osteoporosis in 54%. Adverse events related to the underlying smoking-related diseases were common, with 50% of participants reporting at least one. New diagnoses of cardiovascular disease, emphysema and osteoporosis were made in 25%, 7% and 46%, of participants respectively. New diagnosis of disease was associated with significantly more adverse events than in participants who did not have CT diagnoses for both osteoporosis and cardiovascular risk. CONCLUSIONS: Expanded analysis of LCS CT scans identified individuals with evidence of previously undiagnosed cardiovascular disease, emphysema or osteoporosis that corresponded with adverse events. LCS CT scans can potentially facilitate diagnoses of these smoking-related diseases and provide an opportunity for treatment or prevention.

Thoracic Quantitative Computed Tomography (QCT) Can Sensitively Monitor Bone Mineral Metabolism: Comparison of Thoracic QCT vs Lumbar QCT and Dual-energy X-ray Absorptiometry in Detection of Age-relative Change in Bone Mineral Density.

RATIONALE AND OBJECTIVE: Sensitive detection of bone mineral density (BMD) change is a key issue to monitor and evaluate the individual bone health status, as well as bone metabolism and bone mineral status. The ability to use thoracic quantitative computed tomography (QCT) to detect the annual change of BMD remains unclear. We aimed to investigate the sensitivity in detecting age-related bone mineral loss using the thoracic QCT from the electrocardiographically gated heart scans in comparison to whole-body dual-energy X-ray absorptiometry (DXA) and standard lumbar QCT. MATERIALS AND METHODS: A total of 121 asymptomatic patients' imaging data, including DXA whole body scan, cardiac CT scan, and abdomen scans were analyzed. The BMD of the thoracolumbar spine, upper, and lower extremities were measured using QCT and DXA, respectively. The age-related annual rate of bone density loss was computed and compared to the thoracic and lumbar QCT, as well DXA measures. RESULTS: The age-related annual rate of bone loss with QCT was -0.70 mg/mL3 (-0.75%/y) in women, -0.83 mg/mL3 (-0.86%/y) in men in the thoracic and the lumbar trabecular QCT, respectively. Compared to the QCT, DXA demonstrates a lower annual rate of bone loss in the area of BMD measurement (P < .05 in all, excluding legs of women) in -0.45, -0.42, -0.67, and -0.46 in women, in -0.32, -0.02, -0.12, and -0.08 in men for thoracic, lumbar, leg, and arm, respectively. CONCLUSION: We conclude that the thoracic and the lumbar QCT provide a similar and more sensitive method for detecting bone mineral loss when compared to DXA.

Routine Coronary Calcium Scan Can Precisely Measure Vertebral Bone Density Without a Quantitative Calibration Phantom.

OBJECTIVE: We aimed to assess accuracy and precision of quantitative computed tomography (QCT) and phantomless in thoracic bone mineral density (BMD) assessment using coronary artery calcium scan (CACS). METHODS: A total of 513 subjects underwent CACS with a calibration phantom. The thoracic spine BMD and concentration of calcium hydroxyapatite in phantom rods, as well CT Hounsfield unit of both, were measured. The thoracic BMD and phantom-rods calcium concentration were obtained using phantomless. The accuracy and precision error of QCT and phantomless were compared. RESULTS: The mean biases from true calcium concentration of phantom rods were 2.9% and 3.8% for the QCT and phantomless, respectively (P < 0.001). The biases of thoracic BMD from QCT by phantomless were 3.8% with a similar precision error in both methods. CONCLUSIONS: The thoracic BMD can be assessed accurately and precisely using QCT and phantomless with a routine CACS.

Application of quantitative computed tomography for assessment of trabecular bone mineral density, microarchitecture and mechanical property.

Osteoporosis is a common metabolic bone disease, causing increased skeletal fragility characterized by a low bone mass and trabecular microarchitectural deterioration. Assessment of the bone mineral density (BMD) is the primary determinant of skeletal fragility. Computed tomography (CT)-based trabecular microarchitectural and mechanical assessments are important methods to evaluate the skeletal strength. In this review, we focus the feasibility of QCT BMD measurement using a calibration phantom or phantomless. The application of QCT could extend the bone mineral density assessment to all patients who underwent a heart, lung, whole-body, and as well as all routine clinical implications of CT scan.

[Preliminary reports of noninvasive accurate method to measure pulmonary vascular capacity in normal volunteers].

OBJECTIVE: Because the traditional loop of breathing control and regulation effect on blood circulation, there was rare study of pulmonary vein capacity. We need a noninvasive and accurate pulmonary vascular capacity measurement and analysis method. METHODS: Twelve normal volunteers were performed a total lung CT scan, image data analysis processing by computer software, the whole lungs from the apex to the base of lung with 40-50 layers by hand-cut, the connection between adjacent layers automatically by a computer simulation, the full pulmonary vascular (≥ 0.6 mm) were treated by high-accuracy three-dimensional imaging technology after removing the interference, and then calculate the whole lung and pulmonary vascular. RESULTS: The whole lung of the 12 normal volunteers from the apex to the base of lung CT scan image layers was 530 ± 98 (range, 431-841). The total capacity of lung and pulmonary vascular blood was 3705 ± 857 (range, 2398-5383) ml, and the total volume of the pulmonary vascular blood was 125 ± 32 (range, 94-201) ml. The pulmonary vein vascular blood volume was 63 ± 16 (range, 47-100) ml. CONCLUSION: The method of measuring the three-dimensional imaging of pulmonary vascular capacity by analyzing lung CT scan data is available and accurate.

[Normal reference values and predict equations of heart function].

OBJECTIVE: For heart functional parameters, we commonly used normal range. The reference values and predict formulas of heart functional parameters and their relationships with individual characteristics are still lack. METHODS: Left ventricular (LV) volumes (end-diastolic volume and end-systolic volume), stroke volume (SV), ejection fraction (EF) and cardiac output (CO) were measured by cardiac CT angiography (CAT) in 1 200 healthy Caucasian volunteers, men 807 and women 393, and age 20-90yr. The results are analyzed by high-accuracy three-dimensional imaging technology, and then measured the dynamic changes of the volumes of each atriam and ventricule during their contractions and relaxations. The gender, age, height and weight were analyzed by multiple linear regression to predict LV functional parameters. RESULTS: Except the LVEF was lower in man than in women (P < 0.001), all other LV functional parameters of EDV, ESV, SV, FE and CO were higher in man (P < 0.001). Multiple linear regression indicated that age, gender, height and weight are all independent factors of EDV, ESV and SV (P < 0.001). CO could be significantly predicted by age, gender and weight (P < 0.001), but not height (P > 0.05). The predict equation for CO (L x min(-1)) = 6.963+0.446 (Male) -0.037 x age (yr) +0.013 x weight (kg). CONCLUSION: Age, gender, height and weight are predictors of heart functions. The reference values and predict equations are important for noninvasive and accurate evaluation of cardiovascular disease and individualized treatment.

[The correlation of the stroke volume with pulmonary venous volume and left atrial volume].

OBJECTIVE: The same person's pulmonary venous blood volume, left atrial volume and stroke volume were measured by lung CT scans and cardiac CT angiography (CTA). Then their relationships were analyzed in order to investigate the mechanism of breathing control. METHODS: As we described before, full pulmonary vascular (-0.6mm) volume was accurately calculated by three-dimensional imaging technology from lung CT scan; left atrial volume and stroke volume of left ventricle were calculated from the CTA data. Then the relationships among them were analyzed for estimation of the lung-artery time. RESULTS: The total volume of lung and pulmonary vascular blood was 3486 ± 783 (2156-4418) ml, and the pulmonary vascular blood volume was 141 ± 20 (105-163) ml. The estimated pulmonary venous volume was 71 ± 10 (52-81) ml. Left atrial volume at the end diastolic was 97 ± 39 (53-165) ml, Stroke volume of left ventricle was 86 ± 16 (60-106) ml. Pulmonary venous volume and the left atrial volume were double of stroke volume(1.7-2.4). CONCLUSION: The estimated lung-artery time was three heart beat.

Gender differences in coronary artery diameter are not related to body habitus or left ventricular mass.

BACKGROUND: Smaller coronary artery diameter portends worse outcomes after coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI). The suggestion that women have smaller coronary artery diameters than men has not been validated by a large-scale study. HYPOTHESIS: We sought to confirm a gender difference with respect to coronary artery diameter, even after accounting for body habitus and left ventricular mass (LVM). METHODS: From 4200 subjects evaluated for cardiovascular disease by computed tomography angiography, we selected 710 subjects (383 males, 327 females) with coronary artery calcium (CAC) scores <100, eliminating patients with artery remodeling. Diameters of the left main (LM), left anterior descending (LAD), left circumflex (CX), and right coronary arteries (RCA), were measured. Measurements were compared using a 2-sample t test and the multiple regression model, accounting for body habitus and LVM. RESULTS: After adjusting for age, race, weight, height, body mass index, body surface index, LVM, and CAC, women have smaller diameters in the LM (males 4.35 mm, females 3.91 mm), LAD (males 3.54 mm, females 3.24 mm), CX (males 3.18, females 2.75 mm), and RCA (males 3.70 mm, females 3.26 mm) (P < 0.001). This difference is not related to body habitus or LVM. CONCLUSIONS: Gender significantly influences artery diameter of the LM, LAD, CX, and RCA. This may warrant gender specific approaches during PCI and CABG. As neither body habitus nor LVM relate to the difference in coronary artery diameter, our study encourages a search for inherent differences between genders that can account for this difference.

Model-based automatic segmentation algorithm accurately assesses the whole cardiac volumetric parameters in patients with cardiac CT angiography: a validation study for evaluating the accuracy of the workstation software and establishing the reference values.

RATIONALE AND OBJECTIVES: The cardiac chamber volumes and functions can be assessed manually and automatically using the current computed tomography (CT) workstation system. We aimed to evaluate the accuracy and precision and to establish the reference values for both segmentation methods using cardiac CT angiography (CTA). MATERIALS AND METHODS: A total of 134 subjects (mean age 55.3 years, 72 women) without heart disease were enrolled in the study. The cardiac four-chamber volumes, left ventricular (LV) mass, and biventricular functions were measured with manual, semiautomatic, and model-based fully automatic approaches. The accuracies of the semiautomated and fully automated approaches were validated by comparing them with manual segmentation as a reference. The precision error was determined and compared for both manual and automatic measurements. RESULTS: No significant difference was found between the manual and semiautomatic assessments for the assessment of all functional parameters (P > .05). Using the manual method as a reference, the automatic approach provided a similar value in LV ejection fraction and left atrial volumes in both genders and right ventricular (RV) stroke volume in women (P > .05), with some underestimation of RV volume (P < .001) and overestimation of all remaining parameters (P < .05) in both genders. In addition, a significantly higher precision with a considerable association in intermeasurement (reproducibility) was observed using the automated approach. CONCLUSIONS: The model-based fully automatic segmentation algorithm can help with the assessment of the cardiac four-chamber volume and function. This may help in establishing reference values of functional parameters in patients who undergo cardiac CTA.

Dual-standard reference values of left ventricular volumetric parameters by multidetector CT angiography.

BACKGROUND: The papillary and trabecular muscles constitute a significant percentage of left ventricular mass and volume. The influence of the papillary and trabecular muscles on left ventricular parameters has not been described with multidetector CT angiography. OBJECTIVE: The aims of this study are (1) to derive reference values for left ventricular volumetric parameters both including and excluding the papillary and trabecular muscles and (2) to establish the optimal segmentation method for measuring these values. METHODS: A total of 179 subjects (mean age, 55.4 ± 9 years; 102 women) without heart disease and at low risk of cardiovascular disease who underwent CT angiography were selected. Left ventricular volumes, myocardial volume, and ejection fraction were measured with epicardial and 2 endocardial trace methods, including and excluding trace for the papillary and trabecular muscles. Values of all parameters obtained by both endocardial trace methods were compared. RESULTS: Significant difference between both trace groups for all parameters on both sexes was found (P < .001). Significant differences in precision error of remeasurement were found in the including trace (3.6%) compared with the excluding trace (4.7%; P < .05) and in the epicardial trace (2.2%) compared with both endocardial traces (P < .001). CONCLUSION: The left ventricular parameters measured by CT angiography were influenced significantly by the trace method by including or excluding the papillary and trabecular muscles. The dual-standard reference values of left ventricular parameters were established, and the optimal segmentation methods were definite in considering the heart size and image quality studied with retrospective and prospective CT angiography.

Noncontrast cardiac computed tomography image-based vertebral bone mineral density: the Multi-Ethnic Study of Atherosclerosis (MESA).

RATIONALE AND OBJECTIVES: Cardiac computer tomography (CT) image-based vertebral bone mineral density (BMD) assessment and the influence of cardiovascular disease risk factors on BMD have not been systematically evaluated, especially in a community-based, multiethnic population. METHODS: A cross-sectional study design is used to determine if cardiac CT image is a reliable source to assess vertebral BMD, and a total of 2028 CT images were obtained from the Multi-Ethnic Study of Atherosclerosis, a large, diverse US cohort of adults 45 to 84 years of age. RESULTS: Cardiac CT image allows the rapid assessment of vertebral BMD and related fractures. The mean BMD was significantly higher in men compared with women for thoracic vertebrae (143.2 ± 41.2 vs 138.7 ± 42.7 mg/cm³, respectively, P = .014), as well as for lumbar vertebrae (125.0 ± 37.9 vs 117.2 ± 39.4 mg/cm³, respectively, P < .0001). Thoracic and lumbar BMDs are closely correlated (correlation coefficient 0.87, P < .001), independent of age and other confounders including sex and race. African American men had the highest thoracic BMD among all race/ethnicity and sex subgroups. Prevalence of fractures in total vertebrae is 4.2%. Lumbar had approximately 2 times higher prevalence of fracture than thoracic, and the prevalence of vertebral fractures is 1.5% and 3.1% for thoracic and lumbar vertebrae, respectively. CONCLUSIONS: Using cardiac CT images to garner and assess vertebral BMD is a feasible and reliable method. Cardiac CT has the additional advantages of evaluate vertebral bone health while assessing cardiovascular disease risk with no extra cost or radiation exposure.

Detection and quantification of myocardial perfusion defects by resting single-phase 64-slice cardiac computed tomography angiography compared with SPECT myocardial perfusion imaging.

OBJECTIVE: Hypoenhanced regions on cardiac computed tomography angiography (CCTA) correlate with myocardial hypoperfusion. We evaluated the ability of resting single-phase 64-slice CCTA to detect the presence of myocardial infarction (MI) compared with nuclear myocardial perfusion imaging (MPI). METHODS: One hundred and forty symptomatic patients (age 66±12 years, 64% men) with an irreversible perfusion defect (n=69) or a normal/reversible perfusion defect (n=71) on MPI were subjected to CCTA for further evaluation. MI on CCTA was detected visually on the basis of areas of hypoattenuation (dark) in the myocardium and the corresponding Hounsfield Units (HU) were measured. RESULTS: CCTA accurately detected MI in 62 patients with an irreversible perfusion defect on MPI, yielding a sensitivity of 90%, a specificity of 94%, a negative predictive value of 91%, and a positive predictive value of 94%. The mean HU of normal and infarcted left ventricular myocardium was 107±23 and 16±40, respectively (P<0.001). An HU cut-off of 28 detected the presence of myocardial scar with 86% sensitivity and 59% specificity. The infarct volume measured by CCTA correlated well with the summed rest score (r=0.567; P<0.001) and the summed stress score (r=0.489; P<0.001) on MPI. In a substudy of 50 patients, the GE perfusion tool yielded a sensitivity of 92%, a specificity of 73%, an negative predictive value of 91%, and a positive predictive value of 76% in detecting MI. CONCLUSION: Resting single-phase CCTA is highly accurate in detecting and quantifying MI. This study highlights a novel clinical utility of CCTA in addition to assessment of plaque burden and stenosis with no risk of additional radiation or contrast exposure to the patient.

Measurement of phantomless thoracic bone mineral density on coronary artery calcium CT scans acquired with various CT scanner models.

PURPOSE: To determine the accuracy and precision of thoracic phantomless bone mineral density (BMD) measurements obtained on coronary artery calcium (CAC) computed tomography (CT) scans by using a variety of commercially available CT scanners. MATERIALS AND METHODS: The institutional review board approved this Health Insurance Portability and Accountability Act-compliant study. A total of 4126 asymptomatic subjects (2022 [49%] men, 2104 [51%] women; mean age, 63.7 years ± 11.8 [standard deviation]) underwent CAC CT with the use of a quantitative CT calibration phantom for evaluation of subclinical atherosclerosis. Two hundred eighty subjects also underwent CT of the chest, abdomen, and pelvis (C7 through L5). Mean BMD of three consecutive thoracic vertebrae (in the T7-T10 range) was measured in all 4126 subjects. Individual calibration factors for each phantom insert and a general calibration factor for the spine were determined for each CT scanner model. The study population was then divided into three subgroups: All calibration factors were generated from group 1 (n = 1536) and were applied and tested in group 2 (n = 1587), and effects of various image acquisition parameters were assessed in group 3 (n = 1003). Accuracy (bias) and precision of thoracic phantomless BMD measurements across 14 CT scanner models from five manufacturers were determined. RESULTS: Phantomless BMD values correlated highly with standard phantom-based quantitative CT BMD values (r = 0.987, P < .001). Bias was 3.9% ± 1.4 for phantomless BMD measurements, and the mean coefficient of variation for the general calibration factor was 4.9% ± 2.4. CONCLUSION: Phantomless BMD can be measured accurately on CAC CT scans acquired with a variety of CT scanners without additional radiation exposure.

Computerized left ventricular regional ejection fraction analysis for detection of ischemic coronary artery disease with multidetector CT angiography.

Regional ejection fraction (REF) provides important functional information of the left ventricular regional myocardium. We aimed to test the diagnostic accuracy of computerized REF analysis for detecting the ischemia and significant stenosis with multidetector CT angiography (MDCT). This is a retrospective study including 155 patients who underwent MDCT scans for evaluation of coronary artery disease. Among them, 83 patients also underwent SPECT imaging and invasive coronary angiography (ICA). Two groups of patients were defined: Control group with 0 coronary artery calcium and normal global and regional ventricular function, and comparison group. REF measurement was performed on all patients using computerized software. Control group REF measurements will be used as reference standard (mean-2SD REF/mean global ejection fraction) to define abnormal REF. The sensitivity, specificity, positive and negative predictive value of REF in detecting perfusion defects (fixed and reversible) was 73, 80, 75 and 79 % respectively, in a patient based analysis of comparison group. The diagnostic accuracy of REF in predicting significant stenosis (>50 %) on ICA compared with SPECT was 72 versus 61 % and 85 versus 79 % in patient and vessel based analysis of comparison group, respectively. ROC curve analysis showed REF to be a better predictor of perfusion defects on SPECT compared with significant stenosis (>50 %) alone or stenosis combined with REF (P < 0.05). The computerized assessment of REF analysis is comparable to SPECT in predicting ischemia and a better predictor of significant stenosis than SPECT. This study also provides reference standard to define abnormal values.

Very small calcifications are detected and scored in the coronary arteries from small voxel MDCT images using a new automated/calibrated scoring method with statistical and patient specific plaque definitions.

A negative (zero) Agatston coronary calcium score (CCS) by current methods confers a very low risk for hard coronary events during the next years. However, controversy remains on how to use a negative score since some hard events still occur. We report on a new method with improved detection sensitivity for very small calcifications with the potential to more confidently rule out early atherosclerotic disease. Seventy-eight (78) patients with negative Agatston scores by conventional methods with 2.5 mm slices were selected from routine GE 64 MDCT scans. Each scan was reconstructed a second time from the same data to create 0.625 mm isotropic voxels. The 2.5 mm images were manually scored by the usual Agatston method using the GE SmartScore™ software. Both the 2.5 and 0.625 mm image sets were scored with a new automated and calibrated method (N-vivo™, Image Analysis). The software automatically computes dual scoring thresholds that are statistically defined and specific for each patient, scanner, and scan. The images were hybrid calibrated by simultaneous scanned phantoms in combination with in vivo blood/muscle references. The output reported the calibrated mass scores along with the number of plaques using 18 pt, 3-D connectivity criteria. A CCS Test phantom with known CaHA microspheres was used to validate the method. Twenty-three percent (18 of 78) of the patients with negative Agatston scores by the conventional method scored positive for coronary calcifications by the N-vivo method. The number of small plaques scored per patient varied from 1 to 4. One patient with a single small calcification suffered a hard coronary event during the CT scan. All of the detected plaques were located in the proximal heart. The conventional CCS method misclassified 23% of these patients as having negative coronary calcium scores. The N-vivo automated scoring method with small voxel CT images increased the detection sensitivity of small calcifications with no increase in radiation dose. Detection of small coronary calcified plaques occult to conventional scoring methods may increase the negative predictive power of calcium scoring and may improve plaque composition analysis.

Trabecular bone mineral density measurement using thoracic and lumbar quantitative computed tomography.

PURPOSE: To evaluate the agreement of bone mineral density (BMD) between lumbar (L) and individual thoracic (T) vertebrae and identify a standard thoracic spine level for BMD assessment in cardiac computed tomography (CT) images. MATERIALS AND METHODS: Three hundred subjects who underwent simultaneous chest and abdomen CT scans for clinical indications were included. A calibration phantom that extended from the first thoracic spine (T(1)) to the fifth lumbar (L(5)) was employed. Vertebral BMD were measured by QCT 5000 and NVivo systems. The association between three consecutive lumbar (L1-L3) and thoracic BMD (3T, initiation site equivalent to left main coronary caudally) was evaluated. RESULTS: There was a gradual decrease in BMD values from T(1) to L(3,) subsequently increasing in L(4) and L(5) in both genders. When stratified by gender, 3T BMD was significantly higher versus L(1-3) BMD (156.9 versus 141.9vmg/cm(3), P < .001) for women as well as for men (164.8 versus 151.0 mg/cm(3), P < .001). There is good correlation between 3T and L(1-3) BMD, the Pearson's correlation coefficients are 0.91 and 0.93 for women and men, respectively. We further analyzed the associations between L(1-3) and any individual spine of T(1)-L(5) and similar relationships were observed (r value, 0.62-0.98). The intraobserver, interobserver, and interscan variation measurement of thoracic quantitative CT was 2.5 (1.0, 95% CI 0.099-1.004); 2.6 (1.0, 95CI% 0.992-1.007), and 2.8% (1.0,95% 0.0994-1.008), respectively. CONCLUSION: The 3T BMD was highly correlated with L(1-3) BMD. Thoracic BMD can be measured during cardiac and lung CT imaging without need for additional participant burden or radiation dose. This highly reproducible methodology is actively being applied to large cohort studies to evaluate the prevalence of osteoporosis and track BMD over time.