Helical and single-slice conventional CT versus electron beam CT for the quantification of coronary artery calcification

Detection of small coronary calcifications in patients with Agatston coronary artery calcium score of zero

BACKGROUND

A coronary artery calcium score (CACS) of 0 is associated with a very low risk of cardiac event. However, the Agatston CACS may fail to detect very small or less dense calcifications. We investigated if an alteration of the Agatston criteria would affect the ability to detect such plaques.

METHODS

We evaluated 322 patients, 161 who had a baseline scan with CACS ​= ​0 and a follow-up scan with CACS>0 and 161 with two serial CACS ​= ​0 scans (control group), to identify subtle calcification not detected in the baseline scan because it was not meeting the Agatston size and HU thresholds (≥1 ​mm² and ≥130HU). Size threshold was set to <1 ​mm² and the HU threshold modified in a stepwise manner to 120, 110, 100 and 90. New lesions were classified as true positive or false positive(noise) using the follow-up scan.

RESULTS

We identified 69 visually suspected subtle calcified lesions in 65/322 (20.2%) patients with CAC ​= ​0 by the Agatston criteria. When size threshold was set as <1 ​mm² and HU ​≥ ​130, 36 lesions scored CACS>0, 34 (94.4%) true positive and 2 (5.6%) false positive. When decrease in HU (120HU, 110HU, 100HU, and 90HU) threshold was added to the reduced size threshold, the number of lesions scoring>0 increased (46, 55, 59, and 69, respectively) at a cost of increased false positive rate (8.7%, 20%, 22%, and 30.4% respectively). Eliminating size or both size and HU threshold to ≥120HU correctly reclassified 9.6% and 12.1% of patients respectively.

CONCLUSION

Eliminating size and reducing HU thresholds to ≥120HU improved the detection of subtle calcification when compared to the Agatston CACS method.

Comparison of Calcium Scoring Between 64-Multidetector Computed Tomography and 320-Multidetector Computed Tomography Using a Cardiac Phantom: Achieving Consistent Image Quality With Dose Optimization

ABSTRACT

The purpose of this study was to evaluate the relationship between radiation dose and noise level on various coronary calcium scoring protocols between 64-multidetector computed tomography (MDCT) and 320-MDCT. The cardiac QRM phantoms (1 small size and 1 medium size) were used in this study. Lower-dose imaging protocols were proposed for optimization with the parameters of 120 kVp and 10 mAs for small-size phantom (0.336 mSv) in 64-MDCT imaging and small-size phantom (0.2 mSv) in 320-MDCT case, and 120 kVp and 80 mAs for medium-size phantom (2.73 mSv) in 64-MDCT imaging and medium-size phantom (1.58 mSv) in 320-MDCT case. Our results suggest that people can apply lower-dose protocols in the clinical use for early diagnosis of coronary disease without sacrificing diagnostic accuracy.

Elevated serum cartilage oligomeric matrix protein and the metalloproteinase-ADAMTS7 levels are associated with vascular calcification in maintenance hemodialysis patients

BACKGROUND

Vascular calcification is common in maintenance hemodialysis (HD) patients. Recent studies showed that cartilage oligomeric matrix protein (COMP) could protect blood vessels from calcification, but the role of ADAMTS7 was opposite. We aimed to investigate the relationship between serum COMP, ADAMTS7 levels and vascular calcification scores in HD patients.

METHODS

Serum COMP and ADAMTS7 levels were tested by ELISA and we compared calcification scores between high and low COMP groups, also between high and low ADAMTS7 groups. We also investigated the differences of serum COMP and ADAMTS7 levels between mild and severe vascular calcification groups. The relationship between serum COMP and ADAMTS7 levels was analyzed in the end.

RESULTS

Serum COMP and ADAMTS7 levels were both higher in HD patients than in control (29.63 vs 14.23 ng/mL, P = .002, 11.12 vs 2.40 ng/mL, P = .005). Serum COMP levels in severe vascular calcification (VC) group were higher than in mild VC (43.13 ± 28.77 vs 26.75 ± 18.22 ng/mL, P = .010). Serum ADAMTS7 levels were positively correlated with radial and digital arteries (small arteries) calcification scores (r = .249, P = .033). And serum COMP and ADAMTS7 levels were positively correlated (r = .348, P = .026).

CONCLUSIONS

Serum COMP and ADAMTS7 levels were probably associated with vascular calcification scores in HD respectively.

Association between vascular calcification assessed by simple radiography and non-fatal cardiovascular events in hemodialysis patients

BACKGROUND

Vascular calcification (VC) is one of the factors associated with cardiovascular mortality in hemodialysis (HD) patients. Recommendations concerning screening for VC differ. Possible ability to prevent and reversibility of VC are major subjects on debate whether screening for VC could improve outcomes of renal patients. The objective of the study was to evaluate the significance of simple vascular calcification score (SVCS) based on plane radiographic films and to test its association with non-fatal cardiovascular events in patients on chronic HD.

METHODS

A study population consisted of 95 prevalent HD patients in the HD unit of Hospital of Lithuanian University of Health sciences Kaunas Clinics. Clinical data and laboratory tests information were collected from medical records. SVCS was evaluated as it is described by Adragao et al. After measurement of VC, HD patients were observed for novel non-fatal cardiovascular events.

RESULTS

Patients were divided into two groups: SVCS≥3 (57 patients [60%]) and <3 (38 patients [40%]). The Kaplan-Meier survival curves show a significant difference in non-fatal cardiovascular events in the group with SVCS≥3 vs. <3 group (26.3% vs. 7.8%; log rank 5,49; P=0.018). Multivariate Cox regression analysis confirmed a negative impact of VC, hyperphosphatemia, and lower ejection fraction on cardiovascular events. No statistically significant differences were observed comparing parameters of Ca-P metabolism disorders between groups with different SVCS. On separate analysis, the presence of VC in hands was also associated with higher rate of novel cardiovascular events (score 0 goup-5 events [10.6%] vs. score≥1 group-13 events [27%], log rank P=0.035).

CONCLUSION

VC assessed by simple and inexpensive radiological method was an independent predictor of novel non-fatal cardiovascular events in HD patients.

Radiation dose reduction at coronary artery calcium scoring by using a low tube current technique and hybrid iterative reconstruction

PURPOSE

The aim of this study was to compare the accuracy of coronary artery calcium scoring (CACS) on cardiac computed tomographic images using hybrid iterative reconstruction (hIR) and a low tube current as well as on images acquired with a filtered back projection (FBP) algorithm and a normal tube current.

SUBJECTS AND METHODS

Patients (N = 77) with suspected coronary artery disease were subjected to 2 CACS evaluations based on their Agatston, volume, and mass scores. One CACS evaluation was performed on images obtained with a 364-mA tube current and reconstructed with FBP; the other was performed on images obtained with a 73-mA tube current and reconstructed with hIR at iDose4. All scans were performed with the prospective electrocardiogram-triggered method using a 256-slice computed tomographic scanner (Brilliance iCT; Philips). We assessed agreement between calcium scores obtained with FBP and with IR using the percentage difference and Bland-Altman analysis.

RESULTS

The effective radiation doses for CACS at 80 mA s with FBP and at 16 mA s with IR were 1.20 and 0.24 mSv, respectively (k = 0.014). The mean Agatston, volume, and mass scores at 80 mA s with FBP as well as at 16 mA s with IR were 390.7, 146.5, and 63.2 as well as 377.7, 142.5, and 62.2, respectively. The percentage difference between FBP and hIR for the Agatston, volume, and mass score was 20.7%, 20.7%, and 27.1%, respectively. Bland-Altman analysis showed that there was no systemic bias.

CONCLUSIONS

The radiation dose for CACS can be reduced at a low tube current and hIR without affecting the calcium score.

Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

OBJECTIVE

Cardiac CT allows the detection and quantification of coronary artery calcification (CAC). Electron-beam CT (EBCT) has been widely replaced by high-end CT generations in the assessment of CAC. The aim of this study was to compare the CAC scores derived from an EBCT with those from a dual-source CT (DSCT).

METHODS

We retrospectively selected 92 patients (61 males; mean age, 60.7 ± 12 years) from our database, who underwent both EBCT and DSCT. CAC was assessed using the Agatston score by two independent readers (replicates: 1, 2; 3=mean of reading 1 and 2).

RESULTS

EBCT scores were on average slightly higher than DSCT scores (281 ± 569 vs 241 ± 502; p<0.05). In regression analysis R(2)-values vary from 0.956 (1) to 0.966 (3). We calculated a correction factor as EBCT=(DSCT+1)(1.026)-1. When stratifying into CAC categories (0, 1-99, 100-399, 400-999 and ≥1000), 79 (86%) were correctly classified. From those with positive CAC scores, 7 out of 61 cases (11%, κ=0.81) were classified in different categories. Using the corrected DSCT CAC score, linear regression analysis for the comparison to the EBCT results were r=0.971 (p<0.001), with a mean difference of 6.4 ± 147.8. Five subjects (5.4%) were still classified in different categories (κ=0.84).

CONCLUSION

CAC obtained from DSCT is highly correlated with the EBCT measures. Using the calculated correction factor, agreement only marginally improved the clinical interpretation of results. Overall, for clinical purposes, face value use of DSCT-derived values appears as useful as EBCT for CAC scoring.

Impact of coronary calcium on outcome following sirolimus-eluting stent implantation

There remain a small but sizable number of patients who develop restenosis after sirolimus-eluting stent (SES) implantation. However, the cause of SES restenosis has not been fully elucidated. The study population consisted of 52 patients with 69 lesions who underwent noninvasive coronary imaging by 64-slice multidetector computed tomography before SES deployment. Agatston calcium scores in target lesions were measured. All patients underwent follow-up coronary angiography at 8 months. Three coronary segments (in stent, proximal edge, and distal edge) were analyzed by quantitative coronary angiography. Agatston calcium score in target lesions averaged 214.7. Late lumen losses in the proximal edge, stent, and distal edge were 0.16 ± 0.45, 0.47 ± 0.58, and 0.07 ± 0.29 mm, respectively. Lesions with restenosis at follow-up showed a trend to produce higher preprocedural calcium scores (629) compared to those without restenosis (153, p = 0.08). There was a significant positive correlation between lesion calcium score and in-stent late lumen loss (r = 0.47, p <0.01). In conclusion, assessment of coronary calcium by multidetector computed tomography might be useful to predict outcomes after SES implantation.

Non-invasive detection of vulnerable coronary plaque

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and non-invasive imaging techniques have shown the potential to identify these high-risk plaques. Non-invasive imaging with magnetic resonance imaging, computed tomography and positron emission tomography holds the potential to differentiate between low- and high-risk plaques. There have been significant technological advances in non-invasive imaging modalities, and the aim is to achieve a diagnostic sensitivity for these technologies similar to that of the invasive modalities. Molecular imaging with the use of novel targeted nanoparticles may help in detecting high-risk plaques that will ultimately cause acute myocardial infarction. Moreover, nanoparticle-based imaging may even provide non-invasive treatments for these plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque nor have they been shown to definitively predict outcome. Further trials are needed to provide more information regarding the natural history of high-risk but non-flow-limiting plaque to establish patient specific targeted therapy and to refine plaque stabilizing strategies in the future.

Acromegaly per se does not increase the risk for coronary artery disease

CONTEXT

Information about the risk and course of coronary artery disease (CAD) in acromegaly is limited.

OBJECTIVE

To evaluate CAD risk in acromegalic patients at diagnosis and after successful treatment during follow-up.

SUBJECTS AND METHODS

Twenty-five consecutive patients (age 45.1+/-10.6 years, 15 women) were studied at the time of diagnosis, and 19 patients were re-evaluated after 4.6+/-1.1 years. The European Society of Cardiology (ESC) risk score was calculated, and a cardiac computed tomography was performed for detection and quantification (Agatston score (AS)) of coronary artery calcium (CACs). Fifty age-, sex-, and CAD risk-matched subjects and CAC data from the population-based Heinz Nixdorf Recall (HNR) study served as controls.

RESULTS

In 21 of the 25 patients, the 10-year risk of developing CAD according to the ESC risk score was low (<10%) and high (>20%) in four patients. The AS was lower than in controls (2.6+/-7.9 vs 66+/-182; P=0.014) and less patients had a positive CAC (AS>0) (20 vs 48%, P=0.024), which in the acromegalic patients was less than expected from the HNR study. The AS did not correlate with GH excess or disease duration. In 19 acromegalic patients, who were in remission and re-evaluated after 4.6+/-1.1 years, the ESC risk (P=0.102) and the AS (P=0.173) did not change significantly and no symptomatic CAD event occurred.

CONCLUSION

CAD risk in newly diagnosed acromegalic patients was low and remained stable after successful treatment. CAC was lower than in controls suggesting that GH excess per se does not carry an additional CAD risk.

Assessment of coronary artery calcium by using volumetric 320-row multi-detector computed tomography: comparison of 0.5 mm with 3.0 mm slice reconstructions

The purpose of this study was to assess the performance of 0.5 versus 3.0 mm slice reconstructions in depicting coronary calcium with special attention to patients having zero calcium scores at 3.0 mm reconstructions by using computed tomography (CT). Imaging was performed by volumetric 320-detector row CT. Scans of 100 patients with a negative and 100 patients with a positive Agatston score at 3.0 mm reconstructions were consecutively selected. Non-overlapping volume sets with 3.0 and 0.5 mm slice thickness were reconstructed from the same raw data and Agatston and volume scores were obtained. The Wilcoxon signed ranks test was used to determine statistical differences between 3.0 and 0.5 mm calcium scores. Agatston and volume scores obtained at 0.5 mm were significantly higher than at 3.0 mm reconstructions (mean Agatston score: 266 +/- 495 vs. 231 +/- 461. Mean volume score: 223 +/- 399 vs. 206 +/- 385, both P < 0.01). In 21% of patients with zero 3.0 mm Agatston scores, a positive Agatston and/or volume score was found at 0.5 mm reconstructions. With volumetric 320-detector row CT, prospective ECG-triggered calcium scoring at 0.5 mm compared to 3.0 mm reconstructions leads to an increase in Agatston and volume scores and small amounts of coronary calcium are earlier depicted. This may be of special interest in patients with zero calcium scores with traditional 3.0 mm measures, where 0.5 mm reconstructions may help in superior depicting or ruling out coronary artery disease.

Current status of vulnerable plaque detection

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes (ACS) and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and noninvasive imaging techniques have shown the potential to identify these high-risk plaques. The anatomical characteristics of the vulnerable plaque such as thin cap fibroatheroma and lipid pool can be identified with angioscopy, high frequency intravascular ultrasound, intravascular MRI, and optical coherence tomography. Efforts have also been made to recognize active inflammation in high-risk plaques using intravascular thermography. Plaque chemical composition by measuring electromagnetic radiation using spectroscopy is also an emerging technology to detect vulnerable plaques. Noninvasive imaging with MRI, CT, and PET also holds the potential to differentiate between low and high-risk plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque neither has been shown to definitively predict outcome. Nevertheless in contrast, there has been a parallel development in the physiological assessment of advanced atherosclerotic coronary artery disease. Thus recent trials using fractional flow reserve in patients with modest non flow-limiting stenoses have shown that deferral of PCI with optimal medical therapy in these patients is superior to coronary intervention. Further trials are needed to provide more information regarding the natural history of high-risk but non flow-limiting plaque to establish patient-specific targeted therapy and to refine plaque stabilizing strategies in the future.

Recent technologic advances in multi-detector row cardiac CT

Recent technical advances in multi-detector row CT have resulted in lower radiation dose, improved temporal and spatial resolution, decreased scan time, and improved tissue differentiation. Lower radiation doses have resulted from the use of pre-patient z collimators, the availability of thin-slice axial data acquisition, the increased efficiency of ECG-based tube current modulation, and the implementation of iterative reconstruction algorithms. Faster gantry rotation and the simultaneous use of two x-ray sources have led to improvements in temporal resolution, and gains in spatial resolution have been achieved through application of the flying x-ray focal-spot technique in the z-direction. Shorter scan times have resulted from the design of detector arrays with increasing numbers of detector rows and through the simultaneous use of two x-ray sources to allow higher helical pitch. Some improvement in tissue differentiation has been achieved with dual energy CT. This article discusses these recent technical advances in detail.

Prevalence of non-cardiac findings in a large series of patients undergoing cardiac multi-detector computed tomography scans

The purpose of our study was to determine the prevalence of non-cardiac findings in a large series of patients undergoing contrast-enhanced cardiac multi-detector computed tomography (MDCT) scans. Non-cardiac findings were classified according to the organ of involvement and level of significance. We retrospectively reviewed scans and reports of 1,061 patients performed between 1 April 2004 and 31 April 2006. Non-cardiac findings were considered significant if they warranted further radiological or clinical follow-up. A total of 103 non-cardiac findings were reported in 85 (8.0%) of the 1,061 patients. Of these lesions, 48 (46.7%) were significant and 55 (53.3%) were not. The significant lesions were found in 33 of the 1,061 patients (3.1%). Among the significant abnormalities, the three most common were pulmonary nodules (16.7%), emphysema (16.7%) and possible hepatic carcinomas (12.6%). Patients with non-cardiac findings were significantly older than those without (mean age 60 +/- 6 years vs. 55 +/- 8 years; P < 0.0001). The prevalence of active smoking was significantly higher in patients with non-cardiac findings (28.2 vs. 17.8%; P = 0.03). The prevalence of non-cardiac abnormalities detected by cardiac MDCT was 8% and about half of these findings were deemed significant. These lesions commonly occurred in the lungs and the liver. Age and active smoking were predictive of the presence of non-cardiac abnormalities.

Coronary calcium screening using low-dose lung cancer screening: effectiveness of MDCT with retrospective reconstruction

OBJECTIVE

The purpose of our study was to show the usefulness of nongated low-dose chest CT for coronary screening by comparing the results of coronary artery calcium measurement with that of dedicated calcium-scoring CT.

MATERIALS AND METHODS

One hundred twenty-eight consecutive participants (all men; mean age, 52 +/- 7 years) underwent low-dose chest CT and calcium-scoring CT with prospective ECG gating using 40-MDCT. Low-dose chest CT volume data were reconstructed as 25-cm field of view and three slice thicknesses: 1, 2.5, and 5 mm. For each examination, the lesion area, Agatston calcium score, and calcium mass were measured at 90- and 130-H thresholds. All measurements (130-H threshold) from the calcium-scoring CT were used as reference standards. Spearman's correlation test was used to compare the results.

RESULTS

Among the low-dose chest CT examinations, sensitivity was best determined with a 1-mm slice thickness at 130 H and 2.5-mm slice thickness at 90 H. Specificity was best determined with a 5-mm slice thickness at 130 H. Accuracy (90%) was best determined with a 2.5-mm slice thickness at 130 H. Of all protocols, calcium area, score, and mass from a 2.5-mm slice thickness at 130 H correlated best with the reference results (r = 0.89 for all three criteria).

CONCLUSION

Using a low radiation dose and nongated MDCT, we can detect coronary artery calcium and obtain results comparable to those obtained with dedicated calcium-scoring CT that uses a higher dose and ECG gating.

Measurement of coronary calcium scores by electron beam computed tomography or exercise testing as initial diagnostic tool in low-risk patients with suspected coronary artery disease

We determined the efficiency of a screening protocol based on coronary calcium scores (CCS) compared with exercise testing in patients with suspected coronary artery disease (CAD), a normal ECG and troponin levels. Three-hundred-and-four patients were enrolled in a screening protocol including CCS by electron beam computed tomography (Agatston score), and exercise testing. Decision-making was based on CCS. When CCS>or=400, coronary angiography (CAG) was recommended. When CCS<10, patients were discharged. Exercise tests were graded as positive, negative or nondiagnostic. The combined endpoint was defined as coronary event or obstructive CAD at CAG. During 12+/-4 months, CCS>or=400, 10-399 and <10 were found in 42, 103 and 159 patients and the combined endpoint occurred in 24 (57%), 14 (14%) and 0 patients (0%), respectively. In 22 patients (7%), myocardial perfusion scintigraphy was performed instead of exercise testing due to the inability to perform an exercise test. A positive, nondiagnostic and negative exercise test result was found in 37, 76 and 191 patients, and the combined endpoint occurred in 11 (30%), 15 (20%) and 12 patients (6%), respectively. Receiver-operator characteristics analysis showed that the area under the curve of 0.89 (95% CI: 0.85-0.93) for CCS was superior to 0.69 (95% CI: 0.61-0.78) for exercise testing (P<0.0001). In conclusion, measurement of CCS is an appropriate initial screening test in a well-defined low-risk population with suspected CAD.

Subclinical Cardiovascular Disease Markers Applicable to Studies of Oral Health: Multiethnic Study of Atherosclerosis

Recent findings associate periodontal disease with established coronary heart disease (CHD) and with disorders of the carotid artery. Besides measures of the carotid artery, a number of other noninvasive subclinical markers of cardiovascular disease exist and are summarized here. Included are computed tomography (CT) of the coronary arteries, ultrasound of the carotid arteries, echocardiography, magnetic resonance imaging (MRI), ankle-brachial index, microalbuminuria, and other biochemical measures of kidney dysfunction, flow-mediated dilation in the brachial artery, and pulse wave form analysis. Use of these measures may simplify and add depth to studies of oral health and cardiovascular disease. However, it is noted that the measures are not highly correlated with each other (based on 6,814 persons in the Multiethnic Study of Atherosclerosis, Pearson correlations among the above subclinical measures, range from about 0.1-0.4), do not include propensity for the important atherosclerotic phase of plaque rupture, and do not fully substitute for studies of clinical cardiovascular disease endpoints.

Evaluation of automated attenuation-based tube current adaptation for coronary calcium scoring in MDCT in a cohort of 262 patients

The aim of our study was to evaluate attenuation-based tube current adaptation in coronary calcium scoring using ECG-gated multi-detector-row CT (MDCT). A total of 262 patients underwent non-enhanced cardiac MDCT. Group 1 was scanned using a standard protocol with 120 kV and 150 mAs(eff). Groups 2-4 were scanned using an attenuation-based dose-adaptation template (CARE Dose) with different effective reference mAs settings (150, 180, 210 mAs(eff)). Body-mass index (BMI) and CT-dose index values were calculated for each patient. Image noise and subjective image quality were assessed. Regression analysis was performed, and the variation coefficient of image noise was determined. Compared to the standard scan protocol a dose reduction of 31.1% for group 2 and 20.1% for group 3 was observed. Measurement variation of image noise was smaller for the attenuation-based dose adaptation protocols (group 2-4) (16.2-17.1%) compared to the standard scan protocol (32.3%). Regression analysis of groups 2-4 showed better correlation with improved dose usage based on BMI (all P <or= 0.001). Median image quality was "excellent" in groups 2-4 and "good" in group 1. Automated attenuation-based tube current adaptation in coronary calcium scoring is technically feasible, can decrease patient dose, and reduces variation in image noise as a sign of improved dose usage.

Coronary calcium scoring with MDCT: The radiation dose to the breast and the effectiveness of bismuth breast shield

OBJECTIVE

The purpose of our study was to determine the breast radiation dose during coronary calcium scoring with multidetector computerized tomography (MDCT). We also evaluated the degree of dose reduction by using a bismuth breast shield when performing coronary calcium scoring with MDCT.

MATERIALS AND METHODS

The dose reduction achievable by shielding the adult (35 years or older) female breasts was studied in 25 women who underwent coronary calcium scoring with MDCT. All examinations were performed with a 16-MDCT scanner. To compare the shielded versus unshielded breast dose, the examinations were performed with (right breast) and without (left breast) breast shielding in all patients. With this technique the superficial breast doses were calculated. To determine the average glandular breast radiation dose, we imaged an anthropomorphic dosimetric phantom into which calibrated dosimeters were placed to measure the dose to the breast. The phantom was imaged using the same protocol. Radiation doses to the breasts with and without the breast shielding were measured and compared using the Student's t-test.

RESULTS

The mean radiation doses with and without the breast shield were 5.71+/-1.1 mGy versus 9.08+/-1.5 mGy, respectively. The breast shield provided a 37.12% decrease in radiation dose to the breast with shielding. The difference between the dose received by the breasts with and without bismuth shielding was significant, with a p-value of less than 0.001.

CONCLUSION

The high radiation during MDCT greatly exceeds the recommended doses and should not be underestimated. Bismuth in plane shielding for coronary calcium scoring with MDCT decreased the radiation dose to the breast. We recommend routine use of breast shields in female patients undergoing calcium scoring with MDCT.

Diagnostic value of 64-slice multi-detector row cardiac CTA in symptomatic patients

Cardiac multi-detector-row computed tomography (MDCT) angiography has shown high levels of sensitivity and especially negative predictive value regarding the diagnosis of coronary artery disease (CAD). This study was designed to determine the value of a 64-slice-MDCT scanner in comparison to invasive coronary angiography for the detection of CAD in a population of symptomatic patients. Fifty-one patients with suspected CAD underwent conventional coronary angiography and ECG-gated cardiac 64-slice-MDCT angiography with a rotation time of 330 ms, a collimation of 64x0.6 mm and a slice thickness of 0.75 mm. Blinded patient- and segment-based analysis was performed for the detection of stenoses >or=70% of the vessel lumen. 95% of all coronary segments were assessable by MDCT angiography. Patient-based (segment-based) analysis revealed a sensitivity of 97.8% (86.7%), specificity of 50% (95.2%), positive predictive value of 93.6% (75.2%) and negative predictive value of 75% (97.7%). Inter-rater agreement revealed a kappa-value of 0.558 (0.722). In this symptomatic patient group a 64-slice-MDCT scanner shows good agreement on a segment-based analysis but only moderate agreement on a patient-based analysis. The diagnostic accuracy of 64-slice-MDCT coronary angiography is negatively influenced by the high pre-test probability of this symptomatic patient collective.

The accuracy of 1- and 3-mm slices in coronary calcium scoring using multi-slice CT in vitro and in vivo

The accuracy of coronary calcium scoring using 16-row MSCT comparing 1- and 3-mm slices was assessed. A thorax phantom with calcium cylinder inserts was scanned applying a non-enhanced retrospectively ECG-gated examination protocol: collimation 12 x 0.75 mm; 120 kV; 133 mAs(eff). Thirty-eight patients were examined using the same scan protocol. Image reconstruction was performed with an effective slice thickness of 3 and 1 mm. The volume score, calcium mass and Agatston score were determined. Image noise was measured in both studies. The volume score and calcium mass varied less than the Agatston score. The overall measured calcium mass compared to the actual calcium mass revealed a relative difference of +2.0% for 1-mm slices and -1.2% for 3-mm slices. Due to increased image noise in thinner slices in the patient study (26.1 HU), overall calcium scoring with a scoring threshold of 130 HU was not feasible. Interlesion comparison showed significantly higher scoring results for thinner slices (all P<0.001). A similar accuracy comparing calcium scoring results of 1- and 3-mm slices was shown in the phantom study; therefore, the potentially necessary increase of the patient's dose in order to achieve assessable 1-mm slices with an acceptable image-to-noise-ratio appears not to be justified.

A simple score predicts future cardiovascular events in an inception cohort of dialysis patients

Vascular calcifications are very common in dialysis patients and have been shown to be associated independently with outcome. However, all of these studies used prevalent patients on dialysis since many years. We investigated vascular calcifications in an inception cohort of dialysis patients and followed them for cardiovascular disease outcomes during an average observation period of 66 months. One hundred and fifty-four Caucasian dialysis patients were enrolled in one Austrian dialysis center. Standardized plain radiographs from the pelvis and calves were carried out in all patients at the start of dialysis therapy. Vascular calcifications were assessed by a single radiologist. At the start of renal replacement therapy, 67.5% of the patients showed vascular calcifications. During follow-up, 29.9% of patients suffered a cardiovascular event. An additive 'vascular risk score', constructed from the presence of vascular calcifications and/or previous cardiovascular events before the start of dialysis treatment, showed the strongest independent association with cardiovascular events in the Cox regression model adjusted for various risk factors. The presence of each of these two conditions was associated with a hazard ratio of 2.03 (95% confidence interval 1.19-3.46) and a hazard ratio twice as high if both conditions were present. In summary, vascular calcifications on plain X-rays of pelvis and calves are largely present in incident dialysis patients. A history of a cardiovascular event in the predialysis period together with vascular calcifications at the beginning of dialysis therapy is a more powerful predictor of a cardiovascular event than age, smoking, diabetes, or other traditional risk factors.

Is calcium the key for the assessment of progression/regression of coronary artery disease?

Coronary calcium scoring has become a common test for cardiovascular risk stratification.

Concordance of Coronary Artery Calcium Estimates Between MDCT and Electron Beam Tomography

OBJECTIVE

The objective of our study was to compare MDCT with electron beam tomography (EBT) for the quantification of coronary artery calcification (CAC).

MATERIALS AND METHODS

Sixty-eight patients underwent both MDCT and EBT within 2 months for the quantification of CAC. The images were scored in a blinded fashion and independently by two observers with a minimum of 7 days between the interpretations of images obtained from one scanner type to the other.

RESULTS

Presence versus absence of CAC was discordant by EBT versus MDCT in 6% (n = 4) of the cases by observer 1, with one of these cases also discordant by observer 2. All cases except one (aortic calcium misidentified as CAC) were among those with a mean Agatston score of less than 5 present on EBT but absent on MDCT. EBT and MDCT scores correlated well (r = 0.98-0.99). The relative median variability between EBT and MDCT for the Agatston score was 24% for observer 1 and 27% for observer 2 and was 18% and 14%, respectively, for volume score (average for both observers: 27% for Agatston score and 16% for volume score). Scores were higher for EBT than MDCT in approximately half of the cases, with little systematic difference between the two (median EBT-MDCT difference: Agatston score, -0.55; volume score, 3.4 mm3). The absolute median difference averaged for the two observers was 28.75 for the Agatston score and 15.4 mm3 for the volume score.

CONCLUSION

Differences in CAC measurements using EBT and MDCT are similar to interscan differences in CAC measurements previously reported for EBT or for other MDCT scanners individually.

Effect of Varying Slice Thickness on Coronary Calcium Scoring With Multislice Computed Tomography in Vitro and in Vivo

OBJECTIVES

To compare coronary calcium scoring results (calcium volume, calcium mass, Agatston score, and number of lesions) of different slice thicknesses using a 16-slice CT (MSCT) scanner.

MATERIALS AND METHODS

A nonmoving anthropomorphic thorax phantom with calcium cylinders of different sizes and densities was scanned 30 times with repositioning applying a standardized retrospectively ECG-gated MSCT (SOMATOM Sensation 16; Siemens, Forchheim, Germany) scan protocol: collimation 12 x 0.75 mm, tube voltage 120 kV, effective tube current time-product 133 mAs(eff). Fifty patients (29 male; age 57.2 +/- 8.4 years) underwent a nonenhanced scan applying the same scan protocol. Two image sets (effective slice thicknesses 3 mm and 1 mm) were reconstructed at 60% of the RR interval. Image noise was measured in both studies. Calcium volume, calcium mass and Agatston score were calculated using a commercially available software tool.

RESULTS

Due to increased image noise in thinner slices, calcium scoring in all scans was performed applying a scoring threshold of 350 HU. In the phantom study, 1-mm slices showed significantly higher scoring results in respect to calcium volume (+8.2%), calcium mass (+12.5%), and Agatston score (+5.3%) (all P < 0.0001). In the patient study, 27 patients had coronary calcifications in 3-mm slices, and 31 patients had coronary calcifications in 1-mm slices. Thinner slices showed significantly higher scoring results in respect to volume (+47.1%), mass (+47.2%), and Agatston score (+29.7%) (all P < 0.0001).

CONCLUSIONS

When comparing 3-mm and 1-mm slices in coronary calcium scoring in MSCT, thinner slices lead to significantly increased scoring results.

Usefulness of helical computed tomography in detection of mitral annular calcification as a marker of coronary artery disease

BACKGROUND

Mitral annulus calcification (MAC) may be a form of atherosclerosis. The goal of the present work was to investigate whether helical CT can determine the presence of MAC and to clarify its possible association with coronary artery disease (CAD) in elderly patients.

DESIGN AND METHODS

Three hundred and twenty-nine consecutive elderly patients (165 men and 164 women, age range 60-79 years) underwent double helical CT of the heart to determine MAC and coronary calcifications (CC) according to a previously described protocol.

RESULTS

MAC was documented in 60 patients (25 men, 35 women; mean age 69 +/- 4.5 years, range 60-78 years). The non-MAC group (control) included 269 patients (140 men, 129 women; mean age 67 +/- 4.6 years, range 60-79 years). Age was the only risk factor which had significant association with MAC (p = 0.01). A significant difference was found between MAC and control group for mean total CC score and advanced CC (total CC > 300) (323 +/- 565 vs. 184 +/- 429, p = 0.033 and 30% vs. 16%, p = 0.017, respectively). A significant difference was also found between groups for the prevalent proven CAD (30% vs. 16%, p = 0.008). Stepwise logistic regression analysis identified age [odds ratio (OR) 3.3, 95% confidence interval (CI) 1.7-6.4, p < 0.001)], gender (male) (OR 3.1, 95% CI 1.6-6.0, p = 0.001), and MAC (OR 2.4, 95% CI 1.2-5.0, p = 0.016) as the independent variables significantly associated with CAD. The independent variables significantly associated with advanced CC (TCS > 300) were MAC (OR 2.6, 95% CI 1.3-5.2, p = 0.005), gender (male) (OR 2.3, 95% CI 1.2-4.2, p = 0.012) and age (OR 1.9, 95% CI 1.0-3.7, p = 0.052).

CONCLUSIONS

Our study demonstrated the usefulness of helical computed tomography in the detection of mitral annular calcification as an additional marker of prevalent CAD. However, the diagnostic significance of the MAC detection is relatively minor and should not be considered as a direct proof for coronary atherosclerosis.

Update on using coronary calcium screening by computed tomography to measure risk for coronary heart disease

Coronary artery disease (CAD) is the number one killer of adults in the United States, claiming one-half million deaths annually. Early detection and prevention strategies clearly remain a top priority for health care providers in order to reduce the high mortality rate of heart disease. As an unequivocal reflection of arteriosclerosis, coronary arterial calcium (CAC) may provide a means to qualitatively assess the overall disease severity and likewise serve as a means to assess risk for CHD. It is known that patients with heavy calcium burdens have more advanced CAD, a concomitantly a higher likelihood of coronary stenoses, and a concomitant higher risk for acute cardiac events. Computed tomography has been shown to be an accurate, non-invasive method to quantify coronary calcification burden in patients. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that CAC measurements accurately reflect disease severity and can be useful to assess individual risk for CHD. The purpose of this article is to summarize the currently available evidence that has attempted to validate CAC screening as a screening exam and risk predictor for coronary heart disease.

Advances in cardiovascular CT imaging: CT clinical imaging

Recent advances in cardiovascular CT imaging have dramatically changed the way we evaluate cardiac and great vessel disease. The superb spatial and faster temporal resolutions of the newer scanners, have allowed CT to gain acceptance not only in defining cardiac and great vessel anatomy but also has allowed its entry into the field of functional and perfusion imaging. This paper reviews the current status of CT in clinical imaging of the heart and great vessels.

Calcified coronary artery plaque measurement with cardiac CT in population-based studies: standardized protocol of Multi-Ethnic Study of Atherosclerosis (MESA) and Coronary Artery Risk Development in Young Adults (CARDIA) study

Calcified coronary artery plaque, measured at cardiac computed tomography (CT), is a predictor of cardiovascular disease and may play an increasing role in cardiovascular disease risk assessment. The Multi-Ethnic Study of Atherosclerosis (MESA) and the Coronary Artery Risk Development in Young Adults (CARDIA) study of the National Heart, Lung, and Blood Institute are population-based studies in which calcified coronary artery plaque was measured with electron-beam and multi-detector row CT and a standardized protocol in 6814 (MESA) and 3044 (CARDIA study) participants. The studies were approved by the appropriate institutional review board from the study site or agency, and written informed consent was obtained from each participant. Participation in the CT examination was high, image quality was good, and agreement for the presence of calcified plaque was high (kappa = 0.92, MESA; kappa = 0.77, CARDIA study). Extremely high agreement was observed between and within CT image analysts for the presence (kappa > 0.90, all) and amount (intraclass correlation coefficients, >0.99) of calcified plaque. Measurement of calcified coronary artery plaque with cardiac CT is well accepted by participants and can be implemented with consistently high-quality results with a standardized protocol and trained personnel. If predictive value of calcified coronary artery plaque for cardiovascular events proves sufficient to justify screening a segment of the population, then a standardized cardiac CT protocol is feasible and will provide reproducible results for health care providers and the public.

CT for imaging coronary artery disease: defining the paradigm for its application

Current generation multidetector-row CT (MDCT) enables high-resolution, motion-free imaging of the heart within a single, short breath-hold. MDCT allows highly accurate and reproducible quantification of coronary artery calcium, a marker that has been used for the detection, exclusion and monitoring of coronary atherosclerosis. The exact role of coronary calcium measurements for cardiac risk stratification remains unclear to date. At contrast enhanced MDCT coronary angiography coronary arteries can be visualized with unprecedented detail. The accurate non-invasive assessment of the presence and degree of coronary artery stenosis appears within reach. With increasing accuracy MDCT enables non-invasive patency evaluation of coronary artery bypass grafts and coronary stents. The cross-sectional nature of contrast enhanced MDCT coronary angiography allows assessment of the vessel wall and may permit more accurate quantification of total atherosclerotic plaque burden than measuring calcified components alone. For a limited time, future technical improvement will be pursued mainly by accelerated gantry rotation speed and additional detector rows. However, novel concepts of CT image acquisition are already under investigation and may bring about yet another quantum leap for medical CT. This communication discusses potential approaches for the beneficial utilization of MDCT for the assessment of patients with known or suspected coronary heart disease.

Association of traditional and nontraditional cardiovascular risk factors with coronary artery calcification

Coronary artery calcification assessed by computed tomography is an emerging marker of coronary atherosclerosis. The authors examined the association of coronary calcium scores with traditional and nontraditional cardiovascular risk factors. In 1999-2000, they measured coronary artery calcium in 360 participants free of known coronary artery disease who had participated in 2 centers of the Atherosclerosis Risk in Communities (ARIC) Study. They related coronary calcium scores to risk factors measured in 1987-1989. Most traditional risk factors were associated with the coronary calcium score. For example, the multivariately adjusted odds ratio for an elevated score (> or = 100 versus < 100) was 3.5-fold greater per 10 years of age, 3.2-fold greater in men than in women, 3.1-fold greater with diabetes (statistically nonsignificant), and 1.4- to 1.7-fold greater per standard deviation greater increments of plasma cholesterol and pack-years of cigarettes smoked. Carotid artery intima-media thickness also was positively associated with coronary calcification. In contrast, a wide variety of hemostatic and inflammatory markers and serum chemistry values were unrelated to calcium scores. These findings reaffirmed the established role of traditional risk factors in the etiology of coronary artery disease, as assessed by computed tomography, but did not identify any important nontraditional risk factors.

Multidetector-row computed tomography and magnetic resonance imaging of atherosclerotic lesions in human ex vivo coronary arteries

In the present study, we tested the ability of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI) to identify and retrospectively characterize atherosclerotic lesions in human ex vivo coronary arteries. Thirteen ex vivo hearts were studied with MDCT and MRI. MDCT-images were obtained with an isotropic voxel size of 0.6mm(3). MR images were obtained with an in-plane resolution of 195 microm and 3mm slice thickness. All images were matched with histopathology sections. For both modalities, the sensitivity for the detection of any atherosclerotic lesion was evaluated, and a retrospective analysis of plaque morphology according to criteria defined by the American Heart Association (AHA) was performed. At histopathology, 28 atherosclerotic lesions were found. 21 and 23 of these lesions were identified by MDCT and MRI, respectively. Both modalities detected a small number of false-positive lesions. After retrospective matching with histopathology, MDCT as well as MRI were able to differentiate typical morpholocigal features for fatty, fibrous or calcified plaque components. Using the information presented in this study, in vivo coronary artery wall imaging using MDCT as well as MRI could be facilitated and supported for future investigations on this subject.

Magnetic resonance imaging and computed tomography in assessment of atherosclerotic plaque

The two most promising noninvasive imaging modalities for the study of atherosclerosis are magnetic resonance imaging (MRI) and computed tomography (CT). Both have been shown to be capable of imaging vessel wall structures and differentiating various stages of atherosclerotic wall changes. MRI has been applied in various in vivo human studies to image atherosclerotic plaques in coronary arteries, carotid arteries, and aorta. The latest generation of multidetector row computed tomography (MDCT) systems allows for the noninvasive characterization of different plaque components in various vascular structures. MDCT allows evaluation of the whole arterial vasculature. In addition, MDCT has the ability to visualize the vessel wall and to give a quantitative measurement of calcified and noncalcified plaque. Using either technique, the repeatable, noninvasive study of atherosclerotic disease during its natural history and after therapeutic intervention will enhance our understanding of disease progression and regression. MDCT and MRI, therefore, may help in selecting appropriate treatments.

CT of coronary artery disease

The socioeconomic importance of heart disease provides considerable motivation for development of radiologic tools for noninvasive imaging of the coronary arteries. Current computed tomographic (CT) techniques combine high speed and spatial resolution with sophisticated electrocardiographic synchronization and robustness of use. Application of these modalities for evaluation of coronary artery disease is a topic of active current research. Coronary artery calcium measurements with different CT techniques have been used for determining the risk of coronary events, but the exact role of this marker for cardiac risk stratification remains unclear pending results of population-based studies. Contrast material-enhanced CT coronary angiography has become an established clinical indication for some scenarios (eg, coronary artery anomalies, bypass patency, surgical planning). With current technology, the accuracy of CT coronary angiography for detection of coronary artery stenoses appears promising enough to warrant pursuit of this application, but sensitivity is still not high enough for routine diagnostic needs. The high negative predictive value of a normal CT coronary angiogram, however, may be useful for reliable exclusion of coronary artery stenosis. The cross-sectional nature of CT may allow noninvasive assessment of the coronary artery wall. Use of contrast-enhanced CT coronary angiography for detection, characterization, and quantification of atherosclerotic changes and total disease burden in coronary arteries as a potential tool for cardiac risk stratification is currently being investigated.

Coronary Artery Calcium Scoring Using 16-MDCT and a Retrospective ECG-Gating Reconstruction Algorithm

OBJECTIVE

Our aim was to compare detection, quantification, and cardiovascular risk stratification of coronary artery calcium (CAC) between electron beam CT and 16-MDCT with retrospective reconstruction. SUBJECTS AND METHODS. One hundred patients underwent both electron beam CT and 16-MDCT, and coronary artery calcium score, volume, and mass were obtained.

RESULTS

Correlation between the two CT scanners was high for both calcium score (r(2) = 0.955), volume (r(2) = 0.952), and mass (r(2) = 0.977). Although electron beam CT is viewed as the gold standard, the sensitivity and specificity in the detection of CAC using 16-MDCT with a threshold of 130 H were 98.7% and 100%, respectively. The variability of calcium scores between the two CT scanners (26.5%) was comparable with two electron beam CT scanners reported previously. The variability of calcium volume (20.7%) and mass (20.3%) was lower than that of the score (Student's t test, r = 0.05, 0.01). In clinical cardiovascular risk stratification based on two CT calcium scores, the Cohen's kappa value was 0.929. There was no significant difference between the two scanners using Wilcoxon's signed rank test (p = 0.157).

CONCLUSION

The 16-MDCT scanner with retrospective reconstruction, showing high agreement for detection and quantification of CAC with electron beam CT, holds promise in the detection of coronary artery atherosclerosis.

Coronary artery calcium quantification at multi-detector row helical CT versus electron-beam CT

PURPOSE

To compare coronary artery calcium scores from a multi-detector row helical computed tomographic (CT) scanner with those from an electron-beam CT scanner, with emphasis on subjects with calcium scores less than 400.

MATERIALS AND METHODS

Seventy-eight asymptomatic subjects (37 women, 41 men; age range, 39-78 years; mean age, 54.2 years) underwent multi-detector row CT and electron-beam CT. Volume and Agatston scores were calculated with a workstation. Statistical analyses included assessment of association between calcium scores from two scanners, calculation of percent absolute difference to assess score variability between scanners, equivalence analysis, construction of Bland-Altman plots to assess agreement between scores, and assessment of changes in score grouping and risk criteria based on score differences between scanners.

RESULTS

Electron-beam CT calcium scores were higher than multi-detector row CT scores. Linear association between calcium scores obtained from paired scans was significant (r = 0.96-0.99, P <.001). Mean percent absolute differences were 67.9% and 65.0% for volume and Agatston scores, respectively (48.6% and 46.3% for corresponding natural log-transformed scores). In subjects with a score of 11 or greater, mean percent absolute differences between electron-beam CT and multi-detector row CT scores ranged from 15% to 30% (<10% for natural log-transformed calcium scores). With a 20% equivalence limit, calcium scores from the two scanners were statistically equivalent (P <.05). Score grouping would have been subject to change in 12 (11 increased and one decreased; six with scores of 11 or greater), and possible risk management decisions would have been subject to change in eight (16%) of 51 subjects who underwent electron-beam CT versus multi-detector row CT scanning.

CONCLUSION

Multi-detector row CT appears to be comparable to electron-beam CT for coronary calcification screening, except in subjects with a calcium score less than 11.

Comparison of ability to identify left atrial thrombus by three-dimensional tomography versus transesophageal echocardiography in patients with atrial fibrillation

We sought to determine the potential use of recently introduced cardiac 3-dimensional computed tomography as an alternative to transesophageal echocardiography for examination of the left atrial appendage. Our data suggest that computed tomography is a potential alternative for assessing the anatomy of the left atrial appendage and for detecting thrombi.

Electron beam CT versus helical CT scans for assessing coronary calcification: current utility and future directions

BACKGROUND

Traditional risk factors for coronary artery disease predict the development of atherosclerosis; however, their ability to identify individual patients at risk of events is limited.

METHODS

Coronary artery calcium (CAC) is a specific marker of atherosclerosis. It can be visualized and measured noninvasively by various imaging techniques, which may add incremental prognostic value to conventional coronary factors.

RESULTS

The field of atherosclerosis imaging has expanded rapidly in the last decade, and technologies such as electron-beam computed tomography (EBCT) have contributed to our understanding of the prevalence of occult coronary artery disease and its consequences. Other modalities have been previously limited by the decreased temporal and spatial resolution and slower acquisition. Recent advances in helical CT (HCT) imaging with the development of multiple row detectors CT (MDCT) and improvements in the temporal resolution have renewed clinicians' interests in using this modality to evaluate CAC, although the scores obtained with MDCT may differ somewhat from those obtained with the EBCT technology. This study critically analyzes the literature comparing the utility of EBCT and HCT in detecting coronary calcium to identify individuals at increased risk for future coronary events.

CONCLUSIONS

MDCT is a promising tool for coronary calcium scoring; however, more studies are needed comparing EBCT and MDCT, especially at lower CAC levels.

Coronary Artery Calcification Scoring by Prospectively Triggered Multidetector-Row Computed Tomography

The objective of this study was to measure the interobserver and interscan variation of coronary artery calcium scores using multidetector-row computed tomography (MDCT). Seventy-five patients underwent 2 sequential MDCT scans for coronary artery calcification. Each patient's score was separately measured by 3-blinded radiologists. Scores were treated as discrete and continuous data, and independent statistical analysis was performed on all results. There was a high proportion of interscan and inter-reader concordance for the presence of coronary calcium (range, 0.893-0.973) and for its quantity (range, 0.936-0.988). Overall, prospectively triggered multidetector-row calcium scoring is reproducible though there is more variation in those patients with already high scores. There is no need to scan patients twice at the same sitting.

Imaging of coronary calcification by computed tomography

As an unequivocal biomarker for arteriosclerosis, the presence of coronary calcium serves as a qualitative reflection of the severity of coronary artery disease (CAD). Greater calcium burdens correlate with more advanced disease, a higher likelihood of coronary stenoses, and a higher risk for coronary heart disease (CHD). Empirically, the quantification of coronary calcium not only provides an accurate reflection of disease severity, but also has great potential as a screening tool for CHD. Computed tomography (CT) has been shown to be capable of providing accurate, noninvasive measurements of coronary calcification. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that calcium burdens accurately reflect disease severity and can be used to assess individual risk for CHD. The purpose of this review article is to examine the accumulated evidence that has attempted to validate CT as a diagnostic tool for CAD and as a screening exam for CHD.

Past, present, and future perspective of cardiac computed tomography

In the United States, more than 1 million diagnostic invasive coronary angiograms are performed annually, and in about 50% the investigation is followed by an interventional procedure. The remaining symptomatic patients after angiography are treated conservatively or by bypass graft surgery. In recent decades coronary angiography has advanced to a fast and safe investigation. Nevertheless, in particular, patients are well aware of the small but not negligible risk of complications and the discomfort of the invasive procedure. In addition to electrocardiogram (EKG) or ultrasound stress test and thallium scintigraphy, there is further need for another noninvasive method that displays the morphology of the coronary arteries in a way that would allow the triage of patients with suspicion of coronary artery disease (CAD) for a conservative, interventional, or surgical treatment.