The effect of aortic area measurement site on the energy loss coefficient: a comparison between echocardiography and cardiac computed tomography angiography in patients with aortic stenosis.

AIM: The energy loss coefficient (ELCo) has been suggested as a more accurate indicator of aortic stenosis (AS) severity as compared to transthoracic echocardiography (TTE) aortic valve area (AVA). There are little data regarding the optimal location for aortic area (Aa) measurement needed for ELCo calculation and the agreement of ELCo with direct anatomical AVA measurement. The aim of this study was to determine the optimal site of Aa measurement for calculation of the ELCo, using cardiac computed tomography angiography (CCTA) AVA planimetry as the reference standard. METHODS: We analyzed 69 patients with AS who underwent both CCTA and TTE. ELCo and CCTA planimetry AVA were compared using multiple sites for CCTA Aa measurement (sinus, sinotubular junction, or ascending aorta). RESULTS: CCTA AVA was 0.96±0.46 cm2 . ELCo was 0.95±0.43 cm2 using sinotubular junction Aa, 0.92±0.41 cm2 using sinus Aa, and 0.91±0.4 cm2 using the ascending aorta (P=.84, P=.13, and P=.08 compared to CCTA AVA). There was good agreement between CCTA AVA and ELCo using all Aa locations (0.89-0.90). On subgroup analysis of 16 patients most likely to be affected by pressure recovery (aortic diameter<3 cm and AVA ≥1 cm2 ), ELCo using the sinotubular junction Aa showed the best agreement with CCTA AVA as compared to the other Aa locations (0.84 vs 0.75-0.77). CONCLUSIONS: ELCo using Aa measurement at the sinotubular junction showed the best agreement with CCTA AVA. We therefore recommend using the sinotubular junction Aa for ELCo calculation.

[Appropriateness criteria for the use of cardiac computed tomography: position paper of the Israeli Heart Society and the Israeli Society of Radiology].

Cardiac computed tomography (CCT) is a relatively new imaging modality which allows high quality imaging of the coronary vessels and various cardiac structures. Together with the advances in scanner technology and the more frequent use of the technology in clinical practice, there is a need to better define the appropriate indications for the use of CCT. This review summarizes the appropriateness criteria for the use of CCT as were defined by a joint committee of the Israeli Heart Society and the Israeli Society of Radiology.

Value of multidetector computed tomography evaluation of myocardial perfusion in the assessment of ischemic heart disease: comparison with nuclear perfusion imaging.

MDCT-derived myocardial perfusion has not yet been validated against accepted standards. We developed a technique for quantification of myocardial perfusion from MDCT images and studied its diagnostic value against SPECT myocardial perfusion imaging (MPI). Ninety-eight patients were studied. Abnormal perfusion was detected by comparing normalized segmental x-ray attenuation against values obtained in 20 control subjects. Disagreement with resting MPI was investigated in relationship to MDCT image quality, severity of MPI abnormalities, and stress MPI findings. Resting MPI detected mild or worse abnormalities in 20/78 patients. MDCT detected abnormalities in 15/20 patients (sensitivity of 0.75). Most abnormalities missed by MDCT analysis were graded as mild on MPI. Additional abnormalities found in 16/78 patients were not confirmed on resting MPI (specificity of 0.72). However, 8 of these 16 apparently false positive MDCT perfusion tests had abnormal stress MPI; of these 8 patients, 7 had optimal MDCT image quality, while in 6/8 remaining patients, image quality was suboptimal. When compared with resting MPI, MDCT detected perfusion abnormalities with high accuracy. Moreover, half of MDCT perfusion abnormalities not confirmed by resting MPI were associated with abnormal stress MPI. Importantly, this information can be obtained without additional radiation dose or contrast agent.

Usefulness of 64-slice cardiac computed tomographic angiography for diagnosing acute coronary syndromes and predicting clinical outcome in emergency department patients with chest pain of uncertain origin.

BACKGROUND: Multidetector computed tomography (MDCT) has high diagnostic value for detecting or excluding coronary artery stenosis. We examined performance characteristics of MDCT for diagnosing or excluding an acute coronary syndrome in patients presenting to the emergency department (ED) with possible ischemic chest pain and examined relation to clinical outcome during a 15-month follow-up period. METHODS AND RESULTS: We prospectively studied 58 patients (56+/-10 years of age, 36% female) with chest pain possibly ischemic in origin and no new ECG changes or elevated biomarkers. The patients underwent 64-slice contrast-enhanced MDCT, which showed normal coronary vessels (no or trivial atheroma) in 15 patients, nonobstructive plaque in 20 (MDCT-negative patients), and obstructive coronary disease (> or = 50% luminal narrowing) in 23 (MDCT-positive group). By further investigation (new elevation of cardiac biomarkers, abnormal myocardial perfusion scintigraphy and/or invasive angiography), acute coronary syndrome was diagnosed in 20 of the 23 MDCT-positive patients (ED MDCT sensitivity 100% [20/20], specificity 92% [35/38], positive predictive value 87% [20/23], negative predictive value 100% [35/35]). During a 15-month follow-up period, no deaths or myocardial infarctions occurred in the 35 patients discharged from the ED after initial triage and MDCT findings. One patient underwent late percutaneous coronary intervention (late major adverse cardiovascular events rate, 2.8%). Overall, ED MDCT sensitivity for predicting major adverse cardiovascular events (death, myocardial infarction, or revascularization) during hospitalization and follow-up was 92% (12/13), specificity was 76% (34/45), positive predictive value was 52% (12/23), and negative predictive value was 97% (34/35). CONCLUSIONS: We found that 64-slice cardiac MDCT is a potentially valuable diagnostic tool in ED patients with chest pain of uncertain origin, providing early direct noninvasive visualization of coronary anatomy. ED MDCT had high positive predictive value for diagnosing acute coronary syndrome, whereas a negative MDCT study predicted a low rate of major adverse cardiovascular events and favorable outcome during follow-up.

Current status and clinical applications of cardiac multidetector computed tomography.

Contrast-enhanced multidetector-row computed tomography (MDCT) is now capable of providing high-quality noninvasive views of cardiac anatomy and 'instant' noninvasive coronary angiography. With current generation 64-slice scanners, MDCT can be performed in most patients with minimal patient discomfort and high diagnostic accuracy. MDCT may obviate the need for invasive diagnostic angiography in patients with borderline symptoms or equivocal noninvasive testing. It is useful in assessing the symptomatic patient postrevascularization and in emergency room triage in selected patients with chest pain. Calcified vessels are still difficult to assess, as is the accurate evaluation of implanted coronary stents. The volume of contrast material required for proper opacification limits the use of MDCT in patients with renal dysfunction, but newer emerging technologies will greatly improve these disadvantages in the near future. MDCT is expected to become an integral part of our diagnostic armamentarium in the cardiac patient.

Prevalence and extent of obstructive coronary artery disease in patients with zero or low calcium score undergoing 64-slice cardiac multidetector computed tomography for evaluation of a chest pain syndrome.

We examined the extent of coronary artery disease (CAD) on 64-slice contrast-enhanced multidetector computed tomography in patients who underwent investigation of a chest pain syndrome who had a zero or low coronary calcium score (CS). In 668 consecutive patients with chest pain syndromes (39% with acute presentation, 61% with long-term presentation) who underwent cardiac multidetector computed tomography, we assessed prevalence and severity of coronary stenoses (>or=1 coronary artery stenosis with >or=50% luminal narrowing) in 231 patients (54 +/- 12 years of age, 45% women) with a 0 (n = 125) or low (n = 106) coronary CS. Obstructive (>or=50% lesion) CAD was present in 27 of 231 patients, in 9 of 125 patients (7%) with a 0 CS, in 18 of 106 (17%) with a low CS (1 to 100), and in 14 of 90 patients (16%) with an acute presentation and 13 of 141 patients (9%) with a long-term presentation (p = NS). All patients in the 0 CS group had single-vessel disease, and 9 (50%) with low CS had multivessel disease, with left main involvement in 1. Of the 27 patients with obstructive CAD on multidetector computed tomography, invasive coronary angiography confirmed these findings in 21 of 23 patients (positive predictive value 91%), and 16 (76%) of them (6.9% of the 0 CS and low CS groups) underwent a myocardial revascularization procedure after invasive coronary angiographic concordance. In conclusion, despite the high known negative predictive value of CS for coronary events, a low and even 0 CS does not exclude clinically important obstructive CAD in patients undergoing investigation of an acute or long-term chest pain syndrome. Contrast-enhanced multidetector computed tomography should be the noninvasive computed tomographic test of choice when possible in these patients.

Impact of 64-slice cardiac computed tomographic angiography on clinical decision-making in emergency department patients with chest pain of possible myocardial ischemic origin.

To examine the impact of contrast enhanced multidetector computed tomography (MDCT) on clinical decision-making in patients who present to the emergency department (ED) with chest pain of possible ischemic origin, we studied 58 consecutive patients (age 56 +/- 10 years, 36% female) with chest pain, intermediate risk, and no ischemic electrocardiographic changes or increased biomarker measurements. After standard ED patient assessment including cardiology consultation, a diagnosis of acute coronary syndrome was made in 41 patients (71%), hospitalization was recommended in 47 (81%), and 32 (55%) were scheduled for an early invasive strategy. Patients underwent 64-slice contrast agent-enhanced MDCT with image reconstruction in multiple formats using retrospective electrocardiographic gating, which revealed normal (no or trivial atheroma) coronary vasculature in 15 patients, nonobstructive atheroma in 20 patients, and obstructive coronary disease (> or =1 luminal narrowing of > or =50%) in 23 patients. After MDCT, the diagnosis of acute coronary syndrome was revised in 18 of 41 patients (44%; 16 normal MDCT/widely patent stents, 2 alternative diagnoses), planned hospitalization canceled in 21 of 47 patients (45%; 13 normal MDCT/patent stent, 8 minor branch vessel disease), and planned early invasive strategy altered in 25 of 58 patients (43%; unnecessary in 20 of 32, advisable in 5 of 26 others). Effect of MDCT on clinical decisions was greater in the 36 patients without known preceding coronary disease. In 32 patients discharged from the ED (11 after initial triage, 21 patients after MDCT), there were no major adverse cardiac events (e.g., death, myocardial infarction, unplanned revascularization) during a 12-month follow-up period. In conclusion, contrast agent-enhanced 64-slice cardiac MDCT was a valuable diagnostic tool in the ED triage of patients with chest pain of possible ischemic origin and decreased the need for hospitalization by almost half in this patient cohort.

Usefulness of 64-slice multidetector computed tomography in diagnostic triage of patients with chest pain and negative or nondiagnostic exercise treadmill test result.

The usefulness of 64-slice multidetector coronary computed tomography (MDCT) in a diagnostic triage of 100 consecutive patients (age 55.8+/-11.6 years; 57% men) with chest pain suspected to be ischemic in origin and a negative or nondiagnostic exercise treadmill test (ETT) result was examined. None of the patients had previously known coronary artery disease (CAD). MDCT showed obstructive (>or=50%) CAD in 29 patients; 13 of 59 patients (22%) with a negative and 16 of 41 patients (39%) with a nondiagnostic ETT result. High-risk (left main and/or 3-vessel) CAD was present in 3.3% of patients with a negative and 4.9% with a nondiagnostic ETT result. The 29 patients with obstructive CAD on MDCT had a higher mean Agatston calcium score (221+/-402 vs 40+/-77 U, p<0.001). Invasive coronary angiography confirmed MDCT findings in 26 of 29 patients (positive predictive value 90%) and 45 of 54 stenotic segments (83%) in a per-segment analysis. For the 71 patients without obstructive CAD on MDCT, clinically driven invasive angiography detected CAD in 1 of 15 patients (1 false-negative MDCT result) and 2 of another 5 patients who were referred for invasive angiography later during a 12-month follow-up period. In the remaining 51 patients, MDCT findings effectively allowed exclusion of obstructive CAD, and there were no major adverse clinical events during follow-up. In conclusion, in patients with chest pain possibly ischemic in origin, no previously known CAD, and a negative or nondiagnostic ETT result, contrast-enhanced 64-slice MDCT scanning was a useful tool to provide direct noninvasive coronary angiography and rapidly advance diagnostic triage.

Uses and limitations of 40 slice multi-detector row spiral computed tomography for diagnosing coronary lesions in unselected patients referred for routine invasive coronary angiography.

BACKGROUND AND AIMS: The value of multi-detector row computed tomography (MDCT) in routine cardiology practice is uncertain. We examined the applicability of MDCT imaging for the diagnosis of obstructive coronary artery disease in a routine clinical setting. METHODS: MDCT scanning (40 slice) was performed in 111 unselected patients referred for invasive coronary angiography (ICA) and findings were compared to an independent quantitative assessment of the ICA on a segmental, vessel and patient basis. RESULTS: Sensitivity and positive predictive value for segmental disease (72.2 and 70.9% respectively, overall) were higher in patients aged > or = 60 years and history of disease > or = 1 year, whereas specificity and negative predictive value were high in all groups. In the patient-based analysis, sensitivity and positive predictive value (84.7 and 87.8%, respectively) were higher, the latter in keeping with the high-patient prevalence of disease, but specificity and negative predictive value (61.5 and 55.2%) were low. CONCLUSIONS: Usefulness of MDCT was significantly influenced by age, duration of coronary artery disease and female gender, and on a patient-based analysis its diagnostic accuracy was not sufficient to replace ICA in a routine clinical setting.

Advantages of multidetector computed tomography angiography in the evaluation of patients with chest pain.

Noninvasive imaging of the coronary arteries using multidetector computed tomography is gaining recognition among clinicians. The rapid evolution of this technology is opening new frontiers in the diagnosis of coronary artery disease. This article reviews the current status and future potential for the application of noninvasive coronary multidetector computed tomography angiography in the assessment of coronary artery stenosis, coronary artery anomalies, mural plaque and coronary stent and bypass graft patency.

Initial experience with a cardiologist-based chest pain unit in an emergency department in Israel.

BACKGROUND: Emergency room triage of patients presenting with chest pain syndromes may be difficult. Under-diagnosis may be dangerous, while over-diagnosis may be costly. OBJECTIVES: To report our initial experience with an emergency room cardiologist-based chest pain unit in Israel. METHODS: During a 5 week pilot study, we examined resource utilization and ER diagnosis in 124 patients with chest pain of uncertain etiology or non-high risk acute coronary syndrome. First assessment was performed by the ER physicians and was followed by a second assessment by the CPU team. Assessment was based on the following parameters: medical history and examination, serial electrocardiography, hematology, biochemistry and biomarkers for ACS, exercise stress testing and/or 64-slice multi-detector cardiac computed tomography angiography. Changes in decision between initial assessment and final CPU assessment with regard to hospitalization and utilization of resources were recorded. RESULTS: All patients had at least two cardiac troponin T measurements, 19 underwent EST, 9 echocardiography and 29 cardiac MDCT. Fourteen patients were referred for early cardiac catheterization (same/next day). A specific working diagnosis was reached in 71/84 patients hospitalized, including unstable angina in 39 (31%) and non-ST elevation myocardial infarction in 12 (10%). Following CPU assessment, 40/124 patients (32%) were discharged, 49 (39%) were admitted to Internal Medicine and 35 (28%) to the Cardiology departments. CPU assessment and extended resources allowed discharge of 30/101 patients (30%) who were initially identified as candidates for hospitalization after ER assessment. Furthermore, 13/23 patients (56%) who were candidates for discharge after initial ER assessment were eventually hospitalized. Use of non-invasive tests was significantly greater in patients discharged from the ER (85% vs. 38% patients hospitalized) (P < 0.0001). The mean ER stay tended to be longer (14.9 +/- 8.6 hours vs. 12.9 +/- 11, P = NS) for patients discharged. At 30 days follow-up, there were no adverse events (myocardial infarction or death) in any of the 40 patients discharged from the ER after CPU assessment. One patient returned to the ER because of chest pain and was discharged after reassessment. CONCLUSIONS: Our initial experience showed that an ER cardiologist-based chest pain unit improved assessment of patients presenting to the ER with chest pain, and enhanced appropriate use of diagnostic tests prior to a decision regarding admission/discharge from the ER.

Validation of remote dielectric sensing (ReDS™) technology for quantification of lung fluid status: Comparison to high resolution chest computed tomography in patients with and without acute heart failure.

BACKGROUND: Pulmonary congestion is a common presentation of acute decompensated heart failure (ADHF). The ability to quantify increased pulmonary parenchymal water content in chest computed tomography (CCT) is well known. However, availability and radiation limitations make it unsuitable for serial assessment of lung fluid content. The ReDS™ technology allows quantification of lung fluid content. OBJECTIVE: The objective of this work was to validate the ability of the ReDS™ technology to quantify total lung fluid when compared with CCT in ADHF and non-ADHF patients. METHODS: Following CCT, ReDS measurements were obtained from consented subjects. ReDS measurements were then compared to the CCT using lung density analysis software. CCT results were converted from Hounsfield Units to percentage units, allowing comparison with the ReDS readings. The analyses, performed on 16 ADHF and 15 non-ADHF patients, were conducted by an independent observer blinded to ReDS outcomes. RESULTS: The fluid content averages and standard deviations for the non-ADHF group were 28.7±5.9% and 27.3±6.6% and for the ADHF patients 40.7±8.8% and 39.8±6.8% (CCT and ReDS respectively). Intraclass correlation was found to be 0.90, 95% CI [0.8-0.95]. Regression analysis yielded a slope of 0.94 (95% confidence interval [0.77-1.12]) and intercept 3.10 (95% confidence interval of [-3.02-9.21]). The absolute mean difference between the quantification of the two methods was 3.75 [%] with SD of 2.22 [%]. CONCLUSION: Current findings show high correlation between the ReDS noninvasive system and CCT in both ADHF and non-ADHF patients. Remote patient monitoring using ReDS™ based system may help in the management of patients with heart failure.

The role of 16-slice computed tomography angiography in the diagnosis of coronary artery disease: large sample analysis.

BACKGROUND: Computed tomography angiography enables non-invasive evaluation of the coronary arteries. OBJECTIVES: To evaluate the accuracy of 16-slice multi-detector CT angiography in the diagnosis of coronary artery disease, and assess coronary bypass grafts and coronary anomalies. METHODS: We conducted a retrospective study of 223 patients who were examined at our medical center over a period of 2 years with a 16-slice CT angiography scanner and retrospective electrocardiographic gating. RESULTS: There were no significant complications, and good visualization of the coronary arteries was achieved in all but eight patients. A high correlation with the results of the invasive angiography was noted (sensitivity 85%, specificity 93%, negative predictive value 98%). Altogether, 131 bypass conduits were examined with excellent graft visualization, Several coronary anomalies were detected, as were significant extra-cardiac findings. CONCLUSIONS: Multi-slice CT angiography is a reliable noninvasive diagnostic procedure for demonstration of the coronary arteries and bypass grafts. In the future it will probably replace part of the diagnostic invasive coronary angiography and, as a result, a large proportion of coronary angiography procedures will be therapeutic.

Low cardiorespiratory fitness and coronary artery calcification: Complementary cardiovascular risk predictors in asymptomatic type 2 diabetics.

BACKGROUND: Despite its well-established prognostic value, cardiorespiratory fitness (CRF) is not incorporated routinely in risk assessment tools. Whether low CRF provides additional predictive information in asymptomatic type 2 diabetics beyond conventional risk scores and coronary artery calcification (CAC) is unclear. METHODS: We studied 600 type 2 diabetics aged 55-74 years without known coronary heart disease. CRF was quantified in metabolic equivalents (METs) by maximal treadmill testing and categorized as tertiles of percent predicted METs (ppMETs) achieved. CAC was calculated by non-enhanced computed tomography scans. The individual and joint association of both measures with an outcome event of all-cause mortality, myocardial infarction or stroke, was determined over a mean follow-up period of 80 ± 16 months. RESULTS: There were 72 (12%) events during follow-up. Low CRF was independently associated with event risk after adjustment for traditional risk factors and CAC (HR 2.25, 95% CI 1.41-3.57, p = 0.001). CRF (unfit/fit) allowed further outcome discrimination both amongst diabetics with low CAC scores (9.5% versus 2.0% event rate), and amongst diabetics with high CAC scores (23.5% versus 12.4% event rate), p < 0.001. The addition of CRF to a model comprising UKPDS and CAC scores improved the area under the curve for event prediction from 0.66 to 0.71, p = 0.03, with a positive continuous net reclassification improvement (NRI) of 0.451, p = 0.002. CONCLUSIONS: CRF, quantified by ppMETs, provided independent prognostic information which was additive to CAC. Low CRF may identify asymptomatic diabetic subjects at higher risk for all-cause mortality, myocardial infarction or stroke, despite low CAC.

Prognostic impact of abdominal fat distribution and cardiorespiratory fitness in asymptomatic type 2 diabetics.

BACKGROUND: Impaired cardiorespiratory fitness (CRF) is a potent risk factor for mortality in diabetes, and may modify the relation between adiposity and mortality. We evaluated the interaction between CRF and abdominal adiposity distribution with all-cause mortality, myocardial infarction or stroke in patients with diabetes. METHODS: We studied 294 type 2 diabetics without known coronary artery disease. CRF was quantified in metabolic equivalents by maximal treadmill testing, and categorized as low CRF (first tertile) or high CRF (second and third tertiles). Abdominal fat was quantified as subcutaneous or visceral adipose tissue from non-enhanced computed tomography scans. Association of CRF, adiposity distribution and their interaction with all-cause mortality, myocardial infarction or stroke was assessed by Cox proportional-hazard models. RESULTS: There were 31 (11%) events during 62 ± 12 months. Low CRF was significantly associated with event risk before and after adjustment for each measure of adiposity (hazard ratio 3.79, 95% confidence interval 1.79-8.01, p < 0.001). CRF level was inversely correlated with subcutaneous (r = -0.44, p < 0.001) but not visceral adipose tissue (r = -0.06, p = 0.31). Absolute event rates increased progressively across visceral adipose tissue tertiles, but decreased across subcutaneous tertiles. However, within each tertile of both adiposity measures, increased events were observed in the low compared with the high CRF group; this trend was also observed in an adjusted multivariate proportional hazards model. CONCLUSIONS: Although subcutaneous and visceral adipose tissues differed in their association with CRF levels and absolute event rates, lower baseline CRF in type 2 diabetics was significantly associated with higher risk of all-cause mortality, myocardial infarction or stroke, regardless of abdominal adiposity pattern.

Automated Computer-Assisted Diagnosis of Obstructive Coronary Artery Disease in Emergency Department Patients Undergoing 256-Slice Coronary Computed Tomography Angiography for Acute Chest Pain.

A 256-slice coronary computed tomography angiography (CCTA) is an accurate method for detection and exclusion of obstructive coronary artery disease (OBS-CAD). However, accurate image interpretation requires expertise and may not be available at all hours. The purpose of this study was to evaluate the usefulness of a fully automated computer-assisted diagnosis (COMP-DIAG) tool for exclusion of OBS-CAD in patients in the emergency department (ED) presenting with chest pain. Three hundred sixty-nine patients in ED without known coronary disease underwent 256-slice CCTA as part of the assessment of chest pain of uncertain origin. COMP-DIAG (CorAnalyzer II) automatically reported presence or exclusion of OBS-CAD (>50% stenosis, ≥1 vessel). Performance characteristics of COMP-DIAG for exclusion and detection of OBS-CAD were determined using expert reading as the reference standard. Seventeen (5%) studies were unassessable by COMP-DIAG software, and 352 patients (1,056 vessels) were therefore available for analysis. COMP-DIAG identified 33% of assessable studies as having OBS-CAD, but the prevalence of OBS-CAD on CCTA was only 18% (66 of 352 patients) by standard expert reading. However, COMP-DIAG correctly identified 61 of the 66 patients (93%) with OBS-CAD with 21 vessels (2%) with OBS-CAD misclassified as negative. In conclusion, compared to expert reading, automated computer-assisted diagnosis using the CorAnalyzer showed high sensitivity but only moderate specificity for detection of obstructive coronary disease in patients in ED who underwent 256-slice CCTA. The high negative predictive value of this computer-assisted algorithm may be useful in the ED setting.

Noninvasive evaluation of arterial grafts with newly released multidetector computed tomography.

BACKGROUND: High-quality postoperative imaging of bypass conduits is essential when evaluating different types of conduits, anastomoses, and surgical techniques. We investigated the potential value of the newest generation of multidetector-row computer tomographic scanners in assessing bypass grafts. METHODS: From June to September 2002, 14 patients underwent scanning with a newly released 16-slice computed tomographic scanner (Mx8000 IDT; Philips Medical Systems) after coronary artery bypass grafting. Four patients had had minimally invasive direct coronary artery bypass grafting and 3, redo coronary artery revascularization. Contrast-enhanced computed tomographic angiography was performed using retrospective electrocardiographic gating. Scan length was 22 to 30 cm, and total scan time was 27 to 37 seconds. RESULTS: Of the 14 patients, 8 were scanned within 1 week after operation and 6, 1 month to 12 months postoperatively. Average heart rate during the scan was 82 beats per minute (range, 60 to 97 beats per minute), and all patients were able to hold their breath for the required time. Thirty conduits were studied: 26 arterial (18 in situ left and right internal mammary artery grafts, five free right internal mammary and radial artery grafts, and three in situ right gastroepiploic artery grafts) and four vein grafts. Excellent visualization of all 30 grafts was achieved. Thirty-four of the 35 distal anastomoses were patent; one vein graft was occluded. CONCLUSIONS: This new technology is a promising noninvasive measure to evaluate patency of bypass conduits, including the gastroepiploic artery where catheterization is usually difficult. The ability to display the vessel wall as well as its lumen might distinguish radial artery spasm from intimal hyperplasia. The superb resolution and increased scan length required to cover the entire internal mammary artery grafts-from origin to distal anastomoses-can be achieved easily in a single breath-holding owing to the increased number of slices per rotation and shortening of the gantry rotation time.