Perfusion findings in (13)N-ammonia PET and CFR are strong outcome predictors. CFR allows further risk stratification, suggesting a "warranty" period of 3 years if normal CFR is associated with normal perfusion. Conversely, in patients with abnormal perfusion, an impaired CFR has added value for predicting adverse outcomes.

This first experience documents the feasibility of prospective ECG-gating for CTCA with diagnostic image quality at a low radiation dose (1.1-3.0 mSv), favouring HR <63 b.p.m.

The aim of this study was to assess the diagnostic accuracy of dualsource computed tomography (DSCT) for evaluation of coronary artery disease (CAD) in a population with extensive coronary calcifications without heart rate control. Thirty patients (24 male, 6 female, mean age 63.1±11.3 years) with a high pre-test probability of CAD underwent DSCT coronary angiography and invasive coronary angiography (ICA) within 14 ± 9 days. No beta-blockers were administered prior to the scan. Two readers independently assessed image quality of all coronary segments with a diameter ≥1.5 mm using a four-point score (1: excellent to 4: not assessable) and qualitatively assessed significant stenoses as narrowing of the luminal diameter >50%. Causes of false-positive (FP) and false-negative (FN) ratings were assigned to calcifications or motion artifacts. ICA was considered the standard of reference. Mean body mass index was 28.3 ± 3.9 kg/m 2 (range 22.4-36.3 kg/m 2 ), mean heart rate during CT was 70.3 ± 14.2 bpm (range 47-102 bpm), and mean Agatston score was 821 ± 904 (range 0-3,110). Image quality was diagnostic (scores 1-3) in 98.6% (414/420) of segments (mean image quality score 1.68 ± 0.75); six segments in three patients were considered not assessable (1.4%). DSCT correctly identified 54 of 56 significant coronary stenoses. Severe calcifications accounted for false ratings in nine segments (eight FP/one FN) and motion artifacts in two segments (one FP/one FN). Overall sensitivity, specificity, positive and negative predictive value for evaluating CAD were 96.4, 97.5, 85.7, and 99.4%, respectively. First experience indicates that DSCT coronary angiography provides high diagnostic accuracy for assessment of CAD in a high pre-test probability population with extensive coronary calcifications and without heart rate control.

Coronary angiography with 64-section CT provides diagnostic image quality within a wide range of heart rates. Reducing average heart rate and heart rate variability is beneficial for reducing artifacts.

This study had institutional review board approval; written informed consent was obtained. The purpose was to prospectively determine the heart rate (HR) dependency of three-dimensional (3D) coronary artery motion by incorporating into analysis the durations of systole and diastole. Thirty patients (seven women, 23 men; mean age, 56.6 years +/- 12.7 [standard deviation]; HR: 45-100 beats per minute) underwent electrocardiographically gated 64-section computed tomographic (CT) coronary angiography to determine coronary motion velocities at bifurcation points. Significance of velocity differences (P < .05) was determined by using analysis of variance for repeated measures and Bonferroni post hoc tests. HR dependency was determined by using linear regression analysis. HR significantly affected 3D coronary motion (r = 0.47, P < .009) through nonproportional shortening of systole and diastole (r = -0.82, P < .001), leading to percentage reconstruction interval shifts of coronary velocity troughs and peaks (P < .01). Results suggest that image reconstruction algorithms at CT coronary angiography be adapted to the individual patient's HR.

We aimed at establishing the optimal scan time for nuclear myocardial perfusion imaging (MPI) on an ultrafast cardiac g-camera using a novel cadmium-zinc-telluride (CZT) solid-state detector technology. Methods: Twenty patients (17 male; BMI range, 21.7-35.5 kg/m 2 ) underwent 1-d 99m Tc-tetrofosmin adenosine stress and rest MPI protocols, each with a 15-min acquisition on a standard dual-detector SPECT camera. All scans were immediately repeated on an ultrafast CZT camera over a 6-min acquisition time and reconstructed from list-mode raw data to obtain scan durations of 1 min, 2 min, etc., up to a maximum of 6 min. For each of the scan durations, the segmental tracer uptake value (percentage of maximum myocardial uptake) from the CZT camera was compared by intraclass correlation with standard SPECT camera data using a 20-segment model, and clinical agreement was assessed per coronary territory. Scan durations above which no further relevant improvement in uptake correlation was found were defined as minimal required scan times, for which Bland-Altman limits of agreement were calculated. Results: Minimal required scan times were 3 min for low dose (r 5 0.81; P , 0.001; Bland-Altman, 211.4% to 12.2%) and 2 min for high dose (r 5 0.80; P , 0.001; Bland-Altman, 27.6% to 12.9%), yielding a clinical agreement of 95% and 97%, respectively. Conclusion: We have established the minimal scan time for a CZT solid-state detector system, which allows 1-d stress/rest MPI with a substantially reduced acquisition time resulting in excellent agreement with regard to uptake and clinical findings, compared with MPI from a standard dualhead SPECT g-camera.Key Words: clinical cardiology; SPECT; cadmium-zinc-telluride detector; myocardial perfusion imaging; ultrafast Ischemi c coronary artery disease is a major cause of morbidity and mortality in industrialized countries. The hemodynamic relevance of culprit lesions can be detected and quantified noninvasively by nuclear myocardial perfusion imaging (MPI), which has grown to become the most frequently used test in nuclear medicine (1) not only for accurate diagnosis of ischemic coronary artery disease but also for assessing prognosis and for imaging myocardial viability and function (2). However, time-consuming acquisitions and cumbersome MPI protocols, with the associated costs, impaired patient comfort, and radiation exposure, have been perceived as limitations. Several attempts to improve the MPI method by using iterative reconstruction algorithms (3,4), early-imaging protocols (5), or different tracers (6) provided valuable results but no breakthroughs translating into applications that improve daily clinical routine. The novel cadmium-zinc-telluride (CZT) detectors may have the potential to represent such a milestone in technical improvement of MPI. They offer a substantially improved count sensitivity as evidenced in preliminary reports (7) and first clinical studies (8,9) performed on a device (D-SPECT; Spectrum Dynamics) with 9 rotating CZT detectors. An alternative approach ...

Myocardial perfusion imaging with SPECT (SPECT-MPI) and 64-slice CT angiography (CTA) are both established techniques for the noninvasive evaluation of coronary artery disease (CAD). Three-dimensional (3D) SPECT/CT image fusion may offer an incremental diagnostic value by integrating both sets of information. We report our first clinical experiences with fused 3D SPECT/CT in CAD patients. Methods: Thirty-eight consecutive patients with at least 1 perfusion defect on SPECT-MPI (1-d adenosine stress/rest SPECT with 99m Tc-tetrofosmin) and 64-slice CTA were included. 3D volume-rendered fused SPECT/ CT images were generated and compared with the findings from the side-by-side analysis with regard to coronary lesion interpretation by assigning the perfusion defects to their corresponding coronary lesion. Results: The fused SPECT/CT images added information on pathophysiologic lesion severity in 27 coronary stenoses (22%) of 12 patients (29%) (P , 0.001). Among 40 equivocal lesions on side-by-side analysis, the fused interpretation confirmed hemodynamic significance in 14 lesions and excluded functional relevance in 10 lesions. In 3 lesions, assignment of perfusion defect and coronary lesion appeared to be reliable on side-by-side analysis but proved to be inaccurate on fused interpretation. Added diagnostic information by SPECT/CT was more commonly found in patients with stenoses of small vessels (P 5 0.004) and involvement of diagonal branches (P 5 0.01). Conclusion: In addition to being intuitively convincing, 3D SPECT/CT fusion images in CAD may provide added diagnostic information on the functional relevance of coronary artery lesions. A precise, noninvasive technique for the diagnosis of coronary artery disease (CAD) should provide complementary information on coronary artery anatomy and pathophysiologic lesion severity (1-4). Although this can be achieved by mental integration of the information from coronary angiography (CA) and SPECT myocardial perfusion imaging (SPECT-MPI), standard myocardial distribution territories correspond in only 50%-60% with the real anatomic coronary tree (5). Several pioneering attempts of software-based image fusion from conventional CA and SPECT-MPI have been paving the way but were not implemented into clinical practice because its invasiveness precluded its use for noninvasive preinterventional decision making (5-8).Recently, 64-slice CT angiography (CTA) has emerged as a truthful alternative to conventional CA, with excellent diagnostic accuracy, in selected patients (9,10). Combined with the advancements in fast-processing software for 3-dimensional (3D) reconstructions (11), this has allowed initial promising attempts of purely noninvasive SPECT/ CT, directly relating individual myocardial wall territories to the subtending coronary artery (12-14).The increasing interest in cardiac fusion imaging is currently raising the question of its clinical feasibility and usefulness. An evaluation seems all the more pertinent, as the integration of SPECT or PET scanners and high-end CT...

DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.