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 ...

The novel CZT camera allows a more than fivefold reduction in scan time and provides clinical information equivalent to conventional standard SPECT MPI.

MSCTA provides additional information to CS regarding stenosis severity and plaque composition. This additional information was shown to translate into incremental prognostic value over CS.

The ability to obtain quantitative values of flow and myocardial flow reserve (MFR) has been perceived as an important advantage of PET over conventional nuclear myocardial perfusion imaging (MPI). We evaluated the added diagnostic value of MFR over MPI alone as assessed with 13 N-ammonia and PET/CT to predict angiographic coronary artery disease (CAD). Methods: Seventy-three patients underwent 1-d adenosine stress-rest 13 N-ammonia PET/CT MPI, and MFR was calculated. The added value of MFR as an adjunct to MPI for predicting CAD (luminal narrowing $ 50%) was evaluated using invasive coronary angiography as a standard of reference. Results: Per patient, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MPI for detecting significant CAD were 79%, 80%, 91%, 59%, and 79%, respectively. Adding a cutoff of less than 2.0 for global MFR to MPI findings improved the values to 96% (P , 0.005), 80%, 93%, 89% (P , 0.005), and 92% (P , 0.005), respectively. Conclusion: The quantification of MFR in 13 N-ammonia PET/CT MPI provides a substantial added diagnostic value for detection of CAD. Particularly in patients with normal MPI results, quantification of MFR helps to unmask clinically significant CAD.Key Words: myocardial flow reserve; 13 N-ammonia; positron emission tomography; diagnostic value; myocardial perfusion imaging Nucl Med 2012; 53:1230 53: -1234 53: DOI: 10.2967 The PET technique confers advantages over SPECT related to improved image resolution and intrinsic attenuation correction (1). In addition, in myocardial perfusion imaging (MPI) PET offers quantitative assessment of myocardial blood flow (MBF) at rest and pharmacologic stress allowing calculation of myocardial flow reserve (MFR) (2). The latter is an index to evaluate blood circulation from the epicardial coronary arteries down to the microcirculation (3), which therefore provides functional information far beyond the epicardial section of the coronary vascular tree. Relative MPI such as SPECT (or PET without quantitative measurement) relies on induction of flow heterogeneities by hyperemic stress, which may sometimes underestimate the extent of coronary artery disease (CAD), as only the most severely underperfused territory may be evidenced (4). By contrast, absolute flow and MFR may reveal the true extent of CAD even at an early stage of subclinical atherosclerotic CAD. This possibility is supported by recent results documenting an added prognostic value for MFR over PET MPI alone with either 13 N-ammonia (5) or 82 Rb (6,7). Interestingly, MFR remained predictive throughout a 10-y follow-up period (5). Although many studies have revealed a reversed correlation of increasing coronary artery lesion narrowing with decreasing hyperemic flow and MFR in the respective myocardial territory (8-10), its diagnostic added value over MPI PET has not been assessed systematically. JWe evaluated the hypothesis that patients with decreased MFR (,2.0) would have a higher probability of CAD and that, thus, MFR would co...

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