Introduction: Rubidium-82 (Rb82) PET myocardial perfusion imaging (MPI) is becoming more widely used due to superior diagnostic accuracy and availability without an onsite cyclotron.For optimal myocardial blood flow (MBF) quantification with low test-retest variability, the injected Rb82 activity should be accurate, precise and delivered consistently over a short time interval.We evaluated PET MBF data obtained in a clinical setting using constant-activity-rate infusions from a new Rb82 elution system to identify useful quality assurance parameters and establish their normal limits.Methods: 4,006 patients underwent rest-stress dynamic 3D PET imaging (8,012 scans) using 10 MBq/kg, 30s constant-activity-rate 'squarewave' infusions of Rb82 over a 2.5-year period (680 imaging days).To obtain regional MBF estimates, a 1-tissue-compartment model was fit to the dynamic image data from 0-6 min after injection.MBF image quality was determined from the model goodness-of-fit (R²) polar-maps and K1 SNR = mean/standard deviation (SD), and evaluated vs. patient weight.Reliability of the MBF estimates was assessed using two derived quality assurance metrics to identify outlier values: i) total rest + stress K1 coefficient-of-variation (COV = SD/mean), and ii) log(rest/ stress K1 COV).Results: Kinetic model R² values were excellent on average: 0.98 ± 0.2 at rest and 0.98 ± 0.3 at stress, indicating that there was high quality fitting of the model across the population sample.SNR values were excellent, with slightly higher image quality at rest vs. stress (61 ± 18 vs 47 ± 15, p < 0.001).There was no correlation of image quality with weight, indicating that uniform image quality was maintained regardless of patient size.Total rest + stress K1 COV < 10% was determined to be a useful limit to identify outliers with potential modeling or image quality issues; 14 patients (0.35%) were outside the median + 5 × IQR range using this criterion.For the log(rest/stress K1 COV), the population median ± 3 × IQR = [-1.65,1.15] was found to be robust for identifying outliers, with only 0.27%, or 11 patients falling outside this range.QA evaluation of the outliers revealed that the majority of the dynamic images contained patient motion, suggesting that the resultant MBF (K1) values may not reliable in these cases. Conclusion:A 1-compartment kinetic model applied to dynamic Rb82 PET data obtained with 30s constant-activity-rate 'square-wave' infusions results in uniformly high-quality estimates of K1 and MBF.With the weight-based 10 MBq/kg dosing, image quality is consistently high over a wide range of patient weights.Total rest + stress K1 COV < 10% and log(rest/stress K1 COV) in the range of [-1.65, 1.15] are useful quality assurance metrics to identify outliers requiring investigation of potential technical issues, including patient motion.

Correlation between Cold Pressure Testing (CPT)/ 99 Tc MIBI-SPECT defects and intracoronary acetylcholine (ACH) paradoxical constriction was published by our group.The usefulness of CPT non -invasive diagnosis of dysfunction (ED) was demonstrated by our observation in coincidence with other authors.There is little information on ED incidence on moderate risk asymptomatic (MRA) patients according to ATP III/Framingham index.Objective: This study is aimed at analyzing the incidence and localization of 99 Tc MIBI/ SPECT myocardial perfusion (MP) defects during CPT as indicator of ED on MRA patients.Methods: 124 patients (78 female) currently compounding PARADIGMA Study Register were analyzed.PARADIGMA is a prospective multicenter study that will include once completed a total number of 450 MRA patients according to ATP III/ Framingham index (Ͻ 20% events at 10 years ), with normal exercise MP and no cardiovascular disease history.CPT-MP imaging was obtained in all these patients.MP extension score was used in a 17 segment model , reported by two observers on consensus.Mann-Whitney U Test statistical analysis was performed.l Results: positive CPT 25/113 patients (22,12 %).CPT extension perfusion score positive 5,77Ϯ2,38(pϽ0.0001).CPT was positive in 30,76 % men and 17,56 % women (pϽ0.001).Localization : anterior wall 4 3%,i n ferior wall 47 %, lateral wall 4,5% and anterior with inferior walls 4,5 %.Conclusion: These results suggest high incidence of ED on MRA patients, who are also free from exercise --related ischemia.There were no significant differences in clinical data and defects localization.Further studies will indicate whether this positive CPT population would have higher risk of cardiovascular events during follow-up Age, Bood Pressure and Cholesterol pns (*) AGE SBP DBP CHOLEST.HDL LDL TRIGL.CPT ( ϩ ) 55.

BACKGROUND:The mechanisms by which exercise training benefits patients with coronary artery disease (CAD) are unclear but may include improved myocardial circulation. The aim of this study was to investigate the effect of exercise training on myocardial blood flow (MBF) and coronary flow reserve (CFR) in patients with stable CAD.METHODS:Twelve patients with documented CAD and ischemic ST-segment depression during exercise testing were randomized to exercise training (n = 7) or sedentary life style (control; n = 5) and underwent rubidium-82 positron emission tomography pre- and postintervention. Global left ventricle MBF and regional MBF in 17 left ventricular segments were calculated. Segments with <75% uptake (2 SD below normal) on stress uptake images were defined as abnormal.RESULTS:Exercise training increased global CFR by 20.8% +/- 27.9% versus control (10.5 +/- 24.1%, P = .0001). In normal segments (exercise training: n = 91; control: n = 46), exercise training did not change resting MBF (-14.1% +/- 16.3% vs -8.8% +/- 15.6%) and hyperemic MBF (-1.93% +/- 19.1% vs 2.86% +/- 20.5%, P = NS) and increased in CFR compared to control (17.0% +/- 25.5% vs 11.3% +/- 23.5%, P = .01). In abnormal segments, the change in resting MBF was not significantly different (-12.6% +/- 18.5% exercise [28 segments] vs -2.9% +/- 18.0% control [39 segments], P = NS). A significant increase was seen in hyperemic MBF with exercise (12.5% +/- 22.1% vs 2.6% +/- 16.3%, P = .02) and CFR (32.8% +/- 32.3% vs 9.5% +/- 24.8%, P = .001).CONCLUSIONS:Exercise training increased CFR in normal and diseased segments, and increased hyperemic flow in diseased segments. These data provide preliminary evidence in support of a favorable effect of exercise training on blood flow to ischemic myocardium.

A formation-flying sensor that can determine spacecraft separation with a max- imum uncertainty of 2 cm, measure the bearing angles of the remote spacecraft with a maximum uncertainty of a minute of arc, and operate with a wide field of view autonomously in deep space has been designed and prototyped. It is the au- tonomous formation-flying (AFF) sensor that operates at 32 GHz (Ka-band) using technology similar to that of the Global Positioning System (GPS). A significant challenge lies in the simultaneous requirements for precision and a wide field of view, mandating a substantial technology development effort and design of a sensor with some novel features. Through development of a prototype, the AFF sensor has been extensively characterized and the key technology risks have been retired. It has been concluded that the AFF sensor can meet the (2-cm, 1-arcmin) require- ment within the StarLight two-spacecraft stellar optical interferometer mission. An overview of the sensor design, results of the technology development, conclusions of the technology investigations, and highlights of the related inter-spacecraft issues are presented in this article.

The StarLight Mission, an element of NASA's Origins Program, was designed for first-time demonstration of two technologies: formation flying optical interferometry between spacecraft and autonomous precise formation flying of an array of spacecraft to support optical interferometry. The design overview and results of the technology effort are presented in this paper.

Revascularization of occluded coronary arteries after myocardial infarction (MI) may restore flow to viable myocardium and improve ventricular function. The aim of this pilot study was to determine the potential utility of thallium-201 viability imaging for the prediction of recovery of regional ventricular function in patients undergoing revascularization of total or subtotal occlusion of infarct-related arteries (TIMI 0–2 flow) during the convalescent period after MI.