Dipyridamole has extensively been administered as a substitute for physical activity in cardiovascular assessment. The aim of this study was to evaluate the association of dipyridamole side effects with hemodynamic oscillations, scanning results, and electrocardiography (ECG) findings. Methods: Overall, 590 patients referred to the nuclear medicine center for myocardial perfusion imaging were evaluated for adverse dipyridamole effects concurrent with a low level of exercise. Before and during dipyridamole infusion, the patients' vital signs, electrocardiogram, heart rate, systolic blood pressure, and diastolic blood pressure were monitored; all patients underwent stress-rest 99m Tc-sestamibi gated SPECT using a 2-d protocol. Results: Eighty-eight patients (14.9%) experienced at least one side effect during dipyridamole infusion, and abnormal ECG and scan results were observed in 32.4% and 48.6% of patients, respectively. We observed a positive correlation between a higher incidence of chest discomfort, headache, and dyspnea and abnormalities on ECG and myocardial perfusion imaging. In addition, these 3 side effects were also associated with a higher postinfusion heart rate, lower preinfusion systolic blood pressure, and lower postinfusion diastolic blood pressure. There were significant differences between pre-and postinfusion heart rate, preinfusion systolic blood pressure, and postinfusion diastolic blood pressure among patients with or without side effects, whereas no significant difference was observed in any of the hemodynamic parameters between patients with normal and abnormal ECG results or myocardial perfusion imaging results. Conclusion: This study demonstrated a correlation between hemodynamic variables and side effects but not with imaging findings or ECG findings. The administration of dipyridamole during perfusion scintigraphy has extensively been applied to simulate the effects of physical activity in patients who are incapable of performing a conventional exercise test (1-3). The addition of a symptom-limited exercise test is also considered safe and efficient. Compared with dipyridamole infusion alone, exercise added to dipyridamole infusion has been shown to result in fewer noncardiac side effects, the same prevalence of angina pectoris, and a higher incidence of ST segment changes (4).Dipyridamole, by itself, can cause hypotension, dyspnea, dizziness, and electrocardiography (ECG) abnormalities; however, simultaneous dipyridamole administration and scanning should be treated as a distinct situation and demands its own risk assessment. Several studies have evaluated the safety and diagnostic precision of dipyridamole-thallium imaging in subjects with suspected coronary artery disease (5,6).The purpose of this study was to assess the incidence of dipyridamole side effects and their association with hemodynamic changes, scanning results, and ECG findings. MATERIALS AND METHODS Participants and Study DesignOverall, 590 patients (mean age 6 SD, 57 6 11 y) who underwent myocardial perfusion scanning...

In this paper we will present and explain coherently the two main algorithms which are currently used in commercial colour flow imaging systems, namely the frequency domain based autocorrelation algorithm and the time domain based cross correlation algorithm. The autocorrelation algorithm is a robust optimum mean frequency baseband estimator, for both high and low signal to noise ratio (SNR). Its main disadvantage is its aliasing problem. However the cross correlation algorithm does not suffer from this problem, and this has been one of the main reasons for its development. The mathematics behind these two algorithms and the general data processing steps used for their implementation will be also presented. The subject of clutter removal filtering will be discussed and valuable points will be made. A practical relevant approach on how to discriminate between wanted blood flow related estimates and unwanted false estimates due to noise will be presented. On the aliasing problem of the autocorrelation algorithm, a promising solution known as spatial tracking of estimated mean frequency does exist, which will be also introduced in detail. Towards the end of this paper other algorithms, which are currently the subject of research and have potential for development, will be discussed.

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Fetal Heart Rate(FHR) is one of the important features of fetal biophysical activity and its long term monitoring is used for the antepartum(period of pregnancy before labour) assessment of fetal well being. But as yet no successful method has been proposed to quantitatively represent variety of random, non-white patterns seen in FHR. Objective of this paper is to address this issue. In this study, the Box-Jenkins method of model identification and diagnostic checking was used on phonocardiographic derived FHR(averaged) time series. Models remained exclusively autoregressive(AR). Kalman filtering in conjunction with maximum likelihood estimation technique forms the parametric estimator. Diagnosrics perfonned on the residuals indicated that a second order model may be adequate in capturing type of variability observed in 1 up to 2 mm data windows of FHR. The scheme may be viewed as a means of data reduction of a highly redundant information source. This allows, a much more efficient transmission of FHR information from remote locations to places with facilities and expertise for doser analysis. The extracted parameters is aimed to reflect numerically the important FHR features. These are normally picked up visually by experts for their assessments. As a result long term FHR recorded during antepartum period, could then be screened quantitatively for detection of patterns considered normal or abnonnal.

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