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Biomedical subjects

E G DePuey

Publications and source records attributed to E G DePuey.

At least 19 recordsLinked to original sources
PubMed1997

Comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi SPECT imaging (perfusion and ECG-gated SPECT) in detecting coronary artery disease in women.

OBJECTIVES: This prospective study was conducted in 115 women to directly compare the sensitivity and specificity of thallium-201 (Tl-201), technetium-99m (Tc-99m) sestamibi perfusion and Tc-99m sestamibi electrocardiographic (ECG)-gated single-photon emission computed tomographic (SPECT) studies for detection of coronary artery disease (CAD). BACKGROUND: Data on the comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi perfusion imaging for the detection of CAD, specifically in women, are very limited. METHODS: Eighty-five patients with suspected CAD, scheduled for coronary angiography, and 30 volunteers with a pretest likelihood of < or = 5% for CAD were evaluated. Within 1 week, each patient underwent Tl-201 and Tc-99m sestamibi SPECT imaging procedures (both perfusion and gated SPECT imaging). Treadmill stress testing was used in 78 patients and dipyridamole in the remaining 37 patients. All images were interpreted by three observers in a blinded manner (consensus reading). Technetium-99m sestamibi SPECT studies were read without and then with ECG gating. Technetium-99m sestamibi gated SPECT studies were used to differentiate scar tissue from soft tissue attenuation artifact. RESULTS: The overall sensitivities for detecting > or = 50% and > or = 70% stenoses were 75.0% and 84.3%, respectively, for Tl-201, and 71.9% and 80.4%, respectively, for Tc-99m sestamibi perfusion studies (p = 0.48). The specificity for lesions > or = 50% was 61.9% for Tl-201 and 85.7% for Tc-99m sestamibi perfusion (p = 0.07), whereas for lesions > or = 70% it was 58.8% for Tl-201 and 82.4% for Tc-99m sestamibi perfusion (p = 0.01). When the 34 patients with a normal coronary angiogram were added to the group of 30 normal volunteers, the "specificity" for lesions > or = 70% was 67.2% for Tl-201, 84.4% for Tc-99m sestamibi SPECT perfusion (p = 0.02) and 92.2% for Tc-99m sestamibi gated SPECT (p = 0.0004). CONCLUSIONS: Both Tl-201 SPECT and Tc-99m sestamibi SPECT perfusion studies had a similar sensitivity for the detection of CAD in women. However, Tc-99m sestamibi SPECT perfusion imaging shows a significantly better specificity, which is further enhanced by the use of ECG gating.

Case-Control Studies↗
PubMed1995

Fast stress and rest acquisitions for technetium-99m-sestamibi separate-day SPECT.

UNLABELLED: Abbreviated acquisition protocols were designed for stress and rest to decrease stress and rest SPECT image acquisition times but maintain the high count density of 99mTc-sestamibi separate-day cardiac images. METHODS: Scan findings were compared visually and quantitatively with standard SPECT for 12 rest and 32 stress patient studies. RESULTS: Of 29 stress defects detected by standard SPECT, 27 were present with the fast technique; of 8 resting SPECT defects, all were detected with fast SPECT. Two stress and no resting false-positive defects occurred with fast SPECT. Linear correlations (r) between standard and fast quantitative defect extent and severity were 0.76 and 0.86, respectively for stress SPECT, and 0.88 and 0.96 for rest SPECT. Stress fast defects were slightly less severe (p = 0.02) than those observed using standard acquisition. CONCLUSION: We conclude that these fast protocols for separate-day 99mTc-MIBI SPECT accurately detect and characterize perfusion defects and provide a means to improve patient tolerance and increase laboratory throughput.

Coronary Disease↗
PubMed1995

Using gated technetium-99m-sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact.

UNLABELLED: Perfusion-scan fixed defects may result from soft tissue attenuation, decreasing test specificity for coronary disease and myocardial infarction (MI). Gated 99mTc-sestamibi SPECT may help differentiate MI from artifact since fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts either have normal function or at least do not demonstrate markedly reduced function. METHODS: Ungated resting and gated stress 99mTc-sestamibi SPECT was performed in 551 consecutive patients referred for evaluation of coronary disease. From resting and summed gated stress images, 180 patients (33%) were identified with isolated fixed defects. Function of the defects was assessed subjectively from gated stress images and results were correlated with clinical (history and/or ECG Q-waves) evidence of MI. RESULTS: Of 102 patients with fixed defects and clinical MI, 98 (96%) had abnormal defect function. Of 78 patients with no clinical MI, 18 (23%) had decreased function of the defect, possibly indicating silent MI. In 60 of the 78 patients (77%) with no clinical MI, defect function was normal. Because most (91%) of fixed defects with normal systolic function occurred in women with anterior fixed defects (48%) or men with inferior fixed defects (43%), these were most likely attenuation artifacts. By reclassifying patients with fixed defects and normal function as normal, patients with unexplained fixed defects (no clinical MI) decreased from 14% to 3%. CONCLUSION: Gating provides a valuable adjunct to 99mTc-sestamibi SPECT in characterizing fixed defects and potentially improving test specificity.

Artifacts↗
PubMed1994

Simultaneous biplane first-pass radionuclide angiocardiography using a scintillation camera with two perpendicular detectors.

UNLABELLED: Generally performed in a single anterior or right anterior oblique (RAO) view, first-pass radionuclide angiocardiography (RNA) is limited due to its inability to evaluate septal and posterior wall motion. METHODS: Thirty-five patients undergoing stress/rest sestamibi SPECT (22 mCi/22 mCi 2-day protocol) underwent biplane RNA at the time of resting injection. The stress SPECT images (acquired with the patient at rest) were ECG-gated to evaluate resting regional myocardial wall thickening. By this means wall motion assessed by RNA was compared to the presence of a resting SPECT perfusion defect accompanied by a localized decrease in wall thickening. RESULTS: In 16 patients in whom both resting perfusion and wall thickening were normal one demonstrated apical hypokinesis by RNA in the RAO view. In the other 29 patients, a total of 58 resting segmental perfusion defects with abnormal wall thickening were present (12 anterior, 13 inferior, 14 apical, 11 septal and 8 posterolateral). Wall motion abnormalities were detected in all these patients and in 57/58 segments (98%) by biplane RNA. Septal and posterolateral wall motion abnormalities were detected in only the LAO RNA study. In three patients, wall motion abnormalities were detected by LAO imaging only. Of the remaining 87 normally perfused segments in these 29 patients, RNA wall motion was normal in 85. Two posterolateral segments demonstrated apparent hypokinesis, probably due to left atrial overlap in the LAO projection. CONCLUSION: Simultaneous biplane RNA accurately detects wall motion abnormalities frequently missed by single-plane RAO imaging.

Dipyridamole↗
PubMed1994

Reproducibility of thallium-201 exercise SPECT studies.

UNLABELLED: A detailed analysis of intrapatient reproducibility of exercise SPECT thallium studies is presented. METHODS: Twenty patients in stable condition were re-examined with exercise-redistribution SPECT201 Tl within 3-9 days without intervening procedures. At peak stress, 3.5 mCi 201Tl were given intravenously 1 min prior to exercise termination. SPECT imaging started at 5 and 180 min. Acquisition and processing protocols were the same for all studies. Coronary angiography was performed on 19 patients and showed coronary artery disease (CAD) in 18, and no CAD in one; one patient did not have coronary arteriography. RESULTS: For 16 of 20 patients, exercise levels and ECG were comparable for both studies. Ten patients reproduced ST-segment depression; two reproduced angina; one had left bundle branch block (LBBB) on both studies after 1 min of exercise. The remaining seven patients had no ECG changes or symptoms during exercise. Four of 20 (20%) thallium scans differed: three in degree of redistribution and one (5%) in presence of a second stress defect. In three of four patients whose thallium studies showed some nonreproducibility, there were differences in exercise. Thallium results were identical in 15 of 16 patients whose ECG/exercise tests were reproducible (94%). Interobserver agreement was 95%. CONCLUSION: There was excellent reproducibility of 201Tl SPECT scintigraphy in patients who reproduced exercise test performance and symptoms.

Coronary Angiography↗
PubMed1994

First-pass ventricular ejection fraction using a single-crystal nuclear camera.

UNLABELLED: The purpose of the study was to evaluate the reliability of ejection fractions obtained from first-pass radionuclide ventriculography with a large field-of-view tomographic single-crystal gamma camera. METHODS: A SPECT camera had its electronics redesigned to improve counting efficiency and was equipped with an experimental ultra-high sensitivity collimator. Left ventricular ejection fraction (LVEF) was measured in 28 patients by 30 degrees RAO first-pass imaging and by "best septal view" LAO planar equilibrium radionuclide ventriculography on a conventional small field of view Anger camera. For 28 other patients, first-pass ejection fractions were compared to multicrystal gamma camera values. Visual analysis was performed to judge clinical acceptability of first-pass images for identification of wall-motion abnormalities. RESULTS: Linear regression analysis of first-pass against equilibrium ejection fraction demonstrated good correlation (r = 0.92; slope = 0.90; intercept = 3.8; s.e.e. = 6.4%). First-pass ejection fraction values also correlated linearly with multicrystal camera values for the left ventricle (r = 0.94; slope = 1.05; intercept = 1.3; s.e.e. = 5.3%). For a subgroup of 19 patients, single-crystal camera right ventricle ejection fraction demonstrated good correlation with multicrystal camera values (r = 0.82; slope = 1.15; intercept = 1.3; s.e.e. = 6.1%). Interobserver variability correlated as r = 0.99 for LVEF ejection fraction and r = 0.92 for RVEF. Chi-square analysis of single-crystal first-pass image visual scores versus those from the gated equilibrium acquisitions showed close agreement (p < 10(-8)). CONCLUSIONS: The evaluated camera/collimator system measured left and right ventricular ejection fraction accurately. Lung frame correction and dual regions were superior to paraventricular background correction and a fixed end-diastolic region.

Feasibility Studies↗
PubMed1994

How to detect and avoid myocardial perfusion SPECT artifacts.

Although myocardial perfusion imaging with SPECT is an accurate and reliable diagnostic study, artifacts must be avoided, or detected and corrected, to minimize the rate of false-positive results. Common sources of artifacts are nonuniformity in gamma camera detectors, center of rotation errors, misaligned cameras on multidetector scanner systems, errors in image reconstruction, patient motion, radiotracer uptake in nontarget organs and attenuation. Some of these artifacts can be avoided by quality control of instrumentation and by imaging the patient in a prone rather than supine position to separate radiotracer activity from the target and nontarget organs and to reduce the effect of inferior wall attenuation. Other artifacts can be detected by careful image inspection and corrected by reprocessing. The best way to avoid artifacts is to pay very close attention to the technical factors of image acquisition and processing, and to be aware of attenuation factors.

Artifacts↗
PubMed1993

Left ventricular ejection fraction assessed from gated technetium-99m-sestamibi SPECT.

By means of ECG gating of tomographic (SPECT) 99mTc-sestamibi (MIBI) images, myocardial perfusion and wall thickening have been evaluated after a single tracer injection. To determine if left ventricular ejection fraction (LVEF) can also be measured from gated MIBI SPECT, 30 patients 1 wk to 6 mo after myocardial infarction (MI) received 22-30 mCi 99mTc-MIBI during treadmill exercise. Eight frame per cardiac cycle gated MIBI 180 degrees SPECT was performed 60 min thereafter. Using 6.4-mm thick mid-ventricular vertical and horizontal long-axis slices from R-wave triggered end-diastolic and end-systolic frames, two independent observers manually drew endocardial borders at a count level of 34% of the maximum. LVEF was computed by the Simpson's rule method, corrected for the average point spread function of the SPECT camera. Results were correlated with LVEF determined from planar gated 99mTc-blood-pool studies performed within 4 days. LVEFs calculated from gated MIBI SPECT ranged from 0.21 to 0.73 and correlated linearly with gated blood-pool values (correlation coefficients ranged from 0.79 to 0.88; interobserver variability r = 0.75; intraobserver reproducibility r = 0.75). We conclude that in patients with MI resting LVEF can be determined from gated MIBI SPECT, thereby considerably augmenting the technique's diagnostic and prognostic value.

Adult↗
PubMed1991

Pharmacological and other nonexercise alternatives to exercise testing to evaluate myocardial perfusion and left ventricular function with radionuclides.

Pharmacological vasodilatation with either dipyridamole or adenosine is a safe and accurate alternative to exercise testing to diagnose coronary artery disease with thallium 201 myocardial perfusion imaging. The technique also provides important prognostic information with regard to future cardiac events in patients undergoing diagnostic testing, in those evaluated preoperatively, and in those with recent myocardial infarctions. Multigated equilibrium and first-pass radionuclide ventriculography also are well suited to evaluate the effects of interventional procedures. Success has been achieved using this methodology in a variety of interventions including conventional exercise testing, pharmacological stress testing, atrial pacing, assessment of myocardial viability with nitroglycerin, mental stress testing, and ambulatory monitoring of left ventricular ejection fraction.

Adenosine↗
PubMed1991

Radionuclide methods to evaluate percutaneous transluminal coronary angioplasty.

Radionuclide angiocardiography and myocardial perfusion imaging with exercise are valuable methods to assess patients undergoing percutaneous transluminal coronary angioplasty. Successful angioplasty results in improvement in ventricular systolic and diastolic function and regional perfusion. Complications of angioplasty, such as periprocedural infarction and side branch occlusion, can be documented noninvasively. Radionuclide methods have also been demonstrated to be of prognostic value in predicting coronary artery restenosis and recurrent cardiac symptoms. However, to avoid underestimating the success of coronary revascularization, studies must be scheduled long enough following angioplasty to allow transient abnormalities associated with artery dilation to resolve.

Angioplasty, Balloon, Coronary↗
PubMed1991

Evaluation of right ventricular regional perfusion with technetium-99m-sestamibi SPECT.

To evaluate technetium-99m-sestamibi as a right ventricular perfusion imaging agent, 25 normal volunteers and 25 patients with suspected coronary disease were studied with both sestamibi and thallium-201 SPECT. All patients underwent cardiac characterization. Compared to thallium-201 images, visualization of the right ventricle was superior for sestamibi in all cases. After computer masking of the left ventricle, count profiles for each 6-mm right ventricular short-axis slice were extracted and plotted in a bull's-eye type polar map with images normalized to maximal right ventricular counts. On sestamibi right ventricular polar maps, 7 of 11 patients (64%) with right coronary stenosis had fixed or reversible inferior right ventricular defects. None of the 25 volunteers or patients without right coronary stenosis had right ventricular defects (true-negative rate = 100%). We conclude that sestamibi SPECT provides an accurate means to assess right ventricular regional perfusion, with data presentation and interpretation facilitated by the polar map display.

Adult↗
PubMed1991

A review of cardiac imaging with sestamibi and teboroxime.

Overall, it is clear that the two new technetium-labeled compounds can provide diagnostic myocardial perfusion imaging both at stress (exercise and pharmacologic) and rest, but they have very different mechanisms of transport in comparison to each other and to thallium. Therefore, new imaging protocols will need to be developed and refined by practical experience as the use of these agents expands. Further investigative work needs to be done to optimize protocols and computer processing of images. In addition, special clinical situations will become associated with the use of these new compounds. Nuclear cardiology will continue to advance during this time of great changes and challenges if informational exchange on these topics continues to flourish and critical clinical trials are completed.

Coronary Disease↗
PubMed1991

Exercise supplementation of dipyridamole for myocardial perfusion imaging.

The substitution of intravenous dipyridamole for symptom-limited treadmill exercise has provided a non-invasive means to diagnose coronary artery disease with 201Tl scintigraphy in patients unable to adequately exercise. Limitations of dipyridamole/thallium imaging are primarily due to suboptimal image quality secondary to hepatic tracer concentration and decreased test sensitivity in patients who are dipyridamole "non-responders." Low-level treadmill exercise supplementation improves image quality, whereas handgrip has little, if any, benefit. The effect of low-level exercise in augmenting coronary blood flow is unknown and reports regarding the effect of handgrip are conflicting. The diagnostic benefit of these maneuvers in improving test sensitivity and decreasing the number of "non-responders" has not been documented. The combination of maximal, symptom-limited treadmill exercise and intravenous dipyridamole is a theoretically attractive option to improve overall test sensitivity, but the physiologic consequences and potential side effects should be more thoroughly investigated.

Coronary Disease↗