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Biomedical subjects

P Rigo

Publications and source records attributed to P Rigo.

At least 127 records · Page 7Linked to original sources
PubMed1975

Ventricular arrhythmias in the late hospital phase of acute myocardial infarction. Relation to left ventricular function detected by gated cardiac blood pool scanning.

Abnormalities of left ventricular function and extent of myocardial infarction were studied in relation to prevalence of late ventricular premature contractions (VPCs) in 36 patients in the convalescent stage of acute myocardial infarction (MI). Left ventricular ejection fraction (EF) and percent akinesis (%A) were calculated from gated cardiac blood pool scans; myocardial infarct size was estimated from peak CPK values; and VPCs were detected by 24 hour ambulatory ECGs 2-4 weeks following hospitalization for acute MI. Twenty-two patients had either zero (class 0) or less than 30/hour unifocal VPCs (class I). Fourteen patients had greater than 30/hour unifocal (class II), multifocal (class III) or coupled VPCs (class IV), including ventricular tachycardia. Thirteen of 14 class II-IV patients had EF less than 40% compared with only 8 of 22 class 0-I patients. Class II-IV patients had significantly lower mean EF (30.5 +/- 2.3 SE to 49.6 +/- 4.0) P less than 0.01, higher mean %A (28.1 +/- 2.2 to 16.9 +/- 3.7) P less than 0.05, and higher mean peak CPK (1350 +/- 187 to 721 +/- 155) P less than 0.05 than class 0-I patients. These data suggest that VPCs may not be an independent risk factor for sudden cardiac death in the convalescent phase of MI.

Acute Disease↗
PubMed1975

Pre- and postoperative myocardial and blood pool scans in a case of left ventricular aneurysm: Case report.

Myocardial perfusion scans (using 131Cs) and blood pool scans (113mIn) were performed on a patient before and after resection of a left venticular aneurysm. Although the huge aneurysm was revealed by preoperative scans, preservation of a significant mass of myocardium was evident. Postoperative scans show the reconstructed heart and the amount of residual damage. The operative findings confirmed the reliability of the scan information.

Cesium Radioisotopes↗
PubMedDate not supplied

Reduced variability of interpretation and improved image quality with a technetium 99m myocardial perfusion agent: comparison of thallium 201 and technetium 99m-labeled tetrofosmin.

BACKGROUND: The purpose of this study was to determine the relative image quality and interobserver variability among four readers for 201Tl and 99mTc-labeled tetrofosmin myocardial perfusion images. 99mTc-labeled perfusion agents, with near-optimal physical characteristics for gamma camera imaging, may allow for superior image quality and improved consistency of interpretation. However, most studies to date have demonstrated only similarity in the diagnostic accuracy between technetium agents and thallium. Tetrofosmin is a recently developed 99mTc-labeled agent that has shown promising results in early clinical trials. METHODS AND RESULTS: A multicenter, open-label trial was performed during which treadmill exercise thallium and tetrofosmin scintigraphy was performed within a 2-week period of each other in 216 subjects. Image quality was evaluated subjectively and scans were interpreted in a blinded, independent fashion by four readers. Perfusion abnormalities were graded as consistent with ischemia, infarction, or mixed and were described both globally and regionally. Interobserver variability was assessed by use of the kappa statistic, and receiver-operator curves were compared for each observer for the diagnostic accuracy of each agent. More tetrofosmin images were of excellent quality than with thallium (52% vs 28%; p < 0.05), and when differences in quality were noted between the agents, tetrofosmin was more often superior (p < 0.0001). The interobserver variability was lower with tetrofosmin scintigraphy because generally higher kappa values were noted, especially in the lateral wall. Higher receiver-operator curve areas indicative of improved diagnostic accuracy were noted among the four readers for tetrofosmin in 80% of vascular territories. CONCLUSIONS: 99mTc-labeled tetrofosmin scintigraphy yields images of improved quality compared with thallium, and there is an overall improvement in the consistency of image analysis associated with the use of tetrofosmin.

Coronary Disease↗
PubMedDate not supplied

Myocardial single-photon emission computed tomographic imaging with technetium 99m tetrofosmin: stress-rest imaging with same-day and separate-day rest imaging.

BACKGROUND: Technetium 99m tetrofosmin is a new ethylene diphosphine ligand for myocardial perfusion imaging and has unique properties. We have compared stress-rest single-photon emission computed tomographic (SPECT) imaging with 99mTc tetrofosmin with same-day and separate-day rest imaging to detect myocardial perfusion defects. METHODS AND RESULTS: Myocardial SPECT imaging was performed in 22 patients with coronary artery disease who had undergone planar thallium 201 imaging and coronary angiography. Single-day (stress-rest) and separate-day rest 99mTc tetrofosmin SPECT protocols were compared in the same patient. Images were assessed by a blinded panel to identify myocardial infarction, ischemia, or normal scans. Overall sensitivity for identification of patients with coronary artery disease was 86% (19/22) by both same-day stress-rest and separate-day rest protocols with 99mTc tetrofosmin (p = NS). Of a total of 396 segments studied, 107 abnormal segments were identified at exercise and 76 and 81 at the same-day and separate-day rest tests, respectively (p = NS). Same-day stress-rest and separate-day rest 99mTc tetrofosmin SPECT protocols were also useful for detecting individual coronary stenosis with a greater than 50% lesion: 80% of the left anterior descending, 93% of the right coronary, and 75% of the left circumflex coronary arteries were detected. CONCLUSION: Excellent images were obtained with 99mTc tetrofosmin during both stress and rest. 99mTc tetrofosmin imaging with the same-day stress-rest and separate-day rest imaging protocols have similar diagnostic sensitivities for detection of coronary heart disease.

Aged↗
PubMedDate not supplied

Improved diagnostic accuracy of planar imaging with technetium 99m-labeled tetrofosmin compared with thallium-201 for the detection of coronary artery disease.

BACKGROUND: Receiver operating characteristic (ROC) curve analysis provides detailed information about the performance of a diagnostic test. METHODS AND RESULTS: As part of a multicenter phase III trial, 160 patients with known or suspected coronary artery disease underwent planar stress-rest 99mTc-labeled tetrofosmin and stress-redistribution 201Tl imaging within 14 days of each other, to compare the diagnostic accuracy of these imaging modalities by ROC curve analysis. Coronary arteriography was used as the reference standard and greater than 70% stenosis was considered significant. ROC curve analysis showed improved detection of coronary artery disease with 99mTc-labeled tetrofosmin compared with 201Tl, with ROC curve areas of 0.765 versus 0.644, respectively (p = 0.02). 99mTc-labeled tetrofosmin also better identified single-vessel disease in those without previous myocardial infarction (ROC curve areas of 0.684 vs 0.510 for 99mTc-labeled tetrofosmin and 201Tl, respectively; p = 0.04) and enhanced the detection of multivessel disease in those with previous myocardial infarction (ROC curve areas of 0.764 vs 0.638, respectively; p = 0.02). CONCLUSIONS: Detailed assessment of diagnostic performance by ROC curve analysis shows that, for planar imaging, 99mTc-labeled tetrofosmin enhances the detection of coronary artery disease compared with 201Tl.

Adult↗
PubMedDate not supplied

Quantitative evaluation of a comprehensive motion, resolution, and attenuation correction program: initial experience.

BACKGROUND: Tomographic myocardial imaging is widely used in the diagnosis and evaluation of patients with coronary artery disease. However, its specificity remains suboptimal because of attenuation, resolution, and motion artifacts. The purpose of this study was to optimize and assess the value of attenuation, blur, and motion correction of myocardial single photon emission computed tomographic data. METHODS AND RESULTS: Forty-seven studies were selected for analysis to provide 3 patient groups. Group A consisted of 18 patients with a low likelihood of coronary artery disease who were used to construct a quantitative normal database and assess changes in the normal bull's-eye produced by filtering and by attenuation correction. Group B consisted of 13 patients with a high probability of normal results, and group C consisted of 16 patients with coronary artery disease defined on angiography. The effects of attenuation correction, especially in conjunction with RESTORE (a depth-dependent deblurring filter), have been quantitated. Analysis indicates a trend to improved sensitivity and specificity for detecting individual vessel disease in this retrospective study. The motion correction program was successfully applied to 93% of patients but detected significant motion requiring correction in only 11 (24%) patients. CONCLUSION: This preliminary retrospective study indicates a potential for improved myocardial single photon emission computed tomography imaging with the use of attenuation and motion correction together with a restorative deblurring filter. Confirmation by a multicenter study and larger patient numbers remain necessary to assess fully the prospective value of the technique.

Adult↗
PubMedDate not supplied

Combined corrections for attenuation, depth-dependent blur, and motion in cardiac SPECT: a multicenter trial.

BACKGROUND: The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited by image-degrading factors, such as heart or subject motion, depth-dependent blurring caused by the collimator, and photon scatter and attenuation. We developed correction approaches for motion, depth-dependent blur, and attenuation and performed a multicenter validation. METHODS AND RESULTS: Motion was corrected both transversely and axially with a cross-correlation technique. Depth-dependent blurring was corrected by first back-projecting each projection and then applying a depth-dependent Wiener filter row by row. Attenuation was corrected with an iterative, nonuniform Chang algorithm, based on a transmission scan-generated attenuation map. We validated these approaches in 112 subjects, including 36 women (20 healthy volunteers, 8 angiographically normal patients, and 8 patients with coronary artery disease [CAD] found by means of angiography) and 76 men (23 healthy volunteers, 10 angiographically normal patients, and 43 patients with CAD found by means of angiography). Either technetium 99m or thallium 201 was used for emission; either gadolinium 153 or Tc-99m was used for transmission. Images were reconstructed and blindly interpreted with a 5-point scale for receiver operating characteristic analysis in 2 ways: motion correction plus a Butterworth filter, and combined motion and blur and attenuation corrections. The interpretation by means of consensus was for the overall presence of CAD and vascular territory. The receiver operating characteristic curves for overall presence and each of the 3 main coronary arteries were all shifted upward and to the left and had larger areas under the curve, for combined corrections compared with motion correction and Butterworth. Sensitivity/specificity for motion correction and Butterworth were 84/69, 64/71, 32/94, and 71/81 overall for the left anterior descending, the right coronary artery, and circumflex territories, respectively, compared with 88/92, 77/93, 50/97, and 74/95, respectively, for the combined corrections. CONCLUSIONS: The proposed combined corrections for motion, depth-dependent blur, and attenuation significantly improve diagnostic accuracy, when compared with motion correction alone.

Coronary Disease↗
PubMedDate not supplied

Considerations of 201T1 as a myocardial radionuclide imaging agent in man.

Recent reports have suggested the use of intravenous 201T1 (thallium-201) for myocardial imaging with the gamma scintillation camera. In order to better appreciate the possible utility of this agent in humans we examined its distribution and kinetics in 13 patients and in six mongrel dogs, three with experimental coronary artery occlusion. In addition, 201T1 was compared to 86Rb (rubidium-86) in 84 rats. In the rat heart, the concentration of 201T1 was 30% higher than that of 86Rb ten minutes after injection. Moreover, myocardium-to-blood ratios for 201T1 averaged 51:1, but only 32:1 for 86Rb ten minutes after administration. In the dog heart, the distribution of 201T1 paralleled that of radioiodinated (131I) albumin particles injected into the left atrium and, thus, appears to be related to regional blood flow. Its concentration in ischemic regions decreased to 32.3% of the normally perfused myocardium. In the patients with a recent or old myocardial infarction, areas of decreased 201T1 uptake were easily identified and corresponded in location to that by ECG. Repeat scans 24 hours after the initial injection showed a significant retention of 201T1 by the myocardium. 201T1 blood levels in humans 15 minutes after injection were low (averaging 1.06% +/- 0.41% SD of the total dose per liter) and these levels decreased with a biological half-life of 3.1 +/- 0.7 days. Twenty-four hour urinary excretion rates ranged from 0.6 to 6.5% of the total dose and appeared related to urinary flow and the concentation of 201T1 in blood. Because of the higher target to background ratios, 201T1 compares favorably with radioactive rubidium. 201T1 in diagnostic doses remained without detectable adverse effects and appears promising as an agent for visualizing abnormal regional myocardial perfusion in patients with coronary artery disease.

Adult↗
PubMedDate not supplied

Validation of a simple isotopic technique for the measurement of global and separated renal function.

Schlegel and Gates described an isotopic method for the measurement of global and separated glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) based on the determination by scintillation camera of the fraction of the injected dose (99mTc-DTPA-[131I]hippuran) present in the kidneys 1-3 min after its administration. This method requires counting of the injected dose and attenuation correction, but no blood or urine sampling. We validated this technique by the simultaneous infusion of inulin and polycyclic aromatic hydrocarbon (PAH) in patients with various levels of renal function (anuric to normal). To better define individual renal function we studied 9 kidneys in patients either nephrectomized or with a nephrostomy enabling separated function measurement. A good correlation between inulin, PAH clearance, and isotopic GFR-ERPF measurement for both global and separate renal function was observed.

Glomerular Filtration Rate↗
PubMedDate not supplied

Scintillation probe detector in the assessment of cardiovascular disease.

A simple device that permits measurement of cardiac function in humans after intravenous injection of technetium-99m-labeled albumin or red blood cells is described. The device (nuclear stethoscope cardiac probe) is based on the application of microprocessor technology to a scintillation detector. It can be used to monitor ventricular function continuously and in exercise testing for the detection of coronary heart disease.

Coronary Disease↗