Dual isotope thallium and indium antimyosin SPECT imaging to identify acute infarct patients at further ischemic risk.

Abstract

Forty-two patients (28 men and 14 women) with acute myocardial infarction (35 Q, seven non-Q wave) were injected with 2.0 mCi indium 111-labeled antimyosin (AM) monoclonal antibody (`111n AM) within 48 hours of the onset of chest pain. Forty-eight hours later (72-96 hours after onset of chest pain), patients were injected with 2.2 mCi thallium 201, and two sets of single-photon emission computed tomography (SPECT) images were obtained simultaneously using dual energy windows set for the 247 keV indium photopeak and the 70 keV thallium peak. Seventeen patients had repeat scans at 4 hours. "'in AM uptake and 201T1 defects were localized to one or more of 24 coronal and sagittal segments. Scans with only 201T1 defects and corresponding "'In AM uptake were classified as matches; scans with unmatched '0TI defects in addition to matching regions corresponding to electrocardiographic infarct location were classified as mismatches; and scans with 20MT1 and`'In AM uptake in the same segments were classified as overlap. Scan patterns were correlated with clinical evidence for residual ischemia occurring within 6 weeks of infarct and including infarct extension, recurrent angina, and positive predischarge low-level or 6-week symptom-limited stress tests and with coronary anatomy. Fourteen patients had only matching patterns (group 1), 23 had mismatches (group 2), and five had 201T1-1'In overlap as the predominant pattern. None of the patients in group 1 had previous myocardial infarction; in each, the matched area corresponded to the Q wave location on electrocardiogram, and none had further in-hospital ischemic events or positive stress tests. In contrast, nine patients in group 2 had previous myocardial infarction, and 16 of the 23 went on to have further evidence of ischemia. There was a significant correlation between further ischemic events and mismatching 201T1-111n AM activity (p<0.01). In conclusion, these results suggest that simultaneous SPECT imaging with 201T1 and`'In AM, performed 72-96 hours postinfarct, might be useful for identifying patients with benign in-hospital courses and those with myocardium at further ischemic risk. (Circulation 1990;81:37-45) E arly hospital discharge for some patients after acute myocardial infarction has been proposed.' It would be useful to identify patients who are likely to have benign postinfarction in-hospital courses early after the acute event. Likewise, identifying patients with further myocardium at ischemic risk early in their hospital course would help direct their physicians toward early catheterization and revascularization by either percutaneous transluminal coronary artery angioplasty (PTCA) or coronary bypass grafting. A decision-making point is atFrom the

Imaging of Acute Myocardial Infarction and Reperf usion

“…This is because the rabbit has no collater al circulation, extending the observation of Mody et al [24] to the case where flow is zero in the AR. Our observa tion is in agreement with and explains the data of Johnson et al [25]. In their study, there were many patients with AMI who had 20'TI perfusion defects but without anti- Fig.…”

Thallium and indium antimyosin dual-isotope single-photon emission tomography in acute myocardial infarction to identify patients at further ischaemic risk

“…Therefore a vasospasm or thrombotic artery occlusion with subsequent thrombolysis (either spontaneously or due to treatment) might have been the cause of MI in this patient. Lack of collateral vessels and/or persistent occlusion of the infarct-related artery may also cause false-negative studies [14,24,25]. In this study, however, there was no correlation between antimyosin uptake and vessel patency or collateral status.…”

“…All images were read by two independent observers, with an interobserver agreement of 94%. The following classification was used [25]: match: antimyosin uptake in segments with thallium defect; mismatch: no uptake of either of the nuclides in corresponding segments, i.e. presence of perfusion abnormalities in the absence of antimyosin uptake; overlap: thallium uptake in segments with uptake of ~In antimyosin.…”

“…Small inferior MI and high residual blood pool activity have been discussed as possible reasons for false-negative antimyosin studies [14,24,25]. five patients without antimyosin uptake showed high residual blood pool activity.…”

Simultaneous technetium-99m/thallium-201 SPECT imaging with model-based compensation for cross-contaminating effects

“…Dual-isotope SPECT studies have a wide range of uses, including the evaluation of myocardial viability and perfusion (Liu et al, 1986;Johnson et al, 1987;Johnson et al, 1990;Alexander and Oberhausen, 1995), brain function (Juni et al, 1992;Devous et al, 1992aDevous et al, , 1992b, lung function (Klumper and Zwijnenburg, 1986), hyperparathyroidism (Sandrock et al, 1990;Neumann, 1992) and others. The radionuclides used for these studies also include a number of combinations, such as Tc-99m / Tl-201, Tc-99m / In-111, Tl-201 / In-111, Tc-99m / I-123, Tc-99m / Kr-81m, F-18 / Tc-99m and others.…”