Comparison of indium-111 antimyosin antibody and technetium-99m pyrophosphate localization in reperfused and nonreperfused myocardial infarction.

Recent imaging studies suggest that technetium-99m (Tc-99m) pyrophosphate yields a considerably larger estimate of myocardial infarct size than does indium-111 (In-111) monoclonal antimyosin antibody. To determine whether Tc-99m pyrophosphate may be taken up by reversibly injured myocytes, particularly in the setting of coronary reperfusion, the tissue localization of Tc-99m pyrophosphate and antimyosin antibody was compared in 11 dogs 24 to 68 h after anterior descending coronary artery occlusion (4 dogs with permanent occlusion, 7 with reperfusion). Technetium-99m pyrophosphate and In-111 antimyosin antibody content was determined in serial 2 to 3 mm wide endocardial and epicardial samples taken through the infarct zone in multiple short-axis left ventricular slices. The number of samples with increased In-111 antimyosin antibody (defined as greater than or equal to mean + 2 SD of normal) was not significantly different from that with increased Tc-99m pyrophosphate. This was true in both reperfused and nonreperfused infarcts. However, the intensity of uptake of Tc-99m pyrophosphate exceeded that of In-111 antimyosin antibody, particularly in the border zones of reperfused infarcts, and the area with moderate to marked increase in tracer uptake (greater than or equal to 2 times normal) was significantly larger with Tc-99m pyrophosphate than In-111 antimyosin antibody (p less than 0.001). A specific zone of abnormal Tc-99m pyrophosphate with normal In-111 antimyosin antibody content could not be identified. Histologic evidence of myocardial necrosis was found in virtually every sample with increased In-111 antimyosin antibody, Tc-99m pyrophosphate, or both.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of Tl-201, Tc-99m sestamibi, and Tc-99m tetrofosmin myocardial perfusion scintigraphy in patients with mild to moderate coronary stenosis.

BACKGROUND: Thallium 201, technetium 99m sestamibi (MIBI), and Tc-99m tetrofosmin differ in their myocardial uptake characteristics. This may make the technetium tracers less sensitive for detecting mild to moderate coronary stenosis. METHODS AND RESULTS: We identified 163 patients with angiographic mild to moderate stenosis (50%-89%) and coexistent severe disease (88/163 patients) from a previous study of patients who received either thallium, MIBI, or tetrofosmin for myocardial perfusion scintigraphy. Summed segmental uptake scores were used to assess myocardial perfusion of territories supplied by the mildly to moderately stenotic vessels. Mean (+/- SD) summed stress uptake scores in the left anterior descending artery territory were 21.4 +/- 3.8, 21.6 +/- 4.2, and 22.1 +/- 2.3 for thallium, MIBI, and tetrofosmin, respectively (P = .7); mean summed difference uptake scores were 1.2 +/- 1.8, 1.1 +/- 1.9, and 1.0 +/- 1.1, respectively (P = .8). In the non-left anterior descending artery territory, mean summed stress uptake scores were 32.5 +/- 6.3, 34.0 +/- 6.3, and 34.5 +/- 4.7 for thallium, MIBI, and tetrofosmin, respectively (P = .4), whereas mean summed difference scores were 1.9 +/- 2.6, 1.7 +/- 2.2, and 1.7 +/- 2.3, respectively (P = .9). CONCLUSION: There were no significant differences between the tracers for the summed uptake scores. This suggests that the 3 tracers are comparable in clinical practice for assessing the extent and severity of perfusion abnormalities arising from mild to moderate coronary artery stenosis, especially in the presence of coexistent severe disease.     

A comparative study of myocardial infarct detection using Tc99m pyrophosphate and In111 DTPA antimyosin (R11D10 Fab)

Summary A crossover study to examine the potential of In¹¹¹ antimyosin Fab fragment to detect fresh myocardial infarcts in comparison with Tc^99m pyrophosphate is reported. In 27 cases indium antimyosin correctly diagnosed 19 patients with infarcts and 4 true negatives. There were also 2 false positive and 2 false negative scintigrams. Tc^99m pyrophosphate detected 21 infarcts and 6 true negatives correctly.     

Relationship between Tl-201, Tc-99m (Sn) pyrophosphate and F-18 2-deoxyglucose uptake in ischemically injured dog myocardium

We have previously demonstrated that enhanced glucose utilization in reperfused myocardium as assessed by F-18 2-deoxyglucose (FDG) and positron tomography predicts functional recovery. In this study, we compared segmental uptake of F-18 FDG with that of Tl-201 and Tc-99m (Sn) pyrophosphate (Tc-99m PPi) as conventional markers of tissue viability in seven dogs after a 3-hour intracoronary balloon occlusion and 20 hours of reperfusion. Myocardial blood flow was determined with microspheres. Regional retention fractions were calculated from tracer tissue concentrations, the arterial input function, and blood flow. Ischemic injury was assessed by triphenyltetrazolium chloride (TTC) staining and histologic analysis. At 24 hours, blood flow was 22% lower in reperfused than in control myocardium (p less than 0.05). Uptake of Tl-201 was related linearly to blood flow (r = 0.92), while glucose utilization and Tc-99m PPi were 2.9 (p less than 0.01) and 4.7 (p less than 0.05) times higher in reperfused than in control myocardium. Retention fractions of Tc-99m PPi increased with the degree of ischemic injury, while F-18 FDG uptake was highest in segments with mild cell injury. Thus, in ischemically injured myocardium, Tl-201 primarily reflects blood flow. F-18 FDG as a marker of glucose utilization identifies ischemically injured but viable tissue. The admixture of necrotic cells can be determined with Tc-99m PPi. Our results indicate that a dual tracer approach might best characterize the presence and extent of reversibly and of irreversibly injured tissue in a given myocardial region.     

Results of myocardial scintigraphy in patients with left bundle-branch block using Tl-201 and Tc-99m-MIBI]

Tl-201 myocardial scintigrams in patients with left bundle-branch block (LBBB) are frequently non-diagnostic with respect to presence or absence of coronary artery disease (CAD). The new myocardial perfusion tracer Tc-99m-MIBI requires a different protocol due to its insignificant redistribution. Therefore, scintigraphic patterns in LBBB cannot be deduced from experiences with Tl-201. In a total of 132 patients with LBBB, 81 studies were carried out with Tl-201, another 81 studies with Tc-99m-MIBI. In 30 patients both radiopharmaceuticals were employed. 72% of the Tl-201 scintigraphies in constant LBBB resulted in a reversible septal deficit and 9% in a constant septal deficit. In contrast, 70% of the Tc-99m-MIBI scintigraphies resulted in a constant septal deficit and only 19% in a reversible septal deficit. Similar "discrepancies" were found in LBBB patients in whom CAD has been angiographically excluded (N = 17). All patients, however, with LAD or RCA stenoses and constant LBBB showed reversible septal deficits with either tracer, Tl-201 (N = 12) or Tc-99m-MIBI (N = 10). It is concluded: 1) that the majority of patients with LBBB has reduced septal perfusion, 2) that this reduction is typically stress-independent in absence of CAD, and 3) that this stress-independent perfusion deficit is, in general, only differentiated from stress-induced ischemia (in case of CAD) with using the Tc-99m-MIBI protocol.     

Dual myocardial imaging with technetium-99m pyrophosphate and thallium-201 for detecting, localizing and sizing acute myocardial infarction.

In order to assess and compare the sensitivity and accuracy of technetium (Tc)-99m pyrophosphate and thallium-201 (Tl-201) in detecting, locating and sizing acute myocardial infarction with respect to the biochemically measured extent of infarction, myocardial imaging with both agents using a gamma scintillation camera was performed in 35 patients with documented acute myocardial infarction within 1 to 5 days after the onset of acute symptoms. Tc-99m pyrophosphate scintigrams were abnormal in 30 patients (86 percent) and the location of uptake corresponded to the electrocardiographic site of the infarct in 23 of the 30 patients (77 percent). The five negative Tc-99m pyrophosphate scintigrams included two from patients with a subendocardial infarction. By contrast, all 35 TI-201 myocardial images showed areas of decreased uptake and 33 (94 percent) corresponded to the electrocardiographic location of the infarct. In three patients with a prior myocardial infarction, separate defects were noted in addition to areas of decreased TI-201 uptake corresponding to new Q waves and ST-T wave changes. Additional abnormal areas in the scintigrams not suggested by the electrocardiogram were noted with Tc-99m pyrophosphate in 9 patients and with TI-201 in 16 patients; in 6 of these patients these areas were identical in extent and location in both radionuclide studies. In patients with negative Tc-99m pyrophosphate scintigrams, the average infarct size obtained from completed creatine kinase (CK) curves using serial serum CK values was smaller at 3.2 ± 0.5 (standard error) IU/literhour than in those with positive images (26.9 ± 4.1 IU/literhour; P <0.02). The planimetered area of Tc-99m pyrophosphate uptake that projected largest in one of the three views averaged 33.2 ± 4.6 cm² in patients with anterior or lateral infarction but only 18.9 ± 2.5 cm² (P <0.03) in patients with inferior infarction, whereas mean infarct size as assessed with CK values was not different in both groups. Correlation between infarct size as assessed with CK curve and area as assessed with Tc-99m pyrophosphate uptake was good (r = 0.90) in anterior infarctions but only fair (r = 0.64) in inferior infarctions.     

Thallium-201 versus technetium-99m pyrophosphate myocardial imaging in detection and evaluation of patients with acute myocardial infarction

Thallium-201 myocardial imaging is of value in the early detection and evaluation of patients with suspected acute infarction. The extent of a thallium defect in an initial myocardial image may have important prognostic value. Tomographic imaging techniques hold promise for increased diagnostic sensitivity and more accurate quantitation of both infarcted and residual viable myocardium. Thallium imaging may have a special value in characterizing patients with cardiogenic shock and in detecting patients at risk for subsequent infarction or death or both, before hospital discharge.

Approximately 95 percent of patients with transmural or nontransmural myocardial infarction can be detected with technetium-99m pyrophos-phate myocardial imaging if the imaging is performed 24 to 72 hours after the onset of symptoms. Pyrophosphate imaging has been useful in localizing the site and determining the extent of acute myocardial infarction. The “doughnut” pattern is associated with a relatively large incidence of subsequent congestive heart failure and death. However, the clinical utility of this information is limited because it is usually not available when it is most needed, on admission to the coronary care unit. Pyrophosphate imaging may have an important role in the evaluation of patients during the early follow-up period after hospital discharge from an episode of acute infarction. The finding of a persistently positive pyrophosphate image suggests a poor prognosis and is associated with a relatively large incidence of subsequent myocardial infarction and death.     

Preparation and evaluation of Tc-99m hydroxyethyl starch as a potential radiopharmaceutical for lymphoscintigraphy: comparison with Tc-99m human serum albumin, Tc-99m dextran, and Tc-99m sulfur microcolloid

Tc-99m hydroxyethyl starch (Tc-99m HES) prepared with a labeling efficiency greater than 95% was evaluated in rabbits for visualization of lymphatic channels and lymph nodes, and the findings compared with Tc-99m human serum albumin (Tc-99m HSA), Tc-99m dextran (Tc-99m DXT), and Tc-99m sulfur microcolloid (Tc-99m SMC). Tc-99m HES showed good visualization of lymphatic channels and regional nodes and it had the highest clearance rate from the injection site (p less than 0.01). Tc-99m HES showed greater uptake by the nodes than Tc-99m DXT (p less than 0.001) at 90 minutes post-injection. The concentration of Tc-99m HES in the lymphatic channels was higher than that of Tc-99m SMC at 90 minutes post-injection (p less than 0.001). Preliminary clinical studies of Tc-99m HES yielded high quality lymphoscintigrams of the leg, and the pelvic and para-aortic lymph nodes in less than 10 minutes post-injection. In addition, partially and completed obstructed lymphatics could be differentiated from normal lymphatic pathways. In conclusion, Tc-99m HES is a promising radiopharmaceutical for imaging of lymphatic channels and nodes.     

Noninvasive quantitation of myocardial infarction with technetium 99m pyrophosphate.

We sought to quantitate infarct size using radioactive imaging techniques. Infarcts were created in closed chest dogs. Using a scintillation camera interfaced to a computer, infarct images were made in the anterior, left lateral, LAO, and RAO projections, 48 hours after infarction and 75 to 90 min following the intravenous injection of 15 mCi of Technetium 99m pyrophosphate (Tc-PYP). Images were computer enhanced and area was calibrated with a radioactive grid source of known dimensions. Image radioactivity was normalized for decay and dose corrected for body weight. Animals were sacrificed two hours following the injection Tc-PYP. Postmortem images were also computer enhanced and calibrated. Gross infarct area and weight were estimated and transmural biopsies were evaluated for Tc-PYP activity and analyzed for creatine phosphokinase (CPK) content. Contiguous biopsies were pathologically analyzed and graded. There was a negative correlation between tissue Tc-PYP activity and CPK content (r=0.89). Pathologic severity worsened with increased Tc-PYP activity and diminished CPK content. There was a good correlation between gross infarct area and image infarct area, both in vivo (r     

Detection of traumatic myocardial injury by means of simultaneous T1-201/Tc-99m pyrophosphate tomography--report of three cases

Trauma to the chest can result in cardiac damage, which maybe missed by clinical examination because of associated injuries.Routinely performed non-invasive tests may also be non-diagnostic.Tc-99m pyrophos-phate (PPi) tomography, in this study combinedwith T1-201, is a promising addition to non-invasive evaluation.In three patients with cardiac injury, this technique successfullydetected and localized myocardial necrosis.     

Tc-99m tetrofosmin myocardial SPECT perfusion imaging: comparison of rest-stress and stress-rest protocols

Aim. The purpose of this study was to evaluate the diagnostic value of Tc-99m tetrofosmin SPECT myocardial perfusion scintigraphy rest/stress and stress/rest protocols for the assessment of coronary artery disease (CAD). Methods. 65 patients underwent both rest and stress SPECT imaging in a one-day protocol and coronary angiography within 2 months before or after scintigraphy. Scintigraphic data was obtained according to two different protocols; 1) rest-stress (n=18) and 2) stress-rest (n=47). Results. Scintigraphic evidence for myocardial ischaemia was found in 36 patients (55%). The overall sensitivity to detect CAD (>50% luminal stenosis) was 94% (34/36), specificity 66% (19/24), positive predictive value 77%, negative predictive value 90%. The sensitivity to detect CAD for protocols 1 and 2 were 100% and 93%, specificity 56% and 70%, positive predictive value 69% and 81% and negative predictive value 100% and 88%, respectively. The left anterior descending coronary artery showed a sensitivity (overall, protocol 1 & 2) of 78%, 75% (3/4) and 79% (15/19) and a specificity of 71%, 64% (9/14) and 75% (21/28). The right coronary artery showed a sensitivity (overall, protocol 1 & 2) of 91%, 100% (6/6) and 88% (14/16) and a specificity of 70%, 92% (11/12) and 61% (19/31). The left circumflex coronary artery showed a sensitivity (overall, protocol 1 & 2) of 50%, 67% (2/3) and 46% (6/13) and a specificity of 94%, 100% (15/15) and 91% (31/34). Conclusion. Tc-99m tetrofosmin appears to be a valuable tool in predicting significant CAD. The sensitivity and the positive predictive value are high, making this test highly appropriate for the diagnosis of CAD. The diagnostic value of the individual coronary arteries is high to moderate. No significant differences were found between both protocols.     

Prognostic value of stress-gated Tc-99m sestamibi SPECT after acute myocardial infarction

Stress-gated technetium-99m (Tc-99 m) sestamibi single-photon emission computed tomography (SPECT) is used to risk stratify patients after acute myocardial infarction (AMI). In clinical practice, results of this test are used primarily to identify patients with myocardial ischemia for intervention. The value of this test to risk stratify patients with AMI not at high ischemic risk has not been addressed. More than 1-year follow-up was undertaken in 124 patients who underwent predischarge gated Tc-99m sestamibi SPECT studies and who did not undergo subsequent revascularization. Clinical variables and test-derived variables were evaluated to predict cardiac death, recurrent AMI, and hospitalization for unstable angina, congestive heart failure, or coronary revascularization. Independent predictors by multivariate analysis for cardiac death or recurrent AMI were a history of prior AMI (relative risk [RR] = 5.32, confidence interval [CI] 2.17 to 12.96), a low exercise capacity (RR = 6.84, CI 1.99 to 23.48), and left ventricular (LV) ejection fraction (EF) <40% (RR = 2.63, CI 1.04 to 6.38). The incidence of cardiac death or recurrent AMI was 29.8% in patients with a low exercise capacity versus 4.5% in those with good exercise capacity, and 38.1% in patients with LVEF <40% versus 9.4% in those with LVEF >40%. Independent predictors of cardiac death, AMI, or hospitalization for unstable angina, congestive heart failure, or revascularization were a history of prior AMI (RR = 2.24, CI 1.11 to 4.50) and LVEF <40% (RR = 3.13, CI 1.64 to 5.95). Among patients followed after AMI without revascularization Tc-99m sestamibi SPECT can identify a high-risk subset. The strongest independent predictors are poor exercise capacity and LVEF < 40%.     

111In monoclonal antimyosin antibody imaging: imaging of myocardial infarction and myocarditis

A new scintigraphic method to detect myocardial necrosis has been developed using antimyosin monoclonal antibody Fab labeled with indium-111. Using this method, we studied 35 patients with myocardial infarction, 5 patients with myocarditis and 3 patients with angina pectoris. 111In antimyosin Fab was administered intravenously and antimyosin images were recorded by planar and single photon emission computed tomography (SPECT) 48 hours after injection. Planar images showed discrete localization of 111In antimyosin in 25 of 26 patients within 14 days after the onset of acute myocardial infarction. In 14 of these patients creatine kinase, glutamic oxaloacetic transaminase and lactic dehydrogenase had already normalized. Positive scans were also obtained in 6 of 12 patients between the third week to the ninth year after the onset of the disease. Three patients with acute myocarditis had positive scans 2 and 4 weeks after the onset of the disease. Thus, 111In antimyosin imaging may be a useful noninvasive method for the diagnosis of coronary diseases and myocarditis. Although the mechanism of persistent positive antimyosin images in the chronic stage remains to be clarified, 111In antimyosin scintigraphy holds potential promise as a non-invasive method for the detection of myocardial injury in the subacute to chronic stage as well as in the acute stage.     

Right ventricular myocardial infarction diagnosed by 99 m technetium pyrophosphate scintigraphy: clinical course and follow-up

Out of 178 consecutive patients with acute inferior wall myocardialinfarction submitted to technetium-99 m pyrophosphate scintigraphy,49 (27.5%) were found to have concomitant right ventricularinfarction. Gated blood pool scans showed right ventricularabnormalities in 21 out of 26 patients who were submitted tothis investigation (right ventricular asynergy: 16 cases; rightventricular dilatation: eight cases; decreased right ventricularejection fraction: 16 cases). Complications were common in the acute stage. Shock was notedin 19 cases (eight related to bradycardia, three related torelative hypovolaemia and eight instances of true cardiogenicshock). Atrial fibrillation (seven patients), ventricular fibrillation(eight patients) and severe atrioventricular conduction disorders(13 patients) were also frequent. In spite of this, the in-hospitalmortality was low: three deaths occurred (6.1%), one from heartfailure, two others from posterior septal rupture. All patients were followed up for one year or more. Six additionaldeaths were noted (three from left cardiac failure, two fromrecurrent anterior wall infarction and one from massive pulmonaryembolism). Clinical assessment, haemodynamic measurements andgated blood pool scans showed significant improvement of rightventricular function with return to normal in those cases withsmall right ventricular infarcts as judged from technetium-99m pyrophosphate scintigraphy. In spite of the complications seen in the initial period, patientswith a right ventricular infarction have a good overall prognosisand the long-term outcome, primarily determined by the left-sidedlesions, is often favourable.     

Scintigraphic visualization of myocardial infarcts in baboons using thallium-201 and technetium-99m pyrophosphate.

4 baboons with myocardial infarcts were evaluated using thallium-201 for myocardial imaging and 99Tcm pyrophosphate for infarct visualization. Scintiphotographic findings were compared with the size of myocardial infarcts calculated from measurements of the activity of MB isoenzymes of creatine kinase (CK-MB) in serum and in the myocardium at autopsy, as described by Sobel's method. Lack of thallium-201 accumulation was noted in left ventricular infarcts of 3 of the 4 baboons. These same areas localized 99Tcm pyrophosphate administered 24--30 h after infarction.