Use of 99mTc-pyrophosphate and coronarography in the diagnosis of simultaneous myocardial infarct of the right and left cardiac ventricles]

Myocardial scintigraphy was performed using 99m-Tc-pyrophosphate in 50 patients with suspected coexisting right ventricular and left inferior ventricular heart infarction and in 50 patients with left inferior ventricular infraction only. In all survived patients additional selective coronarography was performed and in all died patients autopsy was performed. The aim of the study was to evaluate reliability of myocardial scintigraphy using 99m-Tc-pyrophosphate in the diagnosis of coexisting infarction of both heart ventricles. In a group of patients with coexisting right and left ventricular infarction (45 proved by coronarography, and 5 by autopsy), scintigraphic finding was confirmed in 46 (93%) patients. In all 50 patients with left inferior ventricular infarction, scintigraphic finding was confirmed in 48 of them by coronarography and in 2 by autopsy (100%). Of 4 patients with false negative scintigraphic finding 2 were treated with fibrinolytic therapy immediately after admission and in 2 diffuse occlusive changes were found on all three blood vessels by coronarography. It has been concluded that myocardial scintigraphy using 99m-Tc-pyrophosphate is a very sensitive (92%), specific (100%), exact (96%), simple and safe diagnostical method in detecting coexisting acute infarction of both heart ventricles.     

Assessment of myocardial necrosis by 111In-antimyosin F ab scintigraphy

111In-antimyosin F ab (AM) myocardial scintigraphy was carried out in (A) 13 patients with acute myocardial infarction (9.9 +/- 2.2 days from the onset) and (B) 9 with myocarditis and/or dilated cardiomyopathy. Forty eight hours after injection of AM, the patients were injected with 74 MBq (2 mCi) of thallium-201 (TL). The two sets of Planar and SPECT image were obtained simultaneously using dual energy window sets. In group A, positive focal AM uptake was demonstrated in 12 (92%) patients. Higher AM uptake was observed in patients who had PTCR/PTCA. By combination with TL, it is useful to detect inferior infarction and to differentiate old from acute infarction. Dual SPECT images gave precise information about the infarcted area. In group B, positive diffuse AM uptake was demonstrated in 7 (77%) patients. In conclusion, AM myocardial scintigraphy was proven to be useful for the assessment of acute necrosis after myocardial infarction but also on-going necrosis of myocarditis and/or myopathy.     

Clinical trial of 111In-antimyosin antibody imaging: (2). Imaging of myocardial infarction and myocarditis

A new scintigraphic method to detect myocardial necrosis has been developed using antimyosin monoclonal antibody F ab labeled with indium-111 (111In-antimyosin). We investigated 111In-antimyosin scintigraphy in 35 patients with myocardial infarction, 5 patients with myocarditis and 3 patients with angina pectoris. 111In-antimyosin F ab was administered iv and antimyosin images were recorded by planar and single photon emission computed tomography (SPECT) 48-72 hrs after injection. Planar images showed discrete localization of 111In-antimyosin in 26 of 27 patients within 16 days after the onset of acute myocardial infarction in 14 of whom creatine kinase, glutamic oxaloacetic transaminase and lactic dehydrogenase had already normalized. In addition, positive scans were also obtained in 4 of 8 patients 1 to 9 months after the onset of the disease. Three patients with acute myocarditis (two of whom were biopsy-proven) had positive scans 2 and 4 weeks after the onset of the disease. Although mechanism of persistent positive anti-myosin images in the chronic stage remains to be clarified, 111In-antimyosin scintigraphy holds potential promise as a noninvasive method for the detection of myocardial injury.     

99Tcm-Sn pyrophosphate scanning in suspected acute myocardial infarction using a mobile rectilinear scanner

99Tcm stannous pyrophosphate injected intravenously gives a positive image of freshly damaged myocardium but not of normal or scarred myocardium. It is safe, cheap and generally available. One hundred and forty patients admitted to hospital with possible myocardial infarction were scanned with a mobile rectilinear scanner of the type available in most district general hospitals. When the diagnosis of infarction was definite on clinical, electrocardiographic and enzyme criteria the anterior scan was positive in 31 out of 36 patients (86%); and when it was probable, the scan was positive in 28 out of 41 (68%) and when it was doubtful the scan was positive in 23 out of 63 (37%). The optimum time for scanning was between the second and seventh days. Pyrophosphate scanning is a very valuable investigation even though it is not an absolute discriminator of myocardial infarction. It is useful in assessing patients with atypical or doubtful symptoms of infarction where the ECG is already abnormal or where there are other causes of raised enzyme concentrations. False negative scans are not common, but a negative scan does not outweigh strong alternative evidence of infarction. Positive scans occur in some patients with unstable angina without confirmatory evidence of infarction. Positive scans due to extracardiac lesions are distinguished readily.     

MRI of acute myocardial infarction with injection of Gd-DOTA (15 patients)

We studied 15 patients 4 to 8 days after myocardial infarction by using ECG gated MR before and after administration of 0.2 mmol/kg Gd-DOTA. The diagnosis in each patient was confirmed by electrocardiographic criteria, elevated levels of fractionated creatine kinase (CK) isoenzyme, thallium scintigraphy, ventriculography and coronarography. T1-weighted, spin-echo images, were obtained before and immediately after injection of Gd-DOTA and were repeated 15 min later. The site of infarction was visualised in 10 patients as an area of high signal intensity after the injection of Gd-DOTA. Contrast between normal and infarcted myocardium was greatest 15 min after injection. Three patients were excluded because of failure to acquire adequate MR studies. In 2 other patients, the infarct were not detected. Before injection of Gd-DOTA, only 2 infarcts were detected. These results suggest that Gd-DOTA can improve MR visualisation and detection of acute myocardial infarction.     

The scintigraphic evaluation of myocardial infarction and regional ventricular performance using technetium-99m hexakis (t-butylisonitrile) technetium (I) (TBI): a new myocardial imaging agent

Technetium-99m hexakis (t-butylisonitrile) technetium (I) (99mTc-TBI) is a new myocardial perfusion imaging agent. To determine its potential in the evaluation of myocardial infarction, 15 patients with suspected or confirmed acute infarction were studied by bedside imaging in the coronary care unit. Good-quality planar scintigrams in multiple projections were obtained in 13 patients. Gated perfusion studies were performed in 14 patients, and for comparison 13 of these were restudied 24-72 h later by standard gated equilibrium blood pool radionuclide ventriculography. Conventional and planar scintigraphic criteria for myocardial infarction (acute or old) agreed in 12 (92%) patients (k = 0.81, p less than 0.05). All the infarctions detected by scintigraphy were associated with electrocardiographic Q-waves. Localization of infarction by the electrocardiogram and scintigraphy exhibited moderate agreement (k = 0.49, p less than 0.1). Regional wall motion analysis by standard radionuclide ventriculography and gated 99mTc-TBI scintigraphy were in complete agreement for 25 (64%) of 39 left ventricular segments (k = 0.35, p less than 0.05). However, in 7 other segments, associated with areas of infarction, regional wall motion abnormalities were noted only on gated 99mTc-TBI scintigraphy. Therefore, 99mTc-TBI scintigraphy can readily provide data on regional myocardial perfusion and wall motion, permitting detection and localization of areas of myocardial infarction. The superior imaging properties, ready availability and low cost of 99mTc point to the considerable potential value of 99mTc-TBI in assessing patients with suspected or confirmed myocardial infarction.     

111In-antimyosin scintigraphy on acute myocardial infarction]

Indium-111 antimyosin (InAM) scintigraphy was performed in 17 patients with acute myocardial infarction (on 15 +/- 6 days from the onset). The degree of myocardial uptake was classified into 3 groups. They were ranged from low intensity as in bone marrow to high intensity as in liver. All of 17 cases showed positive myocardial uptake including low intensity. The locations of infarction judged by InAM were in agreement with those by electrocardiography, coronary angiography (CAG), and 99mTc-pyrophosphate scintigraphy (PYP, performed on 5 +/- 2 days from the onset). In 5 cases, the uptake of InAM showed doughnuts or diffuse pattern which was occasionally observed on PYP. These cases showed myocardial uptake of 4th degree of Parkey's classification with doughnuts-like pattern on PYP, and showed involvement of left anterior descending artery on CAG. In some cases, the extent of myocardial uptake on InAM did not agree with those on PYP.     

Detection and size estimation of acute myocardial infarction using 99Tc-glucoheptonate.

Twenty-seven patients with suspected acute myocardial infarction were studied by precordial scanning after intravenous administration of 99mTc-gluchoheptonate 2-48 hr after the onset of chest pain. Fifteen of the patients had clinically documented acute myocardial infarctions. Twelve of these 15 (80%) had areas of distinctly increased tracer uptake in the region of the heart. The three infarctions not identified by scan had peak serum CPK values of less than 300. In seven patients without infarction, no distinct areas of increased tracer uptake were found in the region of the heart. Five patients could not be classified as to whether infarction had or had not occurred. Three had abnormal scans, the significance of which is uncertain. Infarct size was estimated from the area of increased 99mTc-glucoheptonate concentration on scan and compared to peak serum CPK values. A linear correlation with a correlation coefficient of 0.77 was found. Technetium-99-m-glucoheptonate scanning was useful for the identification and size estimation of moderate- to large-size transmural and nontransmural acute myocardial infaractions.     

Myocardial perfusion at fatal infarction: location and size of scintigraphic defects.

In a consecutive study of myocardial scintigraphy in acute ischemic syndrome, four patients had 99mTc-hexamibi injected intravenously before they developed fatal cardiogenic shock. Planar scintigraphy was performed after death. Slices of the hearts after autopsy were analyzed for scintigraphic and pathoanatomic abnormalities. Location of perfusion defects in planar views of the heart was in good agreement with the scintigraphied, sliced sections. The extent of infarction judged from inspection and formasan staining was much smaller (7%-40% and 6%-43% of the total slice area) than found at scintigraphy, where 83%-92% of the myocardium showed ischemia as defined by a 99mTc-hexamibi uptake below an arbitrary limit on half maximum uptake. Myocardial hypoperfusion might thus aggravate the functional impairment at myocardial infarction and lead to cardiogenic shock.     

Acute myocardial infarct imaging with indium-111-labeled monoclonal antimyosin Fab

Indium-111 monoclonal antimyosin Fab scintigraphy was used to detect myocardial necrosis in 52 of 54 patients (96.3%) with acute myocardial infarction. Infarcts were visualized when coronary arteries were persistently occluded (n = 10), became patent after thrombolysis (n = 33), or became patent after spontaneous reperfusion (n = 7). Posteroinferolateral visualizations were obtained in two patients with clinical and enzymatic evidence of infarction but normal electrocardiograms. Of the two patients in whom no infarcts were visualized, one had an anterior myocardial infarct. This patient underwent successful thrombolytic therapy, with attendant minimization of creatine kinase release. The other patient had a small, nonreperfused inferior myocardial infarct. Five patients with a history of remote infarction and acute necrosis showed antimyosin uptake only in regions concordant with the acute episodes of infarction, and radiolabeled antimyosin Fab localized in neither old infarcts nor normal, noninfarcted myocardium. Antimyosin Fab scintigraphy, thus, appears to be a highly specific means of delineating necrotic myocardium, at least in this limited and selected group of patients.     

In vivo detection of cell death in the area at risk in acute myocardial infarction.

Annexin A5 is a phospholipid binding protein with high affinity for phosphatidyl-serine, which is externalized by cells undergoing programmed cell death. An increased programmed cell death rate has been reported in the heart after myocardial infarction (MI). The aim of this study was to correctly localize annexin A5 uptake in vivo and to determine the area at risk in humans with acute MI. METHODS: Nine patients were studied. Before reperfusion was achieved, (99m)Tc-sestamibi was injected intravenously. Myocardial (99m)Tc-sestamibi perfusion scintigraphy was performed after reperfusion. Thereafter, (99m)Tc-labeled annexin A5 was administered intravenously, followed by scintigraphic imaging of the heart. Myocardial (99m)Tc-sestamibi scintigraphy was repeated 1-3 wk after the MI onset. (99m)Tc-Annexin uptake was also studied in the subacute phase of the MI in 2 patients. RESULTS: All patients clearly showed perfusion defects on (99m)Tc-sestamibi scintigraphy in concordance with the infarct location. Furthermore, all patients showed accumulation of (99m)Tc-annexin A5 at the infarct site, indicating that cardiomyocytes with externalized phosphatidyl-serine are present in the infarct area. (99m)Tc-sestamibi defects determined 1-3 wk after the MI onset were significantly smaller than the defects in the acute phase. (99m)Tc-annexin uptake was absent in the 2 patients studied in the subacute phase. CONCLUSION: In acute MI, an increase of programmed cell death can be correctly localized in vivo in the area at risk. Furthermore, the decrease in (99m)Tc-sestamibi defect size in the subacute phase of the MI further suggests that in parts of the area at risk, reversible myocardial damage rather than necrosis is present in cardiomyocytes.     

The scintigraphic evaluation of myocardial infarction and regional ventricular performance using technetium-99m hexakis (t-butylisonitrile) technetium (I) (TBI): A new myocardial imaging agent

Technetium-99m hexakis (t-butylisonitrile) technetium (I) (^99mTc-TBI) is a new myocardial perfusion imaging agent. To determine its potential in the evaluation of myocardial infarction, 15 patients with suspected or confirmed acute infarction were studied by bedside imaging in the coronary care unit. Good-quality planar scintigrams in multiple projections were obtained in 13 patients. Gated perfusion studies were performed in 14 patients, and for comparison 13 of these were restudied 24–72 h later by standard gated equilibrium blood pool radionuclide ventriculography. Conventional and planar scintigraphic criteria for myocardial infarction (acute or old) agreed in 12 (92%) patients (k=0.81, p<0.05). All the infarctions detected by scintigraphy were associated with electrocardiographic Q-waves. Localization of infarction by the electrocardiogram and scintigraphy exhibited moderate agreement (k=0.49, p<0.1). Regional wall motion analysis by standard radionuclide ventriculography and gated ^99mTc-TBI scintigraphy were in complete agreement for 25 (64%) of 39 left ventricular segments (k=0.35, p<0.05). However, in 7 other segments, associated with areas of infarction, regional wall motion abnormalities were noted only on gated ^99mTc-TBI scintigraphy. Therefore, ^99mTc-TBI scintigraphy can readily provide data on regional myocardial perfusion and wall motion, permitting detection and localization of areas of myocardial infarction. The superior imaging properties, ready availability and low cost of ^99mTc point to the considerable potential value of ^99mTc-TBI in assessing patients with suspected or confirmed myocardial infarction.This work was done during the tenure of a British-American Research Fellowship of the American Heart Association and the British Heart Foundation, with Dr. S. Campbell the recipient     

Rapid and accurate diagnosis of acute cholecystitis with 99mTc-HIDA cholescintigraphy.

Technetium-99m dimethyl acetanilide iminodiacetic acid (HIDA) cholescintigraphy was performed on 90 patients with suspected acute cholecystitis. Visualization of the gallbladder established patency of the cystic duct and excluded the diagnosis of acute cholecystitis in 50 of 52 patients. Nonvisualization of the gallbladder with visualization of the common bile duct was diagnostic of acute cholecystitis in 38 patients, all subsequently proven at surgery. The observed accuracy of this procedure is 98% and specificity is 100%. The false negative rate is 5% and false positive rate is zero. Technetium-99m-HIDA has many advantages which make it the procedure of choice in evaluating a patient for suspected acute cholecystitis. It is a rapid, simple, safe examination which provides functional as well as anatomic information about the hepatobiliary system in individuals with a serum bilirubin level up to 8 mg/100 ml.     

Prognostic value of myocardial salvage achieved by reperfusion therapy in patients with acute myocardial infarction.

Myocardial salvage assessed by (99m)Tc-sestamibi scintigraphy is a marker of myocardial tissue reperfusion in patients with acute myocardial infarction. The prognostic value of myocardial salvage index in patients with acute myocardial infarction after reperfusion therapy has not, however, been investigated. METHODS: We analyzed 765 patients with acute myocardial infarction randomized to treatment by coronary stenting (383 patients), primary coronary angioplasty (251 patients), or thrombolysis (131 patients) in the setting of 3 randomized trials. Initial (before reperfusion therapy) and follow-up (7-14 d after reperfusion therapy) scintigraphic examinations were performed to assess the initial perfusion defect, final infarct size, and salvage index. Patients were categorized into 2 groups defined by the median salvage index (0.5): the group with salvage index < 0.5 (374 patients) and the group with salvage index >or= 0.5 (391 patients). The primary endpoint of the study was mortality at 6 mo after the index event. RESULTS: Six-month mortality was 5.1% (19 deaths) in the group with salvage index < 0.5, compared with 1.0% (4 deaths) in the group with salvage index >or= 0.5 (odds ratio, 5.1; 95% confidence interval, 1.9-13.3; P = 0.001). Salvage index (median [25th, 75th percentiles] was significantly smaller in nonsurvivors than in survivors (0.19 [0.05, 0.37] vs. 0.50 [0.26, 0.80], P = 0.0004). The Cox proportional hazards model showed that myocardial salvage index (P = 0.0007), initial perfusion defect (P = 0.0007), and age (P = 0.04) were independently associated with 6-mo mortality. CONCLUSION: Myocardial salvage achieved by reperfusion therapy predicts mortality in patients with acute myocardial infarction. Our findings support the use of salvage index as a surrogate of mortality in clinical trials designed to test the efficacy of reperfusion therapies among patients with acute myocardial infarction.     

Edema is a sign of early acute myocardial infarction on post-mortem magnetic resonance imaging

The aim of this study was to investigate if acute myocardial infarction can be detected by post-mortem cardiac magnetic resonance (PMMR) at an earlier stage than by traditional autopsy, i.e., within less than 4 h after onset of ischemia; and if so, to determine the characteristics of PMMR findings in early acute infarcts. Twenty-one ex vivo porcine hearts with acute myocardial infarction underwent T2-weighted cardiac PMMR imaging within 3 h of onset of iatrogenic ischemia. PMMR imaging findings were compared to macroscopic findings. Myocardial edema induced by ischemia and reperfusion was visible on PMMR in all cases. Typical findings of early acute ischemic injury on PMMR consist of a central zone of intermediate signal intensity bordered by a rim of increased signal intensity. Myocardial edema can be detected on cardiac PMMR within the first 3 h after the onset of ischemia in porcine hearts. The size of myocardial edema reflects the area of ischemic injury in early acute (per-acute) myocardial infarction. This study provides evidence that cardiac PMMR is able to detect acute myocardial infarcts at an earlier stage than traditional autopsy and routine histology.     

Detection of acute myocardial infarction by 99mTc-labeled D-glucaric acid imaging in patients with acute chest pain.

Definitive diagnosis of acute myocardial infarction early in the process is often difficult. An imaging agent that localized quickly and specifically in areas of acute necrosis could provide this critical diagnostic information. To determine whether imaging with 99mTc-labeled D-glucaric acid (GLA) could provide this information, we imaged a group of patients presenting with symptoms suggestive of acute infarction. METHODS: Twenty-eight patients presenting to the emergency department with symptoms highly suggestive of acute infarction were injected with 99mTC-GLA and imaged about 3 h later. RESULTS: The sensitivity of lesion detection was remarkably time dependent. Fourteen patients with acute infarction injected within 9 h of onset of chest pain had positive scans, even in the presence of persistent occlusion. The remaining 14 patients had negative scans. Nine patients with negative scans had acute infarction but were injected more than 9 h after onset of chest pain. The final diagnosis in the remaining 5 patients was unstable angina (3 injected <9 h and 2 injected >9 h after onset of chest pain). Six patients were reinjected with 99mTc-GLA 4-6 wk after their initial study to determine whether persistent positive scans occurred with this agent. All 6 had negative scans. CONCLUSION: This study suggests that 99mTc-GLA localizes in zones of acute myocardial necrosis when injected within 9 h of onset of infarction.     

Indium-111-antimyosin antibody imaging for detecting different stages of myocardial infarction: comparison with technetium-99m-pyrophosphate imaging

The diagnostic value of 111In-antimyosin (AM) imaging for identifying myocardial infarction was evaluated in comparison with 99mTc-pyrophosphate (PPi) imaging. Twenty-four patients with various stages of myocardial infarction, ranging from three days to nine months after the onset of infarction, underwent both AM and PPi scans. Of 26 infarct lesions AM scan identified 22 (85%), while PPi scans detected 10 (38%) (p less than 0.01). When less than a week had passed since the onset both scans demonstrated all infarct lesions. For seven subacute lesions studied within one to two weeks of onset, AM scans detected (100%), while PPi scans identified only 2 (29%). Furthermore, AM scans showed discrete myocardial uptake in 7 (64%) of those studied more than two weeks after onset. The intensity of AM uptake in the infarcts studied more than seven days after onset was less than that in acute infarcts studied within seven days of onset (p less than 0.05). These preliminary data indicate that the abnormal myocardial uptake of AM persists beyond the first two weeks when PPi no longer accumulates. Thus, AM scans can be considered to provide a sensitive diagnosis of subacute as well as acute myocardial necrosis.     

Value of magnetic resonance imaging in patients with a recent myocardial infarction: Comparison with planar thallium-201 scintigraphy

The diagnostic accuracy of spin-echo Magnetic Resonance (MR) imaging in the detection and localization of a recent myocardial infarction (mean 4 days old) was compared to planar thallium-201 scintigraphy in 20 patients with a documented myocardial infarction. A control group of 10 subjects underwent a similar MR imaging procedure without thallium-201 scintigraphy. T1-weighted MR images (TE 30 msec) showed abnormal thinning of the infarcted left ventricular wall during systole (<50% of the opposite wall) in 11 patients (55%). On T2-weighted multi-echo MR images, (TE 30–60–90–120 msec) abnormally increased signal intensity was found in 17 patients and coincided with the location of the infarction. Thallium-201 scintigraphy detected the infarction in 18 patients. Comparison of T2-MR imaging and thallium-201 scintigraphy showed concordant findings in 82% of the left ventricular segments. In 9% of segements, thallium uptake was reduced with normal T2-MR and in 9% we found a normal thallium uptake with abnormal T2-MR findings. In all subjects of the control group, T1-MR images were normal, and only one subject showed increased signal intensity on T2-MR images. We conclude that the diagnostic accuracy of MR imaging in detecting a myocardial infarction is similar to that of T1-201 scintigraphy.     

Impact of myocardial perfusion imaging on clinical management and the utilization of hospital resources in suspected acute coronary syndromes

Recent advances in the treatment of acute coronary syndromes has raised awareness in the community that prompt presentation for chest pain may be life saving. Each year in the United States, more than 6 million people present to the hospital with an acute chest pain, making this the most common presenting chief complaint second only to abdominal pain. Most patients presenting with chest discomfort have a non-ischaemic electrocardiogram on presentation. However, these patients are routinely admitted to hospital due to diagnostic uncertainty for occult myocardial infarction or ischaemia. As an approach to this dilemma, many hospitals have created protocols as a means of facilitating the identification of infarction and ischaemia and the safe and effective triage of patients with a chief complaint of chest pain. Myocardial perfusion imaging at rest has been shown to be highly sensitive for the detection of acute myocardial infarction, and can be supplemented with provocative testing after infarction has been excluded. Diagnostic strategies that utilize myocardial perfusion imaging for the evaluation of acute chest pain have successfully improved the triage of these patients by avoiding inadvertent discharge of patients with myocardial infarctions, and reducing unnecessary hospital admissions and overall cost and expenditure.     

Time course of myocardial infarction evaluated by indium-111-antimyosin monoclonal antibody scintigraphy: clinical implications and prognostic value.

To investigate the clinical implications of 111In-antimyosin antibody scintigraphy in the chronic stage of myocardial infarction, 34 studies were performed in 26 patients with 36 infarcts of various infarct ages. The infarcts were divided into three groups according to time from onset of chest pain to scintigraphy. Positive antimyosin images were obtained in 93% of Group I patients (3 days to 1 mo), 71% of Group II patients (1.5 mo to 1 yr) and none were obtained from Group III patients (1.5-6 yr). A negative correlation was observed between antimyosin uptake and the time after myocardial infarction. In Group II, patients with coronary artery patency and patients showing redistribution on exercise 201TI scintigraphy were more likely to have positive antimyosin images compared to patients without these features. Recurrent angina may also relate to chronic antimyosin uptake. Indium-111-antimyosin antibody scintigraphy may be a useful method in assessing the course of myocardial infarction and for the patient follow-up.