Myocardial scintigraphy with 99mTc-tris-DMPE in man

Cardiac scintigraphy was performed in six patients with a documented previous myocardial infarction, in one patient with mitral regurgitation, and in four healthy volunteers following administration of 99mTc-tris-DMPE. An intense early blood pool phase permitted gated blood pool scintigraphy and left ventricular ejection fraction calculation. A myocardial phase 12-14 h later permitted myocardial perfusion imaging. The rest myocardial perfusion image quality with 99mTc-tris-DMPE appeared to be superior to the resting image quality obtained with 99mTc-dichloro-DMPE but was inferior to the resting image quality obtained with 201Tl.     

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.     

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     

Clinical significance of denervated but viable myocardium in patients with recanalized acute myocardial infarction.

In patients with acute myocardial infarction (MI), myocardial sympathetic innervation evaluated by 123I-metaiodobenzylguanidine myocardial scintigraphy is more sensitive to ischaemia than the associated perfusion abnormality of 201Tl myocardial scintigraphy. The purpose of this study was to evaluate the scintigraphic indices related to the recovery of left ventricular function after acute MI. 123I-metaiodobenzylguanidine and 201Tl-chloride imaging were performed in 15 patients (mean age 60 years, 13 men and 2 women) 2 weeks after the onset of acute MI. Using a 20-segment visual interpretation of the 201Tl image, myocardial segments were classified into persistent defect, redistribution or reverse redistribution, and normal 201Tl uptake. The extent of denervated segments showed a fair correlation with the ejection fraction on admission (r = -0.53, P = 0.04), whereas the extent of persistent defect had a close correlation with the ejection fraction at 4 months (r = -0.79, P = 0.01). There was a good correlation between the extent of denervated but viable myocardium and the change in ejection fraction from admission to 4 months (r = 0.68, P = 0.01). Thus, denervated but viable myocardium is a scintigraphic index related to the functional recovery of left ventricular pump function after acute MI.     

Prognostic value of stress Tc-99m tetrofosmin SPECT in patients with previous myocardial infarction: Impact of scintigraphic extent of coronary artery disease

BACKGROUND: Our objective was to assess the prognostic value of the scintigraphic extent of coronary artery disease on stress technetium 99m tetrofosmin single photon emission computed tomography in patients with previous myocardial infarction. METHODS AND RESULTS: We studied 383 patients (280 men and 103 women; mean age, 60 +/- 11 years) more than 3 months after an acute myocardial infarction by exercise bicycle or dobutamine (up to 40 mug . kg -1 . min -1 ) stress Tc-99m tetrofosmin myocardial perfusion tomography. Stress images were acquired 1 hour after stress, and rest images were acquired 24 hours after stress testing. An abnormal study was defined as one demonstrating a reversible or fixed perfusion abnormality. Myocardial segments were assigned to corresponding coronary arteries as follows: the apex, anterior wall, and anterior septum were assigned to the left anterior descending coronary artery; the posterolateral wall was assigned to the left circumflex artery; and the basal posterior septum and inferior wall were assigned to the right coronary artery. During a mean follow-up of 4.3 +/- 2.1 years, 48 cardiac events occurred (36 cardiac deaths and 12 nonfatal myocardial infarctions). Myocardial perfusion was normal in 51 patients, abnormal in a single-vessel distribution in 170 patients, and abnormal in a multivessel distribution in 162 patients. The annual cardiac event rates in these groups were 0.4%, 2.6%, and 4%, respectively. In a multivariate analysis model, independent predictors of cardiac events were diabetes mellitus (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.4-4.5), history of congestive heart failure (OR, 2.7; 95% CI, 1.4-4), age (OR, 1.05; 95% CI, 1.01-1.08), and scintigraphic extent of coronary artery disease (OR, 4.2; 95% CI, 1.8-9.1). CONCLUSION: Stress Tc-99m tetrofosmin myocardial perfusion imaging provides independent prognostic information for the risk stratification of patients with previous myocardial infarction. The event rate is directly related to the scintigraphic extent of coronary artery disease. Patients with normal perfusion have an excellent event-free survival rate.     

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.     

Nuclear medicine in the diagnosis of cardiac contusion

In 16 patients with blunt trauma to the chest, the role of cardiovascular nuclear medicine was evaluated using anterior chest flow assessment, with first-pass ejection fraction of left and right ventricles and 99mTc-pyrophosphate scintigraphy. The radiopharmaceutical used was pyrophosphate, labelled with approximately 20 mCi 99mTc. The anterior chest flow and first-pass ejection fractions were initially obtained during the injection of 99mTc-pyrophosphate and were followed up 3 h later by anterior, LAO 45 degrees, and left lateral views of the chest, using an LFOV gamma camera with a data processor. The results were compared with serial cardiac enzymes studies, electrocardiograms and echocardiograms. Of the patients, 77% showed scintigraphic evidence of cardiac contusion. The intensity of activity varied from grades I to II; five patients had abnormal echocardiographic findings. Only two had abnormal ejection fractions, and one patient had evidence of left ventricular aneurysm along with poor ventricular performance. Cardiac enzymes were found to be the least helpful. Electrocardiograms, though non-specific for myocardial damage, were abnormal in 62% of the patients. Eleven of our patients had both abnormal ECG and increased PYP uptake. Even though there is no agreement as to which noninvasive parameter is more sensitive in the diagnosis of myocardial contusion, 99mTc-pyrophosphate scintigraphy, in conjunction with ECG, seems promising in this respect.     

CT imaging features and frequency of left ventricular myocardial fat in patients with CT findings of chronic left ventricular myocardial infarction

AIM: To determine the frequency of left ventricular myocardial fat in patients with computed tomography (CT) findings of chronic left ventricular myocardial infarction, and to review the typical CT imaging features. MATERIALS AND METHODS: A retrospective search of the CT and nuclear scintigraphy reports from 1998-2005 for chronic left ventricular myocardial infarction was performed. The study group comprised those cases with available CT examinations revealing findings of chronic left ventricular myocardial infarction. Assessment for the presence of various imaging characteristics of left ventricular myocardial fat was performed in all cases. RESULTS: The frequency of left ventricular myocardial fat in 47 patients with CT evidence of chronic left ventricular myocardial infarction was 51%. Typical CT imaging features include thin linear or curvilinear fat attenuation within left ventricular myocardium, most commonly subendocardial, often associated with left ventricular wall thinning and/or calcification, predominantly in elderly men. CONCLUSIONS: Fat in the left ventricular myocardium is a common additional finding in patients with CT findings of chronic left ventricular myocardial infarction. The potential, but as yet unproven, use of this CT imaging finding is that the radiologist may be able to suggest a potential diagnosis of chronic left ventricular myocardial infarction on unenhanced, thick-section, non-gated or non-triggered chest CT imaging where identification of myocardial wall thinning may be difficult.     

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.     

Simultaneous assessment of right ventricular function and hypertrophy by Tc-99m MIBI

PURPOSE: Tc-99m MIBI allows the simultaneous performance of cardiac blood pool scintigraphy and myocardial SPECT. The authors performed studies to determine whether right ventricular function and hypertrophy can be evaluated simultaneously using Tc-99m MIBI in patients with right heart disease. METHODS: Using right heart catheterization, several parameters of pulmonary circulation were measured, including right ventricular ejection fraction, in 23 patients with chronic pulmonary disease and pulmonary vascular disease. Within 1 week, right heart blood pool scintigraphy was performed using the first-pass method using Tc-99m MIBI. The right ventricular ejection fraction calculated from right heart blood pool scintigraphy was compared with that measured using right heart catheterization. Myocardial SPECT was performed 1 hour after right heart blood pool scintigraphy. On the short axis images, which allowed optimal visualization of the right ventricle, the right and left ventricular free walls were established as regions of interest. Myocardial wall counts were determined. The right ventricular uptake: left ventricular uptake ratio was calculated to study the relation of that ratio to mean pulmonary artery pressure and total pulmonary resistance. RESULTS: A significant correlation was observed between the right ventricular ejection fraction calculated on right heart catheterization and that calculated on right heart blood pool scintigraphy. The right ventricular uptake:left ventricular uptake ratio correlated positively with pulmonary artery pressure and total pulmonary resistance. CONCLUSION: These results suggest that Tc-99m MIBI allows simultaneous noninvasive evaluation of cardiac function and structure, which previously was considered impossible in patients with right heart disease.     

A new method to evaluate ischemic heart disease: Combined use of rest thallium-201 myocardial SPECT and Tc-99m exercise tetrofosmin first pass and myocardial SPECT

We developed a new diagnostic method for simultaneously evaluating myocardial ischemia, myocardial viability and ventricular function in less than 90 minutes by combined use of rest thallium-201 (Tl) SPECT and exercise Tc-99m tetrofosmin (TF) first pass and SPECT. The subjects were 9 healthy controls, 19 angina pectoris patients, and 19 old myocardial infarction patients, in all of whom coronary angiography had been performed. Rest Tl myocardial SPECT was performed first, and was followed by exercise TF myocardial SPECT. We also performed first pass radionuclide angiography by TF during maximum exercise on a bicycle ergometer to assess the left ventricular ejection fraction (LVEF). The total examination time was less than 90 minutes. SPECT diagnosis was performed by semi-quantitative analysis. LVEF below 55% was regarded as abnormal. In the patients with angina pectoris, analysis according to the coronary artery showed that the diagnostic accuracy of SPECT was 85.0% for ischemia in the region of the left anterior descending branch (LAD), 87.5% for the left circumflex branch (LCX) and 77.8% for the right coronary artery (RCA). The accuracy of diagnosis for angina pectoris was 82.1%, as determined by SPECT alone, and rose to 89.3% when the LVEF levels were also taken into consideration. In the patients with old myocardial infarction, the diagnostic accuracy of SPECT was 84.2% for the LAD, 92.3% for the LCX and 85.0% for the RCA. Analysis by patients showed that the accuracy of diagnosis for myocardial infarction was 85.7%, as determined by SPECT alone. The diagnostic accuracy, however, rose to 89.3% when the LVEF levels also were taken into consideration. In conclusion, it was demonstrated that this combined diagnostic method was highly reliable for evaluating ischemic heart disease within a short time.     

Assessment of therapeutic effect in acute myocardial infarction using early/delayed images of 123I-BMIPP myocardial scintigraphy

This study was aimed at analyzing the discordance between the initial and late scintigraphic images in patients with acute myocardial infarction (AMI), and utilizing the data obtained for the treatment of AMI patients. Ninety-one patients with a history of the first episode of AMI were enrolled as subjects for this study. Emergency coronary angiography was performed in all the patients and left ventriculography (LVG) was carried out subsequently. 123I-BMIPP myocardial scintigraphy was performed to obtain initial images (BMi) and delayed images at 4 hours (BMd). Scintigraphy was performed a mean of 6 days after the onset of AMI in the patients. The subjects were classified into three groups according to the scintigraphic data. Quantitative gated single photon emission computed tomography (SPECT) with 99mTc-sestamibi (MIBI) was also conducted one month and 6 months later in all the patients. Discordance was observed in 51% of the patients. Left ventricular volume based on the quantitative gated SPECT (QGS) data at one month and 6 months after myocardial scintigraphy was significantly smaller in the washout group than in the other two groups. There was no significant change in LV volume measured at 6 months as compared to that measured at one month in the washout group. Significant increases in LVEDVI and LVESVI were observed over time in the no discordance group. In the fill-in group, the LV volume at one month was significantly higher than that in the washout group, but no significant change with time was observed. During the subacute stage of myocardial infarction, discordance is often seen between initial and late BMIPP-myocardial-scintigraphic images. The presence of such discordance, and analysis of its pattern, may be useful in predicting the cardiac function in these patients during the chronic phase of this disease.     

Usefulness of 18F-FDG PET for diagnosis of cardiac sarcoidosis]

Cardiac sarcoidosis, the main cause of death among patients with sarcoidosis, frequently becomes clinically apparent when the disease is far advanced. To evaluate the usefulness of the 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in detecting cardiac sarcoidosis, 18F-FDG PET was performed in 16 patients with sarcoidosis (13 female, 63 +/- 12 yrs), compared with scintigraphic findings of 99mTc-MIBI and 67Ga. Ten of 16 patients were considered to have cardiac complications on clinical grounds with tissue confirmation such as positive endomyocardial biopsy, severe ventricular arrhythmia, more than second degree atrioventricular block, and echocardiographically proven ventricular dysfunction. Among these patients with cardiac complications, abnormal myocardial uptake of FDG were observed in all (100%), which confirms significantly higher frequency compared to 67Ga scintigraphy (50%) (abnormality of 99mTc-MIBI SPECT were observed in 80%). Although abnormal FDG accumulations were observed in region with decreased uptake of 99mTc-MIBI in many cases, localization of regional abnormality of each tracer was frequently independent. This discrepancy may reflect inflammatory and degenerative process of myocardium in cardiac sarcoidosis. 18F-FDG PET is thought to be a useful noninvasive method in detecting cardiac involvement of sarcoidosis and may provide a useful information on the activity of the disease.     

Nuclear medicine in the diagnosis of cardiac contusion

In 16 patients with blunt trauma to the chest, the role of cardiovascular nuclear medicine was evaluated using anterior chest flow assessment, with first-pass ejection fraction of left and right ventricles and ^99mTc-pyrophosphate scintigraphy. The radiopharmaceutical used was pyrophosphate, labelled with approximately 20 mCi^99mTc. The anterior chest flow and first-pass ejection fractions were initially obtained during the injection of ^99mTc-pyrophosphate and were followed up 3 h later by anterior, LAO 45°, and left lateral views of the chest, using an LFOV gamma camera with a data processor. The results were compared with serial cardiac enzymes studies, electrocardiograms and echocardiograms. Of the patients, 77% showed scintigraphic evidence of cardiac contusion. The intensity of activity varied from grades I to II; five patients had abnormal echocardiographic findings. Only two had abnormal ejection fractions, and one patient had evidence of left ventricular aneurysm along with poor ventricular performance. Cardiac enzymes were found to be the least helpful. Electrocardiograms, though non-specific for myocardial damage, were abnormal in 62% of the patients. Eleven of our patients had both abnormal ECG and increased PYP uptake. Even though there is no agreement as to which noninvasive parameter is more sensitive in the diagnosis of myocardial contusion, ^99mTc-pyrophosphate scintigraphy, in conjunction with ECG, seems promising in this respect.     

Active inflammatory bowel disease: head-to-head comparison between 99mTc-hexamethylpropylene amine oxime white blood cells and 99mTc(V)-dimercaptosuccinic acid scintigraphy

PURPOSE: Evaluation and comparison between pentavalent 99mTc dimercaptosuccinic acid (99mTc(V)-DMSA) and 99mTc-hexamethylpropylene amine oxime white blood cell (99mTc-HMPAO WBC) scintigraphy in the detection and assessment of disease activity in patients with active inflammatory bowel disease (IBD). MATERIALS AND METHODS: 99mTc(V)-DMSA scintigraphy was performed in 23 patients with active IBD and true positive 99mTc-HMPAO WBC scintigraphy. Images were considered positive when an area of increased uptake was observed. To assess severity of IBD, semi-quantitative analysis was included with reference to the uptake in the iliac crest. Comparison with endoscopic, radiological and clinical data was performed. RESULTS: The diagnostic accuracy of 99mTc-HMPAO WBC and 99mTc(V)-DMSA was 91% and 84%, respectively. A significant correlation between the findings of both radioisotopic methods and scintigraphy score was demonstrated. Endoscopic findings were significantly correlated with scintigraphic results. Kappa statistics showed a moderate to good agreement between the two scintigraphic methods. Two patients (8.8%) had negative findings with 99mTc(V)-DMSA scintigraphy (false negative results). CONCLUSION: 99mTc(V)-DMSA compared to 99mTc-HMPAO WBC could provide a simple, non-invasive alternative method for the assessment of disease activity, although it is slightly inferior to 99mTc-HMPAO WBC scintigraphy especially in the evaluation of disease localization in IBD patients.     

Early detection of left ventricular mural thrombi after acute Q wave myocardial infarction using 111In oxine-labelled autologous platelets

Autologous 111In oxine-labelled platelet scintigraphy was used to detect left ventricular thrombi in 20 patients with anterior and 18 patients with inferior Q wave myocardial infarction within 48-72 h. Left ventricular thrombi were found in 8/20 patients with anterior myocardial infarction and in 1/18 patients with inferior myocardial infarction, giving a total incidence of 24%. Patients with left ventricular thrombi were older (64.3 versus 58.2 years), had higher peak creatinine kinase (CK) levels (4523 versus 2749 IU 1-1), lower ejection fraction (19.5 versus 37.8%, P less than 0.005) and were more likely to have an enlarged left ventricle than those without left ventricular thrombi (87.5 versus 54.5%, P less than 0.001). Left ventricular thrombi were found overlying sites of myocardial infarction in 8 out of 9 patients. Apical left ventricular thrombi were 1.7 times more common than septal left ventricular thrombi. All patients received minidose heparin for prevention of deep venous thrombosis. This technique is complementary to echocardiography and may provide additional information in the difficult cases where the decision about full-dose anticoagulation is in doubt.     

Adenosine technetium-99m sestamibi single-photon emission tomography for the assessment of jeopardized myocardium early after acute myocardial infarction

This study investigated the value of technetium-99m sestarnibi scintigraphy in identifying patients at risk for post-infarct ischaemia (=jeopardized myocardium), especially within the reperfused infarct region. In 51 patients with a recent (99mTc-sestamibi single-photon emission tomography (SPET) and dobutamine stress echocardiography (DSE) were performed and correlated with the presence of significant coronary artery stenosis [% diameter stenosis (DS) >50%] on quantitative coronary angiography. Regional perfusion activity was analysed semiquantitatively (score 0–4) on a 13-segment left ventricular model. DSE was used for the estimation of the infarct size (low-dose DSE) and for concomitant evaluation of ischaemia (high-dose DSE). A reversible perfusion defect within the infarct region was observed in 20 of the 37 patients with a significant infarct-related lesion (sensitivity of 54%) and only in one patient without a significant infarct-related lesion (specificity of 93%). Further analysis revealed that the scintigraphic assessment of jeopardized myocardium was fairly good in patients with a moderate (DS 51%–64%) infarct-related stenosis but was inadequate in patients with a severe (DS65%) infarct-related stenosis (sensitivity of 80% vs 36%,P<0.01), while the echocardiographic detection of ischaemia was not influenced by stenosis severity (sensitivity of 73% in both subgroups). This scintigraphic under-estimation of jeopardized myocardium was mainly related to a severely impaired myocardial perfusion under baseline conditions, as was evidenced by a significantly more severe rest perfusion score in the infarct region in patients with a severe stenosis as compared to those with a moderate stenosis (average score: 1.5±0.7 vs 2.1±0.6,P<0.01), while infarct size on echocardiography was similar for both subgroups. It may be concluded that early after an acute myocardial infarction, adenosine^99mTc-sestamibi SPET may underestimate reperfused but still jeopardized myocardium, particularly in patients with a severe infarct-related stenosis. In these patients the evaluation of the ischaemic burden on rest-stress scintigraphy is hampered by the presence of a severely impaired myocardial perfusion in resting conditions.     

99mTc-MIBI (RP-30) to define the extent of myocardial ischemia and evaluate ventricular function

99mTc-MIBI, a new myocardial perfusion agent, is a technetium labeled isonitrile derivative. We have taken advantage of the physical characteristics of 99mTc to combine at rest, post infarction, ventricular function studies with analysis of perfusion. We have studied at rest and at stress, 22 patients with coronary artery disease selected on the basis of an abnormal coronary angiogram or on the basis of a positive exercise ECG stress test for symptomatic angina. We have also studied, at rest only, 20 patients with a previous myocardial infarction. A comparative thallium planar scintigraphy was obtained for all patients. The sensitivity of 99mTc-MIBI scintigraphy for detecting individual vessel lesions at stress was 88% as compared with 83% for 201Tl. Sensitivity was higher in patients with previous myocardial infarction (93% for the 2 isotopes) than in patients without (85% for 99mTc-MIBI versus 81% for 201Tl). Segmental myocardial correspondence between 99mTc-MIBI and 201Tl was very close (92%). The overall sensitivity for the detection of acute myocardial infarction reached respectively 91% for 99mTc MIBI and 87% for 201Tl. The specificity in the regions corresponding to arteries not involved was excellent for both tracers as we did not observe any false positive result. This is important information but it does not correspond to the specificity to detect coronary artery disease in the overall patient population. The correlation between first pass left ventricular ejection fraction obtained with 99mTc-MIBI and equilibrium left ventricular ejection fraction obtained with 99mTc red cells was excellent (r = 0.96). It was not as good but was still satisfactory for the right ventricle (r = 0.75).(ABSTRACT TRUNCATED AT 250 WORDS)     

Accuracy of 99mTc-tetrofosmin myocardial tomography in the evaluation of coronary artery disease

BACKGROUND: Technetium 99m-labeled myocardial agents have been proposed as an alternative to thallium 201. The aim of this study was to assess retrospectively the accuracy of exercise myocardial 99mTc-tetrofosmin scintigraphy with tomographic imaging (SPECT) in a large group population in the evaluation of coronary artery disease. Furthermore we evaluated the relation between the severity of scintigraphic impaired myocardial perfusion and the angiographic coronary artery stenoses in patients without myocardial infarction and with stenosis localized exclusively in the proximal segment of the 3 main coronary arteries. METHODS AND RESULTS: The study group consisted of 235 consecutive patients, 204 (87%) of whom were men, with a mean age of 57+/-10 years, and with suspected or known coronary artery disease, who underwent 99mTc-tetrofosmin SPECT and coronary angiography. Furthermore, 61 patients in a low-likelihood group for coronary artery disease were also studied. Significant disease was defined by > or = 50% luminal coronary artery stenosis in > or = 1 native coronary artery or major branch or in a saphenous vein graft or arterial mammary graft. The overall sensitivity was 95%, specificity was 76%, and predictive accuracy was 95%. The normalcy rate for the low-likelihood group was 93%. Sensitivity was 71% for the left anterior descending artery, 61% for the left circumflex artery, and 73% for the right coronary artery. Specificity was 94% for the left anterior descending artery, 96% for the left circumflex artery, and 91% for the right coronary artery. Predictive accuracy was 79% for the left anterior descending artery, 78% for the left circumflex artery, and 81 % for the right coronary artery. In patients without myocardial infarction linear regression analysis between scintigraphy and angiography showed a significant correlation in patients with severe proximal coronary artery stenosis (r = 0.53, P < .002), but not in those with moderate proximal stenosis (r = 0.31, P = NS). CONCLUSIONS: This study shows that 99mTc-tetrofosmin SPECT is accurate in the detection of coronary artery disease. The relation of the severity of scintigraphic impaired myocardial perfusion and angiographic coronary artery stenosis, however, may differ significantly in patients with proximal stenosis of different severity.     

Phase and amplitude imaging in the diagnosis of acute right ventricular damage in inferior infarction

Right ventricular infarction is not uncommon in patients with inferior myocardial infarcts. Phase and amplitude analysis of equilibrium gated cardiac blood pool studies is useful in documenting right ventricular damage complicating left ventricular infarction. In 15 of 37 patients with acute inferior infarction, right ventricular extension of the infarct was demonstrated by this approach, complementing the findings of infarct avid imaging with Tc-99m pyrophosphate (Tc-99m PYP).