Myocardial infarct imaging with 99mTc-pyrophosphate and 99mTc-methylene diphosphonate: lack of correlation.

A prospective study of eight patients with recent transmural myocardial infarction was performed using 99mTc-Sn-pyrophosphate and 99mTc-Sn-methylene diphosphonate in each patient. All pyrophosphate scans were strongly positive whereas the diphosphonate scan was strongly positive in only one case. We conclude that 99mTc-Sn-pyrophosphate is preferable to 99mTc-Sn-methylene diphosphonate for myocardial imaging.     

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.     

Emission tomography with 99mTc-pyrophosphate in the diagnosis of acute myocardial infarction

Electrocardiograms (ECG) and enzyme criteria are usually used to confirm the diagnosis of acute myocardial infarction in the case of chest pain. However, ECG is not always diagnostic. Elevated enzyme values may be due to causes other than myocardial infarction. In uncertain cases, the ECG and enzyme criteria can be supplemented by emission tomography, performed with technetium pyrophosphate that will accumulate in the site of infarction. Twenty-nine patients with suspected acute myocardial infarction were studied with emission tomography. Of these 12 had acute transmural infarction. Both enzyme tests and ECG were diagnostic in only 7 of these 12 cases, 4 had positive enzyme tests but a nondiagnostic ECG and in one case neither enzymes nor ECG were diagnostic. In 11 patients the infarcted myocardial area was detected with emission tomography. Six patients had acute nontransmural infarction. Only 2 of these had positive emission tomography. The chest pain was not due to infarction in 11 patients. All these patients had negative emission tomography. The sensitivity of emission tomography was 92% and specificity 100% in transmural acute infarction. In nontransmural infarction the specificity was only 33%. Emission tomography is a valuable diagnostic tool. It may be the decisive method when ECG and enzymes are not diagnostic. Emission tomography also shows the localization and size of the infarcted area in the myocardium.     

Myocardial localization of 99mTc-pyrophosphate without evidence of acute myocardial infarction.

Localization of 99mTc-pyrophosphate in the cardiac region during routine bone scanning for metastatic tumor is discussed in two cases. Clinical information as well as electrocardiographic and serum enzyme studies did not reveal any evidence of acute myocardial injury. The cause of myocardial localization of the radiopharmaceutical is not clear in these cases.     

Improvement of 99mTc-pyrophosphate scintigraphy in detection of acute myocardial infarction: combined with 99mTc-tetrofosmin]

BACKGROUND: 201Tl and 99mTc-pyrophosphate (PYP) dual scintigraphy is daily used in the detection of acute myocardial infarction (AMI). However, 201Tl is not available on emergent situation. We proposed a new method for detection of AMI combined 99mTc-PYP with 99mTc-tetrofosmin (TF). METHODS: 99mTc-PYP (740 MBq) was administered to 25 patients with AMI, and 3.5 hours later, planar imaging (PYP planar) and SPECT were performed (PYP-SPECT). Immediately after cessation of PYP-SPECT, 99mTc-TF (370-740 MBq) was injected and 5 minutes later SPECT was performed in the same position (TF-SPECT). PYP-SPECT and TF-SPECT were reconstructed in the same geometric status to permit superimpose of PYP-SPECT and TF-SPECT images. Two experts and 2 beginners of nuclear medicine physician interpreted the images in three ways; PYP planar image only, PYP-SPECT, and PYP-SPECT with TF-SPECT. RESULTS: PYP-SPECT combined with TF-SPECT shows 100% detectability of the AMI lesions, which is significantly higher than other two methods in both experts and beginners. CONCLUSION: PYP-SPECT combined with TF-SPECT is a powerful method for detection of AMI.     

Clinical evaluation of 99mTc-pyrophosphate myocardial emission computed tomography: comparison with planar imaging

To depict the three-dimensional distribution of 99mTc-pyrophosphate in the heart, emission computed tomography (ECT) was performed, following the conventional planar imaging, in 32 cases with suspected acute myocardial infarction (AMI). There were 23 cases with evidence of AMI, 7 with unstable angina (UA), and 2 with dilated cardiomyopathy (DCM). While the planar images showed discrete cardiac activity in only 11 of the 23 cases (48%) with AMI, the ECT images delineated focal myocardial uptake clearly in 20 of them (87%). On the other hand, the ECT images revealed cardiac blood-pool activity without significant myocardial uptake in all cases with UA and DCM in which the planar images showed diffuse activity. Thus, the ECT imaging of 99mTc-pyrophosphate seems to be a valuable technique for assessing the presence and localization of myocardial necrosis, especially in cases showing diffuse cardiac activity in the planar imaging.     

Clinical evaluation of 99mTc-pyrophosphate myocardial emission computed tomography: Comparison with planar imaging

To depict the three-dimensional distribution of ^99mTc-pyrophosphate in the heart, emission computed tomography (ECT) was performed, following the conventional planar imaging, in 32 cases with suspected acute myocardial infarction (AMI). There were 23 cases with evidence of AMI, 7 with unstable angina (UA), and 2 with dilated cardiomyopathy (DCM). While the planar images showed discrete cardiac activity in only 11 of the 23 cases (48%) with AMI, the ECT images delineated focal myocardial uptake clearly in 20 of them (87%). On the other hand, the ECT images revealed cardiac blood-pool activity without significant myocardial uptake in all cases with UA and DCM in which the planar images showed diffuse activity. Thus, the ECT imaging of ^99mTc-pyrophosphate seems to be a valuable technique for assessing the presence and localization of myocardial necrosis, especially in cases showing diffuse cardiac activity in the planar imaging.     

Evaluation of renal ischemia with 99mTc-pyrophosphate

Renal ischemia injury was induced by transient 30-min occlusion of the main renal artery in five rabbits and by transient 60-min occlusion in four rabbits. The vessels to the contralateral kidneys were ligated in all nine animals and in six additional control rabbits. Renal blood flow was restored immediately following the transient ischemia. Twenty-four hours later, ^99mTc-pyrophosphate was injected and renal uptake was monitored for 100 s at 10-min intervals for 90 min following injection. At 90 min postinjection, the animals were killed and the percent injected dose remaining in the kidneys was calculated for three animals in each group. At 60 min postinjection, in vivo activity in the 30-min ischemic kidneys was 2.3 times greater than that of controls, and activity in the 60-min ischemic kidneys 4.6 times greater than that of controls. These results suggest that ^99mTc-pyrophosphate scanning may be useful in assessing slight ischemic damage to the kidney.     

Soft-tissue uptake of 99mTc-diphosphonate and 99mTc-pyrophosphate in amyloidosis

This study describes the results of scintigraphy with 99mTc-labeled methylene-diphosphonate (99mTc-MDP) and pyrophosphate (99mTc-PYP) as a noninvasive test for the distribution of organ involvement in five different types of amyloidosis. Scintigraphy with 99mTc-labeled phosphates appeared to be a sensitive noninvasive screening test for the extent and the distribution of organ involvement in systemic AA and systemic AL amyloidosis as well as in local bronchial amyloid, local dermal amyloid, and familial amyloidotic polyneuropathy. Echocardiography, however, was more sensitive for demonstrating cardiac involvement in systemic amyloidosis than 99mTc-MDP or 99mTc-PYP scintigraphy. 99mTc-MDP images showed a better contrast than 99mTc-PYP images, although there was no difference in the extent or the intensity of soft-tissue uptake.     

Soft-tissue uptake of99m-Tc-diphosphonate and99mTc-pyrophosphate in amyloidosis

This study describes the results of scintigraphy with^99mTc-labeled methylene-diphosphonate (^99mTc-MDP) and pyrophosphate (^99mTc-PYP) as a noninvasive test for the distribution of organ involvement in five different types of amyloidosis. Scintigraphy with^99mTc-labeled phosphates appeared to be a sensitive noninvasive screening test for the extent and the distribution of organ involvement in systemic AA and systemic AL amyloidosis as well as in local bronchial amyloid, local dermal amyloid, and familial amyloidotic polyneuropathy. Echocardiography, however, was more sensitive for demonstrating cardiac involvement in systemic amyloidosis than^99mTc-MDP or^99mTc-PYP scintigraphy.^99mTc-MDP images showed a better contrast than^99mTc-PYP images, although there was no difference in. the extent or the intensity of soft-tissue uptake.     

Evaluation of renal ischemia with 99mTc-pyrophosphate

Renal ischemia injury was induced by transient 30-min occlusion of the main artery in five rabbits and by transient 60-min occlusion in four rabbits. The vessels to the contralateral kidneys were ligated in all nine animals and in six additional control rabbits. Renal blood flow was restored immediately following the transient ischemia. Twenty-four hours later, 99mTc-pyrophosphate was injected and renal uptake was monitored for 100 s and 10-min intervals for 90 min following injection. At 90 min postinjection, the animals were killed and the percent injected dose remaining in the kidneys was calculated for three animals in each group. At 60 min postinjection, in vivo activity in the 30-min ischemic kidneys was 2.3 times greater than that of controls, and activity in the 60-min ischemic kidneys 4.6 times greater than that of controls. These results suggest that 99mTc-pyrophosphate scanning may be useful in assessing slight ischemic damage to the kidney.