Myocardial kinetics of technetium-99m-hexakis-2-methoxy-2-methylpropyl-isonitrile (original) (raw)
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Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1993
Technetium-99m-teboroxime (CardioTec) is a promising new myocardial perfusion imaging agent. The purposes of this study were to define teboroxime clearance kinetics in normal and flow-restricted myocardium over a 1-hr period and to determine whether teboroxime kinetics are useful in detecting myocardial hyperperfusion. Accordingly, the circumflex arteries of 23 dogs were stenosed. By using miniature cadmium-telluride radiation detectors, myocardial teboroxime activities were continuously monitored in both the control and the stenosed zones. Myocardial clearance of teboroxime was modeled and found to be biexponential over 1 hr. A significant difference in myocardial clearance between the normal and stenosed zones (t1/2 = 4.5 +/- 0.9 min versus 10.2 +/- 2.6 min, respectively; p < 0.05) was observed for the first exponential phase (the first 5 min following initial uptake), but not for the second exponential phase (t1/2 = 160.7 +/- 35.9 min versus 140.4 +/- 27.4 min, respectively; p...
Myocardial imaging with technetium-99m CPI: initial experience in the human
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1987
The hexakis(isonitrile)technetium(I) analog [99mTc]carbomethoxyisopropyl isonitrile (CPI) has high myocardial uptake and rapid lung and liver clearance in most animal species. To evaluate [99mTc]CPI as a myocardial imaging agent in the human, we evaluated this tracer in three normals and in six patients with coronary artery disease (CAD). In normals, [99mTc]CPI cleared quickly from the lungs and accumulated in the liver and heart. The liver activity peaked at 10-15 min and cleared through the hepatobiliary system. Planar images were of excellent technical quality with high myocardial to background ratios as early as 10 min after injection. Myocardial activity fell gradually to 76.1 +/- 2.9 (s.d.)% of initial activity by 60 min after injection. In six patients with CAD, myocardial defects were present on planar images up to 2 hr after exercise and injection. In one out of six patients, the defect was not seen 3 hr after injection. In five of the six patients, normal perfusion pattern...
Myocardial clearance kinetics of technetium-99m-SQ30217: a marker of regional myocardial blood flow
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1990
SQ30217 is a new, technetium-99m-(99mTc) labeled perfusion agent introduced for cardiac imaging. To evaluate the myocardial tracer kinetics, 99mTc-SQ30217, was injected intracoronarily in open-chested dogs under baseline conditions and after administration of intravenous (i.v.) dipyridamole. Myocardial first-pass retention fraction averaged 0.90 +/- 0.04. Clearance of the tracer occurred in a biexponential manner. Sixty-seven percent of retained activity cleared with a half-time of 2.3 +/- 0.6 min, while the residual activity demonstrated slow clearance. The clearance rate of the rapid phase correlated with myocardial blood flow (r = 0.72, p less than 0.001). Myocardial SQ30217 clearance rate following i.v. injection as determined by dynamic imaging with tomography (SPRINT) averaged 21 +/- 4 min and increased to 13 +/- 4 min following dipyridamole. Thus, 99mTc-SQ30217 is a promising flow tracer with high initial myocardial retention and rapid tissue clearance, which allow repeated f...
Journal of Nuclear Medicine
T he studyof myocardial perfusion with @°‘Tl has be come indispensable duringcoronary artery disease (CAD) evaluation, whether as a diagnostic tool or in the prognosis of such disease (1â€"3). Some of the disadvantages of @°‘Tl, such as cyclotron production, low photon energy and long half-life,which limitsthe allowabledose (4), have favored the development of technetium agents for perfusion imag ing. To date, three technetium compounds have demon strated their clinical utility: sestamibi (5), teboroxime (6) and tetrofosmin (7), but none has totally supplanted @°‘Tl, which remains the most commonly used tracer. This is partly due to the fact that @°@Tl is used both as a tracer of regional blood coronary flow distribution and as a marker of myocardial cellular viability, while technetium com plexes are pure blood flow tracers. This characteristic of 20111 is related to its redistribution.
Myocardial uptake and kinetic properties of technetium-99mQ3 in dogs
Journal of Nuclear Medicine
-ethylenebis(acetylacetoneimin ato)bis(tris(3-methoxy-l-propyl)phosphine), also known as @Tc-Q3, produces prompt myocardial visualization with rapidhepatic clearance in humans (1,2). As a result of the higher physical energy of @â€oeTc compared to @°‘Tl, it is likely that @Tc-Q3 could provide myocardial images with less image degradationby soft tissue attenuationcompared to 20111. If @Tc-Q3 is confirmed to have more rapid he patic clearance in humans compared to the clinically avail able @â€oeTc myocardial tracer, sestamibi, the time from tracer injection to the beginningof imagingcould be short ened without significantinterferencefrom hepatic activity.
Evaluation in dogs and humans of three potential technetium-99m myocardial perfusion agents
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1986
The biodistribution of the three cationic 99mTc complexes [99mTc(TMP)6]+, [99mTc(POM-POM)3]+, and [99mTc(TBIN)6]+--where TMP represents trimethylphosphite, POM-POM represents 1,2-bis(dimethyoxyphosphino)ethane, and TBIN represents t-butylisonitrile--have been evaluated in humans and dogs. Each agent was studied in three normal volunteers at rest, while [99mTc(POM-POM)3]+ and [99mTc(TBIN)6]+ were each studied in one normal volunteer at exercise. Even though all three agents yield good myocardial images in dogs, none appear suitable for clinical use as myocardial perfusion imaging radiopharmaceuticals. In humans, [99mTc(TMP)6]+ and [99mTc(POM-POM)3]+ clear very slowly from the blood and provide myocardial images only several hours after injection. [99mTc(TBIN)6]+ clears rapidly from the blood, but accumulation in the lung obscures the myocardial image for the first hour after injection; at later times, activity in the liver and spleen masks the apical wall. These results correlate wit...
Perfusion and Specific Radioprobes for Cardiac Imaging
2013
Major advancements have been made in treating cardiovascular disease. However, improving diagnosis is crucial, because the detection of the early stages of disease would allow preventative approaches therapy. Myocardial perfusion imaging is in clinical use for decades and is an effective tool for diagnosis, and longterm follow-up of patients with suspected or known coronary artery disease. The technetium-based agents, 99mTc-sestamibi and 99mTc-tetrofosmin, are widely used myocardial blood flow tracers. However, since both present drawbacks in their biodistribution properties, there is now resurgence in the study of both neutral and cationic technetium agents to further improve the characteristics of perfusion radiopharmaceuticals. Despite all the success of perfusion imaging, a unique strength of nuclear imaging is its ability to provide tools for imaging processes at molecular and cellular levels in intact organisms under a wide variety of physiologic conditions. Advances in new specific imaging agents that identify myocardium injury and cellular dysfunction may contribute to the improvement of diagnosis and eventually better therapeutic approaches. In this communication, we will review perfusion agents and their biological mechanism of uptake. We will also discuss examples of target-specific radiopharmaceuticals for cardiac imaging, including advances in pre-clinical imaging approaches.