Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TECHNETIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65Linked to original sources
PubMed1993

Assessment of perfused left ventricular mass in normal, ischemic, and reperfused myocardium by means of single-photon emission computed tomography of technetium-99m isonitrile.

To test the hypothesis that single-photon emission tomography of technetium (Tc) 99m hexakis 2-methoxyisobutyl isonitrile (Tc-MIBI) can accurately measure perfused left ventricular (LV) mass in nonischemic, ischemic, and reperfused myocardium, we acquired Tc-MIBI tomographic images in canines with normally perfused hearts (n = 33) after occlusion of the left anterior descending coronary artery (n = 15), after reperfusion (n = 13), and with subsequent second injection of Tc-MIBI (15 to 18 mCi; n = 12). In all ischemic studies the initial dose of Tc-MIBI (5 to 6 mCi) was injected after coronary artery occlusion but before reflow. Scintigraphic perfused LV mass was calculated from the total voxels demonstrating Tc-MIBI uptake x voxel volume (cm3) x specific gravity of myocardium (1.05 gm/cm3). After being imaged the animals were killed, the left ventricle was weighed, and the risk area was determined by dual perfusion with phthalocyanine blue dye and triphenyltetrazolium chloride (TTC). Perfused LV mass was defined as total LV mass minus the risk area mass. There was good correlation between scintigraphic and morphologic determinations of perfused left ventricular mass in nonischemic hearts (Tc-MIBI left ventricular distribution = 0.84 x left ventricular weight + .20.4, n = 33, r = 0.93, p = 0.0001) and ischemic hearts (Tc-MIBI left ventricular distribution = 0.51 x left ventricular weight + 37.9, n = 15, r = 0.83, p = 0.0001). In animals imaged both before and after reperfusion, scintigraphic determinations of the nonischemic region correlated closely (after-reflow Tc-MIBI distribution = 1.07 x before-reflow Tc-MIBI distribution--8.0, n = 13, r = 0.88, p = 0.0001), indicating that Tc-MIBI does not significantly redistribute into the ischemic zone after reperfusion. After injection of the second dose of Tc-MIBI in acutely reperfused canines, there was good correlation between the distribution mass of Tc-MIBI and the mass of viable myocardium by TTC staining (Tc-MIBI distribution = 0.61 x viable LV mass + 34.2, n = 12, r = 0.77, p = 0.0001). Furthermore, the apparent redistribution of myocardial Tc-MIBI from before and after second injection images correlated with the degree of myocardial salvage by histochemical staining (r = 0.72, p = 0.0082). In conclusion, single-photon emission computed tomography of Tc-MIBI can measure perfused LV mass accurately in both ischemic and nonischemic canine preparations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Simultaneous assessment of left ventricular perfusion and function with technetium-99m sestamibi after coronary artery bypass grafting.

This study examined the left ventricular perfusion and EF by using simultaneous SPECT and first-pass radionuclide angiography with technetium 99m sestamibi in 95 patients after uncomplicated coronary artery bypass grafting. The patients were divided into those with normal EF and no previous myocardial infarction before surgery (group 1, n = 57), and those with abnormal EF or infarction (group 2, n = 38). The SPECT images were normal in 37 patients in group 1 and in 6 patients in group 2 (p < 0.0001). The patients with normal SPECT images had a higher EF after surgery than those with abnormal images (65% +/- 10% vs 50% +/- 14%, p < 0.0001) and was higher in group 1 than in group 2 (64% +/- 8% vs 46% +/- 16%, p < 0.0001). There was a significant correlation between the EF and the extent of perfusion abnormality (r = -0.44, p < 0.0001). The patients with normal SPECT images could not be separated from those with abnormal images based on peak CK, CK-MB, and the electrocardiographic changes. Of the 69 patients with postoperative EF > or = 50%, the perfusion pattern was normal in 41 and abnormal in 28; of the 26 patients with EF < 50%, 24 had abnormal SPECT (p < 0.003). There was no significant change in mean EF after surgery (55% +/- 14% before vs 56% +/- 15% after). Thus simultaneous assessment of left ventricular perfusion and function after coronary artery bypass grafting showed that an abnormal perfusion pattern may exist despite a normal EF. These patients could not be predicted by enzymes or electrocardiographic changes.

Aged↗
PubMed1994

Prevalence of right ventricular perfusion defects after inferior myocardial infarction assessed by low-level exercise with technetium 99m sestamibi tomographic myocardial imaging.

To assess the prevalence of right ventricular perfusion defects after a recent inferior wall myocardial infarction, 33 patients were studied 6 to 14 days after infarction with low-level exercise testing and technetium 99m (99mTc) sestamibi (SPECT) imaging. Twenty-two control subjects with a < 5% likelihood of coronary artery disease undergoing exercise 99mTc sestamibi imaging were also studied. For each image the right ventricle was computer isolated from reconstructed transverse cardiac slices, followed by reorientation into oblique slices. Both right and left ventricular images were visually assessed for defects. A quantitative method of defect detection was also applied to the right ventricle. For the right ventricle, 100% of the stress images and 96% of the rest images were adequate for interpretation. Right ventricular stress perfusion defects were identified in 10 (30%) of 33 patients with recent inferior infarction, with 50% completely or partially normalizing on rest images, consistent with ischemia. Of 14 patients with left ventricular inferoseptal defects, eight (57%) had right ventricular defects compared with 2 (11%) of 19 without inferoseptal defects (p < 0.005). We concluded that the right ventricle can be adequately assessed for perfusion defects by means of exercise with 99mTc sestamibi SPECT imaging. Defects of the right ventricle after inferior myocardial infarction occur frequently, and many have evidence of ischemia. Right ventricular perfusion defects are closely associated with left ventricular inferoseptal defects.

Case-Control Studies↗
PubMed1995

Prognostic value of predischarge dipyridamole technetium 99m sestamibi myocardial tomography in medically treated patients with unstable angina.

Recently developed unstable angina clinical practice guidelines have recommended risk stratification with dipyridamole thallium-201 myocardial imaging in patients at "intermediate" pretest clinical risk who cannot exercise maximally. The prognostic value of predischarge dipyridamole technetium 99m sestamibi (MIBI) tomography has not been assessed in this clinical setting. To this end, 128 medically treated patients with unstable angina at intermediate pretest clinical risk underwent follow-up for 16 +/- 11 (mean +/- SD) months after predischarge intravenous dipyridamole MIBI tomography. An abnormal MIBI scan result was present in 99 patients (77%), of whom 47 had one or more reversible and 76 had one or more fixed perfusion defects. Cardiac events occurred in 68 (53%) patients after dipyridamole testing: recurrent unstable angina (n = 36), nonfatal acute myocardial infarction (n = 6), or death (n = 26). A cardiac event occurred in 10% of patients with normal MIBI tomography results compared with 69% of those with abnormal results (p < 0.01). Event rates associated with specific perfusion defects were similar (reversible = 68%; fixed = 71%) and were greater than rates in patients without defects (both p < 0.05). Clinical variables associated with increased risk of cardiac events by univariate analysis included a history of congestive heart failure, prior myocardial infarction, and diabetes mellitus (all p < 0.05). Independent multivariable predictors (Cox proportional hazards model) of any cardiac event were an abnormal result of MIBI scan (relative risk [RR] = 4.3, 95% confidence interval [CI] 1.5 to 12.0) and a reversible (RR = 1.8, 95% CI 1.1 to 2.9) or a fixed perfusion defect (RR = 2.9, 95% CI 1.6 to 5.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Angina, Unstable↗
PubMed1975

Myocardial imaging with indium- 113m- and technetium-99m-macroaggregated albumin. New procedure for identification of stress-induced regional ischemia.

Regional coronary blood flow distribution was studied by myocardial imaging after intracoronary injection of technetium-99m- and indium-113m-macroaggregated albumin at rest and during coronary hyperemia induced by intracoronary injection of Hypaque-M, 75 percent. The four- to five-fold increase in coronary flow after injection of radiographic contrast material was similar in magnitude to that occurring with maximal exercise stress. Experimentally, resting coronary blood flow and regional distribution of radioactive particles remains normal in spite of coronary stenosis of up to 85 percent. Less severe stenosis causes flow and distribution abnormalities only during periods of increased flow, and the degree of maldistribution is directly related to the physiologic severity of the stenosis. Of 49 patients with suspected coronary artery disease, 10 had no significant lesions by coronary arteriography and all had normal images at rest and during coronary hyperemia. Thirty-seven of 39 patients with significant obstructive coronary artery disease had abnormal images at rest or during contrast agent-induced hyperemia, or both. Patients with significant coronary artery disease without previous infarction usually demonstrated abnormalities in flow distribution only during coronary hyperemia. Patients with previous infarction demonstrated resting perfusion abnormalities that often became more abnormal during hyperemia. This technique provides a new method for assessing the physiologic effects of coronary stenosis in conjuntion with coronary arteriography.

Albumins↗
PubMed1975

Detection of acute myocardial infarction by technetium-99m polyphosphate.

Experimental work has shown that technetium-99m (99mTc) pyrophosphate accumulates in recently infarcted myocardium and can be detected by external imaging techniques. Twenty-two 99mTc polyphosphate myocardial studies were performed in 17 patients (in 3 after cardiac surgery) 3 to 20 days after myocardial infarction. Seventeen myocardial studies were performed in 17 control patients (in 6 after cardiac surgery). Twenty millicuries of 99mTc polyphosphate was injected intravenously 60 to 120 minutes prior to gamma camera imaging in several views. Myocardial images were processed by the Gamma-11 computer system using standardized background subtraction and contrast enhancement. Results of 16 myocardial studies performed 4 to 20 days after transmural myocardial infarction in 12 patients were positive in 13 instances and questionable in 1. The location of the myocardial infarction by imaging corresponded to location by standard electrocardiograhic criteria in 8 of the 10 patients with positive findings. In five patients with nontransmural myocardial infarction, results of myocardial imaging were positive in two, questionable in one and normal in one. In one patient with questionable findings results were normal when imaging was repeated 16 days after nontransmural myocardial infarction. Results of 17 control myocardial imaging studies were normal in 16 and questionable in 1. Therefore, 99mTc polyphosphate myocardial imaging appears promising in the detection and location of transmural myocardial infarction. Its accuracy in detecting nontransmural myocardial infarction may be increased with greater experience and development of sophisticated digital analysis techniques. The method may prove useful in clinical situations such as cardiac surgery in which standard diagnostic aids are difficult to interpret.

Acute Disease↗
PubMed1976

Improved detection of myocardial infarction with technetium-99m stannous pyrophosphate and serum MB creatine phosphokinase.

The relative sensitivity and combined value of myocardial technetium-99m stannous pyrophosphate imaging and determinations of serum MB creatine phosphokinase (the "myocardial" CPK isoenzyme) in detecting acute myocardial infarction were evaluated in 41 patients with suspected infarction and 23 patients recovering from cardiac surgery. In the patients with suspected infarction, myocardial infarction was confirmed in 25 and was consistently associated with increased serum MB CPK. Abnormal radionuclide images were obtained in 23 of 25 patients (92 percent) with definite myocardial infarction and in 2 of 16 patients without confirmed infarction. Although the localization of infarction by imaging correlated well with the localization by electrocardiogram, infarct size estimated by imaging did not correlate well with estimates based on peak total serum CPK activity or serial changes in CPK activity. Serum MB CPK activity increased after cardiac surgery in 6 patients undergoing valve replacement and in 17 patients undergoing coronary arterial bypass surgery. However, no patient with valve replacement and only 1 of the 17 with bypass surgery had an abnormal radionuclide image. These results suggest that (1) abnormal radionuclide images in patients without infarction can be distinguished from abnormal images indicative of ischemic necrosis by consideration of MB CPK activity and (2) interpretation of elevated MB CPK activity, particularly in particularly in patients undergoing cardiac surgery, is facilitated by evaluation with imaging.

Adult↗
PubMed1977

Technetium-99m pyrophosphate myocardial uptake in patients with stable angina pectoris.

99m-technetium (Tc) pyrophosphate myocardial scintigrams of 55 patients with stable angina pectoris were compared with those of 13 normal subjects. The mean scintigraphic score, obtained by averaging the blinded interpretations of four readers scoring on an integral scale from 0 to 4, was significantly higher for the patients with angina than for the control subjects (1.36 compared with 0.48, P less than 0.001). Among the patients with angina, those who had a prior myocardial infarction had a higher mean scintigraphic grade than those without a previous infarction (1.73 versus 1.15, P less than 0.005), and the mean grade in both groups was higher than that of control subjects (P less than 0.001). Radionuclide uptake was predominantly diffuse in the patients with angina pectoris (70%), although in those with greater uptake accumulation tended to be localized. Three of the 68 subjects had high levels of radionuclide uptake but no clinical evidence of acute myocardial injury. This study demonstrates that excess myocardial accumulation of 99m-Tc pyrophosphate can occur in patients with stable angina pectoris.

Angina Pectoris↗
PubMed1978

Prevalence of right ventricular involvement in inferior wall infarction assessed with myocardial imaging with thallium-201 and technetium-99m pyrophosphate.

To assess the prevalence and clinical relevance of right ventricular involvement in acute inferior wall infarction, 78 consecutive patients with the latter condition were studied with thallium-201 and technethium-99m pyrophosphate myocardial imaging. Right ventricular involvement was determined from superimposition of the 45 degree left anterior oblique thallium-201 and technetium-99m pyrophosphate images. All 78 patients shoed thallium-201 defects. Sixty-four patients had positive pyrophosphate scans, and 24 of these (37.5 percent) showed right ventricular involvement. None of the patients with right ventricular involvement in this consecutive series showed the classic signs of severe right ventricular failure, although subclinicalright ventricular dysfunction may have been present. There was no significant difference in the incidence of cardiogenic shock between the groups with and without right ventricular involvement. It is concluded that right ventricular involvement in acute inferior wall infarction is relatively frequent but not necessarily associated with severe right-sided pump failure. In patients with acute inferior wall infarction and severe pump failure, dual imaging provides a simple nonivasive method of identifying the subgroup of patients with right ventricular involvement who may benefit from volume loading.

Adult↗
PubMed1980

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 death or both, before hospital discharge. Approximately 95 percent of patients with transmural or nontransmural myocardial infarction can be detected with technetium-99m pyrophosphate 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.

Acute Disease↗
PubMed1990

Experimental studies of the physiologic properties of technetium-99m isonitriles.

Recently, efforts have been directed at the development of technetium-99m (Tc-99m)-labeled isonitrile compounds for assessment of regional perfusion and viability after experimental myocardial infarction or ischemia. One of the most promising of these agents, Tc-99m sestamibi, has undergone rather extensive laboratory investigation. Like thallium-201 (Tl-201), the uptake of Tc-99m sestamibi in myocardial tissue is proportional to myocardial blood flow after intravenous injection. Similar to other diffusible indicators, Tc-99m sestamibi underestimates blood flow at high flow rates. In low flow regions, the myocardial uptake of this agent is higher relative to nonischemic uptake than is microsphere-determined blood flow. This is attributed to increased extraction at low flows. This first-pass myocardial extraction fraction for Tc-99m sestamibi is less than that for Tl-201. However, Tc-99m sestamibi has a higher parenchymal cell permeability and higher volume of distribution than T;-201. Tc-99m sestamibi shows minimal "delayed redistribution" after initial intravenous administration. Uptake of Tc-99m sestamibi is not altered by myocardial "stunning" or with ischemic dysfunction produced by sustained low coronary flow. The uptake of the isonitrile is still proportional to blood flow in these situations. In intact animal models, myocardial uptake of Tc-99m sestamibi during coronary occlusion delineates the in vivo area at risk. When Tc-99m sestamibi is administered after reperfusion following variable periods of preceding coronary occlusion, Tc-99m sestamibi uptake delineates the area of viable myocardium that is salvaged and not simply the degree of reflow. This suggests that serial Tc-99m sestamibi imaging might be useful in assessing the efficacy of coronary reperfusion after thrombolytic therapy.

Animals↗
PubMed1990

Technical aspects of myocardial planar imaging with technetium-99m sestamibi.

Fundamental quantitative planar imaging techniques, evolved over the years, have been adapted to maximize the efficiency and clinical effectiveness of technetium-99m (Tc-99m) sestamibi imaging. To ensure reproducible image interpretation, the Society for Motion Picture and Television Engineers test pattern is used to obtain the necessary standardization of video and hard copy images. A standardized intensity scale intuitively relates count density to perceived brightness. Data are accumulated via standard 16-frame multiple gated acquisition and can be viewed in cine mode to assess wall motion. The images are then automatically summed for quantitative analysis of myocardial perfusion. Excessive extracardiac Tc-99m activity is automatically suppressed by the computer program to prevent suboptimal display of the heart. Due to the difference in heart background ratio and shape of the extracardiac background between resting and exercise Tc-99m sestamibi images, a modified interpolative background subtraction algorithm was developed. Image registration is necessary for accurate comparison of the rest and exercise images to detect redistribution. This is automatically accomplished by adjusting the position of the background-subtracted and centered images so as to maximize the cross-correlation coefficient. Profiles are generated to sample the myocardial count distribution and can be compared to a normal database, subject to confirmation by a competent interpreter. Rest redistribution is defined by a change in the myocardial distribution of Tc-99m sestamibi between exercise and rest images. Flashback display is used to identify subtle regions of redistribution that often signify residual viability within an infarct zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart↗
PubMed1990

Technical aspects of myocardial SPECT imaging with technetium-99m sestamibi.

Most reports to date using single photon emission computed tomography (SPECT) with technetium-99m (Tc-99m) sestamibi have used acquisition parameters that were optimized for thallium-201. To fully utilize the superior imaging characteristics of Tc-99m sestamibi, there is a need to optimize the technical aspects of SPECT imaging for this agent. Performance can be enhanced through the careful selection of optimal radiopharmaceutical doses, imaging sequences, acquisition parameters, reconstruction filters, perfusion quantification methods and multidimensional methods for visualizing perfusion distribution. The current report describes theoretical considerations, phantom studies and preliminary patient results that have led to optimized protocols, developed at Emory University and Cedars-Sinai Medical Center, for same-day rest-stress studies, given existing instrumentation and recommended dose limits. The optimizations were designed to fit a low-dose-high-dose rest-stress same-day imaging protocol. A principal change in the acquisition parameters compared with previous Tc-99m sestamibi protocols is the use of a high-resolution collimator. The approach is being developed in both prone and supine positions. A new method for extracting a 3-dimensional myocardial count distribution has been developed that uses spherical coordinates to sample the apical region and cylindrical coordinates to sample the rest of the myocardium. New methods for visualizing the myocardial distribution in multiple dimensions are also described, with improved 2-dimensional, as well as 3- and 4-dimensional (3 dimensions plus time) displays. In the improved 2-dimensional display, distance-weighted and volume-weighted polar maps are used that appear to significantly improve the representation of defect location and defect extent, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Graphics↗
PubMed1990

Detection and location of myocardial infarction using technetium-99m sestamibi imaging at rest.

Technetium-99m (Tc-99m) sestamibi imaging at rest has been used to detect and localize myocardial infarction. The largest study to date is a cooperative study of 146 patients in 17 institutions. There were 24 normal subjects and 122 patients with documented myocardial infarction based on clinical, enzymatic or electrocardiographic criteria. The presence of segmental myocardial perfusion defects was compared to the presence of a Q wave on the electrocardiogram or wall motion abnormality on gated blood pool scans, performed within 48 hours of the Tc-99m sestamibi study. Of the 122 infarct patients, 118 (97%) showed perfusion abnormalities by Tc-99m sestamibi imaging. A perfusion defect was found in 110 (99%) of 111 patients with a Q wave and a wall motion abnormality, 113 (99%) of 114 patients with a wall motion abnormality and 113 (98%) of 115 patients with a Q wave. Of the 24 normal subjects, 22 (92%) had normal Tc-99m sestamibi images. In 75% of 1,986 segments, both a Tc-99m sestamibi defect and a regional wall motion abnormality on gated blood scans were present. In 11% of segments, wall motion was normal but Tc-99m sestamibi imaging was abnormal; in 14% of segments, wall motion was abnormal and Tc-99m sestamibi images were normal. In the 24 control subjects, 99% of the segments were normal. Thirty-eight patients had coronary angiography. A close relation existed between the coronary anatomy and myocardial Tc-99m sestamibi uptake. All 9 territories supplied by an occluded vessel and poor collaterals had grade 0 uptake (scale 0 to 2: 0 = markedly reduced; 2 = normal).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Thrombolytic therapy for myocardial infarction: assessment of efficacy by myocardial perfusion imaging with technetium-99m sestamibi.

Technetium-99m (Tc-99m) sestamibi has been used to evaluate the efficacy of thrombolytic therapy. Improved image quality due to the higher photon energy of Tc-99m and the increased allowable doses of this radiopharmaceutical along with its lack of redistribution makes Tc-99m sestamibi an acceptable imaging agent for such studies. This imaging agent was used for serial quantitative planar and tomographic imaging to assess the initial risk area of infarction, its change over time and the relation to infarct-related artery patency in patients with a first acute myocardial infarction. Twenty-three of 30 patients were treated with recombinant tissue-type plasminogen activator (rt-PA) within 4 hours after onset of acute chest pain. Seven patients were treated in the conventional manner and did not receive thrombolytic therapy. The initial area at risk varied greatly both in patients treated with rt-PA and in those who received conventional therapy. Patients with successful thrombolysis and patient infarct arteries had a significantly greater reduction of Tc-99m sestamibi defect size than patients who had persistent coronary occlusion. Serial imaging with Tc-99m sestamibi could find important application in future clinical research evaluating the efficacy of new thrombolytic agents. Direct measurements of the amount of hypoperfused myocardium before and after thrombolysis could provide rapid and unequivocal results using fewer patients and avoiding the use of "mortality" as an end point. This approach has not yet been widely tested in the clinical arena.

Heart↗
PubMed1990

Detection and assessment of unstable angina using myocardial perfusion imaging: comparison between technetium-99m sestamibi SPECT and 12-lead electrocardiogram.

Forty-five studies using technetium-99m (Tc-99m) sestamibi single photon emission computed tomography (SPECT) were performed on patients hospitalized for spontaneous chest pain suggestive of myocardial ischemia. The studies were done after an injection during an episode of chest pain and a repeated injection when the patients were free of pain. All patients were hospitalized with a presumed diagnosis of unstable angina, and none had evidence of a previous myocardial infarction. The presence of a perfusion defect observed with Tc-99m sestamibi injected during chest pain had a 96% sensitivity and a 79% specificity for the detection of significant coronary artery disease (stenosis greater than or equal to 50%) on subsequent angiography. When the criterion of a larger perfusion defect during pain compared to absence of pain was used, the sensitivity was 81% and the specificity was 84%. In contrast, transient electrocardiographic ischemic changes during pain had a sensitivity of 35% and a specificity of 68%; electrocardiographic changes during or outside episodes of chest pain had a sensitivity of 65% and a specificity of 63% for the diagnosis. Tc-99m sestamibi SPECT represents a reliable noninvasive diagnostic tool that could aid in the diagnosis of myocardial ischemia in patients with spontaneous chest pain and provide additional information to that provided by the electrocardiogram.

Angina, Unstable↗
PubMed1990

Planar imaging techniques used with technetium-99m sestamibi to evaluate chronic myocardial ischemia.

The results of published and some unpublished studies comparing planar imaging performed with 2 radionuclides, thallium-201 (T1-201) and technetium-99m (Tc-99m) sestamibi, are reviewed. The average sensitivity for the detection of coronary artery disease (CAD) in studies involving 594 patients was 85% (range 73 to 96%). The average sensitivity for individual vessels was 65% (range 60 to 70%). The average segmental concordance between T1-201 and Tc-99m sestamibi was 89%. End-diastolic gated perfusion images improved the concordance between Tc-99m sestamibi and angiography in 22 patients from 83.4 to 87%. Semiquantitative analysis increased the concordance between T1-201 and Tc-99m sestamibi from 89 to 91%. Ventricular function derived from gated Tc-99m sestamibi perfusion images showed a significant correlation with echocardiography (n = 62, r = 0.85); with angiography (n = 70, r = 0.91); and with equilibrium radionuclide ventriculography (n = 18, r = 0.86). The ratio of lung to left ventricle uptake and the ratio of right ventricle to left ventricle uptake was assessed. Eight of 52 patients had an abnormally elevated lung index (greater than 42%) and these patients had the most severe CAD. Six of the 52 patients had an abnormally elevated right ventricular index (greater than 56%) and these patients had more severe CAD.

Coronary Disease↗
PubMed1990

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease.

Technetium-99m (Tc-99m) sestamibi is a new myocardial perfusion imaging agent that offers significant advantages over thallium-201 (Tl-201) for myocardial perfusion imaging. The results of the current clinical trials using acquisition and processing parameters similar to those for Tl-201 and a separate (2-day) injection protocol suggest that Tc-99m sestamibi and Tl-201 single photon emission computed tomography (SPECT) provide similar information with respect to detection of myocardial perfusion defects, assessment of the pattern of defect reversibility, overall detection of coronary artery disease (CAD) and detection of disease in individual coronary arteries. Tc-99m sestamibi SPECT appears to be superior to Tc-99m sestamibi planar imaging because the former provides a higher defect contrast and is more accurate for detection of disease in individual coronary arteries. Research is currently under way addressing optimization of acquisition and processing of Tc-99m sestamibi studies and development of quantitative algorithms for detection and localization of CAD and sizing of transmural and nontransmural myocardial perfusion defects. It is expected that with the implementation of the final results of these new developments, further significant improvement in image quality will be attained, which in turn will further increase the confidence in image interpretation. Development of algorithms for analysis of end-diastolic myocardial images may allow better evaluation of small and nontransmural myocardial defects. Furthermore, gated studies may provide valuable information with respect to regional myocardial wall motion and wall thickening. With the implementation of algorithms for attenuation and scatter correction, the overall specificity of Tc-99m sestamibi SPECT should improve significantly because of a substantial decrease in the occurrence of attenuation-related image artifacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗