Myocardial sestamibi single-photon emission tomography: Variations in reference values with gender, age and rest versus stress?

Reference data files support the evaluation of myocardial perfusion single-photon emission tomography (SPET). The aim of this study was to create a large reference data base for technetium-99m sestamibi SPET, age and gender matched to the general patient population. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a likelihood of coronary artery disease of less than 5% underwent rest and maximal exercise^99mTc-sestamibi SPET with a 2-day protocol and 180° elliptical rotation. The normalized activity values of^99mTc-sestamibi in the inferior wall differed significantly between men and women. Age variations were found for men in the anterior wall. Normalized activity values in all four walls were strikingly similar during rest and stress. Our results suggest that the use of reference files in^99mTc-sestamibi SPET requires a gender- and, for males, possibly an age-matched reference population. Different reference files at rest and during stress might not be necessary.     

False-positive defects in technetium-99m sestamibi myocardial single-photon emission tomography in healthy athletes with left ventricular hypertrophy

Exercise ECG and myocardial single-photon emission tomography (SPET) are fundamental in the non-invasive evaluation of patients suspected of having coronary artery disease (CAD). The purpose of the present study was to investigate the influence of physiological left ventricular hypertrophy (LVH) on myocardial sestamibi SPET in healthy young and old athletes. Eighteen young male elite athletes (ten rowers, five power/weight lifters and three triathletes) and 14 well-trained elderly rowers were studied. All underwent a bicycle test as part of a 2-day sestamibi SPET protocol. Attenuation correction was not performed. The studies were evaluated visually and quantitatively analysed by the CEqual program with its reference files and with a file from a local non-athletic age-matched population. Echocardiographic LVH was an inclusion criterion in the young athletes. Exercise ECG was normal in all subjects. In at least three of the young athletes a reversible defect was observed by visual analysis. On quantitative analysis one-third of the young athletes had ”significant” (>10 pixels) defects compared with both the local reference base and the CEqual reference population. Nearly all defects were found in the anterior or inferior wall. The remaining subjects, including all old rowers, had normal SPET findings. Anterior and inferior wall defects are so common in healthy athletes with physiological LVH that the specificity of myocardial SPET, in contrast to exercise ECG, seems to be too low for evaluation of chest pain in this group. The mechanism of anterior and inferior defects may be related to hot spots (papillary muscles?) in the lateral wall. The specificity of SPET is maintained in athletes without LVH. Received 9 March and in revised form 30 May 1998     

Technetium-99m sestamibi single-photon emission tomography detects subclinical myocardial perfusion abnormalities in patients with systemic lupus erythematosus

In patients with systemic lupus erythematosus, involvement of the cardiovascular system is the third leading cause of death. However, although autopsy studies have demonstrated a high incidence of abnormalities in both the myocardium and coronary vessels, clinical manifestations have been reported in only a small percentage of cases. The aim of this study was to evaluate myocardial perfusion in asymptomatic lupus patients using technetium-99m sestamibi single-photon emission tomography (SPET). Twenty-eight patients without overt cardiac involvement and risk factors were studied with ^99mTc-sestamibi SPET at rest and after dipyridamole infusion. Perfusion abnormalities were detected in 18 cases: six had persistent defects, three had reversible defects, seven had both persistent and reversible defects, and two showed rest defects which normalized on dipyridamole images (”reverse redistribution pattern”). Coronary angiography was performed in eight patients with positive ^99mTc-sestamibi SPET, and showed normal epicardial vessels in all the cases. These results indicate that ^99mTc-sestamibi SPET reveals a high prevalence (18 out of 28 patients in this study, i.e. 64%) of myocardial perfusion abnormalities in asymptomatic lupus patients, probably due to the primary immunological damage of this autoimmune disease. In conclusion, rest/dipyridamole ^99mTc-sestamibi SPET can be a useful non-invasive method to identify subclinical myocardial involvement in systemic lupus erythematosus, and patients potentially at risk of later cardiac events. Received 20 November 1998 and in revised form 19 February 1999     

Exercise gated planar myocardial perfusion imaging using technetium-99m sestamibi for the diagnosis of coronary artery disease: an alternative to exercise tomographic imaging

Single-photon emission tomography (SPET) using technetium-99m labelled myocardial tracers (e.g.^99mTc-sestamibi) has become one of the most popular myocardial imaging methods for the diagnosis of coronary artery disease (CAD). This prospective study was designed to evaluate the diagnostic performance of^99mTc-sestamibi exercise gated planar myocardial imaging by comparison with both visual and quantitative analyses of SPET. The study was conducted in 115 consecutive patients with known or suspected CAD, including 54 patients with a previous myocardial infarction (MI), referred for exercise testing prior to coronary angiography. Multi-gated planar imaging and SPET were performed after bicycle exercise. The end-diastolic (ED) and SPET images were visually scored (SVi). Myocardial uptake was quantitated on SPET slices using maximum count circumferential profiles (SQu) and defect extent was measured by comparison with gender-matched data sets obtained from 27 controls (<5% likelihood of CAD). CAD was defined as coronary artery stenosis >50% and/or regional wall motion abnormality. The cut-off criteria for positivity of the three procedures were determined from receiver operating characteristic (ROC) curves derived from the data of patients without previous MI. The area under the ROC curves was similar for ED, SVi and SQu. This was confirmed by the analysis of sensitivity performed using the ROC curve-derived cut-off criteria, in patients with or without previous MI. SVi was more sensitive than ED in identifying the diseased vessel(s) (ED: 41% vs SVi: 80%;P<0.0005) but ED was more specific in this respect (ED: 79% vs SVi: 61%;P<0.0005). We conclude that visual analysis of ED images obtained from gated^99mTc-sestamibi stress planar imaging is a valuable alternative to SPET imaging for the diagnosis of CAD. SPET is, however, more accurate for the evaluation of the disease extent and localization and therefore remains the method of choice for the assessment of myocardial perfusion.     

Amplitude analysis of stress technetium-99m methoxy isobutylisonitrile images in coronary artery disease

To determine the role of rest and stress gated technetium-99m methoxyisobutylisonitrile (sestamibi), in the detection of coronary artery disease, routine Fourier analysis of these images was performed with the best septal left anterior oblique (LAO) position of 20 patients (17 men, 3 women; aged 40–75 years) who also underwent rest or redistribution/stress single photon emission tomography (SPET) (^99mTc-sestamibi and Thallium-201), gated blood pool imaging and coronary angiogram. There were 6 patients with single-vessel disease, 6 with two-vessel disease, 4 with three-vessel disease, 2 with coronary spasms, 1 with a patent graft and 1 with anginal episodes but a normal angiogram result. Three normal volunteers (2 women, 1 man; aged 24–26 years) also had rest and stress gated blood pool as well as rest and stress gated ^99mTc-sestamibi imaging. Rest and stress ^99mTc-ses-tamibi amplitude and phase images depicted regional myocardial wall shortening from the outer layer of the myocardium to the center of the left ventricle as follows a high amplitude halo of maximal negative count rate variaton; a circular thinner halo of negligible amplitude; a central region of maximal positive count rate variation, as the images evolved from end-diastole to end-systole. Similar patterns with regional differences represented abnormal myocardial wall shortening. (^99mTc-sestamibi and ²⁰¹T1 SPET) images were in agreement in 90% of the patients and 92% of myocardial regions. ²⁰¹T1 SPET detected 83% of angiographically proven lesions, as compared with 80% for ^99mTc-setamibi SPET and 80% for the amplitude images. The amplitude images demonstrated a larger number of other abnormalities not predicted on the angiogram, probably because they were able to detect regions with a potential for flow improvement and transient regional wall shortening abnormalities. Amplitude and phase analyses of gated rest and stress ^99mTc-ses-tamibi images are easy to perform and may become an important adjunct to (^99mTc-sestamibi SPET) images for a complete evaluation of both regional myocardial perfusion and regional contractile function using a single tracer. Offprint requests to: E.E. Camargo     

Comparison of technetium-99m sestamibi left ventricular wall motion and perfusion studies with thallium-201 perfusion imaging: in search of the combination of variables with the highest accuracy in predicting coronary artery disease

Measurements of myocardial perfusion and ventricular function are expected to provide additional information in the detection of coronary artery disease (CAD). The purpose of this study was threefold: (1) to determine to what extent technetium-99m sestamibi wall motion yields different information compared with^99mTc-sestamibi and thallium-201 perfusion; (2) to test which information unique to either study is of value in diagnosing CAD; and (3) to assess the combination of variables with the highest diagnostic accuracy. Perfusion and wall motion scores (at rest and during exercise) obtained from visual and quantitative planar²⁰¹T1 and^99mTc-sestamibi scintigraphy of 60 patients with suspected CAD were compared with the angiographic results by means of a polytomous logistic regression model and the diagnostic values were compared with one another. All univariate variables were significantly related to the probability of CAD and its extent. Comparative studies revealed a large degree of correlation between²⁰¹T1 stress and redistribution variables. The rest^99mTc-sestamibi and wall motion studies contained partially different information. Stepwise logistic regression analysis showed the strongest diagnostic power for the combination of²⁰¹Tl visual analysis of the stress images with quantitative redistribution images (sensitivity 93%, specificity 71%). The diagnostic power was similar for all combinations of visual and quantitative analyses of the exercise and redistribution images. The strongest diagnostic power of the^99mTc-sestamibi variables was the score of the diastolic stress image (sensitivity 91%, specificity 79%). Comparable sensitivity and specificity estimates were found when both optimal models were compared. Wall motion studies did not have additional diagnostic power. Although^99mTc-sestamibi wall motion studies, both at rest and during exercise, provide information in addition to the^99mTc-sestamibi or²⁰¹Tl myocardial perfusion variables, the information does not enhance the diagnostic power with regard to the prediction of CAD.     

Comparison of 99mTc-sestamibi lung/heart ratio, transient ischaemic dilation and perfusion defect size for the identification of severe and extensive coronary artery disease

The ability to identify patients with severe coronary artery disease (CAD) by analysis of perfusion defects is limited. The lung/heart ratio (LHR) and transient ischaemic dilatation (TID) have been used for this purpose in thallium-201 scintigraphy. The value of these parameters in technetium-99m sestamibi single-photon emission tomography (SPET) imaging is controversial. In this study, therefore, we determined TID and LHR in a single-day rest/stress 99mTc-sestamibi SPET perfusion protocol and compared these measurements with perfusion defect size (PDS) and angiographic severity of CAD. Severe CAD was defined as >75% left main coronary stenosis and/or >90% proximal left anterior descending artery stenosis and/or >90% proximal stenosis in the left circumflex and right coronary arteries. LHR was determined from a stress anterior planar image recorded < or =6 min after exercise. TID ratio was derived from automatically calculated left ventricular rest/stress volumes, and PDS was measured based on semi-automated computer software (CEqual). Diagnostic accuracy and predictive values were compared between 22 patients with severe and 98 patients without severe CAD. LHRs showed a higher sensitivity (73%) for the assessment of severe CAD as compared to PDS and TID ratio (41% and 23% respectively, P<0.01), whereas specificity was highest for TID ratio [95%, P<0.01 when compared to PDS (84%) and LHR (82%)]. It is concluded that increased LHR in 99mTc-sestamibi myocardial perfusion imaging seems to yield good diagnostic accuracy in the detection of patients with severe CAD and may be derived from a single-day rest/stress study.     

Fluorine-18 deoxyglucose PET for assessment of viable myocardium in perfusion defects in 99mTc-MIBI SPET: a comparative study in patients with coronary artery disease

Extent and frequency of viable tissue in myocardial segments yielding a perfusion defect on technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI), single photon emission tomography (SPET) at rest was prospectively investigated with 2-¹⁸F-2-deoxyglucose (¹⁸FDG) positron emission tomography (PET) in 46 patients with chronic coronary artery disease (CAD). Of these, 43 had a history of old myocardial infarction. For comparative visual and quantitative evaluation of identical anatomical slices, PET image files were converted into the SPET file structure and into the same matrix size. SPET and PET images were documented and visually (9 segments/patient) or semiquantitatively evaluated by a target-like polar map. Relative perfusion was expressed in percentage of peak ^99mTc-MIBI uptake. Sample ¹⁸FDG uptake was related to the ¹⁸FDG uptake in the area of such maximal perfusion (¹⁸FDG uptake was 100% at the 100% ^99mTc-MIBI uptake area). Of 414 segments, 167 (40%) revealed a resting perfusion defect. ¹⁸FDG uptake was present in 38 (23%) of the defects, while another 40 (24%) segments yielded ¹⁸FDG uptake in the periphery of the defect. When grouped according to the degree of ^99mTc-MIBI uptake-reduction (in percentage of peak activity), 80% of severe defects (30% of peak uptake), 48% of moderate (31%–50% of peak uptake) and 31% of mild (>50% of peak uptake) defects were considered as non-viable on the basis of ¹⁸FDG uptake. Complete viability was found in none of the severe defects in contrast to 29% of moderate and 35% of mild perfusion defects. From these data we conclude that ^99mTc-MIBI uptake as a myocardial perfusion marker underestimates myocardial viability in patients with chronic CAD and after myocardial infarction. Nevertheless, only moderate reductions of ^99mTc-MIBI uptake seem to imply a greater likelihood for viability. Comparative analysis of metabolism and flow is possible with different tomographic systems and is valuable for clinical evaluation of the cardiac patient. Offprint requests to: C. AltehoeferThis paper presents in part results of the doctoral thesis of C. Feinendegen and was supported in part by the EEC Concerted Action on PET in Cardiology.It is dedicated to Prof. L.E. Feinendegen, Jülich/Düsseldorf on the occasion of his 65th birthday.     

Fluorine-18 deoxyglucose PET for assessment of viable myocardium in perfusion defects in 99mTc-MIBI SPET: a comparative study in patients with coronary artery disease.

Extent and frequency of viable tissue in myocardial segments yielding a perfusion defect on technetium-99m methoxyisobutylisonitrile (99mTc-MIBI), single photon emission tomography (SPET) at rest was prospectively investigated with 2-18F-2-deoxyglucose (18FDG) positron emission tomography (PET) in 46 patients with chronic coronary artery disease (CAD). Of these, 43 had a history of old myocardial infarction. For comparative visual and quantitative evaluation of identical anatomical slices, PET image files were converted into the SPET file structure and into the same matrix size. SPET and PET images were documented and visually (9 segments/patient) or semiquantitatively evaluated by a target-like polar map. Relative perfusion was expressed in percentage of peak 99mTc-MIBI uptake. Sample 18FDG uptake was related to the 18FDG uptake in the area of such maximal perfusion (18FDG uptake was 100% at the 100% 99mTc-MIBI uptake area). Of 414 segments, 167 (40%) revealed a resting perfusion defect. 18FDG uptake was present in 38 (23%) of the defects, while another 40 (24%) segments yielded 18FDG uptake in the periphery of the defect. When grouped according to the degree of 99mTc-MIBI uptake-reduction (in percentage of peak activity), 80% of severe defects (less than or equal to 30% of peak uptake), 48% of moderate (31%-50% of peak uptake) and 31% of mild (greater than 50% of peak uptake) defects were considered as non-viable on the basis of 18FDG uptake. Complete viability was found in none of the severe defects in contrast to 29% of moderate and 35% of mild perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic implications of combined prone and supine acquisitions in patients with equivocal or abnormal supine myocardial perfusion SPECT.

Although acquisition of (99m)Tc-sestamibi myocardial perfusion SPECT (MPS) with the patient in the prone position is commonly used to minimize attenuation artifacts, the impact of combined prone and supine imaging on the prognostic evaluation of coronary artery disease (CAD) has not been determined. The prognostic implications of MPS obtained in both prone and supine positions in patients with perfusion defects on supine MPS were evaluated. METHODS: We studied 3,834 patients who were monitored for 24.2 +/- 6.0 mo after rest (201)Tl/stress (99m)Tc-sestamibi MPS acquired during 1994-1995, when prone acquisition was performed only in patients with inferior wall perfusion defects that might represent attenuation or motion artifact. RESULTS: During follow-up, there were 132 hard events (cardiac death or myocardial infarction) and 375 total events (hard events or late myocardial revascularization). Overall, patients who underwent prone and supine acquisitions had similar characteristics to those who underwent supine-only imaging, with the exception of being more commonly male. In multivariable analysis, there were similar independent predictors for hard events and total events; the type of acquisition (prone and supine or supine-only) was not a significant predictor of either of these outcome events. After risk adjustment, the predicted event rates were nearly identical for patients undergoing prone and supine compared with supine-only studies. Both observed and predicted hard event rates of patients with normal prone and supine versus supine-only imaging were very low (observed, 0.7%/y and 0.5%/y, respectively; predicted, 1.5% over 24 mo for both). There was no reduction in the higher rates of events associated with abnormal scan results with the combination of prone and supine imaging. CONCLUSION: Patients with inferior wall defects on supine MPS that are not present on prone MPS have a low risk of subsequent cardiac events, similar to that of patients with normal supine-only studies.     

15-Year outcome after normal exercise 99mTc-sestamibi myocardial perfusion imaging: What is the duration of low risk after a normal scan?

Objective

The goal of this study was to evaluate the very long-term outcome after normal exercise ^99mTc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT). Exercise ^99mTc-sestamibi SPECT is widely used for risk stratification, but data on very long-term outcome after a normal test are scarce.

Methods

A consecutive group of 233 patients (122 men, mean age 54?±?12?years) with known or suspected coronary artery disease (CAD) underwent exercise ^99mTc-sestamibi SPECT and had normal myocardial perfusion at exercise and at rest. Follow-up endpoints were all-cause mortality, cardiac mortality, nonfatal myocardial infarction, and coronary revascularization. Predictors of outcome were identified by Cox proportional hazard regression models using clinical and exercise testing variables.

Results

During a mean follow-up of 15.5?±?4.9?years, 41 (18%) patients died, of which 13 were cardiac deaths. A total of 18 (8%) patients had a nonfatal myocardial infarction, and 47 (20%) had coronary revascularization. The annualized event rates for all-cause mortality, cardiac mortality, cardiac mortality/nonfatal infarction, and major adverse cardiac events were, respectively, 1.1%, 0.3%, 0.7%, and 1.8%. Multivariate analysis demonstrated that the variables age, male gender, diabetes, diastolic blood pressure at rest, rate pressure product at rest, peak exercise heart rate, and ST segment changes were independent predictors of major adverse cardiac events.

Conclusion

Patients with suspected or known CAD and normal exercise ^99mTc-sestamibi myocardial perfusion SPECT have a favorable 15-year prognosis. Follow-up should be closer in patients with known CAD, and/or having clinical and exercise parameters indicating higher risk status.     

Estimation of myocardial blood flow and myocardial flow reserve by <Superscript>99m</Superscript>Tc-sestamibi imaging: comparison with the results of [<Superscript>15</Superscript>O]H<Subscript>2</Subscript>O PET

We developed a noninvasive method to quantitatively estimate the myocardial blood flow (MBF) index and flow reserve (MFR) using dynamic and static data obtained with technetium-99m sestamibi, and compared the results with MBF and MFR measured by oxygen-15-labeled water ([(15)O]H(2)O) PET. Twenty patients with coronary artery disease (CAD) and nine normal subjects underwent both (99m)Tc-sestamibi and PET studies within 2 weeks. From the anterior view, dynamic data were acquired for 2 min immediately after the injection of (99m)Tc-sestamibi, and planar static images were also obtained after 5 min at rest and during ATP stress (0.16 mg kg(-1) min(-1) for 5 min) on another day. The area under the time-activity curve on the aortic arch (Aorta ACU), myocardial weight with the SPET image (M), and the myocardial count on the planar image for 1 min (C(m)) were obtained. The MBF index (MBFI) was calculated as follows: MBFI=Cm/Aorta ACU x 100M. MFR was measured by dividing the MBFI at ATP stress by MBFI at rest. The MBFI measured by (99m)Tc-sestamibi was significantly correlated with MBF obtained using [(15)O]H(2)O PET (MBFI=13.174+11.732 x MBF, r=0.821, P<0.001). Furthermore, MFR measured by (99m)Tc-sestamibi was well correlated with that obtained using [(15)O]H(2)O PET, with some underestimation (r=0.845, P<0.001). MFR using (99m)Tc-sestamibi in patients with CAD was significantly lower than that in normal subjects (CAD: 1.484+/-0.256 vs normal: 2.127+/-0.308, P<0.001). These data suggest that the MBFI and MFR can be measured with (99m)Tc-sestamibi. This may be useful for the quantitative assessment of CAD, especially in those patients with diffuse coronary disease.     

Diagnostic efficacy of stress technetium 99m-labeled sestamibi myocardial perfusion single-photon emission computed tomography in detection of coronary artery disease among patients over age 80

Background

Because symptoms of myocardial ischemia in elderly patients are often atypical, accurate noninvasive assessment of the presence, extent, and severity of coronary artery disease (CAD) would be especially useful to avoid unnecessary catheterization or invasive intervention. This study assessed the safety and diagnostic efficacy of ^99mTc-labeled sestamibi (^99mTcsestamibi) exercise and pharmacologic myocardial perfusion single-photon emission computed tomography (SPECT) with adenosine or dipyridamole in patients age 80 years or older.

Methods and Results

Stress ^99mTc-sestamibi SPECT was performed in 75 consecutive patients who were 80 years old or older (range: 80 to 91 years) with suspected CAD and who underwent coronary angiography within 6 months of the nuclear study. Of these patients, 51 underwent a pharmacologic (adenosine=42; dipyridamole=9) stress study and 24 underwent an exercise treadmill study. A normalcy rate was derived from an additional 36 patients (ages 83±3 years) who had undergone stress ^99mTc-sestamibi SPECT and who had a relatively low likelihood (<20%) of CAD. No serious adverse events occurred during or after the exercise or the pharmacologic stress test. The overall sensitivity and specificity for detecting CAD with ≥70% stenosis was 95% (52/55) and 75% (15/20), whereas the corresponding results were 87% (55/63) and 83% (10/12) for detecting patients with ≥50% stenosis. The sensitivity and specificity for pharmacologic stress ^99mTc-sestamibi SPECT were 95% (35/37) and 71% (10/14) for detecting ≥70% stenosis, and 86% (37/43) and 75% (6/8) for detecting CAD with ≥50% stenosis. The sensitivity and specificity of treadmill testing were 94% (17/18) and 83% (5/6) in detecting CAD with stenosis ≥70% and 90% (18/20) and 100% (4/4) in detecting CAD with stenosis ≥50%. The normalcy rate among the low likelihood patients was 83% (30/36). The accuracy of stress sestamibi testing was similar for patients with or without angina.

Conclusions

Our findings suggest that exercise or pharmacologic myocardial perfusion SPECT with ^99mTc-sestamibi is safe and diagnostically accurate for CAD detection in very elderly patients, irrespective of symptoms. Pharmacologic myocardial perfusion SPECT with adenosine or dipyridamole appears to be a valuable alternative to treadmill stress in very elderly patients incapable of performing adequate exercise.     

Dipyridamole and exercise SPET provide different estimates of myocardial ischaemic areas: role of the severity of coronary stenoses and of the increase in heart rate during exercise

In patients unable to perform a maximal exercise test, dipyridamole single-photon emission tomography (SPET) has a higher capacity than exercise SPET to detect coronary artery disease (CAD). However, in patients with myocardial ischaemia who are able to perform a maximal exercise test, it is not known whether these two tests may be equally used to assess the areas of myocardial ischaemia. This study was aimed at comparing the results provided by dipyridamole and exercise SPET in CAD patients with documented exercise myocardial ischaemia. Forty CAD patients who had undergone exercise thallium-201 SPET and who had myocardial ischaemia documented by an unequivocally positive exercise test underwent an additional ²⁰¹Tl SPET study after dipyridamole infusion and low-level (40 W) exercise. The extent of defects was compared between the two tests and predictors of discrepant results were sought among data from exercise testing and coronary angiography. The extent of SPET defects was equivalent between the two tests in only 11 patients (28%), larger defects being observed with exercise in 18 [average difference: 12%±5% of left ventricle (LV)] and with dipyridamole in 11 (average difference: 15%±11% of LV). The best independent predictors of discrepancies between the two tests were: (1) increase in heart rate at exercise SPET, with defects being smaller at exercise than after dipyridamole in none of the patients with an increase >60 bpm (0/14), but in 42% of the others (11/26; P=0.004); and (2) an ischaemic territory related to a <70% coronary stenosis, for which SPET defects were always induced at exercise (10/10) but in only 30% (3/10) with dipyridamole (P=0.0004). Exercise and dipyridamole SPET provide different estimates of myocardial ischaemic areas. Dipyridamole allows the unmasking of perfusion abnormalities in patients who have low increases in heart rate at exercise SPET. However, dipyridamole is also much less efficient at inducing perfusion abnormalities in the ischaemic areas supplied by coronary stenoses of intermediate severity at rest angiography. Received 20 January 2000 and in revised form 18 March 2000     

Kinetic characterization of a novel cationic <Superscript>99m</Superscript>Tc(I)-tricarbonyl complex, <Superscript>99m</Superscript>Tc-15C5-PNP,for myocardial perfusion imaging

Background  

Intense liver uptake of ^99mTc-sestamibi (MIBI) often interferes with visualization of myocardial perfusion in the inferior wall of the left ventricle. To develop improved myocardial perfusion agents, crown ether-containing dithiocarbamates and bisphosphines have been introduced in recent years. This study was designed to investigate the myocardial imaging properties and in vivo kinetics of a cationic ^99mTc(I)-tricarbonyl complex, ^99mTc-15C5-PNP, in comparison with MIBI.     

Implementation of myocardial perfusion imaging in the early triage of patients with suspected acute coronary syndromes

The risk of overlooking an underlying acute coronary syndrome remains an important challenge in patients complaining of chest pain but who have a non-diagnostic ECG (CP). Indeed, myocardial scintigraphy associated with exercise testing (exercise SPET) represents a valuable tool for excluding coronary artery disease (CAD) especially in patients with CP and delayed presentation to the emergency department. We sought to implement diagnoses of CAD in the early triage of CP patients by exercise gated SPET and compare diagnoses with outcomes. A total of 306 consecutive patients presenting with CP were found to be free of CAD at first line work-up including clinical evaluation, markers of myocardial injury and echocardiogram. These patients were studied initially with exercise SPET, and those with perfusion defects underwent angiography, while those with normal scans were discharged and followed up. Patients with positive scans (34%, n=105) had documented coronary stenoses in 43% (n=45); patients with negative scans (66%, n=201) had evidence of non-fatal coronary events at 6 months in 1.5% (n=3). When imaging was analysed with gating by the presence of transmural perfusion defects associated with wall motion abnormalities (n=86), only one patient, among 19 excluded, was recognized as having coronary stenosis by angiography (SPET vs gated SPET: negative predictive value 98.5% and 98%, respectively, P=NS; diagnostic accuracy 79% and 85%, respectively; P< or =0.03). Therefore, implementation of myocardial perfusion imaging in the early triage of patients with suspected acute coronary syndromes was effectively obtained by early exercise gated SPET, especially in patients with transmural myocardial perfusion defects associated with wall motion abnormalities.     

Technetium-99m sestamibi scintigraphy for the assessment of lower extremity ischaemia in peripheral arterial disease

Technetium-99m sestamibi was used for functional investigation of the muscle perfusion of lower extremities in 35 patients with peripheral vascular disease. The aim was to test what useful information could be obtained by additional imaging of the legs in patients referred for risk stratification with dipyridamole myocardial scanning. Posterior images were acquired over the thighs and calves after postocclusive reactive hyperaemia and at rest. Inter- and intraextremity ratios and differences between the stress and rest data were used for the assessment of abnormal circulation. Arteriography was performed in every case, and surgical procedures or transluminal angioplasty in 31 patients. To estimate diagnostic accuracy, the results of^99mTc-sestamibi scintigraphy were compared with those of angiography and the functional consequences of revascularization procedures. The sensitivity and specificity of^99mTc-sestamibi scintigraphy were 55% and 25%, respectively, with an overall accuracy of 50%. Apparently methodological error was not responsible for these poor results. Instead, a paradoxically high uptake of the radiopharmaceutical in muscles supplied by significantly stenosed vessels was identified as the main source of both false-negative and false-positive results. This phenomenon resembles the findings of a previous study involving delayed administration of thallium-201 after exercise. In conclusion,^99mTc-sestamibi scintigraphy has not proved sufficiently reliable to help in the management strategy for patients with peripheral vascular disease.     

Reversible ischemia in severe stress technetium 99m-labeled sestamibi perfusion defects assessed from gated single-photon emission computed tomographic polar map fourier analysis

Background  

Detection of reversible ischemia and regional viability by inference from the presence of preserved resting myocardial thickening on dynamic electrocardiographic-gated tomographic (GSPECT) images obtained after stress injection could potentially obviate the need for a separate resting injection. This would decrease the cost, effort, duration, and radiation exposure of diagnostic myocardial perfusion imaging. The aim of this study was to determine whether functional images derived from GSPECT stress myocardial perfusion images, which represent indices of regional wall thickening, could predict the pattern of reversibility of perfusion defects in myocardial segments with severe perfusion defects on stress ^99mTc-labeled sestamibi (^99mTc-sestamibi) images.     

Technetium-99m sestamibi single-photon emission tomography detects subclinical myocardial perfusion abnormalities in patients with systemic lupus erythematosus.

In patients with systemic lupus erythematosus, involvement of the cardiovascular system is the third leading cause of death. However, although autopsy studies have demonstrated a high incidence of abnormalities in both the myocardium and coronary vessels, clinical manifestations have been reported in only a small percentage of cases. The aim of this study was to evaluate myocardial perfusion in asymptomatic lupus patients using technetium-99m sestamibi single-photon emission tomography (SPET). Twenty-eight patients without overt cardiac involvement and risk factors were studied with 99mTc-sestamibi SPET at rest and after dipyridamole infusion. Perfusion abnormalities were detected in 18 cases: six had persistent defects, three had reversible defects, seven had both persistent and reversible defects, and two showed rest defects which normalized on dipyridamole images ("reverse redistribution pattern"). Coronary angiography was performed in eight patients with positive 99mTc-sestamibi SPET, and showed normal epicardial vessels in all the cases. These results indicate that 99mTc-sestamibi SPET reveals a high prevalence (18 out of 28 patients in this study, i.e. 64%) of myocardial perfusion abnormalities in asymptomatic lupus patients, probably due to the primary immunological damage of this autoimmune disease. In conclusion, rest/dipyridamole 99mTc-sestamibi SPET can be a useful non-invasive method to identify subclinical myocardial involvement in systemic lupus erythematosus, and patients potentially at risk of later cardiac events.     

Technetium-99m tetrofosmin rest/stress myocardial SPET with a same-day 2-hour protocol: comparison with coronary angiography A Spanish-Portuguese multicentre clinical trial

Technetium-99m tetrofosmin (Myoview) has unique properties for myocardial perfusion imaging very early after injection of the tracer. We used a very short same-day rest/stress protocol, to be performed within 2 h and evaluated its diagnostic accuracy. The study included 144 patients from seven Spanish and four Portuguese centres with a diagnosis of uncomplicated coronary artery disease (CAD); 78 patients (54%) had no history of prior myocardial infarction. Patients were injected with 300 MBq^99mTc-tetrofosmin at rest and 900 MBq approximately 1 h later at peak exercise. Single-photon emission tomographic (SPET) acquisitions were initiated within 5–30 min post injection. The results were compared with those of coronary angiography (CA). The data of 142 patients were completely evaluable (two with non-evaluable images were excluded). The quality of rest images was excellent or good in 86%, regionally problematic in 7%, poor but well interpretable in 5% and non-evaluable in 2%. The overall sensitivity for the detection of CAD was 93%, the specificity 38% and the accuracy 85%. The localization of defects by SPET in relation to the perfusion territories of stenosed vessels (50%) was achieved with a sensitivity of 64% for the left anterior descending artery, 49% for the left circumflex artery and 86% for the right coronary artery, and an accuracy of 71%, 72% and 73% respectively. Concordance of SPET and CA was 62% for single-vessel disease and 68% for multivessel disease. In conclusion, this Spanish-Portuguese multicentre clinical trial confirmed, in a considerable number of patients who underwent coronary angiography, the feasibility of^99mTc tetrofosmin (Myoview) rest/stress myocardial SPET using a very short protocol (2 h).The results contained herein were presented in part at the 2nd International Conference of Nuclear Cardiology, held in Cannes, France, on 23–26 April 1995