Transient ischemic dilation for coronary artery disease in quantitative analysis of same-day sestamibi myocardial perfusion SPECT

Background

Transient ischemic dilation (TID) of the left ventricle in myocardial perfusion SPECT (MPS) has been shown to be a clinically useful marker of severe coronary artery disease (CAD). However, TID has not been evaluated for 99mTc-sestamibi rest/stress protocols (Mibi-Mibi). We aimed to develop normal limits and evaluate diagnostic power of TID ratio for Mibi-Mibi scans.

Methods

TID ratios were automatically derived from static rest/stress MPS (TID) and gated rest/stress MPS from the end-diastolic phase (TID_ed) in 547 patients who underwent Mibi-Mibi scans [215 patients with correlating coronary angiography and 332 patients with low likelihood (LLk) of CAD]. Scans were classified as severe (??70% stenosis in proximal left anterior descending (pLAD) artery or left main (LM), or ??90% in ??2 vessels), mild to moderate (??90% stenosis in 1 vessel or ??70%-90% in ??1 vessel except pLAD or LM), and normal (<70% stenosis or LLk group). Another classification based on the angiographic Duke prognostic CAD index (DI) was also applied: DI????50, 30????DI?<?50 and DI?<?30 or LLk group.

Results

The upper normal limits were 1.19 for TID and 1.23 for TID_ed as established in 259 LLk patients. Both ratios increased with disease severity (P?<?.0001). Incidence of abnormal TID increased from 2% in normal patients to >36% in patients with severe CAD. Similarly, when DI was used to classify disease severity, the average ratios showed significant increasing trend with DI increase (P?<?.003); incidence of abnormal TID also increased with increasing DI. The incidence of abnormal TID in the group with high perfusion scores significantly increased compared to the group with low perfusion scores (stress total perfusion deficit, TPD?<?3%) (P?<?.0001). The sensitivity for detecting severe CAD improved for TID when added to mild to moderate perfusion abnormality (3%????TPD?<?10%): 71% vs 64%, P?<?.05; and trended to improve for TID_ed/TID_es: 69% vs 64%, P?=?.08, while the accuracy remained consistent if abnormal TID was considered as a marker in addition to stress TPD. Similar results were obtained when DI was used for the definition of severe CAD (sensitivity: 76% vs 66%, P?<?.05 when TID was combined with stress TPD).

Conclusion

TID ratios obtained from gated or ungated Mibi-Mibi MPS and are useful markers of severe CAD.     

The additive value of transient left ventricular dilation using two-day dipyridamole 99mTc-MIBI SPET for screening coronary artery disease in patients with otherwise normal myocardial perfusion: a comparison between diabetic and non-diabetic cases

The prognostic value of transient ischemic dilation (TID) has been previously confirmed; however, its clinical significance for screening coronary artery disease (CAD) with balanced ischemia, as a cause of false negative myocardial perfusion imaging (MPI), is unclear. The goal of this study was to determine the additive diagnostic value of TID ratio for screening CAD in separate subgroups of diabetic and non-diabetics with normal perfusion. Eighty six patients with intermediate probability of CAD who had TID more than one in the presence of otherwise normal MPI using two-day technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) single photon emission tomography (SPET) and dipyridamole stress (summed stress score<3 and left ventricular cavity<90 mL) were included in a prospective cohort study comprising two subgroups of diabetic and non- diabetic patients. An inclusive work-up with multiple noninvasive tests was performed for all patients from whom 38 cases subsequently underwent coronary angiography and 48 cases were categorized in the group with a very low likelihood (<5%) of CAD on the basis of clinical and paraclinical data over a minimum of 18 months follow up. The TID ratio was calculated using automated software. Gensini score (GS) as an indicator of severity/extent of stenosis and coronary artery index (CAI) as the number of arteries with more than 50% narrowing were calculated based on angiographic findings. Our results showed that only in diabetic patients with three-vessel disease, TID ratio (1.47 ± 0.23) differs significantly from the other groups of CAD. In diabetic patients subgroup, TID ratio correlated strongly with GS (r=0.957, P<0.0001) and CAI (r=0.659, P=0.001), while such correlations were not seen in the non-diabetic patients. On the basis of receiver operating characteristic curve analysis for screening CAD in diabetic patients with normal myocardial perfusion, 100% sensitivity and 77.8% normalcy rate were achieved when TID more than 1.16 was regarded as abnormal. No distinct cut-off value for abnormal TID was obtained in the non-diabetic patients. In conclusion, TID in diabetic patients without regional myocardial perfusion abnormality is an important sign of CAD especially when TID ratio exceeds 1.16. The higher TID ratio in these cases may predict increasing possibility of severe and extensive CAD. The value of TID in non-diabetic patients with otherwise normal MPI is not clearly determined.     

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-sestamibi 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 variation; 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 201Tl SPET images were in agreement in 90% of the patients and 92% of myocardial regions. 201Tl 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.(ABSTRACT TRUNCATED AT 250 WORDS)     

Integration of automatically measured transient ischemic dilation ratio into interpretation of adenosine stress myocardial perfusion SPECT for detection of severe and extensive CAD.

The aim of our study was to derive and to validate the normal threshold for an automatically measured left ventricular transient ischemic dilation (TID) ratio in patients referred for adenosine stress myocardial perfusion SPECT (MPS) and to assess the value of integrating TID in detecting severe and extensive coronary artery disease (CAD). METHODS: Normal limits for the TID ratio were derived using dual-isotope MPS data from 38 patients with a low (<5%) likelihood of CAD. Criteria for abnormality were calculated on the basis of data from 179 consecutive patients who had undergone coronary angiography less than 3 mo after index adenosine MPS: 41 patients (23%) had severe and extensive CAD (> or =90% stenosis) in the proximal left anterior descending artery or in 2 or more coronary arteries, 64 (36%) had no significant CAD (<70% stenosis), and 74 (41%) had mild or moderate CAD. The criteria were then prospectively validated in a cohort of 177 patients, of whom 41 patients (23%) had severe and extensive CAD, 55 (31%) had no significant CAD, and 81 (46%) had mild or moderate CAD. RESULTS: By analysis of receiver-operating-characteristic curves, the best threshold for adenosine TID ratio abnormality was the mean adenosine TID ratio in the low-CAD-likelihood patients + 2 SDs (TID ratio > 1.36). Abnormal TID ratio using this threshold demonstrated high sensitivity and specificity for severe and extensive CAD (71% and 86%, respectively), and similar sensitivity and specificity were observed in the prospective validation group (73% and 88%, respectively). In the combined pilot and validation groups, the absence of both abnormal TID ratio and abnormal perfusion was highly specific for the absence of severe and extensive CAD; only one (1.3%) of 79 patients with severe and extensive CAD had neither of these abnormal findings on adenosine MPS. In patients with both abnormal TID ratio and abnormal perfusion, 55 of 84 (65%) had severe and extensive CAD. When patients had one but not both of these findings, 26 of 193 (13%) had severe and extensive CAD. CONCLUSION: The automatically measured TID ratio is a useful clinical marker that is sensitive and highly specific for identification of severe and extensive CAD in patients undergoing adenosine MPS. Integration of abnormal TID ratio into the dual-isotope MPS image interpretation algorithm improves the identification of severe and extensive CAD in adenosine MPS.     

Comparison of methods for quantification of transient ischaemic dilation in myocardial perfusion SPET

The purpose of this study was to compare six methods of measuring the left ventricular (LV) transient ischaemic dilation (TID) ratio during stress-rest myocardial perfusion single-photon emission tomography (SPET). The TID ratio was defined as the mean LV short-axis area at stress divided by the mean LV area of similar slices at rest. The centre of the LV wall was defined as either the maximum, mean or median of the radial short-axis count profiles. The area within the endocardial wall was also calculated for each definition of the LV wall centre. We identified 50 consecutive patients undergoing dipyridamole technetium-99m-tetrofosmin SPET imaging and angiography. Continuous receiver operating characteristic (CROC) analysis showed no significant difference between the six methods in terms of identifying severe coronary artery disease (P >0.47). Algorithms using the mean or the median value in the profile were significantly more robust than those using the maximum (P <0.0005). TID measured by all the algorithms is an indicator of severe coronary disease (P < 0.05). The algorithms compared provide a repeatable, quantitative and specific measure of the TID ratio.     

Transient ischemic dilation in SPECT myocardial perfusion imaging for prediction of severe coronary artery disease in diabetic patients

Background

Transient ischemic dilation (TID) of the left ventricle during stress myocardial perfusion SPECT (MPS) has been shown to be a useful marker of severe coronary artery disease (CAD). However, investigations in diabetic patients with available coronary angiographic data are still limited. We evaluated the incremental diagnostic value of TID in identifying the presence of angiographically severe CAD in diabetic patients.

Methods and Results

TID ratio values were automatically derived from rest-stress MPS in 242 diabetic patients with available coronary angiography data. A cutoff of ≥1.19 was considered to represent TID. Severe CAD (≥70% stenosis in the proximal left anterior descending artery or the left main artery, or ≥90% stenosis in two or three vessels) was identified in 69 (29%) patients. At multivariate analysis, the best independent predictors of severe CAD were summed stress score and TID (both P < .001). At incremental analysis, the addition of TID improved the power of a model including clinical data and summed stress score, increasing the global χ² value from 14.3 to 28.2 (P < .01). The best cutoff of summed stress score for identifying patients with severe CAD was ≥8. When the TID ratio was considered in patients with summed stress score between 3 and 7, the sensitivity for diagnosing severe CAD significantly improved from 71% to 77% (P < .05). In the overall study population, the net reclassification improvement by adding TID to a model including clinical data and summed stress score in the prediction of severe CAD was 0.40 (P < .005).

Conclusions

TID ratios obtained from rest-stress MPS provide incremental diagnostic information to standard perfusion analysis for the identification of severe and extensive CAD in diabetic patients.     

Semiquantification of pulmonary and hepatic uptake of technetium-99m-tetrofosmin in myocardial perfusion imaging using multiple regions of interest. Multifactorial correlation

Various regions of interest (ROI) are used to semiquantify lung-to-heart (LHR) and liver-to-heart uptake ratios (LH) in myocardial perfusion imaging (MPI) with technetium-99m analogues. However, in bibliography, these ratios are correlated to a moderate number of clinicolaboratory indices for coronary artery disease (CAD). The aim of this study was: a) to find the best ROI positioning among one hepatic and multiple pulmonary ROI used to semiquantify technetium-99m tetrofosmin, single photon emission tomography myocardial perfusion scan (99mTc-TF SPET), LHR and LH ratios, b) to compare the diagnostic potential of the better selected ROI in correlation with: SPET scores, rest left verticular ejection fraction, five risk factors (RF) of CAD, (smoking, diabetes mellitus, hypertension, hyperlipemia and abnormal exercise-ECG) and coronary angiography (CAR), regarding the latter as the "gold standard" for the severity of CAD and c) to study the multivariate correlations among all the aforementioned diagnostic parameters, so that to rank them according their ability to screen and stratify the existence and the severity of CAD. We have studied 73 patients (54 men and 19 women, mean aged 58.5+/-10.3 and 59.8+/-8.7 years respectively), who underwent stress-rest 99mTc-TF SPET scan. All patients were classified according the following criteria: (a) CAR criteria: Group I: 34 patients with low likelihood of CAD, Group II: 19 patients with moderate CAD, Group III: 7 patients with severe CAD, Group IV: 13 patients with myocardial infarction. (b) RF criteria: Group A: 24 patients with 0-1 RF and Group B: 49 patients with >or=2 RF. (c) LVEF criteria: Group 0: 25 patients with LVEF>50, Group 1: 31 patients with LVEF=40-50, and Group 2: 4 patients with LVEF<40. (d) Regarding the existence (yes/no) of each RF (10 more subgroups). All patients underwent anterior planar imaging before the SPET scan acquisition. ROIs were placed on the following regions: Over the whole myocardium, peripherally, around the upper part of the previous ROI, on the lower right lung field, encompassing the whole right lung, on the middle mediastinum and around the upper part of the liver. Our results by multivariate regression analysis, showed that in 99mTc-TF SPET scan a modified technique of a peripheral ROI, drawn around the upper part of the heart, should be proposed as the optimal method for the calculation of LHR. This index, with normal cutoff or=2 RF. Due to the large variability of the hepatic uptake among the various groups, the diagnostic potential of LH ratio was not important.     

Quantitative relationship of stress tc-99m sestamibi lung uptake with resting tl-201 lung uptake and with indices of left ventricular dysfunction and coronary artery disease

BACKGROUND: We investigated the relationship of stress technetium 99m sestamibi lung uptake with rest thallium 201 lung uptake and with indices of left ventricular (LV) dysfunction and severity of coronary artery disease (CAD) in patients with known or suspected CAD undergoing stress testing and cardiac catheterization. Stress Tc-99m sestamibi lung uptake and both stress and rest Tl-201 lung uptake are associated with LV dysfunction and extent of CAD. Although the mechanism of lung uptake is thought to be similar for the two isotopes, their physiologic characteristics are different. No direct comparison of lung uptake for the two isotopes has been reported. METHODS AND RESULTS: We evaluated 192 consecutive patients who underwent dual-isotope myocardial perfusion imaging and cardiac catheterization within 30 days. We examined the relationship of stress Tc-99m sestamibi lung-to-heart ratio (LHR) with rest Tl-201 LHR, with indices of myocardial perfusion, and with invasive measures of the severity of LV dysfunction and CAD. Stress Tc-99m sestamibi LHR correlated with rest Tl-201 LHR (r = 0.548, P <.001). Stress Tc-99m sestamibi LHR was positively associated with LV filling pressures and extent of CAD and negatively associated with LV ejection fraction and arterial systolic blood pressure. However, after adjustment for multiple comparisons, stress Tc-99m sestamibi LHR was significantly associated only with LV end-diastolic pressure (r = 0.287, P =.002) and pulmonary capillary wedge pressure (r = 0.337, P <.001). CONCLUSIONS: Increased stress Tc-99m sestamibi LHR correlates with rest Tl-201 LHR in patients with known or suspected CAD. Stress Tc-99m sestamibi lung uptake is also associated with invasively measured LV filling pressures.     

Prospective evaluation of the impact of diabetes and left ventricular hypertrophy on the relationship between ischemia and transient ischemic dilation of the left ventricle on single-day adenosine Tc-99m myocardial perfusion imaging

Background. Diabetes and left ventricular hypertrophy (LVH) can cause coronary flow reserve abnormalities in the absence of coronary artery disease (CAD). We sought to evaluate the impact of LVH and diabetes on the relationship between ischemia, severe CAD, and transient ischemic dilation (TID) on adenosine myocardial perfusion imaging (MPI). Methods and Results. We prospectively recruited 157 patients referred for routine single-day adenosine technetium 99m MPI. LVH was assessed by use of transthoracic echocardiography. A ratio of 1.19 or greater on MPI defined TID in men and 1.31 or greater in women. Summed difference scores were determined by use of a 17-segment 5-point scoring system. TID was present in 22 of 157 patients (14%), diabetes in 54 of 157 (34%), and LVH in 42 of 157 (27%). By multivariate logistic regression, LVH, ischemia (summed difference score >2), and diabetes were independently predictive of TID. The incidence of TID was stratified by the presence or absence of diabetes and/or LVH in those with ischemia on MPI (8/8 [100%] vs 0/11 [0%], P<.002) or severe CAD on angiography (5/7 [71%] vs 0/8 [0%], P<.01). All those with TID (22/22 [100%]) had either diabetes or LVH (or both). Conclusion. Although this study confirms the association between TID and both ischemia and severe CAD, all patients with TID had diabetes, LVH, or frequently, both, suggesting that the pathophysiology of these disease processes may play an integral role in the manifestation of TID on adenosine MPI.     

A new algorithm for the quantitation of myocardial perfusion SPECT. II: validation and diagnostic yield.

This study validates a new quantitative perfusion SPECT algorithm for the assessment of myocardial perfusion. The algorithm is not based on slices and provides fully 3-dimensional sampling and analysis independent of assumptions about the geometric shape of the left ventricle. METHODS: Radiopharmaceutical- and sex-specific normal limits and thresholds for perfusion abnormality in 20 segments of the left ventricle were developed for separate, dual-isotope rest 201Tl-exercise 99mTc-sestamibi SPECT in 36 patients with <5% before-scanning likelihood of coronary artery disease (CAD) (group 1) and 159 patients with perfusion abnormalities (group 2). These thresholds were validated in 131 patients (group 3) by comparison with expert visual interpretation. Thresholds for automatic segmental scores were developed and validated for groups 2 and 3, respectively. The accuracy of CAD detection was assessed in 94 patients, who underwent coronary angiography (group 4). RESULTS: Overall sensitivity for detection of stress and rest segmental perfusion abnormality was 91% and 96%, respectively, for men and 89% and 79%, respectively, for women. Overall specificity for stress and rest was 87% and 90%, respectively, for men and 88% and 90%, respectively, for women. Agreement between automatic and visual scores was good (weighted K of 0.71 and 0.60 for stress and rest images, respectively). Sensitivity and specificity were 88% for the detection of > or =70% stenosis. For the detection of left anterior descending, left circumflex, and right coronary artery stenosis, sensitivity was 84%, 86%, and 88%, respectively, and specificity was 84%, 88%, and 81%, respectively. CONCLUSION: The new quantitative perfusion SPECT approach is highly sensitive and specific for the detection and localization of CAD, provides accurate automatic scores for the assessment of regional perfusion, and overcomes the low-specificity limitations of previous quantitative algorithms.     

Increased resting Tl-201 lung-to-heart ratio is associated with invasively determined measures of left ventricular dysfunction,extent of coronary artery disease,and resting myocardial perfusion abnormalities

BACKGROUND: Stress lung thallium 201 uptake correlates with left ventricular (LV) dysfunction and extent of coronary artery disease (CAD). Although Tl-201 is used less commonly for stress imaging, dual-isotope stress and viability protocols continue to use Tl-201 for rest imaging. We sought to investigate the association between increased resting Tl-201 lung-to-heart ratio (LHR) and hemodynamic indices of LV dysfunction, indices of myocardial perfusion, and extent of CAD. METHODS AND RESULTS: Over a 1-year period, we identified 192 consecutive patients who underwent dual-isotope stress perfusion imaging and cardiac catheterization within 30 days, without interim events or revascularization. Resting LHR was measured, and its association with invasively measured hemodynamic parameters, extent of CAD, and indices of myocardial perfusion at rest and stress was examined. Increased resting Tl-201 LHR was weakly but significantly associated with lower LV ejection fraction (EF) (r = 0.209, P <.05), higher pulmonary capillary wedge pressure (r = 0.25, P <.005), and LV end-diastolic pressure (r = 0.215, P <.01) but not with pulmonary artery systolic pressure. Increased LHR was also weakly associated with rest perfusion abnormalities including the sum rest score (r = 0.271, P <.001) and number of abnormally perfused segments (r = 0.25, P <.001) bud did not correlate with stress perfusion indices or ischemic burden. The 76 patients (40%) with LHR greater than 0.5 were more likely to have LVEF lower than 40% and 3-vessel/left main CAD. CONCLUSIONS: Increased rest Tl-201 LHR is weakly associated with higher LV end-diastolic pressure and pulmonary capillary wedge pressure and lower LVEF. LHR is also associated with the extent of previously infarcted myocardium and may indicate the presence of 3-vessel/left main CAD.     

Assessment of transient left ventricular dilation ratio via 2-day dipyridamole Tc-99m sestamibi nongated myocardial perfusion imaging

Background  The definition of an abnormal transient ischemic dilation (TID) ratio may be different according to stress type, type of isotope, and imaging protocols. The aim of this study was to derive the normal threshold and assessment of the TID ratio via 2-day dipyridamode stress/rest technetium 99m sestamibi myocardial perfusion single photon emission computed tomography (MPS). Methods and Results  We performed 2-day dipyridamole stress/rest Tc-99m sestamibi MPS in 665 patients. The TID ratio was calculated automatically with the Emory Cardiac Toolbox. The upper limit of normal (1.19) for the TID ratio was derived from 131 patients with a low (<5%) likelihood of coronary artery disease as mean +2 SDs. Patients with complete or partial reversible defects or multivessel-type or left anterior descending artery (LAD) territory perfusion abnormalities had higher TID ratios than the other patients. These patients had a higher frequency of an abnormal TID ratio (>1.19) as well. Binary logistic regression analysis showed that ischemia and LAD territory perfusion abnormality were independent predictors of an abnormal TID ratio. Conclusion  The threshold for an abnormal TID ratio via 2-day post-dipyridamole stress/rest Tc-99m sestamibi MPS was greater than 1.19. By use of this protocol, TID is not uncommon and it is related to a greater amount of ischemic burden as well as multivessel-type or LAD territory perfusion abnormality.     

Clinical correlates of Tc-99m sestamibi lung uptake

BACKGROUND: Increased lung uptake of thallium 201 during myocardial perfusion scintigraphy is related to severe coronary artery disease (CAD), but a similar relationship for technetium 99m sestamibi has not been clearly established. METHODS AND RESULTS: Resting and stress lung-heart ratios (LHR) were retrospectively determined in 96 patients who underwent Tc-99m sestamibi stress testing and coronary angiography within 4 months of each other. A semiquantitative CAD severity score (CADSS) was derived from the coronary angiogram. Left ventricular (LV) function was assessed in a subgroup of 42 subjects. CADSS of 24 or higher was associated with increased stress LHR compared with angiographically normal individuals (P =.009). Patients with severely impaired LV function also had a higher mean stress LHR than those with normal LV function (P =.01). Stress LHR was significantly greater than resting LHR in patients with coronary disease (0.32 +/- 0.07 vs 0.30 +/- 0.07; P =.003) and impaired LV function (0.35 +/- 0.08 vs 0.31 +/- 0.07; P <.02). CADSS correlated with stress, but not resting, LHR (P =.006), whereas the degree of LV dysfunction correlated with both resting (P =.046) and stress (P =.004) LHR. Left anterior descending (P =.017) and left main (P =.03) stenoses were independent predictors of increased stress LHR. CONCLUSIONS: An increase in stress Tc-99m sestamibi lung uptake is a marker for severe CAD. Correlation of stress LHR, but not resting LHR, with CAD severity supports exercise-induced pulmonary congestion as the underlying mechanism.     

Comparison of pulmonary uptake with transient cavity dilation after dipyridamole Tl-201 perfusion imaging

BACKGROUND: Elevated lung-heart ratio (LHR) and transient ischemic dilation (TID) have been identified as markers of severe coronary artery disease after both exercise and pharmacologic stress testing. We have previously demonstrated a very weak correlation between elevated LHR and TID after exercise, which suggests that they reflect different pathophysiologic manifestations of coronary disease. Because the physiology of pharmacologic vasodilation with dipyridamole is significantly different than that of physical exercise, we undertook this study to evaluate the relationship between elevated LHR and TID after pharmacologic stress testing with dipyridamole. METHODS AND RESULTS: We identified 1129 consecutive patients who underwent pharmacologic stress imaging with dipyridamole and thallium 201. LHR and a dilation index were calculated and compared with each other and with relevant clinical parameters. Echocardiographic parameters were also compared in a subset of 475 patients who had echocardiography within 2 weeks of pharmacologic stress testing. There was no significant correlation between elevated LHR and TID despite the fact that both were associated with more severe thallium stress and redistribution scores. Patients with elevated LHR were more likely to have a history of myocardial infarction and coronary artery bypass grafting and to have lower ejection fraction. Patients with TID were more likely to have a positive electrocardiographic response (15% vs 7%, P =.0003), which was not seen in patients with elevated LHR (11% vs 8%, P =.23). CONCLUSIONS: Although both elevated LHR and TID were associated with more severe coronary disease, they have no significant correlation. Patients with elevated LHR are more likely to have a history of myocardial infarction or coronary artery bypass grafting, a larger left ventricle, and lower ejection fraction. Our results support the hypothesis that TID is due to diffuse subendocardial hypoperfusion and represents a different pathophysiologic response to ischemia than elevated LHR.     

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.     

Gated single-photon emission tomography imaging protocol to evaluate myocardial stunning after exercise

This study was designed to apply ECG-gating to stress myocardial perfusion single-photon emission tomography (SPET) for the evaluation of myocardial stunning after exercise. Technetium-99m sestamibi was selected as the perfusion agent and a rest/exercise 1-day protocol was employed. Fourteen patients without coronary stenosis and 33 patients with coronary stenosis were enrolled in the study. We carried out three data acquisitions with ECG-gating: a 15-min data acquisition starting 30 min after the rest injection (AC1), a 5-min acquisition starting 5 min after the stress injection (AC2) and a 15-min acquisition starting 20 min after the stress injection (AC3). Calculation of left ventricular ejection fraction (LVEF) values was performed by means of automatic determination of the endocardial surface for all gating intervals in the cardiac cycle. Measured global EF values in 14 patients without coronary stenosis were 52.3% +/- 7.6% (AC1), 60.6% +/- 8.9% (AC2) and 55.6% +/- 5.6% (AC3), and those in 11 patients with severe ischaemia were 53.6% +/- 8.0% (AC1), 45.6% +/- 12.1% (AC2) and 49.7% +/- 10.7%. The magnitude of the depression of post-stress LVEF relative to the rest LVEF correlated with the severity of ischaemia (r = 0.594, P = 0.002), and segments manifesting post-stress functional depression were associated with ischaemic segments showing reversible perfusion defects. Stress myocardial perfusion SPET with ECG-gating is a feasible method for the evaluation of myocardial stunning as well as exercise-induced ischaemia.     

Gated single-photon emission tomography imaging protocol to evaluate myocardial stunning after exercise

This study was designed to apply ECG-gating to stress myocardial perfusion single-photon emission tomography (SPET) for the evaluation of myocardial stunning after exercise. Technetium-99m sestamibi was selected as the perfusion agent and a rest/exercise 1-day protocol was employed. Fourteen patients without coronary stenosis and 33 patients with coronary stenosis were enrolled in the study. We carried out three data acquisitions with ECG-gating: a 15-min data acquisition starting 30 min after the rest injection (AC1), a 5-min acquisition starting 5 min after the stress injection (AC2) and a 15-min acquisition starting 20 min after the stress injection (AC3). Calculation of left ventricular ejection fraction (LVEF) values was performed by means of automatic determination of the endocardial surface for all gating intervals in the cardiac cycle. Measured global EF values in 14 patients without coronary stenosis were 52.3%±7.6% (AC1), 60.6%±8.9% (AC2) and 55.6%± 5.6% (AC3), and those in 11 patients with severe ischaemia were 53.6%±8.0% (AC1), 45.6%±12.1% (AC2) and 49.7%±10.7%. The magnitude of the depression of post-stress LVEF relative to the rest LVEF correlated with the severity of ischaemia (r=0.594, P=0.002), and segments manifesting post-stress functional depression were associated with ischaemic segments showing reversible perfusion defects. Stress myocardial perfusion SPET with ECG-gating is a feasible method for the evaluation of myocardial stunning as well as exercise-induced ischaemia. Received 13 June and in revised form 19 August 1999     

Attenuation correction reveals gender-related differences in the normal values of transient ischemic dilation index in rest-exercise stress sestamibi myocardial perfusion imaging

BACKGROUND: Transient ischemic dilation (TID) has been established as an important independent marker of severe and extensive coronary artery disease (CAD) in myocardial perfusion imaging (MPI). The accuracy of the TID index is dependent on a well-determined threshold (normal limits) between normal and abnormal values for each study protocol. To date, the effects of neither gender nor attenuation correction (AC) on TID normal limits have been established. Thus, the objectives of this study were to determine if AC processing changes the normal value of the TID index and if there were gender-related differences in the TID index of normal patients who had undergone rest/exercise-stress technetium-99m sestamibi MPI. METHODS AND RESULTS: Seventy-five patients (33 women, 42 men; mean age, 57.7 +/- 11.7 y and 55.9 +/- 10.0 y, respectively) with less than a 5% likelihood of CAD, who had undergone low-dose rest/high-dose exercise-stress Tc-99m sestamibi MPI, were studied. All studies were acquired using simultaneous emission/transmission scans and were corrected for attenuation, scatter, and resolution effects using the ExSPECT II method. Both the AC and non-AC studies were analyzed using the Emory Cardiac Toolbox (ECTb; Syntermed, Inc, Atlanta, Ga) quantitative software. The TID index was calculated automatically as the ratio of stress mean left ventricular volumes to rest mean left ventricular volumes by ECTb. Patients were grouped by gender and the TID indices from AC and non-AC studies were compared. Linear regressions of the TID index and body mass index were analyzed to exclude differences in body size between male and female patients as a confounding factor in gender-related differences in TID. The TID index upper normal limits were calculated as the mean value plus 2 standard deviations (SDs). AC processing did not change the TID index significantly whether the genders were combined or separated (AC TID = 0.97 +/- 0.14 vs non-AC TID = 0.98 +/- 0.12 for all patients). Female patients showed higher mean TID indices than male patients in both AC (1.01 +/- 0.15 vs 0.95 +/- 0.12) and non-AC studies (1.00 +/- 0.15 vs. 0.97 +/- 0.10), but this difference was statistically significant only in AC studies (p = .03). TID indices remained constant across the range of body mass index studied. The TID index upper normal limit was 1.31 for female and 1.18 for male patients. CONCLUSION: TID normal values for rest/exercise-stress Tc-99m sestamibi MPI are gender-dependent and not affected by AC processing. Thus, diagnosticians should take into account these gender-related differences, as compared with the traditional value generated from mostly male populations, to ensure both men and women have the same overall accuracy of using the TID index in the diagnosis and prognosis of CAD.     

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.     

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