Reproducibility of Tl-201 and Tc-99m sestamibi gated myocardial perfusion SPECT measurement of myocardial function

BACKGROUND: We compared the reproducibility of thallium 201 and technetium 99m sestamibi (MIBI) gated single photon emission computed tomography (SPECT) measurement of myocardial function using the Germano algorithm (J Nucl Med 1995;36:2138-47). METHODS AND RESULTS: Gated SPECT acquisition was repeated in the same position in 30 patients who received Tl-201 and in 26 who received Tc-99m-MIBI. The quantification of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) on Tl-201 and Tc-99m-MIBI gated SPECT was processed independently with Cedars-Sinai QGS (Quantitative Gated SPECT) software. The reproducibility of the measurement of ventricular function on Tl-201 gated SPECT was compared with that of Tc-99m-MIBI gated SPECT. Correlation between the 2 measurements for volumes and EF was excellent for the repeated gated SPECT studies of Tl-201 (r = 0.928 to 0.986, P <.05) and Tc-99m-MIBI (r = 0.979 to 0.997, P <.05). However, Bland-Altman analysis revealed the 95% limits of agreement (2 SDs) for volumes and EF were narrower by repeated Tc-99m-MIBI gated SPECT (EDV 14.1 mL, ESV 9.4 mL, EF 5.5%) than by repeated Tl-201 gated SPECT (EDV 24.1 mL, ESV 18.6 mL, EF 10.3%). The root-mean-square values of the coefficient of variation for volumes and EF were smaller by repeated Tc-99m-MIBI gated SPECT (EDV 2.1 mL, ESV 2.7 mL, EF 2.3%) than by repeated Tl-201 gated SPECT (EDV 3.2 mL, ESV 3.5 mL, EF 5.2%). CONCLUSIONS: QGS provides an excellent correlation between repeated gated SPECT with Tl-201 and Tc-99m-MIBI. However, Tc-99m-MIBI provides more reproducible volumes and EF than Tl-201. Tc-99m-MIBI gated SPECT is the preferable method for the clinical monitoring of ventricular function.     

Comparison of Tc-99m sestamibi and Tl-201 gated perfusion SPECT

BACKGROUND: To determine the interpretability of gated thallium-201 perfusion SPECT compared with that performed by use of technetium-99m sestamibi (MIBI), 33 patients with prior myocardial infarction were studied. Patients received 22 to 30 mCi (814 to 1110 MBq) MIBI at peak stress, and a 15-minute gated SPECT acquisition was begun 30 to 40 minutes thereafter. On a subsequent day gated Tl-201 SPECT was acquired for 15 minutes, 4 hours after a resting 3.5 mCi (130 MBq) injection. SPECT was performed over a 180-degree arc by use of a 90-degree angled 2-detector camera. RESULTS: Gated studies were interpreted independently by 4 experienced physicians. Study quality was graded (0 = uninterpretable to 4 = excellent). Wall motion (0 = normal to 2 = akinetic/dyskinetic) and wall thickening (0 = normal to 2 = absent) were graded for each of 10 segments viewed in orthogonal planes. Left ventricular ejection fraction (LVEF) was calculated by use of software thus far validated only for MIBI. The average count density of mid-ventricular end-diastolic short axis tomograms with sestamibi was 3.47 times greater than with thallium. Mean study quality was 3.4 for MIBI and 1.8 for thallium (P < 10(-6)). No gated MIBI SPECTs, but 2 gated thallium studies (6%) were judged uninterpretable. Among interpretable scans, interobserver agreement (Kendall statistic) in assessing wall motion was 0.73 for MIBI and 0.66 for thallium (P = .01). For assessing wall thickening, the Kendall statistic was 0.73 for MIBI and 0.69 for thallium (P = .05). Correlation (r) of LVEFs was 0.91, SEE = 6.4. CONCLUSIONS: We conclude that gated thallium SPECT is inferior to MIBI because of much poorer image quality and somewhat poorer interobserver agreement among experienced physicians. However, LVEF can be determined reliably from gated thallium SPECT.     

Serial assessment of left ventricular function in various patient groups with Tl-201 gated myocardial perfusion SPECT

Purpose The present study was performed to assess stress-related left ventricular (LV) function variations in various patient groups and to determine if they were affected by sex or the type of stress experienced. We used thallium (Tl)-201 gated myocardial perfusion single-photon emission computed tomography (SPECT) for the analysis. Materials and methods A total of 270 patients were examined by electrocardiography-gated myocardial perfusion SPECT imaging to assess LV function. After injection of Tl-201 at a dose of 111 MBq at peak stress, SPECT scans were acquired at 10 min (after stress) and 3 h (rest) after injection on a three-headed camera. Results In the normal perfusion group, the mean LV ejection fraction (LVEF) was significantly higher, and both the end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) were significantly lower in women than in men (P < 0.05). Poststress stunning occurred in 29 of 98 patients (30.0%) in the ischemia group and in 42 of 90 patients (46.7%) in the fixed group. There was a significant difference in poststress stunning between bicycle ergometer stress and dipyridamole stress (P < 0.05). Conclusion In patients with normal perfusion, LVEF, EDVI, and ESVI determined by gated Tl-201 SPECT should be corrected for sex. In addition, the influence of the type of stress should be considered when assessing stress-related LV function variations.     

Q-wave regression after acute myocardial infarction assessed by Tl-201 myocardial perfusion SPECT

BACKGROUND: The actual relationship between the interval change of myocardial thallium 201 (Tl-201) radioactivity in the infarct area and the pattern of Q-wave regression is still unknown. This study was conducted to evaluate their relationship after acute myocardial infarction (AMI). METHODS AND RESULTS: A total of 30 patients who had a first Q-wave AMI (11 without Q-wave regression and 19 with Q-wave regression) were retrospectively included. Two sets of 12-lead surface electrocardiograms and Tl-201 myocardial perfusion images were obtained 0 to 2 months and 14 to 84 months after the AMI event, respectively. The acute/subacute redistribution Tl-201 radioactivity was similar between the patients with and those without Q-wave regression. However, the patients with Q-wave regression had higher chronic redistribution Tl-201 radioactivity than those without Q-wave regression. Moreover, the patients with Q-wave regression presented a higher gradient in the redistribution Tl-201 radioactivity between the chronic and acute/subacute images than those without Q-wave regression. CONCLUSIONS: This study supports the role of functional recovery of stunning and/or hibernating myocardium in the disappearance of Q waves after AMI.     

Accuracy of left ventricular ejection fraction determined by gated myocardial perfusion SPECT with Tl-201 and Tc-99m sestamibi: Comparison with first-pass radionuclide angiography

BACKGROUND: We compared estimates of left ventricular ejection fraction (LVEF) assessed by gated single photon emission computed tomography (SPECT), using both technetium-99m sestamibi and thallium-201, with those obtained by first-pass radionuclide angiography (FPRNA) in patients with a broad spectrum of LVEF and perfusion abnormalities. METHODS: Sixty-three patients were randomly selected to undergo a dual isotope gated SPECT study (rest Tl-201 followed by adenosine Tc-99m sestamibi scintigraphy). Studies were processed by use of the Cedars quantitative gated SPECT software. FPRNA was acquired during an intravenous bolus injection of Tc-99m sestamibi and processed with a commercially available software. RESULTS: The estimates of LVEF were similar (P = NS) with Tl-201 gated SPECT (54% +/- 15%), Tc-99m gated SPECT (54% +/- 16%), and FPRNA (54% +/- 12%). There was an excellent correlation between Tc-99m and Tl-201 gated SPECT (Pearson's r = 0.92, P < .0001). There were also good linear correlations between Tc-99m sestamibi gated SPECT and FPRNA (Pearson's r = 0.85, P < .0001), as well as between Tl-201 gated SPECT and FPRNA (Pearson's r = 0.84, P < .0001). In the 16 patients with LVEF < 50%, Tc-99m sestamibi gated SPECT and FPRNA (Pearson's r = 0.84, P < .0001) and Tl-201 gated SPECT and FPRNA (Pearson's r = 0.92, P < .0001) correlated well. CONCLUSION: LVEF can be accurately assessed by gated SPECT with either Tc-99m sestamibi or Tl-201 in properly selected patients with normal or depressed left ventricular function.     

Relationship of transient ischemic dilation in dipyridamole myocardial perfusion imaging and stress-induced changes of functional parameters evaluated by Tl-201 gated SPECT

BACKGROUND: This study assessed whether transient ischemic dilation (TID) of the left ventricle is related to ischemic stunning, manifested by stress-induced decrease of left ventricular ejection fraction (LVEF) and worsening of wall motion, by use of dipyridamole-stress and redistribution thallium 201 gated single photon emission computed tomography (SPECT). METHODS AND RESULTS: Ninety-two consecutive patients undergoing dipyridamole Tl-201 gated SPECT were included. Patients with a TID ratio in the highest quartile were defined as having TID. In patients with TID, end-diastolic volume (EDV) and end-systolic volume (ESV) were both significantly greater on dipyridamole-stress images than on redistribution images (P < .001). The degree of enlargement was much greater for ESV than EDV. In patients without TID, EDV and ESV were both decreased after stress (P < .001). Patients with TID had a lower mean LVEF on dipyridamole-stress images than on redistribution images (P < .001). Patients without TID had a higher mean LVEF on dipyridamole-stress images than on redistribution images (P < .001). Patients with TID had a significant worsening of global wall motion on dipyridamole-stress images than on redistribution images (P < .001), but patients without TID did not. CONCLUSION: TID was significantly correlated with ischemic stunning, and the enlargement of ESV was an important factor resulting in TID.     

Feasibility of detecting cardiac torsion in myocardial perfusion gated SPECT data

BACKGROUND: The dynamic twisting component of cardiac motion is not accounted for by radionuclide techniques so that maps of perfusion and wall thickening are motion-blurred by torsion. This study examined whether torsion can be estimated from gated single photon emission computed tomography data and whether torsion corrections affect cardiac measurements. METHODS AND RESULTS: Technetium 99m sestamibi myocardial perfusion gated tomograms were selected retrospectively for 52 patients who had x-ray contrast arteriograms: 12 with normal perfusion (group 1), 12 with abnormal perfusion (group 2), and 28 studied after angioplasty (group 3). The 8 gated perfusion maps were transformed by contrast normalization, the count minimums of which were tracked to quantify torsion. Measured torsion was used to correct maps of perfusion and wall thickening. Torsion was found to be visually detectable equally well in groups 1 and 2. Apical torsion was significantly greater for group 1 than groups 2 and 3 (15 degrees +/- 9 degrees vs 9 degrees +/- 15 degrees and 2 degrees +/- 12 degrees ) and was opposite in sign for patients with apical aneurysms (-4 degrees +/- 13 degrees ) and for patients after coronary artery bypass grafting (CABG) (-4 degrees +/- 15 degrees ). Maximum percent count differences were 10% +/- 16% between torsion-corrected versus uncorrected perfusion maps. The greatest wall thickening differences were seen for patients with left ventricular apical aneurysms and for patients after CABG versus group 1 (10% +/- 6% and 8% +/- 6% vs 3% +/- 1%, respectively). CONCLUSIONS: It is feasible to detect cardiac torsion in the majority of Tc-99m sestamibi myocardial perfusion scans. Abnormal twisting patterns distinguished patients after CABG and those with left ventricular aneurysms from subjects with normal perfusion in a manner similar to magnetic resonance imaging observations.     

The role of first-pass radionuclide angiography in the era of gated SPECT myocardial perfusion imaging

Summary  All is not bleak as to the future of RNA, but to do it right, we need to approach it based on evidence gleaned from well-conducted clinical studies. Only then will we determine the added value of exercise EF over MPI in patient management.     

Influence of arrhythmias on gated SPECT myocardial perfusion and function quantification.

Despite the importance of R-wave gating myocardial perfusion tomography for ventricular function assessment, neither prevalence of gating errors nor their influence on quantified cardiac parameters has been studied. METHODS: Arrhythmia-induced anomalies in curves of counts versus projection angle for each R-wave segment were detected visually and algorithmically. Arrhythmia prevalence was tabulated for 379 patients (group 1) with prospective coronary artery disease (mean age 63+/-13 y, 47% male). Myocardial counts were analyzed from all reconstructed cinematic midventricular slices to assess arrhythmia effects on percentage of systolic count increase, generally assumed to equal percentage of wall thickening. In a separate retrospective analysis of 41 patients (group 2), with coronary artery disease (mean age 64+/-12 y, 68% male) having no significant arrhythmias, 36 of whom also underwent equilibrium radionuclide angiography, original projection data were altered to simulate arrhythmia-induced aberrant count patterns to evaluate effects on ventricular function and perfusion measurements. RESULTS: Group 1 patients consisted of 26% without gating errors, 32% with count losses only in the last R-wave interval due to inconsistent transient increase of heart rate, 24% with count decreases in several late intervals due to consistently variable rates, 8% with early interval count increases paired with late interval count decreases due to ectopic beats and 9% with erratic count changes due to atrial fibrillation. Observed count patterns were strongly associated (P < 10(-3)) with arrhythmias detected by electrocardiogram monitoring. In group 2 simulations, ventricular volumes changed by only 2%+/-9% and ejection fraction (EF) by only 1%+/-4% from control values and correlated linearly (r> or = 0.96) with control values for all simulated arrhythmias. SPECT and equilibrium radionuclide angiography EFs correlated similarly (r = 0.85-0.89) for control and all simulations. Percentage changes from control in perfusion defect extent and severity were larger than processing reproducibility limits, the largest change being for atrial fibrillation. Control wall thickening was 38%+/-17%, significantly lower (P < 10(-6)) than for simulated arrhythmias, reflecting similar observations for group 1 patients. CONCLUSION: Even though ventricular volumes and EFs were affected minimally by arrhythmias, both perfusion analysis and wall thickening were compromised. Consequently, quality assurance of gating may be critically important for obtaining accurate quantified parameters.     

Transient postischemic stunning evaluation by stress gated Tl-201 SPECT myocardial imaging: Effect on systolic left ventricular function

BACKGROUND: Transient postischemic stunning (TIS) has been reported in images obtained (1/2) to 1 hour after stress with technetium 99m tracers but has not been investigated in images obtained shortly after stress with thallium 201. We also quantified the global extent and severity of TIS, which has not been done previously. METHODS AND RESULTS: We evaluated 82 patients with either treadmill or dobutamine stress Tl-201 myocardial perfusion imaging. Images were semiquantitatively examined with a 20-segment model. The extent and severity of myocardial ischemia and TIS were assessed by the summed difference score from the early and delayed scores of perfusion, wall motion (WM), and wall thickening (WT). The mean left ventricular ejection fraction (LVEF) was significantly lower in early images than in delayed images in patients with ischemia (P <.01), TIS by WM (P <.001), and TIS by WT (P <.001), and the LVEF difference was more significantly different as the summed difference score of perfusion, WM, or WT increased. No significant LVEF difference was seen in patients with ischemia who did not have TIS. CONCLUSIONS: In stress gated Tl-201 single photon emission computed tomography myocardial perfusion imaging, early TIS is frequently seen in patients with ischemia and is equivalently detected by WM and WT assessments. Significant exercise-induced transient left ventricular global dysfunction is associated with more severe and extensive ischemia and can be predicted by the measurement of the extent and severity of TIS from the same images.     

Increased prognostic value of combined myocardial perfusion SPECT imaging and the quantification of lung Tl-201 uptake

PURPOSE: The authors wanted to identify those patients assessed by exercise SPECT in whom the quantification of lung Tl-201 uptake helps to evaluate disease prognosis. METHODS: One hundred forty-nine patients (114 men, 35 women; 74 after myocardial infarction [MI]; mean age, 54 +/- 9 years) underwent exercise Tl-201 SPECT. The SPECT patterns were divided into normal (n = 45), fixed defects (n = 29), and inducible ischemia (n = 75). Anterior planar imaging was performed before SPECT acquisition to calculate the lung-to-heart ratio (L:H). RESULTS: During an average follow-up of 20 +/- 9 months, eight patients had died of cardiac causes and 13 patients experienced nonfatal MIs. Among the 45 patients with normal perfusion, no cardiac event was observed and the L:H ratio was not helpful for risk stratification. In 29 patients with fixed defects, four cardiac deaths occurred (all in patients with L:H ratios >0.5; annual event rate, 21.1% for L:H ratios >0.5 compared with 0% for L:H ratios <0.5; chi-square = 4.07, P < 0.05). Among the 75 patients with ischemia, 4 died and 13 had nonfatal MIs (annual event rate, 15.4% for L:H ratios >0.5 compared with 13% for L:H ratios <0.5; P = NS). CONCLUSIONS: These findings suggest a benign prognosis in patients with normal SPECT (regardless of the L:H ratio). Conversely, all patients with ischemia are at high risk for future cardiac events. Quantification of the Tl-201 lung uptake seems to be valuable in evaluations of disease prognosis, especially in patients with fixed defects.     

SPECT imaging with Tl-201 and Ga-67 in myocardial sarcoidosis

Two patients with myocardial sarcoidosis are presented, both of whom underwent SPECT imaging with Tl-201 and Ga-67. The first had Ga-67 myocardial uptake with a Tl-201 defect, which disappeared with corticosteroid therapy. The second had multiple Tl-201 defects without Ga-67 uptake, which persisted despite corticosteroid therapy. Therefore, the combination of Tl-201 and Ga-67 imaging may be useful for recognizing myocardial sarcoidosis and for predicting the response to corticosteroid therapy.     

Rest versus stress ejection fraction on gated myocardial perfusion SPECT

OBJECTIVES: It is widely accepted that exercise-induced stunning has an impact on left ventricular ejection fraction (EF); yet, despite the recommendations of the American Society of Nuclear Cardiology, many departments only perform gated SPECT on stress studies. The aim of this investigation was to determine the relationship between rest EF and stress EF in myocardial perfusion studies and to identify possible predictors of variability. METHODS: This study was a retrospective cross-sectional study of 133 patients (266 studies) undergoing myocardial perfusion SPECT. Automated computer-generated functional data (end-diastolic volume, end-systolic volume [ESV], and EF) for rest and stress studies were correlated as matched pairs and analyzed with respect to the following variables: age, sex, stress method, time between stress and scanning, and presence or absence of pathology scintigraphically. Differences in matched EF pairs (DeltaEF) and transient dilatation were also determined. RESULTS: Matched pairs of rest EF and stress EF demonstrated excellent correlation (0.90) with no significant difference noted (P=0.15). Bland-Altman analysis demonstrated a mean DeltaEF of -0.65% (95% confidence interval [CI], -1.54% to 0.23%) with 94% of data points within the 95% limits of agreement. No statistically significant difference was determined between the mean DeltaEF and the hypothetic mean of 0 (P=0.15). A time between stress and scanning of <45 min was shown to be predictive of a negative DeltaEF (P=0.04). Transient dilatation was shown to be predictive of a negative DeltaEF (P=0.01). Resting ESVs between 25 and 50 mL were shown to be predictive of a negative DeltaEF (P=0.02). A stress EF of <50% was also shown to be predictive of a negative DeltaEF (P=0.003). CONCLUSION: No statistically significant difference between stress and rest EF was demonstrated and no trend was identified toward either under- or overestimation of the stress EF with a DeltaEF. A negative DeltaEF was, however, predicted by transient dilatation of >1.0, a time between stress and scanning of <45 min, a stress EF of <50, and an ESV between 25 and 50 mL. Gated SPECT performed on both stress and rest studies may provide a mechanism to predict exercise-induced stunning and transient dilatation.     

Effect of perfusion pattern and imaging sequence on gated perfusion SPECT evaluation of myocardial stunning.

The aim of this study was to determine the effect of perfusion defect and imaging sequence on the evaluation of myocardial stunning with gated perfusion SPECT. METHODS: A dynamic mathematic cardiac torso phantom was used to create 100 gated SPECT simulations (50 stress-rest and 50 rest-stress sequences) with a wide range of perfusion defects. No segmental wall motion abnormalities were created. After generating projection images, 2 additional acquisitions were simulated by thresholding the projected data to 25% and 75% of the maximum. Finally, gated SPECT projections were grouped by 2s to generate 2 series of phantoms corresponding to stress-rest and rest-stress imaging sequences. For each sequence, the first dataset was the 25% thresholded gated SPECT. Both 75% thresholded and 100% signal intensity were used as a second dataset. Each simulated gated SPECT image differed from others in the extent of myocardial scar or ischemia, but all had the same end-diastolic volume (EDV) (125 mL), end-systolic volume (ESV) (48 mL), and ejection fraction (EF) (62%). Left ventricular perfusion and function were each assessed using validated software. RESULTS: Mean stress EDV was decreased when compared with rest-simulated data (111 +/- 4.7 and 112.4 +/- 4.8 mL, respectively; P < or = 0.05), and mean stress ESV was increased when compared with rest-simulated data (44 +/- 4.2 and 42.7 +/- 4 mL, respectively; P < 0.02). The resulting mean stress EF was decreased in the same comparison (60.3% +/- 3.1% and 62% +/- 2.7%, respectively; P = 0.0001). After multivariate analysis, the difference between stress and rest EF was significantly influenced by myocardial infarction (P = 0.0027), severe extent of myocardial ischemia (P = 0.0017), and imaging sequence (P < 0.0001). A > or =5% decrease in EF on stress SPECT (i.e., myocardial stunning) was significantly associated with the stress-rest sequence (chi(2) = 26; P < 0.0001). CONCLUSION: Perfusion defects and imaging sequence had significant effects on the evaluation of myocardial stunning using gated perfusion SPECT.     

Consideration of perfusion reserve in viability assessment by myocardial Tl-201 rest-redistribution SPECT: A quantitative study with dual-isotope SPECT

BACKGROUND: To optimize the use of thallium 201 rest-redistribution study in Tl-201/technetium 99m sestamibi dual-isotope single photon emission computed tomography (SPECT), the predictability of Tl-201 rest-redistribution for viable myocardium was examined according to the degree of perfusion reserve. METHODS AND RESULTS: Twenty patients with both unstable angina and left ventricular dysfunction were enrolled. Tl-201 rest-dipyridamole stress Tc-99m sestamibi gated SPECT/Tl-201 24-hour redistribution SPECT was performed before and 3 months after coronary artery bypass grafting. Through use of a 20-segment model, segmental stress perfusion, rest perfusion, and systolic thickening were quantified on gated SPECT by means of automatic quantitation software. Perfusion was expressed as the average percentage of maximal radioactivity uptake. To represent perfusion reserve, the perfusion difference score (PDS) was defined as rest perfusion minus stress perfusion. A low PDS indicated little or no inducible ischemia, and a high PDS indicated inducible ischemia. In dysfunctional myocardium, viability was defined by the improvement of thickening after coronary artery bypass grafting. The overall predictability of Tl-201 redistribution for viability was 0.709 of the area under the curve (AUC) in receiver operating characteristic analysis. With a cutoff of 7, predictability was significantly better in the low PDS group (AUC = 0.785) than in the high PDS group (AUC = 0.582). CONCLUSIONS: The predictability of Tl-201 rest-redistribution for viability differs according to perfusion reserve. It was more reliable for dysfunctional myocardium with persistent perfusion decrease. On the basis of the continuum hypothesis of chronic stunning and hibernation, we suggest that dysfunctional myocardium with persistent perfusion decrease should be assessed by Tl-201 redistribution SPECT.     

Quantitative gated SPECT myocardial perfusion imaging with 201Tl: an assessment of the limitations

Gated SPECT (GSPECT) perfusion imaging has been increasing in popularity both with 99Tc(m) agents and 201Tl. However, both higher activities than administered in the UK and multi-headed cameras are often used. The aim of this study was to assess GSPECT imaging using lower activities of 201Tl with a single-headed camera. Seventy patients underwent stress and redistribution GSPECT imaging after a mean injected activity of 62 +/- 7 MBq 201Tl. These patients also underwent radionuclide ventriculography (RNVG) imaging. The Cedars Sinai Quantitative Gated SPECT (QGS) package was used to calculate left ventricular ejection fraction (LVEF) from the GSPECT studies. Comparison of ejection fractions calculated using GSPECT with those calculated using RNVG yielded a correlation coefficient of 0.70 for the stress studies and 0.71 for the redistribution studies. The width of the mean 95% prediction interval ranged from 22 to 74 percentage points for the stress studies and 22 to 86 percentage points for the redistribution studies. Ejection fractions calculated from stress and redistribution GSPECT studies showed a correlation of 0.80 with a mean 95% prediction interval of 42.6 +/- 0.4 percentage points. In conclusion, left ventricular ejection fractions calculated using the QGS algorithm from 201Tl GSPECT studies are inadequate for use in clinical practice.     

定量门控201Tl心肌显像对冠心病患者的预后价值

目的 研究定量门控201Tl心肌显像对冠心病患者预后评估及冠心病治疗方案选择的价值.方法 对84例患者进行静息和运动负荷201Tl门控心肌灌注SPECT显像,并随访(32.92±16.77)个月.对心肌灌注图像进行评分(1～4分),计算总负荷评分(SSS)、总静息评分(SRS)和总差值分(SDS=SRS-SSS)、负荷左室射血分数(EF)值和静息EF值.结果 随访中9例发生心脏事件,年发生率为3.90%.SSS、SDS、SRS以及EF值均是心脏事件的独立预测因素(P＜0.005).Cox比例风险回归分析示SSS是心脏事件的最强预测因素.根据患者的负荷后EF值、SDS等可将患者分为低危、中危和高危组.结论 应用定量门控201Tl心肌显像可以对冠心病患者进行正确的预后评估,并可指导选择治疗方案.SSS是心脏事件的最强预测因素.     

A transformation cross-talk technique for simultaneous dual radionuclide imaging: a myocardial perfusion 201Tl/99Tcm sestamibi dog SPECT study

We have developed a novel transformation method for the correction of cross-talk in simultaneous dual radionuclide single photon emission CT (SPECT) imaging. It is based on the assumption that the transformations, which transform the primary energy window images into the scatter images as viewed in the other energy windows, are known. The method was tested on a dog model. These transformations were found by measuring the point response functions (prf) in different energy windows for both radionuclides in water. The dual radionuclide correction method described takes into account the different spatial distributions of the primary and scatter cross-talk photons in different energy windows. This method also includes the sequential application of restoration filters to the resulting cross-talk corrected images. We used a dog model in three separate studies: two single radionuclide studies used as references and one dual radionuclide study. Contrast between the left ventricular cavity (LVC) and the myocardium was used in horizontal long axis (HLA) slices as a parameter to evaluate the results of the dual radionuclide correction method with restoration. The increase of the contrast in the dual radionuclide corrected images in both energy windows, i.e. 201Tl primary window (70 keV) and 99Tcm primary window (140 keV), was significant. The cross-talk corrected 70 keV dual radionuclide HLA slice had a contrast of 0.62 compared with 0.35, which was the value in the non-corrected dual radionuclide HLA slice. Restoration improved the contrast to 0.68. In the single radionuclide 201Tl image, the same contrast was 0.59, improving to 0.70 after restoration. For the dual radionuclide 140 keV HLA slice, the contrast increased from 0.69 to 0.76 after cross-talk correction. Additional increase of the contrast to 0.83 resulted from restoration filtering. In the single radionuclide 99Tcm sestamibi 140 keV HLA slice the improvement of contrast was from 0.63 to 0.86 as a result of the restoration. The transformation three-window, dual radionuclide correction method with restoration improves the quality of the simultaneous rest 201Tl/stress 99Tcm sestamibi SPECT imaging.     

Estimate of myocardial salvage in late presentation acute myocardial infarction by comparing functional and perfusion abnormalities in predischarge gated SPECT

Purpose We hypothesized that, because of persistent stunning, the extent of post-treatment functional abnormalities detected using gated single-photon emission computed tomography (SPECT) could be representative of the initial risk area in acute myocardial infarction (AMI) treated by reperfusion therapy. Materials and methods In 48 AMI patients, we acquired two ^99mTc-sestamibi gated SPECT studies (at admission with tracer injection before treatment and at discharge 5 to 10 days later). We assessed the myocardial salvage defined by the admission minus predischarge summed rest score, and we compared it with the value obtained by subtracting the extent of perfusion defect from the extent of wall motion or wall thickening abnormalities in predischarge gated SPECT. Myocardial salvage was expressed as salvage index (salvaged myocardium divided by initial risk area). Results There was a good correlation between summed rest score salvage index and wall motion (Spearman’s ρ = 0.754, p < 0.0001) or wall thickening salvage index (Spearman’s ρ = 0.798, p < 0.0001). The wall thickening salvage index was able to classify correctly the patients that had a summed rest score salvage index ≥ 0.10 with 73% sensitivity, 88% specificity, and 83% accuracy. The wall motion salvage index was highly sensitive (91%) but poorly specific (13%, p < 0.002 vs wall thickening salvage index) and less accurate (69%, p < 0.05 vs wall thickening salvage index). Conclusions ^99mTc-sestamibi gated SPECT allows assessing myocardial salvage using only post-treatment data. The salvage index derived using wall thickening as surrogate of admission perfusion defect correlates well with the salvage index measured by comparing pre- and post-treatment perfusion defects.