Myocardial tracking, a new method to calculate ejection fraction with gated SPECT: validation with (201)Tl versus planar angiography.

Left ventricular ejection fraction (LVEF) and viability are essential variables for the prognosis of myocardial infarction and can be measured simultaneously by (201)Tl gated SPECT; however, most algorithms tend to underestimate LVEF. This study aimed to evaluate a new myocardial tracking algorithm, MyoTrack (MTK), for automatic LVEF calculation. METHODS: A rest/redistribution (20 min/4 h) (201)Tl gated SPECT protocol followed immediately by a (99m)Tc equilibrium radionuclide angiography (ERNA) was performed in 75 patients with history of myocardial infarction. Quality of myocardial uptake was evaluated from count statistics and automatic quantification of defect sizes and severities (CardioMatch). LVEFs were calculated both with Germano's quantitative gated SPECT (QGS) algorithm and with MTK. Briefly, the originality of this algorithm resides in the unique end-diastole segmentation, matching to a template and motion field tracking throughout the cardiac cycle. RESULTS: ERNA LVEF averaged 33% +/- 14%. QGS significantly underestimated this value at 20 min (30% +/- 13%, P < 0.001) and at 4 h (30% +/- 13%, P < 0.0001). By contrast, MTK did not miscalculate LVEF at 20 min (34% +/- 14%, probability value was not significant) though a similar underestimation occurred at 4 h (31% +/- 13%, P < 0.02). Individual differences between early and late gated SPECT values and differences between gated SPECT and ERNA values did not correlate with the extension of perfusion defects, count statistics, or heart rate. CONCLUSION: MTK algorithm accurately calculates LVEF on early/high-count images compared with ERNA [corrected], even in patients with severe perfusion defects, but tends to underestimate LVEF on delayed/low-contrast images, as other algorithms do.     

Assessment of ejection fraction with Tl-201 gated SPECT in myocardial infarction: Precision in a rest-redistribution study and accuracy versus planar angiography

BACKGROUND. Viability and left ventricular ejection fraction (LVEF) are essential measures for the assessment of myocardial infarction (MI). These 2 variables may be evaluated simultaneously by means of thallium-201 gated single photon emission computed tomography (SPECT); however, the precision and accuracy of LVEF measurements with this isotope remain controversial, particularly in cases of extended perfusion defects and poor count densities. METHODS AND RESULTS. Fifty patients with a history of MI underwent a 20-minute rest and a 4-hour redistribution Tl-201 gated SPECT viability protocol, immediately followed by a technetium-99m planar equilibrium radionuclide angiography (ERNA). On gated SPECT images, various count statistics were calculated, and perfusion was automatically quantified by means of CardioMatch, which provided both the size and severity of MI defects. Rest and redistribution LVEFs were determined from gated SPECT with Germano's algorithm, whereas LVEFs were calculated from ERNA using the manufacturer's software. Mean LVEF values calculated with rest gated SPECT, redistribution gated SPECT, and planar ERNA were 30% +/- 13%, 30% +/- 13% and 33% +/- 13%, respectively. Significant differences between repeated gated SPECT LVEFs were not shown by means of the paired t test. Correlation coefficients were high between 20-minute and 4-hour scans (r = 0.89) and between gated SPECT and ERNA (r = 0.88 and r = 0.92 at 20 minutes and 4 hours, respectively). Additionally, close agreement between gated SPECT and ERNA was shown by means of the Bland-Altman plot, despite an underestimation of 3 units. Finally, neither the technical conditions (count density, heart rate, lung uptake, etc) nor the perfusion alteration (size, severity, redistribution) appeared to interfere with the precision and accuracy of gated SPECT LVEF measurement. CONCLUSION. Tl-201 gated SPECT is a precise method for assessing LVEF within the same patient at 4-hour intervals, even with a substantial count decay, and it gives accurate results compared with planar ERNA, even in the case of large perfusion defects.     

Factors affecting left ventricular ejection fraction using automated quantitative gated SPECT

BACKGROUND: Factors affecting the accuracy of left ventricular ejection fraction (LVEF) quantification using automated quantitative gated SPECT have not been adequately investigated in patients in the clinical setting. Therefore, the authors studied the effect of defect size and Tc-99m tetrofosmin dose on the accuracy of LVEF calculation using the automated QGS program. MATERIALS AND METHODS: Thirty-two consecutive patients underwent gated rest and stress myocardial perfusion SPECT after administration of 8 and 27 mCi Tc-99m tetrofosmin, respectively. The LVEF was obtained for both the rest and stress studies using the QGS program and compared with the LVEF obtained using quantitative echocardiography performed within 2 weeks. Myocardial perfusion defects were recorded as scarring, ischemia, or mixed scarring and ischemia in 12 left ventricular segments. The defect size was evaluated by adding the number of affected segments. RESULTS: The mean LVEF calculated using high-dose stress QGS, low-dose rest QGS, and echocardiography was 49.2% +/- 15%, 46.2% +/- 17% and 48.7% +/- 16.9% respectively, with no statistically significant differences. The LVEF obtained using high-dose stress QGS correlated better with echocardiography than did that obtained using low-dose rest QGS (r = 0.86 versus 0.76). In addition, when the high-dose stress LVEF in the 14 patients with normal myocardial perfusion was compared with that in 11 patients who had one- or two-segment perfusion defects, and 7 patients who had perfusion defects in > or = three segments, there was good correlation with echocardiography in the three patient groups (r = 0.85, 0.88, and 0.91, respectively). CONCLUSIONS: Myocardial perfusion defects do not affect the accuracy of LVEF calculation using automated QGS. High-dose gated myocardial SPECT demonstrated better correlation with quantitative echocardiography LVEF results.     

Assessment of left ventricular function by 201Tl ECG-gated myocardial SPECT]

We applied the QGS program for LV function analysis (described by Germano, 1995) to a 201Tl SPECT study at rest, and estimated its accuracy. We performed 201Tl ECG-gated myocardial SPECT in 25 patients with ischemic heart disease under an acquisition time used in the routine 99mTc ECG-gated SPECT study. The quality of the gated images was visually assessed with a 4-point grading system. LVEDV, LVESV, LVEF determined by the QGS program were compared with those by Simpson's method on biplane LVG in 25 patients. Regional wall motion scores in 7 myocardial segments were assessed on the three-dimensional display created by the QGS program and the cine display of biplane LVG with a 5-point grading system. Wall motion scores obtained by the QGS program were compared with those by LVG. Although 72.0% of 201Tl ECG-gated SPECT images were fair or poor in image quality, there were good correlations between the values obtained by the QGS program and LVG (LVEDV: r = 0.82, LVESV: r = 0.88, LVEF: r = 0.89). In addition, wall motion scores by the QGS program were correspondent to those by LVG in 77.1% of all 175 myocardial segments. We conclude that the QGS program provides high accuracy in evaluating left ventricular function even from 201Tl ECG-gated myocardial SPECT data.     

Segmental analysis of SPECT 99mTc-methoxy isobutyl isonitrile and 201Tl myocardial imaging in ischaemic heart disease

To study the potential usefulness of 99mTc-methoxy isobutyl isonitrile (99mTc-MIBI) as a substitute for 201Tl in assessing patients with ischaemic heart disease, 24 patients underwent 1 day rest and exercise 99mTc-MIBI single photon emission computerised tomography (SPECT) 1 week after SPECT exercise 201Tl. All patients were catheterized within 1 month after myocardial imaging. In 17 patients, resting first pass radionuclide angiography (FPRNA) was performed with 99mTc-MIBI. The heart to lung ratio for 99mTc-MIBI and 201Tl was calculated both at rest and exercise. The segmental analysis for myocardial perfusion reveals that 87/96 segments (91%) were correctly classified by SPECT 201Tl and 84/96 segments (88%) were correctly classified by 99mTc-MIBI. A significant correlation was present between LVEF measured by 99mTc-MIBI FPRNA and contrast ventriculography (r = 0.85, P less than 0.0001). The heart to lung ratio both at rest and exercise for 99mTc-MIBI is significantly higher than 201Tl (P less than 0.01 and less than 0.001 respectively). We conclude that 99mTc-MIBI is a promising agent for simultaneous evaluation of myocardial perfusion and cardiac function.     

201Tl定量门控心肌灌注体层显像与99mTc-红细胞门控心血池显像测定左心室射血分数的对比研究

目的 探讨201Tl定量门控心肌灌注体层显像与99mTc-红细胞门控心血池显像测量左心室射血分数(LVEF)的相关性.方法 72例受检者接受201Tl静息门控心肌灌注体层显像,用AUTOQUANT 4.21软件测量LVEF,并与24 h内的静息99mTc-红细胞平衡法门控心血池显像结果进行比较.结果 ①门控心肌灌注体层显像与门控心血池显像测量LVEF值的结果呈明显正相关(r=0.554,P=-0.000),两种方法无统计学差别(t=1.194,P＞0.05).②不同疾病组之间两种测量方法无统计学差异(P值均大于0.05).③门控心肌灌注体层显像及门控心血池显像测量的LVEF值分别为(64.68±10.77)%和(62.46±8.99)%,门控心肌灌注体层显像测量的LVEF值要比门控心血池显像高出3.55%.结论 201Tl门控心肌灌注体层显像与99mTc-红细胞门控心血池显像测量LVEF值的相关性好且结果准确,但门控心肌灌注体层显像的LVEF测量值要稍高于门控心血池显像.     

Day-to-day variability of global left ventricular functional and perfusional measurements by quantitative gated SPECT using Tc-99m tetrofosmin in patients with heart failure due to coronary artery disease

BACKGROUND: Although myocardial gated single photon emission computed tomography (SPECT) is routinely used for functional measurements in patients with coronary artery disease (CAD) and heart failure, day-to-day variability of left ventricular ejection fraction (LVEF), left ventricular (LV) volumes, and global perfusion scoring has not yet been investigated. METHODS AND RESULTS: In 20 consecutive patients with CAD and an LVEF lower than 40% who routinely underwent a resting tetrofosmin gated SPECT study, we performed an additional gated SPECT study at rest 1 to 5 days later under the same circumstances. LV volumes and LVEF were calculated from the gated SPECT data by commercially available software (QGS). Myocardial perfusion was scored visually by use of a 20-segment, 5-point scoring method. For global LV function and perfusion, agreement between data was investigated by use of Bland-Altman plotting. The 95% limits of agreement found by Bland-Altman analysis were -0.9% +/- 6.0% for LVEF, 3 +/- 20 mL for LV end-diastolic volume, and 4 +/- 20 mL for LV end-systolic volume. CONCLUSION: In CAD patients with an LVEF lower than 40%, day-to-day variability of measurements of global myocardial function and perfusion is quite similar to interobserver and intraobserver variability. Day-to-day variability of global LV functional parameters obtained by gated cardiac SPECT is fairly small, which indicates that myocardial gated SPECT can be used in daily clinical practice to determine changes in global LV function and perfusion over time in patients with diminished LV function.     

Effect of temporal sampling on evaluation of left ventricular ejection fraction by means of thallium-201 gated SPET: comparison of 16- and 8-interval gating, with reference to equilibrium radionuclide angiography

Gated myocardial single-photon emission tomography (SPET) allows the evaluation of left ventricular ejection fraction (LVEF), but temporal undersampling may lead to systolic truncation and ejection fraction underestimation. The aim of this study was to evaluate the impact of temporal sampling on thallium gated SPET LVEF measurements. Fifty-five consecutive patients (46 men, mean age 62+/-12 years) with a history of myocardial infarction (anterior 31, inferior 24) were studied. All patients underwent equilibrium radionuclide angiography (ERNA) and gated SPET 4 h after a rest injection of 185 MBq (5 mCi) of thallium-201 using either 8-interval (group 1, n=25) or 16-interval gating (group 2, n=30). In group 2, gated SPET acquisitions were automatically resampled to an 8-interval data set. Projection data were reconstructed using filtered back-projection (Butterworth filter, order 5, cut-off 0.20). LVEF was then calculated using commercially available software (QGS). A higher correlation between gated SPET and ERNA was obtained with 16-interval gating (r=0.94) compared with the resampled data set (r=0.84) and 8-interval gating (r=0.71). Bland-Altman plots showed a dramatic improvement in the agreement between gated SPET and ERNA with 16-interval gating (mean difference: -0.10%+/-5%). Using multiple ANOVA, temporal sampling was the only parameter to influence the difference between the two methods. When using 8-interval gating, gated SPET LVEF was overestimated in women and underestimated in men (ERNA minus gated SPET = -4.0%+/-9.6% in women and 3.6%+/-7.6% in men, P=0.01). In conclusion, 16-interval thallium gated SPET offered the best correlation and agreement with ERNA, and should be preferred to 8-interval gated acquisition for LVEF measurement.     

Limited performance of quantitative assessment of myocardial function by thallium-201 gated myocardial single-photon emission tomography

We investigated the reproducibility between thallium-201 and technetium-99m methoxyisobutylisonitrile (MIBI) gated single-photon emission tomography (SPET) for the assessment of indices of myocardial function such as end-diastolic and end-systolic volume (EDV, ESV), ejection fraction (EF) and wall motion. Rest 201Tl (111 MBq) gated SPET was sequentially performed twice in 20 patients. Rest 201Tl gated SPET and rest 99mTc-MIBI (370 MBq) gated SPET were performed 24 h apart in 40 patients. Wall motion was graded using the surface display of the Cedars quantitative gated SPET (QGS) software. EDV, ESV and EF were also measured using the QGS software. The reproducibility of functional assessment on rest 201Tl gated SPET was compared with that on 99mTc-MIBI gated SPET, and also with that between 201Tl gated SPET and 99mTc-MIBI gated SPET performed on the next day. The two standard deviation (2 SD) values for EDV, ESV and EF on the Bland-Altman plot were 29 ml, 19 ml and 12%, respectively, on repeated 201Tl gated SPET, compared with 14 ml, 11 ml and 5.3% on repeated 99mTc-MIBI gated SPET. The correlations were good (r=0.96, 0.97 and 0.87) between the two measurements of EDV, ESV and EF on repeated rest studies with 201Tl and 99mTc-MIBI gated SPET. However, Bland-Altman analysis revealed that the 2 SD values between the two measurements were 31 ml, 23 ml and 12%. We were able to score the wall motion in all cases using the 3D surface display of the QGS on 201Tl gated SPET. The kappa value of the wall motion grade on the repeated 201Tl study was 0.35, while that of the wall motion grade on the repeated 99mTc-MIBI study was 0.76. The kappa value was 0.49 for grading of wall motion on repeated rest studies with 201Tl and 99mTc-MIBI. In conclusion, QGS helped determine EDV, ESV, EF and wall motion on 201Tl gated SPET. Because the EDV, ESV and EF were less reproducible on repeated 201Tl gated SPET or on 201Tl gated SPET and 99mTc-MIBI gated SPET on the next day than on repeated 99mTc-MIBI gated SPET, functional measurement on 201Tl gated SPET did not seem to be interchangeable with that on 99mTc-MIBI gated SPET.     

Accuracy of the automated assessment of left ventricular function with gated perfusion SPECT in the presence of perfusion defects and left ventricular dysfunction: Correlation with equilibrium radionuclide ventriculography and echocardiography

BACKGROUND: Gated single photon emission computed tomography (SPECT) with automated methods allows the quantitative assessment of left ventricular function and perfusion; however, its accuracy must be defined for patients with large earlier infarctions and severe rest perfusion defects, in whom the estimation of endocardial and epicardial borders might be more difficult, even with automated edge-detection techniques. METHODS AND RESULTS: We prospectively compared the automated measurements of left ventricular ejection fraction (LVEF) and volumes from rest-injected gated Technetium 99m (Tc99m) perfusion SPECT with equilibrium radionuclide angiocardiography (ERNA) in 62 patients and the assessment of regional function with echocardiography in 22 patients. Forty-six patients had an earlier myocardial infarction (mean defect size, 34% of left ventricle; SD, 12.7%; range, 8% to 56%); 27 patients had large defects (> or = 20% of left ventricle; LVEF range, 8% to 75%). LVEF, as determined with Cedars-Sinai software (quantitative gated SPECT), correlated well with ERNA (r = 0.941; y = 1.003x + 1.15; P<.0001; SE of the estimate = 6.3%; mean difference -1.3% for LVEF) in the entire study population and in the subgroups of patients with an earlier infarction, severe defects, and large infarctions (> or = 20% of the left ventricle). A correlation existed between gated SPECT and ERNA volumes (r = 0.882, y = 1.040x - 14.7, P<.0001 for end-diastolic volume; r = 0.954, y = 1.147x - 13.9, P<.0001 for end-systolic volumes with the count-ratio technique), but with wider limits of agreement. The exact segmental score agreement between gated SPECT and echocardiography for regional function was 79.8% (281 of 352, kappa = 0.682). CONCLUSIONS: Automated gated SPECT provides an accurate assessment of ejection fraction and regional function, even in the presence of an earlier myocardial infarction with large perfusion defects and significant left ventricular dysfunction.     

Comparison of left ventricular function at rest and post-stress in patients with myocardial infarction: Evaluation with gated SPECT

BACKGROUND. Quantitative electrocardiogram-gated single photon emission computed tomography (SPECT) myocardial imaging (QGS) is a means of providing functional information about the left ventricle and myocardial perfusion. However, the functional information derived 30 minutes post-stress may be different from the left ventricular (LV) function determined at rest. This study determined whether LV function post-stress would be different from LV function at rest in patients with an earlier myocardial infarction. METHODS AND RESULTS. LV perfusion and ejection fraction (LVEF), were determined by means of both the rest and post-stress acquisition in 58 patients with an earlier myocardial infarction and in 23 patients with a low likelihood of coronary artery disease by using technetium-99m tetrofosmin and the QGS program. The interobserver and intraobserver variability of LVEF was excellent, within a margin of 2%. No significant differences in LVEF were observed between post-stress and rest in the 23 patients with a low likelihood of disease (DeltaLVEF, 0.04% +/- 3.2%, P = not significant). Conversely, the patients with an earlier myocardial infarction showed a significantly lower LVEF post-stress, compared with that at rest (DeltaLVEF, -1.9% +/- 4.2%, P =.002). In 33 patients (57%), the LVEF post-stress was 2% or more lower than the LVEF at rest. Furthermore, reversible ischemia, which was present in 16 patients (28%), did not interact with the DeltaLVEF post-stress, compared with the DeltaLVEF at rest (P = not significant). Parameters such as the stress modality (adenosine stress or exercise), the number of stenosed vessels, or the perfusion defect severity score did not influence the DeltaLVEF post-stress, compared with the DeltaLVEF at rest. CONCLUSIONS. In patients with an earlier myocardial infarction, LV function post-stress may not represent the true resting LV function. Consequently, this result justifies the stratification of patients before starting the gated SPECT study. In patients with an earlier myocardial infarction, the gated acquisition should be performed during the rest study.     

Assessment of left ventricular function by 201Tl SPECT using left ventricular cavity-to-myocardium count ratio

Equilibrium radionuclide angiography (ERNA) is the 'gold standard' for assessing left ventricular ejection fraction (LVEF). The aim of the study was to determine whether the left ventricular cavity-to-myocardium count ratio (LVCMR) from 201Tl myocardial single photon emission computed tomography (SPECT) correlated with LVEF assessed by ERNA. The study group included 159 consecutive patients (117 male, 42 female), aged 59+/-12 years, who underwent both 201Tl SPECT and ERNA at rest on the same day. The LVCMR was calculated from a mid-ventricular short axis slice on redistribution studies, using two regions of interest (ROIs). One ROI was placed in the centre of the left ventricular cavity (C) and the other was placed in the myocardium with maximum uptake (Mmax): LVCMR= (C/Mmax) x 100. The correlation between LVCMR and LVEF was r = 0.85 (y = 0.943x+5.002; P < 0.0001). The mean calculated values +/- 1 SD were LVCMR=54+/-16% and LVEF=52+/-15%. In conclusion, LVCMR from 201Tl SPECT studies was closely correlated with LVEF from ERNA studies and can be used to easily and rapidly estimate left ventricular function.     

Thallium-gated SPECT in patients with major myocardial infarction: effect of filtering and zooming in comparison with equilibrium radionuclide imaging and left ventriculography.

The effect of filtering and zooming on 201TI-gated SPECT was evaluated in patients with major myocardial infarction. METHODS: Rest thallium (TI)-gated SPECT was performed with a 90 degrees dual-head camera, 4 h after injection of 185 MBq 201TI in 32 patients (mean age 61 +/- 11 y) with large myocardial infarction (33% +/- 17% defect on bull's eye). End diastolic volume (EDV), end systolic volume (ESV) and left ventricular ejection fraction (LVEF) were calculated using a commercially available semiautomatic validated software. First, images were reconstructed using a 2.5 zoom, a Butterworth filter (order = 5) and six Nyquist cutoff frequencies: 0.13 (B5.13), 0.15 (B5.15), 0.20 (B5.20), 0.25 (B5.25), 0.30 (B5.30) and 0.35 (B5.35). Second, images were reconstructed using a zoom of 1 and a Butterworth filter (order = 5) (cutoff frequency 0.20 [B5.20Z1]) (total = 32 x 7 = 224 reconstructions). LVEF was calculated in all patients using equilibrium radionuclide angiocardiography (ERNA). EDV, ESV and LVEF were measured with contrast left ventriculography (LVG). RESULTS: LVEF was 39% +/- 2% (mean +/- SEM) for ERNA and 40% +/- 13% for LVG (P = 0.51). Gated SPECT with B5.20Z2.5 simultaneously offered a mean LVEF value (39% +/- 2%) similar to ERNA (39% +/- 2%) and LVG (40% +/- 3%), optimal correlations with both ERNA (r = 0.83) and LVG (r = 0.70) and minimal differences with both ERNA (-0.9% +/- 7.5% [mean +/- SD]) and LVG (1.1% +/- 10.5%). As a function of filter and zoom choice, correlation coefficients between ERNA or LVG LVEF, and gated SPECT ranged from 0.26 to 0.88; and correlation coefficients between LVG and gated SPECT volumes ranged from 0.87 to 0.94. There was a significant effect of filtering and zooming on EDV, ESV and LVEF (P < 0.0001). Low cutoff frequency (B5.13) overestimated LVEF (P < 0.0001 versus ERNA and LVG). Gated SPECT with 2.5 zoom and high cutoff frequencies (B5.15, B5.20, B5.25, B5.30 and B5.35) overestimated EDV and ESV (P < 0.04) compared with LVG. This volume overestimation with TI-gated SPECT in patients with large myocardial infarction was correlated to the infarct size. A zoom of 1 underestimated EDV, ESV and LVEF compared with a 2.5 zoom (P < 0.02). CONCLUSION: Accurate LVEF measurement is possible with TI-gated SPECT in patients with major myocardial infarction. However, filtering and zooming greatly influence EDV, ESV and LVEF measurements, and TI-gated SPECT overestimates left ventricular volumes, particularly when the infarct size increases.     

Transient left ventricular dysfunction is still present one hour after exercise stress test: evaluation by gated SPECT with 99mTc-labeled perfusion agent

It has been reported that quantitative gated SPECT (QGS) has revealed post-stress dysfunction of the left ventricle (LV) 30 minutes after a stress test. The purpose of this study was to determine whether post-stress dysfunction of LV is still present one hour after an exercise stress test. The subjects comprised 152 patients (124 males and 28 females, mean age 59 +/- 10 years). Exercise stress myocardial scintigraphy was performed using a one-day, stress and rest protocol. 99mTc labeled myocardial perfusion tracer, tetrofosmin, 370 MBq was injected at the end-point of a supine ergometer stress test for stress imaging. ECG gated SPECT was carried out 1 hour after injection. Three hours later, 740 MBq to 1100 MBq of 99mTc labeled myocardial perfusion tracer was injected for rest imaging. ECG gated SPECT was again performed 1 hour after injection. We divided the subjects into four groups according to the severity score of defects on the stress image and the presence or absence of fill-in; normal (NOR, n = 59), myocardial infarct (MI, n = 65), small ischemia (S-IS, n = 13) and large ischemia (L-IS, n = 15). Post-stress dysfunction is defined according to two criteria: 1) rest LVEF--post-stress LVEF > or = 5% and 2) post-stress ESV--rest ESV > or = 5 ml. The frequency of post-stress dysfunction was 3.4%, 9.1%, 23.1% and 40% in NOR, MI, S-IS and L-IS, respectively. Post-stress LV dysfunction was found to be more frequent in the large ischemia group. In conclusion, post-stress dysfunction was present 1 hour after the stress test and was more frequent in the large ischemia group.     

201Tl gated single photon emission computed tomographic myocardial perfusion imaging in the assessment of global and regional left ventricular function. Would it be favoured over equilibrium radionuclide angiography?

BACKGROUND: This study investigates the clinical performance of routine 201Tl gated single photon emission computed tomographic (201Tl GSPECT) myocardial perfusion imaging. Equilibrium radionuclide angiography (ERNA) was used as the standard for comparison. METHODS AND RESULTS: One hundred and seventy-two consecutive patients were submitted to both myocardial 201Tl GSPECT imaging, at stress and in redistribution, and ERNA. Left ventricular ejection fractions (LVEF) and regional wall motion were assessed from both stress and redistribution 201Tl GSPECT datasets, and from ERNA. Linear regression analysis showed a good correlation between LVEF calculated by ERNA and 201Tl GSPECT (r=0.73 at stress, r=0.75 in redistribution, P<0.0001). However, the 95% prediction intervals of 201Tl GSPECT LVEF from ERNA LVEF were wide (minimum 35.4% at stress and 33.2% in redistribution). Moreover, a difference in LVEF > or =10% between ERNA and 201Tl GSPECT was found in 26.4% of cases at stress and 28.6% of cases in redistribution. A fair agreement between ERNA and 201Tl GSPECT was found in regional wall motion assessment in segments with normal or mildly reduced tracer uptake (kappa=0.32 at stress and kappa=0.33 in redistribution). In segments with moderately to severely reduced tracer uptake, a moderate agreement was found in regional wall motion assessment between ERNA and 201Tl GSPECT (kappa=0.44 at stress and kappa=0.42 in redistribution). CONCLUSIONS: Left ventricular function may be misinterpreted in a significant proportion of patients if the calculation of LVEF is based on 201Tl GSPECT. Moreover, the evaluation of regional wall motion by 201Tl GSPECT appears unsatisfactory.     

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.     

Left ventricular ejection fraction and volumes on rest gated 201Tl perfusion SPECT: comparison with two-dimensional echocardiography

BACKGROUND: Rest gated 201Tl images are considered to be of poor count statistics due to lower energy and low photon flux of 201Tl in addition to increased attenuation and low dose that can be administered. We compared the left ventricular ejection fraction (LVEF), end diastolic (EDV) and end systolic volume (ESV) obtained on 4 h gated rest 201Tl myocardial perfusion single photon emission computed tomography (SPECT) with those obtained by two-dimensional echocardiography (2-D ECHO) in patients with known or suspected coronary artery disease (CAD). METHODS: Eighty-two consecutive patients who underwent gated 201Tl stress-rest myocardial perfusion SPECT and 2-D ECHO were studied. The gated thallium images were processed with Siemens e-soft autocardiac processor and LVEF, EDV and ESV were evaluated using Emory Cardiac Toolbox. The same parameters were also assessed on the 2-D ECHO using the modified Simpson method for comparison. RESULTS: Out of 82 rest gated images, one study was excluded because of poor count statistics. In 81 (99%) patients there was good linear correlation with 2-D ECHO values and rest gated 201Tl SPECT images for EDV, ESV and LVEF. Pearson's correlation co-efficient (r value) for EDV, ESV and LVEF between the two methods was 0.78, 0.79 and 0.88, respectively. A Bland-Altman plot showed close agreement with LVEF but not for EDV and ESV. CONCLUSION: These results suggest that the 4 h rest gated 201Tl study gives a reliable value for the LVEF compared to 2-D ECHO and can be used in routine clinical practice.     

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: MRI validation and comparison of the Emory Cardiac Tool Box with QGS and 4D-MSPECT.

The goal of this study was to validate the accuracy of the Emory Cardiac Tool Box (ECTB) in assessing left ventricular end-diastolic or end-systolic volume (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SPECT using cardiac MRI (cMRI) as a reference. Furthermore, software-specific characteristics of ECTB were analyzed in comparison with 4D-MSPECT and Quantitative Gated SPECT (QGS) results (all relative to cMRI). METHODS: Seventy patients with suspected or known coronary artery disease were examined using gated (99m)Tc-MIBI SPECT (8 gates/cardiac cycle) 60 min after tracer injection at rest. EDV, ESV, and LVEF were calculated from gated (99m)Tc-MIBI SPECT using ECTB, 4D-MSPECT, and QGS. Directly before or after gated SPECT, cMRI (20 gates/cardiac cycle) was performed as a reference. EDV, ESV, and LVEF were calculated using Simpson's rule. RESULTS: Correlation between results of gated (99m)Tc-MIBI SPECT and cMRI was high for EDV (R = 0.90 [ECTB], R = 0.88 [4D-MSPECT], R = 0.92 [QGS]), ESV (R = 0.94 [ECTB], R = 0.96 [4D-MSPECT], R = 0.96 [QGS]), and LVEF (R = 0.85 [ECTB], R = 0.87 [4D-MSPECT], R = 0.89 [QGS]). EDV (ECTB) did not differ significantly from cMRI, whereas 4D-MSPECT and QGS underestimated EDV significantly compared with cMRI (mean +/- SD: 131 +/- 43 mL [ECTB], 127 +/- 42 mL [4D-MSPECT], 120 +/- 38 mL [QGS], 137 +/- 36 mL [cMRI]). For ESV, only ECTB yielded values that were significantly lower than cMRI. For LVEF, ECTB and 4D-MSPECT values did not differ significantly from cMRI, whereas QGS values were significantly lower than cMRI (mean +/- SD: 62.7% +/- 13.7% [ECTB], 59.0% +/- 12.7% [4DM-SPECT], 53.2% +/- 11.5% [QGS], 60.6% +/- 13.9% [cMRI]). CONCLUSION: EDV, ESV, and LVEF as determined by ECTB, 4D-MSPECT, and QGS from gated (99m)Tc-MIBI SPECT agree over a wide range of clinically relevant values with cMRI. Nevertheless, any algorithm-inherent over- or underestimation of volumes and LVEF should be accounted for and an interchangeable use of different software packages should be avoided.     

Clinical usefulness of ECG-gated18F-FDG PET combined with99mTc-MIBI gated SPECT for evaluating myocardial viability and function

OBJECTIVES: This study sought to evaluate an imaging approach using gated 99mTc-MIBI (MIBI) SPECT and gated 18F-FDG (FDG) PET for assessment of myocardial viability and cardiac function. METHODS: Forty-eight patients (38 men, mean age 68.1 +/- 9.6 years) underwent ECG-gated FDG PET and MIBI SPECT within a week. The baseline diagnoses were coronary artery disease (31), mitral regurgitation (1), paroxysmal arrhythmia (10), and dilated cardiomyopathy (6). The gated FDG PET data were analyzed using pFAST software, and the gated MIBI SPECT data were analyzed using QGS software. Fifteen patients were diagnosed with myocardial infarction, and follow-up study was performed to assess the functional outcome four months later. An improvement in LVEF of >5% was defined as significant. The LV myocardium was divided into 17 segments, and regional defect scores were visually assessed using a 4-point scale for each segment (0 = normal, 1 = mildly reduced, 2 = moderately reduced, 3 = absent). A segment with a greater defect score on MIBI SPECT than on FDG PET was defined as a mismatch. The patients were divided into two groups: those with at least two mismatched segments (MM-group), and those with none or one (M-group). RESULTS: LVEF, EDV and ESV measured by gated FDG PET were highly correlated with those obtained by gated MIBI SPECT (r = 0.848, 0.855 and 0.911, p < 0.0001, respectively). The mean values of LVEF did not differ significantly, but EDV and ESV obtained by gated FDG PET were significantly grater than those obtained by gated MIBI SPECT (p < 0.0001). In 15 patients diagnosed with myocardial infarction, a significant association (p < 0.05) was found between the relative uptake of FDG PET and MIBI SPECT and the functional outcome 4 months later. Global LV function improved in 6 of the 8 patients showing mismatch but in only 1 of the 7 patients with matched defects, resulting in a sensitivity of 86% and specificity of 75%. The overall accuracy to predict global functional outcome was high (80%). CONCLUSION: This imaging approach allows accurate evaluation of myocardial viability. Furthermore, the high correlations of gated FDG PET and gated MIBI SPECT measurements hold promise for the assessment of left ventricular function using gated FDG PET.     

Incremental value of left ventricular ejection fraction for detection of multivessel coronary artery disease in exercise (201)Tl gated myocardial perfusion imaging.

Assessment of reversible defects in exercise (201)Tl perfusion SPECT has low sensitivity and high specificity for detection of multivessel coronary artery disease (CAD). The goal of this study was to evaluate whether the left ventricular ejection fraction (LVEF) in exercise (201)Tl gated SPECT had incremental diagnostic value over perfusion data for detection of multivessel CAD. METHODS: One hundred eighty-two patients underwent exercise (201)Tl gated SPECT. Automated LV function analysis software was used for calculation of the postexercise and the rest LVEF. The best threshold between 0- to 1-vessel CAD and 2- to 3-vessel CAD was determined as the cutoff that on receiver-operating-characteristic analysis resulted in the best sensitivity for detection of multivessel CAD with an associated specificity of >90%. RESULTS: Only 18 (26.9%) of 67 patients with multivessel CAD had reversible defects in multiple territories. Sensitivities of the postexercise and the rest LVEF and the worsening of the LVEF by exercise did not differ from those of perfusion data alone. Sensitivities of the combination of perfusion data and the postexercise and rest LVEF did not differ from those of perfusion data alone, whereas the sensitivity of the combination of perfusion data and worsening of the LVEF (i.e., reversible defects in multiple territories or worsening of the LVEF >5.6% [or both]) was significantly greater than that of perfusion data alone (43.3% vs. 26.9%; P < 0.05), with an acceptable level of specificity (90.4%). CONCLUSION: The worsening of the LVEF by exercise has the potential to detect patients with multivessel CAD among those without multivessel patterns of reversible defects.