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.     

Left ventricular volumes and ejection fraction calculated from quantitative electrocardiographic-gated 99mTc-tetrofosmin myocardial SPECT.

We compared the left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) as calculated by Cedars automated quantitative gated SPECT (QGS) to those determined by first-pass radionuclide angiography (FPRNA) and contrast left ventriculography (LVG) in a group of 21 patients (mean age 61.4 +/- 9.2 y). METHODS: A total of 740 MBq 99mTc-tetrofosmin was administered rapidly into the right cubital vein at rest, and FPRNA was performed using a multicrystal gamma camera. One hour after injection, QGS was performed with a temporal resolution of 10 frames per R-R interval. LVG was performed within 2 wk. RESULTS: The EDV, ESV and LVEF calculated by QGS were highly reproducible (intraobserver, r = 0.99, r = 0.99 and r = 0.99, respectively; interobserver, r = 0.99, r = 0.99 and r = 0.99, respectively; P < 0.01) and were more consistent than those determined by FPRNA (intraobserver, r = 0.97, r = 0.95 and r = 0.93, respectively; interobserver, r = 0.86, r = 0.96 and r = 0.91, respectively; P < 0.01). There was a good correlation between EDV, ESV and LVEF by FPRNA and those by LVG (r = 0.61, r = 0.72 and r = 0.91, respectively; P < 0.01), and there was an excellent correlation between QGS and LVG (r = 0.73, r = 0.83 and r = 0.87, respectively; P < 0.01). The mean EDV by QGS (100 +/- 11.3 mL) was significantly lower than by FPRNA (132 +/- 16.8 mL) or LVG (130 +/- 8.1 mL), and the mean ESV by QGS (53.8 +/- 9.3 mL) was lower than by FPRNA (73.0 +/- 13.3 mL). Ejection fraction values were highest by LVG (57.1% +/- 3.2%), then QGS (51.8% +/- 3.0%) and FPRNA (48.9% +/- 2.4%). CONCLUSION: QGS gave more reproducible results than FPRNA. LV volumes and LVEF calculated by QGS correlated well to those by LVG.     

Assessment of left ventricular function by thallium-201 quantitative gated cardiac SPECT

PURPOSE: Present study was designed to evaluate the accuracy of the measurement of left ventricular volume by quantitative gated SPECT (QGS) software using 201T1 and the effect of cutoff frequency of Butterworth prereconstruction filter on the calculation of volume. METHODS: The RH-2 type cardiac phantom and 20 patients with ischemic heart disease were studied. Left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were calculated by the QGS software using the various frequency of Butterworth filter. These parameters were evaluated by Simpson's method using left ventriculography (LVG). RESULTS: The volume of the phantom calculated by QGS was under-estimated by 14%. In the clinical study, EDV and ESV measured by QGS were smaller than those obtained from LVG by 10%. When the cutoff frequency of Butterworth filter was 0.43 cycles/cm, the values measured by QGS were best correlated with those by LVG (EDV: r = 0.80, p < 0.001; ESV: r = 0.86, p < 0.001; EF: r = 0.80, p < 0.001). CONCLUSION: These data suggest that 201Tl quantitative gated cardiac SPECT can estimate myocardial ischemia and left ventricular function simultaneously.     

Improved accuracy in estimation of left ventricular function parameters from QGS software with Tc-99m tetrofosmin gated-SPECT: a multivariate analysis

The purpose of this study was to verify whether the accuracy of left ventricular parameters related to left ventricular function from gated-SPECT improved or not, using multivariate analysis. METHODS: Ninety-six patients with cardiovascular diseases were studied. Gated-SPECT with the QGS software and left ventriculography (LVG) were performed to obtain left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Then, multivariate analyses were performed to determine empirical formulas for predicting these parameters. The calculated values of left ventricular parameters were compared with those obtained directly from the QGS software and LVG. RESULTS: Multivariate analyses were able to improve accuracy in estimation of LVEF, EDV and ESV. Statistically significant improvement was seen in LVEF (from r = 0.6965 to r = 0.8093, p < 0.05). Although not statistically significant, improvements in correlation coefficients were seen in EDV (from r = 0.7199 to r = 0.7595, p = 0.2750) and ESV (from r = 0.5694 to r = 0.5871, p = 0.4281). CONCLUSION: The empirical equations with multivariate analysis improved the accuracy in estimating LVEF from gated-SPECT with the QGS software.     

Improved accuracy in estimation of left ventricular function parameters from QGS software with Tc-99m tetrofosmin gated-SPECT: a multivariate analysis

The purpose of this study was to verify whether the accuracy of left ventricular parameters related to left ventricular function from gated-SPECT improved or not, using multivariate analysis.Methods: Ninety-six patients with cardiovascular diseases were studied. Gated-SPECT with the QGS software and left ventriculography (LVG) were performed to obtain left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Then, multivariate analyses were performed to determine empirical formulas for predicting these parameters. The calculated values of left ventricular parameters were compared with those obtained directly from the QGS software and LVG.Results: Multivariate analyses were able to improve accuracy in estimation of LVEF, EDV and ESV. Statistically significant improvement was seen in LVEF (from r=0.6965 to r=0.8093, p<0.05). Although not statistically significant, improvements in correlation coefficients were seen in EDV (from r=0.7199 to r=0.7595, p=0.2750) and ESV (from r=0.5694 to r=0.5871, p=0.4281).Conclusion: The empirical equations with multivariate analysis improved the accuracy in estimating LVEF from gated-SPECT with the QGS software.     

Performance of OSEM and depth-dependent resolution recovery algorithms for the evaluation of global left ventricular function in 201Tl gated myocardial perfusion SPECT.

It is unknown whether the use of ordered-subsets expectation maximization (OSEM) and depth-dependent resolution recovery (RR) will increase the accuracy of (201)Tl electrocardiogram-gated SPECT (GSPECT) for the measurement of global left ventricular (LV) function. METHODS: Fifty-six patients having both rest (201)Tl GSPECT and planar equilibrium radionuclide angiography (planar(RNA)) on the same day were studied. Twenty-nine patients also had LV conventional contrast angiography (Rx). LV ejection fraction (LVEF), end-diastolic volume (EDV), and end-systolic volume (ESV) were calculated with the quantitative gated SPECT software (QGS) using 4 different processing methods: filtered backprojection (FBP), OSEM, RR + FBP, and RR + OSEM. LVEF calculated with planar(RNA) and LV EDV and ESV calculated with Rx were considered gold standards. LVEF and volumes provided with the GSPECT methods were compared with the gold standard methods. RESULTS: LVEF calculated with GSPECT methods (FBP, OSEM, RR + FBP, and RR + OSEM) were similar (not statistically significant) and correlated well with planar(RNA). On Bland-Altman analysis, the mean +/- SD of absolute difference in LVEF with GSPECT FBP, OSEM, RR + FBP, and RR + OSEM methods versus planar(RNA) were similar, with relatively large limits of agreement. LV volumes calculated with the 4 GSPECT methods were significantly lower but correlated well with Rx LV volumes. LV volumes calculated with FBP and OSEM were lower than those calculated with RR + FBP and RR + OSEM (P < 0.01). On Bland-Altman analysis, the mean +/- SD of absolute difference in LV volumes with FBP, OSEM, RR + FBP, and RR + OSEM versus Rx was, respectively, 56 +/- 45 mL (P < 0.01 vs. the other 3 methods), 57 +/- 45 mL (P < 0.01 vs. the other 3 methods), 43 +/- 48 mL, and 46 +/- 47 mL, with correspondingly large limits of agreement. The variance of random error did not differ between FBP, OSEM, RR + FBP, and RR + OSEM for either LVEF or volumes. CONCLUSION: OSEM and FBP presented similar accuracy for LVEF and volume measured with the QGS software. Their combination with depth-dependent RR provided similar LVEF but more accurate LV volumes.     

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.     

A newly developed maneuver,field change conversion (FCC), improved evaluation of the left ventricular volume more accurately on quantitative gated SPECT (QGS) analysis

PURPOSE: To investigate whether a newly developed maneuver that reduces the reconstruction area by a half more accurately evaluates left ventricular (LV) volume on quantitative gated SPECT (QGS) analysis. METHODS: The subjects were 38 patients who underwent left ventricular angiography (LVG) followed by G-SPECT within 2 weeks. Acquisition was performed with a general purpose collimator and a 64 x 64 matrix. On QGS analysis, the field magnification was 34 cm in original image (Original: ORI), and furthermore it was changed from 34 cm to 17 cm to enlarge the re-constructed image (Field Change Conversion: FCC). End-diastolic volume (EDV) and end-systolic volume (ESV) of the left ventricle were also obtained using LVG. RESULTS: EDV was 71 +/- 19 ml, 83 +/- 20 ml and 98 +/- 23 ml for ORI, FCC and LVG, respectively (p < 0.001: ORI versus LVG, p < 0.001: ORI versus FCC, p < 0.001: FCC versus LVG). ESV was 28 +/- 12 ml, 34 +/- 13 ml and 41 +/- 14 ml for ORI, FCC and LVG, respectively (p < 0.001: ORI versus LVG, p < 0.001: ORI versus FCC, p < 0.001: FCC versus LVG). CONCLUSION: FCC was better than ORI for calculating LV volume in clinical cases. Furthermore, FCC is a useful method for accurately measuring the LV volume on QGS analysis.     

Comparison of two software in gated myocardial perfusion single photon emission tomography, for the measurement of left ventricular volumes and ejection fraction, in patients with and without perfusion defects

Emory cardiac toolbox (ECTb) and quantitative gated single photon emission tomography - SPET (QGS) software are the two most often used techniques for automatic calculation of left ventricular volumes (LVV) and ejection fraction (LVEF). Few studies have shown that these software are not interchangeable, however the effect of perfusion defects on performance of these software has not been widely studied. The aim of this study was to compare the performance of QGS and ECTb for the calculation of LVEF, end-systolic volume (ESV) and end-diastolic volume (EDV) in patients with normal and abnormal myocardial perfusion. One hundred and forty-four consecutive patients with suspected coronary artery disease underwent a two-day protocol with dipyridamole stress/rest gated technetium-99m-methoxy isobutyl isonitrile ((99m)Tc-sestamibi) myocardial perfusion (GSPET) (8 gates/cardiac cycles). Rest GSPET scintiscan findings were analyzed using QGS and ECTb. Correlation between the results of QGS and ECTb was greater than 90%. In patients with no perfusion defects, EDV and LVEF using ECTb, were significantly higher than using QGS (P<0.001), whereas no significant difference was noticed in ESV (P=0.741). In patients with perfusion defects, also ECTb yielded significantly higher values for EDV, ESV and LVEF than QGS (P<0.001). In tomograms of patients with perfusion defects, mean differences of EDV and ESV between the two software, were significantly higher than in tomograms of patients without defects (P<0.001), while for LVEF this difference was not significant (P= 0.093). Patients were classified into three subgroups based on the summed rest score (SRS); G1: patients with SRS < or = 3 (n=109), G2: patients with 4 < or = SRS < or = 8 (n=13) and G3: patients with SRS > or = 9 (n=22). One-way ANOVA showed that the mean differences of EDV and ESV values between ECTb and QGS between the subgroups were significant (P<0.001 for both parameters), while no significant difference was noticed between the subgroups, as for the mean difference of LVEF, calculated by the two software (P=0.07). By increasing SRS, the EDV and ESV values were overestimated to a higher level by the ECTb as compared to the QGS software. Linear regression analysis showed that the difference in LVV values, between the two software increased, when SRS also increased (P<0.001). In conclusion, correlation between QGS and ECTb, software was very good both in patients with and without perfusion defects. In patients with perfusion defects, calculated LVEF, ESV and EDV values are higher using ECTb compared to the QGS software. However, the more extensive the perfusion defect was, the greater the difference of LVV between these two software. For the follow up of patients, we suggest the use of a single software either QGS or ECTb, for serial measurements of LV function.     

Normal limits for left ventricular ejection fraction and volumes estimated with gated myocardial perfusion imaging in patients with normal exercise test results: Influence of tracer, gender, and acquisition camera

BACKGROUND: Myocardial imaging with tracers such as technetium-99m sestamibi or thallium-201 is extensively used as a means of measuring myocardial perfusion. With gated acquisition, these tracers can also be used as a means of measuring left ventricular ejection fraction (EF) and end diastolic and end systolic volumes (EDV and ESV, respectively). The objective of this study was to determine the normal range of EF, EDV, and ESV and to evaluate differences caused by either the tracer used, the gender of the patient, or the acquisition camera used. METHODS AND RESULTS: A total of 1513 consecutive patients (mean age, 60+/-12 years [SD]) who had normal results on Bruce exercise tests had either Tc-99m sestamibi (n = 884) or Tl-201 (n = 629) injected at peak stress. Although all patients were referred for the evaluation of chest pain or dyspnea and many had cardiac risk factors, all had normal exercise capacity corrected for age, no electrocardiographic signs of ischemia, normal results on perfusion scans, and normal wall motion determined by means of quantitated gated single photon emission computed tomography (QGS). Scans were acquired on 1 of 3 different cameras. The mean EF for all patients who had gated Tc-99m sestamibi scans was 63% +/- 9%, not different from patients who had gated Tl-201 scans (63% +/- 9%). However, when the gender of the patient was considered, the mean EF for women was 66% +/- 8% with Tc-99m sestamibi (n = 519), higher than the mean EF for men (58% +/- 8%, n = 365, P<.0001). Similarly, the mean EF for women studied with Tl-201 (67% +/- 8%, n = 326) was higher than that of men (59% +/- 7%, n = 303,P<.0001). Patients with diabetes mellitus (n = 153) had a slightly reduced EF (62% +/- 10%, P<.001). In a subset of 240 patients, 140 patients studied with Tc-99m sestamibi and 100 studied with Tl-201, the EDV and ESV for women (n = 124) was estimated by means of QGS to be lower (57 +/- 17 mL and 19 +/- 11 mL, respectively) than those for men (74 +/- 22 mL-and 29 +/- 13 mL, respectively; n = 116; P<.001 for each comparison). No clinically significant differences in EF or volumes were noted based on tracers used or acquisition camera. For patients with normal results on exercise treadmill tests and perfusion imaging, the lower limit of normal for EF with gated perfusion imaging with QGS was 50% for women and 43% for men. For EDV and ESV, the upper limit of normal was 91 mL and 40 mL, respectively, for women and 119 mL and 55 mL, respectively, for men. CONCLUSIONS: No significant differences related to either tracer or acquisition camera used were noted for EF, suggesting equivalency for clinical trials for patients with normal results on exercise tests. However, EF, EDV, and ESV determined by means of gated perfusion imaging need to be corrected for gender.     

Influence of left ventricular geometry on thallium-201 gated single-photon emission tomographic findings in patients with known or suspected coronary artery disease

Background

Recent studies have shown good correlations between echocardiography and Tl-201 gated single-photon emission computed tomography (SPECT) for the assessment of left ventricular volumes and ejection fraction. We assessed how left ventricular geometry affected correlations between these values measured by the 2 methods in patients with known or suspected coronary artery disease.

Methods and results

There were 109 patients with normal left ventricular geometry, 20 patients with concentric remodeling, 32 patients with eccentric hypertrophy and 28 patients with concentric hypertrophy. In all 4 groups, there were good correlations between end-diastolic volume (EDV) and end-systolic volume (ESV) values measured by echocardiography and quantitative gated SPECT (QGS). EDV and ESV values measured by QGS were significantly underestimated than those measured by echocardiography except for ESV in eccentric hypertrophy. In all 4 groups, ejection fraction (EF) value measured by echocardiography significantly correlated with that measured by QGS, but Bland–Altman plot showed a proportional error. EF value measured by QGS was likely to be overestimated when EF value increased from the median value, and to be underestimated when EF value decreased from the median value especially in concentric remodeling.

Conclusions

Tl-201 gated SPECT is a useful tool for the assessment of left ventricular volumes and function, but it requires methodological considerations according to left ventricular geometry.     

Measurement of left ventricular volumes and ejection fraction by quantitative gated SPET,contrast ventriculography and magnetic resonance imaging: a meta-analysis

All previous validation studies of quantitative gated single-photon emission tomography (QGS) have examined relatively few patients, and the accuracy of QGS thus remains uncertain. We performed a meta-analysis of data from 301 participants in ten studies that compared QGS using technetium-99m-labelled tracers with contrast left ventriculography (LVG), and from 112 participants in six studies that compared QGS with magnetic resonance imaging (MRI). Linear regression and Bland-Altman analyses were used to evaluate pooled data from individuals across the studies. The correlation between QGS and LVG for end-diastolic volume (EDV) (r=0.81, SEE=27 ml), end-systolic volume (ESV) (r=0.83, SEE=18 ml) and ejection fraction (EF) (r=0.79, SEE=8.3%) was good, as was that between QGS and MRI for EDV (r=0.87, SEE=34 ml), ESV (r=0.89, SEE=27 ml) and EF (r=0.88, SEE=7.2%). However, Bland-Altman plots indicated that LVG minus QGS differences for EDV generated a systematic and random error of 32+/-58 ml (mean+/-2SD), and that MRI minus QGS generated an error of 13+/-73 ml. In the subgroup of patients in whom ECG gating was set at eight intervals, QGS significantly underestimated EF by 7.6%+/-17.4% (mean+/-2SD) compared with LVG and by 6.3%+/-14.6% compared with MRI; no such underestimation was observed in the subgroup in whom ECG gating was set at 16 intervals. We conclude that in patients with ECG gating set at eight intervals, QGS systematically underestimates LV volumes and EF compared with both LVG and MRI. Since QGS also shows considerable variations around the systematic deviations, there remains uncertainty over whether an individual value determined with QGS approximates the true LV volumes and EF.     

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.     

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.     

Validation of QGS and 4D-MSPECT for quantification of left ventricular volumes and ejection fraction from gated 18F-FDG PET: comparison with cardiac MRI.

The aim of this study was to validate Quantitative Gated SPECT (QGS) and 4D-MSPECT for assessing left ventricular end-diastolic and systolic volumes (EDV and ESV, respectively) and left ventricular ejection fraction (LVEF) from gated (18)F-FDG PET. METHODS: Forty-four patients with severe coronary artery disease were examined with gated (18)F-FDG PET (8 gates per cardiac cycle). EDV, ESV, and LVEF were calculated from gated (18)F-FDG PET using QGS and 4D-MSPECT. Within 2 d (median), cardiovascular cine MRI (cMRI) (20 gates per cardiac cycle) was done as a reference. RESULTS: QGS failed to accurately detect myocardial borders in 1 patient; 4D-MSPECT, in 2 patients. For the remaining 42 patients, correlation between the results of gated (18)F-FDG PET and cMRI was high for EDV (R = 0.94 for QGS and 0.94 for 4D-MSPECT), ESV (R = 0.95 for QGS and 0.95 for 4D-MSPECT), and LVEF (R = 0.94 for QGS and 0.90 for 4D-MSPECT). QGS significantly (P < 0.0001) underestimated LVEF, whereas no other parameter differed significantly between gated (18)F-FDG PET and cMRI for either algorithm. CONCLUSION: Despite small systematic differences that, among other aspects, limit interchangeability, agreement between gated (18)F-FDG PET and cMRI is good across a wide range of clinically relevant volumes and LVEF values assessed by QGS and 4D-MSPECT.     

Left ventricular function parameters obtained from gated myocardial perfusion SPECT imaging: a comparison of two data processing systems

BACKGROUND AND AIM: The Cedars-Sinai Quantitative Gated Single Photon Emission Computed Tomography (SPECT) (QGS) program, used to quantify left ventricular function parameters from gated myocardial perfusion scintigraphy (MPS), has been extensively validated and compared with other methods of quantification. However, little is known about the reproducibility of QGS on different processing systems. This study compared the findings of QGS running on workstations provided by two different manufacturers. METHODS: Gated rest MPS studies of 50 patients were analysed retrospectively. Filtered back-projection (FBP) was performed using identical parameters on Philips Pegasys and Nuclear Diagnostics Hermes workstations to produce gated short-axis (SA) slices. In addition, the gated SA slices reconstructed on the Pegasys were transferred to the Hermes. QGS was used to calculate the end-diastolic volume (EDV), end-systolic volume (ESV) and left ventricular ejection fraction (LVEF) in each case. RESULTS: The mean+/-standard deviation differences between the Pegasys and Hermes function parameters were -7.06+/-3.91 ml (EDV), -5.54+/-3.21 ml (ESV) and +1.14%+/-1.43% (LVEF) when data were reconstructed on different systems, and -0.16+/-1.58 ml (EDV), -0.10+/-1.02 ml (ESV) and +0.14%+/-0.73% (LVEF) when data were reconstructed on the same system. Bland-Altman plots showed definite trends for EDV and ESV for data reconstructed on different systems, but no trends were seen for data reconstructed on the same system. CONCLUSIONS: When data were reconstructed on two separate systems, the difference between the function parameters obtained from Pegasys and Hermes could be ascribed to differences in the reconstruction process on each system despite the use of identical parameters (filters, etc). However, when the same reconstructed data were analysed on both systems, no significant difference in left ventricular function parameters was observed.     

Left ventricular volumes, ejection fraction, and regional wall motion calculated with gated technetium-99m tetrofosmin SPECT in reperfused acute myocardial infarction at super-acute phase: Comparison with left ventriculography

BACKGROUND: Noninvasive assessment of acute myocardial infarction (AMI) requires information about both myocardial perfusion and left ventricular (LV) function. The automated quantification of electrocardiographic-gated myocardial scintigraphy with technetium-99m tetrofosmin (QGS) can provide this information. METHODS AND RESULTS: Coronary arteriography, QGS, and left ventriculography (LVG) were performed in 229 patients with reperfused AMI within 2 days after onset. All infarcted vascular territories (229 segments) were visualized with scintigraphic perfusion images. The mean wall motion score (WMS) was 15.9+/-2.8 by means of QGS and 16.3+/-2.9 by means of LVG. The correlation between WMS obtained by means of QGS and that obtained by means of LVG was close (y = 0.913x + 1.016, r = 0.94, P<.001), but that obtained by means of QGS was significantly lower than that obtained by means of LVG (P<.0001). Total agreement for the assessment of regional wall motion reached 75 % (kappa, 0.66). Although the LV values obtained by means of QGS and LVG correlated well (end-diastolic volume, r = 0.67, P<.0001; end-systolic volume, r = 0.79, P<.0001; ejection fraction, r = 0.78, P<.0001), end-diastolic volume and ejection fraction tended to be underestimated with QGS. CONCLUSION: QGS data were considered to be useful in detecting infarcted vascular territory and LV function, even in AMI, within 2 days after onset.     

The impacts of severe perfusion defects,akinetic/dyskinetic segments,and viable myocardium on the accuracy of volumes and LVEF measured by gated 99mTc-MIBI SPECT and gated 18F-FDG PET in patients with left ventricular aneurysm: cardiac magnetic resonance imaging as the reference

Background

To compare the accuracy of end-diastolic and end-systolic volumes (EDV, ESV) and LV ejection fraction (LVEF) measured by both GSPECT and GPET, using cardiac magnetic resonance imaging (CMR) as a reference. Furthermore, the impacts of severe perfusion defects, akinetic/dyskinetic segments, and residual viable myocardium on the accuracy of LV functional parameters were investigated.

Methods

Ninety-six consecutive patients with LV aneurysm and LV dysfunction (LVEF 32 ± 9%) diagnosed by CMR were studied with GSPECT and GPET. EDV, ESV, and LVEF were calculated using QGS software.

Results

Correlations of volumes were excellent (r 0.81-0.86) and correlation of LVEF was moderate (r 0.65-0.76) between GSPECT vs CMR and between GPET vs CMR. Compared with CMR, ESV was overestimated by GSPECT (P < .01) and underestimated by GPET (P < .0001); EDV was underestimated by GPET (P < .001); LVEF was underestimated by GSPECT but overestimated by GPET (both P < .001). Multivariate regression analysis revealed that the number of segments with severe perfusion defects (P < .001) was the only independent factor which was correlated to the EDV difference between GSPECT and CMR, the number of akinetic/dyskinetic segments with absent wall thickening (WT) was the only independent factor which was significantly correlated to the differences of ESV and LVEF measurements between GSPECT vs CMR and between GPET vs CMR (P < .0001), respectively. Neither the mismatch score nor the segments with viable myocardium were correlated to the differences of LV volumes and LVEF measurements between different imaging modalities.

Conclusions

In LV aneurysm patients, LV volumes and LVEF measured by both GSPECT and GPET imaging correlated well with those determined by CMR, but should not be interchangeable in individual patients. The accuracy of LVEF measured by GSPECT and GPET was affected by the akinetic/dyskinetic segments with absent WT.     

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.     

Evaluation of cardiac resynchronization therapy in drug-resistant dilated-phase hypertrophic cardiomyopathy by means of Tc-99m sestamibi ECG-gated SPECT

This case describes a 65-year-old male with drug-resistant heart failure. Cardiac resynchronization therapy was performed. We evaluated cardiac function with volume curve differentiation software (VCDiff) from QGS data with Tc-99m sestamibi. Left ventricular parameters during atrial-right ventricular pacing were left ventricular ejection fraction (LVEF) 30%, end-diastolic volume (EDV) 156 ml, end-systolic volume (ESV) 108 ml and peak filling rate 1.12 (EDV/sec). And during dual chamber pacing, those were LVEF 35%, EDV 145 ml and ESV 95 ml and PFR 1.58 (EDV/sec). And during atrial-left ventricular pacing, those were LVEF 36%, EDV 152 ml, ESV 97 ml and peak filling rate (PFR) 1.35 (EDV/sec). Cardiac resynchronization therapy may improve cardiac function as well as dyssynchrony, which could be evaluated non-invasively and accurately by ECG-gated SPECT.