Comparison of 99mTc tetrofosmin gated SPECT measurements of left ventricular volumes and ejection fraction with MRI over a wide range of values

Comparison of Left Ventricular Volumes Measured by 3DE, SPECT and CMR

BACKGROUND

Information regarding left ventricular (LV) volume and left ventricular ejection fraction (LVEF) has major diagnostic and prognostic value when assessing patients after ST-elevation myocardial infarction (STEMI). We aimed to investigate the agreement between measurement of LV volumes and LVEF by three-dimensional echocardiography (3DE), single-photon emission computed tomography (SPECT) and cardiac magnetic resonance (CMR) imaging in patients in a stable phase after STEMI.

METHODS

Fifteen patients underwent examinations by 3DE, SPECT and CMR three months after STEMI.

RESULTS

There was a significant bias in end-diastolic volume (EDV) measured by 3DE (–64 mL, p < 0.001) and SPECT (–55 mL, p < 0.001) compared with that measured by CMR. This was also the case for end-systolic volume (ESV) measured by 3DE (–36 mL, p < 0.001) and SPECT (–28 mL, p < 0.001). No significant differences were found between 3DE and SPECT for EDV or ESV. However, LVEF did not differ between the three methods. The agreement between all three methods was moderate (intra-class correlation coefficient [ICC] = 0.44) for LV volume and good for LVEF (ICC = 0.72).

CONCLUSIONS

LV volumes assessed by 3DE did not differ from SPECT, and despite larger LV volumes by CMR, measurements of LVEF showed good agreement between all three methods.

Gated SPECT in assessment of regional and global left ventricular function: an update

Gated myocardial perfusion SPECT (GSPECT) is a major clinical tool, widely used for performing myocardial perfusion imaging procedures. In this review, we have presented the fundamentals of GSPECT and the ways in which the functional measurements it provides have contributed to the emergence of myocardial perfusion SPECT in its important role as a major tool of modern cardiac imaging. GSPECT imaging has shown unique capability to provide accurate, reproducible and operator-independent quantitative data regarding myocardial perfusion, global and regional systolic and diastolic function, stress-induced regional wall-motion abnormalities, ancillary markers of severe and extensive disease, left ventricular geometry and mass, as well as the presence and extent of myocardial scar and viability. Adding functional data to perfusion provides an effective means of increasing both diagnostic accuracy and reader's confidence in the interpretation of the results of perfusion scans. Assessment of global and regional LV function has improved the prognostic power of myocardial perfusion SPECT and has been shown in a large registry to add to the perfusion assessment in predicting benefit from revascularization.

Comparison of (99m)Tc-MIBI SPECT/18F-FDG PET imaging and cardiac magnetic resonance imaging in patients with idiopathic dilated cardiomyopathy: assessment of cardiac function and myocardial injury

OBJECTIVE

The aim of this study is to evaluate the agreement between myocardial F-FDG PET imaging and cardiac magnetic resonance imaging (cMRI) in assessing cardiac function and relationship of cMRI late gadolinium enhancement (cMRI-LGE) and myocardial perfusion/metabolism pattern in patients with idiopathic dilated cardiomyopathy (IDCM).

METHODS

Forty-two consecutive patients diagnosed with IDCM were enrolled. All patients underwent Tc-MIBI SPECT, gated F-FDG PET imaging, and cMRI within 3-7 days. Cardiac function parameters were calculated using PET and cMRI. The segments analysis was performed using a 17-segment model. Patterns of perfusion/metabolism were classified as normal, mismatch, mild-to-moderate match, and severe match, and cMRI-LGE was classified into 3 categories (non-LGE, mid-wall LGE, and transmural LGE).

RESULTS

The correlation between gated PET and cMRI was excellent for end-diastolic volume (EDV; r = 0.948, P < 0.001), end-systolic volume (ESV; r = 0.939, P < 0.001), and left ventricular ejection fraction (LVEF; r = 0.685, P < 0.001). EDV and ESV were underestimated, whereas LVEF was slightly overestimated by gated PET in comparison to cMRI. Perfusion/metabolism patterns varied in 3 different categories of non-LGE, mid-wall LGE, and transmural LGE (χ = 14.276, P < 0.001). Also, 71.0% (44/62) segments with mid-wall LGE had normal perfusion/metabolism patterns, and 75.9% (63/83) perfusion/metabolism mismatch segments were shown as non-LGE. The incidence of LGE was significantly higher in segments with severe match than the other 3 segment groups (χ = 112.53, P < 0.001).

CONCLUSION

There is an excellent agreement between gated PET and cMRI in assessment of cardiac function. LGE-cMRI is much more sensitive in detecting moderate fibrosis, while PET could detect more impaired but viable myocardium. Combining the 2 imaging modalities is useful for providing more comprehensive evaluations of myocardial injury in patients with IDCM.

Assessment of left ventricular volume and ejection fraction: comparison of QGS and MBGS analyses of ECG-gated myocardial perfusion SPECT imaging

OBJECTIVES

The purpose of this study was to compare quantitative ECG-gated single-photon emission computed tomography (SPECT) (QGS) and model-based ECG-gated single-photon emission computed tomography (MBGS) for determination of end-diastolic cardiac volume (EDV), end-systolic cardiac volume (ESV), and left ventricular ejection fraction (LVEF). The accuracy of both methods was evaluated by measurements obtained from contrast left ventriculography (LVG).

METHODS

Forty-five patients (40 male, age: 55+/-11 years) with coronary artery disease were studied by angiography and ECG-gated SPECT using technetium-99m-sestamibi for the evaluation of myocardial perfusion and LVEF. Short axis SPECT images were analyzed by QGS and MBGS to estimate endocardial and epicardial surfaces and to derive EDV, ESV, and LVEF.

RESULTS

EDV by gated SPECT (QGS: 187+/-71 ml; MBGS: 191+/-76 ml) were lower than corresponding values by LVG (203+/-59 ml), whereas ESV by gated SPECT (QGS: 121+/-62 ml; MBGS: 108+/-54 ml) were higher than by LVG (105+/-49 ml). Thus, LVEFs by gated SPECT (QGS: 39+/-12%; MBGS: 45+/-9%) were significantly lower than by LVG (50+/-15%). LVEF by MBGS was significantly higher than by QGS (P<0.05). A significant correlation was observed among QGS, MBGS, and LVG for the calculation of EDV, ESV, and LVEF.

CONCLUSION

Measurements of LV volumes and LVEF by QGS and MBGS showed close agreement with each other and with results from LVG. However, both methods measure lower values for EDV and higher values for ESV and thus underestimate LVEF compared with LVG.

Comparison of the reproducibility of quantitative cardiac left ventricular assessments in healthy volunteers using different MRI scanners: a multicenter simulation

PURPOSE

To derive reproducibility assessments of ejection fraction (EF) and left ventricular mass (LVM) from short-axis cardiac MR images acquired at single and multiple time-points on different 1.5T scanner models.

MATERIALS AND METHODS

Images of 15 healthy volunteers were acquired twice using a Magnetom Avanto scanner (Siemens, Erlangen, Germany) and once using a Signa Excite scanner (General Electric, Milwaukee, WI, USA) over four months, and analyzed using ARGUS and MASS Analysis+ software, respectively. Two physicists independently segmented the myocardial borders in order to derive intra- and interobserver assessments of EF and LVM for single and multiple time-points on the same and different scanners.

RESULTS

For EF, the coefficient of repeatability (CoR) increased as different observers, multiple time-points, and different scanners were introduced. The CoR ranged from 2.8% (intraobserver measurements, single time-point, same scanner) to 10.0% (interobserver measurements, different time-points, different scanners). For LVM, intraobserver CoR parameters were consistently smaller than interobserver values. The CoR ranged from 7.8 g (intraobserver measurements, single time-point, same scanner) to 39.5 g (interobserver measurements, different time-points, different scanners).

CONCLUSION

Reproducible EF data can be obtained at single or multiple time-points using different scanners. However, LVM is notably susceptible to interobserver variation, and this should be carefully considered if similar evaluations are planned as part of multicenter or longitudinal investigations.

Comparison of gated SPECT, echocardiography and cardiac magnetic resonance imaging for the assessment of left ventricular ejection fraction and volumes

BACKGROUND

Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV) can be determined non-invasively by two-dimensional enchocardiography (ECHO), gated sinle photon emission computed tomography (GSPECT) and cardiac magnetic resonance imaging (CMRI). This study was designed to analyze the concordance between LVEF, EDV and ESV values derived from ECHO, GSPECT and CMRI.

METHODS

ECHO, GSPECT and CMRI were performed in a group of 21 patients with suspected coronary artery disease. LVEF, EDV and ESV values were calculated.

RESULTS

The mean LVEF measured with GSPECT, ECHO and CMRI were 55.9+/-17.8%, 55.7+/-16.4% and 56.4+/-15.7%, respectively. The mean EDV measured with GSPECT, ECHO and CMRI were 109.2+/-42.45 mL, 127.5+/-42.2 mL, 91.1+/-38.0 mL, respectively. The mean ESV measured with GSPECT, ECHO and CMRI were 54.2+/-41.2 mL, 59.9+/-37.6 mL and 41.8+/-26.9 mL, respectively. The results of linear regression analysis showed very good correlation between LVEF and ESV values derived from GSPECT, ECHO adn CMRI (r=0.91, r=0.92, r=0.97 for LVEF and r=0.86, r=0-91, r=0.91 for ESV, P<0.01). Good correlations were found between EDV values obtained from GSPECT, ECHO and CMRI (r=0.71, r=0.68, r=0.73, P<0.01). Agreement between these techniques in LVEF values was also good, but not in LV volumes, according to Bland-Altman plots.

CONCLUSIONS

This study showed good overall correlations between LVEF, EDV and ESV values derived from GSPECT, ECHO and CMRI. LVEF obtained from any of these three imaging modalities could be used interchangeably. However, care should be taken in comparing LV volumes.

Quantitation in gated perfusion SPECT imaging: the Cedars-Sinai approach

Cedars-Sinai's approach to the automation of gated perfusion single photon emission computed tomography (SPECT) imaging is based on the identification of key procedural steps (processing, quantitation, reporting), each of which is then implemented, in completely automated fashion, by use of mathematic algorithms and logical rules combined into expert systems. Our current suite of software applications has been designed to be platform- and operating system-independent, and every algorithm is based on the same 3-dimensional sampling scheme for the myocardium. The widespread acceptance of quantitative software by the nuclear cardiology community (QGS alone is used at over 20,000 locations) has provided the opportunity for extensive validation of quantitative measurements of myocardial perfusion and function, in our opinion, helping to make nuclear cardiology the most accurate and reproducible modality available for the assessment of the human heart.

The expanding role of left ventricular functional assessment using gated myocardial perfusion SPECT: the supporting actor is stealing the scene

BACKGROUND

Gating of single-photon emission computed tomography (SPECT) has significantly improved the reliability and diagnostic accuracy of myocardial perfusion imaging. The functional parameters derived from this technique, mainly left ventricular volumes and ejection fraction, have been demonstrated to be accurate and reproducible. They are able to increase the detection of severe and extensive coronary artery disease and show a significant incremental prognostic power over perfusion abnormalities. Therefore, the importance given to gated SPECT functional data has progressively grown.

DISCUSSION

This circumstance has further expanded the indications for myocardial perfusion imaging and strengthened its position among the different imaging modalities. Moreover, several studies show that the evaluation of ventricular function may have a leading part in justifying the execution of perfusion scintigraphy in various clinical conditions.

AIM

Aim of this review is to describe this evolution of gated SPECT functional assessment from a supporting rank with respect to perfusion, to a main actor position in the field of cardiac imaging.

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: validation of an elastic surface model approach in comparison to cardiac magnetic resonance imaging, 4D-MSPECT and QGS

PURPOSE

The segmentation algorithm ESM based on an elastic surface model was validated for the assessment of left ventricular volumes and ejection fraction from ECG-gated myocardial perfusion SPECT. Additionally, it was compared with the commercially available quantification packages 4D-MSPECT and QGS. Cardiac MRI was used as the reference method.

METHODS

SPECT and MRI were performed on 70 consecutive patients with suspected or proven coronary artery disease. End-diastolic (EDV) and end-systolic (ESV) volumes and left ventricular ejection fraction (LVEF) were derived from SPECT studies by using the segmentation algorithms ESM, 4D-MSPECT and QGS and from cardiac MRI.

RESULTS

ESM-derived values for EDV and ESV correlated well with those from cardiac MRI (correlation coefficients R=0.90 and R=0.95, respectively), as did the measurements for LVEF (R=0.86). Both EDV and ESV were slightly overestimated for larger ventricles but not for smaller ventricles; LVEF was slightly overestimated irrespective of ventricle size. The above correlation coefficients are comparable to those for the 4D-MSPECT and QGS segmentation algorithms. However, results obtained with the three segmentation algorithms are not interchangeable.

CONCLUSION

The ESM algorithm can be used to assess EDV, ESV and LVEF from gated perfusion SPECT images. Overall, the performance was similar to that of 4D-MSPECT and QGS when compared with cardiac MRI. Results obtained with the three tested segmentation methods are not interchangeable, so that the same algorithm should be used for follow-up studies and control subjects.

Evaluation of right and left ventricular function by quantitative blood-pool SPECT (QBS): Comparison with conventional methods and quantitative gated SPECT (QGS)

Though quantitative ECG-gated blood-pool SPECT (QBS) has become a popular tool in research settings, more verification is necessary for its utilization in clinical medicine. To evaluate the reliability of the measurements of left and right ventricular functions with QBS, we performed QBS, as well as first-pass pool (FPP) and ECG-gated blood-pool (GBP) studies on planar images in 41 patients and 8 healthy volunteers. Quantitative ECG-gated myocardial perfusion SPECT (QGS) was also performed in 30 of 49 subjects. First, we assessed the reproducibility of the measurements of left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume (LVEDV, RVEDV) with QBS. Second, LVEF and RVEF obtained from QBS were compared with those from FPP and GBP, respectively. Third, LVEF and LVEDV obtained from QBS were compared with those from QGS, respectively. The intra- and inter-observer reproducibilities were excellent for LVEF, LVEDV, RVEF and RVEDV measured with QBS (r = 0.88 to 0.96, p < 0.01), while the biases in the measurements of RVEF and RVEDV were relatively large. LVEF obtained from QBS correlated significantly with those from FPP and GBP, while RVEF from QBS did not. LVEF and LVEDV obtained from QBS were significantly correlated with those from QGS, but the regression lines were not close to the lines of identity. In conclusion, the measurements of LVEF and LVEDV with QBS have good reproducibility and are useful clinically, while those of RVEF and RVEDV are less useful compared with LVEF and LVEDV. The algorithm of QBS for the measurements of RVEF and RVEDV remains to be improved.

Validation of a new automated method for analysis of gated-SPECT images

We recently presented a new method for quantification of CArdiac FUnction--denoted CAFU--as the first step in the development of an automated method for integrated interpretation of gated myocardial perfusion single photon emission computed tomography (SPECT) images. The aim of this study was to validate CAFU in the assessment of global and regional function of the left ventricle. Quantitative gated-SPECT (QGS), the most widely used software package for quantification of gated-SPECT images, was used as reference method for the measurements of ejection fraction (EF) and ventricular volumes, and visual analysis by an experienced physician was used as reference method for the measurements of regional wall motion and thickening. Two different groups of consecutive patients referred for myocardial perfusion scintigraphy were studied. Global function was evaluated in 316 patients and regional function in 49 other patients. The studies were performed using a 2-day stress/rest 99 m-Tc-sestamibi protocol. A good correlation was found between EF values from QGS and CAFU (EF CAFU = 0.84 EF QGS + 13, r = 0.94), but CAFU values were on average 4 EF points higher than QGS values. With CAFU the segments with normal thickening according to the physician showed significantly higher thickening values (in all parts of the myocardium) compared to the segments classified as having abnormal thickening. In conclusion, this study demonstrates that CAFU can be used to quantify global and regional function in gated-SPECT images. This is an important step in our development of an automated method for integrated interpretation of gated-SPECT myocardial perfusion scintigraphy studies.

Development of quantification software using model-based segmentation of left ventricular myocardium in gated myocardial SPECT

Gated myocardial single photon emission computed tomography (SPECT) is being used for the diagnosis of coronary artery diseases. In this study, we developed new software for the quantification of volumes and ejection fraction (EF) on the gated myocardial SPECT data using a cylindrical model. Volumes and EF by developed software were validated by comparing with those quantified by quantitative gated SPECT (QGS) software. Cylinder model for left ventricular myocardium was used to eliminate background activity and count profiles across the myocardium were fitted to the Gaussian curve to determine the endocardial and epicardial boundary. End-diastolic volume (EDV), end-systolic volume (ESV) and EF were calculated using this boundary information. Gated myocardial SPECT was performed in 83 patients. EDV, ESV and EF values estimated using present method were compared to those obtained using the commercialized software QGS, and reproducibility in the parameter estimation was assessed. EF, EDV and ESV obtained using two methods were correlated well (correlation coefficients = 0.96, 0.96 and 0.98). The correlation between the parameters repetitively estimated from the same data set by an operator was very high (correlation coefficients = 0.96, 0.99 and 0.99 for EF, EDV and ESV). On the repeated acquisition, reproducibility was also high with correlation coefficients of 0.89, 0.97 and 0.98. The present software will be useful for the development of new parameters for describing the perfusion and function of the LV.

Evaluation of left ventricular ejection fraction by the quantitative algorithms QGS, ECTb, LMC and LVGTF using gated myocardial perfusion SPECT: investigation of relative accuracy

AIM

To compare the quantitative algorithms Emory Cardiac Toolbox (ECTb), quantitative gated SPECT (QGS), layer of maximum counts (LMC), and left ventricular global thickening fraction (LVGTF) using gated myocardial tomography in the calculation of the left ventricular ejection fraction using the regression without truth (RWT) technique.

MATERIALS AND METHODS

Seventy-four consecutive patients were included in the study (59 males). All patients underwent stress-rest myocardial perfusion SPECT using Tc-tetrofosmin. Analysis of variance (ANOVA), the paired Student's t-test, the Pearson correlation coefficient and Bland-Altman were used for comparing the methods. The relative accuracy was performed by RWT.

RESULTS

ANOVA revealed a significant difference among the methods in calculating the ejection fraction. RWT showed that ECTb and QGS outperformed the other two methods. The ECTb was slightly better than QGS, and LMC was slightly better than LVGTF. QGS and ECTb achieved good correlations in end diastolic volume, end systolic volume and ejection fraction measurements. One-way ANOVA demonstrated that QGS was the only software program affected by the category of the perfusion summed stress score (SSS), P=0.038. The ejection fraction determined by the QGS, ECTb and LVGTF methods correlated significantly with defect size (r=0.545, P<0.0001; r=0.530, P<0.0001; and r=0.419, P<0.0001, respectively), but the LMC method was not significantly correlated (r=0.216, P=0.067).

CONCLUSIONS

There was a considerable variation among the quantitative gated SPECT methods in the evaluation of the ejection fraction. RWT revealed that the ECTb and QGS outperformed the other two methods with respect to the bias and precision of the measurements. Pair-wise correlations of the four methods ranged from mild to good with large agreement limits. Results of RWT provided important information in ranking the quantitative gated SPECT methods.

Contrast Echocardiography Versus Gated Single Photon Emission Computed Tomography for the Assessment of Parameters of Left Ventricular Remodeling After Acute Myocardial Infarction

BACKGROUND

Assessment of parameters of left ventricular (LV) remodeling after acute myocardial infarction (AMI) has both therapeutic and prognostic implication. Contrast echocardiography (CE) has the advantage of simultaneously assessing myocardial perfusion and LV remodeling. We aimed to evaluate the accuracy of CE to assess LV remodeling after AMI compared with technetium-99m sestamibi gated single photon emission computed tomography (SPECT).

METHODS

Accordingly, 36 consecutive patients underwent gated SPECT, CE, and cardiovascular magnetic resonance imaging (CMR) 7 to 10 days after AMI. LV ejection fraction (LVEF), and LV end-systolic and end-diastolic volumes were assessed.

RESULTS

Absolute differences for LVEF and LV end-diastolic volume between CMR and CE were significantly smaller than that between CMR and SPECT. CE estimate of LVEF more accurately classified patients into LVEF less than 35%, 35% to 45%, and greater than 45% (agreement = 83%, kappa = 0.66 with CMR) compared with SPECT (agreement = 61%, kappa = 0.36 with CMR).

CONCLUSION

CE is more accurate than gated SPECT for the estimation of LV remodeling after AMI.

Exercise- or dipyridamole-loaded QGS is useful to evaluate myocardial ischemia and viability in the patients with a history of Kawasaki disease

BACKGROUND

Evaluation of myocardial ischemia and viability is very important for the management of patients with a history of Kawasaki disease (KD). (99m)Tc-tetrofosmin myocardial perfusion scintigraphy combined with quantitative gated single photon computed emission tomography (QGS) gives us information, not only about perfusion, but also the percentage change in left ventricular wall thickness (%WT) and relative changes in left ventricular wall motion (LVM).

METHODS

The subjects were 27 patients with a history of KD followed as outpatients at the National Cardiovascular Center, Osaka, Japan. Exercise-loaded QGS was performed on 21 patients, and dipyridamole- loaded QGS was performed in six patients younger than 7 years old.

RESULTS

Perfusion defects (PD) were observed in 12 patients. Of the 12 patients, four with old myocardial infarction (OMI) had decreased %WT. All patients with OMI showed a decrease in %WT in the areas where PD was seen on the image. The other eight patients without OMI showed no decrease in %WT. In non-infarcted cases, the %WT was normal in the PD-positive area.

CONCLUSIONS

It is possible to evaluate myocardial ischemia and viability in KD patients by comparing PD on the image with %WT determined by QGS using exercise or drug-loaded myocardial scintigraphy alone.

Inter-institution preference-based variability of ejection fraction and volumes using quantitative gated SPECT with 99mTc-tetrofosmin: a multicentre study involving 106 hospitals

PURPOSE

Inter-institution reproducibility of gated SPECT quantification based on institutional preferences was evaluated. This sort of variability is crucial for a multicentre study when many hospitals are involved.

METHODS

A total of 106 institutes participated in this study and were grouped according to their use of five workstation types. Fifteen sets of 99mTc-tetrofosmin gated projection images with normal ejection fraction (EF) (approximately 70%, group A, n = 5), borderline low EF (approximately 50%, group B, n = 5) and low EF with large perfusion defects (approximately 30%, group C, n = 5) were prepared. The projection images were processed by QGS software in each institute based on its own routine settings. Based on 318 QGS results, the reproducibility of EF and volumes was analysed for each group and workstation.

RESULTS

The reproducibility of EF was good in 14 of 15 cases, showing a standard deviation (SD) of <3.6%, and the coefficient of variance of the end-diastolic volume (EDV) was <9.3% in all cases. When the deviation from the average value was analysed, the difference between EF at each institute and the average EF of the workstation (dEF) showed an SD of 2.2-3.7% for each group. The ratio of the EDV divided by the average EDV (rEDV) showed an SD of 0.061-0.069 for each group. One case in group C that had a large anterior defect with low EF showed bimodal EF distribution in one of the five workstations. The SD of EF was workstation dependent, owing to the SPECT reconstruction conditions.

CONCLUSION

The reproducibility in EF and volumes within a workstation was good, even though the gated SPECT preferences varied. This reproducibility study supports the use of gated SPECT as a standard of ventricular function in multicentre studies.

Evaluation of left ventricular volumes and ejection fraction by automated gated myocardial SPECT versus cardiovascular magnetic resonance

BACKGROUND

Electrocardiogram-gated myocardial single-photon emission computed tomography (SPECT) with (99m)Tc-tetrofosmin allows simultaneous evaluation of myocardial perfusion and function. In this study, left ventricular volumes, ejection fraction (LVEF), and left ventricular wall volume (LVWV) derived from gated SPECT were compared with measurements from cardiovascular magnetic resonance (CMR), performed within a few hours.

METHODS

The study population included 55 patients with known or suspected coronary artery disease, including 13 patients with recent acute myocardial infarction. End-diastolic (EDV) and end-systolic (ESV) volumes, LVEF and LVWV were derived automatically from gated SPECT using commercially available software (QGS). In the CMR studies, manually delineated endocardial and epicardial borders on short-axis slices were used to calculate the volumes.

RESULTS

Gated SPECT underestimated EDV by 35 +/- 14 ml (mean +/- SD) (P < 0.001), ESV by 10 +/- 13 ml (P < 0.001), and LVEF by 4 +/- 7 percentage points (P < 0.001). There were no systematic difference in EDV, ESV or LVEF between the methods. SPECT underestimated LVWV by 49 +/- 30 ml (P < 0.001), with a trend towards increasing underestimation by SPECT for larger wall volumes.

CONCLUSION

These findings show that gated SPECT slightly underestimates EDV, ESV and LVEF compared with CMR. This underestimation is systematic, however, indicating that ventricular volumes derived from gated SPECT are robust enough to guide clinical management. Estimates of LVWV in patients with large wall volumes are less accurate.

Gated SPECT assessment of left ventricular function is sensitive to small patient motions and to low rates of triggering errors: a comparison with equilibrium radionuclide angiography

BACKGROUND

Patient displacements and errors in R-wave detection are the main causes of inaccurate acquisition for gated single photon emission computed tomography (SPECT) and equilibrium radionuclide angiography (RNA). This study aimed to compare the influences of both factors between gated SPECT and RNA determinations of left ventricular ejection fraction.

METHODS AND RESULTS

On gated SPECT and RNA acquisitions, recorded in 20 patients with coronary artery disease, we simulated the consequences of (1) 3-dimensional patient displacements of low (6.7 mm), moderate (13.4 mm), and high amplitude (20.1 mm) and (2) an erroneous triggering on T waves in 10% to 40% of recorded beats. Absolute values of left ventricular ejection fraction changes from baseline were higher with gated SPECT compared with RNA for patient displacements of low amplitude (5.0% +/- 3.8% vs 1.2% +/- 0.9%, P < .001) or moderate amplitude (10.0% +/- 6.2% vs 3.0% +/- 2.3%, P = .001) but not for patient displacements of high amplitude (12% +/- 9% vs 9% +/- 7%, P = not significant) and inaccurate triggering (for 20% T-wave triggering, 8.9% +/- 3.6% vs 7.9% +/- 3.0%; P = not significant).

CONCLUSION

Contrary to RNA, gated SPECT is vulnerable to small patient displacements, and thus, specific efforts might be useful for limiting this potential cause of erroneous results. Both techniques may be affected by low rates of triggering errors, suggesting that small acceptance windows on cycle length should be recommended not only for RNA but also for gated SPECT.