Reliability of enhanced gated SPECT in assessing wall motion of severely hypoperfused myocardium: echocardiographic validation

4D display of CT LV endocardial and epicardial models morphed from PET Rb-82 perfusion studies accurately quantifies segmental myocardial thickening

BACKGROUND

MPI-derived LV wall thickening assessments for diagnostic purposes has been part of clinical guidelines for two decades. It relies on visual evaluation of tomographic slices or regional quantification displayed in 2D polar maps. 4D displays have not entered clinical usage nor have they been validated on their potential to provide equivalent information. The purpose of this work was to validate a 4D realistic display recently designed to quantitatively represent the thickening information from gated MPI into CT-morphed endocardial and epicardial moving surfaces.

METHODS

Forty patients who underwent 82Rb PET were selected based on LV perfusion quantification. CTA templates of heart anatomy were selected to represent the LV anatomy. Generic CT-derived LV endocardial and epicardial surfaces were modified to represent the end diastolic (ED) phase according to PET-derived ED LV dimensions and wall thickness. These CT myocardial surfaces were then morphed by means of thin plate spline (TPS) techniques, according to the gated PET slices count changes (WThPET) and LV wall motion (WMoPET). A geometric thickening (GeoTh) equivalent to LV WThPET was defined on epicardial and endocardial CT surfaces over the cardiac cycle and the two measures compared. WThPET and GeoTh correlations were performed on a case-by-case basis, by segment and by pooling all 17 segments. Pearson's correlation coefficients (PCC) were calculated to assess the equivalence of the two measures.

RESULTS

Two cohorts of patients (normal and abnormal) were identified based on SSS. R coefficients were as follows: for all pooled segments PCCstress and PCCrest were respectively 0.91 and 0.89 (normal), and 0.9 and 0.91 (abnormal); when individual 17 segments were considered mean PCCstress = 0.92 [0.81-0.98] and mean PCCrest = 0.93 [0.83-0.98] for the abnormal perfusion group; mean PCCstress = 0.89 [0.78-0.97] and mean PCCrest = 0.89 [0.77-0.97] for the normal. When individual studies were considered, R was always > .70 with the exception of five abnormal studies. Inter-user analysis was also conducted.

CONCLUSIONS

Our novel technique for the visualization of LV wall thickening by means of 4D CT endocardial and epicardial surface models accurately replicated 82Rb slice thickening results showing promise for its usage for diagnostic purposes.

Reducing the small-heart effect in pediatric gated myocardial perfusion single-photon emission computed tomography

BACKGROUND

We compared two reconstruction algorisms and two cardiac functional evaluation software programs in terms of their accuracy for estimating ejection fraction (EF) of small hearts (SH).

METHODS

The study group consisted of 66 pediatric patients. Data were reconstructed using a filtered back projection (FBP) method without the resolution correction (RC) and an iterative method based on an ordered subset expectation maximization (OSEM) algorithm with the RC. EF was evaluated using two software programs of quantitative gated single-photon emission computed tomography (SPECT) (QGS) and cardioREPO. We compared the EF of gated myocardial perfusion SPECT to echocardiographic measurement (Echo).

RESULTS

Forty-eight of 66 patients had an end-systolic volume < 20 mL which was used as the criterion for being included in the SH group, and the SH effect led to an overestimation of EF. While significant differences were observed between Echo (66.9 ± 5.0%) and QGS-FBP without RC (76.9 ± 8.4%, P < .0001), QGS-OSEM with RC (76.6 ± 8.6%, P < .0001), and cardioREPO-FBP without RC (72.1 ± 10.0%, P = .0011), no significant difference was observed between Echo and cardioREPO-OSEM with RC (67.4 ± 6.1%) in SH group.

CONCLUSIONS

In pediatric gated myocardial perfusion SPECT, the SH effect can be significantly reduced when an OSEM algorithm is used with RC in combination with the specific cardioREPO algorithm.

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.

Comparative values of gated blood-pool SPECT and CMR for ejection fraction and volume estimation

OBJECTIVE

Gated blood-pool single-photon emission computed tomography (GBPS) was compared with cardiac magnetic resonance (CMR) for the measurement of left ventricular (LV) and right ventricular (RV) ejection fractions (EF) and volumes [end-diastolic volume (EDV) or end-systolic volume (ESV)] in a mixed population.

METHODS

Thirty patients (70% men; mean age: 61±14 years) referred for various symptoms or heart diseases, predominantly ischemic, were included. GBPS data were analyzed using segmentation software described earlier based on the watershed algorithm. CMR images were acquired for both ventricles at the same time using a steady-state-free precession sequence and short-axis views. No compensation for papillary muscles was used. LVEF and RVEF and volumes were assessed with GBPS and CMR and were compared.

RESULTS

LVEF and volumes were correlated (P<0.001). The difference in LVEF between GBPS and CMR was not significant (P=0.063). The limits of agreement were close for LVEF (-11 to 15%) and wider for LV volumes (-82 to 11 ml for EDV and -52 to 15 ml for ESV), with higher volume values obtained with CMR (mean differences of 36±24 ml for EDV and 19±17 ml for ESV). The RVEF and volumes assessed by GBPS and CMR were correlated (P<0.001). The difference in RVESV between GBPS or CMR was not significant (P=0.136). The limits of agreement were relatively close for all RV parameters (-15 to 8% for EF; -44 to 22 ml for EDV, and -25 to 21 ml for ESV). In 24 patients without valvulopathy or shunt, the difference between LV stroke volume and RV stroke volume was lower with GBPS than with CMR (9±14 ml and 18±13 ml, respectively, with P=0.027).

CONCLUSION

GBPS is a simple and widely available technique that can assess both LVEF and RVEF, and volumes with slight differences compared with CMR.

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.

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.

Assessment of left ventricular function and volumes for patients with dilated cardiomyopathy using gated myocardial perfusion SPECT and comparison with echocardiography

AIM

Left ventricular function, volumes and regional wall motion provide valuable diagnostic information and are of long-term prognostic importance in patients with dilated cardiomyopathy (DCM). This study was designed to compare the effectiveness of two-dimensional echocardiography and gated single photon emission computed tomography (SPECT) to evaluate these parameters in patients with DCM.

METHODS

Gated SPECT and two-dimensional echocardiography were performed in 45 patients with DCM, and in 10 normal subjects as the control group. Patients were divided into two groups according to the aetiology of DCM: group I, ischaemic DCM (n=30); group II, non-ischaemic DCM (n=15). All patients and the control group underwent resting myocardial gated SPECT, 45 min after injection of 555 MBq of Tc-methoxyisobutyl-isonitrile (Tc-MIBI). Gated SPECT data, including left ventricular volumes and left ventricular ejection fraction (LVEF), were processed using an automated algorithm. Simpson's method was used to evaluate these parameters. Regional wall motion was evaluated using both modalities and scored using a 16-segment model with a five-point scoring system. Perfusion defects were expressed as a percentage of the whole myocardium planimetered by a bull's-eye polar map of composite non-gated SPECT. Myocardial perfusion was scored using a 16-segment model with a four-point scoring system.

RESULTS

Mean perfusion defects and perfusion defect scores were 25+/-13% and 1.12+/-0.36 in group I and 4+/-8% and 0.76+/-0.26 in group II (P<0.01). The overall agreement between the two imaging modalities for the assessment of regional wall motion was 57% (403/720 segments: 269/480 segments in group I and 134/240 segments in group II). With gated SPECT, LVEF was 27+/-9%, the end-diastolic volume (EDV) was 212+/-71 ml and the end-systolic volume (ESV) was 160+/-67 ml. With echocardiography, these values were 29+/-8%, 197+/-56 ml and 139+/-47 ml, respectively. The correlation between gated SPECT and two-dimensional echocardiography was good (r=0.72, P<0.01) for the assessment of LVEF. The correlation was also good for EDV and ESV, but with wider limits of agreement (r= 0.71, P<0.01 and r=0.71, P<0.01, respectively) and with significantly higher values with gated SPECT (P<0.01). For patients with a perfusion defect of <20% or low myocardial perfusion scores, a higher correlation was found between the two methods for the assessment of LVEF, EDV and ESV. On the other hand, the correlation was lower for the assessment of wall motion.

CONCLUSIONS

Gated SPECT and two-dimensional echocardiography correlate well for the assessment of left ventricular function and volumes. Gated SPECT has the advantage of providing information about left ventricular function, dimensions and perfusion.

Evaluation of left ventricular function and volume in patients with dilated cardiomyopathy: gated myocardial single-photon emission tomography (SPECT) versus echocardiography

BACKGROUND

Left ventricular function, volumes and regional wall motion provide valuable diagnostic information and are of long-term prognostic importance in patients with dilated cardiomyopathy (DCM). This study was designed to compare the effectiveness of 2D-echocardiography and gated single-photon emission tomography (SPECT) for evaluation of these parameters in patients with DCM.

PATIENTS AND METHODS

Gated SPECT and 2D-echocardiography were performed in 33 patients having DCM. Gated SPECT data, including left ventricular volumes and left ventricular ejection fraction (LVEF), were processed using an automated algorithm. Standard technique was used for 2D-echocardiography. Regional wall motion was evaluated using both modalities and was scored by two independent observers using a 16-segment model with a 5-point scoring system.

RESULTS

The overall agreement between the two imaging modalities for the assessment of regional wall motion was 56% (298/528 segments). With gated SPECT, LVEF, end-diastolic volume (EDV), and end-systolic volume (ESV) were 27+/-9%, 217+/-77 mL, and 163+/-73 mL, respectively, and 30+/-8%, 195+/-58 mL, and 137+/-48 mL with echocardiography. The correlation between gated SPECT and 2D-echocardiography was good (r=0.76, P<0.01) for the assessment of LVEF. The correlation for EDV and ESV were also good, but with wider limits of agreement (r=0.72, P<0.01 and r=0.73, P<0.01, respectively) and significantly higher values were obtained with gated SPECT (P<0.01).

CONCLUSIONS

Gated SPECT and 2D-echocardiography correlate well for the assessment of LV function and LV volumes. Like 2D-echocardiography, gated SPECT provides reliable information about LV function and dimension with the additional advantage of perfusion data.

Comparison of myocardial gated single photon emission computerised tomography, planar radionuclide ventriculography and echocardiography in evaluating left ventricular ejection fraction, wall thickening and wall motion

Left ventricular ejection fraction (LVEF) and wall thickening are fundamental aspects of cardiac function. Recently, gated single photon emission computerised tomography (GSPECT) and anatomical M-mode echocardiography are new techniques, which have been introduced for the evaluation of left ventricular wall thickening and ejection fraction. These, however, have not been evaluated against established techniques, including equilibrium radionuclide ventriculography (ERNV), which remains the current gold standard for the evaluation of LVEF. We examined the concordance between LVEF, wall motion and wall thickening scores derived from GSPECT, echocardiography and ERNV, in a group of 16 patients with suspected ischaemic heart disease. Estimated ejection fraction correlated better between ERNV and gated SPECT (R2 = 0.93) than between echocardiography and either gated SPECT (R2 = 0.62) or ERNV (R2 = 0.71). There was poor correlation between gated SPECT and anatomical M-mode echocardiography in the assessment of wall thickening (83/150, 56%; kappa= 0.31, p < 0.05) and similar correlation (100/150, 66%; kappa = 0.29, p < 0.01) for wall motion analysis. In conclusion, estimations of ejection fraction by all the three studied modalities agreed to a degree sufficient for routine clinical practice. However, estimates of wall thickening from echocardiography cannot be used interchangeably with those derived from gated myocardial perfusion SPECT.

Comparison of gated planar Tc-99m tetrofosmin scintigraphy with radionuclide ventriculography and echocardiography in the evaluation of left ventricular wall motion

Assessment of ventricular function is an important diagnostic and prognostic tool in coronary heart disease (CHD). The objective of this study was to compare radionuclide ventriculography (RVG), echocardiography (ECHO) and gated planar tetrofosmin myocardial scintigraphy (GPTF) in patients with CHD. Radionuclide ventriculography in left anterior oblique (LAO) and left lateral (LLT) projections was performed in 44 patients. Two days later, rest tetrofosmin perfusion tomoscintigraphy (SPECT) and rest GPTF in RVG identical parameters and projections were acquired. Within the two following days, the patients underwent two-dimensional ECHO. GPTF studies were processed and interpreted in original (NI-GPTF) and image inverted, RVG like form (I-GPTF). All visual interpretations were evaluated with a semi-quantitative scoring system. Quantitative analysis was performed on parametric images by means of segmental regions of interest. Linear regression and contingency analysis were carried out in overall analysis and on a segmental basis separately by accepting the RVG as the standard for the whole investigation. In overall cine-mode evaluation, NI-GPTF (r = 0.77, p < 0.001, complete agreement (CA) = 84%) was superior to I-GPTF (r = 0.73, p < 0.001, CA = 82%) and ECHO (r = 0.39, p < 0.001, CA = 78%), compared to RVG. On a segmental basis, NI-GPTF showed the best RVG-correlations except for inferoapical, mid-inferior, mid-anterior and anterobasal segments. In visual analysis of functional images, the best RVG-agreement was observed in I-GPTF (r = 0.72, p < 0.001, CA = 77%). On a segmental basis, I-GPTF showed the best RVG-correlations except for posterolateral, mid-inferior, mid-anterior and anterobasal segments. In overall quantitative evaluation, amplitude values in both I-GPTF (r = 0.76, p < 0.001) and NI-GPTF (r = 0.75, p < 0.001) studies were well correlated with RVG amplitude. I-GPTF gave the best RVG-correlation of phase (r = 0.59, p < 0.001). The mean phase and standard deviation RVG-correlations of I-GPTF were r = 0.92, p < 0.001 and r = 0.53, p < 0.001 respectively. In segmental quantification, amplitude values of all segments in I-GPTF were better RVG-correlated than in NI-GPTF. In conclusion, GPTF could be a time saving alternative to ECHO in the evaluation of wall motion by the nuclear medicine physician. Because of differing segmental RVG correlations, NI-GPTF and I-GPTF should be both interpreted to improve the diagnostic value of the method. Cine-mode and parametric image interpretations in GPTF studies should be done simultaneously since the former is more closely correlated to RVG.

Electrocardiogram-gated single-photon emission computed tomography versus cardiac magnetic resonance imaging for the assessment of left ventricular volumes and ejection fraction: a meta-analysis

OBJECTIVES

The purpose of this study was to evaluate the accuracy of electrocardiogram (ECG)-gated single-photon emission computed tomography (SPECT) for assessment of left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) compared with the gold standard of cardiac magnetic resonance imaging (MRI).

BACKGROUND

Several comparisons of ECG-gated SPECT with cardiac MRI have been performed for evaluation of LV volumes and EF, but each has considered few subjects, thus leaving uncertainty about the frequency of discrepancies between the two methods.

METHODS

We performed a meta-analysis of data on 164 subjects from nine studies comparing ECG-gated SPECT versus cardiac MRI. Data were pooled in correlation and regression analyses relating ECG-gated SPECT and cardiac MRI measurements. The frequency of discrepancies of at least 30 ml in EDV, 20 ml in ESV and 5% or 10% in EF and concordance for EF < or =40% versus >40% were determined.

RESULTS

There was an overall excellent correlation between ECG-gated SPECT and cardiac MRI for EDV (r = 0.89), ESV (r = 0.92) and EF (r = 0.87). However, rates of discrepancies for individual subjects were considerable (37% [95% confidence interval [CI], 26% to 50%] for at least 30 ml in EDV; 35% [95% CI, 23% to 49%] for at least 20 ml in ESV; 52% [95% CI, 37% to 63%] for at least 5% in EF; and 23% [95% CI, 11% to 42%] for at least 10% in EF). The misclassification rate for the 40% EF cutoff was 11%.

CONCLUSIONS

Electrocardiogram-gated SPECT measurements of EDV, ESV and EF show high correlation with cardiac MRI measurements, but substantial errors may occur in individual patients. Electrocardiogram-gated SPECT offers useful functional information, but cardiac MRI should be used when accurate measurement is required.

Detection of residual wall motion after sustained myocardial infarction by gated 99Tcm-tetrofosmin SPECT: a comparison with echocardiography

The differentiation of residual viability from necrotic myocardium in patients with a previously sustained myocardial infarction is important in deciding indications for revascularization. Myocardial viability can be assessed by studying perfusion and regional wall motion. With gated single photon emission computed tomography (SPECT), it is possible to augment SPECT perfusion data with ventricular functional data both at a global and regional level. The aim of the study was to analyse the concordance between wall motion score derived by gated SPECT and echocardiography. Furthermore, the agreement between myocardial perfusion and left ventricular wall motion was analysed with both techniques. We studied a homogenous group of 25 consecutive patients with a previous myocardial infarction (MI) using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and two-dimensional echocardiography. Echocardiography was performed within 2 weeks of the gated SPECT study. Both for gated SPECT and for echocardiography the left ventricle was divided into seven regions per patient. For comparison, the gated SPECT regions were matched to the echocardiographic regions, resulting in a total of 175 regions. Prevalence of abnormal wall motion (akinetic or dyskinetic) was 23% (39/171) for echocardiography and 21% (36/175) for gated SPECT (P = NS). There was a high agreement in wall motion score between echocardiography and gated SPECT of 80% (136/171). The agreement between myocardial perfusion and myocardial wall motion was 82% (143/175) for gated SPECT and 76% (130/171) for echocardiography (P = NS). Nineteen (34%) of the 56 regions with severely diminished or absent myocardial perfusion showed normal or hypokinetic wall motion both by gated SPECT and echocardiography suggesting residual myocardial viability in malperfused regions. Our results suggest that, gated SPECT imaging is a reliable tool for the assessment of regional wall motion in post myocardial infarction patients. Furthermore, in patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion in regions with fixed perfusion defects, which might be indicative of residual myocardial viability.

The additive value of gated SPET myocardial perfusion imaging in patients with known and suspected coronary artery disease

In myocardial perfusion scintigraphy, the clinical significance of fixed defects presents some difficulty. In this study, we evaluated whether additional information on left ventricular function assessed by quantitative gated single-photon emission computed tomography (gated SPET) would increase the diagnostic yield of the study in such patients. We studied 55 patients with a previous myocardial infarction and 20 patients without a previous myocardial infarction using gated SPET 99Tc(m)-tetrofosmin myocardial perfusion imaging. Each patient had to have a persistent perfusion defect consisting of at least three contiguous segments in the same vascular territory. The left ventricle was divided into 20 segments which were analysed for perfusion and wall thickening on a 4-point severity scale. Of the 55 patients with myocardial infarction, 19 (35%) patients showed preserved wall thickening in the region of the previous infarction with fixed perfusion abnormalities, which suggested residual myocardial viability. In the 20 patients without myocardial infarction, preserved wall thickening was seen in 10 (50%) patients with fixed perfusion defects, suggesting an attenuation artefact. Conversely, in 16 (29%) patients in the myocardial infarction group and two (10%) patients in the non-myocardial infarction group normal perfusion was associated with severely diminished wall thickening possibly due to stunning. We found an excellent correlation between wall thickening and left ventricular ejection fraction both for the patients with myocardial infarction and the patients without myocardial infarction (r = 0.86 and r = 0.82, respectively, both P<0.0001). A reasonable correlation between perfusion and left ventricular ejection fraction was found for the patients with myocardial infarction (r = 0.41, P = 0.002), and a non-significant correlation for the patients without myocardial infarction (r = 0.37, P = 0.1). Quantitative gated SPET myocardial imaging allows the detection of residual wall thickening in patients with a previous myocardial infarction who show severe fixed perfusion defects. In patients without myocardial infarction, gated SPET imaging allows differentiation between an attenuation artefact and a fixed perfusion defect due to coronary artery disease. In addition, gated SPET may show diminished ventricular function in normally perfused segments possibly due to myocardial stunning. The addition of gated SPET myocardial perfusion imaging increases diagnostic confidence and may have direct clinical implications for optimal patient management.

Two- and three-dimensional assessments of myocardial perfusion and function by using technetium-99m sestamibi gated SPECT with a combination of count- and image-based techniques

BACKGROUND

Although the myocardial gated single photon emission computed tomography (SPECT) technique makes it possible to assess concurrent myocardial perfusion and function, quantitative methods for analyzing and displaying gated SPECT data in 2- and 3-dimensional presentations for regional and global cardiac assessment have not been established.

METHODS AND RESULTS

We have developed an automated quantitative method for assessing perfusion and function by means of technetium-99m sestamibi gated SPECT with a computerized technique combining count-based and image-based methods. We have examined its validity in 91 patients by comparing its results with those of conventional techniques: contrast left ventriculography and radionuclide angiocardiography. In addition to color-scale displays of regional function, simultaneous 3-dimensional presentations of regional wall motion and perfusion have been produced. High reproducibility of gated SPECT analysis with this algorithm was demonstrated; interoperator errors (%CV) were 2.6% to 5.5%, and good intraobserver reproducibility was confirmed by means of high correlation coefficients (0.954 to 0.989). Left ventricular volumes assessed by means of contrast left ventriculography and by means of the gated SPECT technique showed significant correlations (left ventricular end-diastolic volume, y = 1.01x - 9.7, r = 0.845, P<.001, standard errors of the estimate [SEE] = 14 mL; left ventricular end-systolic volume, y = 1.03x - 1.4, r = 0.902, P<.001, SEE = 6 mL). Left ventricular ejection fraction determined by means of gated SPECT with the new algorithm closely correlated with that determined by means of radionuclide ventriculography (y = 1.05x - 0.6, r = 0.891, P<.001, SEE = 3 %). These parameters quantified by means of the present method correlated closely with those derived from the QGS program (r = 0.926 to 0.987).

CONCLUSION

In comparison with conventional techniques, myocardial gated SPECT with automated quantitative analysis provides accurate and reproducible data for global and regional function. Quantitative concurrent assessment of myocardial perfusion and function by using 2-and 3-dimensional representations appears to be superior to other modalities and to contribute to nuclear cardiology practice.

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 electrocardiographic-gated technetium-99m sestamibi single-photon emission computed tomographic imaging and rest-redistribution thallium-201 in the prediction of myocardial viability

Although the combined assessment of perfusion and function using rest electrocardiographic (ECG)-gated technetium-99m (Tc-99m) sestamibi single-photon emission computed tomographic (SPECT) imaging has been shown to improve sensitivity and accuracy over perfusion alone in the prediction of myocardial viability, no data are available comparing this technique with rest-redistribution thallium-201. Thirty patients with coronary artery disease and left ventricular dysfunction (ejection fraction < or = 40%) underwent rest-redistribution thallium-201 and rest ECG-gated Tc-99m sestamibi SPECT imaging before revascularization and rest ECG-gated Tc-99m sestamibi SPECT imaging at 1 or 6 weeks after revascularization. All thallium-201 and Tc-99m sestamibi images were interpreted by a consensus agreement of 3 experienced readers without knowledge of patient identity or time of imaging with Tc-99m sestamibi (before or after revascularization) using a 17-segment model. Concordance between techniques for the prediction of viability was 89% (kappa 0.556 +/- 0.109). With rest-redistribution thallium-201, sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 95%, 59%, 88%, 78%, and 86%, respectively. With rest ECG-gated Tc-99m sestamibi SPECT imaging, sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 96%, 55%, 87%, 80%, and 86%, respectively (p = NS vs rest-redistribution thallium-201). Although both techniques are comparable for detecting viable myocardium, rest ECG-gated Tc-99m sestamibi SPECT imaging allows direct assessment of both myocardial perfusion and ventricular function, which may be clinically useful in patients who require assessment of myocardial viability.

Gated SPECT imaging

Gated SPECT imaging has allowed the simultaneous assessment of both perfusion and function through one study. The popularity of this is amply shown by the unprecedented growth of this imaging modality throughout the country. In addition to the benefits that ventricular function adds to perfusion, gated SPECT imaging also adds to the specificity of perfusion imaging. With recent studies showing the benefit of medical therapy to interventional approaches for the treatment of patients with angina, in particular, patients with chronic stable angina, there has been an increased dependence on noninvasive imaging to assess their ischemic burden. Perfusion, with technetium-99m sestamibi SPECT imaging together with gated SPECT imaging has been the modality of choice in the majority of cases because of the ease of performance of these studies and the increased information provided. This has in large part been attributable to the ability of gated SPECT imaging to provide functional data, significantly increasing the use of radionuclide perfusion imaging. This article reviews the method of acquisition, validation, clinical use, and the newer advances of gated SPECT imaging. It gives an appreciation of the benefit that gated SPECT imaging has added in terms of risk stratification and prognosis in many cardiac patients. Under the more recent uses are myocardial viability and the increased utility of gating in this scenario, ischemic versus nonischemic cardiomyopathies, and the quandary that this testing poses to physicians and the dilemma of gated thallium imaging with its inferior image quality.