Three-dimensional analysis of left ventricle regional wall motion by using gated blood pool tomography

Assessment of an intermediate reprojection technique transitioning from planar to SPECT radionuclide ventriculography

BACKGROUND

The technique of SPECT-RNV (radionuclide ventriculography) offers a greater amount of clinically usable data than its planar counterpart (P-RNV). In transitioning from planar to SPECT-only acquisition methodologies, reprojection of the SPECT data can provide a planar dataset which can be used as an interim technique. The aim of this study was to test if reprojected planar images could be used as a surrogate for true planar images in SPECT-only setting.

METHODS

We performed SPECT-RNV and P-RNV on 47 patients on traditional sodium iodide (NaI) cameras, determining left ventricular ejection fractions (LVEF) for planar (EFP) and SPECT (EFS) techniques. We reprojected the SPECT-RNV data along the best septal separation angle determined from planar scanning. This creates a further planar dataset denoted 'reprojected P-RNV' (rP-RNV) giving a reprojected ejection fraction (EFR) which can be used as a validation variable in transitioning to SPECT-only acquisition.

RESULTS

Performing t tests showed no statistical difference between EFP and EFR (P > .017) but bias was observed in EFS results compared to EFP and EFS compared to EFR results. An unblinded, comparison of parametric data between the three datasets for a subset of ten patients showed good clinical concordance. False negative and false positive rates were low for rP-RNV compared to P-RNV.

CONCLUSIONS

The reprojected planar LVEF correlates well to P-RNV EF values. The rP-RNV dataset can aid clinicians in transitioning from planar RNV to SPECT-only acquisition.

Interventricular delay measurement using equilibrium radionuclide angiography before resynchronization therapy should be performed outside the area of segmental wall motion abnormalities

BACKGROUND

The aim of this study was to demonstrate that only mechanical dyssynchrony outside the area of segmental wall motion abnormalities (WMA) can be reduced by cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

Included in the study were 28 consecutive patients with nonischaemic cardiomyopathy selected for CRT. Equilibrium radionuclide angiography (ERNA) was carried out before and after implantation of a multisite pacemaker. Patients were separated into two groups depending on the presence or absence of segmental WMA.

RESULTS

A reduction in QRS duration was observed in all patients after CRT. The interventricular delay (IVD) decreased significantly after CRT only in patients without WMA (homogeneous contraction, HG group; IVD 44 ± 11.4° vs. 17 ± 3.1°, p = 0.04). In contrast, no significant decrease was observed in patients with WMA (WMA group; IVD 51 ± 6° vs. 38 ± 6°, p NS). However, when dyssynchrony was considered outside the WMA area, a significant reduction in IVD was obtained, in the same range as in the HG group (IVD 32 ± 3° vs. 19 ± 3°, p = 0.04). In 9 of 15 patients (60%) with a reduction in IVD after CRT, the left ventricle ejection fraction (LVEF) increased by about +10%. In contrast, in 13 of 13 patients (100%) with no reduction in IVD, no modification of LVEF was obtained. In the presence of segmental WMA without significant delays outside the WMA area, no reduction in IVD was observed and LVEF did not increase (IVD 34 ± 5° before CRT vs. 37 ± 7° after CRT; LVEF 19 ± 4% before CRT vs. 22 ± 3% after CRT, p NS).

CONCLUSION

ERNA can be used to predict good mechanical resychronization (decrease in IVD) in patients after pacing. IVD has to be determined excluding the area of WMA in order to select patients who will show an increase in their left ventricle function after CRT.

SPECT versus planar gated blood pool imaging for left ventricular evaluation

BACKGROUND

We developed a new segmentation algorithm based on the invariance of the Laplacian (IL) to compute volumes and ejection fractions and compared these results with planar analysis and gradients by use of a standard algorithm (QBS).

METHODS AND RESULTS

Planar and single photon emission computed tomography blood pool acquisition was performed in 202 patients. Planar left ventricular ejection fraction (LVEF) was used as the gold standard, and single photon emission computed tomography images were processed by both 3-dimensional (3D) methods. Correlations between each 3D algorithm and planar methodology were as follows: r = 0.77 for QBS and r = 0.84 for IL. Mean LVEFs were 32.72% +/- 13.05% for the planar method, 32.32% +/- 15.98% for QBS, and 31.93% +/- 13.44% for IL (P = .16). Bland-Altman analysis closely demonstrated negligible systematic bias for both 3D methods. Standard errors of bias were comparable between methods (9.36% for QBS and 7.44% for IL, P = .48). Linear regression of the Bland-Altman bias revealed a slope significantly different from 0 for the QBS method (0.22 +/- 0.048, P < .0001) but not for IL (-0.032 +/- 0.0044, P = .47).

CONCLUSION

The new segmentation algorithm provides comparable results to QBS and planar analysis. However, with QBS, the difference in LVEF was correlated with the magnitude of LVEF, which was not found with the new algorithm.

Segmental Wall Motion Abnormality Analyzed by Equilibrium Radionuclide Angiography and Improvement in Ventricular Function by Cardiac Resynchronization Therapy

INTRODUCTION

The purpose of this study was to determine the impact of the left ventricular (LV) segmental wall motion abnormalities detected by equilibrium radionuclide angiography (ERNA) on the improvement in LV and right ventricular (RV) function during biventricular (BIV) stimulation.

RESULTS

We studied 28 patients in NYHA functional classes III or IV and QRS duration > 150 ms on resting electrocardiogram. ERNA was performed before and during BIV stimulation at a 6-month follow-up. A significant shortening of QRS duration was observed during BIV stimulation (165 +/- 5 ms before vs 133 +/- 6 ms during, P < 0.01). Wall motion abnormalities (WMA) were observed in 16 patients (10 with nonischemic cardiomyopathies). In this group, LV and RV ejection fractions (EF) did not increase during BIV stimulation (LVEF = 22 +/- 2% vs 20 +/- 1.6%, ns; RVEF = 34 +/- 3% vs 37 +/- 3.8%, ns). Significant increases in RVEF (23 +/- 3.2% --> 38 +/- 2.9%, P = 0.001) and LVEF (20 +/- 2.5% --> 30 +/- 3%, P = 0.01) were observed in the group of patients without segmental WMA and with global hypokinesia (GH). In this group, a significant decrease in the dispersion in the phase of RV contraction was observed (SD = 39 +/- 5 vs 26 +/- 2 ms; P < 0.01). WMA predicted an increase in LVEF, in contrast to a baseline 6-minute-walk test, maximal oxygen consumption and LVEF, or amount of QRS shortening.

CONCLUSIONS

BIV stimulation increased in LV and RV EF in patients with ventricular dyssynchrony in absence of segmental WMA. ERNA was reliable in the selection of candidates for CRT.

Clinical validation of the gated blood pool SPECT QBS processing software in congestive heart failure patients: correlation with MUGA, first-pass RNV and 2D-echocardiography

INTRODUCTION

Left (LVEF) and right ventricular ejection fraction (RVEF) as well as LV regional wall motion at rest are valuable tools to monitor and tailor treatment of congestive heart failure (CHF) patients. Gated blood pool SPECT (GBPS) is under evaluation as an "all-in-one" technique, providing information on LVEF, RVEF, and wall motion derived from a single examination. Aim of the study was to evaluate a commercially available automated GBPS processing software for EF measurements and wall motion analysis in heart failure patients.

METHODS

Thirty-two patients (12 female; mean age+/-SD: 53+/-13 years), suffering from dilated (63%), ischemic (25%) or hypertrophic (13%) cardiomyopathy, were studied. First-pass radionuclide ventriculography (FP-RNV), planar multigated radionuclide angiography (MUGA), and GBPS were performed at rest after in vivo labeling of red blood cells, and LVEF and RVEF was calculated with each method. Later on the same day LVEF was calculated by echocardiography. LV wall motion (summed motion score and wall motion index) was derived from GBPS and echocardiography using the standard 16-segment model.

RESULTS

Mean LVEF measured by GBPS, echocardiography, MUGA and FP-RNV was 33+/-13%, 37+/-15%, 41+/-14% and 45+/-13%, respectively. LVEF values calculated from GBPS showed moderate to good correlation with FP-RNV (r=0.61), MUGA (r=0.65) and ECHO (r=0.74; all p<0.01). Mean RVEF calculated by GBPS, FP-RNV and MUGA was 45+/-14%, 46+/-9% and 38+/-9%, respectively. RVEF values calculated from GBPS showed weak correlation with FP-RNV (r=0.33) and MUGA (r=0.26; all p=n.s.). Assessment of GBPS wall motion was qualitatively possible in all patients. The agreement between GBPS and ECHO was 82% (kappa=0.73). The wall motion index showed good correlation between both methods (r=0.88; p<0.001).

CONCLUSION

An automated algorithm for LVEF calculation and wall motion analysis using GBPS is feasible for clinical routine diagnostic in CHF patients. The RVEF calculation method needs to be improved before routine clinical application can be recommended.