Automatic Global and Regional Phase Analysis from Gated Myocardial Perfusion SPECT Imaging: Application to the Characterization of Ventricular Contraction in Patients with Left Bundle Branch Block

Abstract

Although many patients with heart failure benefit from cardiac resynchronization therapy (CRT), predicting which patients will respond to CRT remains challenging. Recent evidence suggests that the analysis of mechanical dyssynchrony using gated myocardial perfusion SPECT (MPS) may be an effective tool. The aim of this study was to evaluate global and regional gated MPS dyssynchrony measurements by comparing parameters obtained from patients with a low likelihood (LLk) of conduction abnormalities and coronary artery disease and patients with left bundle branch block (LBBB). Methods: A total of 86 consecutive patients with LLk and 72 consecutive patients with LBBB, all without prior myocardial infarction or sternotomy, were studied using gated MPS. Global (histogram SD [s], bandwidth [b], and entropy [e]) and regional (wall-and segment-based differences of means [Dm W and Dm S , respectively] or modes [DM W and DM S , respectively]) dyssynchrony measures were calculated by Fourier harmonic phase-angle analysis of local myocardial count variations over the cardiac cycle for each patient, and then unpaired t tests were used to determine which parameters were sex-specific and how well they discriminated between the LLk and LBBB populations. Receiver-operating-characteristic analysis was also performed to calculate the area under the curve (AUC), sensitivity (Ss), specificity (Sp), and optimal threshold (Th). Results: Global parameters were found to be sex-specific, whereas regional differences were sex-independent. All parameters studied showed statistically significant differences between the groups (all global, P , 0.05; all regional, P , 0.0001). Receiver-operating-characteristic analysis yielded higher AUC, Ss, and Sp for e and regional parameters (e: AUC 5 The computed parameters all discriminate effectively between LLk and LBBB populations. Measurements that are less dependent on the shape of the phase-angle distribution histogram provided higher sensitivity and specificity for this purpose. Further study is needed to evaluate these parameters for the purpose of predicting response to CRT.Key Words: left ventricular dyssynchrony; left bundle branch block; cardiac resynchronization therapy; myocardial perfusion gated SPECT

Quantitative Gated SPECT–Derived Phase Analysis on Gated Myocardial Perfusion SPECT Detects Left Ventricular Dyssynchrony and Predicts Response to Cardiac Resynchronization Therapy

“…Particularly, observational trials have shown the significance of LV dyssynchrony for the prediction of response to CRT (6)(7)(8). LV dyssynchrony can be detected using different imaging modalities, including echocardiography with tissue Doppler imaging (TDI) (6)(7)(8) or strain (rate) imaging (11), MRI (12), and nuclear imaging with single photon emission computed tomography (SPECT) (13)(14)(15)(16)(17)(18). In particular, phase analysis on gated myocardial perfusion SPECT (GMPS) has been evaluated recently for the assessment of LV dyssynchrony (14)(15)(16)(17)(18).…”

Electrocardiogram-Gated 18F-FDG PET/CT Hybrid Imaging in Patients with Unsatisfactory Response to Cardiac Resynchronization Therapy: Initial Clinical Results

“…We did find that our responder group had slightly lower phase entropy, which is a mathematic expression of synchrony not relying on phase similarity. Consequently, in contrast to phase bandwidth and SD (22), phase entropy is not influenced by boundary histogram bars-phase entropy is a reflection of the variability of synchrony during the ventricular contraction. O'Connell et al recently reported that LV entropy measurements in a gated blood-pool SPECT study were superior to phase SD for distinguishing healthy subjects from patients with LV aneurysm or diffuse or regional ventricular dysfunction (21).…”

Ventricular asynchrony: A shift to the right?

“…A slightly different approach that imposes constant myocardial mass constraints was developed for Quantitative Gated SPECT (QGS) software, 15 the BW and SD measurements of which successfully separated normal patients from those with LBBB. 16 Correlations between phase parameters from GMPI SPECT and tissue Doppler were modest, …”

“…A slightly different approach that imposes constant myocardial mass constraints was developed for Quantitative Gated SPECT (QGS) software, 15 the BW and SD measurements of which successfully separated normal patients from those with LBBB. 16 Correlations between phase parameters from GMPI SPECT and tissue Doppler were modest, partly because GMPI phase is a global measurement, while TDE represents single points and parameters. 17 GMPI phase SD and BW have the advantage of being highly reproducible and repeatable.…”