Original article
Gated blood pool tomoscintigraphy with 4-dimensional optical flow motion analysis quantifies left ventricular mechanical activation and synchronization

https://doi.org/10.1016/j.nuclcard.2006.07.009Get rights and content

Background

Gated blood pool tomoscintigraphy has the unique capacity to accurately assess myocardial motion in paced patients. Our goal was to develop a precise radionuclide angiography analysis of cardiac dynamics to evaluate ventricular synchronization in patients undergoing biventricular pacing.

Methods and Results

On the basis of a 4-dimensional deformable motion estimation algorithm, we developed a protocol allowing estimation of motion fields after gated blood pool tomoscintigraphy. We measured the mechanical activation times for 17 left ventricular (LV) segments and determined the main types of contraction pattern in 10 normal subjects, 17 patients with dilated cardiomyopathy, and 12 resynchronized patients. We analyzed intra-LV dyssynchrony: apex to base, septum to lateral wall, and anterior wall to inferior wall. Three-dimensional measurements of intra-LV activation time (r > .80, P < .001) and LV ejection fraction (r > 0.90, P < .0001) are linearly correlated to 2-dimensional values. LV contraction follows the electrical activation pattern. In normal subjects the anteroseptal and anterior segments are first activated, followed by the apex and inferolateral segments. In resynchronized patients contraction begins with the lateral and apicoseptal segments in correspondence to the LV and right ventricular lead implantation.

Conclusions

By measuring mechanical activation times, this technique allows for the analysis of the regional synchronous contraction. This may help to assess the variation of the activation pattern according to the cardiomyopathy type and the role of septal resynchronization in ventricular functional recovery.

Section snippets

Materials and methods

On the basis of a deformable motion estimation algorithm,10, 11 we developed a protocol allowing voxel-by-voxel estimation of motion fields after GBPT. We measured the mechanical activation times for the 17 LV segments (American Heart Association classification12) and determined the main types of activation pattern in normal subjects and in heart failure patients before and after multisite pacing.

Phase Analysis

Mechanical activation times are represented in Table 1. The intraventricular phase analysis showed a good correlation between 2D RNA and GBPT: r = 0.64 (P < .0001) for the apex-to-base time, r = 0.65 (P = .0003) for the inferior wall–to–anterior wall time, and r = 0.62 (P < .001) for the septum–to–lateral wall time.

Total Activation Time

An excellent correlation was obtained for the time differences between the peaks of the first and last segments in GBPT and the phase histogram width in 2D RNA (r = 0.82, P < .0001) (

Phase Analysis

In this investigation we demonstrate that 3D phase analysis can quantify LV synchronization. According to Scher,16 the sequence of ventricular activation reveals an early and almost simultaneous activation of the central left side of the septum and the high anterior and apicoposterior paraseptal LV areas, followed by the remainder of the septum and the LV and RV free walls. Our results, showing a twist motion of the left ventricle, with the anterior area, followed by the anterolateral area, the

Acknowledgment

The authors have indicated they have no financial conflicts of interest.

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