Quantification of synchronous contraction of left ventricle in normal subjects using ECG-gated-SPECT images

Improvement of Left Ventricular Asynchrony: Cases of Functional Recovery After Revascularization

Assessment of regional contraction is considered important for diagnosis of coronary artery disease (CAD). We evaluated the synchronicity in regional contraction and assessed recovery from contraction insufficiency after revascularizations. Myocardial contraction parallel to the left ventricular (LV) wall was calculated using the method called quantification of segmental function by solving the Poisson equation (QSFP) from an electrocardiogram (ECG)-gated (99m)Tc-methoxyisobutylisonitrile (MIBI) single-photon emission computed tomographic (ECG-SPECT) image. Myocardial synchronous contraction was quantified using the synchronous contraction index (SCI), defined as the temporal correlation coefficient between LV volume and regional myocardial shortening. SCI was evaluated in 20 subjects, of whom 10 had CAD and 10 were normal. ECG-SPECT was performed in all the CAD patients before and after revascularization. In the 10 patients with CAD, the mean SCI before the revascularization was 62.7 ± 19.1%, which was significantly lower than that in the normal subjects (95.0 ± 3.0%, p = 0.002). After revascularization, a significant improvement in SCI was recorded (74.8 ± 11.1%, p = 0.01). The territorial improvement in SCI was 12.0 ± 15.6% (p = 0.03). Locations of abnormal cardiac contraction due to CAD were delineated by using QSFP. Therefore, SCI can be considered a valuable index for cardiac function assessment.

Analytical method to measure three-dimensional strain patterns in the left ventricle from single slice displacement data

BACKGROUND

Displacement encoded Cardiovascular MR (CMR) can provide high spatial resolution measurements of three-dimensional (3D) Lagrangian displacement. Spatial gradients of the Lagrangian displacement field are used to measure regional myocardial strain. In general, adjacent parallel slices are needed in order to calculate the spatial gradient in the through-slice direction. This necessitates the acquisition of additional data and prolongs the scan time. The goal of this study is to define an analytic solution that supports the reconstruction of the out-of-plane components of the Lagrangian strain tensor in addition to the in-plane components from a single-slice displacement CMR dataset with high spatio-temporal resolution. The technique assumes incompressibility of the myocardium as a physical constraint.

RESULTS

The feasibility of the method is demonstrated in a healthy human subject and the results are compared to those of other studies. The proposed method was validated with simulated data and strain estimates from experimentally measured DENSE data, which were compared to the strain calculation from a conventional two-slice acquisition.

CONCLUSION

This analytical method reduces the need to acquire data from adjacent slices when calculating regional Lagrangian strains and can effectively reduce the long scan time by a factor of two.