Three-dimensional cardiac strain imaging in healthy children using RF-data

R. Lopata, M. Nillesen, J. Thijssen, L. Kapusta and C. de Korte

Cardiovascular Biomechanics, Department of BioMedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
Sep, 2011



In this study, a new radio-frequency (RF)-based, three-dimensional (3-D) strain imaging technique is introduced and applied to 3-D full volume ultrasound data of the heart of healthy children. Continuing advances in performance of transducers for 3-D ultrasound imaging have boosted research on 3-D strain imaging. In general, speckle tracking techniques are used for strain imaging. RF-based strain imaging has the potential to yield better performance than speckle- based methods because of the availability of phase information but such a system output is commercially not available. Furthermore, the relatively low frame rate of 3-D ultrasound data has limited broad application of RF-based cardiac strain imaging. In this study, the previously reported two-dimensional (2-D) strain methodology was extended to the third dimension. Three-dimensional RF-data were acquired in 13 healthy children, in the age range of 6-15 years, at a relatively low frame rate of 38-51 Hz. A 3-D, free-shape, coarse-to-fine displacement and strain estimation algorithm was applied to the RF-data. The heart was segmented using 3-D ellipsoid fitting. Strain was estimated in the radial (R), circumferential (C) and longitudinal directions (L). Our preliminary results reveal the applicability of the 3-D strain estimation technique on full volume 3-D RF-data. The technique enabled 3-D strain imaging of all three strain components. The average strains for all children were in the lateral wall R = 37 � 10\% (infero-lateral) and R = 32\% � 10\% (antero-lateral), C = -9\% � 4\% (antero-lateral) and C = -9\% � 4\% (infero-lateral), L = -18\% � 6 \% (antero-lateral) and L = -15\% � 4\% (infero-lateral). In the septum, strains were found to be R = 24\% � 10\% (antero-septal) and R = 13\% � 5\% (infero-septal), C = -13\% � 5\% (antero-septal) and -13\% � 5\% (infero-septal) and L = -13\% � 3\% (antero-septal) and L = -16\% � 5\% (infero-septal). Strain in the anterior and inferior walls seemed underestimated, probably caused by the low (in-plane) resolution and poor image quality. The field-of-view as well as image quality were not always sufficient to image the entire left ventricle. It is concluded that 3-D strain imaging using RF-data is feasible, but validation with other modalities and with conventional 3-D speckle tracking techniques will be necessary.