Model-free reconstruction of 3-D myocardial strain from planar tagged MR images: precision and spatial resolution

A technique is presented for reconstructing a three-dimensional myocardial strain map from a set of parallel-tagged magnetic resonance images. This technique was demonstrated on high resolution tagging data from an anesthetized dog. The strain was reconstructed with a precision of ±6.0% for a tag detection accuracy of 0.1 mm and a tag spacing of 2.5 mm. The reconstruction spatial resolution was demonstrated by reconstructing a displacement field in response to a displaced cloud of tag points. In the circumferential direction, the cloud that resulted in a 50% displacement attenuation had a full width at half maximum (FWHM) of 5.4mm±0.4mm (mean ± standard deviation). The FWHM of the strain field reconstructed from a single in plane displaced tag point was 5.2mm±0.3mm. It is concluded that the combination of high-resolution parallel-tagged MR images and the model-free, coordinate system-free strain reconstruction technique presented is capable of producing accurate, high-resolution strain maps of the myocardium