▁which ▁ultimately ▁transl ates ▁into ▁a ▁> 6 0 % ▁change ▁in ▁L V ▁e jection ▁fraction . ▁Left ▁vent ric ular ▁she aring ▁increases ▁towards ▁the ▁sub end oc ard ium , ▁resulting ▁in ▁a ▁sub ep ic ard ial ▁to ▁sub end oc ard ial ▁thick ening ▁stra in ▁gradient . ▁Similar ▁to ▁M RI , ▁S TE ▁util izes ▁" L agr ang ian ▁stra in " ▁which ▁defines ▁motion ▁around ▁a ▁particular ▁point ▁in ▁t issue ▁as ▁it ▁revol ves ▁through ▁time ▁and ▁space . ▁Through out ▁the ▁card iac ▁cycle , ▁the ▁end - di ast ol ic ▁t issue ▁dimension ▁represents ▁the ▁un str essed ▁initial ▁material ▁length . ▁Spe ck le ▁tracking ▁is ▁one ▁of ▁two ▁methods ▁for ▁St rain ▁rate ▁imag ing , ▁the ▁other ▁being ▁T issue ▁Do pp ler . ▁ ▁Tw ist ▁or ▁t ors ional ▁de formation ▁define ▁the ▁base - to - ape x ▁gradient ▁and ▁is ▁the ▁result ▁of ▁my oc ard ial ▁she aring ▁in ▁the ▁circum fer ential - long itud inal ▁plan es ▁such ▁that , ▁when ▁viewed ▁from ▁the ▁a pe x , ▁the ▁base ▁rot ates ▁in ▁a ▁counter clock wise ▁direction . ▁Like wise ▁the ▁L V ▁a pe x ▁con com it antly ▁rot ates ▁in ▁a ▁clock wise ▁direction . ▁During ▁e jection , ▁L V ▁t ors ion ▁results ▁in ▁the ▁storage ▁of ▁potential ▁energy ▁into ▁the ▁de formed ▁my of ib ers . ▁This ▁stored ▁energy ▁is ▁released ▁with