Quantification of Circumferential, Longitudinal, and Radial Global Fractional Shortening Using Steady-State Free Precession Cines: A Comparison with Tissue- Tracking Strain and Application in Fabry Disease June Cheng-Baron, 1 Kelvin Chow, 1 Joseph J. Pagano, 1 Kumaradevan Punithakumar, 2 D. Ian Paterson, 3 Gavin Y. Oudit, 3 and Richard B. Thompson 1 * Purpose: Conventional calculation of myocardial strain requires tissue-tracking. A surrogate for strain called global fractional shortening (GFS) is proposed based on changes in dimensions of endocardial and epicardial surfaces without tis- sue-tracking. Methods: Three-dimensional endocardial and epicardial left ventricular surfaces traced at end-diastole and end-systole using conventional steady-state free precession cine images were used to calculate GFS cc (circumferential), GFS ll (longitudi- nal), and GFS rr (radial) using fractional length changes in each direction over the heart surface. GFS values were validated using finite element models (FEM) and in vivo using tagging- derived strains (e cc ,e ll ,e rr ) in patients with a wide range of ejec- tion fraction (EF) and diagnosis (n ¼ 32). GFS was also meas- ured in 31 patients with Fabry disease and matched healthy controls. Results: GFS values were within 3% of average FEM-derived Lagrangian strains and had good agreement in vivo (GFS cc ¼14 6 4%, e cc ¼14 6 4%, R 2 ¼ 0.85; GFS ll ¼12 6 4%, e ll ¼12 6 4%, R 2 ¼ 0.72; GFS rr ¼ 46 6 21%). e rr could not be measured reliably from tagging. Compared with healthy controls with matched EF, patients with Fabry disease had sig- nificantly increased GFS cc (Endo) (28 6 3% versus 25 6 2%), decreased GFS cc(Epi) (10 6 2% versus 11 6 2%) and decreased GFS ll for all components. Conclusion: GFS yields similar values to conventionally meas- ured strains without requiring tissue-tracking. Compared with controls, patients with Fabry disease have significant differen- ces in several GFS components. Magn Reson Med 73:586– 596, 2015. V C 2014 Wiley Periodicals, Inc. Key words: myocardial strain; fractional shortening; SSFP cine; MRI INTRODUCTION Left ventricular (LV) ejection fraction (EF) is the most commonly reported measure of cardiac performance. However, it is now widely accepted that abnormalities in morphology and function may exist despite preserved LVEF. Specifically, changes in global LV longitudinal strain, which is the average of regionally derived strain, have been shown to exist without detectable changes in circumferential strain or LVEF in hypertension with heart failure (1), heart transplant recipients (2), type 2 diabetes (3), aortic regurgitation (4), hypertrophic cardiomyopathy (5), Fabry disease (6,7), and with cardio- toxicity in patients undergoing anthracycline and trastu- zumab breast cancer therapy (8,9). Global longitudinal strain has also been shown to be a better predictor than wall motion score index or LVEF for all-cause mor- tality (10). Echocardiography is routinely used to measure strain with techniques such as tissue Doppler (11) and speckle tracking (12) due in large part to rapid data acquisition and online postprocessing methods, often reporting the average or global strain as the primary measure (1–10). Quantitative strain measurement using MRI tissue tagging (13–16), phase contrast imaging (17), displacement-mapping (18) or direct strain mapping (19) are widely used in focused research studies but are not routine in clinical MRI due to the necessity for additional data acquisition and potentially onerous postprocessing. Recently, feature tracking algorithms have been applied to MRI steady-state free precession (SSFP) cines. This method is appealing because myocardial tissue deformation information can be obtained without the acquisition of additional tagged or otherwise encoded images. However, specialized software is necessary to perform the tracking (20–23), and while acceptable inter- observer and intraobserver reproducibility has been shown (21,23,24), interstudy reproducibility has been shown to be less reliable (25). In the current article an alternative method, termed global fractional shortening (GFS), is proposed to esti- mate peak global systolic longitudinal, circumferential and radial strain using the same end-systolic and end- diastolic endocardial and epicardial contours as conven- tional method of disks LV volume analysis, with mini- mal additional postprocessing. It is proposed that GFS values are similar to the corresponding global strain component calculated as the mean of regional strains. GFS values were validated by comparison to strain derived using finite element analysis in heart models and by comparison to conventional tissue tagging- derived strains in subjects with a wide range of 1 Department of Biomedical Engineering, University of Alberta, Edmonton, Canada. 2 Servier Virtual Cardiac Centre, Mazankowski Alberta Heart Institute and Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Canada. 3 Division of Cardiology, University of Alberta, Edmonton, Canada. *Correspondence to: Richard B. Thompson, Ph.D., Department of Biomedi- cal Engineering, University of Alberta, Edmonton, Alberta, Canada. E-mail: richard.thompson@ualberta.ca Received 10 July 2013; revised 11 January 2014; accepted 13 January 2014 DOI 10.1002/mrm.25166 Published online 13 March 2014 in Wiley Online Library (wileyonlinelibrary. com). Magnetic Resonance in Medicine 73:586–596 (2015) V C 2014 Wiley Periodicals, Inc. 586