Background: Myocardial strain is useful for early detection of left ventricular myocardial (LVM) damage but is usually determined by 2 dimensional (2D) speckle tracking TTE. A novel prototype software program (Physiodynamics, Ziosoft) can calculate 3D strain values in LVM using existing 320 slice CT, which is in daily clinical use.
Purpose: To evaluate the usefulness of myocardial strain analysis on CT for detection of myocardial fibrosis in cases with hypertrophic cardiomyopathy (HCM).
Methods: Eighteen consecutive HCM patients who underwent 320 slice CT (Aquilion One), 2D speckle tracking transthoracic echocardiography (TTE) (Vivid E9, GE Healthcare), and 1.5T or 3T cardiac magnetic resonance (CMR) (Ingenia or Achieva) were analyzed. Cardiac CT was performed with retrospective ECG gaging with tube current dose modulation. After acquisition, CT images were reconstructed at every 5% of the R-R interval from 0–95% (total, 20 phases). We compared the detectability of a new 3D CT myocardial strain values with that of regional peak longitudinal and circumferential strain (PLS and PCS) on TTE to detect late gadolinium enhancement (LGE) in the LVM on CMR. On CT, the 3D strain ratio (3DSR; segmental 3D strain-value per maximum segmental 3D strain-value in each patient) of each LVM segment was calculated. On TTE, PLS and PCS (both absolute values) for each LVM segment among 17 American Heart Association-defined lesions were calculated.
Results: Using receiver operating characteristic (ROC) analysis for the detection of LGE on CMR, the best cut off value of 3DSR was 0.3 with area under the curve (AUC) of 0.88 (P<0.0001), a sensitivity of 84% and a specificity of 84%. While that of PLS was 12 with an AUC of 0.68 (P<0.0001), a sensitivity of 78% and a specificity of 53%, and that of PCS was 15 with an AUC of 0.51 (P=0.913), a sensitivity of 49% and a specificity of 58%. The AUC was significantly greater in CT than in PLS and in PCS of TTE (both P<0.01).
Conclusion: 3DSR determined by existing CT has a significantly superior detectability for LGE in LVM on CMR than PLS and PCS in HCM patients.