Normal left ventricular myocardial thickness for middle-aged and older subjects with steady-state free precession cardiac magnetic resonance: the multi-ethnic study of atherosclerosis

Abstract

Background: Increased left ventricular myocardial thickness (LVMT) is a feature of several cardiac diseases. The purpose of this study was to establish standard reference values of normal LVMT with cardiac magnetic resonance and to assess variation with image acquisition plane, demographics, and left ventricular function.

Methods and results: End-diastolic LVMT was measured on cardiac magnetic resonance steady-state free precession cine long and short axis images in 300 consecutive participants free of cardiac disease (169 women; 65.6 ± 8.5 years) of the Multi-Ethnic Study of Atherosclerosis cohort. Mean LVMT on short axis images at the mid-cavity level was 5.3 ± 0.9 mm and 6.3 ± 1.1 mm for women and men, respectively. The average of the maximum LVMT at the mid-cavity for women/men was 7/9 mm (long axis) and 7/8 mm (short axis). Mean LVMT was positively associated with weight (0.02 mm/kg; P=0.01) and body surface area (1.1 mm/m(2); P<0.001). No relationship was found between mean LVMT and age or height. Greater mean LVMT was associated with lower left ventricular end-diastolic volume (0.01 mm/mL; P<0.01), a lower left ventricular end-systolic volume (-0.01 mm/mL; P=0.01), and lower left ventricular stroke volume (-0.01 mm/mL; P<0.05). LVMT measured on long axis images at the basal and mid-cavity level were slightly greater (by 6% and 10%, respectively) than measurements obtained on short axis images; apical LVMT values on long axis images were 20% less than those on short axis images.

Conclusions: Normal values for wall thickness are provided for middle-aged and older subjects. Normal LVMT is lower for women than men. Observed values vary depending on the imaging plane for measurement.

Figure 1

Measurements obtained on long axis SSFP images of the septal (A), lateral (B), anterior (C) and inferior (D) left ventricular wall. After manually contouring the epicardial (green line in A–D) and endocardial (red line in A–D) border, myocardial thickness was automatically acquired in 100 measurements per left ventricular wall using the 2D centerline method (yellow lines in A–D).

Figure 2

Measurement obtained on a short axis SSFP image. After manually contouring the epicardial (green line) and endocardial (red line) border, left ventricular myocardial thickness was automatically acquired in 100 measurements per slice using the 2D centerline method (yellow lines).

Figure 3

Demonstration of measurement details by means of a vertical long axis cine SSFP image (A). Contours were placed on the center of the slightly blurred border zone (B, C) and on the center of the out-of-phase artifact along the epicardial surface of the myocardium (D, E).

Figure 4

Mean values of LVMT per level measured on long axis images and short axis images for 265 participants with a complete set of measurements. Comparison of the measurements obtained per level on short- and long axis images showed a significant difference (p<0.0001). p<0.02 statistically significant after Bonferroni correction.

Figure 5

Cine SSFP image at end-diastole acquired as 4 chamber view (A, C) and short axis view (B, D). The white line in A indicates the acquisition plane of the short axis image B and the white line in C corresponds to the acquisition plane of the short axis image D. On long axis images (A, C) endo- and epicardial border of the myocardium are clearly delineated at all levels while on short axis images of the apical level (B, D) myocardial borders are poorly defined and myocardial thickness appears greater compared to long axis.