Objective    To assess the performance of multi-detector CT (MDCT) to evaluate left atrial and left atrial appendage volume and function

and compare the results by cardiac cine MR (CMR).     Methods    Forty-eight patients who were referred for clinically-indicated CT coronary angiography in our department from March to December 2008

were included in the study.

MDCT data sets (Somatom Definition

Siemens Medical Solutions

Forchheim

Germany) and fast imaging employing steady-state acquisition ( FIESTA ) cines (Signa Excite HD 3T

GE ) of the vertical long axis covering the left atrium were obtained on the same day. All images were analyzed to obtain the maximum and minimum of left atrial volume (LAV

max

  and LAV

min

)

the maximum and minimum of left atrial appendage volume (LAAV

max

and LAAV

min

)

left atrial ejection fraction (LAEF)

and left atrial appendage ejection fraction (LAAEF) using Heart Function software and Report Card 2.0 software

respectively

for MDCT and CMR. Intermodality agreement was tested through linear regression and t test. Interobserver variability were tested by Bland-Altman analyses.     Results    MDCT measurements resulted in good correlation (r0.75) compared with CMR. However

MDCT has a tendency to overestimate LAV

max

LAV

min

LAAV

max

and LAAV

min

and to underestimate LAEF and LAAEF but insignificantly. The interobserver variability in the MDCT measurements was lower than that of CMR values.     Conclusion    MDCT provides highly reliable and reproducible measurements of left atrial and left atrial appendage volume and function in patients referred for coronary CT imaging.