Assessment of left ventricular function with 16- and 64-slice multi-detector computed tomography.

BACKGROUND

Important to the risk stratification and management of cardiac patients is the assessment of left ventricular function (LVEF), thus imaging modalities which can provide both anatomical and functional data is desirable. Electrocardiographic (ECG) gated multi-detector computed tomographic (MDCT) images may provide accurate assessment of LV ejection fraction, volume and dimensions but have shown systemic errors in the past due to slow gantry rotation speed.

METHODS

Between May 2004 and January 2005, 306 patients underwent ECG-gated cardiac CT studies at the Massachusetts General Hospital. Patients with available CT data sets and a recent (within 3 months) ECHO and/or SPECT perfusion imaging were included in the study. ECG-gated data sets were acquired either with a 16-slice or with a 64-slice MDCT. Functional MDCT data sets were reconstructed in 10 cardiac phases (5-95%) with 1.5mm slices. Images were processed and interpreted by two observers blinded to ECHO and SPECT results.

RESULTS

A total of 69 patients had MDCT and ECHO or SPECT within 3 months (33 had 16-slice and 36 had 64-slice MDCT). There was fair correlation between LVEF measured by 16-slice MDCT and 'ECHO or SPECT' (62+/-10% vs. 62+/-10%; r=0.56). There was poor correlation between LVEF measured by 16-slice MDCT and ECHO (64+/-10% vs. 59+/-11%; r=0.26) and there was good correlation between LVEF measured by 16-slice MDCT and SPECT (62+/-11% and 64+/-9%, respectively; r=0.76). There was very good correlation between LVEF measured by 64-slice MDCT and 'ECHO or SPECT' (57+/-15% vs. 58+/-13%; r=0.86). There was very good correlation between LVEF measured by MDCT and ECHO (56+/-14% vs. 54+/-15%; r=0.89) and between LVEF measured by 64-slice MDCT and SPECT (60+/-13% and 60+/-14%, respectively; r=0.90).

CONCLUSION

The assessment of LVEF and LV dimensions with 64-slice MDCT provide values which are similar to those obtained by echocardiography and Tc-99m gated SPECT. The accuracy of the 64-slice MDCT with a gantry rotation speed of 330 ms (when compared to ECHO and SPECT) may be superior to that of the 16-slice MDCT at 420 ms gantry rotation.