Analysis of left ventricular function, left ventricular outflow tract and aortic valve area using computed tomography: Influence of reconstruction parameters on measurement accuracy.

OBJECTIVES

Computed tomography (CT) allows reproducible assessment of left ventricular (LV) function, left ventricular outflow tract area (LVOT) and aortic valve area (AVA). We evaluated the influence of image reconstruction parameters on these measurements.

METHODS

We analyzed 45 contrast-enhanced, retrospectively ECG-gated CT datasets acquired on a third-generation dual source system. A standard filtered-back-projection data set (20 cardiac phases (5% steps, 0-95%), 0.6-mm-slice thickness, 512 × 512 matrix) and eight reconstructions with modified slice thickness (1-8 mm), number of cardiac phases (5, 10), matrix size (256×256) and an iterative reconstruction (IR) algorithm were obtained. LV parameters (ejection fraction (EF), stroke volume (SV), end-diastolic (EDV), end-systolic volumes (ESV)), LVOT and AVA were assessed.

RESULTS

Differences in LV parameters, LVOT and AVA, were only minimal between standard reconstructions and those with modified matrix size, IR algorithm and ≤2 mm slice thickness, while reconstructions with 8-mm slice thickness significantly overestimated SV ( < 0.001) and EDV ( = 0.016). AVA planimetry in reconstructions with ≥5 mm slice thickness was not feasible in 56% of patients. A decrease in the number of reconstructed phases (10 or 5) underestimated EF, SV, EDV, LVOT and AVA and overestimated ESV.

CONCLUSIONS

Modifications of reconstruction parameters (except a slice thickness ≤2 mm) have only a marginal effect on LV, LVOT and AVA assessment. However, a reduced number of reconstructions per cardiac cycle may significantly influence measurements.

ADVANCES IN KNOWLEDGE

Substantial modifications in number of reconstructions per cardiac cycle significantly affect the assessment of LV function, LVOT and AVA also in modern CT scanners.