Flat panel computed tomography for non-invasive flow measurement: initial results in in-vitro studies

The purpose was to evaluate the feasibility of flat panel computed tomography (FPCT) for quantifying flow by analyzing contrast changes along the z-axis in an in-vitro setting. Contrast material was injected in a 3-mm silicone tube at flow rates of 0.1, 0.2, 0.5 and 1.0 ml/s using a commercially available injector pump. FPCT scans of this phantom were performed with a gantry rotation time of 3 s. From this data 41 phases were reconstructed at different points in time using a full and a partial gantry rotation. The differences in the contrast material arrival time and the contrast enhancement along the z-axis were recorded. Flow was calculated from this data and compared to the injector settings. There was a good agreement between the injector settings and the calculated flow rates, but agreement decreased with increasing flow rates. Absolute (percent) mean deviation between the injector settings and calculated flow values was 0.0230 +/- 0.0489ml/s (3.7243 +/- 4.7817%) using the full gantry rotation. Repeated-measurement ANOVA failed to show significant differences between the various techniques (p = 0.9726). FPCT allows for computing flow. While preliminary results indicate a good agreement at low flow rates, further studies are needed to assess this technique for higher flow rates.