The potential use of scout views as an adjunct tool in CT-guided intervention

The objective of this study was to evaluate the use of scout views as an adjunct tool in CT-guided intervention. Therefore, different devices used for interventional procedures were assigned to three different groups and placed onto an Alderson phantom. Different body diameters were simulated by adding PMMA/aluminum plates. Multiple scout views (ap) were acquired using a standard CT-scanner with different scan parameters. The visibility of the devices was semi-quantitatively scored by three readers. The interrater reliability was calculated using the intraclass correlation coefficient (ICC). The detectability of the 11 different interventional devices was calculated depending on tube potential, tube current-time product, and the thickness of the additional tissue equivalent. Statistical significance was evaluated using Wilcoxon signed-rank test (with Pratt modification) and the Mann-Whitney-U test, respectively. The ICC over all measurements for the three readers as well as the ICC for the three different devices groups was regarded excellent (> 0.9). The device detectability was significantly different for the different additional tissue thicknesses as well as for the three device groups. Material detectability over all readers improved with higher doses. Defining a median visibility of 3 ("good") or 4 ("very good") as a cut-off value for clinical routine use, we consider a combination of ≥ 80kVp / ≥ 60 mAs or ≥ 90 kVp / ≥ 40 mAs as reasonable scan parameters in normal and overweight patients in our CT setup. In conclusion, CT scout views have a potential use as an additional tool in CT-guided-intervention by enabling fluoroscopy-like planar imaging that may help to visualize dynamic events such as contrast injection or guidewire manipulation.