Objective: The objective of this study was to assess the effect of wall thickness, density of intravascular contrast material, and size of the display field of view on the accuracy of measurements of vascular diameter in phantoms yielded by automated software for CT angiography.
Materials and methods: Vascular models with three wall thicknesses (1.0, 0.8, and 0.5 mm) and an inner diameter of approximately 4 mm were filled with contrast material of three different densities (198, 270, and 350 H) and scanned with helical CT. Three sizes of display field of view (10, 15, and 20 cm) were used. We evaluated the measurement error of the automated software, which was defined as the difference between the diameter measurement of the automated software and the true inner diameter of the vascular model. Statistical analysis involved three-way analysis of variance with repeated measures.
Results: There were significant differences in the measurement errors among the three wall thicknesses of the vascular model, three densities of intravascular contrast material, and three sizes of display field of view. The overall measurement errors progressively increased with larger sizes of display field of view (p < 0.01) and with lower densities of intravascular contrast material (p < 0.001). The measurement errors tended to progressively increase as the thickness of the wall of the vascular models increased.
Conclusion: The accuracy of the diameter measurements by automated software for CT angiography was affected by the size of the display field of view, intravascular density of the contrast material, and wall thickness of the vessel. It is necessary to consider the effects of these factors on the diameter measurements of small arteries.