Individualized scan protocols for CT angiography: an animal study for contrast media or radiation dose optimization

BackgroundWe investigated about optimization of contrast media (CM) dose or radiation dose in thoracoabdominal computed tomography angiography (CTA) by automated tube voltage selection (ATVS) system configuration and CM protocol adaption.MethodsIn six minipigs, CTA-optimized protocols were evaluated regarding objective (contrast-to-noise ratio, CNR) and subjective (6 criteria assessed by Likert scale) image quality. Scan parameters were automatically adapted by the ATVS system operating at 90-kV semi-mode and configured for standard, CM saving, or radiation dose saving (image task, quality settings). Injection protocols (dose, flow rate) were adapted manually. This approach was tested for normal and simulated obese conditions.ResultsRadiation exposure (volume-weighted CT dose index) for normal (obese) conditions was 2.4 +/- 0.7 (5.0 +/- 0.7) mGy (standard), 4.3 +/- 1.1 (9.0 +/- 1.3) mGy (CM reduced), and 1.7 +/- 0.5 (3.5 +/- 0.5) mGy (radiation reduced). The respective CM doses for normal (obese) settings were 210 (240) mgI/kg, 155 (177) mgI/kg, and 252 (288) mgI/kg. No significant differences in CNR (normal; obese) were observed between standard (17.8 +/- 3.0; 19.2 +/- 4.0), CM-reduced (18.2 +/- 3.3; 20.5 +/- 4.9), and radiation-saving CTAs (16.0 +/- 3.4; 18.4 +/- 4.1). Subjective analysis showed similar values for optimized and standard CTAs. Only the parameter diagnostic acceptability was significantly lower for radiation-saving CTA compared to the standard CTA.ConclusionsThe CM dose (-26%) or radiation dose (-30%) for thoracoabdominal CTA can be reduced while maintaining objective and subjective image quality, demonstrating the feasibility of the personalization of CTA scan protocols.