Image quality and diagnostic value of ultra low-voltage, ultra low-contrast coronary CT angiography

Objective To explore the image quality (IQ) and diagnostic value of 70kVp turbo high-pitch coronary CT angiography (THP-CCTA) using automated tube voltage selection (ATVS) and 30mL of low-concentration contrast agent. Methods Patients who underwent 70kVp THP-CCTA using ATVS with 30mL of contrast agent (group A) were prospectively enrolled, and those who underwent conventional CCTA (100/120kVp, prospective sequential mode with 65-75mL of contrast agent) (group B) were retrospectively selected for study. IQ was assessed subjectively on a 5-point scale, and diagnostic value was assessed based on invasive coronary angiography as the gold standard. Heart rate (HR), HR fluctuation (HRF), body mass index (BMI), effective radiation dose (ED), and iodine uptake (IU) were recorded. Results A total of 796 patients (398/398 in groups A/B) were included. Between-group differences in age, gender, BMI, HR, HRF, and IQ values were not significant. The ED/IU values were 0.3 +/- 0.1 mSv/9.0 +/- 0.0 g and 5.8 +/- 1.8 mSv/22.9 +/- 1.0 g in groups A and B, respectively (p<0.01). The sensitivity, specificity, positive and negative predictive values, and accuracy of THP-CCTA for the diagnosis of >= 50% stenosis were 94.8%, 97.5%, 92.0%, 98.4%, and 96.9% respectively. The mean HR and coronary calcium score were independent predictors of diagnostic image quality, and the best cutoff values were 71.5bpm and 444.1 respectively. Conclusion This third-generation dual-source CT imaging modality, a 70-kVp THP-CCTA system using ATVS with 30mL of low-concentration contrast agent, produces high-quality images with high diagnostic accuracy for significant stenosis, with ultra low ED and IU. This technique was most promising in individuals with an HR <71.5 bpm and coronary calcium score <444.1.