{'fraction_non_alphanumeric': 0.06239737274220033, 'fraction_numerical': 0.05966064586754242, 'mean_word_length': 4.730407523510972, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Feasibility study of the best monitoring time-interval to track contrast agent bolus in dual-source coronary computed tomography angiography

Background : To identify the best time - interval for dual - source coronary computed tomography angiography (CCTA) with bolus tracking automatic trigger technique. Materials and Methods : 120 patients were randomly divided into four groups (A, B, C and D), with 30 patients in each group. Monitoring was begun 10 seconds after injection, and the monitoring time - intervals for groups A, B, C and D were 1.14, 1.47, 2.00 and 3.00 seconds, respectively. CCTA acquisition was triggered as the monitored concentration in the region of interest (ROI) exceeded 100 HU. The monitoring times, CT and dose length product (DLP) values of the four groups were compared statistically. The quality of recorded CCTA images was evaluated objectively, and the image quality of blood vessel segments was accessed subjectively. Results : there were no statistically significant differences in objective evaluations between the four groups (P>0.05). Subjective evaluation results showed no statistically significant differences between groups A (1.879±0.042), B (1.876±0.043) and C (1.881±0.052). Group D showed the highest subjective score (2.923±0.069), which was significantly different from groups A, B, and C (P<0.01). The monitoring times for groups A, B, C and D were 4.78±2.37, 3.76±1.39, 2.77±0.99 and 2.38±0.64, respectively; and the DLP values were 4.13±2.22, 2.18±0.80, 1.50±0.51 and 1.48±0.43 mGy·cm, respectively. DLP increases with increased monitoring times. Conclusion : When performing dual - source CCTA, a monitoring time - interval of 2 seconds with trigger scanning technique is the best choice, since it effectively reduces the radiation dose while providing satisfactory images.