ABSTRACT
Objective To investigate the feasibility of reducing bolus?tracking monitor frequency in coronary CT angiography (CTA). Methods This prospective study including 120 patients with suspected coronary artery disease (CAD). According to the examination registration order, the patients were divided into groups A, B and C (n=40 for each group). All patients underwent coronary CTA with bolus?tracking technology, and were monitored at 10 s after the injection of contrast. The monitoring frequency of bolus?tracking for Group A was every 1.14 s, that for Group B was every 1.47 s , and for Group C was every 2.00 s, while the trigger threshold was set as 100 HU. To evaluate the image quality, the objective evaluation included signal noise ratio (SNR) and contrast noise ratio (CNR) of aorta (AO), CNR of left main coronary artery (LM) and right coronary artery (RCA), and the subjective score was recorded for each coronary artery segment. The monitoring times when CT density of the region of interest (ROI) reached the threshold, the CT value and the effective dose (ED) in the 3 groups were recorded. Objective image quality, monitoring parameters and radiation dose were compared using analysis of variance method, subjective image quality was compared withχ2 tests. Results There was no significant difference in AO (SNR and CNR), LM (CNR) and RCA (CNR) among the 3 groups, respectively (P>0.05). Subjective image quality scores of groups A, B, C were (1.879±0.042), (1.876±0.042), (1.881±0.042 ), with no significant difference (χ2=0.003,P>0.05). The monitoring times of to reach the threshold in groups A, B, C were (4.78±2.37), (3.76±1.39), (2.77±0.99), and ED were (0.058±0.031),(0.031±0.011), (0.021±0.007) mSv, with the significant difference (F=9.009, 31.998, respectively, P<0.01). Peak CT values during monitoring among three groups were (133 ± 24), (142 ± 39), (137±26) HU, respectively, with no significant difference (F=0.575,P=0.565). Conclusions It is feasible to reduce monitoring times when performing coronary CTA in dual?source CT scanner. The bolus?tracking monitor frequency in every 2 seconds can not only obtain satisfactory image quality, but also significantly reduce radiation dose.