ABSTRACT
Objective To investigate the value of the adaptive statistical iterative reconstruction (ASIR) algorithm for reducing the radiation dose and optimizing the image quality in the low-dose spectral CT scanning in GSl (Gemstone spectral imaging) of the liver.Methods A total of 60 patients who underwent hepatic spectral CT scanning in GSI were enrolled in this study.The patients were randomly divided into two groups according to priority with 30 cases per group.Low-dose spectral CT scanning was used for group A, and images were reconstructed by ASIR 0 and 50％ , marked as A1 and A2.Group B was scanned with conventional dose of spectral CT, and images were reconstructed by Filtered back projection (FBP).Effective doses (E) for each group were calculated.Image quality was assessed by two radiologists, and the radiation doses were compared between groups A and B.Results All image quality of each group were good enough for clinical diagnosis.E for group A and B were (3.2 ±0.2) and (5.8 ± 0.2) mSv, respectively.There was statistical difference with image noise between group A and B(Z =-6.784,P ＜ 0.05).The image noise, SNR and CNR had statistical differences between group A and B (F =24.013, 15.646, 8.285, P ＜0.05).Compared with group A1, the image noise was lower, and the SNR and CNR were higher in groups A2 and B(P ＜ 0.05).There were no statistical differences of image noise, SNR and CNR between groups A2 and B (P ＞ 0.05).There were no statistical differences of the image quality score between groups A1, A2 and B (F =102.38,105.768, P ＜ 0.05).Conclusions ASIR combined with low-dose spectral CT scanning was helpful to reduce radiation dose and could obtain better image quality in hepatic CT examination.
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Objective To investigate the influence of TRF on high-intensity cerebrospinal fluid artifacts in T2-FLAIR MR imaging.Methods In a GE Signa Twinspeed 1.5T system,50 cases were examined with T2-FLAIR sequences including 2 different optional imaging parameters according to the augmentation of TRF.Results TRF pulses significantly improved image quality(P
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Objective To evaluate mini-dose pre-injection test in the use of contrast-enhanced magnetic resonance angiography (CEMRA), and to inspect the possibility of contrast medium peak-time prediction by age, body weight and heart rate.Methods The data from mini-dose pre-injection test of contrast medium before vertebral artery CEMRA were retrospectively reviewed in 55 patients. The linear correlation and regression of the data including age, body weight, heart rate, and the reaching-time, peak-value-time, duration and peak-value-signal of contrast medium was performed by using SPSS software.Results The age (n=55, =62 years old, M=59 years old), body weight (n=55, = 63 kg), heart rate (n=40, =73 beats per minute), peak-value-time (n=55,=17.5 seconds), peak signal intensity (n=55,=472), and duration of contrast (n=49,=10.35 seconds)were analyzed. No statistically significant correlation existed between peak-value-time of contrast medium and the age (r=0.231, t=1.728, P=0.090), body weight (r=0.118, t=0.865, P=0.392), and heart rate (r= -0.046, t=-0.284, P=0.776). The peak-value-time correlated negatively with peak signal intensity (r=-0.322, t=-2.56, P=0.016)and positively with duration of contrast (r=0.658, t=5.99, P=0.000). The peak signal intensity was negatively correlated with body weight(r=-0.356, t=-2.77, P=0.008). The linear regression analysis show b=-0.284, t=-2.285, P=0.026 between peak-value-signal and peak-value-time, b=-0.322, t=2.590, P=0.012 between peak-value-signal and body weight.Conclusion Mini-dose pre-injection test was more helpful to adjust the rate of contrast medium injection and determine the time delay during scanning. But the prediction of contrast peak-time based on age, body weight and heart rate was unreliable.