| Objective Explore the feasibility of gem low-dose CT perfusion imaging with low scanning time and low contrast agent concentration.Methods Animal experiment: Using animal model experiments the feasibility of low dose, low dose perfusion experiment. 20 healthy adult white rabbit respectively, each with fixed tube voltage of 80 kv and three sets of tube current 80,50,10 ma,cerebral CT perfusion. Using adaptive statistical algorithm(ASIR), effective dose of three groups(E), and perfusion parameters of CBF, CBV, MTT, and function of signal-to-noise ratio(SNR) to compare with, and the subjective evaluation of image quality. Clinical trials : A group, in the same clinical classification screening and 60 to chronic cerebral ischemia patients were randomly divided into three groups, fixed tube voltage is 80 kv, tube current 150,100,80 ma respectively perfusion imaging. Using ASIR weighting algorithm, also more effective dose, perfusion parameter values and SNR. Group B:6 cases of chronic cerebral infarction patients, the patients with fixed tube voltage of 80 kv and two groups of tube current 150 and 80 ma cerebral perfusion,24 hours, the analysis method with group A.Results(1)Animal experiment: Effective dose of three groups of perfusion were 1.39, 0.87, 0.17 m Sv, 50 ma group compare with 80 ma group reduced about 37.41%, and 10 ma with 80 ma,reduced by 87.77%. Three groups perfusion parameters mean of CBF, CBV, MTT, 80 ma group compare with 50 ma group has no obvious statistical significance difference, 80 ma and 10 ma group, 50 ma and 10 ma, the difference was statistically significant. Three groups(CBF、CBV、MTT)SNR, respectively(13.39±3.50、10.18±2.39、10.55±2.13)、(12.89±6.29, 9.79±4.30、10.37±3.46)、(12.02±4.78, 9.07±3.39、9.19±4.23)(p<0.05) difference was statistically significant, comparison between group,80 ma and 50 ma group, there was no statistically significant difference(p>0.05). 80 ma and 10 ma, 50 ma and 10 ma group difference was statistically significant. Clinical trials, A group of three effective dose of the infusion were 3.37, 2.11, 1.79 m Sv, 100 ma fell 37.39% and 80 ma fell 46.88%.Three groups of scanning the perfusion parameters(CBF, CBV, MTT) between the mean difference was statistically significant(p < 0.05), the comparison between the two groups, 100 ma and 150 ma, no statistically significant difference,between groups150 ma and 80 ma,100ma and 80 mahas statistically difference(p < 0.05),Three groups of functional diagram(CBF, CBV, determined by MTT) SNR, respectively(4.61 ±0.45, 4.29 ± 0.59, 3.98±1.19),(4.41±1.07, 4.17±1.84, 4.09±2.21),(4.13 ±0.76, 3.89 ±1.57, 3.67± 1.94), 80 ma group was slightly lower in the 150 ma group,(p < 0.05) was statistically significant. Group B two perfusion with effective dose group A, perfusion parameters(CBF, CBV, MTT) difference between the mean with group A, functional diagram of the SNR, respectively(4.70 ±- 1.13, 4.16 ± 1.10, 4.12±1.45)(4.15 ±1.19, 3.79±2.06, 3.70±2.56).The results also experiment with A group.Conclusion From animal experiment indicated gem CT with ASIR weighting algorithm, can obviously reduce the infusion dose, namely low dose infusion, and does not affect image quality. Therefore, on the basis of the study on the feasibility of low-dose human brain perfusion, visible 80 k V/ 100 ma low-dose cerebral perfusion compared with standard perfusion imaging condition of 80 k V / 80 ma, effective dose reduce about 37.39%, perfusion parameter values and objective index SNR no difference.80 k V / 80 ma perfusion parameter values and SNR is standard slightly reduced perfusion results, although statistically significant, can be obviously found lesions, there was no evident difference subjective image quality score, still can meet the demands of clinical diagnosis, and prompt lesions. |
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