Objective To study the manual control respiratory rhythm trigger acquisition (MCRRTA)technology in improving image quality and shortening acquisition time of the low-field MRCP scan.Methods 40 patients underwent MRCP scans using both automatic respiratory rhythm trigger acquisition (ARRTA)and MCRRTA,and the acquisition time and image quality were also ana-lyzed.Results The acquisition time of MRCP using ARRTA and MCRRTA were 675.13 ± 35.89 s and 546.38 ± 30.61 s respec-tively,exhibiting significant differences using the paired sample t-test (t=13.85,P=0.000).In ARRTA group,the scores of the image quality were 4 in 11 cases (11/40,27.5%);3 in 18 cases (18/40,45.0%);2 in 10 cases (10/40,25.0%);and 1 in only 1 case (1/40,2.5%),respectively.In MCRRTA group,the scores of the image quality were 4 in 25 cases (25/40,65.5%);3 in 10 cases (10/40,25.0%);2 in 5 cases (5/40,12.5%);and no case with 1 score (0/40,0%),respectively.The differences in image quality between two groups were statistically significant using the wilcoxon rank sum test (Z=-3.036,P=0.002).Conclusion MCRRTA technology in low-field MRCP scans can improve significantly image quality and shorten examination time.

Objective To study the CT features of nasal bone foramen and nasal bone fracture,and investigate the differential key points of them.Methods visual observation was performed for 30 selected skull specimens of adults(60 nasal bones)(specimens group),then CT imaging was obtained for them with volume redering(VR)reconstruction(imaging group).The frequency of the nasal bone foramens,their size,shape and location were statistical analysed.Ferthermore,CT features of nasal bone foramen and nasal bone fracture were analyzed in 30 patients who were suspected having nasal bone fractures by clinicians.Results Forty foramen shape nasal bone foramens were found in observation group,while 37 were obtained in imaging group.For patients,19 cases were diagnosed as single fracture of nasal bone by non-spiral axial high-resolution CT images.When using both axial and multi-plane reformation(MPR)and VR images,8 of 19 cases were diagnosed as single fracture,5 were multiple fractures,4 were normal nasal bone foramen,and 2 were normal variation.The other 11 cases that were diagnosed as multiple fractures by non-spiral axial HRCT images were demonstrated as 6 cases multiple fractures and 5 single fracture by combining axial images with MPR and VR images.The frequencies of foramen shape nasal bone foramen in specimens group and imaging group were 66.7% and 61.7%,respectively,and there were no significant differences between them(χ2=1.33,P＞0.05).Conclusion The nasal bone foramen is the normal anatomy,and to recognize the imaging findings of it can improve the diagnostic accuracy of nasal bone fracture.