ABSTRACT
Objective To preliminarily investigate the optimum scheme of thyroid CT flat scanning plan,to reduce the artifacts and the radiation dosage.Methods Patients who were involved in this research with thyroid CT flat scanning were divided into three groups:group A (conventional scan group),group B (dosage- reduced group)and group C (a combination of body posture change and dosage reduction).In group A (50 patients),the patients’bilateral arms were naturally drooped on both sides of the body during scanning (scan parameters:120 kV,250 mA).In group B (50 patients),the patients were scanned under the same circumstance with group A,but difference in scanning condition (scan parameters:100 kV,280 mA).In group C (50 patients),the patients kept one arm rise upward,another arm reach firmly toward the contralateral iliac bone during CT scan(scan parameters:100 kV,250 mA).CT attenuations,noise and SNR values around the soft tissue of thyroid gland,which was in the most severe thyroid artifacts (seventh cervical vertebrae to the first thoracic vertebrae level),were measured among the three groups.Meanwhile,the patient’s dose length product (DLP)and effective dosage (ED)were calculated.The images of the three groups were measured by double-blind method,i.e. severe artifacts,moderate artifacts,mild artifacts,and no artifacts.Results The image quality in group C was significantly higher than that of group A and group B (P＜0.05).There was no difference in subj ective quality between group A and group B (P＞0.05).The CT and noise values of group C were better than those of group A and group B (P＜0.05),while the radiation dosage was lower than that of group A and group B (P＜0.05).Conclusion When the thyroid CT scan is performed with the unilateral limb lifting and the other arm extending to the contralateral iliac bone,the thyroid band artifacts can be effectively reduced and decreasing the kV can reduce the radiation dosage.
ABSTRACT
ObjectiveTo recognize the normal CT appearances of adult pterygoid hamulus and increase the ability to recognize pterygoid hamulus abnormalities.Methods The pterygoid hamulus of 108 normal adults ( male:53 cases,female,55 cases) were studied with MIP and VR reconstructive images by 64-slice spiral CT in order to observe its normal shape,to measure its length,diameter,vertical height,horizontal width,abduct angle in coronal position and post-abducent angle in anteroposterior position.The differences between genders,two sides and age groups were compared,respectively.ResultsThe normal pterygoid hamulus had a wide basal body and a pillar caudomedial part with round or intumescentia extreme.In coronal position,the distal end towards outer direction in 214 sides and 2 sides in inner direction. In anteroposterior position,the distal end towards posterior direction in 190 sides and anterior direction in 26 sides.The pterygoid hamulus length,vertical height,and horizontal width of adult males were (8.18 ± 0.94) mm,(7.23 ±0.92) mm,(4.27 ±0.81 ) mm,respectively.They were larger than the adult females (7.31 ± 1.01) mm,(6.26 ±0.90) mm,(3.97 ±0.82) mm,and the difference was statistically significant (t values were 6.56,7.86,2.72 respectively,P ＜ 0.05).The pterygoid hamulus vertical height of age group over 60 years old (7.13 ± 1.35) mm exceeded the age groups of 18-39 (6.55 ±0.86) mm.The difference was statistically significant ( F =4.95,P ＜ 0.05 ).Conclusions64-slice spiral CT could display the shape,length and angle of pterygoid hamulus in full. It could help to recognize correlated pterygoid hamulus diseases.
ABSTRACT
Objective To muhi-directionally visualize and measure the normal anatomy of palatovaginal canal and its communications with high-resolution multi-slice spiral CT and its post-processing technologies.Methods One hundred and sixty-seven subjects with normal PPF and its communications were examined by 16-MSCT using high-resolution technique.The MPR and CPR images of palatovaginal canal were obtained on postproeessing workstation.The length and diameter of the palatovaginal canal and its communications was measured and analyzed with one way ANOVA analysis and independent samples t test.Results In this study, the detection rate of palatovaginal canal on 167 subjects was 98.8% (330/334).The mean length of left and right palatovaginal canal was (1.18 ± 0.22) cm and (1.07 ± 0.29) cm, respectively.The mean diameter of anterior opening (0.19±0.06)cm was significantly larger than median (0.10 ± 0.04) cm and posterior opening (0.16 ± 0.07)cm in left palatovaginal canal (F = 211.109, P < 0.01).Similarly,The mean diameters of anterior, median and posterior opening in right palatovaginal canal were (0.19±0.06)cm, (0.10±0.03)cm and(0.16±0.06) cm, respectively (F = 139.350,P <0.01).No significant difference on length measurements was revealed between the men [left: (1.18±0.22) cm; right: (1.12 ± 0.31)cm] and women [left: (1.07±0.25)cm; fight: (1.02±0.25)cm] (left: t = 0.919, P > 0.05 ;right:t = 1.117,P > 0.05).Between the men [left: (0.19±0.06) cm, (0.10 +0.04) cm and (0.16±0.07) cm; right: (0.19±0.06) cm,(0.10±0.04) cm,(0.16±0.06) cm] and women [left: (0.20±0.08) cm, (0.10±0.04) cm and (0.15±0.05) cm; right: (0.20±0.06) cm, (0.09± 0.04) cm and (0.15±0.05) cm], no significant difference on diameter measurements was revealed (left: t =- 1.183,0.190 and 1.660 ; fight: t = - 1.420,1.210 and 0.802 ; all P > 0.05).Conclusion On the basis of high-resolution MDCT scan, MPR and CPR images could visualize clearly the morphologic features of the palatovaginal canal, which may be helpful for making diagnostic and therapeutic decisions because more imaging information could be obtained.