Changes in Pelvic Incidence, Pelvic Tilt, and Sacral Slope in Situations of Pelvic Rotation.

STUDY DESIGN: Digitally reconstructed radiograph-based study. OBJECTIVE: Using a computer-based method to determine what degree of pelvic rotation is acceptable for measuring the pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). The effectiveness of a geometrical formula used to calculate the angle of pelvic rotation proposed in a previous article was assessed. SUMMARY OF BACKGROUND DATA: It is unclear whether PI, PT, and SS are valid with pelvic rotation while acquiring a radiograph. MATERIALS AND METHODS: Ten 3-dimensionally reconstructed models were established with software and placed in a neutral orientation to orient all of the bones in a standing position. Next, 140 digitally reconstructed radiographs were obtained by rotating the models around the longitudinal axis of each pelvis in the software from 0 to 30 degrees at 2.5-degree intervals. PI, PT, and SS were measured. The rotation angle was considered to be acceptable when the change in the measured angle (compared with the "correct" position) was <6 degrees. The rotation angle (α) on the images was calculated by a geometrical formula. Consistency between the measured value and the set angle was assessed. RESULTS: The acceptable maximum angle of rotation for reliable measurements of PI was 17.5 degrees, and the changes in PT and SS were within an acceptable range (<6 degrees) when the pelvic rotation increased from 0 to 30 degrees. The effectiveness of the geometrical formula was shown by the consistency between the set and the calculated rotation angles of the pelvis (intraclass correlation coefficient=0.99). CONCLUSIONS: Our study provides insight into the influence of pelvic rotation on the PI, PT, and SS. PI changes with pelvic rotation. The acceptable maximum angle for reliable values of PI, PT, and SS was 17.5 degrees, and the rotation angle of the pelvis on a lateral spinopelvic radiograph can be calculated reliably.

[Applied research of CT angiography of lower extremities by using 100 kVp and iodixanol(270 mg I/ml) combined with iDose(4) iterative reconstruction technique].

OBJECTIVE: To evaluate the feasibility of CT angiography of lower extremities by using 100 kVp as tube voltage and Iodixanol(270 mg I/ml) as contrast medium combined with iDose(4) iterative reconstruction technique. METHODS: A total of 52 continuous patients with clinically suspected lesions of lower extremity arteries underwent CT angiography of lower extremities, divided into 2 groups, and different scan protocols were adopted. "double low" group included 26 patients using 100 kVp, Iodixanol (270 mg I/ml) and iDose(4) -4 iterative reconstruction algorithm; routine group included 26 patients using 120 kVp, Iopromide(370 mg I/ml) and filtered back projection reconstruction algorithm. The total amount of contrast medium in both groups was 95 ml. Artery CT value and background noise at the level of L4 vertebral, hip, knee and ankle were measured, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated, and the quality of images was evaluated subjectively. Scan length (L), volume CT dose index (CTDI(VOL)) and dose length product(DLP) were recorded, and the effective dose (ED) was calculated. The measurement results and subjective evaluation were analyzed statistically. CTA results were analyzed with the digital subtraction angiography (DSA) as the "gold standard". RESULTS: (1) No significant difference was existed in gender, age, height, weight and body mass index (BMI) of these two groups (P > 0.05). (2) No significant difference was existed in artery CT value, SNR and CNR at the level of L4 vertebral, hip, knee and ankle of the two groups (P > 0.05). Compared with routine group, background noise of "double low" group at the level of hip and knee increased by 16.6% and 13.8%, respectively (P < 0.05). (3) The image quality of the two groups met the requirement of diagnosis, no significant statistical difference was existed in subjective evaluation (P > 0.05). (4) The CTDI(VOL), DLP, ED of "double low" group were lower than that of routine group, with significant statistical difference (P < 0.05). The total amount of iodine in "double group" was lower than that of routine group (25.6 g vs 35.2 g). (5) A total of 7 cases from "double low" group underwent DSA examination, and 18 pathological changes (stenosis and occlusion) were found totally, in which 16 matched CTA; 6 cases from routine group underwent DSA examination, and 15 pathological changes (stenosis and occlusion) were found totally, in which 13 matched. CTA. No significant statistical difference was existed between the two groups in diagnostic efficacy (P = 0.626). CONCLUSIONS: Using 100 kVp and Iodixanol (270 mg I/ml) combined with iDose(4) -4 iterative reconstruction technique for CT angiography of lower extremities, the image quality could meet the requirement for clinical diagnosis, the radiation dose and the volume of contrast medium could be lowered.

A Computed Tomographic Morphometric Study of the Pediatric Occipital Bone Thickness: Implications for Pediatric Occipitocervical Fusion.

STUDY DESIGN: This study is a computed tomographic-based morphometric analysis of the pediatric occipital bones as related to pediatric occipitocervical fusion. OBJECTIVE: To quantify reference data concerning the thicknesses of the immature occipital bones to guide the pediatric occipitocervical fusion. SUMMARY OF BACKGROUND DATA: To the best of our knowledge, no published study has provided insight into the thicknesses of pediatric occiputs with different age groups. METHODS: 80 pediatric patients were divided into 4 age groups, and their occiputs were studied on Philips Brilliance 256 iCT scan. RESULTS: The mean thickness ± standard deviations of the pediatric occipital bones with different age groups is shown. The median and the paramedian regions are always thicker than the more lateral regions at each age group and the thickest point in the occiputs is mostly at the external occipital protuberance. The mean thickness of occiputs showed an obvious significant difference between each 2 age groups and no significant difference between male and female in different age groups except the group 4. CONCLUSION: Our investigation provides insight into the anatomy of occiputs in pediatric population and preoperative CT evaluation must be required to further decrease the risk of occipitocervical fusion.

[The study of removal methods on special type tracheobronchial foreign bodies].

OBJECTIVE: To investigate the available operation method of special type tracheobronchial foreign bodies removal. METHOD: Sixty one patients of special type tracheobronchial foreign bodies were extracted with some special instruments and methods depend on foreign body types. The features of operation on different kinds of foreign bodies were analyzed. RESULT: All patients were operated successfully by using foreign body hook (31 cases), pencil or writing screw brush extracted (11 cases), foreign body cage (13 cases), slender inverse claw esophagus foreign body clamp (3 cases) and so on. No complications and died cases were found. Only 5 patients were undertaken trachea incision before operation. CONCLUSION: Suitable instruments and technique chose for every individual cases is the key to successful operation.