ABSTRACT
BACKGROUND: Previous scholars often graded the height of iliac spine according to X-ray films. The quality of X-ray images is greatly affected by the photographic equipment and position. Simultaneously, X-ray film transforms the three-dimensional relationship between the iliac wing and the L5 pedicle into a planar relationship. The overlap of bone structure makes it difficult to identify anatomic markers. Especially, the combination with osteoporosis, calcification of paravertebral artery, and stasis of intestinal contents in the elderly will further affect the observation of bone structure on X-ray films. OBJECTIVE: To observe the degree of the entry point in L5 pedicle screw fixation shielded by the width and height of the iliac wing using the three-dimensional computed tomography reconstruction technique. METHODS: According to the inclusion and exclusion criteria, 350 CT images of L1-S2 region were selected as the study object. All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. The degree of the entry point in L5 pedicle screw fixation shielded by the width of the iliac wing in central axis layer of the horizontal axis was analyzed using the three-dimensional computed tomography reconstruction technique and divided into levels 0, I, II, and III. The degree of the entry point in L5 pedicle screw fixation shielded by the height of the iliac wing in central axis layer of the oblique sagittal plane was analyzed and also divided into levels 0, I, II, and III. Level 0 indicates that the entry point of L5 pedicle screw is not shielded by the iliac wing, and levels I, II, and III indicate increasing degrees of entry point of L5 pedicle screw shielding by the iliac wing. The difference in the effect of width and height of the iliac wing on the shielding degree of entry point in L5 pedicle screw was compared between males and females. RESULTS AND CONCLUSION: (1) In 80.0% of patients (280/350), the entry point of L5 pedicle screw was not shielded by the width of the iliac wing. In 20.0% (70/350) of patients, the entry point of L5 pedicle screw was shielded by the width of the iliac wing. In all, 27.3% (49/179) were male, including 27 with level I shielding, 14 with level II shielding, and 8 with level III shielding; 12.3% (21/171) were female, including 12 with level I shielding, 7 with level II shielding, and 2 with level III shielding. (2) In 80.6% (68/350) of patients, the entry point of L5 pedicle screw was not shielded by the height of the iliac wing. In 19.4% (68/350) of patients, the entry point of L5 pedicle screw was shielded by the height of the iliac wing. In all, 24.0% (43/179) of these patients were male, including 23 cases with level I shielding, 16 cases with level II shielding, and 4 with level III shielding; 14.6% (25/171) were female, including 13 with level I shielding, 8 with level II shielding, and 4 with level III shielding. (3) The degree of entry point of L5 pedicle screw shielding by the width of the iliac wing on the horizontal axis was not exactly the same as that of the height of the iliac wing on the sagittal axis of the L5 pedicle screw in the same patient. In this study, there were 70 patients with wide iliac wings and 68 patients with high iliac wings; the degrees of shielding by the width and height of the iliac wing were the same in 35 cases and different in 44 cases. (4) The degree of entry point of L5 pedicle screw shielding by the width and height of the iliac wing was greater in males than in females. (5) The results confirmed that the incidence of entry point of L5 pedicle screw shielding by the iliac wing width and height was 20.0% and 19.4%, respectively. The degree of entry point of L5 pedicle screw shielding by the width and height of the iliac wing was greater in males than females. The degree of entry point of L5 pedicle screw shielding by the iliac wing width along the horizontal axis was not completely consistent with that of L5 pedicle screw shielding on the oblique sagittal plane. It is of great significance to evaluate the relationship between iliac wing and L5 pedicle screw entry point by three-dimensional computed tomography reconstruction before operation for improving the safety of L5 pedicle screw placement and decision-making of operation.
ABSTRACT
The accurate position of the center of rotation (COR) is a key factor to ensure the quality of computed tomography (CT) reconstructed images. The classic cross-correlation matching algorithm can not satisfy the requirements of high-quality CT imaging when the projection angle is 0 and 180°, and thus needs to be improved and innovated. In this study, considering the symmetric characteristic of the 0° and flipped 180° projection data in sinogram, a novel COR correction algorithm based on the translation and match of the 0° and 180° projection data was proposed. The OTSU method was applied to reduce noise on the background, and the minimum offset of COR was quantified using the -norm, and then a precise COR was obtained for the image correction and reconstruction. The Sheep-Logan simulation model with random gradients and Gaussian noise and the real male SD rats samples which contained the heterogenous tooth image and the homogenous liver image, were adopted to verify the performance of the new algorithm and the cross-correlation matching algorithm. The results show that the proposed algorithm has better robustness and higher accuracy of the correction (when the sampled data is from 10% to 50% of the full projection data, the COR value can still be measured accurately using the proposed algorithm) with less computational burden compared with the cross-correlation matching algorithm, and it is able to significantly improve the quality of the reconstructed images.
ABSTRACT
Objective To investigate the effects of angle and length of lightwand in three-dimensional reconstruction images of the upper airway based on computed tomography.Methods A total of 245 patients,aged 18-86 years,were scanned by helical computed tomography in the head and neck.Reconstructed images,obtained by Aw4.4 Workstation,were printed out by the ratio of 1 ∶ 1.The tracheal tube was used to investigate the anatomic structure of the upper airway.The length L and angle α of the tracheal tube were recorded.And two distances (D1,D2) and one angle (β) were recorded:D1,the distance between the upper central incisor and root of epiglottis;D2,the distance between the root of epiglottis and midpoint of glottis;angle β,the angle of line D1 and D2.Results The oα value in male patients was significant higher than that in female patients:(70.02 ± 15.49)° vs.(55.84 ± 14.70)°.The β value in male patients was significant higher than that in female patients:(129.74 ± 14.82)° vs.(120.40 ± 14.19)°.The L value in male patients was significant higher than that in female patients:(12.80 ± 0.85) cm vs.(11.50 ± 0.65) cm.The D1 and D2value in male patients were significant higher than those in female patients:(7.53 ± 0.66) cm vs.(6.76 ± 0.53) cm,(3.13 ± 0.52) cm vs.(2.45 ± 0.32) cm.There were significant differences (P ＜ 0.05).The 245 patients were classified to 2 groups by using the function of hierarchical cluster analysis in the statistical software.The α value in group 2 was significant higher than that in group 1:(75.45 ± 9.53)° vs.(48.17 ± 9.29)°.The 3 value in group 2 was significant higher than that in group 1:(136.27 ± 9.86)° vs.(112.31 ± 8.64)°.The age in group 2 was significant higher than that in group 1:(53.92 ± 19.64) years vs.(36.93 ± 17.21) years.Correlation analysis showed that in 245 patients,angle α was positively correlated to angle β and age (P ＜ 0.05),and angle β was positively correlated to age (P ＜ 0.05).Conclusions The bent length and angle on lightwand can be affected by both the patients' gender and ages.
ABSTRACT
Objective To explore the clinical guiding value of spiral computed tomography(SCT)with three-dimensional computed tomography reconstruction(3-DCT)in percutaneous kyphoplasty(PKP).Methods 24 patients prepared to be treated with PKP were examined under 3-DCT before the treatment.Results According to the contra-indications shown by 3-DCT,11 patients' operation were cancelled;the others were treated with PKP and got good outcomes due to the accurate data provided by 3-DCT.Conclusion SCT plays an important role in PKP.