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Three-dimensional spiral CT measurement of atlantal pedicle and its clinical application.

ABSTRACT: The study aimed to establish the safe placement area and corresponding entry angle of atlantal pedicle screw using axial computed tomography (CT) measurement of atlas, in order to guide the clinical operation. Spiral thin-slice CT scan of atlas and three-dimensional reconstruction of 38 patients were randomly selected. Screw placement space was defined as the distance between the tangent lines of entry channel on the atlantal cross section and inner edge of transverse foramen and outer edge of spinal canal. Before operation, spiral CT measurement was used to determine the safe placement area, and the pipeline dredge method was used to conduct the internal fixation of atlantal pedicle screw for 7 patients. In CT measurements, the width of pedicle was 9.15±2.57 mm, which could safely accommodate screws with the diameter of 3.5 mm. The safe placement area was located in posterior arch of atlas (18.35±2.86 to 25.26±1.76 mm) away from the posterior tubercle, the entry angle ranged from 9.09±7.45° outward to 18.72±17.42° inward, and the length of screw channel ranged from 26.20±2.69 to 27.04±2.51 mm. The width of the safe placement area was up to 6.91±7.66 mm, and the angle of inclination on cross section was up to 27.81±10.32°. In conclusion, we identified a safe placement area for atlantal pedicle screw, where the screw was implanted inwards and outwards according to different entry points within the safe placement area. The detailed preoperative image measurement, determination of safe placement area and individual screw placement were found to be the key to a successful surgery.

SUBMITTER: Xie W

PROVIDER: S-EPMC5526069 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:BackgroundAlthough computed tomography (CT) with three-dimensional (3D) rendering of the calcaneus is used for diagnostic evaluation of disorders, morphological measurements for the calcaneus are mostly based on a two-dimensional plane. The purposes of this study were to design a method for 3D morphological measurements of the normal calcaneus based on CT post-processing techniques, to measure morphological parameters in the male and female groups and describe gender differences of the parameters, and to investigate the reliability of such measurements.MethodsOne hundred and seventy-nine patients (83 men and 96 women) with a mean age of 40.6 (range, 21 to 59) years who underwent CT scans for their feet were reviewed retrospectively. The 3D structure of a normal calcaneus after shaded surface display reconstruction was extracted by interactive and automatic segmentation. Morphological measurements were achieved by means of a 3D measurement method based on CT image post-processing. Lengths and heights of the main parts of the calcaneus, Gissane's angle, Böhler's angle and the area of articular facet were worked out in 3D space. Gender-related size differences of parameters were compared using analysis of covariance (ANCOVA), adjusting for body height. Intra-observer and inter-observer reliabilities were assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for precision study.ResultsA large range of measurement values was found. Only the length of the anterior process was without gender difference (p?>?0.05). The other parameters in the male group were greater than those in the female group (p?<?0.01 for each, ANCOVA). All parameters had excellent reliability and reproducibility (ICC?>?0.8). Precision was acceptable for intra-observer RMS-SD (linear, angular and areal measurements no more than 0.6 mm, 1.2° and 0.25 mm2, respectively). Inter-observer RMS-SD ranged from 0.4 to 1.6 mm for linear measurements, 1.2 to 2.5° for angles and 0.24 to 0.40 mm2 for areas.ConclusionsThree-dimensional morphological measurement based on a CT post-processing technique was highly reliable and repeatable for calcaneal anatomic morphological measurement. The current data will be helpful for anatomic reduction of calcaneal fractures and calcaneal malunion.

Project description:BackgroundThe volume and thickness of intravesical prostatic protrusion and other characteristics of benign prostatic hyperplasia have not been investigated. We determine the effects of age and prostate volume on anatomical features of benign prostatic hyperplasia using three-dimensional measurement in this study.MethodsThis retrospective study included a total of 98 patients with benign prostatic hyperplasia. Three-dimensional models of prostate, central gland, peripheral zone, intravesical prostatic protrusion, prostatic urethra and bladder were reconstructed according to pelvic T2-weighted magnetic resonance imaging of these patients. The models were used to measure the intravesical prostatic protrusion volume, intravesical prostatic protrusion thickness, intravesical prostatic protrusion index, intravesical prostatic protrusion, prostate volume, peripheral zone volume, peripheral zone thickness, peripheral zone index, prostatic urethra thickness, the angle and distance of distal prostatic urethra with regard to coronal plane and sagittal plane and so on.ResultsIntravesical prostatic protrusion volume, intravesical prostatic protrusion thickness and peripheral zone volume of prostate volume >80 mL group were significantly higher than these in prostate volume <80 mL group (P<0.001, 0.01, 0.01, respectively). These parameters significantly increased with age (P<0.001, 0.01, 0.05, respectively). Peripheral zone index was significantly lower of prostate volume >80 mL group than these in prostate volume <80 mL group (P<0.05). Peripheral zone index significantly decreased with age (P<0.01). Intravesical prostatic protrusion index had no significant difference in all age groups. Peripheral zone thickness and prostatic urethra thickness had no significant difference in all groups. The distance and angle of distal prostatic urethra prostatic urethra with regard to coronal plane were significantly higher than these with regard to sagittal plane (both P<0.001).ConclusionsThe rearward slope of the prostatic urethra is greater than the left or right offset during the process of benign prostatic hyperplasia. Three-dimensional measurement provides good supports for further clinical and scientific research.

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Three-dimensional spiral CT measurement of atlantal pedicle and its clinical application.

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