Accuracy of cone beam computed tomography in determining the location of the genial tubercle.

OBJECTIVE: To determine the accuracy of cone beam computed tomography (CT) to predict the location of the genial tubercle. STUDY DESIGN AND SETTING: Cadaver study for anatomic analysis of 17 adult human cadaver heads. Each skull/cadaver head underwent radiographic imaging with cone beam CT and cadaver dissection. Measurements, including mandibular height (MH), genial tubercle width (GTW), genial tubercle height (GTH), distance from inferior border of mandible to genial tubercle (IBM/GT), and mandibular thickness (MT) were recorded. RESULTS: Statistical analysis with paired t test showed no significant difference between cadaver dissections versus cone beam measurements. Ninety-five percent confidence intervals (CI) were as follows: GTW (-0.2 to 1.0), GTH (-0.1 to 0.9), distance IBM/GT (-0.8 to 5.0), MH (-1.3 to -2.6), and MT (-0.1 to 0.3). CONCLUSION: These results show the accuracy of the 3D cone beam CT in the anatomic location of the genial tubercle. SIGNIFICANCE: This radiographic technique may prove useful in pre-operative planning for the mandibular osteotomy in genioglossus advancement procedures.     

CT analysis of hindfoot alignment in chronic lateral ankle instability

A prospective case-control study was performed comparing axial and coronal CT scan images of 11 patients (14 ankles) with chronic lateral instability and 12 controls. Scans were performed in a standardized fashion to simulate weight-bearing. Nine measurements to evaluate the alignment of the hindfoot and forefoot were made on two occasions by two observers. The blinded images were read in order of assigned random number. The angle between the calcaneus and the vertical plane showed a statistically significant difference between patients (6.4 +/- 4 degrees varus from vertical) and controls (2.7 +/- 5 degrees) using unpaired ANOVA (p < 0.01). Intra-observer (R2 = 0.49 +/- 0.19) and interobserver (R2 = 0.71 +/- 0.13) variation showed moderate reliability across all measurements. This study demonstrates a method to evaluate hindfoot varus on CT scan. Many factors have been studied (e.g., proprioception) as the cause for recurrent instability, and this is the first time, to our knowledge, that an anatomic cause has been demonstrated. Although calcaneal osteotomy is clearly not indicated routinely, it may have a role in correcting extreme varus, which may contribute to failed ligament reconstruction in patients with ankle instability.     

经皮椎板关节突螺钉固定的应用解剖及影像学研究

[目的]为经皮椎板关节突螺钉的器械设计及临床应用提供解剖学依据。[方法]利用30例干燥腰椎标本，用游标卡尺及量角器测量腰椎椎板上缘及下缘的厚度，椎板关节突螺钉的长度。通过影像学测量椎板的内倾角和下倾角。[结果]椎板的上缘薄而下缘厚。从L1～5椎板的厚度、螺钉的长度及从内倾角逐渐增加，而下倾角逐渐减小。[结论]上缘的厚度太薄不适合螺钉的放置。从L1～5使用4．5mm的皮质骨螺钉固定是安全的，但应该在椎板的下缘置人。注意下倾角和内倾角的变化。设计的瞄准器应该具有调节角度的装置。     

Transethmoidal approach to the optic canal: surgical and radiological microanatomy

BACKGROUND: The purpose of the study is to describe anatomic topographic landmarks for transethmoidal approach to optic canal for optic nerve decompression. The study focuses on microsurgical/radiologic anatomies and their relationships in the region of the optic canal and orbit. METHODS: Human optic canal and related anatomic structures were studied in orbits of 6 formalin preserved adult human cadavers. In addition, anatomic measurements were made with digital vernier caliper on the orbits of 25 adult human skulls. The relation between ethmoidal and sinus was assessed with computed tomography (CT) scan in 25 living human heads needing cranial CT scan for any reason. RESULTS: The suture on the conjunction of frontal, maxilla, and lacrimal bones with a location in medial side of the orbit was accepted as a landmark. When the measurements were taken from this landmark, the distances to supraorbital margin were: right(R): 16.76 +/- 2.62 mm, left (L): 17.10 +/- 1.97 mm, and to infraorbital margin were R: 20.18 +/- 3.24 mm, L: 18.94 +/- 2.19 mm. The distances to the anterior ethmoidal foramen were R: 19.66 +/- 3.96 mm, L: 19.11 +/- 2.84 mm, and to the posterior ethmoidal foramen were R: 32.01 +/- 2.90 mm, L: 32.62 +/- 3.33 mm. Mean distance between the anterior and posterior ethmoidal foramen were R: 12.55 +/- 3.4 mm, L: 13.51 +/- 4.2 mm. The posterior ethmoidal foramen and optic ring were separated only by the mean distances of R: 5.34 +/- 2.81 mm, L: 4.9 +/- 3.35 mm. The distance from the suture to the distal (orbital) opening of the optic canal was R: 37.35 +/- 2.73 mm, L: 37.52 +/- 3.47 mm and to proximal (intracranial) opening of the canal were R: 49.52 +/- 2.62 mm, L: 50.94 +/- 3.35 mm. The average widths of proximal (intracranial) canal measured were R: 7.43 +/- 1.95 mm, L: 7.38 +/- 2.01 mm and those of distal canal (orbital) were R: 5.12 +/- 1.1 mm, L: 4.95 +/- 1.32 mm. The mean lengths of the optic canal were R: 11.19 +/- 2.68 mm, L: 12.42 +/- 3.38 mm. In radiologic examinations, the mean numbers of anterior group ethmoidal cells were R: 7, L: 6 and those of posterior group ethmoidal cells were R: 4, L: 3. The results of CT demonstrated 7 (14%) Onodi or sphenoethmoidal cells in 50 orbits of living humans. CONCLUSION: The examination of radiologic anatomy in addition to microanatomy can significantly contribute to preoperative and postoperative evaluation of the patients.     

Measurements of acetabular cup position and pelvic spatial orientation after total hip arthroplasty using computed tomography/radiography matching.

This study presents a clinical validation of postoperative measurements of acetabular cup alignment following total hip arthroplasty (THA). The methodology was based on concurrent anatomic three-dimensional (3D) measurements of both the acetabular cup alignment and pelvic orientation, using an original CT/X-ray matching algorithm named Xalign. The subjects were 19 patients who had undergone bilateral THA using CT-based surgical navigation. All patients had postoperative pelvic CT scans and multiple antero-posterior (AP) pelvic X-rays. Using a proprietary software algorithm, the X-rays included in the study were matched with the corresponding postoperative CT scans. The goal of this method was to allow 3D anatomic pelvic and acetabular measurements on two-dimensional AP X-rays. The postoperative cup abduction, version and pelvic flexion angles were determined in three different ways: using CT images directly, applying the Xalign method, and finally by performing conventional (abduction only) measurements on AP pelvic X-rays. The cup orientation measured on CT images was taken as the ground truth. The Xalign measurement errors were defined as the difference between the CT cup values and those obtained by applying the matching method. The mean cup abduction error was 0.85 degrees +/- 1.3 degrees (+/- standard deviation) and the mean version error was 0.01 degrees +/- 1.99 degrees . Conventionally measured cup abduction ranged from 44 degrees to 62 degrees and correlated significantly (p = 0.001, r = -0.5) with pelvic flexion angle, proving the linear negative correlation between pelvic flexion and the error in conventional radiographic cup measurements. The Xalign method offered reasonable accuracy for cup orientation, and allowed cup and pelvic 3D anatomic measurements at different times.     

下颈椎椎弓根螺钉内固定相关参数的解剖学和影像学测量

目的:测量成人下颈椎椎弓根相关径线,为临床应用下颈椎椎弓根螺钉内固定提供相关解剖参数.方法:成人干燥尸体颈椎C3～C7标本20具,分别用手工和CT测量椎弓根宽度、高度,从横断面CT图像上测量椎弓根的内部宽度、内部高度,从纵断面CT图像上测量椎弓根矢状角.随机在CT窒保存的100例成人患者的颈椎CT图像上测量椎弓根的宽度、自身长度和椎弓根通道全长、椎弓根内倾角.结果:下颈椎标本各节段椎弓根宽度、高度的手工测量值与CT测量值比较无统计学差异(P>0.05),椎弓根宽度小于高度;C3～C6节段CT测量椎弓根内部宽度平均为2.5～2.8mm,椎弓根内部高度平均为2.9～3.0mm,C7椎弓根的内部宽度和高度接近,约4.0mm;下颈椎标本CT测量椎弓根矢状角分别为C3 8.6°,C4 4.6°,C5-1.3.,C6-4.0°,C7-8.2°.100例成人下颈椎CT图像测量椎弓根宽度最小值为3.1mm(C3),最大值为9.3mm(C7),其中>3.5mm者为92.8%;椎弓根自身长度平均为19.1～20.5mm,椎弓根通道全长平均为33.2～35.0mm,椎弓根内倾角平均值C3～C5为43.2°～45.1°,C6为40.8°,C7为37.5°.结论:术前CT测量可为椎弓根准确置钉提供可靠的解剖参数,下颈椎椎弓根一般可接受直径3.5mm的螺钉同定.     

Variability of maximal aortic aneurysm diameter measurements on CT scan: significance and methods to minimize

OBJECTIVES: We noted substantial differences when measuring repeatedly the same abdominal aortic aneurysm (AAA) on the same computed tomography (CT) scan. This study quantitated this variability, and methods to minimize it were developed. METHODS: The CT maximal diameter of 25 AAAs was measured by eight experienced observers, including six vascular surgeons and two radiologists, using two methods: an unstandardized protocol, and a standardized protocol using fine calipers to carefully measure the largest diameter perpendicular to the estimated aneurysm centerline, from outer aneurysm wall to outer wall. The average measurement difference between observers was calculated for each method. The average difference between each observer's measurement and the official radiology report value was also calculated. Agreement between the two measurement methods was assessed with Bland-Altman plots. RESULTS: The difference in maximal diameter measurements between each observer averaged 4.0 +/- 5.1 mm (range, 0.0-35.0 mm) with the unstandardized method. The mean measurement difference with the standardized protocol was significantly lower, and averaged 2.8 +/- 4.4 mm (range, 0.0-26.0 mm; P<.05). Measurements taken from the official radiology report differed from each of the observer's standardized measurement by an average of 5.0 +/- 6.3 mm (range, 0.0-28.0 mm). This difference was similar for both the unstandardized and standardized methods. Bland-Altman plots confirmed the wide variation of the maximal diameter measurements when the unstandardized method was compared with the standardized method (95% confidence interval, -9-9 mm). CONCLUSIONS: Routine CT maximal diameter measurement of AAAs can have substantial interobserver variability. Standardized measurement protocols can decrease, but not eliminate, this measurement variability. Thus apparent size changes based on CT measurements may represent measurement artifact rather than actual aneurysm growth or shrinkage, particularly when a standardized system is not used.     

Modified Technique of Chin Augmentation With MEDPOR for Asian Patients

Background: Commonly used chin implants are made of silicone, expanded polytetrafluoroethylene (e-PTFE), or high-density porous polyethylene (MEDPOR). Although MEDPOR is an effective implant for chin augmentation, modification of the external aspect of the implant is recommended, particularly for Asian patients, to create an appropriate shape for the new chin. It is often difficult to contour the inner aspect of the implant to conform to the patient's mandible. Without modification, a gap may exist between the implant and mandible. To address this problem, a modified augmentation technique was developed. Objectives: The authors describe their modified technique for MEDPOR chin augmentation, which includes removal of the genial tubercles and, if necessary, the mental protuberance. Methods: Ninety-five patients underwent the modified MEDPOR technique of chin augmentation. Before placement of the contoured implant, a drill was used to remove the patient's genial tubercles. If the mental protuberance was deemed too prominent, it was removed as well. The implant was inserted and fixed to the mandible with 2 titanium screws. Results: Results were satisfactory in 90 cases. Chin shape was too "strong" in 4 patients, and another patient had poor transition between the implant and mandible. Complications were minimal. The most common complication in this modified technique was lower lip numbness, which was transient in all cases. Conclusions: The MEDPOR chin implant can be effectively contoured to the mandible by removing the genial tubercle and/or mental protuberance. This technique is less invasive than chin osteotomy. Successful results can be achieved with minimal risks. Level of Evidence: 4.     

脊柱截骨术治疗创伤僵硬性胸腰段后凸畸形的解剖与临床研究

目的探讨经椎弓根椎体楔形截骨术治疗创伤僵硬性胸腰段后凸畸形的安全性和有效性。方法解剖研究中将16具新鲜胸腰段脊柱标本按不同脊柱截骨术分为3组,A组：脊柱开放-闭合截骨术,B组：经椎弓根椎体楔形截骨术,C组：改良经椎弓根椎体楔形截骨术（截骨包括上位椎间盘后半部分）。测量截骨前后Cobb角的变化、椎体高度和椎体前缘高度的变化。临床研究中共26例患者,其中男性18例,女性8例,平均36岁。受伤至本次手术时间3个月～11年,平均25个月。入院前治疗包括非手术治疗9例,手术治疗17例。神经损伤程度按照Frankel分级：A级10例,B级2例,C级10例,D级2例,E级2例。本组病例均有不同程度的腰背部疼痛,VAS评分平均4．5分（2．5～6．0分）。后凸角20°～75°,平均35°。根据后凸角大小选择行后路经椎弓根椎体楔形截骨术或改良椎体楔形截骨术。结果解剖研究胸腰段标本中A组平均纠正（38．0±2．5）°,B组（36．0±3．6）°,C组（49．0±2．0）°。A组椎体高度平均增加（13．8±1．4）mm,椎体前缘增加（30．2±2．5）mm,而B、C组椎体高度平均短缩（2．8±0．8）mm和（3．8±0．7）mm,前缘增加（25．0±1．2）mm和（2．2±0．9）mm。临床研究患者均获随访,随访时间10个月～6年,平均12．5个月,患者获得满意减压和后凸畸形矫正,术后后凸角度平均为10．8°（0°～40°）,脊柱后凸畸形平均矫正24°。50％患者的神经功能得到了不同程度恢复,全瘫患者恢复率为30％,主要是感觉功能恢复,而不全瘫患者的恢复率为64．3％,感觉和运动功能均有恢复。腰背部疼痛有不同程度好转,VAS评分平均2．3分（1．0～3．5分）。结论创伤僵硬性胸腰段后凸畸形患者可以选择经椎弓根椎体楔形截骨术或改良经椎弓根椎体楔形截骨术。术后可获得满意的减压效果和后凸畸形纠正,神经功能有不同程度恢复,腰背部疼痛有不同程度好转。     

Cup alignment error model for total hip arthroplasty

Almost all computer-assisted orthopaedic surgery systems that rely on the anterior pelvic plane definition, such as in computed tomography and magnetic resonance image-based, fluoroscopy-based, and nonimage total hip replacement approaches, are derived from identifying two pairs of pelvic bony landmarks: anterior superior iliac spines and the pubic tubercles. Although these systems strive to achieve cup alignment accuracy of approximately 1 degree, even a minor failure to correctly identify these anatomic landmarks can lead to higher inaccuracies in the final cup alignment. This study shows how to examine the effects of these inaccuracies on the final acetabular cup implant orientation during total hip replacement by generating a kinematic model, which then is simulated. Simulation results indicate that, for example, a total error of 4 mm in measuring the anterior superior iliac spine and the pubic tubercles would result in a final cup orientation of 47 degrees and 27 degrees in abduction and version respectively, resulting in a 2 degrees abduction error and 7 degrees error in version when targeting 45 degrees abduction and 20 degrees version results. These calculations can be repeated for any error values.     

内窥镜鱼尾纹除皱术的颞额区应用解剖学

在开展内窥镜眼角鱼尾纹除皱术中减少面神经颞支损伤的概率。方法 在３６侧成人头部标本上，探讨颞额区层次特点及其面神经颞支的定位。结果 面神经颞支位于颞浅筋膜和额肌的深层，通常有１－４分支，第１支先位于关节结节前方８．１±２．１ｍｍ，然后向内上方于走进入额肌或眼轮匝肌上部，位于骨性眼外毗外毗上方３３．８±４．９ｍｍ。     

Computed tomography in the determination of transarticular C1-C2 screw length

This study evaluated the significance of computed tomographic (CT) measurements of the upper cervical vertebrae and their clinical implications in transarticular C1-C2 screw placement. In the first part of the study, analysis of axial CT scans of the atlas of 46 patients who had a normal C1-C2 region was performed. Measurements included the vertical distance between the middle of the ventral cortex of the lateral mass and the anterior-most point of the anterior tubercle, and the angle of the anterior ring of C1 relative to the frontal plane. In the second part, axial CT scans of the upper cervical spine were performed in seven cadaveric cervical spines and analyzed using the same criteria. Using the Magerl technique of transarticular C1-C2 screw placement, one screw was placed in each cervical spine. Following each placement, a strict lateral radiograph was taken and the distance between the tip of the screw and the anterior-most point of the anterior tubercle of C1 was measured. Analysis of the cervical cadaveric specimens showed the vertical distance between the middle of the ventral cortex and the anterior-most part of the anterior tubercle when measured on CT scan corresponded to the distance measured on lateral radiographs after placement of the C1-C2 transarticular screw. The study of the 46 patients with normal C1-C2 region had shown the mean values of linear and angular measurements to be greater in males than in females, although no significant difference was found between the two groups (P>.05). The mean distance between the anterior-most point of the anterior tubercle and the middle of the ventral cortex of the lateral mass was 6.5+/-1 mm, and the mean transverse angle of the anterior ring relative to the frontal plane was 22 degrees+/-3.1 degrees. Axial CT evaluation of the individual anatomic relationships of the atlas is simple and may be a useful guide in the determination of the length of the transarticular screw when performed during surgery under lateral fluoroscopic control.     

应用影像归档和通信系统测量成人下颈椎关节突关节的临床意义

目的通过影像归档和通信系统(PACS)测量成人下颈椎关节突关节解剖参数,并探讨其临床意义。方法选择2014年9月—2015年2月本院63例成年门诊患者,行颈椎CT检查,所得数据传输至PACS,然后在Aquarius NET Viewer(V4.4.6.80)窗口界面手工进行颈椎关节突关节各参数的测量分析。所得数据纳入统计学分析,比较同一关节突关节左右侧的差异以及男女间的差异。结果成年人下颈椎同一关节突关节的左右两侧横径、矢状径及外斜径差异无统计学意义,成年人下颈椎双侧关节突关节基本对称。男性下颈椎不同关节突关节面的矢状径为11~13 mm,外斜径为11~12 mm;女性矢状径为10~12 mm,外斜径为10~11 mm,男性下颈椎关节突关节明显大于女性。结论 PACS测量成人下关节突关节解剖参数具有较高的一致性,对颈椎后路置钉融合手术中侧块螺钉的选择具有参考意义。按Magerl或Anderson方法置入下颈椎侧块螺钉时,男性选择长12~14 mm的螺钉是安全的,而对于女性则建议选择长12 mm的侧块螺钉。     

Stereotactic imaging quality assurance using an anthropomorphic phantom.

OBJECTIVE: A custom-designed anthropomorphic head phantom, containing computed tomography (CT) and magnetic resonance (MR) viewable targets, was used in the assessment of stereotactic localization accuracy. MATERIALS AND METHODS: The Brown-Roberts-Wells (BRW) or Leksell stereotactic ring was rigidly fixed to the phantom. CT and MR images were then obtained according to radiosurgery protocols with the corresponding localizer frame attached. Plastic spheres and rods appeared at various locations within the phantom, when filled with aqueous solution, and their images served as targets to compute stereotactic target coordinates using software compatible with each frame. Coordinates derived using CT and MR were compared with mechanical measurements obtained using the BRW or Leksell stereotactic arc systems. RESULTS: For the BRW stereotactic system, the average vector distance to agreement of image-derived coordinates with the mechanical measurements was 1.41 +/- 0.90 mm (CT) and 1.37 +/- 0.38 mm (MR). Similar results were obtained using the Leksell system: 0.78 +/- 0.33 mm (CT) and 1.45 +/- 0.86 mm (MR). The vector distance to agreement between CT and MR was 1.42 +/- 0.55 mm for the BRW and 1.31 +/- 0.60 mm for the Leksell systems. CONCLUSIONS: The data support the use of our anthropomorphic phantom, and present a methodology for assessing radiosurgery target localization and imaging accuracy.     

Morphologic evaluation of cervical spine anatomy with computed tomography: anterior cervical plate fixation considerations

The computed tomography (CT) studies of the cervical spine from 50 males and 50 females were reviewed to provide morphometric data on a variety of anatomic parameters relevant to anterior cervical reconstruction and fixation. Measurements were made of the vertebral body width and midsagittal anteroposterior (AP) diameter and the distance between the medial borders of the longus coli muscles. Distances between adjacent endplates were also measured, both at their midpoint and at the anterior margin. Widths of the vertebral bodies measure 24.6 +/- 2.4 and 23.0 +/- 2.4 mm in males and females, respectively, with the narrowest measuring 17 and 14, respectively. The average midsagittal AP diameter of each vertebral body in males was approximately 17-18 mm, with the smallest AP diameter measured to be 13 mm. The average midsagittal AP diameter of each vertebral body in females was approximately 15-16 mm, with the smallest being 10 mm. CT scanning provides excellent osseous detail for the measurement of such parameters, and with its widespread use in the evaluation of cervical disorders, large numbers of patients can be reviewed.     

Intraoperative technique to define the safe lateral limits of anterior cervical corpectomy: a cadaveric study

STUDY DESIGN: We describe a surgical radiographic technique during anterior cervical corpectomy to define the safe lateral limit of dissection. OBJECTIVE: To assess the radiographic technique accuracy using computed tomography (CT) measurements on cadaveric specimens. Two clinical cases are presented. SUMMARY OF BACKGROUND DATA: During anterior cervical surgery loss of orientation can lead to eccentric decompression and vertebral artery injury. METHODS: A two-level corpectomy on 4 cadaveric samples was filled with radioopaque dye. An "introperative" antero-posterior x-ray was used to measure the narrowest distance from dye column to uncovertebral joints. A CT scan confirmed the distance from corpectomy to vertebral arteries. RESULTS: The distance between the x-ray dye column and uncovertebral joints averaged 2.7 mm (range, 0 to 7+/-2.2 mm). A CT scan demonstrated the distance from corpectomy to vertebral artery averaged 4.5 mm (range, 0 to 10+/-4.4 mm). The measured distance underestimated the true distance by an average of 1.8 mm (range, 0 to 8+/-2.2 mm). CONCLUSION: An intraoperative radiographic technique can estimate the lateral distance between the corpectomy and vertebral arteries by measuring the distance from the dye column to uncovertebral joints. The dye radiographic technique provides the surgeon an additional margin of safety.     

Application accuracy of an electromagnetic field-based image-guided navigation system

OBJECTIVE: We tested the application accuracy of an electromagnetic field-based image guidance system to compare it to traditional optically tracked systems. METHODS: A plastic skull phantom was fitted with fiducial markers rigidly attached via self-drilling bone screws. Volumetric CT scan was obtained to simulate the clinical condition. A metal disc marked in 1-mm increments was placed at the expected target point. Following registration and alignment of a trajectory guide, radial and depth localization errors were measured after both freehand and stabilized approaches on both the right and left sides. Statistical analyses of the localization errors were performed. RESULTS: Total target localization error ranged from 0.71 to 3.51 mm with a mean +/- SEM of 2.13 +/- 0.11 mm. The radial error averaged 0.98 +/- 0.11 mm, depth error 1.74 +/- 0.13 mm. The freehand procedures produced a statistically greater radial, depth and total error than the fixed procedures. CONCLUSIONS: Accuracy of image-guided localization using an electromagnetic field guidance system is similar to that reported for optically guided systems.     

前路枢椎椎弓根螺钉的解剖学测量和CT扫描数据的差异性分析

目的探讨经口前路枢椎椎弓根螺钉解剖学与CT测量数据的差异性。方法对60具成年人枢椎标本进行解剖学测量,对20具成年人枢椎标本进行CT钉道扫描,比较解剖学测量和CT扫描两种测量方式其进针点至前正中线的距离、椎弓根的骨性钉道长度、进针的外倾角和下倾角等置钉参数的差异性。结果两种方式在测量椎弓根进钉点至前正中线的距离（左侧、右侧和双侧测量）、骨性钉道长度（左侧和双侧测量）、进钉外倾角（右侧和双侧测量）和下倾角（左侧、右侧和双侧测量）等指标上的差异均有统计学意义（P〈0.05）。结论解剖学测量与CT钉道扫描所获得的螺钉置入数据存在一定的差异性,因此临床工作中应综合考虑两种方法的测量结果,在此基础上确定最佳进钉点和进钉角度。     

计算机辅助下颌骨截骨的三维显微结构模型建立

目的 探索计算机重建下颌骨三维显微结构模型及下颌角截骨手术的三维仿真操作方法 ,以减少手术操作中的组织损伤. 方法 利用螺旋CTA数据重建包含血管神经束的下颌骨三维模型并进行测量分析,使用Freeform雕刻刀及其布尔运算的切割方法 对模型进行保护血管的手术模拟.结果 利用计算机辅助技术可以精确的重建包含下牙槽动脉的下颌骨三维模型:血管从下颌孔进入下颌支.依照下颌支外缘弧度走行,下颌孔距下颌支前缘距离为(19.13±0.66)mm,孔距下颌支后缘距离为(18.96±0.64)mm,下颌角的角度为(109.70±4.67)°,下颌支的安全截骨范围和角度是平行下颌支外缘(12.62±0.28)mm宽、与下颌底成角(22.30±4.67)°;根据模型与数据,Fredorm可以模拟安全的下颌角截骨的手术操作. 结论 下颌骨显微结构的三维模型重建和测量分析技术,是增加手术安全性的一条新途径.     

颈椎椎间孔三维CT测量的实验研究

目的:对颈椎椎间孔三维CT测量的准确性进行评估。方法:成人尸体颈椎标本5个,在椎间孔走向垂直的方向切割椎间孔,范围为C2~C7。观察椎间孔的解剖形态并测量其面积。标本行螺旋CT检查,并将图像传送至三维CT图像处理工作站。在不同阈值下进行三维重建,计算出诸椎间孔面积,并将所得数据与标本同一椎间孔的实体测量结果比较。结果:颈椎椎间孔在300Hu阈值下的测量值与标本测量值之间无显著性差异(P>0.05)。结论:三维CT对椎间孔的形态大小可作出正确的评估。