Comparison between cone-beam and multislice computed tomography for identification of simulated bone lesions

There are many studies that compare the accuracy of multislice (MSCT) and cone beam (CBCT) computed tomography for evaluations in the maxillofacial region. However, further studies comparing both acquisition techniques for the evaluation of simulated mandibular bone lesions are needed. The aim of this study was to compare the accuracy of MSCT and CBCT in the diagnosis of simulated mandibular bone lesions by means of cross sectional images and axial/MPR slices. Lesions with different dimensions, shape and locularity were produced in 15 dry mandibles. The images were obtained following the cross sectional and axial/MPR (Multiplanar Reconstruction) imaging protocols and were interpreted independently. CBCT and MSCT showed similar results in depicting the percentage of cortical bone involvement, with great sensitivity and specificity (p < 0.005). There were no significant intra- or inter-examiner differences between axial/MPR images and cross sectional images with regard to sensitivity and specificity. CBCT showed results similar to those of MSCT for the identification of the number of simulated bone lesions. Cross sectional slices and axial/MPR images presented high accuracy, proving useful for bone lesion diagnosis.     

健康青年人髁突松质骨结构锥形束CT分析

目的探讨锥形束CT测量下颌骨髁突松质骨结构的可行性，了解下颌骨髁突松质骨结构的分布特点。方法用锥形束CT对40名健康青年志愿者（20～32岁）的80侧下颌骨，获取髁突冠状位正中层面图像，用自行设计的图像分析软件对图像进行二值化处理，并分8区对松质骨结构参数进行分析，包括单位体积内的松质骨体积即骨小梁体积分数、测量范围内骨小梁的平均厚度即骨小梁厚度、单位毫米长度内骨小梁数目及骨小梁间的平均空间距离即小梁分离度。结果髁突上区与中、下区的所有松质骨结构参数值均不同，差异有统计学意义（P〈0．05）；髁突上区骨小梁体积分数最高（52．2％），骨小梁数目最多（1．33mm^-1），骨小梁厚度（393．48μm）和骨小梁分离度（361．59μm）最小；两侧髁突松质骨的结构参数值差异无统计学意义（P〉0．05）。结论下颌骨髁突内部的松质骨结构分布不均，但两侧的分布对称；用锥形束CT结合图像分析技术可以实现髁突松质骨结构的体内定量分析。     

下颌骨髁突骨密度的相关性研究

目的利用锥形束CT(cone beam computed tomography,CBCT)测量下颌骨髁突骨密度,研究下颌骨髁突骨密度与性别、年龄、垂直及矢状骨面型的相关性。方法收集700例患者正畸治疗前的CBCT数据,将患者按照性别、年龄、垂直骨面型和矢状骨面型进行分组,测量双侧水平面下颌骨髁突最大径处的髁突骨皮质密度、骨松质密度及总体骨密度,比较各组间测量值。结果女性的骨皮质密度及总体骨密度均值明显高于男性(P<0.05)。与年龄较小组相比,年龄较大组的骨皮质密度及总体骨密度均值明显增高,各年龄组间差异有统计学意义(P<0.05)。垂直骨面型中,低角组的髁突骨皮质密度均值明显大于均角组(P<0.05)。矢状骨面型中,Ⅱ类组的髁突骨松质密度均值明显高于Ⅰ类组,且Ⅱ类组髁突总体骨密度平均值最高,与Ⅰ类组和Ⅲ类组之间存在显著差异(P<0.05)。矢状向Ⅰ类组中,低角组的髁突骨松质密度明显高于均角组及高角组,低角组总体骨密度高于均角组,且差异有统计学意义(P<0.05)。结论性别、年龄、垂直骨面型和矢状骨面型都会对下颌骨髁突骨密度造成影响,因青少年髁突处在生长发育期,正畸医生在治疗时应充分考虑这些因素。     

牙颌面锥形束CT与曲面体层X线检查对颌骨牙骨质瘤样病变诊断价值的比较研究

目的:比较牙颌面专用CBCT与曲面体层对颌骨牙骨质瘤的诊断价值。方法:对3例发生于上下颌骨中的牙骨质瘤患者,分别选用曲面体层和CBCT检查,并将检查结果进行比较分析,判断相互之间的一致性和差异性。结果:3例上下颌骨内牙骨质瘤病变,在曲面体层上均有显示,但CBCT检查可以在矢状位、冠状位和横断面上以多个层面准确地反映病变的位置及骨质破坏的情况。结论:CBCT在对上下颌骨牙骨质瘤的诊断较曲面体层更为有价值。     

Cone beam computed tomography 3D reconstruction of the mandibular condyle

OBJECTIVE: To determine the ideal window level and width needed for cone beam computed three-dimensional (3D) reconstruction of the condyle. MATERIALS AND METHODS: Linear dimensions were measured with a digital caliper to assess the anatomic truth for 50 dry human mandibular condyles. Condyles were scanned with the i-CAT cone beam computed tomography (CBCT) and 3D-models were reconstructed. Three linear three-dimensional measurements were made on each of the 50 condyles at 8 different Hounsfield unit (HU) windows. These measurements were compared with the anatomic truth. Volumetric measurements were also completed on all 50 condyles, at 23 different window levels, to define the volumetric distribution of bone mineral density (BMD) within the condyle. RESULTS: Significant differences were found in two of the three linear measurement groups at and below the recommended viewing window for osseous structures. The most accurate measurements were made within the soft tissue range for HU window levels. Volumetric distribution measurements revealed that the condyles were mostly comprised of low-density bone, and that condyles exhibiting significant changes in linear measurements were shown to have higher percentages of low-density bone than those condyles with little change from the anatomic truth. CONCLUSIONS: CBCT assessment of the mandibular condyle, using the 3D reconstruction, is most accurate when accomplished at density levels below that recommended for osseous examination. However, utilizing lower window levels which extend into the soft tissue range, may compromise one's capacity to view the bony topography.     

54例正常人双侧颞下颌关节CBCT测量值分析

目的：探讨应用CBCT（cone-beamcomputedtomography）对成年人两侧颞下颌关节进行多项指标数据测量分析。方法：在TMJ成像与测量技术的基础上，筛选出正常成人54例，通过严格的TMJ临床检查确定为健康关节，利用Newtom9000CBCT对其ICP位颞下颌关节进行成像后测量分析。结果：在轴位测得髁状突水平角以及单侧髁状突距矢状中线的距离；平行于髁状突长轴的斜位，测髁状突长轴径，垂直角度，沿髁状突长轴顶内外极间任意角间隙宽度；垂直于髁状突长轴的斜位测量关节髁状突前中后任意角间隙宽度，关节凹深度和前斜面角度关节颈厚度；矢状位测关节髁状突前中后任意角间隙宽度，关节凹深度和前斜面角度关节颈厚度。结论：正常成人双侧髁状突位置及关节窝形态性别差异不明显，双髁状突位置及关节窝形态基本对称。     

Comparison of periapical radiography and limited cone-beam computed tomography in mandibular molars for analysis of anatomical landmarks before apical surgery

Introduction

The purpose of the present study was to evaluate the detectability and dimensions of periapical lesions, the relationship of the mandibular canal to the roots of the respective teeth, and the dimension of the buccal bone by using limited cone-beam computed tomography (CBCT) in comparison to conventional periapical (PA) radiographs for evaluation of mandibular molars before apical surgery.

Methods

The study comprised 38 molars with 75 roots. The type of PA lesion as diagnosed on PA radiographs was compared with the type of lesion seen on sagittal and coronal CBCT sections. The distances of the apices of the first mandibular molars and basal border of the PA lesion to the coronal lining of the mandibular canal were assessed with PA radiographs and corresponding sagittal and coronal CBCT images. Furthermore, coronal CBCT images were used to measure the distance from the apices to the buccal bone surface and the corresponding width of the cortical bone plate.

Results

Of 58 detected PA lesions, 15 (25.9%) lesions diagnosed with sagittal CBCT slices were missed with PA radiography. The distance between the apices and the upper border of the mandibular canal was only measurable in 24 of 68 radiographs (35.3%) by using PA images. The cortical bone wall had a mean thickness of 1.7 mm, whereas the total buccal bone wall (cortical and spongious) measured 5.3 mm on average.

Conclusions

The present study highlights the advantages of using limited CBCT for treatment planning in mandibular molars before apical surgery.     

锥形束CT在下颌骨肿瘤和肿瘤样病变检查中的应用

目的:探讨锥形束计算机体层摄影术( CBCT)在下颌骨肿瘤和肿瘤样病变检查中的应用价值。方法:回顾性分析16例经病理证实的下颌骨肿瘤和肿瘤样病变的CBCT资料,包括轴面、冠状面、矢状面、曲面重建图像及VR图像,评价病变的大小、形态、范围、内部结构特征,及其与邻近牙齿、下颌神经管的解剖关系,并与术中所见相比较。结果:13例病变中,牙瘤6例,成釉细胞瘤3例,角化囊性瘤3例,骨化性纤维瘤2例,骨纤维异常增殖症2例,所有病例的形态、范围、内部结构特征,以及与邻近牙齿、下颌神经管的关系显示清楚,与术中所见一致。结论:CBCT扫描能够全面提供下颌骨肿瘤和肿瘤样病变的影像学信息,可作为术前常规检查。     

单侧后牙长期缺失后髁突形态的锥形束CT研究

目的采用锥形束CT（CBCT）研究单侧后牙长期游离缺失对双侧髁突形态的影响。方法收集30例单侧后牙长期游离缺失患者和30例正常对照者的CBCT图像,应用Mimics 15.0软件测量双侧髁突体积、面积、线距及骨密度,对测量结果进行统计学分析。结果缺牙侧的髁突体积、髁顶体积及其骨密度明显小于非缺牙侧（P<0.05）;髁突横截平面的面积及其骨密度大于非缺牙侧（P<0.05）。结论单侧后牙长期游离缺失后,双侧髁突均发生适应性改建,缺牙侧髁突小于非缺牙侧。     

锥形束CT与根尖片对beagle犬显微根尖手术的预后评估

目的:采用根尖片和锥形束CT(cone beam computed tomography, CBCT)对beagle犬实验性根尖周炎显微根尖手术的预后进行评估。方法:将3条beagle犬18颗前磨牙髓腔暴露于口腔环境中8周, 拍摄根尖片及CBCT显示36个牙根均形成实验性根尖周炎。根管治疗后行显微根尖外科手术,术后即刻、6月分别拍摄根尖片和CBCT,根据根尖片和CBCT的根尖透射影像面积,比较二者在识别根尖骨质缺损的差别。结果:显微根尖手术后即刻CBCT矢状面、冠状面根尖透射影像面积均大于根尖片,差别具有统计学意义(P=0.000,P=0.026);CBCT矢状面、冠状面比较两组间差别无统计学意义(P=0.070)。显微根尖手术后6月复查CBCT矢状面、冠状面根尖透射影像面积均大于根尖片,差别具有统计学意义(P=0.000,P=0.012);CBCT矢状面根尖透射影像面积大于冠状面,两组间差别有统计学意义(P=0.001)。结论:CBCT在根尖周骨质缺损的识别优于根尖片,CBCT在根尖手术骨缺损预后评估中是一项有效的评价手段。     

Associations between the articular eminence inclination and condylar bone changes, condylar movements, and condyle and fossa shapes

Objectives

The purpose of the present study was to determine the inclination and height of the articular eminence with respect to the condylar bone changes, condyle shape, fossa shape and condylar movements in patients with and without temporomandibular joint (TMJ) dysfunction using cone-beam computed tomography (CBCT).

Methods

The associations between the eminence inclination and the condylar bone changes, condylar movements, condylar shape and fossa shape were evaluated in patients with TMJ disorders and control patients without TMJ disorders. The measurements of the articular eminence inclination were established on central sagittal slices of the TMJ. The central coronal slices were used to determine the condyle and fossa shapes. The types of movements of the condyles were determined on open-mouth images, and mandibular hypermobility or hypomobility was noted for each joint.

Results

There were no significant differences in the eminence inclination and height with respect to the condylar bone changes and condylar movements in the TMJ disorder group. However, there was a significant association between the eminence inclination and the fossa shape in the TMJ disorder group and significant associations between the eminence inclination and both the condyle and fossa shapes in the control group. The articular eminence inclination was steeper in the control group than in the TMJ disorder group.

Conclusions

The eminence inclination was steeper in the control patients than in the patients with TMJ disorders, and was not correlated with the condylar bone changes or condylar movements.     

EVALUATION OF SIMULATED BONE LESION IN THE HEAD OF THE MANDIBLE BY USING MULTISLICE COMPUTED TOMOGRAPHY

Conventional radiography has shown limitation in acquiring image of the ATM region, thus, computed tomography (CT) scanning has been the best option to the present date for diagnosis, surgical planning and treatment of bone lesions, owing to its specific properties. Objective: The aim of the study was to evaluate images of simulated bone lesions at the head of the mandible by multislice CT. Material and methods: Spherical lesions were made with dental spherical drills (sizes 1, 3, and 6) and were evaluated by using multislice CT (64 rows), by two observers in two different occasions, deploying two protocols: axial, coronal, and sagittal images, and parasagittal images for pole visualization (anterior, lateral, posterior, medial and superior). Acquired images were then compared with those lesions in the dry mandible (gold standard) to evaluate the specificity and sensibility of both protocols. Statistical methods included: Kappa statistics, validity test and chi-square test. Results demonstrated the advantage of associating axial, coronal, and sagittal slices with parasagittal slices for lesion detection at the head of the mandible. Results: There was no statistically significant difference between the types of protocols regarding a particular localization of lesions at the poles. Conclusions: Protocols for the assessment of the head of the mandible were established to improve the visualization of alterations of each of the poles of the mandible''s head. The anterior and posterior poles were better visualized in lateral-medial planes while lateral, medial and superior poles were better visualized in the anterior-posterior plane.     

The potential of hybrid SPECT/CT fusion imaging to improve diagnostic accuracy in the scintigraphic quantitative functional assessment of suspected unilateral mandibular hyperactivity

Background

Mandibular asymmetry is commonly caused by disproportionate mandibular growth due to unilateral condylar hyperactivity. The current standard for mandibular condyle bone scintigraphy uses single photon emission computed tomography (SPECT) imaging after intravenous administration of technetium-99m-labeled diphosphates. To our knowledge, the use of hybrid SPECT integrated with multidetector computed tomography (SPECT/CT) imaging in the scintigraphic quantitative functional assessment of mandibular condyle growth has not yet been described.

Case report

A 22-year-old male with mandibular asymmetry due to suspected unilateral condylar hyperactivity underwent SPECT/CT imaging of the skull and facial bones after intravenous administration of technetium-99m methylene diphosphonate. Using CT to guide anatomical contouring, precise regions of interest were drawn over the mandibular condyles and clivus in adjacent SPECT/CT transaxial slices to calculate the mean radiotracer count ratios. For comparison of quantitative results, conventional SPECT images were obtained from the SPECT/CT data and processed according to conventional methods. Planar images were also obtained for visual assessment of mandibular condyle activity. All three methods, SPECT/CT, conventional SPECT, and planar imaging, found unilateral condylar hyperactivity of the left mandibular condyle. The condyles and clivus were easily and confidently identified on SPECT/CT images.

Discussion

We speculate that SPECT/CT imaging will improve the diagnostic accuracy of unilateral condylar hyperactivity. More studies are necessary to further define its role, obtain baseline reference values, and establish analysis protocols.     

颞下颌关节髁突囊样变的锥形束CT影像特点

目的 利用口腔颌面锥形束CT观察髁突囊样变的影像学表现,探讨囊样变的影像特点并加以分类。方法 收集颞下颌关节锥形束CT影像学表现有囊样变的194例患者,观察并记录囊样变的部位、大小、数量、边缘骨白线、周围骨小梁结构、髁突整体骨质情况。根据髁突整体骨质情况,将髁突囊样变分为Ⅰ型和Ⅱ型,比较其发生的部位、数量、边缘骨白线以及周围骨小梁结构情况。结果 194例患者的198侧关节发现囊样变表现,94例位于左侧关节,96例位于右侧关节,4例位于双侧关节。50.0%（99侧）的囊样变位于髁突前外侧皮质骨下方;囊样变直径最小1.2 mm,最大13.5 mm,平均（3.4±1.5）mm;75.3%（149侧）为单发囊样变;62.6%（124侧）存在完整的骨白线包绕;80.8%（160侧）周围骨小梁结构有骨质硬化。66.7%（132侧）囊样变髁突表现有晚期骨关节病征象,5.1%（10侧）囊样变髁突表现有早期骨关节病征象,28.3%（56侧）髁突除囊样变外无其他明显骨质改变。Ⅰ型和Ⅱ型髁突囊样变在发生部位、数量和周围骨小梁结构方面存在差异,Ⅰ型髁突囊样变较多发和骨质硬化,Ⅱ型髁突囊样变发生于髁突内部或髁突颈部较多。结论 Ⅰ型和Ⅱ型髁突囊样变在发生部位、数量和周围骨小梁结构存在不同,这可能与其病因及形成机制不同有关。     

根尖周病中锥形束CT与根尖片识别病损差异的研究进展

随着影像学技术的进步,锥形束CT（CBCT）作为口腔临床检查的一种辅助手段,已经广泛应用于口腔医学的各个领域。它具有分辨率高、辐射量低、成像迅速、三维重建、失真小、对硬组织成像好等诸多优点。传统的根尖片是以二维图像的形式显示三维物体及其周围结构,仅显示重叠的近远中向骨质破坏,不能显示颊舌向骨质破坏。CBCT作为一种三维成像技术,可以从矢状位、冠状位和轴位显示组织的三维结构,克服了根尖片二维图像重叠、变形等缺陷。CBCT的三维成像技术较传统根尖片具有独特优势,与根尖片相比,CBCT在观察骨质结构和根尖骨质破坏方面具有更高的灵敏度。本文就CBCT与根尖片在根尖病损识别中的差异研究进展作一综述。     

A CBCT study on positional change in mandibular condyle according to metallic anchorage methods in skeletal class III patients after orthognatic surgery

PurposeThis study was to evaluate the postoperative stability of the mandibular condyle according to the number of screws in the proximal segment using cone beam computed tomography (CBCT).Patients and methodsThirty patients diagnosed with skeletal class III malocclusion and underwent sagittal split ramus osteotomy (SSRO) were enrolled in this study. In Group A, 4 screws and a 4-hole miniplate were used for the internal fixation of an osteotomy and 3 screws, only 1 screw in the proximal segment, and a 4-hole miniplate were used in Group B. We digitally measured anteroposterior, supero-inferior, and mediolateral positions and angles of the long axis of the mediolateral poles in CBCT scans pre-operatively, within 1 week postoperatively and 3, 6 months after surgery.ResultsThe condylar head angle in the axial plane showed consistent and significant changes. The condylar head angle in the coronal plane decreased in both groups, which shows that condylar heads bent inward. In the axial plane, Group A showed statistically significant differences while Group B did not in early stage (T0–T1–T2). The change in distance between condylar heads shows that these have moved outward in both groups.ConclusionThe results show that a fixation method using 3 screws with a 4-hole miniplate did seemed preferable and may give some flexibility for condylar heads to be positioned in physiologic position during postoperative phase.     

克氏针治疗下颌骨髁突矢状骨折13例回顾性分析

目的探讨克氏针内固定方式在下颌髁突矢状骨折治疗中的应用价值。方法回顾分析2019年1月至2020年1月在广州中医药大学附属佛山市中医院口腔医疗中心就诊的下颌骨髁突矢状骨折复位后采用克氏针内固定治疗的患者,共13例19侧。治疗过程包括常规手术切开、暴露并复位游离的下颌骨髁突后,根据下颌骨髁突骨质断端情况利用2~4根克氏针固定,伴发其他部位骨折时同期手术治疗。术后1周通过CBCT评估游离的下颌骨髁突复位精准度及稳固性,通过临床检查评价咬合关系、开口度、开口型。结果所有患者骨折断端对位良好,克氏针无扭曲、折断和松脱;术后咬合关系、开口度、开口型恢复良好。结论克氏针治疗下颌骨髁突矢状骨折效果确切,有临床应用价值。     

单侧有一种症状的TMD患者双侧关节CBCT对比研究

目的：探讨单侧有一种症状的颞下颌关节紊乱病（ TMD）患者双侧颞下颌关节（ TMJ）在CBCT成像上可能存在差异的参考层面。方法：选取仅单侧有症状的TMD患者29例,通过CBCT三维成像和重建,观察两侧TMJ重建后横断面的水平角;平行于髁突长轴的斜位关节间隙、髁突长轴径值、髁突垂直角;垂直于髁突长轴的斜位与矢状位的关节结节斜度、关节窝深度和关节间隙,采用SPSS13．0软件对各测量指标做两样本配对t检验。结果：两侧TMJ在垂直位60°关节间隙时的测量值差异有统计学意义（P＜0．05）,其余测量值均无统计学意义（P＞0．05）。结论：对于单侧有一种症状的TMD患者,接近矢状位是较易观察到左右两侧有差异的位置,并可观察到患侧前间隙增大,在此层面重建对诊断和对比研究更有参考价值。     

Condylar subchondral formation of cortical bone in adolescents and young adults

We investigated subchondral formation of cortical bone in the condyles of adolescents and young adults, and looked for age-related and sex-related differences in bony formation with the aid of cone-beam computed tomography data in 1438 subjects aged between 10 and 30 years. The scans were part of the hospital's clinical protocol for patients seeking orthodontic or orthognathic treatment. No patient had signs or symptoms of temporomandibular disorders. Central images of the coronal and sagittal planes of the condyle were acquired and scored. Subchondral formation of cortical bone was seen as a high-density compact linear image, and subjects were classified into complete, partial, and no formation. Subchondral formation of cortical bone was first seen at the ages of 13–14 in boys and 12–13 in girls. Complete cortical bony formation was seen after the age of 22 years for men and 21 for women. We conclude that cortical bone begins to form around the periphery of the condyles during adolescence (12–14 years). A continuous, homogeneous, and compact cortical bony layer is established in young adults by the age of 21–22, indicating full development of the mandibular condyle. The condylar bone developed gradually and was generally fully developed a year earlier in women than men.     

Quantitative bone SPECT analysis of mandibular condyles in an asymptomatic population: an approach to normal reference values

Bone scintigraphy is an extremely valuable technique in diagnosis and treatment planning for patients with condylar hyperplasia (CH). The main objective of this study was to develop an approach to determine normal activity values in the mandibular condyles, adjusted to age and sex, through quantitative analysis of bone single-photon emission computed tomography (SPECT) on a condyle-by-condyle basis and to compare these values with those of a control group comprising patients with confirmed CH. Technetium 99 m-methylene diphosphonate (^99mTc-MDP) SPECT studies of the mandibular condyles were performed in patients with no mandibular pathology for quantitative analysis. Regions of interest were drawn on slices representing the upper, middle, and inferior thirds of each condyle and on the summation of transaxial slices representing the whole condyle (three-dimensional approach). The clivus was used for internal validation and the condyle to clivus ratios were calculated. These ratios were compared between ‘normal’ and ‘diseased’ condyles. A total 144 condyles in normal patients and 25 in confirmed CH patients were analysed. Differences between the ratios were evaluated through the coefficient of variation. In normal patients, the ratios to the clivus on the summed condyle image showed the lowest variability: range 0.3–1.28 (median 0.74). The quantile regression model showed significant differences with respect to sex, but not to age. The Mann–Whitney test showed significant differences in the ratios to clivus between normal and diseased condyles (P < 0.0001).