多发性对称性脂肪增生病的CT和MRI表现

目的总结多发性对称性脂肪增生病的影像学表现。方法回顾分析12例多发性对称性脂肪增生病的CT和MRI表现。结果异常增多的脂肪组织主要沉积于颈前和项部皮下组织、胸锁乳突肌和斜方肌深面、颈后三角、颌下腺和腮腺周围，也见于锁骨上窝、围绕脊柱旁肌肉、咽后间隙、喉等部位，导致颈部诸结构受压。病变脂肪组织的密度和信号与正常脂肪组织的密度和信号相同。结论CT和MRI能准确反映增厚脂肪的分布范围及其对周围器官组织的压迫情况，并能排除软组织肿瘤。     

Personal computer equipment for dental digital subtraction radiography vs. industrial computer equipment and conventional radiography

A "low-cost" personal computer (PC) system used to digitize dental radiographs was tested by assessing the accuracy of its subtraction images versus those of "high-cost" industrial equipment and conventional radiography. Subtraction images were made of artificial lesions in human femur bone and subsequently evaluated by students and teachers. The observations were analyzed in terms of true positive and false positive reports. "Low-cost" and "high-cost" subtraction images revealed only small differences in diagnostic accuracy. Compared to conventional radiography, the diagnostic accuracy of the subtraction images with the "low-cost" PC system was significantly higher for all observers. The interexaminer variance was similar for the subtraction and the conventional images for both students and teachers, except for a significantly reduced interexaminer variance for the teachers concerning the true positive reports with the "low-cost" PC subtraction technique.     

数字口内X线片和口腔颌面锥形束CT对邻面龋诊断准确性的研究

目的 比较锥形束CT( cone beam computed tomography,CBCT)与数字口内X线片对邻面龋诊断的准确性,为临床提供适宜的检查手段.方法 5名观察者对45颗离体牙CBCT图像和数字口内片影像进行评估后得出受试者工作特征(receiver operating characteristic,ROC)曲线.结果 邻面龋(牙釉质+牙本质)诊断中CBCT与数字口内片比较,差异无统计学意义(P =0.186)；单纯分析牙本质龋:CBCT与数字口内片比较差异有统计学意义(P =0.004)；单纯分析牙釉质龋:CBCT与数字口内片比较差异无统计学意义(P =0.885).结论 虽然诊断邻面牙本质龋时CBCT优于数字口内片,但因其辐射剂量因素,故不推荐使用CBCT诊断邻面龋.     

Image contrast range for detection of enamel defects using a digital dental imaging system

The purpose of this study was to quantitatively assess the acceptable range of image contrast for the detection of enamel defects by adjusting the contrast and brightness of a digital dental imaging system. Extracted human premolars and molars with enamel defects on the proximal surfaces were mounted in maxillary and mandibular sets on phantoms. The phantoms were individually exposed and processed with a digital dental imaging system from Computed Dental Radiography (CDR, Schick Technologies, Inc., NY, USA). The images were transferred to a personal computer, and the contrast and brightness were determined in the range of ±100 digital digit numbers (DDN) using Adobe Photoshop 4.0.1 J (Adobe Systems Inc., Tokyo, Japan). The 8-bit CRT display used was set at maximum inherent brightness. The relationship between the pixel value and the DDN in contrast at both the enamel and the background on the monitor was used to measure the acceptable image contrast by manipulating contrast and brightness. Six dental radiologists were asked to determine the presence or absence of enamel defects. The detectability was statistically analyzed using Fisher's protected limited standard deviation (PLSD) non-parametric test. When the inherent brightness on an 8-bit CRT display was adjusted to the maximum, there was an acceptable range of image contrast and brightness for the detection of enamel defects with this digital dental imaging system.     

成人正畸治疗与颞下颌关节紊乱病的MRI研究

目的 探讨成人正畸治疗与颞下颌关节紊乱病(temporomandibular disorder TMD)的关系,为预防和治疗TMD提供参考.方法 选择60例20 ～ 29岁成年正畸患者,用Helkimo指数将患者分为TMJ无症状组(44例)、TMJ有症状组(16例),分别于治疗前(t1)、治疗中(t2)、治疗后(t3),用MRI检查TMJ关节盘的位置,并用电子测量尺测量TMJ前、后间隙,观察颞下颌关节在治疗前后的变化情况与TMD间的关系.结果 治疗中TMJ无症状组、TMJ有症状组分别有8、9例患者发生TMD,两组TMD发生比例差异有统计学意义(P＜0.05);治疗前后两组均发现关节盘移位;两组治疗前后TMJ各间隙线距发生改变,但两组差异无统计学意义(P＞0.05).结论 成人正畸治疗不会导致TMD,但治疗过程中可诱发TMD症状,并有出现TMD重度症状的风险.在成人正畸治疗前对TMJ进行评估有重要意义.     

阻塞性睡眠呼吸暂停低通气综合征患者上气道阻塞的动态MRI分析

目的研究阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者清醒和睡眠时上气道阻塞的情况及其变化。方法21例OSAHS患者经20h无睡眠后,分别在清醒与睡眠状态下,获得上气道正中矢状面的动态MRI影像。配对t检验比较清醒和睡眠时上气道阻塞区长度的差异。结果12例OSAHS患者清醒时有腭咽区阻塞,21例患者睡眠时均有腭咽区阻塞,清醒时和睡眠时腭咽区阻塞的符合百分比为57·14%。12例患者清醒时上气道阻塞区长度的最大值(2·99±0·51)cm、最小值(0·72±0·23)cm,两者差值(2·27±0·67)cm,分别比睡眠时的最大值(6·61±1·23)cm、最小值(0·95±0·22)cm、两者差值(5·66±1·27)cm小,差异均有统计学意义(P<0·01)。结论OSAHS患者睡眠时上气道的阻塞是变化的、多区域的。OSAHS患者清醒时上气道的阻塞仅在一定程度上提示睡眠时的阻塞情况。     

Subjective image quality assessment of cross sectional imaging methods for the symphyseal region of the mandible prior to dental implant placement

Objectives

A three dimensional appreciation of the form of the anterior mandible is required to place dental implants safely in the region. This study compared the subjective image quality of four available methods of cross sectional imaging of the symphyseal region, the lateral cephalometric view, cone beam computed tomography (CBCT), spiral tomography and the transymphyseal X-ray view.

Methods

An experimental water phantom was developed to reproduce human soft tissue around the mandible. Images were taken of four mandibles by the four X-ray techniques. Three different CBCT machines were included.The source of each image was disguised by displaying all images in the same format on the same computer screen. A protocol was developed to process the images for viewing whilst preserving their image quality.A panel of observers of ten dentists viewed the images and rated their image quality by recording their agreement with six statements on a five point Likert scale.

Results

The results showed a statistically significant difference in image quality between imaging methods. There were clear differences in the ratings between the three cone beam computed tomography machines. Small volume, high resolution CBCT provided images with the highest scores for subjective image quality.

Conclusions

Within the limitations of this study, significant differences in subjective image quality were found between imaging systems used for cross sectional imaging for the symphyseal region of the mandible prior to dental implant placement.     

Accuracy of oral mucosal thickness measurements using spiral computed tomography

Background: Assessment of oral mucosal thickness is important in implant surgery; however, examining the soft tissue three dimensionally is difficult. A reamer method is invasive, and a non‐invasive ultrasonic method produces only low‐resolution images depending on anatomic variations. The emerging technology of spiral computed tomography (CT) is an alternative to the conventional methods. Spiral CT has been a useful diagnostic tool in implant surgery. Although it delivers high radiation doses, spiral CT provides three‐dimensional imaging of low‐contrast structures. The purpose of the present study is to assess the accuracy of oral mucosal measurements using spiral CT. Methods: Thickness of maxillary oral mucosa was measured in five cadavers. The measurement sites were set up in buccal, palatal, and middle of the crest in the missing tooth area in the incisor, canine, premolar, and molar regions. Each cadaver was exposed to spiral CT after installing the measurement guide. After that, each site was physically measured by reamer. Linear regression and correlation analysis were performed to describe the association between radiographic and physical measurements. Results: A total of 114 measurements were performed with statistical analyses. Mean values and standard deviations of physical and radiographic measurements were 3.12 ± 1.43 and 2.83 ± 1.70 mm, respectively. The radiographic and physical measurements demonstrate strong correlation (r = 0.90; P <0.01). Measurement error was 0.52 ± 0.36 mm. According to the regions, the measurements in buccal, palatal, and missing tooth region depicted a significant correlation (r = 0.92, r = 0.85, and r = 0.91, respectively). The boundary of the bone and mucosa was indistinguishable at 23 buccal sites. Twenty‐three measurements that could not be distinguished with CT had a mean of 0.69 and standard deviation ± 0.13 mm. Conclusions: The correlation between spiral CT and physical measurement was high except in sites of very thin mucosa. Spiral CT can be considered an alternative method for the measurement of oral mucosal thickness. Because of the higher radiation exposure, caution should be exercised and radiation dosage versus clinical benefit assessment is required.     

安氏Ⅲ类错(牙合)畸形患者翼外肌MRI研究

目的 通过MRI观察安氏Ⅲ类错(牙合)畸形患者翼外肌结构,探讨Ⅲ类错(牙合)畸形导致颞下颌关节紊乱病的潜在危险性.方法利用MRI对24例安氏Ⅲ类错(牙合)畸形患者(Ⅲ类错(牙合)组)和10名健康对照者(健康对照组)进行翼外肌成像研究.观察两组翼外肌病理结构及Ⅲ类错(牙合)组病理结构与颞下颌关节紊乱病体征的关系.结果Ⅲ类错(牙合)组翼外肌存在肌肉肥大、挛缩和萎缩等病理改变(36侧),并与健康对照组翼外肌病理改变(2侧)的差异有统计学意义(P＜0.01).安氏Ⅲ类错(牙合)畸形患者有翼外肌的病理改变,但多不伴颞下颌关节紊乱病的临床症状.结论安氏Ⅲ类错(牙合)畸形比正常(牙合)可更多地引起翼外肌的病理改变,有发生颞下颌关节紊乱病的潜在危险.     

口腔鳞状细胞癌淋巴结转移全身MRI弥散加权成像表现

目的 探讨口腔鳞状细胞癌患者淋巴结转移在全身MRI弥散加权成像中表现及临床意义.方法 对21例口腔鳞状细胞癌伴淋巴结转移的患者行全身MRI弥散加权成像(whole-body diffusion weighted imaging,WB-DWI)检查,处理生成的全身表观弥散系数图.其中19例行常规MRI增强扫描,9例用正电子发射体层摄影术(positron-emission tomography,PET)检查.全部病例淋巴结均经病理证实.结果 21例患者WB-DWI发现异常淋巴结139个,正常淋巴结11个,炎性淋巴结21个.转移淋巴结呈高信号,表观弥散系数(apparent diffusion coefficient,ADC)值(0.78±0.07)下降,与正常(1.78±0.16)或炎性淋巴结(1.18±0.15)ADC值比较,差异有统计学意义(P<0.05).结论 全身MRI弥散加权技术在鉴别正常淋巴结、炎性淋巴结与肿瘤转移性淋巴结方面能够提供准确的信息,是肿瘤患者全身检查的重要方法.     

Neuromuscular objectives of the human masticatory apparatus during static biting

OBJECTIVE: The central nervous system controls the muscles of mastication and may dictate muscle outputs according to a biologically important objective. This study tested the hypotheses that (a) the effective sagittal TMJ eminence morphology, and (b) the outputs of the masticatory muscles during static biting, are consistent with minimisation of joint loads or minimisation of muscle effort. DESIGN: Numerical modelling predicted effective eminence morphology (from sagittal plane directions of TMJ force for centred loading over a range from molar to incisor biting) and TMJ and muscle forces during static unilateral biting in seven subjects. In vivo effective eminence morphology was measured from jaw tracking recorded from each subject. Muscle activities during biting tasks on first molar and incisor teeth were measured by electromyography using surface or indwelling electrodes. RESULTS: Subject-specific predicted effective eminence morphology correlated with in vivo data (0.85< or =R2< or =0.99). Mixed and random coefficient analysis of covariance indicated good agreement between predicted and measured muscle outputs for all muscles of mastication investigated. Individual linear regression analysis showed that modelled muscle outputs accurately predicted EMG data, with average errors of 8% for molar and 15% for incisor biting. CONCLUSIONS: Effective sagittal eminence morphology was consistent with minimisation of joint loads for all subjects. Masticatory muscle outputs during unilateral biting were consistent with minimisation of joint loads or minimisation of muscle effort, or both, depending on the subject. These results are believed to be the first to test model predictions of muscle output during biting for all muscles of mastication.     

种植体支持义齿患者骨感知的大脑皮层适应性初步研究

目的 采用功能性核磁共振成像(functional MRI,fMBl)对"骨感知"的中枢神经基础进行初步探讨.方法 研究对象为北京大学口腔医学院·口腔医院种植中心2005-2007年无牙颌种植修复复查患者和无牙颌初诊患者20例,共分为3组进行紧咬状态的fMRI扫描,SPM 99软件包统计分析及结果判定.结果 常规全口义齿修复(A组=8例)患者在前额叶皮层激活显著,而与咀嚼运动相关的初级感觉运动皮层激活人数较少;种植体支持固定义齿(B组=3例)患者在紧咬时皮层激活与天然牙列者更为接近,在Broca'S区、初级感觉运动皮层、前运动皮层、岛叶、颞上回、丘脑、基底神经节、海马等激活较显著;种植体支持覆盖义齿(C组=9例)患者前额叶皮层、前运动皮层、顶上回、基底神经节、丘脑等激活较多见.结论 种植体支持固定义齿患者的中枢神经系统对种植体的感觉及运动反馈更加接近于天然牙列,提示种植体支持固定义齿的修复方式能够以更自然的方式恢复患者的咀嚼功能;而常规全口义齿修复患者在咀嚼功能的恢复方面与个体运用义齿的学习、记忆及适应性有更显著的关系,有更强的个体差异性.     

38例切牙管囊肿的X线三维影像学分析

目的利用螺旋CT和锥形束CT分析上颌切牙管囊肿的三维影像学特点。方法收集2012年12月至2018年1月于我院就诊的有完整临床资料、病理诊断及螺旋CT或锥形束CT影像的上颌切牙管囊肿患者38例,分析其影像学特点。结果 38例中男性28例,女性10例,年龄13~77岁。26例(68.4%)囊肿位置居中,12例偏左或偏右。囊肿矢状面形态包括轻度扩张型(8例)、全程膨隆型(17例)、区段膨隆型(12例)和移位扩张型(1例)。30例(78.9%)腭侧骨板膨隆,27例(71.1%)累及牙根周围骨质,11例(28.9%)存在根吸收。结论切牙管囊肿以位于切牙管走形范围内的典型低密度形态常见,少数可偏侧发展,甚至主体偏离切牙管。多数病变腭侧骨板膨隆,累及邻牙根周。     

安氏Ⅱ类1分类错殆患者翼外肌MRI表现与关节盘位置和髁突运动度关系的初探

目的 分析安氏Ⅱ类1分类错<牙合>患者翼外肌MRI异常与关节盘位置、髁突运动度的关系. 方法 选择20例安氏Ⅱ类1分类错<牙合>患者(10～12岁),MRI检查双侧翼外肌,卡方检验分析其与关节盘位置、髁突运动度的关系. 结果 40侧关节中18侧(45%)翼外肌异常,与关节盘位置、髁突运动度无明显相关关系. 结论 本组安氏Ⅱ类1分类错胎患者无症状翼外肌异常的比率较高,但不能确定其与关节盘位置、髁突运动度相关.     

Assessing the optimal imaging modality in the diagnosis of jaw osteomyelitis. A meta-analysis

Osteomyelitis is an inflammatory infectious disease that affects bone and bone marrow. Histopathology remains the gold standard method for diagnosis, but imaging modalities also play an important role. We systematically reviewed five articles with comparative studies on plain films, computed tomography (CT) scan, magnetic resonance imaging (MRI), cone beam computed tomography (CBCT), positron emission tomography (PET), single photon-emission computed tomography (SPECT), scintigraphy, and SPECT/CT. Scintigraphy and SPECT/CT has the highest sensitivity of 100%. PET is only to be used in cases of follow up. Orthopantomography (OPG) is the most common initial diagnostic tool despite its low sensitivity. CT provides the necessary specificity needed for radionuclide imaging, which has the highest negative predictive value of 100% and a positive predictive value >95%. SPECT/CT with 100% sensitivity and 85% specificity can be considered as the imaging modality of choice for initial diagnosis and follow up.     

Comparison between the use of magnetic resonance imaging and conebeam computed tomography for mandibular nerve identification

Objective: Conebeam computed tomography (CBCT) and magnetic resonance imaging (MRI) have been used to identify the mandibular nerve but a comparison of the reliabilities of the two imaging modalities has not been performed. It was hypothesized that the reliabilities were not different between the two. Materials and methods: Twelve dental postgraduates in five disciplines were recruited to assess two sets of reformatted oblique images (CBCT and MRI) of 11 patients who were scanned before wisdom teeth extraction. The variance of the identified locations of mandibular nerve, the mental foramen and the mandibular foramen between two sets of images of each patient was compared. Each set of images was rated by assessors to reveal the satisfaction in determining the structures. Results: It was found that by using MRI images, significantly lesser variances and significantly higher satisfactory scores were given by the assessors than by using CBCT images in the identification of the structures. Conclusions: We concluded that MRI is a promising imaging modality that can be used to identify the mandibular nerve when it cannot be found in CBCT images. To cite this article:
Chau A, Comparison between the use of MRI and CBCT for mandibular nerve identification.
Clin. Oral Impl. Res. 23 , 2012; 253–256.
doi: 10.1111/j.1600‐0501.2011.02188.x     

Correlation between temporomandibular joint temporal component pneumatization and morphology: analysis by cone beam computed tomography

The aim of this study was to evaluate whether a correlation exists between temporal bone pneumatization and the morphology of the articular eminence and glenoid fossa. A sample of 100 cone beam computed tomography scans was used, for a total of 200 temporomandibular joints (TMJ). Paracoronal and parasagittal images of the TMJ were evaluated by two examiners. For all TMJ, pneumatization was classified in the mid-lateral direction using a score of 0 or 1, and in the anteroposterior direction using a score ranging from 0 to 3. The inclination and height of the articular eminence and the thickness of the roof of the glenoid fossa were obtained. Pneumatization was found in the mid-lateral direction in 83.5% of the cases and in the anteroposterior direction in 88%. The age of the patient and side did not influence the prevalence or degree of pneumatization (P = 0.051–0.953), but female patients showed more pneumatization in the mid-lateral direction than male patients (P = 0.014). The presence of pneumatization did not affect articular eminence and mandibular fossa morphology. It is concluded that the presence and extent of pneumatization of the TMJ temporal component does not affect its morphology. However, professionals should be aware of the high prevalence of pneumatization and take this into account when performing TMJ assessment.