计算机断层显像技术在动物实验研究中的应用

核医学已发展成为现代技术的一项重要内容,它在动物实验中的应用得以支持。单光子发射型计算机断层显像仪(SPECT)在动物实验方面能提供定量精确的显像技术。本文目的在于对医学领域中包括肿瘤、心血管疾病、脑和神经功能、急性肾衰竭、类风湿关节炎及肝和脾功能等的SPECT显像效果进行概述。     

19例黄色瘤影像分析

通过对１９例黄色瘤影像分析,认为其基本表现为颅骨多发性破坏和肺部网粟粒状浸润,５岁以上儿童有颅骨广泛破坏应首先考虑本病,并应常规摄胸片检查。分析认为,Ｘ线平片检查是认一病的主要手段,ＣＴ和ＭＲＩ可作为必要补充,ＭＲＩ对显示垂体腺的细胞微病变具有重要意义。     

腺性膀胱炎24例的影像学诊断

目的　探讨腺性膀胱炎的影像诊断要点。方法　对 2 4例经膀胱镜及病理确诊为腺性膀胱炎的患者临床表现、膀胱镜超声波、CT及静脉尿路造影 (IVU )检查资料进行回顾性分析。结果　临床表现为血尿 11例 ,尿路刺激症 9例 ,排尿困难 8例 ,肾功能减退 2例。膀胱镜检查 2 2例 ,表现为菜花样改变 11例 ,水肿与滤泡样改变8例 ,粘膜粗糙 3例。18例行 B超检查 ,12例诊断为膀胱占位。行 IVU检查 15例 ,其中 10例诊断为膀胱占位 ,并经CT证实。 2 4例中并发膀胱癌 2例 ;1例多次复发。结论　腺性膀胱炎易与膀胱癌混淆 ,病理检查是确诊的依据 ,CT及 IVU检查能发现病变。CT检查时发现膀胱占位合并膀胱壁较广泛增厚而无壁外侵犯时 ,应高度怀疑本病     

Diagnosis of pulmonary embolism: Ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.     

Simulation of dental collisions and occlusal dynamics in the virtual environment

Semi‐adjustable articulators have often been used to simulate occlusal dynamics, but advances in intra‐oral scanning and computer software now enable dynamics to be modelled mathematically. Computer simulation of occlusal dynamics requires accurate virtual casts, records to register them and methods to handle mesh collisions during movement. Here, physical casts in a semi‐adjustable articulator were scanned with a conventional clinical intra‐oral scanner. A coordinate measuring machine was used to index their positions in intercuspation, protrusion, right and left laterotrusion, and to model features of the articulator. Penetrations between the indexed meshes were identified and resolved using restitution forces, and the final registrations were verified by distance measurements between dental landmarks at multiple sites. These sites were confirmed as closely approximating via measure‐ments made from homologous transilluminated vinylpolysiloxane interocclusal impressions in the mounted casts. Movements between the indexed positions were simulated with two models in a custom biomechanical software platform. In model DENTAL, 6 degree‐of‐freedom movements were made to minimise deviation from a straight line path and also shaped by dynamic mesh collisions detected and resolved mathematically. In model ARTIC, the paths were further constrained by surfaces matching the control settings of the articulator. Despite these differences, the lower mid‐incisor point paths were very similar in both models. The study suggests that mathematical simulation utilising interocclusal ‘bite’ registrations can closely replicate the primary movements of casts mounted in a semi‐adjustable articulator. Additional indexing positions and appropriate software could, in some situations, replace the need for mechanical semi‐adjustable articulation and/or its virtual representation.     

Full arch precision of six intraoral scanners in vitro

PurposeIntraoral scanners may offer an alternative to traditional impressions. That intraoral scanners produce precise scans is essential. Popular methods used to evaluate precision tend to rely on mean distance deviation between repeated scans. Mean value measurements may underestimate errors resulting in misleading conclusions and clinical decisions. This study investigated the precision of six intraoral scanners using the traditional method of measuring mean error, and a proposed method considering only the most extreme and clinically relevant aspects of a scan.MethodsAn edentulous model was scanned five times using six intraoral scanners. The repeated scans were aligned, uniformly trimmed and mean surface deviation measured across all 20 scan combinations within each scanner group. All scan combinations were then measured by arranging scan vertices from greatest to smallest unsigned distance from its compared scan and measuring the median value within the 1% of most greatly deviating points. Traditional mean deviation results and upper-bound deviations were compared.ResultsThe upper-bound deviation within a scan reported errors up to two times greater than those found when measuring global mean distances. Results revealed clinically relevant errors of more than 0.3 mm in scans produced by the Planmeca and Dentalwings scanners, findings not seen when measuring mean distance error of the complete scan.ConclusionsUpper-bound deviation of a cropped scan may provide a clinically useful metric for scanner precision. The Aadva, 3Shape, CEREC and TDS produced scans potentially appropriate for clinical use while Planmeca and Dentalwings produced deviations greater than 0.3 mm when measuring the upper-bound deviation.     

Measurement of three-dimensional perioral soft tissue changes in dentoalveolar protrusion patients after orthodontic treatment using a structured light scanner

Objective:To evaluate the three-dimensional (3D) perioral soft tissue changes after orthodontic treatment in patients with dentoalveolar protrusion using structured light–based scanners.Materials and Methods:Forty-four Korean adults (19 men and 25 women, 21.4 ± 3.4 years) with dentoalveolar protrusion treated by extraction of all four first premolars and then en masse retraction with maximum anchorage were evaluated. Lateral cephalograms and 3D facial scans were obtained before treatment (T1) and immediately after debonding (T2). Superimposition was performed, and 27 perioral landmarks were identified. The 3D changes in the landmarks and ratio of movement of the soft tissue relative to the horizontal incisal tip were evaluated. A paired t-test and one-way analysis of variance were performed.Results:The upper incisors were retracted 5.76 mm and the lower incisors were retracted 4.62 mm (P < .001). The upper lip moved inferoposteriorly, and the lower lip moved superoposteriorly. In the lower lip, upward movement was greater than backward movement (P < .001). The most prominent changes appeared at the greatest bulge area. The relative ratios were 42%–53% in the upper lip area and 22%–82% in the lower lip area. The lip corners moved superoposteriorly (P < .001). Subnasale moved downward (P < .05) and posteriorly (P < .001), while the landmarks under the nostrils moved upward and posteriorly (P < .001).Conclusion:Facial scans from white structured light scanners efficiently evaluated 3D perioral soft tissue in dentoalveolar protrusion patients. Backward movement and significant vertical movement of the lip were observed. The nasal and lip angle areas showed considerable changes.     

全冠预备体终止线局部扫描正确度对整体的影响

目的: 探讨影响数字化印模中全冠预备体终止线扫描正确度的因素。方法: 在树脂牙列模型上制备右上第一磨牙标准全冠预备体,分别进行牙列内全冠预备体和孤立全冠预备体终止线的扫描正确度检测。牙列内全冠预备体终止线的扫描正确度检测:(1)应用Imetric扫描仪扫描全冠预备体,获得STL格式数据作为参考真值;(2)应用 CERE...     

脊柱胸腰段骨折椎体的三维形态学分析

目的 通过三维骨折线分布图的大数据形态学分析,揭示脊柱胸腰段椎体（T₁₁~L₂）骨折的好发模式及骨折特点,从而指导临床决策。方法 回顾性分析2017年1月至2019年3月AO分型为A型的压缩性胸腰段椎体（T₁₁~L₂）骨折病人的临床资料。共纳入了257例研究对象,平均年龄为46岁,266个骨折椎体,其中T₁₁骨折15例,T₁₂骨折69例,L₁骨折95例,L₂骨折87例。把病人高分辨率CT数据导入到Mimics软件中,通过阈值分割,重建出骨折椎体模型。依次将各个骨折椎体的骨折线临摹到相应正常椎体模型上,获得各个椎体节段的3D骨折线分布图。结果 3D骨折线分布图揭示骨折线主要集中在椎体的上半部分以及椎体的外1/3部分,并且沿着椎体的前方和侧方呈环状楔形分布。结论 首次将骨折的Mapping技术应用到胸腰段骨折的分析研究中,骨折线分布图揭示了胸腰段骨折的好发模式及形态学特点,从流行病学及形态学方面提高了对胸腰段骨折的认识,有助于提升后续的科学研究及改善临床决策。     

超声内镜和CT对食管癌术前分期的诊断价值

目的探讨超声内镜（EUS）和CT检查对食管癌术前分期的诊断价值。方法于2002年7月至2004年1月对51例食管癌手术患者行术前EUS和CT及术后病理检查，将EUS和CT分期结果和手术病理分期结果进行对照。结果（1）EUS检查T、N分期的准确率分别为82．4％（42／51）和88.0％（45／51）；CT检查T、N分期的准确率分别为52.9％（27／51）和51．0％（26／51）；EUS与CT联合检查T、N分期的准确率分别为86.3％（44／51）和90．2％（46／51）。（2）3种检查方式分期结果与病理分期结果的一致性统计结果：EUS检查T、N分期的Kappa分别为0．700（P〈0．001）和0．763（P〈0.001）；CT分别为0．275（P=0．002）和0．006（P=0.964）；EUS加CT则分别为0．769（P〈0.001）和0．801（P〈0.001）。（3）各组间差异的统计结果：EUS与CT比较，PT=0．001（X^2=10.079），PN〈0.001（X^2=16．730）；EUS加CT与EUS比较，PT=0.586（X^2=0．297），PN=0．750（X^2=0.102）。结论EUS对食管癌术前T、N分期诊断准确率较高，诊断价值优于CT；EUS与CT联合应用未能显著提高食管癌T、N分期的诊断准确率。