BACKGROUND & AIMS: OBJECTIVE:Adnexal torsion is most commonly a clinical diagnosis, often aided by sonographic findings. At times, the clinical presentation can mimic nongynecologic causes of acute lower abdominal pain. In these cases, CT may be the initial imaging study. The purpose of this study was to define the CT features associated with adnexal torsion. CONCLUSION:On CT, a well-defined adnexal mass abnormally located in the pelvis with ipsilateral deviation of the uterus in a woman or girl with lower abdominal pain should raise the suspicion of adnexal torsion. Inflammatory signs on CT suggest the presence of necrosis.

背景与目标：

BACKGROUND & AIMS: OBJECTIVES:Iopentol (Nycomed Imaging AS, Oslo, Norway) and iopromide (Schering AG, Berlin, Germany) are low-osmolar, non-ionic, iodinated contrast media (CM) used in abdominal CT examinations. The intravenous safety profile and radiological efficacy of iopentol and iopromide were studied in 518 patients. Specifically, frequency of adverse events (AEs), subjective change in quality of diagnostic information, and quantitative enhancement characteristics were compared. MATERIALS AND METHODS:A prospective, double-blind, randomized, multicentre, parallel-group study was conducted at 8 hospitals. Patients received 100 ml of either iopentol 300 mg I/ml or iopromide 300 mg I/ml. RESULTS:The incidence of patients with AEs was statistically significantly lower in the iopentol group compared to the iopromide group (2.3% vs. 8.9%, p < 0.001). Discomfort was frequent in both groups (44.8% vs. 49.4%, p = 0.33), sensation of heat and warmth being most common. Overall, diagnostic information was similar in both groups. Both CM gave high percentages of examinations rated as optimal (87.1% vs. 90.5%, p = 0.34) and in which diagnostic confidence was increased (87.5% vs. 91.1%, p = 0.22). No significant differences between the two CM were found concerning quantitative enhancement characteristics. CONCLUSIONS:In this study iopentol was significantly safer than iopromide for contrast enhanced CT examination of the abdomen. Radiological efficacy was similar with both CM.

背景与目标：

BACKGROUND & AIMS: OBJECTIVE:The objective of our study was to evaluate whether 0.3-second cine CT can be used to detect air trapping in the lungs of young children. SUBJECTS AND METHODS:In 30 children (mean age, 25 months), 0.3-second cine CT was performed at six levels during 3 seconds of quiet breathing. The study population was divided into an air trapping group (n = 24) and a no-air trapping group (n = 6). Lung density was measured at an abnormal area (with or without air trapping) and an adjacent normal area on inspiratory and expiratory phase images. Lung density differences between inspiration and expiration were calculated and compared in abnormal areas (with or without air trapping) and in normal areas. Their percentages were calculated and compared between the two groups. In addition, lung density differences between abnormal and adjacent normal areas were calculated and compared between the two groups. RESULTS:Lung density differences between inspiration and expiration were smaller in areas with air trapping (mean +/- SD, -19 +/- 34 H) than in abnormal areas without air trapping (138 +/- 36 H) (p < 0.001) or in normal areas (111 +/- 49 H) (p < 0.001). Their percentages were smaller in the group with air trapping (-27% +/- 54%) than in the group with no air trapping (120% +/- 87%) (p < 0.001). In the group with air trapping, lung density differences were larger at the expiratory phase (260 +/- 77 H) than at the inspiratory phase (129 +/- 69 H) (p < 0.001), but did not change through the respiratory cycle in the group with no air trapping (p > 0.05). CONCLUSION:Air trapping can be accurately detected in the lungs of free-breathing young children using 0.3-second cine CT.

背景与目标：

BACKGROUND & AIMS: :Calcium oxalate monohydrate (COM) stones are often resistant to breakage using shock wave (SW) lithotripsy. It would be useful to identify by computed tomography (CT) those COM stones that are susceptible to SW's. For this study, 47 COM stones (4-10 mm in diameter) were scanned with micro CT to verify composition and also for assessment of heterogeneity (presence of pronounced lobulation, voids, or apatite inclusions) by blinded observers. Stones were then placed in water and scanned using 64-channel helical CT. As with micro CT, heterogeneity was assessed by blinded observers, using high-bone viewing windows. Then stones were broken in a lithotripter (Dornier Doli-50) over 2 mm mesh, and SW's counted. Results showed that classification of stones using micro CT was highly repeatable among observers (kappa = 0.81), and also predictive of stone fragility. Stones graded as homogeneous required 1,874 +/- 821 SW/g for comminution, while stones with visible structure required half as many SW/g, 912 +/- 678. Similarly, when stones were graded by appearance on helical CT, classification was repeatable (kappa = 0.40), and homogeneous stones required more SW's for comminution than did heterogeneous stones (1,702 +/- 993 SW/g, compared to 907 +/- 773). Stone fragility normalized to stone size did not correlate with Hounsfield units (P = 0.85). In conclusion, COM stones of homogeneous structure require almost twice as many SW's to comminute than stones of similar mineral composition that exhibit internal structural features that are visible by CT. This suggests that stone fragility in patients could be predicted using pre-treatment CT imaging. The findings also show that Hounsfield unit values of COM stones did not correlate with stone fragility. Thus, it is stone morphology, rather than X-ray attenuation, which correlates with fragility to SW's in this common stone type.

背景与目标： : 草酸钙一水合物 (COM) 结石经常使用休克 (SW) 碎石术抵抗破裂。通过计算机断层扫描 (CT) 识别易受SW影响的COM结石将很有用。对于这项研究，用micro CT扫描了47个COM结石 (直径4-10毫米)，以验证成分，并通过盲观察者评估异质性 (明显的分叶，空隙或磷灰石内含物的存在)。然后将结石放入水中，并使用64通道螺旋ct扫描。与micro CT一样，盲观察者使用高骨观察窗评估异质性。然后，石头在碎石机 (Dornier Doli-50) 中破碎了2毫米个网格，并计算了SW。结果表明，使用micro CT对结石进行分类在观察者中具有很高的重复性 (kappa = 0.81)，并且还可以预测结石的脆性。将石头分级为均匀所需的1,874 +/- 821 SW/g进行粉碎，而具有可见结构的石头需要一半的SW/g，912 +/- 678。同样，当通过螺旋ct上的外观对结石进行分级时，分类是可重复的 (kappa = 0.40)，并且均质结石比异质结石需要更多的SW进行粉碎 (1,702 +/- 993 SW/g，而907 +/- 773)。标准化为石头大小的石头脆性与Hounsfield单位不相关 (P = 0.85)。总之，均质结构的COM石需要粉碎的SW几乎是具有类似矿物成分的石的两倍，这些矿物成分具有CT可见的内部结构特征。这表明可以使用治疗前的CT成像来预测患者的结石脆性。研究结果还表明，COM石的Hounsfield单位值与石的脆弱性无关。因此，在这种常见的石头类型中，与脆性相关的是石头形态，而不是x射线衰减。

BACKGROUND & AIMS: AIM:To observe the effect of targeted therapy with 64-slice spiral computed tomography (CT) combined with cryoablation for liver cancer. METHODS:A total of 124 patients (142 tumors) were enrolled into this study. According to the use of dual-slice spiral CT or 64-slice spiral CT as a guide technology, patients were divided into two groups: dual-slice group (n = 56, 65 tumors) and 64-slice group (n = 8, 77 tumors). All patients were accepted and received targeted therapy by an argon-helium superconducting surgery system. The guided scan times of the two groups was recorded and compared. In the two groups, the lesion ice coverage in diameter of ≥ 3 cm and < 3 cm were recorded, and freezing effective rate was compared. Hepatic perfusion values [hepatic artery perfusion (HAP), portal vein perfusion (PVP), and the hepatic arterial perfusion index (HAPI)] of tumor tissues, adjacent tissues and normal liver tissues at preoperative and postoperative four weeks in the two groups were compared. Local tumor changes were recorded and efficiency was compared at four weeks post-operation. Adverse events were recorded and compared between the two groups, including fever, pain, frostbite, nausea, vomiting, pleural effusion and abdominal bleeding. RESULTS:Guided scan times in the dual-slice group was longer than that in the 64-slice group (t = 11.445, P = 0.000). The freezing effective rate for tumors < 3 cm in diameter in the dual-slice group (81.58%) was lower than that in the 64-slice group (92.86%) (χ2 = 5.707, P = 0.017). The HAP and HAPI of tumor tissues were lower at four weeks post-treatment than at pre-treatment in both groups (all P < 0.05), and those in the 64-slice group were lower than that in the dual-slice group (all P < 0.05). HAP and PVP were lower and HAPI was higher in tumor adjacent tissues at post-treatment than at pre-treatment (all P < 0.05). Furthermore, the treatment effect and therapeutic efficacy in the dual-slice group were lower than the 64-slice group at four weeks post-treatment (all P < 0.05). Moreover, pleural effusion and intraperitoneal hemorrhage occurred in patients in the dual-slice group, while no complications occurred in the 64-slice group (all P < 0.05). CONCLUSION:64-slice spiral CT applied with cryoablation in targeted therapy for liver cancer can achieve a safe and effective freezing treatment, so it is worth being used.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:CT radiation dose reduction results in increased noise or graininess of images which affects the diagnostic information. One of the approaches to lower radiation exposure to patients is to reduce image noise with the use of image processing software in low radiation dose images. PURPOSE:To assess image quality and accuracy of non-linear adaptive filters (NLAF) at low dose chest CT. MATERIAL AND METHODS:In an IRB approved prospective study, 24 patients (mean age, 63 ± 7.3 years; M:F ratio, 11:13) gave informed consent for acquisition of four additional chest CT image series at 150, 110, 75, and 40 mAs (baseline image series) on a 64-slice MDCT over an identical 10-cm length. NLAF was used to process three low dose (110, 75, and 40 mAs) image series (postprocessed image series). Two radiologists reviewed baseline and postprocessed images in a blinded manner for image quality. Objective noise, CT attenuation values, patient weight, transverse diameters, CTDIvol, and DLP were recorded. Statistical analysis was performed using parametric and non-parametric tests for comparing postprocessed and baseline images. RESULTS:No lesions were missed on baseline or postprocessed CT images (n = 80 lesions, 73 lesions <1 cm). At 40 mAs, subjective noise in mediastinal window settings were graded as unacceptable in baseline images and acceptable in postprocessed images. Visibility of smaller structures improved from suboptimal visibility in baseline images at 40 mAs to excellent in postprocessed images at 40 mAs. No major artifacts were seen due to NLAF postprocessing, except for minor beam hardening artifacts not affecting diagnostic decision-making (14/22) in both baseline and postprocessed image series. Diagnostic confidence for chest CT was improved to fully confident in postprocessed images at 40 mAs. Compared to baseline images, postprocessing reduced objective noise by 26% (14.2 ± 4.7/19.2 ± 6.4), 31.5% (15.2 ± 4.7/22.2 ± 5.7), and 41.5% (16.9 ± 6/28.9 ± 10.2) at 110 mAs, 75 mAs, and 40 mAs tube current-time product levels. CONCLUSION:Applications of NLAF can help reduce tube current down to 40 mAs for chest CT while maintaining lesion conspicuity and image quality.

背景与目标：

BACKGROUND & AIMS: :Neuroimaging after a first unprovoked seizure may show significant abnormalities. In our study, 32% of all children with a first apparent unprovoked seizure had an abnormal CT scan result. Most of these were ring-enhancing lesions of cysticercal or tubercular origin.

背景与目标： : 第一次无缘无故癫痫发作后的神经影像学可能显示出明显的异常。在我们的研究中，所有首次出现明显的无端癫痫发作的儿童中有32% 的ct扫描结果异常。其中大多数是囊尾或结核起源的环增强病变。

BACKGROUND & AIMS: :Percutaneous transluminal coronary angioplasty (PTCA) with stent implantation is widely used for the treatment of coronary stenosis. However, restenosis after stent implantation frequently reported by intravascular ultrasound evaluation. This may occur because of the reduced luminal area after implantation, insufficient stent expansion, or by the elastic recoil of the stent (ERS). Quantitative evaluation of stent expanding should provide further information on how to decrease the incidence of re-stenosis. Many previous studies have observed stent properties in 2D. However, the stent geometry is changed in 3D space, and 3D measurements will provide further information on factors such as the risk for asymmetric ERS. We performed 3D reconstruction using high spatial resolution images obtained with a Micro-CT system to observe the 3D expansion behavior of a test stent and quantitatively evaluate ERS. The expansion behavior of each structural component of the stent varied, as did the ERS and eccentricity. ERS ranged from 2.4% to 9.2% during observation form proximal and distal positions in each component. The greatest difference in ERS between 2D and 3D measurements was 5.2%. 3D measurements provide more information on ERS than 2D measurements. Our result shows the importance of the observation, and the evaluation by three dimensions.

背景与目标： : 经皮冠状动脉腔内成形术 (PTCA) 与支架植入术广泛用于治疗冠状动脉狭窄。然而，血管内超声评估经常报告支架植入后的再狭窄。这可能是由于植入后管腔面积减小，支架扩张不足或支架的弹性反冲 (ERS) 引起的。支架扩张的定量评估应提供有关如何减少再狭窄发生率的进一步信息。以前的许多研究都在2D中观察到了支架的特性。但是，支架的几何形状在3D空间中会发生变化，并且3D测量将提供有关诸如不对称ERS风险等因素的进一步信息。我们使用Micro-CT系统获得的高空间分辨率图像进行了3D重建，以观察测试支架的3D扩展行为并定量评估ERS。支架的每个结构组件的膨胀行为以及ERS和偏心率都有所不同。在观察期间，每个组件的近端和远端位置的ERS范围从2.4% 到9.2%。2D和3D测量之间的ERS的最大差异是5.2%。3D测量比2D测量提供更多关于ERS的信息。我们的结果显示了观察的重要性，并通过三个维度进行了评估。

BACKGROUND & AIMS: BACKGROUND:Posttraumatic anterior shoulder instability is associated with anterior glenoid bone loss, contributing to recurrence. Accurate preoperative quantification of bone loss is paramount to avoid failure of a soft tissue stabilization procedure as bone reconstruction is recommended for glenoid defects greater than 20% to 27%. QUESTIONS/PURPOSES:We determined whether radiography, MRI, or CT was most reliable to quantify glenoid bone loss in recurrent anterior shoulder instability. METHODS:Seven intact fresh-frozen human cadaveric shoulders were imaged with radiography, MRI, CT, and three-dimensional (3-D) CT. Three sequential anterior glenoid defects then were created, measured, and the shoulders reimaged after each defect. Defect sizes were less than 12%, 12% to 25%, and 25% to 40%. The gold standard measurement was determined by comparing measurements taken on the cadaver by two surgeons using digital calipers with the measurements determined by using electronic digital calipers on the 3-D CT. This measurement was used for comparison of all estimations by the evaluators. Twelve independent blinded evaluators reviewed the 112 image sets and estimated the percent of glenoid bone loss. Images were scrambled and rereviewed by the same observers 2 months later to determine intraobserver reliability. We determined reliability with kappa values. RESULTS:Kappa values between predicted bone loss versus true loss (determined by our gold standard measurements) across all 12 raters for each modality were: 3-D CT, 0.50; CT, 0.40; MRI, 0.27; and radiographs, 0.15. Interobserver agreement (kappa) values were: 3-D CT, 0.54; CT, 0.47; MRI, 0.31; and radiographs, 0.15. The intraobserver agreement (kappa) values were: 3-D CT, 0.59; CT, 0.64; MRI, 0.51; and radiographs, 0.45. CONCLUSIONS:Three-dimensional CT was the most reliable imaging modality for predicting glenoid bone loss. Regular CT was the second most reliable and reproducible modality.

背景与目标：

BACKGROUND & AIMS: OBJECTIVE:To investigate the characteristics of epidemiological distribution of the ossification of the ligamentum flavum (OLF) in the thoracic spine including the incidence, segmental distribution, and shape. METHODS:Chest spiral computed tomography scans of 993 cases (male 506, female 487, mean age 60 years, range 5-102 years) who presented due to chest symptoms were analyzed with axial slices combined with sagittal slices. The conditions of OLF in the thoracic spine, including segments, thickness, location, and dural sac compression, were recorded. Prevalence was standardized according to the "Age Structure of Population in Beijing 2008". RESULTS:Among the population investigated, the standardized prevalence rate was 63.9 %. The standardized prevalence rate for males (68.5 %) was higher than that for females (59.0 %). The highest prevalence rate of OLF was in the 50-59 years age group (79.2 %); however, high density originated it can be found in individuals aged 10-19 years. The comparison of different thoracic segments showed that T10-11 (44.0 %) and T11-12 (41.6 %) had the highest prevalence rates. CONCLUSION:The prevalence of ossification of the ligamentum flavum was highest in the 50-59 years group, but also occurred in early years. OLF occurs more frequently in the lower than in the upper and middle thoracic regions and its prevalence increases with aging.

背景与目标：

BACKGROUND & AIMS: OBJECTIVES:Performance evaluation of a fully automated system for calculating computed tomography (CT) coronary artery calcium scores from contrast medium-enhanced coronary CT angiography (cCTA) studies. METHODS:One hundred and twenty-seven patients (58 ± 11 years, 71 men) who had undergone cCTA as well as an unenhanced CT calcium scoring study where included. Calcium scores were computed from cCTA by an automated image processing algorithm and compared with calcium scores obtained by standard manual assessment of unenhanced CT calcium scoring studies. Results were compared vis-a-vis (1) absolute calcium score values, (2) age-, gender- and race-dependent percentiles, and (3) commonly used calcium score risk classification categories. RESULTS:One hundred and nineteen out of 127 (93.7%) studies were successfully processed. Mean Agatston calcium score values obtained by traditional non-contrast CT calcium scoring studies and derived from contrast medium-enhanced cCTA did not significantly differ (235.6 ± 430.5 vs 262.0 ± 499.5; P > 0.05). Calcium score risk categories and Multi-Ethnic Study of Atherosclerosis (MESA) percentiles showed very high correlation (Spearman rank correlation coefficient = 0.97, P < 0.0001/0.95, P < 0.0001) between the two approaches. CONCLUSIONS:Calcium score values automatically computed from cCTA are highly correlated with standard unenhanced CT calcium scoring studies. These results suggest a radiation dose- and time-saving potential when deriving calcium scores from cCTA studies without a preceding unenhanced CT calcium scoring study.

背景与目标：

BACKGROUND & AIMS: OBJECTIVE:The visceral fat area (VFA) was measured, and the relationships between the VFA and the body mass index (BMI), waist circumference, blood pressure, and indices of lipid and sugar metabolism were evaluated. METHODS:The subjects included 607 consecutive patients who underwent VFA examinations using computed tomography (CT) scans. In addition to the routine examination parameters, the levels of adiponectin and homeostasis model assessment as an index of insulin resistance (HOMA-IR) were measured in all subjects, and the levels of malondialdehyde-modified low-density lipoprotein (MDA-LDL), remnant-like particles (RLP), lipoprotein (a) (Lp(a)), apolipoprotein (Apo) AI, ApoB and ApoE were measured in 270 subjects. RESULTS:In both men and women, the VFA showed significant positive correlations with the age, BMI, waist circumference, subcutaneous fat area, visceral fat area/subcutaneous fat area (v/s) ratio, systolic blood pressure, diastolic blood pressure, the fasting blood sugar (FBS), the hemoglobin A1c (HbA1c), high-density lipoprotein cholesterol (HDLC), triglyceride (TG), uric acid, HOMA-IR and ApoB and the ApoB/LDLC ratio and significant negative correlations with the levels of HDLC and adiponectin. The levels of the total cholesterol (TC), low-density lipoprotein cholesterol (LDLC), non-HDLC, MDA-LDL and Lp(a) and the ApoB/ApoAI ratio were not correlated with the VFA in either men or women. The RLP exhibited a significant positive correlation with the VFA in women. CONCLUSION:The VFA exhibited high positive correlations with the waist circumference, blood pressure and TG level and a negative correlation with the HDLC level, regardless of gender, supporting the validity of the present diagnostic method for evaluating metabolic syndrome (MS). Although the LDLC level is not included in the diagnostic criteria for MS, the positive correlations between the VFA and the ApoB level and ApoB/LDLC ratio observed in both men and women indicate qualitative abnormalities of lipoproteins, such as an increase in the amount of small dense LDL. Measuring the levels of apolipoproteins in addition to lipoproteins during health screening is therefore useful for evaluating of atherogenicity.

背景与目标：

BACKGROUND & AIMS: :The diagnosis and treatment of pneumothorax in patients with complex cystic lung disease may be difficult when relying on plain chest radiography alone. We report four cases in which management was greatly facilitated by the use of CT scanning of the chest.

背景与目标： : 单纯依靠胸部平片检查，复杂囊性肺疾病患者气胸的诊断和治疗可能会很困难。我们报告了4例病例，其中使用胸部ct扫描极大地促进了治疗。

BACKGROUND & AIMS: :OBJECTIVE Spinal navigation techniques for surgical fixation of unstable C1-2 pathologies are challenged by complex osseous and neurovascular anatomy, instability of the pathology, and unreliable preoperative registration techniques. An intraoperative CT scanner with autoregistration of C-1 and C-2 promises sufficient accuracy of spinal navigation without the need for further registration procedures. The aim of this study was to analyze the accuracy and reliability of posterior C1-2 fixation using intraoperative mobile CT scanner-guided navigation. METHODS In the period from July 2014 to February 2016, 10 consecutive patients with instability of C1-2 underwent posterior fixation using C-2 pedicle screws and C-1 lateral mass screws, and 2 patients underwent posterior fixation from C-1 to C-3. Spinal navigation was performed using intraoperative mobile CT. Following navigated screw insertion in C-1 and C-2, intraoperative CT was repeated to check for the accuracy of screw placement. In this study, the accuracy of screw positioning was retrospectively analyzed and graded by an independent observer. RESULTS The authors retrospectively analyzed the records of 10 females and 2 males, with a mean age of 80.7 ± 4.95 years (range 42-90 years). Unstable pathologies, which were verified by fracture dislocation or by flexion/extension radiographs, included 8 Anderson Type II fractures, 1 unstable Anderson Type III fracture, 1 hangman fracture Levine Effendi Ia, 1 complex hangman-Anderson Type III fracture, and 1 destructive rheumatoid arthritis of C1-2. In 4 patients, critical anatomy was observed: high-riding vertebral artery (3 patients) and arthritis-induced partial osseous destruction of the C-1 lateral mass (1 patient). A total of 48 navigated screws were placed. Correct screw positioning was observed in 47 screws (97.9%). Minor pedicle breach was observed in 1 screw (2.1%). No screw displacement occurred (accuracy rate 97.9%). CONCLUSION Spinal navigation using intraoperative mobile CT scanning was reliable and safe for posterior fixation in unstable C1-2 pathologies with high accuracy in this patient series.

背景与目标： : 目的脊柱导航技术用于手术固定不稳定的C1-2病理受到复杂的骨和神经血管解剖，病理的不稳定性以及不可靠的术前配准技术的挑战。具有C-1和C-2自动注册的术中CT扫描仪保证了脊柱导航的足够准确性，而无需进一步的注册程序。这项研究的目的是分析使用术中移动CT扫描仪引导的导航进行后路C1-2固定的准确性和可靠性。方法2014年7月至2016年2月连续10例C1-2不稳患者采用C-2椎弓根螺钉和C-1侧块螺钉进行后路固定，C-1至C-3 2例后路固定。使用术中移动CT进行脊柱导航。在C-1和C-2中导航螺钉插入后，重复术中CT以检查螺钉放置的准确性。在这项研究中，由独立的观察者对螺钉定位的准确性进行了回顾性分析和评分。结果作者回顾性分析了10名女性和2名男性的记录，平均年龄为80.7 ± 4.95岁 (42-90岁)。通过骨折脱位或屈伸x线片证实的不稳定病理包括8例安德森II型骨折，1例不稳定安德森III型骨折，1例hangman骨折Levine Effendi Ia，1例复杂hangman-Anderson III型骨折和1例破坏性C1-2类风湿性关节炎。在4例患者中，观察到重要的解剖结构: 高位椎动脉 (3例) 和关节炎引起的C-1侧块的部分骨性破坏 (1例)。总共放置了48个导航螺钉。在47个螺钉 (97.9%) 中观察到正确的螺钉定位。在1个螺钉 (2.1%) 中观察到轻微的椎弓根破裂。没有螺杆位移发生 (准确率97.9%)。结论在不稳定的C1-2病变中，使用术中移动ct扫描进行脊柱导航是可靠且安全的，在该系列患者中准确性较高。

BACKGROUND & AIMS: AIM:To explore in a laboratory setting the feasibility of using Meglumine Diatrizoate (MD) to improve the accuracy of diagnosis of cracked teeth on cone-beam CT (CBCT) images. METHODOLOGY:Twenty-four teeth were cracked artificially by soaking them cyclically in liquid nitrogen and hot water. The number and position of crack lines were evaluated with a dental operating microscope and used as the gold standard. The artificially cracked teeth were then examined using routine scanning (RS) and enhanced scanning (ES) modes, respectively. For the ES mode, MD was painted on the surface of the crack lines, and then, CBCT scanning with the same parameters was performed after 10 min. A radiological graduate student and an experienced radiologist evaluated the presence or absence of crack lines, respectively. The differences between the RS and ES modes were determined and assessed using McNemar's test. Inter-examiner agreement and intra-examiner agreement were assessed using kappa analysis. RESULTS:Fifty-seven crack lines were found in the 24 cracked teeth. In the RS mode, the accuracy of detection of crack lines was 23% (radiological graduate student) and 32% (experienced radiologist), whereas in the ES mode, the accuracy was 61% (radiological graduate student) and 65% (experienced radiologist). The inter-examiner agreement was 0.693 in RS mode and 0.849 in ES mode. The intra-examiner agreement was 0.872 and 0.949 for the radiological graduate student in RS and ES mode respectively; and one for the experienced radiologist both in RS and ES mode. CONCLUSIONS:Compared with routine scanning mode, more crack lines could be detected in enhanced scanning mode using Meglumine Diatrizoate as a contrast medium. MD could be a potential contrast medium to improve the accuracy of detection of crack lines on CBCT images.

背景与目标：