Pearls and pitfalls in magnetic resonance imaging of hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is the most common primary hepatic malignancy, which usually arises in cirrhotic liver. When the typical enhancement pattern, consisting of late arterial hyperenhancement followed by washout, is present in nodules larger than 1 cm, HCC can be confidently diagnosed without the need for tissue biopsy. Nevertheless, HCC can display an atypical enhancement pattern, either as iso or hypovascular lesion, or hypervascular lesion without washout. Not only the enhancement pattern of HCC could be atypical, but also a variety of histological types of HCC, such as steatotic, scirrhous, fibrolamellar, or combined hepatocellular-cholangiocellular carcinoma could raise diagnostic dilemmas. In addition, distinct morphological types of HCC or different growth pattern can occur. Awareness of these atypical and rare HCC presentations on magnetic resonance imaging is important for accurate differentiation from other focal liver lesions and timely diagnosis, which allows optimal treatment of patients.     

Improved dynamic connection detection power in estimated dynamic functional connectivity considering multivariate dependencies between brain regions

To estimate dynamic functional connectivity (dFC), the conventional method of sliding window correlation (SWC) suffers from poor performance of dynamic connection detection. This stems from the equal weighting of observations, suboptimal time scale, nonsparse output, and the fact that it is bivariate. To overcome these limitations, we exploited the kernel‐reweighted logistic regression (KELLER) algorithm, a method that is common in genetic studies, to estimate dFC in resting state functional magnetic resonance imaging (rs‐fMRI) data. KELLER can estimate dFC through estimating both spatial and temporal patterns of functional connectivity between brain regions. This paper compares the performance of the proposed KELLER method with current methods (SWC and tapered‐SWC (T‐SWC) with different window lengths) based on both simulated and real rs‐fMRI data. Estimated dFC networks were assessed for detecting dynamically connected brain region pairs with hypothesis testing. Simulation results revealed that KELLER can detect dynamic connections with a statistical power of 87.35% compared with 70.17% and 58.54% associated with T‐SWC (p‐value = .001) and SWC (p‐value <.001), respectively. Results of these different methods applied on real rs‐fMRI data were investigated for two aspects: calculating the similarity between identified mean dynamic pattern and identifying dynamic pattern in default mode network (DMN). In 68% of subjects, the results of T‐SWC with window length of 100 s, among different window lengths, demonstrated the highest similarity to those of KELLER. With regards to DMN, KELLER estimated previously reported dynamic connection pairs between dorsal and ventral DMN while SWC‐based method was unable to detect these dynamic connections.     

改良单图像法手工测量髌骨不稳患者胫骨结节-股骨滑车沟间距的可行性分析

目的 探讨改良单图像法手工测量髌骨不稳患者胫骨结节-股骨滑车沟（tibial tuberosity-trochlear groove，TT-TG）间距的可行性。 方法 选取髌骨不稳患者30例。高年资手术医师A、B，使用改良单图像法手工测量髌骨不稳患者TT-TG间距，对比高资年影像学医师C，使用双图法测量髌骨不稳患者TT-TG间距。应用Cronbach′s alpha系数评价结果的可信度。应用组内相关系数（intraclass correlation coefficient，ICC）评价结果的可重复性。使用Bland-Altman分析图评价结果的一致性。 结果 高年资手术医师A、B使用改良单图像法手工测量髌骨不稳患者TT-TG间距分别和高年资影像学医师C使用双图法测量髌骨不稳患者TT-TG间距比较，Cronbach′s alpha系数分别为0.913和0.959，组内相关系数分别为0.913和0.958。Bland-Altman分析图显示，TT-TG间距差值（mm）的均值为-0.276（95%CI：-3.526~2.974）和0.143（95%CI：-3.110~3.397）。A、B医师之间使用改良单图像法手工测量髌骨不稳患者TT-TG间距比较，Cronbach′s alpha系数为0.891，组内相关系数为0.891。Bland-Altman分析图显示TT-TG间距差值（mm）的均值为-0.276（95%CI：-3.526~2.974）。 结论 改良单图像法手工测量髌骨不稳患者TT-TG间距操作简单，可以准确测量出髌骨不稳患者的TT-TG间距，该方法和双图法可以相互替换使用。     

Accuracy of Conventional Periapical Radiography in Diagnosing Furcation Repair after Perforation Treatment

IntroductionPeriapical radiography (PR) is a diagnostic tool to be used by professionals in clinical practice. The method presents limitations, and doubts still exist about its value to evaluate furcation perforation and the reparative process of hard or soft tissues after treatment. Thus, the aim of this study was to evaluate the accuracy of PR as a diagnostic method to detect both resorption of the furcation area after induced experimental perforation and repair after perforation treatment using histopathological findings as a gold standard.MethodsThirty teeth of beagle dogs with furcation perforation were filled with Biodentine (Septodont, Saint-Maur-des-Fossés, France), ProRoot White mineral trioxide aggregate (Dentsply Tulsa Dental Specialties, Tulsa, OK), or gutta-percha and examined using PR and histology. Sensitivity, specificity, predictive values, and accuracy were calculated.ResultsPR detected repair and reabsorption of furcation perforation in 55% and 48% of the teeth, respectively. Histologic analysis showed furcation perforation in 66% and 21% of the teeth, respectively. Sensitivity and specificity of PR for the detection of repair were 0.84 and 1, respectively, whereas for resorption detection, the values were 0.43 and 0.65, respectively. Diagnostic accuracy for PR was 0.89 and 0.72 for repair and resorption of furcation perforation, respectively. PR showed more accurate diagnostic (true positives + true negatives/total) in repair detection compared with resorption of furcation perforation.ConclusionsWe conclude that PR is not adequate in detecting resorption progress after the treatment of furcation perforation, and we encourage the use of digital imaging when suspicious of a possible unsuccessful result after furcation perforation treatment.