Spectral Computed Tomography: Fundamental Principles and Recent Developments

CT is a diagnostic tool with many clinical applications. The CT voxel intensity is related to the magnitude of X-ray attenuation, which is not unique to a given material. Substances with different chemical compositions can be represented by similar voxel intensities, making the classification of different tissue types challenging. Compared to the conventional single-energy CT, spectral CT is an emerging technology offering superior material differentiation, which is achieved using the energy dependence of X-ray attenuation in any material. A specific form of spectral CT is dual-energy imaging, in which an additional X-ray attenuation measurement is obtained at a second X-ray energy. Dual-energy CT has been implemented in clinical settings with great success. This paper reviews the theoretical basis and practical implementation of spectral/dual-energy CT.     

Effects of 3D image-guided brachytherapy compared to 2D conventional brachytherapy on clinical outcomes in patients with cervical cancer: A systematic review and meta-analyses

PURPOSETo assess the effects of three-dimensional image-guided brachytherapy (3D BT) compared to bi-dimensional BT (2D BT) on clinical outcomes in patients with cervical cancer.METHODS AND MATERIALSWe searched PubMed/MEDLINE, EMBASE, Scopus, CENTRAL, Web of Science, and LILACS for studies assessing the effects of 3D BT versus 2D BT on clinical outcomes. Two reviewers independently screened retrieved citations, extracted data and assessed risk of bias from eligible studies. Hazard ratios (HR) were calculated from Kaplan-Meier curves considering the number of events, their timing and the followup of censored patients. We conducted meta-analyses of HR using the inverse-variance random-effects method. Risk Difference (RD) for toxicities were pooled using the Mantel–Haenszel random-effects method. We used the GRADE system to rate the certainty of evidence.RESULTSTwenty observational studies involving 4287 patients were included. The meta-analyses assessing the effect of 3D BT versus 2D BT on overall survival resulted in a HR of 0.78 (95%CI 0.62–0.98), HR of 0.75 (95%CI 0.62–0.90) for pelvic disease-free survival, HR of 0.93 (95%CI 0.81–1.06) for metastatic disease-free survival, and HR of 0.77 (95%CI 0.59–0.99) for local control. Grade 3–4 global and gastrointestinal toxicities were, respectively, 9% lower (95%CI 6% to 11%) and 5% lower (95%CI 2% to 8%) in patients receiving 3D BT versus 2D BT. Certainty of evidence was very low for all assessed outcomes.CONCLUSIONSOur study may suggest a benefit of 3D BT over conventional 2D BT on important clinical outcomes.     

Antibiotic prescribing in patients with COVID-19: rapid review and meta-analysis

BackgroundThe proportion of patients infected with SARS-CoV-2 that are prescribed antibiotics is uncertain, and may contribute to patient harm and global antibiotic resistance.ObjectiveThe aim was to estimate the prevalence and associated factors of antibiotic prescribing in patients with COVID-19.Data SourcesWe searched MEDLINE, OVID Epub and EMBASE for published literature on human subjects in English up to June 9 2020.Study Eligibility CriteriaWe included randomized controlled trials; cohort studies; case series with ≥10 patients; and experimental or observational design that evaluated antibiotic prescribing.ParticipantsThe study participants were patients with laboratory-confirmed SARS-CoV-2 infection, across all healthcare settings (hospital and community) and age groups (paediatric and adult).MethodsThe main outcome of interest was proportion of COVID-19 patients prescribed an antibiotic, stratified by geographical region, severity of illness and age. We pooled proportion data using random effects meta-analysis.ResultsWe screened 7469 studies, from which 154 were included in the final analysis. Antibiotic data were available from 30 623 patients. The prevalence of antibiotic prescribing was 74.6% (95% CI 68.3–80.0%). On univariable meta-regression, antibiotic prescribing was lower in children (prescribing prevalence odds ratio (OR) 0.10, 95% CI 0.03–0.33) compared with adults. Antibiotic prescribing was higher with increasing patient age (OR 1.45 per 10 year increase, 95% CI 1.18–1.77) and higher with increasing proportion of patients requiring mechanical ventilation (OR 1.33 per 10% increase, 95% CI 1.15–1.54). Estimated bacterial co-infection was 8.6% (95% CI 4.7–15.2%) from 31 studies.ConclusionsThree-quarters of patients with COVID-19 receive antibiotics, prescribing is significantly higher than the estimated prevalence of bacterial co-infection. Unnecessary antibiotic use is likely to be high in patients with COVID-19.     

State and Trait Anxiety of Adolescents with Autism Spectrum Disorders

Objective This study examined how state and trait anxiety of adolescents with autism spectrum disorders (ASD) are associated with their demographic characteristics, repetitive and restricted behaviors (RRBs), and internalizing and externalizing problem behaviors. Methods A total of 96 participants with ASD (mean age=14.30 years; 91 males) completed a battery of tests including the State/Trait Anxiety Inventory (STAI), the Autism Diagnostic Interview-Revised, the Social Responsiveness Scale (SRS), and a cognitive test measuring intelligence quotient (IQ). Participants’ parents completed the Child Behavior Checklist (CBCL). Pearson’s correlations among age, IQ, two subscales of the STAI (i.e., STAIS and STAIT, measuring self-reported state and trait anxiety, respectively), and the Anxiety subscale of CBCL (i.e., CBCL-Anxiety, measuring parent-reported trait anxiety) were computed. Subsequently, Pearson’s correlations were computed among the three anxiety measures, RRBs, and problem behaviors, while controlling for participants’ age and IQ. Results The STAIS and CBCL-Anxiety were both significantly correlated with higher age, sensory sensitivity, depressive symptoms, somatic complaints, and aggressive behaviors. All three anxiety variables were significantly and positively correlated with total SRS RRB scores. Additionally, the STAIS and STAIT were significantly associated with more severe Compulsion/Adherence behaviors, and the CBCL-Anxiety was also significantly associated with more severe Rule-breaking Behaviors. Conclusion Self-reported state anxiety showed association patterns similar to those of parent-reported trait anxiety. Future studies investigating the precise operationalization of different anxiety instruments are needed to accurately measure the anxiety of adolescents with ASD.     

Prognostic Significance of Ror2 and Wnt5a Expression in Medulloblastoma

Medulloblastoma (MB) is a clinically and biologically heterogeneous group of tumors, and currently classified into four molecular subgroups (Wnt, Shh, Group 3 and Group 4). Intracellular signaling of the Wnt pathway has been divided into two classes: the “canonical” and the “non‐canonical” signaling pathway. The canonical signaling pathway is a well‐established, β‐catenin‐dependent signaling pathway in MB. In contrast, very little research about the non‐canonical WNT signaling pathway in MB exists. In order to identify the roles of Wnt‐5a and Ror2, two non‐canonical WNT pathway‐related genes, we studied 76 cases of MB with immunohistochemistry and quantitative real‐time PCR and correlated the results with clinicopathological and other molecular parameters and prognosis. Wnt5a and Ror2 were immunopositive in 20 (29.4%) and 35 (51.5%) of 68 cases, respectively. There were positive associations among protein expressions of Wnt5a, Ror2 and β‐catenin. Ror2 mRNA levels were well correlated with immunoexpression. Ror2 mRNA expression was significantly associated with CTNNB1 mutation. High Ror2 mRNA expression was an independent favorable prognostic factor. In conclusion, our study demonstrates the first attempt to identify Wnt5a and Ror2 as additional mechanisms contributing to dysregulation of the non‐canonical WNT signaling pathway in MB. Ror2 may play a role as an oncosuppressor in MB.     

Longest neurite‐specific activation of Rap1B in hippocampal neurons contributes to polarity formation through RalA and Nore1A in addition to PI3‐kinase

In a developing nervous system, axon‐dendrite formation is instructed by extrinsic cues, and the mechanism whereby a developing neuron interprets these cues using intracellular signaling is particularly important. Studies using dissociated hippocampal neurons have identified many signaling pathways underlying neuronal polarization. Among the components of these pathways, Rap1B is essential for axon specification in hippocampal cultures. However, spatiotemporal regulation of Rap1B activity in polarizing neurons and how it affects neuronal polarization remain unclear. Herein, we investigated spatiotemporal activity‐change of Rap1B and its target molecules in hippocampal neurons. FRET imaging showed that specific activation of Rap1B was observed at the tip of a future axon. To dissect downstream signaling, we used three effector mutants of Rap1B. Expression of Rap1B‐G12V/E37G and G12V/Y40C mutants resulted in supernumerary axons. The targets of Rap1B‐G12V/E37G were RalA and Nore1A, whereas Rap1B‐G12V/Y40C activated PI3‐kinase. RalA was activated in the tip of stage 3 axons, and RalA‐S28N expression reduced the fraction of neurons with supernumerary axons induced by Rap1B‐G12V/E37G. Furthermore, Nore1A depletion reduced the number of cells without axons. These results indicate that specific activation of Rap1B contributes to neuronal polarization via interaction with RalA and Nore1A in addition to PI3‐kinase.     

The usefulness of the three-dimensional enhanced T1 high-resolution isotropic volume excitation MR in the evaluation of shoulder pathology: comparison with two-dimensional enhanced T1 fat saturation MR

Objective:

To evaluate the diagnostic accuracy of three-dimensional (3D) enhanced T₁ high-resolution isotropic volume excitation (eTHRIVE) shoulder MR for variable shoulder pathology such as rotator cuff tear, labral injury and synovial pathology in comparison with two-dimensional enhanced fast spin echo T₁ fat saturation (2D T1 FS) sequences MR.

Methods:

This retrospective study included 86 patients who underwent MRI of the shoulder using eTHRIVE technique. Two radiologists evaluated anatomic identification of the supraspinatus, glenoid labrum and acromioclavicular joint (AC joint) on routine MRI sequences (2D T1 FS) and compared them with the reformatted eTHRIVE images. Subjective scoring of the images was performed with a four-point scale that rated the degree of discrimination of the shape of the supraspinatus, glenoid labrum and AC joint. The diagnostic accuracy of eTHRIVE compared with routine MR images was evaluated in terms of rotator cuff pathology, labral pathology and synovial pathology.

Results:

Anatomic identification scores of the supraspinatus tendon and labrum were significantly lower for eTHRIVE than for 2D T1 FS. There were no significant differences between eTHRIVE and 2D T1 FS in anatomic identification of the AC joint. There were no significant differences between eTHRIVE and 2D T1 FS in diagnosing the three disease categories.

Conclusion:

eTHRIVE had comparable diagnostic accuracy to 2D T1 FS imaging in the evaluation of rotator cuff tears, labral injury and synovial pathology, but anatomic identification was inferior to that of 2D T1 FS.

Advances in knowledge:

The accuracy of 3D eTHRIVE imaging is comparable to that of 2D T1 FS for the diagnosis of rotator cuff tears, labral injury and synovial pathology.     

Bone Tunnel Diameter Measured with CT after Anterior Cruciate Ligament Reconstruction Using Double-Bundle Auto-Hamstring Tendons: Clinical Implications

ObjectiveTo evaluate the correlation between bone tunnel diameter after anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and stability or clinical scores.ResultsThe tibial bone tunnels for the anteromedial bundles were significantly widened at T2 compared with T1 (observer 1, 0.578 mm to 0.698 mm, p value of < 0.001; observer 2, 0.581 mm to 0.707 mm, p value of < 0.001). There was no significant correlation between the diameter at T2 and stability or clinical scores and between the interval change ratio ([T2 - T1] / T1) and stability or clinical scores (corrected p values for all were 1.0). Intraobserver agreement for measurements was excellent (> 0.8) for both observers. Interobserver agreement for measurement was excellent (> 0.8) except for the most distal portion of the femoral bone tunnel for anterior medial bundle in immediate postoperative CT, which showed moderate agreement (concordance correlation coefficient = 0.6311).ConclusionNeither the diameter nor its change ratio during interval follow-up is correlated with stability or clinical scores.