Are ADC histogram metrics repeatable?

Purpose: The present study evaluated the repeatability of apparent diffusion coefficient (ADC) histogram metrics in clinical MRI.Methods: Twelve patients who underwent head MRI in our hospital from May to July in 2016 were included in the present study. All patients gave informed consent. Two sequential diffusion-weighted images with echo planar imaging (DWI-EPI) in the identical positioning were obtained. The b-factors of 0 and 1000 or 1500 s/mm2 were used, three orthogonal motion proving gradients (MPGs) were applied, and synthesized images were generated. The regions of interest (ROIs) were ssigned at the lesions on the 1st DWI and pasted onto the 2nd at the same size and location. Voxel-wise ADC was calculated by fitting the signal intensity change of each voxel into a mono-exponential curve. ADCs calculated from 1st and 2nd DWI were defined as ADC-1st and ADC-2nd, respectively. To investigate the repeatability of voxel-wise ADC in each lesion, ADC-1st and ADC-2nd were compared using Wilcoxon matched-pairs signed rank test and linear regression. To onsider repeatability of ADC histogram metrics for all lesions, minimal, 25%, median, 75%, maximum, mean, skewness, and kurtosis of ADC-1st and ADC-2nd for each lesion were compared using linear regression and Bland-Altman plot.Results: For repeatability of voxel-wise ADC, significant differences were observed between ADC-1st and ADC-2nd in 5 lesions. Linear regression did not show significance of the slope in 5 lesions. As for repeatability of ADC histogram metrics, all ADC histogram metrics except skewness and kurtosis showed significance of the slope in linear regression (p<0.0001) and high repeatability in Bland-Altman plot.Conclusion: The histogram metrics of voxel-wise ADC like minimum, 25%, median, 75%, maximum, and mean show high repeatability, but skewness and kurtosis did not

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016)

Background and purposeThe Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in February 2017 and published in the Journal of JSICM, [2017; Volume 24 (supplement 2)] https://doi.org/10.3918/jsicm.24S0001 and Journal of Japanese Association for Acute Medicine [2017; Volume 28, (supplement 1)] http://onlinelibrary.wiley.com/doi/10.1002/jja2.2017.28.issue-S1/issuetoc.This abridged English edition of the J-SSCG 2016 was produced with permission from the Japanese Association of Acute Medicine and the Japanese Society for Intensive Care Medicine.MethodsMembers of the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine were selected and organized into 19 committee members and 52 working group members. The guidelines were prepared in accordance with the Medical Information Network Distribution Service (Minds) creation procedures. The Academic Guidelines Promotion Team was organized to oversee and provide academic support to the respective activities allocated to each Guideline Creation Team. To improve quality assurance and workflow transparency, a mutual peer review system was established, and discussions within each team were open to the public. Public comments were collected once after the initial formulation of a clinical question (CQ) and twice during the review of the final draft. Recommendations were determined to have been adopted after obtaining support from a two-thirds (> 66.6%) majority vote of each of the 19 committee members.ResultsA total of 87 CQs were selected among 19 clinical areas, including pediatric topics and several other important areas not covered in the first edition of the Japanese guidelines (J-SSCG 2012). The approval rate obtained through committee voting, in addition to ratings of the strengths of the recommendation, and its supporting evidence were also added to each recommendation statement. We conducted meta-analyses for 29 CQs. Thirty-seven CQs contained recommendations in the form of an expert consensus due to insufficient evidence. No recommendations were provided for five CQs.ConclusionsBased on the evidence gathered, we were able to formulate Japanese-specific clinical practice guidelines that are tailored to the Japanese context in a highly transparent manner. These guidelines can easily be used not only by specialists, but also by non-specialists, general clinicians, nurses, pharmacists, clinical engineers, and other healthcare professionals

Origin of methane-rich natural gas at the West Pacific convergent plate boundary

Methane emission from the geosphere is generally characterized by a radiocarbon-free signature and might preserve information on the deep carbon cycle on Earth. Here we report a clear relationship between the origin of methane-rich natural gases and the geodynamic setting of the West Pacific convergent plate boundary. Natural gases in the frontal arc basin (South Kanto gas fields, Northeast Japan) show a typical microbial signature with light carbon isotopes, high CH4/C2H6 and CH4/3He ratios. In the Akita-Niigata region – which corresponds to the slope stretching from the volcanic-arc to the back-arc –a thermogenic signature characterize the gases, with prevalence of heavy carbon isotopes, low CH4/C2H6 and CH4/3He ratios. Natural gases from mud volcanoes in South Taiwan at the collision zone show heavy carbon isotopes, middle CH4/C2H6 ratios and low CH4/3He ratios. On the other hand, those from the Tokara Islands situated on the volcanic front of Southwest Japan show the heaviest carbon isotopes, middle CH4/C2H6 ratios and the lowest CH4/3He ratios. The observed geochemical signatures of natural gases are clearly explained by a mixing of microbial, thermogenic and abiotic methane. An increasing contribution of abiotic methane towards more tectonically active regions of the plate boundary is suggested.論文http://purl.org/coar/resource_type/c_650

Repeatability analysis of ADC histogram metrics of the uterus

Background Recently, histogram analysis based on voxel-wise apparent diffusion coefficient (ADC) value distribution has been increasingly performed. However, few studies have been reported regarding its repeatability. Purpose To evaluate the repeatability of ADC histogram metrics of the uterus in clinical magnetic resonance imaging (MRI). Material and Methods Thirty-three female patients who underwent pelvic MRI including diffusion-weighted imaging (DWI) were prospectively included after providing informed consent. Two sequential DWI acquisitions with identical parameters and position were obtained. Regions of interest (ROIs) for histologically confirmed uterine lesions (five cervical and three endometrial cancers, and one endometrial hyperplasia) and normal appearing tissues (21 endometrium and 33 myometrium) were assigned on the first DWI dataset and then pasted onto the second DWI dataset. ADC histogram metrics within the ROIs were calculated and repeatability was evaluated by calculating within-subject coefficient of variance (%) (wCV (%)) and Bland-Altman plot (%). Results ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy showed high repeatability (wCV (%) <7, 95% limit of agreement in Bland-Altman plot (%) <+/- 20), followed by ADC minimum (wCV (%) = 8.12, 95% limit of agreement in Bland-Altman plot (%) <+/- 30). However, ADC skewness and kurtosis showed very low repeatability in all evaluations. Conclusion ADC histogram metrics like ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy are robust biomarkers and could be applicable to clinical use. However, ADC skewness and kurtosis lack robustness. Radiologists should keep these characteristics and limitations in mind when interpreting quantitative DWI