Background & aims: Body composition analysis on CT images is a valuable tool for sarcopenia assessment. We aimed to develop and validate a deep neural network applicable to whole-body CT images of PET-CT scan for the automatic volumetric segmentation of body composition. Methods: For model development, one hundred whole-body or torso 18 F-fluorodeoxyglucose PETeCT scans of 100 patients were retrospectively included. Two radiologists semi-automatically labeled the following seven body components in every CT image slice, providing a total of 46,967 image slices from the 100 scans for training the 3D U-Net (training, 39,268 slices; tuning, 3116 slices; internal validation, 4583 slices): skin, bone, muscle, abdominal visceral fat, subcutaneous fat, internal organs with vessels, and central nervous system. The segmentation accuracy was assessed using reference masks from three external datasets: two Korean centers (4668 and 4796 image slices from 20 CT scans, each) and a French public dataset (3763 image slices from 24 CT scans). The 3D U-Net-driven values were clinically validated using bioelectrical impedance analysis (BIA) and by assessing the model's diagnostic performance for sarcopenia in a community-based elderly cohort (n ¼ 522). Results: The 3D U-Net achieved accurate body composition segmentation with an average dice similarity coefficient of 96.5%e98.9% for all masks and 92.3%e99.3% for muscle, abdominal visceral fat, and subcutaneous fat in the validation datasets. The 3D U-Net-derived torso volume of skeletal muscle and fat tissue and the average area of those tissues in the waist were correlated with BIA-derived appendicular lean mass (correlation coefficients: 0.71 and 0.72, each) and fat mass (correlation coefficients: 0.95 and 0.93, each). The 3D U-Net-derived average areas of skeletal muscle and fat tissue in the waist were independently associated with sarcopenia (P < .001, each) with adjustment for age and sex, providing an area under the curve of 0.858 (95% CI, 0.815 to 0.901).
Sequencing the mitochondrial control region is very useful for individual identification when conventional DNA typing using autosomal STRs is unavailable. However, low discriminatory power is a problem and another polymorphic locus within the mitochondrial genome is necessary. The cytochrome B (MTCYB) gene, which has undergone several changes during evolution, may be a good candidate for this purpose. Here the sequencing data of the MTCYB gene of 98 unrelated Koreans is presented. A total of 30 polymorphic sites were found which were distributed evenly along the gene. All were nucleotide substitutions and no insertions/deletions were noted. A total of 22 different MTCYB lineages were revealed. Out of 22 different control region lineages with 79 samples which shared the same D-loop sequence with some others within a lineage, 10 lineages with 37 samples could be sub-grouped according to different MTCYB sequences. Some issues concerning the MTCYB gene polymorphism are discussed.
Abstract:Background:Clinical reasoning ability is an important factor in a physician's competence and thus should be taught and tested in medical schools. Medical schools generally use objective structured clinical examinations (OSCE) to measure the clinical competency of medical students. However, it is unknown whether OSCE can also evaluate clinical reasoning ability. In this study, the authors investigated whether OSCE scores reflected students' clinical reasoning abilities.Methods:Sixty-five fourth-year medical students participated in this study. Medical students completed the OSCE with 4 cases using standardized patients. For assessment of clinical reasoning, students were asked to list differential diagnoses and the findings that were compatible or not compatible with each diagnosis. The OSCE score (score of patient encounter), diagnostic accuracy score, clinical reasoning score, clinical knowledge score and grade point average (GPA) were obtained for each student, and correlation analysis was performed.Results:Clinical reasoning score was significantly correlated with diagnostic accuracy and GPA (correlation coefficient = 0.258 and 0.380; P = 0.038 and 0.002, respectively) but not with OSCE score or clinical knowledge score (correlation coefficient = 0.137 and 0.242; P = 0.276 and 0.052, respectively). Total OSCE score was not significantly correlated with clinical knowledge test score, clinical reasoning score, diagnostic accuracy score or GPA.Conclusions:OSCE score from patient encounters did not reflect the clinical reasoning abilities of the medical students in this study. The evaluation of medical students' clinical reasoning abilities through OSCE should be strengthened.
Sudden unexpected deaths due to cardiovascular diseases make up almost half of all natural deaths. Practical guidelines are needed for forensic autopsy practice in cases of natural unexpected deaths due to ischemic heart disease or other cardiovascular diseases in Korea. An evaluation of the clinical history is the first step, including the collection of all available information on the subject. As a standard autopsy procedure, every subsystem of the heart and vessels should be thoroughly studied including the coronary arteries, the myocardium, the cardiac valves, and the conducting system. In addition, histological, toxicological, biochemical and molecular analysis need to be applied to the detection of myocardial infarction from the medico‐legal point of view. Also important is the assessment of risk factors for natural unexpected cardiac death (NUCD) in order to establish a cause–effect relationship. There are three groups of ischemic conditions of heart leading to NUCD, those being acute myocardial infarction, atherosclerotic heart disease and critical coronary atherosclerosis. Additionally, there are practical concerns on formulating the report. Pathologists may use sudden cardiac death or NUCD as a main diagnosis when there is no alternative diagnosis, though they would do better to comment on conditions contributing to the death. Finally, pathologists should be encouraged to suspect unexplained causes of death in order to find clearer answers.
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