Sensorless parameter estimation of electromagnetic transducer considering eddy currents

This paper presents a method of estimating the parameters of an electromagnetic transducer without sensors. The proposed method utilizes the measured admittance of the electromagnetic transducer, and therefore position, velocity, and/or acceleration sensors are not necessary in this framework. Novel impedance models are proposed based on the basic physical principles of electromagnetics; in particular, the effect of eddy currents has been included in these proposed models. The validity of the proposed estimation method and models was experimentally demonstrated by comparing the parameter estimation and vibration control capabilities of the proposed models with three conventional models. © 2017 Elsevier LtdEmbargo period 12 month

Resection of positive tissue on methionine‐PET is associated with improved survival in glioblastomas

Abstract Background and purpose The volume of excised tumor in contrast‐enhanced areas evaluated via magnetic resonance imaging is known to have a strong influence on the survival of patients with glioblastoma (GBM). In this study, we investigated the effect of tumor resection on the survival of patients with GBM in the 11C‐methionine (MET) accumulation area using MET‐positron emission tomography (MET‐PET). Methods A total of 26 patients (median age, 69 years; 15 males) who had undergone tumor resection and MET‐PET before and after surgery, after being newly diagnosed with GBM, were included in the study. MET‐PET before and after tumor resection were compared. The association between the decrease in the maximum standardized uptake value (SUV) of the tumor divided by the normal cortical mean SUV (%; ΔT/N), the MET extent of resection (MET‐EOR) from the % reduction in the MET accumulation area (%), and residual MET accumulation area (in cm3; MET‐residual tumor volume [RTV]), as well as the survival time of patients with GBM, were evaluated via univariate analysis. Results ΔT/N were positively associated with survival (hazard ratio [HR], 0.98 [95% confidence interval (CI), 0.97–0.99], p = .02). MET‐RTV revealed a negative association with survival (HR, 1.02 [95% CI, 1.01–1.04], p = .04). Additionally, MET‐EOR showed a strong trend with survival (HR, 0.99 [95% CI, 0.97–1.01], p = .06). Conclusions Surgical resection of MET‐accumulated areas in GBM significantly prolongs the survival of patients with GBM. However, a prospective large‐scale multicenter study is needed to confirm our findings

Predicting Isocitrate Dehydrogenase Status in Non-Contrast-Enhanced Adult-Type Astrocytic Tumors Using Diffusion Tensor Imaging and ¹¹C-Methionine, ¹¹C-Choline, and ¹⁸F-Fluorodeoxyglucose PET

We aimed to differentiate the isocitrate dehydrogenase (IDH) status among non-enhanced astrocytic tumors using preoperative MRI and PET. We analyzed 82 patients with non-contrast-enhanced, diffuse, supratentorial astrocytic tumors (IDH mutant [IDH-mut], 55 patients; IDH-wildtype [IDH-wt], 27 patients) who underwent MRI and PET between May 2012 and December 2022. We calculated the fractional anisotropy (FA) and mean diffusivity (MD) values using diffusion tensor imaging. We evaluated the tumor/normal brain uptake (T/N) ratios using 11C-methionine, 11C-choline, and 18F-fluorodeoxyglucose PET; extracted the parameters with significant differences in distinguishing the IDH status; and verified their diagnostic accuracy. Patients with astrocytomas were significantly younger than those with glioblastomas. The following MRI findings were significant predictors of IDH-wt instead of IDH-mut: thalamus invasion, contralateral cerebral hemisphere invasion, location adjacent to the ventricular walls, higher FA value, and lower MD value. The T/N ratio for all tracers was significantly higher for IDH-wt than for IDH-mut. In a composite diagnosis based on nine parameters, including age, 84.4% of cases with 0–4 points were of IDH-mut; conversely, 100% of cases with 6–9 points were of IDH-wt. Composite diagnosis using all parameters, including MRI and PET findings with significant differences, may help guide treatment decisions for early-stage gliomas

Differentiation of astrocytoma between grades II and III using a combination of methionine positron emission tomography and magnetic resonance spectroscopy

Objective: This study aimed to establish a method for differentiating between grades II and III astrocytomas using preoperative imaging. Methods: We retrospectively analyzed astrocytic tumors, including 18 grade II astrocytomas (isocitrate dehydrogenase (IDH)-mutant: IDH-wildtype = 8:10) and 56 grade III anaplastic astrocytomas (37:19). We recorded the maximum methionine (MET) uptake ratios (tumor-to-normal: T/N) on positron emission tomography (PET) and three MRS peak ratios: choline (Cho)/creatine (Cr), N-acetyl aspartate (NAA)/Cr, and Cho/NAA, between June 2015 and June 2020. We then evaluated the cut-off values to differentiate between grades II and III. We compared the grading results between contrast enhancement effects on MR and combinational diagnostic methods (CDM) on a scatter chart using the cutoff values of the T/N ratio and MRS parameters. Results: The IDH-mutant group showed significant differences in the Cho/NAA ratio between grades II and III using univariate analysis; however, multiple regression analysis results negated this. The IDH-wildtype group showed no significant differences between the groups. Contrast enhancement effects also showed no significant differences in IDH status. Accordingly, regardless of the IDH status, no statistically independent factors differentiated between grades II and III. However, CDMs showed higher sensitivity and negative predictive value in distinguishing them than MRI contrast examinations for both IDH statuses. We demonstrated a significantly higher diagnostic rate of grade III than of grade II with CDM, which was more striking in the IDH-mutant group than in the wild-type group. Conclusions: CDM could be valuable in differentiating between grade II and III astrocytic tumors

Population-neuroscience study of the Tokyo TEEN Cohort (pn-TTC):Cohort longitudinal study to explore the neurobiological substrates of adolescent psychological and behavioral development.

Adolescence is a crucial stage of psychological development and is critically vulnerable to the onset of psychopathology. However, our understanding of how maturation of endocrine, epigenetics, and brain circuit may underlie the psychological development in adolescence has not been integrated. Here, we introduce our research project, the "population-neuroscience study of the Tokyo TEEN Cohort (pn-TTC)," a longitudinal study to explore the neurobiological substrates of development during adolescence