Metabolite-Specific Echo-Planar Imaging of Hyperpolarized [1-13C]Pyruvate at 4.7 T

Although hyperpolarization (HP) greatly increases the sensitivity of 13C MR, the usefulness of HP in vivo is limited by the short lifetime of HP agents. To address this limitation, we developed an echo-planar (EPI) sequence with spectral-spatial radiofrequency (SSRF) pulses for fast and efficient metabolite-specific imaging of HP [1-13C]pyruvate and [1-13C]lactate at 4.7 T. The spatial and spectral selectivity of each SSRF pulse was verified using simulations and phantom testing. EPI and CSI imaging of the rat abdomen were compared in the same rat after injecting HP [1-13C]pyruvate. A procedure was also developed to automatically set the SSRF excitation pulse frequencies based on real-time scanner feedback. The most significant results of this study are the demonstration that a greater spatial and temporal resolution is attainable by metabolite-specific EPI as compared with CSI, and the enhanced lifetime of the HP signal in EPI, which is attributable to the independent flip angle control between metabolites. Real-time center frequency adjustment was also highly effective for minimizing off-resonance effects. To the best of our knowledge, this is the first demonstration of metabolite-specific HP 13C EPI at 4.7 T. In conclusion, metabolite-specific EPI using SSRF pulses is an effective way to image HP [1-13C]pyruvate and [1-13C]lactate at 4.7 T.

Avaliação da função sexual e miccional de homens transexuais

A transexualidade trata da mudança dos indivíduos de seu sexo masculino ou feminino identificado no nascimento para viver em sociedade sob sua alternativa de identidade de gênero. Visando essa adequação são realizados procedimentos transexualizadores, no entanto, pouco se conhece sobre a função sexual e urinária após esses processos. Neste sentido, este estudo propôs avaliar as funções sexuais e miccionais de homens transexuais submetidos à terapia hormonal. Participaram do estudo 13 homens transexuais e foram utilizados os questionários: Escala de Desconforto Sexual Feminino (FSDS-R), Índice de função sexual feminina (FSFI), Teste de Três Perguntas sobre Incontinência (3IQ), Protection, Amount, Frequency, Adjustment, Bodyimage (PRAFAB). Foi utilizado o software Excel para entrada dos dados, confecção das tabelas e análise estatística descritiva. No FSDS-R, 10 (76,92%) dos homens trans apresentam-se desconfortáveis sexualmente. A pontuação média da FSFI foi de 14,8 pontos, sugerindo disfunção sexual. No teste de 3IQ, 25% relataram perder urinária, destes, 75% apresentam urgência miccional e 25% apresentam Incontinência Urinária (IU) por esforço. No score total do PRAFAB, 50% apresentaram IU leve e 50% obtiveram IU moderada. Portanto, a avaliação foi positiva para tendência a disfunções sexuais nesta população. No que concerne a função miccional, a minoria dos homens trans manifestaram alterações.

Resonant LCL Converter with Frequency-Pulse-Width Control

The paper considers the features of frequency-pulse-width control in a resonant LCL converter with an active rectifier in the mode of parametric stabilization of the output current. The analysis of the properties of the LCL converter during regulation by the rectifier is carried out, the phase frequency characteristic and the coefficient of parametric stabilization are obtained. It is shown that the rectifier introduces a reactive component into the impedance of the resonant circuit. It is illustrated that the introduction of the control angle leads to the loss of roots by the equation on a part of the load range. The estimation of the frequency adjustment in the converter is carried out, the control characteristic is obtained, the energy advantages of frequency-pulse-width control are demonstrated, which consists in the zero phase of the inverter current and minimization of the recuperation interval