RESUMO
This study proposes a multiclass model to classify the severity of knee osteoarthritis (KOA) using bioimpedance measurements. The experimental setup considered three types of measurements using eight electrodes: global impedance with adjacent pattern, global impedance with opposite pattern, and direct impedance measurement, which were taken using an electronic device proposed by authors and based on the Analog Devices AD5933 impedance converter. The study comprised 37 participants, 25 with healthy knees and 13 with three different degrees of KOA. All participants performed 20 repetitions of each of the following five tasks: (i) sitting with the knee bent, (ii) sitting with the knee extended, (iii) sitting and performing successive extensions and flexions of the knee, (iv) standing, and (v) walking. Data from the 15 experimental setups (3 types of measurements×5 exercises) were used to train a multiclass random forest. The training and validation cycle was repeated 100 times using random undersampling. At each of the 100 cycles, 80% of the data were used for training and the rest for testing. The results showed that the proposed approach achieved average sensitivities and specificities of 100% for the four KOA severity grades in the extension, cyclic, and gait tasks. This suggests that the proposed method can serve as a screening tool to determine which individuals should undergo x-rays or magnetic resonance imaging for further evaluation of KOA.
Assuntos
Impedância Elétrica , Aprendizado de Máquina , Osteoartrite do Joelho , Humanos , Osteoartrite do Joelho/fisiopatologia , Osteoartrite do Joelho/diagnóstico por imagem , Feminino , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Idoso , Marcha , Adulto , Articulação do Joelho/fisiopatologia , Articulação do Joelho/diagnóstico por imagem , Sensibilidade e Especificidade , Caminhada , Reprodutibilidade dos TestesRESUMO
This study proposes a low-cost, portable, eight-channel electrical impedance tomograph based on the AD5933 impedance converter. The patterns for current injection and voltage measurement are managed by an Arduino Mega 2560 board and four 74HC4067 Texas Instruments multiplexers. Regarding the experimental results, the errors in the impedance estimates of an electrical circuit that represents a Cole model were less than 1.14% for the magnitude and 4.15% for the phase. Furthermore, the signal-to-noise ratio measured in a resistive phantom was 55.23 dB. Additional experiments consisted of placing five spheres of different size and conductivity in a saline tank, measuring their impedance through eight electrodes, and then generating impedance maps using the Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS). These maps were different for each sphere, suggesting the proposed prototype as a promising alternative for medical applications.
RESUMO
Fournier's gangrene is a rare but life-threatening disease characterized by necrotizing fasciitis of the perineal area. It mostly affects adult patients with an immunosuppressant factor and there are only a few cases reported in children. Use of nonsteroidal anti-inflammatory drugs has been associated with necrotizing fasciitis probably because of suppressing host immunity during infection. We describe a case of a six month old infant without immunosuppressant factors, with Founier's gangrene probably associated with nonsteroidal anti-inflammatory intake.