Thermal Evaluation of Multi-Antenna Systems Proposed to Treat Bone Tumors: Finite Element Analysis.

Microwave ablation is commonly used in soft tissue tumors, but its application in bone tumors has been barely analyzed. Antennas to treat bone tissue (~3 cm2), has been lately designed. Bone tumors at pathological stage T1 can reach 8 cm wide. An antenna cannot cover it; therefore, our goal is to evaluate the thermal performance of multi-antenna arrays. Linear, triangular, and square configurations of double slot (DS) and monopole (MTM) antennas were evaluated. A parametric study (finite element method), with variations in distance between antennas (ad) and bone thickness (bt) was implemented. Array feasibility was evaluated by SWR, ablated tissue volume, etc. The linear configuration with DS and MTM antennas showed SWR ≤ 1.6 for ad = 1 mm−15 mm and bt = 20 mm−40 mm, and ad = 10 mm−15 mm and bt = 25 mm−40 mm, respectively; the triangular showed SWR ≤ 1.5 for ad = 5 mm−15 mm and bt = 20 mm−40 mm and ad = 10 mm−15 mm and bt = 25 mm−40 mm. The square configuration (DS) generated SWR ≤ 1.5 for ad = 5 mm−20 mm and bt = 20 mm−40 mm, and the MTM, SWR ≤ 1.5 with ad = 10 mm and bt = 25 mm−40 mm. Ablated tissue was 4.65 cm3−10.46 cm3 after 5 min. According to treatment time and array configuration, maximum temperature and ablated tissue is modified. Bone tumors >3 cm3 can be treated by these antenna-arrays.

Computed tomography is a feasible method for quantifying bone density in Macaca mulatta.

Osteopathologies are a result of advanced age and decreased bone density and represent a global health problem. It is therefore important to generate models for longitudinal studies of the pathophysiology in order to improve early diagnosis and develop preventive therapies. For this kind of research, the use of computed tomography (CT) to evaluate bone health offers advantages over other techniques since it provides more complete information. The aim of this prospective, pilot study was to obtain measurements of the left femur from a population in captivity of 32 rhesus monkeys (Macaca mulatta) in order to standardize the model for future research. Healthy subjects from 5 to 28 years old were chosen. Three groups with different ages were formed as follows: (1) 5-9 years, (2) 10-19 years, and (3) 20-28 years. Semi-automatic segmentation by threshold defined the regions of interest, which were subdivided in the range of 300-700 Hounsfield units (HU) for trabecular bone and >700 HU for cortical bone. Then, the proportional ratios of the volumes of trabecular bone and cortical bone were obtained. Significant differences (analysis of variance test) in the averages of Hounsfield units, cortical, and trabecular bone proportions from each age group proved that a decrease in bone density begins at approximately 20 years of age. The values presented here, as well as the method to obtain them from CT scans, can be used as a baseline in a primate model for long-term research in bone pathology diagnosis and treatment.

Analysis of the Unsuccessful Efforts to Design & Construct Invasive Mechanical COVID-19 Ventilators in Mexico: Did the Current BME Curricula at Mexican Universities Contribute to the Failure?

Mexico was caught unprepared to deal with the current COVID-19 pandemic. One of the most egregious failures was the incapability to provide an additional 10,000 ventilators in order to cope with the excess demand. The Mexican government proposed a program for funding the development of these devices and over 100 designs were submitted but were of below standard quality and performance. Only three designs have been approved up to date.This work analyzes the failures from the point of view of the incapability to design, develop and test locally made ventilator designs, and asks whether the national university system, after a history of 48 years of producing thousands of Biomedical Engineering students in over 60 institutions has become incapable of delivering a design of a medical device of medium complexity.

Updating the Biomedical Engineering Curriculum in Latin America: Moving from management and maintenance to Design and Development of Medical Devices.

Biomedical Engineering as an undergraduate degree in Latin America is not new. However, most programs have the objective to produce professionals dedicated to the management and maintenance of health care technology. We believe that there is an important area of opportunity in the education of engineers who are competent in the design and development of medical devices. Among the 100 programs in the region there could be a few which could stand out as providers of such professionals. This work proposes a curricular structure to fulfill these aims.

Critical assessment and outlook for the 50 biomedical engineering undergraduate programs in Mexico.

Biomedical Engineering (BME) has been taught in Mexico at the undergraduate level for over forty years. The rationale for the introduction of this profession was to help manage and maintain the growing technological infrastructure in the health care system during the seventies. Owing to this, it is not surprising that early versions of the BME curricula were oriented towards clinical engineering and medical instrumentation. In the last decade the number of programs has grown from three in the seventies and eighties to fifty at present. This work is the result of the analysis of the BME programs in all the institutions that offer this degree in Mexico. Three main issues were studied: the curricula, the sub-disciplines that were emphasized in the programs and the job market. Results have shown a striking resemblance in most of the programs, which are mostly dedicated to teaching aspects of medical instrumentation and clinical engineering. These results reflect an agreement with the requirements of the job market, but since most job offerings are for low-paying positions in sales, service and hospital maintenance, we question the wisdom of stressing these sub-specialties at research universities, where faculties and research labs offer a wide variety of options. An analysis of work at these centers shows that most of the results are publications, so the need to emphasize translational research and partnerships with industry are suggested.

Analysis of the impact of medical technology assessment subjects on BME curricula.

This paper presents and analyzes the factors that have arisen on the implementation of the medical technology assessment and management courses, and the academic methodologies used to deal with them. Five courses that cover topics as Technology Management, Health Economics, Quality Assessment, Innovation and Entrepreneurship were designed as electives for BME curriculum and have been taught for the last two years. The activities carried out within the courses are described and their impact on the comprehension of the course contents are presented. Also, several elements and factors pertaining to the teaching-learning process are discussed. Future perspectives for the students that follow this sub-specialty branch of the BME curriculum are presented.

Automatic error detection in the clinical measurement of gastric impedance spectra.

Gastric impedance spectroscopy has been proposed as a method of monitoring mucosal injury due to hypoperfusion and ischemia in the critically ill. During validation tests for this procedure, it was found that 60% of the measurements had errors by factors inherent to the clinical setting, indicating that some kind of automatic error detection should be incorporated to potentially avoid the loss of measurements. This paper presents an algorithm developed to detect errors due to bad connection, bad location or bad contact of the electrode probe. A labeled database with 20,908 sets of 92 spectral measurements each, obtained from critically ill patients was used as training/testing data. To reduce the dimensionality, the database was resized by dividing the spectral range into four bands, and then by computing mean and standard deviation in magnitude, phase, resistance and reactance for each band and measurement. Initial exploration into the data space was performed by k-means clustering, establishing the number of classes. Sequential Forward Selection was performed to determine best features from the reduced data set. Finally, Support Vector Machine classifiers were designed in a one-vs-rest hierarchical scheme to classify the quality of the spectra. Each classifier gave a hit rate greater than 95% and an area under the relative operating characteristic curve of 0.99. In a validation run with cardiac surgery and intensive care unit patient spectra, the error rates were 2.3% and 8.4% respectively.