In recent years, new technologies have become available for imaging small animals. The use of animal models in basic and preclinical sciences, for example, offers the possibility of testing diagnostic markers and drugs, which is becoming crucial in the success and timeliness of research and is allowing a more efficient approach in defining study objectives and providing many advantages for both clinical research and the pharmaceutical industry. The use of these instruments offers data that are more predictive of the distribution and efficacy of a compound. The mouse, in particular, has become a key animal model system for studying human disease. It offers the possibility of manipulating its genome and producing accurate models for many human disorders, thus resulting in significant progress in understanding pathologenic mechanisms. In neurobiology, the possibility of simulating neurodegenerative diseases has enabled the development and validation of new treatment strategies based on gene therapy or cell grafting. Noninvasive imaging in small living animal models has gained increasing importance in preclinical research, itself becoming an independent specialty. The aim of this article is to review the characteristics of these systems and illustrate their main applications.
Abstract-Synchrotron-based digital radiography and microtomography devices are powerful, nondestructive, high-resolution research tools. In this paper, we present a linear system with a pixel size of 22.5 m and a field-of-view (FOV) 13 cm long and about 1 mm high. The system is composed of a linear converter GOS screen coupled to an intensified electron-bombarded CCD (EBCCD) camera, by means of a rectangular-to-linear fiber optic adapter. This optical guide is composed of seven bundles, each one transporting light in a coherent way to preserve spatial information. In this way, a high spatial resolution over an extended FOV is obtained. The detector works as an X-ray scanner by means of a high-precision translation mechanical device with 18 cm travel range. The total FOV obtained this way is 13 cm long and 18 cm high. The aim of this paper is to demonstrate the feasibility of this system to investigate a large area of a bone and to calculate the appropriate histomorphometric parameters. Here we present an investigation gained at ELETTRA synchrotron facility at Trieste, Italy. A monochromatic 34-keV beam has been used for imaging a human proximal femur, about 9 cm in width, with our system. The reconstructed images (13 cm 13 cm) were cross sections containing femoral head, femoral neck, and greater trochanter. The local variations in trabecular and cortical structure of the examined bone were clearly visible at a level not obtainable with medical CT scanners. The used spatial resolution allowed the visualization of thin trabeculae, which typically lie in a range of 100 m or lower. The quality of the reconstructed cross-section images confirmed that the system presented is a novel tool for high resolution three-dimensional (3-D) imaging of bone structure, with a pixel size over a volume of interest not achievable with conventional microCT scanners.
Body composition assessment (BCA) represents a valid instrument to evaluate nutritional status through the quantification of lean and fat tissue, in healthy subjects and sick patients. According to the clinical indication, body composition (BC) can be assessed by different modalities. To better analyze radiation risks for patients involved, BCA procedures can be divided into two main groups: the first based on the use of ionizing radiation (IR), involving dual energy X-ray absorptiometry (DXA) and computed tomography (CT), and others based on non-ionizing radiation (NIR) [magnetic resonance imaging (MRI)].Ultrasound (US) techniques using mechanical waves represent a separate group. The purpose of our study was to analyze publications about IR and NIR effects in order to make physicians aware about the risks for patients undergoing medical procedures to assess BCA providing to guide them towards choosing the most suitable method. To this end we reported the biological effects of IR and NIR and their associated risks, with a special regard to the excess risk of death from radio-induced cancer. Furthermore, we reported and compared doses obtained from different IR techniques, giving practical indications on the optimization process. We also summarized current recommendations and limits for techniques employing NIR and US.The authors conclude that IR imaging procedures carry relatively small individual risks that are usually justified by the medical need of patients, especially when the optimization principle is applied. As regards NIR imaging procedures, a few studies have been conducted on interactions between electromagnetic fields involved in MR exam and biological tissue. To date, no clear link exists between MRI or associated magnetic and pulsed radio frequency (RF) fields and subsequent health risks, whereas acute effects such as tissue burns and phosphenes are well-known; as regards the DNA damage and the capability of NIR to break chemical bonds, they are not yet robustly demonstrated. MRI is thus considered to be very safe for BCA as well US procedures.
Sarcopenia and osteoporosis are recognized as two major health problems worldwide, responsible for a serious clinical and financial burden due to the increasing life expectancy. Although it can also develop in young adults, loss of bone and muscle affects predominantly elderly patients leading to a huge increase in physical disability, hospitalizations and mortality. According to the World Health Organization (WHO), osteoporosis is a "systemic skeletal disease, characterized by low mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk" 1. The age-standardized prevalence of osteoporosis in the European population is 12% for women and 12.2% for men aged 50-79 years, with an overall age-standardized incidence of 10.7 per 1000 person-years in women and 5.7 per 1000 person-years in men 2 and it is expected to increase to more than 14 million worldwide by 2020 3. Sarcopenia is a "syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death" 4. Sarcopenia is a condition still partly unknown and under-diagnosed in the clinical practice. Even if a univocally accepted definition of sarcopenia has not yet been defined, its prevalence is estimated around 13% in individuals between 60 and 70 years, despite it can reach reaches almost 50% of people over 80 years of age 5. Bone and muscle are two closely interacting tissues for several reasons. The most intuitive reason is their complementarity in allowing the function of locomotion:
IntraOperative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionising radiation to the cancer tissue, after tumour ablation, during surgery. The Novac7 is a new linear accelerator expressly conceived for IORT that supplies electron beams at several energy, with high dose rate. These peculiar characteristics give rise to some complications with classical dosimetric techniques. In the framework of a research contract between ENEA and the Physics Department of Bologna, Italy, an original digital system has been developed to study and visualise the Novac7 electron beam in real time.The system is conceived as a grid consisting of two bundles of scintillating optical fibres (SOF) over-crossing each other, optically coupled with two arrays of photodiodes as read-out system.The problem of image reconstruction can be expressed as follows: there are only two profiles, or data arrays, which correspond respectively to the light emitted along the fibres perpendicular to the X-axis for the X-profile, and along the fibres perpendicular to the Y-axis for the Y-profile. This problem is not dissimilar to the reconstruction problem in tomography where several projections should be composed to trace them back to the original image. Unfortunately, here we have only two profiles: we have two one-dimensional profiles and are seeking one bidimensional image that could produce them.We selected a known beam image acquired by another digital instrument, then we extracted from it the two profiles simulating the acquisition arrays. Subsequently, we tested several reconstruction algorithms on these profiles, comparing the reconstructed image with the original one. We started from the simple sum algorithm until to iterative algorithms, searching the best compromise between the computational complexity and an high precision.We found that the iterative method is the best solution: it respects the geometrical characteristics and the absolute intensity values of the original image. Moreover it can reconstruct the image in a time of less than one second, a very good result.
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