Radiography, computed tomography and magnetic resonance imaging at 0.5 Tesla of mechanically inducedosteoarthritis in rabbit knees

In the present experimental study we assessed induced osteoarthritis data in rabbits, compared three diagnostic methods, i.e., radiography (XR), computed tomography (CT) and magnetic resonance imaging (MRI), and correlated the imaging findings with those obtained by macroscopic evaluation. Ten young female rabbits of the Norfolk breed were used. Seven rabbits had the right knee immobilized in extension for a period of 12 weeks (immobilized group), and three others did not have a limb immobilized and were maintained under the same conditions (control group). Alterations observed by XR, CT and MRI after the period of immobilization were osteophytes, osteochondral lesions, increase and decrease of joint space, all of them present both in the immobilized and non-immobilized contralateral limbs. However, a significantly higher score was obtained for the immobilized limbs (XT: P = 0.016, CT: P = 0.031, MRI: P = 0.0156). All imaging methods were able to detect osteoarthritis changes after the 12 weeks of immobilization. Macroscopic evaluation identified increased thickening of joint capsule, proliferative and connective tissue in the femoropatellar joint, and irregularities of articular cartilage, especially in immobilized knees. The differences among XR, CT and MRI were not statistically significant for the immobilized knees. However, MRI using a 0.5 Tesla scanner was statistically different from CT and XR for the non-immobilized contralateral knees. We conclude that the three methods detected osteoarthritis lesions in rabbit knees, but MRI was less sensitive than XR and CT in detecting lesions compatible with initial osteoarthritis. Since none of the techniques revealed all the lesions, it is important to use all methods to establish an accurate diagnosis.

Local edema and hemorrhage caused by Crotalus durissus terrificus envenoming evaluated by magnetic resonance imaging (MRI)

The objective of this study was to detect the presence of local edema and hemorrhage caused by Crotalus durissus terrificus envenoming using magnetic resonance imaging (MRI). Six patients bitten by Crotalus durissus terrificus snakes were treated at the Emergency Unit and Tropical Diseases Unit of Botucatu School of Medicine, UNESP, Säo Paulo State, Brazil. After receiving specific serotherapy, the patients were submitted to MR of the bite site. Post contrast T1 and T2 spin-echo MRI were obtained revealing the following lesions: edema associated with hemorrhage in subcutaneous and muscular tissue (n=3), edema in subcutaneous tissue (n=2), and perimuscular hemorrhage (n=1). In this study, MR demonstrated a local effect of Crotalus durissus terrificus envenoming in inducing edema and hemorrhage, mainly in muscular tissues and perimuscular areas. These results indicate that Crotalus durissus terrificus venom cause a local muscular tissue damage in human envenoming represented by edema and hemorrhage.

Tissue damage caused by Bothrops sp envenoming evaluated by magnetic resonance imaging (MRI)

The objective of this clinical study was to evaluate local tissue damage caused by Bothrops sp envenoming in relation to lesion type and damaged tissues using magnetic resonance imaging (MRI). Fifteen patients bitten by Bothrops snakes were treated at the Emergency Unit of the Tropical Diseases Unit at the University Hospital, Botucatu School of Medicine, UNESP, Säo Paulo State, Brazil. After receiving specific serotherapy, the patients were submitted to MR of the bite site. T1 spin-echo MRI were obtained revealing the following lesions: edema (n=9), edema associated with hemorrhage (n=5), and hemorrhage (n=1). Perimuscular areas (n=6) and subcutaneous tissues (n=5) were the most affected, followed by muscular tissues (n=4). It is important to mention that MRI did not show myonecrosis of the bite site, a widely reported finding in anatomical and histopathological experimental studies.

Studies on Brugia pahangi in inbred hamsters. 1. Susceptibility of inbred GN and APG hamsters.

The susceptibility of inbred GN and APG hamsters to Brugia pahangi infection was studied. Male GN hamsters infected subcutaneously with 100 infective larvae showed 100% patency with the average prepatent period of 69 days. The average microfilarial density was 148/40 c.mm at 26 weeks and reached 1,000/40 c.mm at days 280. The rate of adult recovery was as high as 36%. Most worms were recovered from the heart and lungs (46%) and testes (40%). The male GN hamster-B. pahangi model could be a good substitution for the jird-B. pahangi model. Female GN and male APG hamsters seemed to be less susceptible than male GN hamsters. However, they could still be a better alternative to outbred hamsters due to their high rates of patency (92 and 100%), relatively high microfilarial densities (31 and 39/40 c.mm at 26 weeks) and reasonable rates of adult recovery (23.5 and 17.2%).