| dc.description.abstract | Más szerzők eredményeihez hasonlóan a jelen tanulmányból is kiderül, hogy a folyadékterek vizsgálatára a T2 súlyozott szekvenciák kiválóan alkalmasak. Csikók esetében azonban bebizonyosodott, hogy a növekedési zónák és az ízületi folyadék által leadott jelintenzitás-hasonlóság miatt a folyadék-porc-csont komplex ezzel a szekvenciával kevéssé informatív képet nyújt. A proton denzitás és a T1 inversion recovery szekvencia adta a leginformatívabb képet a patacsont és a nyírcsont még növekedésben levő, illetve már mineralizálódott területeiről, és teremtett optimális kontrasztviszonyokat az ízületi porc, a ligamentum impar és a synovia között a patacsont nyírcsonti ízület tájékán. Az eredményeink alapján összefoglalható, hogy vizsgálati metodikánk a patahenger rendkívül kontrasztos és részletgazdag vizsgálatát teszi lehetővé csikók számára. A protokoll tartalmaz rövid mérési idejű T1 inversion recovery szekvenciát, és a patahengert alkotó szövetek minden eddigi diagnosztikai eljárásnál precízebben ábrázolhatók csikók esetében a bursa podotrochlearis kivételével. | hu |
| dc.description.abstract | Introduction: For decades, Magnetic Resonance Imaging has been used in the human medicine and orthopaedics. Lately it has also appeared in the veterinary science. It has revolutionised the lameness diagnostic procedures of the sport horse in the past few years. Due to this imaging modality, the spectrum of the etiology of the diseases causing foot pain has been broadened to improve the diagnosis of the horses with podotrochlosis. MRI is applicable to examine the joints, the surrounding tissues and to follow their progress of growing. It is difficult to find any research about the navicular region of foals and young horses. In case of the newborn foals, severe angular deformities can develop within days because of the extremely active metabolism and the pace of the osteogenesis. These changes allow for proof of the adequate therapy. The aim of this study is to establish such a standard MRI protocol which allows the quantitative examination of the changes in the hyaline and fibro-cartilage and the subchondral bone during the endochondral ossification of the navicular bone in newborn foals. Materials and methods: We examined 6 foals (12 forelimbs, age between 0 and 52 days), 4 of which had normal posture and 2 with valgus and varus angular deformities. The examination was carried out under general anesthesia in ventral recumbency. We recorded the pictures in the 36th hour after birth, the 11th, the 22nd, the 35th and the 52nd day. First phase: On one leg, the MRI examination method was carried out using good contrast to accurately demarcate the anatomical structures of the n avicular region. The protocol contained Proton Density, T1 Inversion Recovery, T1 Spin Echo and T2 Turbo Spin Echo sequences in three different (sagittal, transversal and coronal) planes. Second phase: The applied method was performed and examined on the 12 forelimbs in the 5 different chronological moments. Third phase: The quantitative evaluation of the MRI pictures was executed in this phase. We measured the total volume of the navicular bone (A), the subchondral region (E) and the volume of the zone of mineralisation and the subchondral region together (F). From these parameters, we calculated the volume of the hyaline and fibrocartilage together (B=A-E), the zone of the mature cartilage and the zone of proliferation together (C=A-F) and the zone of degeneration (D=F-E). Finally, we counted the following ratios from the mentioned 39 parameters: A/B and C/D (counted in mm3). We then further examined if there were any degenerative disorders in the navicular region. Results: The sequences, that we used during our examination method showed the different layers of the growing navicular bone with great contrast. The synovia showed high signal intensity, while the mature cartilage zone and the zone of proliferation showed medium signal intensity on Proton Density pictures. T1 weighted Inversion Recovery sequence gave the synovia a remarkaby good contrast in the joint space. On T1 weighted Spin Echo pictures, the spongiosa shows high signal intensity in certain areas. Due to this sequence, the compact bone of the navicular bone near the flexor surface and at the insertion collateral ligament showed thinning as the bone growed. On T2 weighted Turbo Spin Echo pictures synovial cavities showed high signal intensity. It was not possible to make the podotrochlear bursa visible at any stage of the examination by any sequence. A/B and C/D ratios of normal posture foals were within a closed interval during the whole examination, while the rates of the foals with angular limb deformities were significantly different and also showed tipical patterns at different aspects. No signs of podotrochlosis was detected on any of the 12 limbs. Discussion: According to our study, T1 weighted sequences are exellent to revise liquid compartments. Also in case of foals, the growth zones and the synovia is similar in signal intensity, therefore it provides less information about the synovia-cartilage-bone complex. Proton Density and T1 weighted Inversion Recovery sequences gave the most informative images about the mineralisation and the growth zone of the distal phalanx and the navicular bone. They also showed great contrast between the synovial cartilage, the distal sesamoidean impar ligament and the synovia at the navicular region. From our results, it may be suggested, that our examination method allows a circumstantial and contrasty examination of the navicular area for foals. The protocol contains a T1 weighted Inversion Recovery with a short time of acquisition, and the tissues of the navicular region can be examined in a more precise way than other imaging modalities. | en |
