Today, modern imaging procedures complete the studies of the body with scalpel and tweezers. By this development a lot of new opportunities both in diagnostic and in therapeutic practice came up. The non-invasive techniques are rapidly accepted in medicine and veterinary medicine. Indeed, the veterinary medicine profits from the rapid development in human radiology. Due to the permanent improvement in the MRI, equipments are often renewed. Therefore a quite expensive technology may be available to the veterinary medicine in close future. Thus the standard in the field of research as well as diagnosis and therapy of small animals has clearly risen. As a consequence, modern imaging methods are also a part in veterinary education. In order to interpret the images obtained, solid knowledge of the two-dimensional normal anatomy becomes very important for veterinarians. On CT and MR pictures, the radiologist is confronted with detailed anatomical sections instead of two- dimensional shadow pictures as on conventional radiographs. These new developments have caused difficulties when evaluating CT and MR images. The knowledge of the normal topographical and applied anatomy has to serve as a basis for recognizing structural details. This paper contributes to the great need for more investigations in this field, particularly on the detailed cross-sectional anatomy of the cat as seen on MR images. Five adult cats of different age and sex were imaged with a "Siemens Magnetom GBS II" with a commercial extremities coil in the Department of Radiology of the "Universitätsklinikum Benjamin Franklin der Freien Universität Berlin". The cats were placed in a ventral or dorsal recumbent position. To prevent motion artefacts the animals were anaesthesized by means of an intramuscularly administered Ketamin-Rompun injection . The MRI-studies were performed using horizontal, transverse and saggital scanning with a slice thickness of 3 mm. T1-weighted sequences gave the best results for anatomical description. For comparison, frozen sections of other 5 cats in corresponding layer orientations were made in approximately 0,5-1 cm intervals with a bandsaw and immediately photographed. Anatomical structures on MR images and frozen slices were marked by lines which were labeled according the Nomina anatomica veterinaria. MR pictures and frozen slices clearly delineated the abdominal organs and large blood vessels. Motion artefacts appear more in the upper abdominal region due to the proximity of the heart and respiratory motion of the diaphragm. 3-D-reconstruction of a series of images enables the presentation of the course of the big blood vessels in the abdomen. In general T1-weighted sequences showed clearly delineated structures. The liver, spleen and kidneys were visualized with good contrast of the parenchyma and blood vessels and medulla/cortex respectively. The alimentary canal was delineated also well with good contrast between the intestine wall, surrounding fat and the intestinal content. Interesting anatomical structures in the living cat could be presented like the often controversially discussed "Impressio renalis". The inherent high level of soft tissue contrast makes MRI a highly sensitive and specific modality for detection of normal anatomical structures of the cat.
