CORRELATIONS OF RADIOLOGICAL IMAGES WITH GROSS ANATOMY Department of Anatomy and Neurobiology, Faculty of Medicine, Sir Charles Tupper Building, Dalhousie University, Halifax, Nova Scotia. B3H 4H7 I.G.Mobbs, Department of Anatomy and Neurobiology, Dalhousie University, Canada. INTRODUCTION The following modules are an introduction to various imaging techniques (X-ray, CT scanning, MRI, Ultrasound) used to display human anatomy. It is a beginning in the integration of basic anatomy with clinical studies. The modules will follow the regions covered each week in the case and will be useful in interpreting the images provided in some of the cases. This is not a program for you to become a radiologist, rather think of it as the first of many steps for using and interpreting basic sciences into your clinical studies. It is another way of looking at human anatomy and you will build on this in subsequent units and years. In these modules X-ray film, Computer Tomography (CT), Magnetic Resonance Imaging and Ultrasound will be presented and related to gross anatomical specimens that you will see in the dissecting room so there is opportunity to figure out relationships on specimens. In X-ray imaging, X-rays pass through the body either from anterior to posterior (AP), posterior to anterior (PA) or laterally. Remember that no matter which direction structures will be superimposed on each other making interpretation difficult. In addition, the image seen is in two dimensions so that you must become familiar with translating into three dimensions, hence the need to relate the material to the cadaver and prosections. Imaging with computer tomography produces cross-sectional images presented on a grey scale. X-rays are "sprayed" from a source through selected consecutive levels of the body and the resultant attenuation of the x-rays coming out of the specific sections are received by small detectors situated opposite the source. A computer analyses the different densities of x-rays coming from different tissues and displays a cross-section of the body at the selected levels. MRI displays a similar grey scale cross-sectional image of regions of the body, however, the image is achieved by the attenuation of radio waves by properties of different tissues. The end result of both of these techniques is a cross-sectional image through a thin slice of the body. These images are quite difficult to interpret and you would normally use a series of cross-sections in your interpretations. This is not possible in these short modules but the images have been related to embalmed cross-sections of a cadaver and to other prosections. This section provides a more technological description of the methods used to obtain images. It is not necessary at this stage to spend time on this. Magnetic Resonance Imaging and Computer Tomography References.
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