2 The Measurement Process : MR Data Collection and Image Analysis

The subject is positioned on the scanner couch by the radiographer (technologist). The subject should be comfortable, to reduce movement during the scan as much as possible. The radiographer should use their insight into the subject’s emotional state to reduce anxiety if necessary; preparation on a separate couch may be helpful. A cushion under the knees can reduce cramp. Occasionally it is desirable to place the subject prone. Prone positioning of the head may be more comfortable if support is provided for the forehead and cheekbones, leaving a gap for the nose, as used in a massage table. Movement of the body can cause a head movement; a nasal positioning device (Tofts et al., 1990) can help cooperative subjects to keep still. Some patients will find it hard to keep still because of their disease. Study investigators are usually motivated to keep very still. Some