THE CLIFFORD-PATERSON-LECTURE, 1993 - ACCURATE MEASUREMENT IN IN-VIVOMAGNETIC-RESONANCE - AN ENGINEERING PROBLEM

Measurement in in vivo magnetic resonance - both in imaging and spectr oscopy - has proved to be a much more intractable problem than extrapo lation from conventional high resolution studies might have suggested. Although this paper concentrates mainly on some of the complications of magnetic resonance imaging, the same conceptual difficulties (compo unded by much reduced signal levels) affect in vivo spectroscopy. Tiss ue is an extremely complex system and many of the difficulties studyin g it arise from the interactions that are unintentionally engendered w hen it is observed. Patient motion is a potent source of artifact to t he technical challenge of making better measurements, and different fo rms of motion are likely to be the ultimate limitation on the sensitiv ity and discrimination of the technique as a whole. In this context it is observed that the traditional criterion of performance - system si gnal-to-noise ratio - should be replaced by a signal-to-artifact estim ate, and that this may affect the design and implementation of detecto r systems to a significant extent.