A review of the magnetic resonance response of biological tissue and its applicability to the diagnosis of cancer by NMR radiology.

It is now possible to produce cross-sectional NMR images of humans on a routine basis (52-54). Furthermore, there is a growing body of evidence from studies in vitro indicating that cancerous tissue has a significantly different NMR response from healthy tissue. Provided sufficient knowledge of the density, relaxation times, and their interrelation is available, then the technique of NMR radiology may with care be optimized to give considerable improvement over existing techniques in soft tissue discrimination and tumor detection. However, the first-order correlation of relaxation times with water density does raise the question of the uniqueness of diagnosis. Furthermore, the extrapolation of in vitro measurements to the situation in vivo is seen to be complicated by such factors as blood content, muscle and fluid motion, contributions from fat, and fluid in tissue spaces. Considerable study is required in vivo to resolve these uncertainties.