Phosphorus-31 as a Nuclear Probe for Malignant Tumors

Phosphorus-31 may prove useful as an additional nucleus for detecting malignancy by nuclear magnetic resonance. The spin-lattice relaxation times for phosphorus-31 determined by a saturation technique employing a 90°-τ-90°-τ-90° ... pulse sequence were significantly higher for two rat malignancies, Novikoff hepatoma and Walker sarcoma, and the Crocker sarcoma of mice than for normal liver, muscle, brain, kidney, and intestine tissues. No individual measurement of malignant tissues overlapped any of the measurements of normal tissues, and the probabilities of insignificance ranged from .029 for Crocker sarcoma to .000184 for Novikoff hepatoma. The phosphorus-31 nucleus, because of its strategic placement in the nucleic acid molecule, may be useful as a new probe for exploring the mechanism of carcinogenesis. The results call attention to another nucleus that may prove valuable for nuclear magnetic resonance equipment aimed at the detection of internal malignancies in humans.