Nuclear magnetic resonance imaging of mammary adenocarcinomas in the rat

Abstract
A study of 24 rats implanted in the hind leg with mammary adenocarcinomas and five shamimplanted rats, followed from the second to the eighth week postimplantation, showed nuclear magnetic resonance imaging capable of detecting all the tumors without yielding any falsepositives in the control rats. The Tl relaxation time of tumors overlapped that of muscle, and the T2 times overlapped fat, but the combination was unique when comparing tumors to muscle and fat. Necrotic regions of the tumor and the bladder contents tended to have very long T1 and T2 relaxation times. The difference in relaxation time between tumors and muscle could be accounted for in terms of water content, which was approximately 8% higher for the tumors. The study corroborates data from previous studies indicating that NMR imaging is a highly sensitive modality, although T1 and T2 times are not exclusive indicators of malignancy.