Systemic effect of benign and malignant mammary tumors on the spin-lattice relaxation time of water protons in mouse serum.

The spin-lattice relaxation time (T1) for water protons in sera was significantly (P less than 0.001) elevated above that for normal sera in mice bearing benign ductal papilloma and malignant mammary carcinoma. Serum T1 values did not differ significantly in mice with ductal hyperplasia or preneoplastic alveolar nodules. Elevated serum T1's could not be explained on the basis of serum iron levels or serum protein concentrations. This was the first report of a "systemic effect" of serum T1 elevation by a benign tumor.