Use of a high-T_c SQUID-based nuclear magnetic resonance spectrometer in magnetically unshielded environments to discriminate tumors in rats, by characterizing the longitudinal relaxation rate

This study uses a sensitive, high-T_c SQUID-detected nuclear magnetic resonance spectrometer in magnetically unshielded environments to discriminate liver tumors in rats, by characterizing the longitudinal relaxation rate, T₁^-1. The high-T_c SQUID-based spectrometer has a spectral line width of 0.9Hz in low magnetic fields. It was found that relaxation rate for tumor tissues is (3.6 ± 0.02) s ^-1 and the relaxation rate for normal tissues is (7.7 ± 0.02) s^-1. The difference in the longitudinal relaxation rates suggests that water structures around the DNA of cancer cells are different from those of normal tissues. The optimized detection sensitivity for the established system is 0.21 g at the present stage. It is concluded that T₁^-1 can be used to distinguish cancerous tissues from normal tissues. The high-T_c, SQUID-detected NMR and MRI in magnetically unshielded environments may also be useful for discriminating other tumors.