  A new method of measuring long spin-lattice relaxation times ($T_1$) is
proposed. Being a single scan technique, the method is at least one order of
magnitude faster than the conventional technique. This method (Single-Scan or
Slice Selected Inversion Recovery or SSIR) relies on the slice selection
technique. The method is experimentally verified and compared with the time
taken by the conventional measurement. Furthermore, it is shown that the
conventional Inversion Recovery (IR) method which suffers from effects of r.f.
inhomogeneity can also be improved by measuring the magnetization of only a
central slice.
