A new technique for gas temperature determination in fusion plasmas based on time- and space-resolved imaging interferometry is presented. The proposed imaging interferometer includes a multi-channel optical fiber bundle, a pair of flat mirrors, collimating lenses, and a fast camera for registration of interferometry fringes. The technique is applied for ion temperature measurements in the Versatile Experiment Spherical Torus (VEST) tokamak located at the Seoul National University. The multi-channel operation regime of the interferometer is studied by simulations. The first experimental two-channel results obtained using the Hα emission line from the VEST plasma edge are presented and analyzed. The mentioned apparatus is suggested to be especially useful for the multi-point time-resolved characterization of the non-repetitive processes in low-temperature regions of fusion plasmas.