In an image reconstruction method for a multi-row detector computed tomography apparatus operable in a helical/spiral scan mode, a spiral reconstruction with arbitrary pitch and an improvement of the z resolution with interlaced sampling are achieved by using the known Wang reconstruction algorithm expanded by a new type of interpolation technique wherein direct and complementary projections are employed those beams of either the direct or complementary projection always being selected which exhibit the smallest distance in the z-direction from the relevant voxel to be reconstructed.