We introduced a new vector quantizer (VQ) for the compression of digital image sequences. Our approach unifies both efficient coding method: a fast lattice encoding and an unbalanced tree-structured codebook design according to a distortion vs. rate tradeoff. This tree-structured lattice VQ (TSLVQ) is based on the hierarchical packing of embedded truncated lattices. Now we investigate the determination of the most efficient lattice respectively to this method. We also describe a fast test which permits to detect the input vectors whose norm is above than the maximum allowed by the TSLVQ. Finally we analyze experimental results applied to image sequence with our VQ taking place in a region-based coding scheme for a videophone application.