The document discusses medical image compression using the 3D Discrete Hartley Transform (DHT). It provides examples of applying the DHT to compress 3D X-ray angiography (XA) images and magnetic resonance (MR) brain images. Experiments showed that an XA image could be compressed with little loss of quality using a DHT with a quantization value of M=8. An MR brain image was effectively compressed using a DHT with M=2. The DHT provides an alternative transform to the Discrete Cosine Transform for lossy 3D medical image compression.