New technique for visualizing cerebral vessels in MR angiographic images using three-dimensional discrete wavelet transform.

Visualization techniques for magnetic resonance (MR) angiographic images are generally based on the projection ray concept; for example, maximum intensity projection (MIP) and volume rendering (VR). A new technique based on a different concept from projection rays is explored in this study: three-dimensional (3-D) discrete wavelet transforms are used for visualizing cerebral vessels in the MR angiographic image. This technique successfully visualizes cerebral vessels and represents the spatial relationship between the cerebral vessels, as in the case of VR. The proposed technique is, thus, indicated to be promising for visualizing cerebral vessels in 3-D MR angiographic images.

The application of a new predictive technique for lossless compression of medical images.

A new predictive technique for lossless compression is applied to CT and MR images in order to achieve high compression in the lossless mode. To accomplish this, a prediction value was obtained by assuming the horizontal and vertical components of each pixel. Wide and narrow predictive coding modes were adaptively selected to achieve an accurate prediction. The performance of the predictive technique was compared with the performance of four representative compression techniques in the lossless mode, using different types of CT and MR image sets with different bit rates. Overall, the proposed predictive technique yielded the best compression, particularly with the lower bit-rate images tested. While the compression results are largely dependent on the images used, the results confirm the strong potential of the proposed predictive technique as a strategy for obtaining high lossless-compression in medical images.