Image Processing of Routine Spin-Echo MR Images to Enhance Vascular Structures: Comparison with MR Angiography

Magnetic Resonance Imaging (MRI) is a highly flexible diagnostic imaging technique providing complex information about the morphology of various normal and abnormal tissues. Besides this clinically valuable anatomic and pathologic information, there are some unique functional features which can be extracted from MR images. The influence of macroscopic and microscopic motion on MR images as revealed by more or less specialized pulse sequences may demonstrate the presence of physiologically important processes such as blood or cerebrospinal fluid (CSF) flow, tissue perfusion and diffusion [Axel84, Demoulin87, Demoulin89, Haacke89, Wehrli87]. Recent progress in the implementation of these MRI methods shows that while these applications have not yet been fully exploited, their use in clinical practice is not far in the future.The use of image processing techniques can definitely improve the visualization, display and interpretation of MR images. The computerized post-processing techniques may also have a very significant role in accessing the physiologic information available from MRI. In this work we applied image processing techniques to both routine, standard spin-echo MR acquisitions and to MR angiograms (MRA) in order to extract and display vascular structures with intraluminal flow. We demonstrated that it is possible to segment a standard spin-echo data set into brain parenchyma (white and gray matter), cerebrospinal fluid (CSF) and vascular structures. The segmented images can be displayed using 3D surface rendering and selective clipping. The extracted vascular structures obtained with the MRI and MRA methods were compared.While the vessels were better delineated by the MRA method, especially after image processing, the major morphologic features were also accessible after segmentation of the standard spin-echo images.