[CT and MRI diagnosis]

This section surveys the clinical usefulness of spiral-computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of thrombotic arteriovenous diseases. Spiral CT is useful to detect arterial occlusive disease by using 3D rendering, so call, "CT angiography (CTA)". 3D rendering techniques have been predominantly applied to CTA are the shaded surface display (SSD) and the maximum intensity projection (MIP). These renderings have the lacks that in an MIP no depth cues are inherent and SSD lose the majority of the scan data. The volume rendering (VR) makes up for this loss by rendering what is effectively a binary image of pixel values above the threshold. As the application of MRI in the evaluation of vascular diseases, MR angiography using time-of-flight or phase contrast techniques was performed in the past. However, according to the progress in high speed imaging method, contrast-enhanced 3D MR angiography is now used routinely and will be still more important in the diagnosis of various vascular diseases.