Voxel similarity measures for 3-D serial MR brain image registration.

We have evaluated eight different similarity measures used for rigid body registration of serial magnetic resonance (MR) brain scans. To assess their accuracy we used 33 clinical three-dimensional (3-D) serial MR images, with deformable extradural tissue excluded by manual segmentation and simulated 3-D MR images with added intensity distortion. For each measure we determined the consistency of registration transformations for both sets of segmented and unsegmented data. We have shown that of the eight measures tested, the ones based on joint entropy produced the best consistency. In particular, these measures seemed to be least sensitive to the presence of extradural tissue. For these data the difference in accuracy of these joint entropy measures, with or without brain segmentation, was within the threshold of visually detectable change in the difference images.

The identification of cerebral volume changes in treated growth hormone-deficient adults using serial 3D MR image processing.

PURPOSE: A pilot study to detect volume changes of cerebral structures in growth hormone (GH)-deficient adults treated with GH using serial 3D MR image processing and to assess need for segmentation prior to registration was conducted. METHOD: Volume MR scans of the brain were obtained in five patients and six control subjects. Patients were scanned before and after 3 and 6 months of therapy. Control subjects were scanned at the same intervals. A phantom was used to quantify scaling errors. Second and third volumes were aligned with the baseline by maximizing normalized mutual information and transformed using sinc interpolation. Registration was performed with and without brain segmentation and correction of scaling errors. Each registered, transformed image had the original subtracted, generating a difference image. Structural change and effects of segmentation and scaling error correction were assessed on original and difference images. The radiologists' ability to detect volume change was also assessed. RESULTS: Compared with control subjects, GH-treated subjects had an increase in cerebral volume and reduction in ventricular volume (p = 0.91 x 10(-3)). Scale correction and segmentation made no difference (p = 1 and p = 0.873). Structural changes were identified in the difference images but not in the original (p = 0.136). The radiologists detected changes >200 microm. CONCLUSION: GH treatment in deficient patients results in cerebral volume changes detectable by registration and subtraction of serial MR studies but not by standard assessment of images. This registration method did not require prior segmentation.

Technical information for architects.

The Building Research Station (BRS) financed a research contract at the York Institute of Advanced Architectural Studies to try and improve their means of communication with architects, as it was felt that the results of much building research were not being used. Alternative methods of presenting information in research papers were sent to selected architects' offices. Two interview surveys were conducted, to establish architects' attitudes to and requirements from research information, and to took at the context into which that information fitted: the architect's office. Two postal surveys were also carried out. Broadly, architects want their technical literature to be tailored to their situation. They want the use of architectural convection and language whenever possible. Visually trained themselves, they show a heavy preference for papers with a high content of visual material, particularly in the form of architectural and scaled drawings. Papers should be brief and to the point, and should leave out the experimental orientation which is sometimes the concomitant of conventional research papers. The findings and the design recommendations may be relevant for others needing similar design reference material, such as industrial designers and engineers.