USE OF SIGNIFICANCE IMAGE TO DETERMINE PATTERNS OF CORTICAL BLOOD-FLOW ABNORMALITY IN PATHOLOGICAL AND AT-RISK GROUPS

The purpose of this work was to determine whether certain pathological groups and other groups at risk for neurological damage exhibited dis tinctive patterns of regional cerebral blood flow (rCBF) abnormality. Methods: HMPAO SPECT images obtained from six groups of subjects were compared with a normal cortical rCBF atlas, based on multivariate, vox el-by-voxel methods. In each case, a significance image was outputted, highlighting voxels with deficits of greater than or equal to 3 s.d. of normal. Abnormal patterns were examined for the six groups, which c omprised a further 40 normal volunteers, 18 diver controls, 50 divers with decompression illness (DCI), 34 boxers, 23 schizophrenics and 21 subjects with Alzheimer's disease. Results: The percentages of abnorma l cortical voxels for each group were 0.41%, 0.53%, 1.38%, 1.05%, 0.56 % and 2.24%, respectively. The percentages of images in each group wit h at least one lesion of 10 or more connected abnormal voxels and at l east 10 lesions of two or more connected voxels, respectively, were 8% and 8% (normal volunteers), 17% and 11% (diver controls), 38% and 38% (divers with DCI), 41% and 29% (boxers), 26% and 13% (schizophrenics) and 90% and 48% (subjects with Alzheimer's disease). This suggests th at multiple small lesions are as common as single large lesions for di vers with DCI but not for patients with Alzheimer's disease or schizop hrenia. Large lesions are located predominantly in the parietal and in ferior temporal regions for Alzheimer's disease, in the parietal and o ccipital regions for divers with DCI and boxers and in the inferior fr ontal region for schizophrenia. Conclusion: It appears that the groups considered here do have different rCBF patterns and that the signific ance image is a useful way of demonstrating this fact.