A computerized human reference brain for rCBF/SPET technetium-99m exametazime (HMPAO) investigation of elderly.

Using the bull's eye approach, a reference brain from the single photon emission tomography (SPET) images of 10 subjects aged 62-81 years with excellent mental and physical health was constructed. SPET images were acquired twice, 1 week apart, using a single detector rotating gamma camera collecting 64 planar images over a 360 degrees orbit. The centre of each transaxial slice was first defined with an automatic edge detecting algorithm applied to an anterior-posterior and a side profile of the brain. Each slice was divided into 40 sectors. Maximum counts/pixel in each sector was picked. The 40 maximum count values from one transaxial slice were allowed to form a horizontal row in a new parametric image on the x-axis and slice number from the vertex to the basal parts of the brain on the y-axis. This new image was scaled to a 64 x 16 pixel matrix by interpolation, which meant a normalization of all studies to the same size. The parametric image in each subject was scaled with regard to intensity by a factor calculated by a normalization procedure using the least squares analysis. Mean and SD for each pixel were calculated, thereby constructing a "mean parametric image", and a "SD parametric image". These two images are meant to be used as the reference brain for evaluation of patient studies. This method can be used for objective measurements of diffuse brain changes and for pattern recognition in larger groups of patients. Statistical multifactorial analysis of parameters used for acquisition and data processing is possible.

HMPAO SPECT in Parkinson's disease (PD) with major depression (MD) before and after antidepressant treatment.

Previously we suggested that major depression (MD) in Parkinson's disease (PD) could be an indication of a more advanced and widespread neurodegenerative process, as PD symptoms were more severe in those with depression. We also found a different antidepressant response with SSRI medication in PD patients with depression compared to depressed patients without PD. This indicates diverse underlying pathophysiological mechanisms. Investigations using single-photon emission computed tomography (SPECT), measuring regional cerebral blood flow (rCBF), may contribute to enlighten the neurobiological substrates linked to depressive symptoms. SPECT was performed in order to compare rCBF in MD patients with and without PD. The study included 11 MD patients with PD, 14 non-depressed PD patients and 12 MD patients without PD. All patients were followed for 12 weeks with repeated evaluation of depressive as well as PD symptoms. Anti-Parkinsonian treatment remained unchanged during the study. Antidepressant treatment with SSRI (citalopram) was given to all patients with MD. SPECT was performed before and after 12 weeks of antidepressant treatment. rCBF was found to differ between PD patients with and without MD, as well as between MD patients with and without PD, both at baseline and concerning the response to treatment with SSRI (citalopram). In patients with PD the rCBF was found to be decreased in preoccipital and occipital regions, a finding more common when PD was combined with MD. In summary, larger cortical areas were found to be involved in depressed PD patients, both with hyperactivity (reciprocal to basal degeneration in PD and maybe dopaminergic treatment) and with hypoactivity (probably due to organic lesions leading to hypoperfusion). These observations support our hypothesis that PD combined with MD is an expression of a more advanced and widespread neurodegenerative disorder.