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  • 1.
    Elgh, Eva
    et al.
    Umeå University, Faculty of Medicine, Community Medicine and Rehabilitation, Geriatric Medicine.
    Sundström, Torbjörn
    Umeå University, Faculty of Medicine, Radiation Sciences, Diagnostic Radiology.
    Näsman, Birgitta
    Umeå University, Faculty of Medicine, Community Medicine and Rehabilitation, Geriatric Medicine.
    Riklund Åhlström, Katrine
    Umeå University, Faculty of Medicine, Radiation Sciences, Diagnostic Radiology.
    Nyberg, Lars
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Memory functions and rCBF (99m)Tc-HMPAO SPET: developing diagnostics in Alzheimer's disease2002In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, ISSN 1619-7070, Vol. 29, no 9, p. 1140-1148Article in journal (Refereed)
    Abstract [en]

    Alzheimer's disease (AD) is a primary degenerative disease of the brain. The prevalence increases with age, with devastating consequences for the individual and society. The aim of this study was to evaluate whether patients with early AD show an altered regional cerebral blood flow (rCBF) compared with control persons. Furthermore, we aimed to investigate the correlation between rCBF in sublobar volumes of the brain and performance on memory tests. Memory tests were chosen to evaluate episodic and semantic memory. Fourteen patients (aged 75.2+/-8.8 years) with early AD and 15 control persons (aged 71.4+/-3.2 years) were included. rCBF measurements with single-photon emission tomography (SPET) using technetium-99m hexamethylpropylene amine oxime (HMPAO) were performed. The rCBF (99m)Tc-HMPAO SPET images were spatially transformed to fit a brain atlas and normalised for differences in rCBF (Computerised Brain Atlas software). Cortical and subcortical volumes of interest (VOIs) were analysed and compared. Compared with the controls, AD patients showed a significantly lower rCBF ratio in temporoparietal regions, including the left hippocampus. The diagnostic sensitivity and specificity for AD were high in temporoparietal regions. AD patients had significantly reduced performance on semantic and, in particular, episodic memory tests compared with age-matched normative data, and their performance on several episodic tests correlated with rCBF ratios in parietal and temporal regions, including the left hippocampus. The correlation between rCBF ratio and level of episodic memory performance suggests that abnormalities in rCBF pattern underlie impaired episodic memory functioning in AD.

  • 2.
    Larsson, Anne
    et al.
    Umeå University, Faculty of Medicine, Radiation Sciences, Radiation Physics.
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Radiation Sciences, Radiation Physics.
    Sundström, Torbjörn
    Umeå University, Faculty of Medicine, Radiation Sciences, Diagnostic Radiology.
    Riklund Åhlström, Katrine
    Umeå University, Faculty of Medicine, Radiation Sciences, Diagnostic Radiology.
    A method for attenuation and scatter correction of brain SPECT based on computed tomography images2003In: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 24, no 4, p. 411-420Article in journal (Refereed)
    Abstract [en]

    A method for attenuation and scatter correction of brain single photon emission computed tomography (SPECT) is described where computed tomography (CT) images of the brain are used for the calculation of attenuation maps. The method is evaluated for the substance 99mTc hexamethylpropylene amine oxime. A transmission dependent scatter correction is utilized and is based on ray sums calculated through the attenuation map. A method based on external markers is used to align the SPECT and CT image volumes. The markers need only to be present during the SPECT acquisition since the corresponding landmarks can be found without markers on the CT images. The mismatching has been investigated for five patients who have undergone both a CT examination and a SPECT examination with markers. Twelve individuals from the staff have pointed out the landmarks on the CT images, with an average standard deviation of 3.4 mm. Reconstructions with an attenuation map shifted the corresponding 95% confidence interval have been performed to obtain an estimation of the quantitative uncertainty caused by the mismatching, and quantitative errors of up to 6.3% have been measured. At present the method is probably most useful when groups of patients are studied.

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