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- Aguilar, C., et al.
(author)
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Automated CT-based segmentation and quantification of total intracranial volume
- 2015
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 25:11, s. 3151-3160
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Journal article (peer-reviewed)abstract
- Objectives To develop an algorithm to segment and obtain an estimate of total intracranial volume (tICV) from computed tomography (CT) images. Materials and methods Thirty-six CT examinations from 18 patients were included. Ten patients were examined twice the same day and eight patients twice six months apart (these patients also underwent MRI). The algorithm combines morphological operations, intensity thresholding and mixture modelling. The method was validated against manual delineation and its robustness assessed from repeated imaging examinations. Using automated MRI software, the comparability with MRI was investigated. Volumes were compared based on average relative volume differences and their magnitudes; agreement was shown by a Bland-Altman analysis graph. Results We observed good agreement between our algorithm and manual delineation of a trained radiologist: the Pearson's correlation coefficient was r = 0.94, tICVml[manual] = 1.05 x tICVml[automated] - 33.78 (R-2 = 0.88). Bland-Altman analysis showed a bias of 31 mL and a standard deviation of 30 mL over a range of 1265 to 1526 mL. Conclusions tICV measurements derived from CT using our proposed algorithm have shown to be reliable and consistent compared to manual delineation. However, it appears difficult to directly compare tICV measures between CT and MRI.
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- Cavallin, L, et al.
(author)
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Can dynamic susceptibility contrast magnetic resonance imaging replace single-photon emission computed tomography in the diagnosis of patients with Alzheimer's disease? A pilot study
- 2006
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In: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 47:9, s. 977-985
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Journal article (peer-reviewed)abstract
- Purpose: To compare single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer's disease (AD). Material and Methods: Twenty-four patients, eight with AD, 10 with MCI, and six controls were investigated with SPECT using 99mTc-hexamethylpropyleneamine oxime (HMPAO) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with gadobutrol. Three observers performed a visual interpretation of the SPECT and MR images using a four-point visual scale. Results: SPECT was superior to DSC-MRI in differentiating normal from pathological. All three observers showed statistically significant results in discriminating between the control group, AD, and MCI by SPECT, with a P value of 0.0006, 0.04, and 0.01 for each observer. The statistical results were not significant for MR ( P values 0.8, 0.1, and 0.2, respectively). Conclusion: DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer's disease. Several patient- and method-related improvements should be made before this method can be recommended for clinical practice.
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- Cavallin, L, et al.
(author)
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Overtime reliability of medial temporal lobe atrophy rating in a clinical setting
- 2012
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In: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 53:3, s. 318-323
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Journal article (peer-reviewed)abstract
- Medial temporal lobe atrophy (MTA) is one of the first magnetic resonance imaging (MRI) signs in patients with Alzheimer's disease (AD) and used as a measure of disease progression. Visual assessment of MTA is easy to perform but the reliability of MTA rating over time has not been studied. Purpose To investigate what happens to the MTA rating scores if two radiologists rate the same MRI scans six times over a period of 1 year. Material and Methods One hundred outpatients were included in this study. All patients underwent MRI with a protocol and sequences used for geriatric patients, according to local clinical standards. One neuroradiologist and one general radiologist independently of each other performed retrospective visual assessments of MTA six times, using the same scans, over a period of 1 year. Results Intra-rater kappa varied between κ 0.65 and 0.84 for the neuroradiologist and κ 0.38 and 0.74 for the general radiologist. Intra-rater weighted kappa (wκ) values showed almost perfect agreement for both investigators (wκ 0.83–0.94). Inter-rater reliability showed fair to moderate agreement, with the kappa value varying from κ 0.29 to 0.48 and weighted kappa values ranging from wκ 0.72 to 0.84. There was a statistically significant difference in rating between the two investigators. Conclusion Visual assessment of MTA repeated over time has a high grade of reproducibility when performed by an experienced investigator. The reproducibility drops when assessment is rarely performed. Inter-rater reliability is low when two investigators not working together are compared.
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- Cavallin, L, et al.
(author)
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Voxel-based correlation between coregistered single-photon emission computed tomography and dynamic susceptibility contrast magnetic resonance imaging in subjects with suspected Alzheimer disease
- 2008
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In: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 49:10, s. 1154-1161
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Journal article (peer-reviewed)abstract
- Background: Current diagnosis of Alzheimer disease is made by clinical, neuropsychologic, and neuroimaging assessments. Neuroimaging techniques such as magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) could be valuable in the differential diagnosis of Alzheimer disease, as well as in assessing prognosis. Purpose: To compare SPECT and MRI in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer disease (AD). Material and Methods: 24 patients, eight with AD, 10 with MCI, and six controls, were investigated with SPECT using 99mTc-hexamethylpropyleneamine oxime (HMPAO, Ceretec; GE Healthcare Ltd., Little Chalsont UK) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with a contrast-enhancing gadobutrol formula (Gadovist; Bayer Schering Pharma, Berlin, Germany). Voxel-based correlation between coregistered SPECT and DSC-MR images was calculated. Region-of-interest (ROI) analyses were then performed in 24 different brain areas using brain registration and analysis of SPECT studies (BRASS; Nuclear Diagnostics AB, Stockholm, Sweden) on both SPECT and DSC-MRI. Results: Voxel-based correlation between coregistered SPECT and DSC-MR showed a high correlation, with a mean correlation coefficient of 0.94. ROI analyses of 24 regions showed significant differences between the control group and AD patients in 10 regions using SPECT and five regions in DSC-MR. Conclusion: SPECT remains superior to DSC-MRI in differentiating normal from pathological perfusion, and DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer disease.
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- Oksengard, A. R., et al.
(author)
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Lack of Accuracy for the Proposed 'Dubois Criteria' in Alzheimer's Disease: A Validation Study from the Swedish Brain Power Initiative
- 2010
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In: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 30:4, s. 374-380
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Journal article (peer-reviewed)abstract
- Background/Aims: Our purpose was to investigate whether the new research criteria for Alzheimer's disease proposed in 2007 by Dubois et al. are valid in a naturalistic memory clinic sample. Method: Retrospective diagnostic analyses were carried out to compare the traditional diagnostic criteria for dementia with the new criteria suggested by Dubois et al. No patient had gone through all procedures postulated as additional features in the proposed new Dubois criteria. Material: Two independent experienced geriatricians re-examined 150 complete patients' records. The study physicians were blinded to any of the results of the core and additional features suggested by Dubois et al. to avoid circular diagnostic bias. Results: Among our 96 patients with a clinical diagnosis of subjective cognitive impairment and/or mild cognitive impairment, 2 of the patients with subjective cognitive impairment and 5 patients with mild cognitive impairment would classify as pre-dementia Alzheimer's disease according to the Dubois criteria. In our 23 Alzheimer patients diagnosed clinically, only 12 of the cases fulfilled the criteria for Alzheimer's disease suggested by Dubois et al. Interpretation: The proposed new criteria for Alzheimer's disease are valid in 55% of our patients clinically diagnosed as having full-blown Alzheimer dementia. Additionally, 7.3% 'true' Alzheimer cases will be identified in a group of 96 clinically non-demented patients. Our results show that there is a large heterogeneity in a clinical naturalistic sample of patients with an Alzheimer phenotype. Conclusion: There is a need to further validate the currently existing biomarkers in large unselected samples and avoid the pitfall of workup bias and circular diagnostic processes. Additionally, valid age-specific cut-off values for the diagnostic markers in question have to be defined. Copyright (C) 2010 S. Karger AG, Basel
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