| 1. |
- Ambarki, Khalid, et al.
(författare)
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Evaluation of Automatic Measurement of the Intracranial Volume Based on Quantitative MR Imaging
- 2012
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Ingår i: American Journal of Neuroradiology. - : American Society of Neuroradiology. - 0195-6108 .- 1936-959X. ; 33:10, s. 1951-1956
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Brain size is commonly described in relation to ICV, whereby accurate assessment of this quantity is fundamental. Recently, an optimized MR sequence (QRAPMASTER) was developed for simultaneous quantification of T1, T2, and proton density. ICV can be measured automatically within minutes from QRAPMASTER outputs and a dedicated software, SyMRI. Automatic estimations of ICV were evaluated against the manual segmentation. MATERIALS AND METHODS: In 19 healthy subjects, manual segmentation of ICV was performed by 2 neuroradiologists (Obs1, Obs2) by using QBrain software and conventional T2-weighted images. The automatic segmentation from the QRAPMASTER output was performed by using SyMRI. Manual corrections of the automatic segmentation were performed (corrected-automatic) by Obs1 and Obs2, who were blinded from each other. Finally, the repeatability of the automatic method was evaluated in 6 additional healthy subjects, each having 6 repeated QRAPMASTER scans. The time required to measure ICV was recorded. RESULTS: No significant difference was found between reference and automatic (and corrected-automatic) ICV (P greater than .25). The mean difference between the reference and automatic measurement was -4.84 +/- 19.57 mL (or 0.31 +/- 1.35%). Mean differences between the reference and the corrected-automatic measurements were -0.47 +/- 17.95 mL (-0.01 +/- 1.24%) and -1.26 +/- 17.68 mL (-0.06 +/- 1.22%) for Obs1 and Obs2, respectively. The repeatability errors of the automatic and the corrected-automatic method were less than1%. The automatic method required 1 minute 11 seconds (SD = 12 seconds) of processing. Adding manual corrections required another 1 minute 32 seconds (SD = 38 seconds). CONCLUSIONS: Automatic and corrected-automatic quantification of ICV showed good agreement with the reference method. SyMRI software provided a fast and reproducible measure of ICV.
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| 2. |
- Vågberg, Mattias, et al.
(författare)
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Automated Determination of Brain Parenchymal Fraction in Multiple Sclerosis
- 2013
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Ingår i: American Journal of Neuroradiology. - : American Society of Neuroradiology. - 0195-6108 .- 1936-959X. ; 34:3, s. 498-504
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Brain atrophy is a manifestation of tissue damage in MS. Reduction in brain parenchymal fraction is an accepted marker of brain atrophy. In this study, the approach of synthetic tissue mapping was applied, in which brain parenchymal fraction was automatically calculated based on absolute quantification of the tissue relaxation rates R1 and R2 and the proton attenuation. MATERIALS AND METHODS: The BPF values of 99 patients with MS and 35 control subjects were determined by using SyMap and tested in relationship to clinical variables. A subset of 5 patients with MS and 5 control subjects were also analyzed with a manual segmentation technique as a reference. Reproducibility of SyMap was assessed in a separate group of 6 healthy subjects, each scanned 6 consecutive times. RESULTS: Patients with MS had significantly lower BPF (0.852 0.0041, mean +/- SE) compared with control subjects (0.890 +/- 0.0040). Significant linear relationships between BPF and age, disease duration, and Expanded Disability Status Scale scores were observed (P less than .001). A strong correlation existed between SyMap and the reference method (r = 0.96; P less than .001) with no significant difference in mean BPF. Coefficient of variation of repeated SyMap BPF measurements was 0.45%. Scan time was less than6 minutes, and postprocessing time was less than2 minutes. CONCLUSIONS: SyMap is a valid and reproducible method for determining BPF in MS within a clinically acceptable scan time and postprocessing time. Results are highly congruent with those described using other methods and show high agreement with the manual reference method.
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| 3. |
- Vågberg, Mattias, et al.
(författare)
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Brain parenchymal fraction in an age-stratified healthy population : determined by MRI using manual segmentation and three automated segmentation methods
- 2016
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Ingår i: Journal of neuroradiology. - : Masson Editeur. - 0150-9861 .- 1773-0406. ; 43:6, s. 384-391
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Brain atrophy is a prominent feature in many neurodegenerative diseases, such as multiple sclerosis, but age-related decrease of brain volume occurs regardless of pathological neurodegeneration. Changes in brain volume can be described by use of the brain parenchymal fraction (BPF), most often defined as the ratio of total brain parenchyma to total intracranial space. The BPF is of interest both in research and in clinical practice. To be able to properly interpret this variable, the normal range of BPF must be known. The objective of this study is to present normal values for BPF, stratified by age, and compare manual BPF measurement to three automated methods. MATERIALS AND METHODS: The BPFs of 106 healthy individuals aged 21 to 85 years were determined by the automated segmentation methods SyMap, VBM8 and SPM12. In a subgroup of 54 randomly selected individuals, the BPF was also determined by manual segmentation. RESULTS: The median (IQR) BPFs of the whole study population were 0.857 (0.064), 0.819 (0.028) and 0.784 (0.073) determined by SyMap, VBM8 and SPM12, respectively. The BPF decreased with increasing age. The correlation coefficients between manual segmentation and SyMap, VBM8 and SPM12 were 0.93 (P<0.001), 0.77 (P<0.001) and 0.56 (P<0.001), respectively. CONCLUSIONS: There was a clear relationship between increasing age and decreasing BPF. Knowledge of the range of normal BPF in relation to age group will help in the interpretation of BPF data. The automated segmentation methods displayed varying degrees of similarity to the manual reference, with SyMap being the most similar.
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