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Updated: Oct 18, 2025
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Reliability of the freehand region-of-interest method in quantitative cerebral diffusion tensor imaging
Ullamari Hakulinen1,2,3, Antti Brander4, Tero Ilvesmäki5
1Department of Medical Physics, Medical Imaging Center of Pirkanmaa Hospital District, Tampere, Finland. ullamari.hakulinen@pshp.fi.
Background:
Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique used for evaluating changes in the white matter in brain parenchyma. The reliability of quantitative DTI analysis is influenced by several factors, such as the imaging protocol, pre-processing and post-processing methods, and selected diffusion parameters. The region-of-interest (ROI) method is most widely used of the post-processing methods because it is found in commercial software. The focus of our research was to study the reliability of the freehand ROI method using various intra- and inter-observer analyses.
Methods:
This study included 40 neurologically healthy participants who underwent diffusion MRI of the brain with a 3 T scanner. The measurements were performed at nine different anatomical locations using a freehand ROI method. The data extracted from the ROIs included the regional mean values, intra- and inter-observer variability and reliability. The used DTI parameters were fractional anisotropy (FA), the apparent diffusion coefficient (ADC), and axial (AD) and radial (RD) diffusivity.
Results:
The average intra-class correlation coefficient (ICC) of the intra-observer was found to be 0.9 (excellent). The single ICC results were excellent (> 0.8) or adequate (> 0.69) in eight out of the nine regions in terms of FA and ADC. The most reliable results were found in the frontobasal regions. Significant differences between age groups were also found in the frontobasal regions. Specifically, the FA and AD values were significantly higher and the RD values lower in the youngest age group (18-30 years) compared to the other age groups.
Conclusions:
The quantitative freehand ROI method can be considered highly reliable for the average ICC and mostly adequate for the single ICC. The freehand method is suitable for research work with a well-experienced observer. Measurements should be performed at least twice in the same region to ensure that the results are sufficiently reliable. In our study, reliability was slightly undermined by artifacts in some regions such as the cerebral peduncle and centrum semiovale. From a clinical point of view, the results are most reliable in adults under the age of 30, when age-related changes in brain white matter have not yet occurred.
Insights
The freehand region-of-interest (ROI) method in diffusion tensor imaging (DTI) shows high reliability for quantitative analysis in healthy adults. This technique is suitable for research, particularly in younger individuals, with careful observer training and repeated measurements.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Radiology
Background:
- Diffusion Tensor Imaging (DTI) is a key MRI technique for assessing white matter integrity in the brain.
- Quantitative DTI analysis reliability depends on imaging protocols, processing methods, and diffusion parameters.
- The Region-of-Interest (ROI) method is a common post-processing technique due to its availability in commercial software.
Purpose of the Study:
- To evaluate the reliability of the freehand ROI method in DTI analysis.
- To conduct intra- and inter-observer analyses to determine the consistency of measurements.
- To assess the impact of age on DTI parameters in specific brain regions.
Main Methods:
- 40 healthy participants underwent 3T brain MRI.
- Freehand ROIs were placed in nine anatomical locations.
- DTI parameters analyzed included fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD).
- Intra- and inter-observer variability and reliability were assessed using intraclass correlation coefficients (ICCs).
Main Results:
- Average intra-observer ICC was 0.9 (excellent).
- Single ICCs for FA and ADC were excellent or adequate in 8/9 regions.
- Frontobasal regions demonstrated the highest reliability.
- Younger adults (18-30 years) showed significantly different FA, AD, and RD values compared to older groups.
Conclusions:
- The freehand ROI method offers high average reliability and adequate single-measure reliability for DTI analysis.
- The method is suitable for research with experienced observers, recommending at least two measurements per region.
- Artifacts can impact reliability in certain regions (e.g., cerebral peduncle).
- Results are most clinically relevant in adults under 30 due to minimal age-related white matter changes.
