Comparison of manual direct and automated indirect measurement of hippocampus using magnetic resonance imaging

Abstract

Purpose: Objective quantification of brain structure can aid diagnosis and therapeutic monitoring in several neuropsychiatric disorders. In this study, we aimed to compare direct and indirect quantification approaches for hippocampal formation changes in patients with mild cognitive impairment and Alzheimer's disease (AD). Methods and materials: Twenty-one healthy volunteers (mean age: 66.2), 21 patients with mild cognitive impairment (mean age: 66.6), and 10 patients with AD (mean age: 65.1) were enrolled. All subjects underwent extensive neuropsychological testing and were imaged at 1.5 T (Vision, Siemens, Germany; T1w coronal TR = 4 ms, Flip = 13• , FOV = 250 mm, Matrix = 256 × 256, 128 contiguous slices, 1.8 mm). Direct measurement of the hippocampal formation was performed on coronal slices using a standardized protocol, while indirect temporal horn volume (THV) was calculated using a watershed algorithm-based software package (MeVis, Germany). Manual tracing took about 30 min, semi-automated measurement less than 3 min time.Results: Successful direct and indirect quantification was performed in all subjects. A significant volume difference was found between controls and AD patients (p < 0.001) with both the manual and the semi-automated approach. Group analysis showed a slight but not significant decrease of hippocampal volume and increase in temporal horn volume (THV) for subjects with mild cognitive impairment compared to volunteers (p < 0.07). A significant correlation (p < 0.001) of direct and indirect measurement was found. Conclusion: The presented indirect approach for hippocampus volumetry is equivalent to the direct approach and offers the advantages of observer independency, time reduction and thus usefulness for clinical routine.

Direct and Indirect Measurement of Temporal Horn Volume and Temporal Horn Index and its Neuropsychological Correlation in Mild Cognitive Impaired and Alzheimer Diseased Patients

“…In this study, we examined structural changes of the hippocampal formation by using two different MRI techniques: direct manual tracing on consecutive coronal slices on the one hand, and indirect semi-automated estimation via computation of the temporal horn volume (THV) on the other [11,12]. Direct volumetric measurements revealed significant atrophy of the hippocampus in AD patients when compared with healthy controls.…”

“…Assuming uniformly distributed partial volume effects Mixed Gaussians take the form of plateau curves. The model is fitted to the histogram data by minimizing squared errors [11,12].…”

“…Statistical analysis was performed using SPSS version 11 (Chicago, IL). For Mann-Whitney U, a level of significance of p < 0.05 was chosen [11,12].…”

“…This article presents different approaches for measuring the hippocampal formation using (a) region of interest (ROI) approach of image analysis, based on the a priori definition of specific brain regions and (b) a recent, newly developed technique using an indirect volumetric assessment of the temporal horn volume [10][11][12]. The direct method (a) requires highly sophisticated neuroanatomical knowledge, is very labor-and time-intensive and is unreliable due to a poor differentiation of the regions within the hippocampal formation [9], while the indirect method (b) is more user independent.…”

Tensor factorization-based classification of Alzheimer's disease vs healthy controls

“…ROI analysis focuses on specific brain regions, especially the hippocampus and the entorhinal cortex [10] [11], to show histopathological changes at early stages of AD [12]. ROI analysis of the brain structure is considered as a gold standard, but it has some drawbacks such as operator-dependency, laborand time-intensiveness, and the required step of a priori choice of regions for investigation [13]. Compared with it, more powerful techniques are proposed for analyzing sMRI data, called voxel-based morphometry(VBM) [8] [14], tensor-based morphometry [15], and source-based morphometry [16], etc.…”