Comparison of manual and semi-automated delineation of regions of interest for radioligand PET imaging analysis

BACKGROUND As imaging centers produce higher resolution research scans, the number of man-hours required to process regional data has become a major concern. Comparison of automated vs. manual methodology has not been reported for functional imaging. We explored validation of using automation to delineate regions of interest on positron emission tomography (PET) scans. The purpose of this study was to ascertain improvements in image processing time and reproducibility of a semi-automated brain region extraction (SABRE) method over manual delineation of regions of interest (ROIs). METHODS We compared 2 sets of partial volume corrected serotonin 1a receptor binding potentials (BPs) resulting from manual vs. semi-automated methods. BPs were obtained from subjects meeting consensus criteria for frontotemporal degeneration and from age- and gender-matched healthy controls. Two trained raters provided each set of data to conduct comparisons of inter-rater mean image processing time, rank order of BPs for 9 PET scans, intra- and inter-rater intraclass correlation coefficients (ICC), repeatability coefficients (RC), percentages of the average parameter value (RM%), and effect sizes of either method. RESULTS SABRE saved approximately 3 hours of processing time per PET subject over manual delineation (p 0.8) for both methods. RC and RM% were lower for the manual method across all ROIs, indicating less intra-rater variance across PET subjects' BPs. CONCLUSION SABRE demonstrated significant time savings and no significant difference in reproducibility over manual methods, justifying the use of SABRE in serotonin 1a receptor radioligand PET imaging analysis. This implies that semi-automated ROI delineation is a valid methodology for future PET imaging analysis

Mr volumetry study of hippocampus and temporal lobe in malay adults with normal mri brain in HUSM

Introduction: Volumetry of hippocampus and temporal lobe has been paid attention more and more along with advanced in MRI. Magnetic resonance imaging (MRI) is a non-invasive and provides detailed, accurate morphology of hippocampus and also temporal lobe. MR volumetry of these two structures is important as they are affected by several disease processes. Establishing a normative data for a population is essential so as to refer and diagnose particular illness. There are computer aided automated and semi-automated method available for MR volumetry. This study used manual method for the normative data of hippocampus and temporal lobe. Volumetric MRI analysis is more sensitive than T2-weighted imaging to atrophy associated with hippocampal sclerosis. It also distinguish volume loss from space occupying lesion as well as may predict a good prognosis following surgery for epilepsy (Bronen, Cheung et al. 1991). The purpose of this study is to obtain hippocampal and temporal lobes volumes in normal Malay adults as a normative database. Hence, it can be a reference in diagnosing diseases related with these two structures. Objectives: The aims of this study is to determine the volume of hippocampus and temporal lobe in Malay adult with normal MRI brain. Methods and materials: This was a cross sectional observational study to determine volume of hippocampus and temporal lobe in Malay adult with normal MRI brain. The age of the patients was range from 21 to 49 years old. The study period was from February 2008 until June 2009 and 51 subjects were included. Majority of them were normal volunteers, and some were patients who had normal MRI brain. MRI of brain and temporal lobe series were performed using a Signa Horizon LX 1.0 Tesla from the Generic Electric Company. Oblique coronal sections perpendicular to the axis of hippocampus were done with 4mm slice thickness and 1mm gap. T1, T2, FLAIR and SPGR series were done. Hippocampal and temporal lobevolumetry were performed. The mean and standard deviation (SD) of hippocampus and temporal lobe volume were calculated using SPSS version 17. Results: Mean and standard deviation of the total hippocampus volume of normal adult was 6.43 cm3 (0.80) for all subjects. Mean total hippocampus volume was 6.62 cm3 (0.87) in male and 6.27 cm3 (0.71) for female. Mean and standard deviation of hippocampus were 3.35 cm3 (0.46) on the right and 3.01 cm3 (0.45) on the left side. Mean hippocampal volume for the right side for male subjects is ranging from 3.21 cm3 (0.44) to 3.54 cm3 (0.35) and for the left side is from 2.95 cm3 (0.30) to 3.32 cm3 (0.42). Mean hippocampal volume for the right side for female subjects is ranging from 3.07 cm3 (0.47) to 3.42 cm3 (0.30) and for the left side is from 2.80 cm3 (0.36) to 3.08 cm3 (0.25). Mean total temporal lobe volume for all subjects was 161.28 cm3 (19.48). Mean total temporal lobe volume for male and female were 169.23 cm³ (19.40) and 153.63 cm³ (16.54) respectively. Mean temporal lobe volume for the right side is ranging from 79.18 cm³ (8.25) to 87.25 cm³ (11.11) and for the left side is from 76.79 cm³ (9.42) to 84.55 cm³ (11.04). There was significant correlation between volume of hippocampus and volume of temporal lobe (r = 0.475, p < 0.01). Conclusion: These normative data for hippocampus and temporal lobe were useful reference for Malay population. There was significantly larger right hippocampus as compared to left hippocampal volume. There is fairly good association between the temporal lobe and hippocampal volume within normal adult with normal MRI brain

The Human Parahippocampal Region: I. Temporal Pole Cytoarchitectonic and MRI Correlation

The temporal pole (TP) is the rostralmost portion of the human temporal lobe. Characteristically, it is only present in human and nonhuman primates. TP has been implicated in different cognitive functions such as emotion, attention, behavior, and memory, based on functional studies performed in healthy controls and patients with neurodegenerative diseases through its anatomical connections (amygdala, pulvinar, orbitofrontal cortex). TP was originally described as a single uniform area by Brodmann area 38, and von Economo (area TG of von Economo and Koskinas), and little information on its cytoarchitectonics is known in humans. We hypothesize that 1) TP is not a homogenous area and we aim first at fixating the precise extent and limits of temporopolar cortex (TPC) with adjacent fields and 2) its structure can be correlated with structural magnetic resonance images. We describe here the macroscopic characteristics and cytoarchitecture as two subfields, a medial and a lateral area, that constitute TPC also noticeable in 2D and 3D reconstructions. Our findings suggest that the human TP is a heterogeneous region formed exclusively by TPC for about 7 mm of the temporal tip, and that becomes progressively restricted to the medial and ventral sides of the TP. This cortical area presents topographical and structural features in common with nonhuman primates, which suggests an evolutionary development in human species

Automatic morphometry in Alzheimer's disease and mild cognitive impairment.

Accepted versio

Computerized Analysis of Magnetic Resonance Images to Study Cerebral Anatomy in Developing Neonates

The study of cerebral anatomy in developing neonates is of great importance for the understanding of brain development during the early period of life. This dissertation therefore focuses on three challenges in the modelling of cerebral anatomy in neonates during brain development. The methods that have been developed all use Magnetic Resonance Images (MRI) as source data. To facilitate study of vascular development in the neonatal period, a set of image analysis algorithms are developed to automatically extract and model cerebral vessel trees. The whole process consists of cerebral vessel tracking from automatically placed seed points, vessel tree generation, and vasculature registration and matching. These algorithms have been tested on clinical Time-of- Flight (TOF) MR angiographic datasets. To facilitate study of the neonatal cortex a complete cerebral cortex segmentation and reconstruction pipeline has been developed. Segmentation of the neonatal cortex is not effectively done by existing algorithms designed for the adult brain because the contrast between grey and white matter is reversed. This causes pixels containing tissue mixtures to be incorrectly labelled by conventional methods. The neonatal cortical segmentation method that has been developed is based on a novel expectation-maximization (EM) method with explicit correction for mislabelled partial volume voxels. Based on the resulting cortical segmentation, an implicit surface evolution technique is adopted for the reconstruction of the cortex in neonates. The performance of the method is investigated by performing a detailed landmark study. To facilitate study of cortical development, a cortical surface registration algorithm for aligning the cortical surface is developed. The method first inflates extracted cortical surfaces and then performs a non-rigid surface registration using free-form deformations (FFDs) to remove residual alignment. Validation experiments using data labelled by an expert observer demonstrate that the method can capture local changes and follow the growth of specific sulcus

The structural neurobiology of social anxiety disorder : a clinical neuroimaging study

Includes bibliographical referencesWhile a number of studies have explored the functional neuroanatomy of social anxiety disorder (SAD), comparatively few studies have investigated the structural underpinnings in SAD. 18 psychopharmacologically and psychotherapeutically naïve adult patients with a primary Axis I diagnosis of generalized social anxiety disorder and 18 demographically (age, gender and education) matched healthy controls underwent 3T structural magnetic resonance imaging. A manual tracing protocol was specifically developed to compute the volume of the most prominent subcortical gray matter structures implicated in SAD by previous functional research. Cortical thickness was estimated using an automated algorithm and whole brain analyses of white matter structure were performed using FSL's tract - based spatial statistics comparing fractional anisotropy (FA), mean diffusivity (MD) in individuals with SAD. Manual tracing demonstrated that compared to controls, SAD patients showed an enlarged right globus pallidus. Cortical thickness analyses demonstrated significant cortical thinning in the left isthmus of the cingulate gyrus, the left temporal pole, and the left superior temporal gyrus. Analyses of white matter tractographic data demonstrated reduced FA in in the genu, splenium and tapetum of the corpus callosum. Additionally reduced FA was noticed in the fornix and the right cingulum. Reduced FA was also noted in bilateral corticospinal tracts and the right corona radiata. The results demonstrate structural alterations in limbic circuitry as well as involvement of the basal glanglia and their cortical projections and input pathways

Hippocampal subfields at ultra high field MRI: An overview of segmentation and measurement methods

The hippocampus is one of the most interesting and studied brain regions because of its involvement in memory functions and its vulnerability in pathological conditions, such as neurodegenerative processes. In the recent years, the increasing availability of Magnetic Resonance Imaging (MRI) scanners that operate at ultra-high field (UHF), that is, with static magnetic field strength ≥7T, has opened new research perspectives. Compared to conventional high-field scanners, these systems can provide new contrasts, increased signal-to-noise ratio and higher spatial resolution, thus they may improve the visualization of very small structures of the brain, such as the hippocampal subfields. Studying the morphometry of the hippocampus is crucial in neuroimaging research because changes in volume and thickness of hippocampal subregions may be relevant in the early assessment of pathological cognitive decline and Alzheimer's Disease (AD). The present review provides an overview of the manual, semi-automated and fully automated methods that allow the assessment of hippocampal subfield morphometry at UHF MRI, focusing on the different hippocampal segmentation produced. © 2017 Wiley Periodicals, Inc

Magnetic resonance spectroscopy and brain volumetry in mild cognitive impairment. A prospective study

Objective To assess the accuracy of magnetic resonance spectroscopy (1H-MRS) and brain volumetry in mild cognitive impairment (MCI) to predict conversion to probable Alzheimer''s disease (AD). Methods Forty-eight patients fulfilling the criteria of amnestic MCI who underwent a conventional magnetic resonance imaging (MRI) followed by MRS, and T1-3D on 1.5 Tesla MR unit. At baseline the patients underwent neuropsychological examination. 1H-MRS of the brain was carried out by exploring the left medial occipital lobe and ventral posterior cingulated cortex (vPCC) using the LCModel software. A high resolution T1-3D sequence was acquired to carry out the volumetric measurement. A cortical and subcortical parcellation strategy was used to obtain the volumes of each area within the brain. The patients were followed up to detect conversion to probable AD. Results After a 3-year follow-up, 15 (31.2%) patients converted to AD. The myo-inositol in the occipital cortex and glutamate + glutamine (Glx) in the posterior cingulate cortex predicted conversion to probable AD at 46.1% sensitivity and 90.6% specificity. The positive predictive value was 66.7%, and the negative predictive value was 80.6%, with an overall cross-validated classification accuracy of 77.8%. The volume of the third ventricle, the total white matter and entorhinal cortex predict conversion to probable AD at 46.7% sensitivity and 90.9% specificity. The positive predictive value was 70%, and the negative predictive value was 78.9%, with an overall cross-validated classification accuracy of 77.1%. Combining volumetric measures in addition to the MRS measures the prediction to probable AD has a 38.5% sensitivity and 87.5% specificity, with a positive predictive value of 55.6%, a negative predictive value of 77.8% and an overall accuracy of 73.3%. Conclusion Either MRS or brain volumetric measures are markers separately of cognitive decline and may serve as a noninvasive tool to monitor cognitive changes and progression to dementia in patients with amnestic MCI, but the results do not support the routine use in the clinical settings

Mammillary Body Atrophy in Temporal Lobe Epilepsy With Hippocampal Sclerosis

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