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ABSTRACT: A method has been developed to establish the crystal position look-up table for positron emission tomography with block detectors.
It is based on the principle that the counts in crystal position histogram obey the Gaussian mixture model (GMM). This method
has taken full consideration of the characteristics of the GMM and the detector itself. The experimental results have proved
that it is simple, reliable, and universal.
Science in China Series E Technological Sciences 04/2012; 52(8):2418-2423. · 1.02 Impact Factor
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ABSTRACT: To automatically extract regions of interest (ROIs) and simultaneously preserve the anatomical characteristics of each individual, we developed a new atlas-based method utilizing a pair of coregistered brain template and digital atlas.
Unlike the previous atlas-based method, this method treats each individual as the target image, and the template and atlas are each transformed to register with the individual. To evaluate the accuracy of this method we implemented it in extracting the hippocampus from two groups of T(2)-weighted structural images with different spatial resolutions and a group of T(2)*-weighted functional images. Furthermore, the results were compared against a manually segmented hippocampus and an atlas-derived hippocampus.
Jaccard similarity (JS) reached 84.7%-90.5%, and relative error in volume (RV) was 4.8%-12.7%. The consistency observed between the results of the proposed method and manual drawing was therefore considerable.
We developed a new atlas-based method for ROI extraction that can automatically extract ROI and simultaneously preserve each individual's unique anatomical characteristics.
Journal of Magnetic Resonance Imaging 10/2010; 32(4):830-5. · 2.70 Impact Factor
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ABSTRACT: Structural brain abnormalities have been widely reported in major depressive disorder (MDD). However, many previous results cannot exclude the interferences of medication or multiple recurrent episodes. In this study, we examined structural brain abnormalities by comparing 68 drug-naïve first-episode adult-onset MDD and 68 healthy controls (HCs). Structural magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) methods were used. The mean values of grey matter volume/white matter volume (GMV/WMV) were calculated, then the differences between MDD and HCs were analyzed, and the associations of the differences with clinical characteristics of depression were discussed. The whole brain GMV/WMV did not differ between MDD patients and HCs; however, the regional GMV of the right pre-supplementary motor area (pre-SMA) was smaller in MDD patients. The GMV of both hippocampi was positively correlated with symptom severity and lower in patients with long durations. These results indicate the GMV reduction of the pre-SMA at an early stage of depression, whereas the GMV of the hippocampus is associated with depressive characteristics. Moreover, the whole brain GMV/WMV was negatively related to the duration of depression, supporting that volume loss could become progressive during the development of disease. These results may suggest the importance of identifying and intervening depression at an early stage, especially the first year after onset, to prevent volume loss in the brain.
Neuroscience Letters 08/2010; 480(1):30-4. · 2.11 Impact Factor
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Jian Xu,
Yuqi Cheng, Pei Chai,
Zhaoping Lu,
Haijun Li,
Chunrong Luo,
Xizhi Li,
Lin Li,
Qixin Zhou,
Bing Chen,
Jun Cao,
Xiufeng Xu,
Baoci Shan,
Lin Xu,
Jianfan Wen
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ABSTRACT: The central nervous system (CNS) is often affected by systemic lupus erythematosus (SLE), but assessment of CNS outcomes using noninvasive cerebral structural measures remains in its infancy. Magnetic resonance imaging (MRI) with expert visual interpretation is critical to diagnosis, but does not permit quantitative measurements. Our pilot study investigated whether quantitative brain volumetric analyses could be used to detect white-matter (WM) abnormalities and responses to treatment in SLE (ClinicalTrials.gov: NCT00703742).
Forty-two pairs of SLE patients and healthy controls underwent high-resolution 3-dimensional structural MRI scans. Combining voxel-based morphometry and region of interest analyses, subtle WM volume abnormalities in whole brains from SLE patients were identified, and regional WM volume was calculated. Associations between WM volume and symptom severity, as well as the effects of immunosuppressive therapy, were then investigated.
The WM volume of the SLE group was significantly decreased in the bilateral posterior and anterior crus of the internal capsule (PIC and AIC, respectively), the subgyral right frontal lobe, and left temporal lobe (p < 0.001). Regional WM volume (left PIC and right AIC) was correlated with SLEDAI scores. The WM volume of patients treated with immunosuppressive therapy was greater than that of patients who were never treated with immunosuppressive therapy.
Quantitative brain volumetric analyses detect brain injuries in WM for SLE that are not obvious by conventional MRI, and may be adequately sensitive and quantitative to measure the effect of therapeutic interventions in preventing brain injury and outcomes in SLE.
The Journal of Rheumatology 03/2010; 37(5):974-86. · 3.69 Impact Factor
