Super Resolution of MR Brain Images Using Compressive Sensing and Fuzzy Logical Rules

Abstract The proficiency of image processing is of extreme importance in perceiving and collecting information from the images, which includes the process of changing or interpreting existing images. In medical image processing, imaging with more accuracy plays a crucial role in better diagnosis or for the posterior analysis of treatment. Magnetic Resonance Imaging (MRI) is a medicinal creative tool for studying the internal structures and functionalities of human brain, knee, heart, liver, etc. Typical MR scans are essential now for better diagnosis but, limited resolution that is often inadequate for extracting detailed and reliable information. So, for the super resolution (SR) of MR brain images concepts of compressive sensing (CS) & fuzzy logical rules to improve data quality are proposed in this paper. Usually, reconstruction of an SR image is the formation of high resolution (HR) image which is obtained from one or few low resolution (LR) images. In the proposed method, with the help of compressive sensing a very limited number of images are considered even though it's a challenging task and fuzzy logical rules for a specific membership function are applied to improve the resolution of the image. To assess the performance of the proposal, different metrics are evaluated and achieved better results.

Analysis of performance test results of 141 CT scaners in Beijing / 中华放射医学与防护杂志

Objective To analyze the performance differences of CT scanners with different detector rows between different manufacturers,and to provide the basis for the rational allocation and use of these CT scanners.Methods According to the result from the sentinel surveillance in 2014,a total of 148 medical institutions were equipped with CT scanners in 16 districts of Beijing,including general hospital(53),cancer hospital(5),TCM hospitals(25),children′s hospitals(2),community hospitals(30)and other specialized medical institutions(33).According to the principle of simple random sampling,40 medical institutions are selected,including 14 general hospitals,1 cancer hospital,7 Chinese medicine hospitals,1 children′s hospital,8 community hospitals and 9 other specialized medical institutions.A total of 141 CT scanners are selected from all CT sets of the selected medical institutions from 2012 to 2014.According to GB 17589-2011 X-ray computed tomography device quality assurance testing status test,four parameters related closely to image quality were tested,including CT value(water),noise,high contrast resolution,and low contrast detectability.Results No significant differences were found in CT value(water),noise and low contrast detectability among CT scanners produced by different manufacturers(P＞0.05),whereas high contrast resolution was found to have a remarkable difference(χ2＝34.706,P＜0.05).Significant differences were found in noise,high contrast resolution and low resolution detectability between the CT scanners with ＜64 detector rows and ≥64 detector rows(χ2＝6.978,10.040,15.973,P＜0.05).However,there is no difference in CT value(water)(P＞0.05).For less-than-64 detector row CT scanners,no significant difference was found in CT value(water),noise and low contrast detectability among different manufacturers(P＞0.05).only high contrast resolution differed remarkably(χ2＝9.941,P＜0.05).For more-than-or equal-to-64 detector row CT scanners,CT value(water)and noise have no differences among different manufacturers(P ＞0.05),whereas,there were significant difference in high contrast resolution and low contrast detectability(χ2＝31.376,32.967,P＜0.05).Conclusions There were a few differences in the performance testing of CT scanners from different manufacturers,and the less-than-64 detector row CT scanners have advantages in noise and low contrast detectability compared with the more-than-64 detector row CT scanners,whereas the latter have advantages in high contrast resolution and scanning time,allowing its wider application in medical institutions with more special diseases.

Differences of activated brain areas during brain error-monitoring in schizophrenia patients / 第二军医大学学报

Objective: To study the differences of activated brain areas during brain error monitoring in schizophrenia patients. Methods: The latencies and amplitudes of error related negativity (ERN) were obtained in 16 patients with first episode schizophrenia and 25 normal controls by high-density event related potential (ERP) technique, and the activated areas were analyzed by low resolution electromagnetic tomography (LORETA). Results: The correct response rate was significantly lower in the schizophrenia participant group than in the control group (P<0.01), and the reaction periods of correct responses and incorrect responses were significantly longer in the schizophrenia group than in the control group (P<0.05, P<0.01). The ERN latencies in the schizophrenic patients were significantly longer on Cz and Pz electrodes compared with those in the control subjects (P<0.05) and ERN amplitudes were significantly smaller than those in the controls (P<0.05). The activation of insula, superior temporal gyrus, middle temporal gyrus, and inferior parietal lobule were obviously lower in the schizophrenic participants than in the controls. Conclusion: Some brain area, such as insular, may contribute to the dysfunction of error monitoring in schizophrenia patients.

Dynamic Process of Visual Change Detection in Human Brain:an ERP Study / 中国心理卫生杂志

Objective:To explore the spatio-temporal dynamics of brain mechanisms in visual change detection by 256-channel event-related potential (ERP) and low-resolution electromagnetic tomography (LORETA) analyses.Methods：ERP were recorded in 12 healthy participants during performing an S1-S2 matching task.Visual stimuli defined by color and shape.Each trial consisted of two sequentially presented stimuli (S1 and S2),where S2 was either the same as S1,different from S1 in shape only,different in color only,or different in both color and shape.Subjects matched the stimuli according to task demands：attending to color and attending to shape.Result：Change condition elicited change-related positivity (CRP) ranging 135～165 ms.The estimated source regions contributing to CRP were lingual gyrus and cuneus of occipital lobe.N200 was elicited in no change and task-irrelevant change condition ranging 235～275 ms.The source for N200 was in the right temporal fusiform gyrus,middle temporal gyrus and parahippocampal gyrus.In the time window of 240～320 ms,N270 was elicited in all change conditions.The N270 source was localizable to the anterior cingulated cortex and amygdala.Conclusion：In the early stage,CRP reflects the preattentive processing of visual changes.The LORETA result confirms that CRP is generated in the early visual areas.N200 may be related to the active ignored processing of task-irrelevant change.The source for N200 is in the right temporal fusiform gyrus,middle temporal gyrus and parahippocampal gyrus.In the late stage,N270 reflects the advanced processing of visual change in the human brain.The N270 source may be in anterior cingulate cortex (ACC) and amygdala.

Comparison of Low Resolution Electromagnetic Tomography Imaging Between Subjects With Mild and Severe Obstructive Sleep Apnea Syndrome: A Preliminary Study

OBJECTIVE: The purpose of this study was to identify the regions of the brain associated with recurrent nocturnal chronic hypoxic episodes in patients with untreated obstructive sleep apnea syndrome (OSAS) using low-resolution electromagnetic tomography (LORETA) and quantitative electroencephalography (QEEG). METHODS: Nocturnal polysomnograph (NPSG) and subsequent morning electroencephalograph (EEG) were measured in 20 subjects with OSAS. Mild (n=10 ages 39.5+/-12.1 years) and severe (n=10 ages 41.7+/-13.6 years) right-handed male OSAS subjects were selected by interview and questionnaires including the NPSG, Beck Depression Inventory, Beck Anxiety Inventory, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index. The LORETA and QEEG were compared between the severe and mild OSAS groups by frequency bands (delta 1-3 Hz, theta 4-7 Hz, alpha 8-12 Hz, beta1 13-18 Hz, beta2 19-21 Hz, beta3 22-30 Hz, and total 1-30 Hz) made by spectral analysis during resting with the eyes closed. RESULTS: The LORETA analysis showed decreased alpha activity at the right posterior cingulate gyrus (Brodmann area 23) in cases with severe OSAS compared to mild OSAS (p<0.05). For the QEEG, the absolute power of the alpha activity (8-12 Hz) was decreased in P3 (p=0.047), PZ (p=0.039) and O2 (p=0.04) in cases with severe OSAS compared to mild OSAS cases. The LORETA and QEEG analyses had similar results with regard to band, activation and location. CONCLUSION: The decreased activity of the alpha frequency in the right posterior cingulate gyrus, in patients with severe OSAS compared to those with mild OSAS, suggests that chronic repeated short-term hypoxia during sleep, in OSAS, could provoke cortical brain dysfunction associated with cognitive dysfunction such as memory and attention.

Cortical Representation to Odorant Stimulation: Statistical Non-parametric Mapping of Low Resolution Electro magnetic Tomography (LORETA)

BACKGROUND: Although olfactory stimulation has been known to produce effects on human mood and cognition, the specific EEG patterns of activity was reported diversely. The purpose of this study was to investigate EEG changes by odorant using low resolution electromagnetic tomography (LORETA) in young healthy subjects. METHODS: The EEG's of nineteen (10 males, 9 females) non-smoking right-handed college students were recorded after odorant stimulation. A nineteen-channel EEG was recorded referenced to linked ears before and during olfactory stimulation. Olfactory stimulation was presented with lavender essential oil by blotter method. The LORETA power was computed from ten 2-s epochs, separately for the different EEG frequencies. The power values were logarithmically transformed and paired sample t-tests were done for each voxel and frequency band (1.5-30 Hz). Statistical results were displayed 3-dimensionally on the standard brain template. RESULTS: All subjects experienced positive feelings (relaxed and pleasant) by olfactory stimulation with lavender oil (p<0.01). The LORETA power of theta and alpha band was increased in the dorsolateral and medial frontal areas, predominantly in the posterior cingulate gyri. The alpha LORETA power was also increased in bilateral orbitofrontal regions and the left perisylvian region including the insular cortex. Beta power was increased in the posterior cingulated gyri and mesial temporal region, predominantly on the left side. CONCLUSIONS: These results suggest that olfaction associated with emotional feeling might induce brain electrical power changes not only in the limbic system but also in the neocortex with lateralization to the dominant hemisphere.