An MRI denoising method using image data redundancy and local SNR estimation.

This paper presents an LMMSE-based method for the three-dimensional (3D) denoising of MR images assuming a Rician noise model. Conventionally, the LMMSE method estimates the noise-less signal values using the observed MR data samples within local neighborhoods. This is not an efficient procedure to deal with this issue while the 3D MR data intrinsically includes many similar samples that can be used to improve the estimation results. To overcome this problem, we model MR data as random fields and establish a principled way which is capable of choosing the samples not only from a local neighborhood but also from a large portion of the given data. To follow the similar samples within the MR data, an effective similarity measure based on the local statistical moments of images is presented. The parameters of the proposed filter are automatically chosen from the estimated local signal-to-noise ratio. To further enhance the denoising performance, a recursive version of the introduced approach is also addressed. The proposed filter is compared with related state-of-the-art filters using both synthetic and real MR datasets. The experimental results demonstrate the superior performance of our proposal in removing the noise and preserving the anatomical structures of MR images.

Association of persistent hyperglycemia with outcome of severe traumatic brain injury in pediatric population.

PURPOSE: Hyperglycemia is a common secondary insult associated with an increased risk of mortality and poor outcome in traumatic brain injury (TBI), but the effect of hyperglycemia on outcomes of severe TBI in children and adolescents is less apparent. The aim of this study was to evaluate the association of hyperglycemia with mortality in pediatric patients with severe TBI. METHODS: In this cross-sectional study, data of all children and adolescents with severe TBI admitted to Poursina Hospital in Rasht, including age, gender, Glasgow Coma Scale (GCS) upon admission, mortality rate, hospital length of stay, and serial blood glucose during the first three consecutive ICU days following admission, were reviewed from April 2007 to May 2011. After univariate analysis and adjustment for related covariates, logistic regression model was established to determine the association between persistent hyperglycemia and outcome. RESULTS: One-hundred and twenty-two children were included with a median admission GCS of 6 (interquartile range (IQR) 5-7) and a median age of 13 years (IQR 7.75-17). Among them, 91 were boys (74.6%) and 31 were girls (26.6%); the overall mortality was 40.2% (n=49). Patients who died had a significantly greater blood glucose levels than survivors for the first 3 days of admission (P=0.003, P<0.001, P=0.001, respectively). Moreover, persistent hyperglycemia during the first 3 days of admission had an adjusted odds ratio of 11.11 for mortality (P<0.001). CONCLUSION: Early hyperglycemia is associated with poor outcome, and persistent hyperglycemia is a powerful and independent predictor of mortality in children and adolescents with severe TBI.

Effects of neurosurgical treatment and severity of head injury on cognitive functioning, general health and incidence of mental disorders in patients with traumatic brain injury.

BACKGROUND: Neurosurgical treatment and the severity of head injury (HI) can have remarkable effect on patients' neuropsychiatric outcomes. OBJECTIVES: This research aimed to study the effect of these factors on cognitive functioning, general health and incidence of mental disorders in patients with a traumatic brain injury (TBI). PATIENTS AND METHODS: In this descriptive, longitudinal study, 206 TBI patients entered the study by consecutive sampling; they were then compared according to neurosurgery status and severity of their HI. Both groups underwent neurosurgical and psychological examinations. The mini mental state examination (MMSE) and general health questionnaire-28 items (GHQ-28) were administered to the study participants. At follow-up, four months later, the groups underwent a structured clinical interview by a psychiatrist based on the diagnostic and statistical manual of mental disorders, fourth edition (DSM-IV) diagnostic criteria regarding the presence of mental disorders. RESULTS: Analysis of covariance (ANCOVA) and multivariate analysis of covariance (MANCOVA) were performed and adjusted for the effect of confounding variables (age, gender, Glasgow outcome scale (GOS) , and level of education). The severity of HI had the most significant effect for the following variables; cognitive functioning and physical symptoms (P < 0.05). The effect of the neurosurgical treatment factor was not significant; however, the interaction effect of the two variables on social dysfunction, and total score of the GHQ-28 questionnaire appeared to be significant (P < 0.05). Fisher's exact test indicated that after a four month follow-up period, no significant differences were seen between the two groups (with or without neurosurgery) in the incidence of mental disorders, while χ(2) Test showed that having a more severe HI is significantly correlated with the incidence of mental disorders (P < 0.01). CONCLUSIONS: The implications of this study should be discussed with an emphasis on negative, effective factors on the cognitive - behavioral and neuropsychiatric outcomes of a TBI.