Objective To investigate the value of MR diffusion tensor imaging (DTI) quantitative parameters in evaluating the injury of the tibial nerve and the common peroneal nerve in patients with Guillain-Barre syndrome(GBS). Methods Sixteen healthy volunteers and sixteen patients with GBS underwent DTI examination of the tibial nerve and the common peroneal nerve. The denervation of skeletal muscles controlled by the tibial nerve and the common peroneal nerve was observed. The apparent diffusion coefficient (ADC) value, fractional anisotropy (FA) value, axial diffusivity (AD) value and radial diffusivity (RD) value were measured respectively,and diffusion tensor tractography (DTT) of the tibial nerve and the common peroneal nerve was performed. Between-groups comparison was made with the independent sample t test and receiver-operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy of the parameters. Results (1)The MR features of denervated skeletal muscles comprehend hyperintensity on T2WI SPAIR sequence and the instinct boundary, muscle atrophy occationally. (2)Compared with the healthy volunteer group, the ADC value of the tibial nerve and the common peroneal nerve of GBS group was increased and the FA value, AD value, RD value were decreased, and there was significant difference between the ADC value, FA value, AD value and RD value of GBS and volunteer groups respectively(P<0.05). The area under the curve (AUC) of FA value was higher than that of the corresponding ADC value in the tibial nerve and the common peroneal nerve. (3)DTT showed that the number of fibers decreased in patients with GBS compared to the normal volunteers. Conclusion MR can clearly show the denervated skeletal muscles controlled by the tibial nerve and the common peroneal nerve. The ADC value, FA value, AD value and RD value, the quantitative parameters of DTI, can evaluate the injury of the tibial nerve and the common peroneal nerve in patients with GBS.

BACKGROUNDColonization with methicillin-resistant Staphylococcus aureus (MRSA) is a risk factor for subsequent invasive MRSA infection, particularly in patients admitted for critical care. The purpose of this study was to investigate the risk factors affecting nasal colonization of MRSA in patients admitted to intensive care units (ICU).

METHODSBetween August 1, 2011 and June 30, 2012, we screened for MRSA nasal colonization in 350 patients by Real-time PCR within 24 hours of admission by means of swab samples taken from the anterior nares. According to the results of PCR, the patients were divided into 2 groups: the positive group with nasal MRSA colonization and the negative group without nasal MRSA colonization. The 31 (8.86%) patients were MRSA positive. The risk factors evaluated included thirteen variables, which were analyzed by t test for continuous variables and χ(2) test for discrete variables. The variables with significance (P < 0.05) were analyzed with stepwise Logistic regression.

RESULTSThere were differences (P < 0.05) in four variables between two groups. The duration of stay in hospital prior to ICU admission in the positive group was (35.7 ± 16.1) days, vs. (4.5 ± 3.1) days in the negative group. The average blood albumin level was (28.4 ± 2.9) g/L in the positive group, vs. (30.5 ± 4.3) g/L in the negative group. Of 31 patients in the positive group, seven had been treated with antibiotics longer than seven days vs. 34 of 319 patients in the negative group. In the positive group, four of 31 patients received treatment with more than two classes of antibiotics prior to admission in ICU, contrasted to 13 of 319 patients in the negative group. Furthermore, stepwise Logistic regression analysis for these four variables indicates that the duration of stay in hospital prior to ICU admission may be an independent risk factor.

CONCLUSIONSMRSA colonization in ICU admission may be related to many factors. The duration of stay in hospital prior to ICU admission is an independent risk factor.

Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents ; therapeutic use ; Female ; Humans ; Intensive Care Units ; Male ; Methicillin-Resistant Staphylococcus aureus ; pathogenicity ; Middle Aged ; Nasal Cavity ; microbiology ; Polymerase Chain Reaction ; Risk Factors ; Staphylococcal Infections ; drug therapy ; Young Adult