Objective To evaluate the capability of Turbo inversion recovery magnitude (TIRM) magnetic resonance neurography (MRN) in the diagnosie of sacral plexus injury by comparing MRN findings with surgical results.Methods Ten patients with sacral plexus injury confirmed surgically underwent conventional T1WI,T2WI,TIRM and coronal TIRM MRN before operations from June,2011 to December,2012.The MRI data and surgical data were analyzed retrospectively to observe nerve injury.Results The coronal TIRM MRN images displayed 93 trunks of sacral plexus,of which 37 were confirmed injury by operation.The MRI findings were as follows:6 trunks involved continuous nerves,but with thickening and blurred margin,as well as abnormal high signal intensity;22 trunks were continuous,but with distortion,stiffness and adhesion accompanied by heterogeneous signal intensity and structural disorder;3 trunks showed complete loss of continuity,absence of normal signal,accompanied by retraction;and 3 trunks involved formation of traumatic neurofibroma.The coincidence of injured nerve trunks diagnosed by MRN with surgical findings amounts to 81.08％ (30/37).Conclusion MR with coronal TIRM imaging is effective in the diagnosis and depiction of sacral plexus injury,therefore it can be used as conventional sequence in sacral plexus examination to detect sacral plexus avulsion.

Objective To explore the mechanism of self-awareness in the heavy smokers(HS)by using regional homogeneity(ReHo)combined with resting-state functional MRI(fMRI).Methods Thirty HS and 31 healthy non-smokers(NS)matched for age and sex underwent a 3.0 T resting-state fMRI.The data were post-processed by SPM 5 and then the ReHo values were calculated by REST software.The ReHo values between the two groups were compared by two-sample t-test.The brain map with significant difference of ReHo value was obtained.Results Compared with that in NS group,the regions with decreased ReHo value included the bilateral precuneus,superior frontal gyrus,medial prefrontal cortex,right angular gyrus,inferior frontal gyrus,inferior occipital gyrus,cerebellum,and left middle frontal gyrus in HS group.The regions of increased ReHo value included the bilateral insula,parahippocampal gyrus,white matter of parietal lobe,pons,left inferior parietal lobule,lingual gyrus,thalamus,inferior orbital gyrus,white matter of temporal-frontal lobe,and cerebellum.The difference was more obvious in the left hemisphere.Conclusions In HS,abnormal ReHo on a resting state which reflects network of smoking addiction.This method may be helpful in understanding the mechanism of self-awareness in HS.