Functional magnetic resonance imaging(fMRI) has been widely applied in many fields,such as neurology,psychology,etc.Recently it has also been used to study the visceral hypersensitivity of the gut.This review gives an overview of the basic principle of fMRI and its application in the visceral sensitivity of esophagus and rectum.

Objective To explore the application of diffusion tensor imaging in the assessment of ischemic muscle in hind-limb ischemia model of rabbit. Methods Excision of femoral artery in unilateral hind limb was done in 14 New Zealand white rabbits and ischemic model were established in 12 rabbits. Three (12 rabbits),10(10 rabbits) ,28(7 rabbits),56(5 rabbits) days after the model establishment, DTI scan was performed on bilateral hind limbs in each of the models, respectively and, λ_1,λ_2,λ_3, ADC and FA values were measured. Histological analysis was also performed at these time points. Pared t test was used to compare the differences of these indexes in bilateral hind limbs. Results Following femoral artery excision, a rapid ascending of ADC,λ_2,λ_3 values with sharply reduced FA value was observed in ligated hind-limb, which reached maximal on 3 days post-excision (ADC_(ligated)= 1.72±0.16, ADC_(unligated)= 1.53±0.16, t = 6.48, P < 0.01 ; λ_(2 ligated)= 1.70±0.15, λ_(2 unligated)= 1.51±0.06, t=10.87, P < 0.01 ; λ_(3 ligated_ =1.17±0.12, λ_(3 unligated)= 0.88±0.12, t=6.67, P < 0.01 ; FA_(ligated)= 0.24±0.04, FA_(unligated) =0.39±0.03, t = -10.61 ,P <0.01) and histologic analysis revealed the severest muscle damag at that time. Ischemic muscle recovered very slowly during the first 10 day post-excision accompanied with reduction of ADC , λ_2, λ_3 values, however there was also difference of ADC,λ_2, λ_3 values between ligated and nonligated limbs except λ_1 ( ADC_(ligated) = 1.65±0. 16, ADC_(unligated)= 1.50±0.12, t =6.42, P <0.01 ; λ_(2 ligated) = 1.62±0.32, λ_(2 unligated) =1.48±0.31, t=5.09, P < 0.01) ; λ_(3 ligated)= 1.11±0.13, λ_(3 unligated)= 0.85±0.09, t=6.26, P <0. 01;λ_(1 ligated)=2.20±0.21, λ_(1 unligated) =2.18+0.20, t=0.87, P=0.40). After 28 days, ADC and λ_3 returned to normal (ADC_(ligated)= 1.51±0. 16, ADC_(unligated)= 1.55±0.14, t=-1.35, P=0.23 ; λ_(3 ligated) =0.95±0. 10, λ_(3 unligated)= 0.92±0.06, t=1.70, P=0.14), but λ_2 and FA of ligated limb were still different from those of nonligated limb (λ_(2 ligated)= 1.45±0.23, λ_(2 unligated)= 1.52±0. 95, t=-3.56, P=0.012; FA_(ligated)=0.35±0.02, FA_(unligated)=0.40±0.03, t=-3.83, P<0.01). After 56 days, all parameters retuned to normal(ADC_(ligated) =1.57±0.18, ADC_(unligated)=1.58±0.23, t=-0.71, P=0.52; λ_(1 ligated) =2.18±0.18, λ_(1 unligated)=2.24±0.14, t=-0.22, P=0.10; λ_(2 ligated)=1.64±0.13, λ_(2 unligated)=1.59±0.15, t=0.89, P=0.42; λ_(3 ligated)=0.89±0.1,λ_(3 unligated)=0.91±0.07, t=- 1.64,P= 0.18; FA_(ligated)= 0.39±0. 03, FA_(unligated)= 0.41±0.02, t=-0.83, P=0.47). Conclusion DTI is a quantitative and relatively accurate technique to assess time-dependent changes of ischemic muscle in hindlimb ischemia model of rabbit.

Objective To explore the relation between the enlargement of orbital volume and the degree of enophthalmos, and that between the enlarged volume of floor together with that of medial wall and the degree of enophthalmos. Methods A total of 17 patients of unilarteral orbital fracture were scanned by MSCT (slice width 0.625mm), who suffered late enophthalmos as a results of combination fracture of the medial wall and floor. The clinical data were collected, and input into a software named MIMICS in order to measure orbital volume, the degree of enophthalmos, the enlarged volume of medial wall, and that of orbital floor. Simple linear correlation and regression were carried out between the enlargement of orbital volume and the degree of enophthalmos. Mutiple linear correlation and regression were carried out between the enlarging volume of floor together with that of medial wall and the degree of enophthalmos. Results The equation of the enlargement of orbital volume (V) and the degree of enophthalmos (E) was E= 0.851 V-0.197 (Pearson r=0.969, P＜0.01, the 95% confidence intervals of 0.732-0.970). The standardized equation between the enlarged volume of floor together with that of medial wall and the degree of enophthalmos was E= 0.690 VF+0.413 VM-0. 086 (setpwise, entry =0.5, removal= 0. 11,P＜0.01 ); Comparing the standardized coefficients of independent variables, the outcome was bF (0.690) ＞ bM(0.413). Conclusion Significant linear correlation between the increment of the orbital volume and the degree of enophthalmos is found that 1.0 ml enlargeement in bony volume causes approximately 0.9 mm of enophthalmos; enlarged volume of floor has more powerful influence on the degree of enophthalmos than enlarged volume of medial wall, the former is 1.56 times of the latter.

Purpose Early diagnosis of Alzheimer's disease is lack of objective imaging marker.This study evaluates characteristics of cerebral blood flow (CBF) and gray matter atrophy in patients with mild Alzheimer's disease (AD) by using 3D arterial spin labeling (3D ASL) and thin slice 3D T1 weighted images of voxel-based method (VBM).Materials and Methods Sixteen mild AD patients (mild AD group) and sixteen normal control subjects (control group) were recruited.3D ASL and T1WI SPGR sequences were performed.By using voxel-based method,the whole brain CBF and T1WI images were analyzed.CBF and volume of gray matter were compared between two groups,and correlation analysis was done.Results Compared with control group,CBF hypoperfusion was detected in bilateral precuneus,cunei,middle temporal cortex,superior temporalcortex,left parahippocampal gyrus,left superior temporal pole and right superioroccipital gyrus in mild AD group (t=3.84,Pcorrected＜0.05).Compared with control group,gray matter atrophy was found in bilateral hippocampi,amygdalae,superior temporal pole,left parahippocampal gyrus,left inferior temporal cortex in mild AD group (t=4.12,Pcorrected＜0.05).There was a correlation in left parahippocampal gyrus and left upper pole of the temporal between changes of CBF and volume of gray matter in mild AD patients (r=0.50,P＜0.05).Conclusion Voxel-based VBM and ASL can evaluate AD patients' cerebral atrophy and CBF change in early stage,and there is a correlation between changes of CBF and gray matter atrophy in some overlap areas.

Objectives To evaluate the prognostic value of the coronary artery calcium (CAC) score in patients with stable angina pectoris (SAP) who underwent percutaneous coronary intervention (PCI). Methods A total of 334 consecutive patients with SAP who underwent first PCI following multi-slice computer tomography (MSCT) were enrolled from our institution between January 2007 and June 2012. The CAC score was calculated according to the standard Agatston calcium scoring algorithm. Complex PCI was defined as use of high pressure bal-loon, kissing balloon and/or rotablator. Procedure-related complications included dissection, occlusion, perforation, no/slow flow and emer-gency coronary artery bypass grafting. Main adverse cardiac events (MACE) were defined as a combined end point of death, non-fatal myo-cardial infarction, target lesion revascularization and rehospitalization for cardiac ischemic events. Results Patients with a CAC score>300 (n=145) had significantly higher PCI complexity (13.1%vs. 5.8%, P=0.017) and rate of procedure-related complications (17.2%vs. 7.4%, P=0.005) than patients with a CAC score≤300 (n=189). After a median follow-up of 22.5 months (4-72 months), patients with a CAC score≤300 differ greatly than those patients with CAC score>300 in cumulative non-events survival rates (88.9 vs. 79.0%, Log rank 4.577, P=0.032). After adjusted for other factors, the risk of MACE was significantly higher [hazard ratio (HR):4.3, 95%confidence inter-val (95%CI):2.4-8.2, P=0.038] in patients with a CAC score>300 compared to patients with a lower CAC score. Conclusions The CAC score is an independent predictor for MACE in SAP patients who underwent PCI and indicates complexity of PCI and proce-dure-related complications.