| Objective1. To explore the optimal 3.0T MR Volume Scan Parameter of Nucleus Accumbens.2. To search for the best way in displaying nucleus accumbens by means of 3.0T MRI scanner.3. To measure the volume of nucleus accumbens by means of 3.0T MR scanner and analyze the difference between two sides and between males and females.4. To investigate the differences between heroin addicts and normal controls in the default mode functional connectivity in the resting-state brain.Methods1. 72 healthy volunteers ,divided into 12 groups,undertook MR scan using 3D fast spoiled gradient recall (3D-FSPGR)sequence.With the other parameters fixed,4 different preparation time and 3 matrix were combined respectively contributing to 12 protocols.Contrast-noise ratio (CNR) of nucleus accumbens and nearby white matter was measured and analyzed.2. 32 healthy volunteers underwent the routine and volume MR imaging examination of brain and then the volume images were reconstructed and classified into 12 groups based on the different reconstructing angles. The reconstructed images of each group were scored according to the degrees of whether the nucleus accumbens was completely displayed or not.3. 42 healthy volunteers(24males and 18femals),ranging from 18 years to 55 years ,medial age 25 years old, underwent the routine and volume MR imaging examination of the brain. The volume of nucleus accumbens on both sides was measured and the difference between both sides and different gender was analyzed.4. 28 volunteers participated this study ,14 of whom were heroin addicts and 14 of whom were healthy adults.The two groups were matched in age,gender,weight,right handedness and education.Both groups undertook MR scanning and the data was acquired and processed.The ventrolateral anterior cingulate cortex was defined as the region of interest(ROI) based on which the functional connectivity map of the whole brain was built and compared.Results1. Of all the groups ,the CNR of the first group was the best(P<0.05).When the matrix was 256×256, the CNR of the first group was the best(P<0.05).When the matrix was 342×342, no significant statistical difference was found among the fifth to the eighth group(P>0.05). When the matrix was 512×512, the CNR of the ninth group was the best(P<0.05).2. Between male and female, the display of nucleus accumbens had no statistical significance, but it did have between the group with the reconstructing angle 900 and other groups.3. Among males ,females or total volunteers the average volume of nucleus accumbens on the right side is significantly larger than it is on the left (P<0.001).No significant difference of the total volume between males and females was found(P>0.05).4. The vACC showed more significant resting-state connectivity with the following regions in the heroin addicts group than in the normal group: insula bilaterally,left hippocampus, right parahippocampal gyrus, lingual gyrus bilaterally,inferior frontal gyrus bilaterally and superior temporal gyrus bilaterally.And it showed more significant resting-state connectivity with the following regions in the normal group than in the heroin addicts group:PCC, left DLPFC, precuneus bilaterally,cerebellum bilaterally,subcallosal gyrus bilaterally and right nucleus accumbens.(P<0.01)Conclusions1. To acquire excellent images of nucleus accumbens by means of 3D-FSPGR with 3.0T MR scanner, the proper matrix and preparation time should be 342×342, 350-500ms when the other parameters is TR=8.1ms /TE=3.6ms /FOV=24cm×19.6cm /slice thickness=1.4mm /spacing=-0.7mm /flip angle=20°/NEX=2.2. 3.0T MRI can display nucleus accumbens effectively and excellently. The best method to show the nucleus accumbens is the coronal scan, its plane should be vertical to the line between anterior-posterior commissure.3. Among healthy adults,the volume of nucleus accumbens on the right side is larger than it is on the left. There is no significant difference of total volume of nucleus accumbens between males and females.4. Significant difference exists between heroin addicts and healthy adults in functional connectivity maps based on vACC in the resting-state brain.The method of resting-state brain fMRI study shed light on the study of addiction mechanism. |
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