| BackgroundThe decussation of superior cerebellar peduncle (DSCP) is located in midline, in front of midbrain aqueduct, which is crossed by bilateral superior cerebellar peduncles at the level of the inferior midbrain. The superior cerebellar peduncle (SCP) is usually affected by many diseases, such as Friedreich’s ataxia, Parkinson’s disease, schizophrenia, progressive supranuclear palsy, Joubert syndrome, multiple sclerosis, and cerebral infarction, at al. These diseases could be involved the DSCP. On conventional MRI, DSCP usually shows low signal intensity (SI) on midsagittal T1WI, low signal intensity (SI) on proton density-weighted imaging (PDWI) in neurologically normal brain. However, the signal changes are not displayed on T2WI. On diffusion-weighted imaging (DWI), hyperintense of DSCP is showed a symmetrical inverted triangle on DWIslice, two symmetrical semi-circular on DWIphase and no hyperintense on DWIread. On diffusion tensor imaging (DTI), DSCP demonstrates a red spot on axial color fractional anisotropy (FA) map image. There are five kinds of fiber tracking appearances at the level of DSCP on DTT. The fiber crossed to the opposited red nucleus in anterior-posterior style, superior-inferior style and single main bundle fiber, kissing fiber and missing fiber sign. However, the SI change of DSCP with age and gender is not identified on SE-T1WI, DWI and apparent diffusion coefficient (ADC) map.Part one:Signal intensity of the decussation of superior cerebellar peduncle on T1WI:correlation with age and genderPurpose:This study is to evaluate the signal characteristics of the DSCP on spin-echo (SE) T1WI of different planes and investigate relationship between SI of the DSCP and age and gender on SE-T1WI in healthy subjects.Materials and Methods:Firstly, sagittal, axial and coronal SE T1-weighted images (TR/TE,450/11;3signals averaged; matrix,512×512; section thickness,4mm; no intersection gap, and FOV,190mm) of the brain were acquired in20healthy volunteers (10men and10women; mean age,36.2years; age range,24-44years) at1.5T, respectively. The signal characteristics of DSCP on TlWI with different planes were evaluated consensually by two neuroradiologists. The signal of DSCP was divided into low signal, isointense and high signal. The optimal plane to display the DSCP on T1WI was analysed. Secondly, midsagittal SE-T1WI (TR/TE,450/11;3signals averaged; matrix,512×512; section thickness,4mm; no intersection gap, and FOV,190mm) of120neurologically normal subjects (52men,68women; age range:4-64years, mean age:31years) were evaluated retrospectively. Assessment of the Sls was done by one radiologist and by placing circular ROIs in the DSCP, superior midbrain, and the background of images. Background signal was measured in the pontine basement on the same image. Noise was defined as the standard deviation (SD) of the SI within a ROI outside the head (i.e., air). Contrast-to-noisc ratios (CNR) of the DSCP and the superior midbrain were calculated. Two-paired samples t-test was used to evaluate the SI difference between DSCP and superior midbrain. One-way analysis of variance (ANOVA) and bivariate correlation analysis were performed to evaluate the effects of gender and age.Results: In20healthy adults, the DSCP was either isointense (one objective,5%) or hypointense (19subjects,95%) on sagittal T1WI, either isointense (eight subjects,40%) or hypointcnse (12subjects,60%) on both axial and coronal T1WI. No DSCP manifested a high SI appearance on T1WI. Sagittal plane is much better than the axial and coronal planes in displaying the DSCP on SE-T1WI (x2=5.161, P=0.023). In120healthy patients, twenty percent of DSCP were isointense (24/120),80%of them were hypointcnse (96/120), compared to the superior midbrain. In contrast, a hyperintense appearance was not seen at all in any of age groups. For quantitative interpretation, the CNR was significantly lower in the DSCP (-3.021±1.471) than in the superior midbrain (2.130±1.506,t=-30.078,P=0.000). The CNRs tended to be lower in females than in males (-3.176±1.450vs-2.818±1.488); however, this difference was not significant (t=-1.325,t’=0.118). Multiple comparisons showed no significantly differences with respect to age groups (F=0.974,P=0.437). The CNR of DSCP was not correlate with age (r=0.028,P=0.764) by bivariate correlation.Conclusion: Sagittal plane is the best one to display the DSCP on SE-T1WI, compared to the axial and coronal planes. The SI of DSCP is usually lower than that of superior midbrain on midsagittal Tl WI which shows no correlation with gender or age in healthy subjects. This finding is helpful for the further understanding of the pathological changes of midbrains. Part two:Signal intensity of the decussation of superior cerebellar peduncle on axial DWI:correlation with age and genderPurpose:This study is to evaluate the signal characteristics of the DSCP on axial DWI and investigate relationship between diffusion-weighted SI and ADC value of the DSCP and age and gender in healthy adults.Materials and Methods:Brain axial diffusion-weighted images (spin-echo planar imaging sequence, TR/TE,3200/94ms; diffusion gradient encoding in three orthogonal directions;6=0,1000s/mm2; matrix,192×192; section thickness,5mm; intersection gap,1.5mm; and FOV,230mm) of145neurologically normal adults (70men,75women; age range:31-79years, mean age:48.7years) were evaluated retrospectively. The signal of DSCP was divided into low signal, isointense and high signal. The signal characteristics of DSCP on axial and sagittal DWI were evaluated consensually by two neuroradiologists. Secondly, Assessment of the SIs was done by one radiologist and by placing circular ROIs in the DSCP, periaqueductal gray (PAG), and the background of images. Background signal was measured in the left temporal lobe white matter on the same image. Noise was defined as the standard deviation (SD) of the SI within a ROI outside the head (i.e., air). Contrast-to-noise ratios (CNR) of the DSCP and the PAG were calculated. Two-paired samples t-test was used to evaluate the SI difference between DSCP and PAG. Difference of age groups was used one-way analysis of variance (ANOVA). and bivariate correlation analysis were performed to evaluate the effects of gender and age. and Pearson correlation coefficient (r) was obtained.Results:In145healthy adults, sixty-five point five percent of DSCP were hyperintense (95/145),34.5%of them were isointense (50/145), compared to the PAG. In contrast, a hypointense appearance was not seen at all in any of age groups. For quantitative interpretation, the CNR was significantly higher in the DSCP (29.53±7.65) than in the PAG (22.54±5.59; t=17.084,P=0.000). The CNRs tended to be lower in females (CNR:30.57±7.88) than in males (CNR:28.42±7.28); however, this difierence was not significant (t=-1.700,P=0.091). The CNR of DSCP positively correlated with patients’ age (r=0.178,P=0.032) by bivariate correlation. The ADC value was significantly lower in the DSCP (698.37±37.13×10-6mm2/s) than in the PAG (740.50±42.57×10-6mm2/s); the difierence was significant (t=-12.537,P=0.000). The ADC values tended to be higher in males (702.31±36.90×10-6mm2/s) than in females (694.68±37.21×10-6mm2/s); however, this difference was not significant (t=1.240, P=0.217). The ADC value of DSCP was not correlate with age (r=0.054, P=0.522) by bivariate correlation.Conclusion: The SI of DSCP is usually higher than that of PAG on axial DWI which significantly positively correlated with patients’ age but not with patients" gender, and the ADC value of DSCP shows no correlation with gender or age. Therefore, the regional signal variation should not be negligible when evaluating signal characteristics of the inferior midbrain on DWI. Part three: Signal intensity of the decussation of superior cerebellar peduncle on sagittal DWI: correlation with age and genderPurpose: This study is to evaluate the signal characteristics of the DSCP on sagittal DWI and furture investigate relationship between diffusion-weighted SI and ADC value of the DSCP and age and gender in healthy subjects.Materials and Methods: Sagittal diffusion-weighted images (spin-echo planar imaging sequence. TR/TE,3200/94ms; diffusion gradient encoding in three orthogonal directions: b=0,1000s/mm2; matrix,192×192; section thickness,5mm; no intersection gap. and FOV,230mm) of the brain were evaluated retrospectively in77neurologically normal subjects (37men，40women; age range:10-79years, mean age:50.4years). The signal of DSCP was divided into low signal, isointense and high signal. The signal characteristics of DSCP on sagittal DWI were evaluated conscnsually by two neuroradiologists. Assessment of the SIs was done by one radiologist and by placing polygonal shaped ROIs in the DSCP, superior midbrain， and the background of images. Background signal was measured in the pontine basement on the same image. Noise was defined as the standard deviation (SD) of the SI within a ROI outside the head (i.e., air). Contrast-to-noise ratios (CNR) of the DSCP and the superior midbrain were calculated. Two-paired samples t-test was used to evaluate the SI difference between DSCP and superior midbrain. Difference of age groups was used one-way analysis of variance (ANOVA), and bivariate correlation analysis were performed to evaluate the effects of gender and age, and Pearson correlation coefficient (r) was obtained.Results:In77healthy patients, ninety-one percent of DSCP were hyperintense (70/77),9%of them were isointense (7/77), compared to the superior midbrain. In contrast, a hypointense appearance was not seen at all in any of age groups. For quantitative interpretation, the CNR was significantly higher in the DSCP (12.50±2.77) than in the superior midbrain (5.50±2.02;t=24.59,P=0.000). The CNRs tended to be lower in females than in males (12.08±2.58vs12.88±2.92); however, this difference was not significant (t=-1.264, P=0.210). The CNR of DSCP significantly positively correlated with patients’age (r=0.421, P=0.000) by bivariate correlation. The ADC value was significantly lower in the DSCP (676.65±35.62×10-6mm2/s) than in the superior midbrain (736.69±40.58×10-6mm2/s); the difference was significant (t=-14.31, P=0.000). The ADC values tended to be higher in males (682.59±34.59×10-6mm2/s) than in females (671.15±36.10×10-6mm2/s); however, this difference was not significant (t=1.418, P=0.160). The ADC value of DSCP significantly negatively correlated with patients’age (r=-0.246,P=0.031) by bivariate correlation.Conclusion:The DSCP frequently displays high SI on sagittal DWI in the neurologically normal brain. Diffusion signal of the DSCP increased with advancing age, but its ADC value decreased with advancing age. Both SI and ADC value of the DSCP showed no correlation with gender. Therefore, the regional signal variation should not be negligible when evaluating signal characteristics of the inferior midbrain on DWI. especially, in older adults. DWI combined with the ADC maps would help to evaluate signal characteristics and pathological changes of midbrains. |
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