The mechanism of hyperintense signal at interpeduncle region on diffusion weighted imaging / 中华放射学杂志

ABSTRACT

Objective To study the mechanism of hyperintensed signal at interpeduncle region in meseneephalon on DWI with diffusion sensitive gradient(Gd)applied perpendicular to the slice direetion (DWIs).Methods MRI scanning was centered at interpeduncle region.and the protocols were as follows(1)With electrocardiograph(ECG)triggering,DWIs was acquired during systole or diastole periods respectively.(2)To observe the shape of hyperintense signal,DWIs with various slice directions was applied,which was set parallel to skull base,along Y axis,or along the oblique line between Y and Z axis with 30°to Z axis.(3)Fiber tracking was performed with the hyperintense signal as"seed"region,fractional anisotropy(FA)and ADC were derived from(multiple directions diffusion weighted imaging,MDDW).FA and ADC of hyperintease region were compared with those of the nearby fiber by using pair t-tesL Results Signal intensitv of hyperintense region on DWIs were 2296.28±38.19 and 153.81±37.91 for b=0 and b=1000 at systole period.while they were 295.36±38.84 and 154.03±37.52 at diastole period.No staffstical difference wag demonstrated between them(t=1.34,0.62,P＞0.05).The ADC valus on DWIs acquired during systole and diastole periods were(6.07±2.20)×10-4and(6.69±1.44)×10-4 mm2/s respectively.There was rio statistical difference between them(t=0.94,P＞0.05).DTI fiber tracking verified that the hyperintense region located at the decussation of superior eerebelum peduncle(SCP)in mesencephalon.It was in long and narrow heart shape or rectangular shape on DWIs.The shape depended on the direction of Gd The ADC value derived from MDDW at hyperintense region and the fiber below were(10.61±3.42)×10-4 and(9.24±2.21)×10-4 mm2/s respectively.No statistical difference was demonstrated between them(t=0.61.P＞0.05).While,the FA at hyperintensed region 0.43±0.13 was less than that of the fiber below 0.61±0.08(t=8.32.P＜0.05).Conclusions The shape of the hyperintense region on DWIs depends on the direction of Gd.The cardiac period has no effects on the hyperintense signal at peduncles,which may be attributed to the anisotropy of SCP decussation in mesencephalon.