Comparison of 3T and 7T MRI for the visualization of globus pallidus sub-segments

Shuki Maruyama,Masaki Fukunaga,Hans-Peter Fautz,Robin Heidemann,Norihiro Sadato

doi:10.1038/s41598-019-54880-x

Abstract

The success of deep brain stimulation (DBS) targeting the internal globus pallidus (GPi) depends on the accuracy of electrode localization inside the GPi. In this study, we sought to compare visualization of the medial medullary lamina (MML) and accessory medullary lamina (AML) between proton density-weighted (PDW) and T2-weighted (T2W) sequences on 3T and 7T MRI scanners. Eleven healthy participants (five men and six women; age, 19–28 years; mean, 21.5) and one 61-year-old man were scanned using two-dimensional turbo spin-echo PDW and T2W sequences on 3T and 7T MRI scanners with a 32-channel receiver head coil and a single-channel transmission coil. Profiles of signal intensity were obtained from the pixel values of straight lines over the GP regions crossing the MML and AML. Contrast ratios (CRs) for GPe/MML, GPie/MML, GPie/AML, and GPii/AML were calculated. Qualitatively, 7T visualized both the MML and AML, whereas 3T visualized the MML less clearly and hardly depicted the AML. The T2W sequence at 7T yielded significantly higher CRs for GPie/MML, GPie/AML, and GPii/AML than the PDW sequence at 7T or 3T. The T2W sequence at 7T allows visualization of the internal structures of GPi segments with high signal intensity and contrast.

Highlights

The success of deep brain stimulation (DBS) targeting the internal globus pallidus (GPi) depends on the accuracy of electrode localization inside the GPi
Our results demonstrated that proton densityweighted (PDW) and T2W sequences at 7T almost clearly visualized both the medial medullary lamina (MML) and the accessory medullary lamina (AML)
We showed that the T2W sequence visualized both the MML and AML with significantly higher Contrast ratios (CRs) than the PDW sequence at 7T

Summary

Introduction

The success of deep brain stimulation (DBS) targeting the internal globus pallidus (GPi) depends on the accuracy of electrode localization inside the GPi. In this study, we sought to compare visualization of the medial medullary lamina (MML) and accessory medullary lamina (AML) between proton densityweighted (PDW) and T2-weighted (T2W) sequences on 3T and 7T MRI scanners. There are two theories of improving movement disorders by stimulation: one is based on the function similar to disease (inhibition)[9]; the other is the fact that high-frequency stimulation excites local neuronal elements as local single-pulse stimulation (excitation) This mechanism may include abnormal activity patterns or normalizing neuronal activity pattern[10,11,12,13], and inhibition of output nuclei within the basal ganglia circuitry. It is difficult to differentiate the GPie and GPii using conventional 1.5T or 3T MRI because the GPi segments are quite small and exhibit low contrast with the AML (Fig. 1)

Methods

Results

Conclusion