Application Of MR In The Surgery Of Deep Brain Electrical Stimulation In Parkinson’s Disease

Objective Deep-brain stimulation(DBS)of the subthalamic nucleus(STN)has shown remarkable therapeutic benefits for parkinson’s disease(PD).The success of the DBS is critically dependent on the reliable visualization of the STN.The aim of this comparative study was to find the best MRI sequences for prestereotactic visualization of the subthalamic nucleus(STN)as the operation target for deep-brain stimulation(DBS)procedure for Parkinson’s disease(PD).Methods In this prospectively designed study,MRI at 1.5 T(Siemens,Germany)of ten healthy individuals and of ten patient with PD was acquired T2-TSE,FLAIR,T1-MPRAGE,T2-SPACE,T2*-FLASH2 D,susceptibility-weighted imaging mapping(SWI).Different sequences were analyzed semi-quantitatively when applied to visualize the STN before DBS procedures.Image quality and visualization of the STN for each sequence were assessed by two neuroradiologists independently using a 6-point scale.The grading was as follows: 5 – excellent delineation;4 – good delineation;3 – moderate delineation;2 – poor delineation;1 – no delineation;0 – no image.Axial,coronal,and sagittal planes of the T2*-FLASH2 D images were compared.MRI marked area was compared with the intra-operative electrode probe positioning confirmed by microelectrode recording(MER).Results Two neuroradiologists graded the visualization of the STN for the differentsequence score as follows,T1-MPRAGE(2.70±0.657/2.90±0.553),FLAIRtra(2.65±0.671/3.10±0.553),T2-SPACE tra(3.65±0.671/3.65±0.587),T2-FLASH2 D tra(4.55±0.51/4.55±0.51),T2*-FLASH2Dsag(3.55±0.510/3.35±0.489),T2*-FLASH2Dcor(3.95±0.686/4.00±0.725),SWI tra(3.95±0.510/3.95±0.51),T2-TSE(3.35±0.671/3.20±0.696),in which T2*-FLASH2 D tra was significantly higher than that of other sequences.All sequences were Kappa test,T1-MPRAGE,FLAIR Tra,T2-TSE,T2* flash2 D sag sequence Kappa < 0.4,T2*-FLASH2 D,T2*-FLASH2 Dcor,SWI,T2-SPACE tra Kappa >0.4,which T2* flash2 D tra was high inter-rater reliability.T2*-FLASH2 D images was higher consistency with the positioning of electrodes implanted for deep brain stimulation.Conclusion T2*-FLASH2 D,T2-TSE and SWI sequences can providesoptimal and reliable delineation of the STN.Particularly,the axial and to a lesser degree the coronalof the STN on the T2*-FLASH2 D images.accurate targeting for subthalamic nucleus deep brain stimulation,shorten preoperative preparation time and improve the objectivity of target prospecting,thus can reduce intra-operative microelectrode probing times,and can further shorten the operation time and reduce the risks of DBS procedures.Objective Imaging has an essential role in the evaluation ofcorrect positioning of electrodes implanted for deep brainstimulation(DBS).Although MRI offers superior anatomicvisualization of target sites,there are safety concerns in patients with implanted material;To explore the accuracy and clinical clinlcal value of the electrodes electrode position in deep brain stimulation(DBS)procedure by use of image fusion technique of post-operative CT with pre-operative MRI in patients with Parkinson’s Disease(PD).Methods In this prospectively designed study,32 cases of Parkinson’s disease patients who underwent bilateral deep brain stimulation from April 2015 to March 2016 were acquired,In all candidates,the Unified Parkinson’s Disease Rating Scale III(UPDRS III)score was evaluated before and after the surgery of PD patients.Acute Levodopa challenge test(ALCT)of the maximum improvement rate weregreater than30%.The protocol consisted of a preoperative MRI 、a postoperative CTperformed 1 hour after surgery for DBS anda postoperative MRI performed 2~3 weeks after surgery for DBS.Preoperative high-resolution T2-weighted sequences at 1.5T,and postoperative CT serieswere fused using a Leksell software.Electrode tip position was measured on the obtained imagesin three directions(in relation to the midline,the AC-PC lineand an AC-PC line orthogonal,respectively).The electrodes position and examination time of each patient were compared between fusion images and conventional MRI.This study was compared the electrodes position accuracy and examination time on fusion imagesof post-operative CT and pre-operative MRI and those on post-operative MRI,then the results were for statistical analysis.Results(1)Clinical Outcome:There was a rapid and significant improvement of motor symptoms,especially tremor and rigidity,after STN stimulation,with low morbidity.For all patients,the preoperative UPDRS scores before and after using levodopa were 48.8±20.7 and 9.6±9.6.The postoperative UPDRS score before and after using levodopa and after the machine was turned on was 24.8±13.0 and 4.8±3.3,respectively.the maximum improvement rate of Acute Levodopa challenge test(ALCT)was80.7%.The off-medication andon-medication UPDSRIII scores of the patients improved withstimulation by 47.5% 、87.2% after STN DBS.(2)Two methods had high consistency : R values in left electrod were: 0.896、0.939、0.962,in right electrode were: 0.927、0.996、0.865,there were not statistically significant difference in this two methods(P>0.05);(3)Fusion group: Double electrodes tip distances to the AC-PC line average in Axial,Lateral,Vertical were: 2.67±1.38(3.23±1.45),10.29±1.67(11.61±1.76),6.96±1.96(6.88±1.38),the control group: Double electrodes tip distances to the AC-PC line average in Axial,Lateral,Vertical were : 2.81 ± 1.48(3.31 ±1.33),10.53±1.70(11.58±1.77),7.26±1.01(7.03±1.54).The differences found between measures on fussed CT/MR images and MR-only images were not statistically significant in the axial plane and in the lateral and Vertical plane of the right electrode(P> 0.05),while they were for those in the lateral and Vertical plane of the left electrode(P < 0.05),which concurs with findings in the literature.(4)post-operative MRI and post-operative CT scan time respectively were about7.65 ± 0.328 minutes and2.85±0.292 minutes,There were statistically significant difference(P < 0.05).Conclusion Application of post-operative CT and pre-operative MRI image fusion after DBS operation can accurately identify the electrodes position.This helps reduce thepotential risk encountered by post-operative MRI examination and shorten the post-operative scan time for patients.It provides a new ideas and options.safe and fast techniquefor post-operative assessment of electrode position in DBS.