High Resolution Imaging With Fast Gray Matter Acquisition

High Resolution Imaging With Fast Gray Matter Acquisition T 1 Inversion Recovery (FGATIR): Neuroimaging Atlas Of The Basal Ganglia Circuitry For Deep Brain Stimulation Planning Charlie Chia-Tsong Hsu 2, Gigi Nga Chi Kwan 2, Sandeep Bhuta 1, 2 1 Griffith University, School of Medicine, Southport, Queensland, Australia 2 Department of Medical Imaging, Gold Coast University Hospital, Southport, QLD, Australia

DISCLOSURE OF COMMERCIAL INTEREST • Neither I nor my immediate family members have a financial relationship with a commercial organization that may have a direct or indirect interest in the content

INTRODUCTION • Conventional methods of deep brain stimulation (DBS) involves clinical testing and microelectrode recording (MER) of neuronal signatures during awake neurosurgery for target localization. • Macroelectrode-stimulation clinical testing to confirm desirable response before to confirm final electrode positioning and pulse generator implantation.

AIM • Increasingly, hybrid techniques utilizing combination of electrophysiology and imaging guidance for target localization and electrode placement • AIM: To detailed an optimized DBS protocol for imaging localization of various DBS targets using Fast Gray Matter Acquisition T 1 Inversion Recovery (FGATIR) and diffusion tension imaging (DTI)

DBS PROTOCOL • SIEMENS Skyra 3 T scanner • Sequences: Fast Gray Matter Acquisition T 1 Inversion Recovery (FGATIR), High resolution Susecptibility Weighted Imaging (SWI), MPRAGE and Multiband accelerated EPI diffusion tensor imaging (DTI) • Post processing with Siemens Syngo and Nordic. Lab

FGATIR • FGATIR: TR 3000 ms, TE 4. 39 ms, TI 409 ms, inversion pulse angle 180 degrees, matrix 320 x 256, FOV 256 x 192 mm, slices thickness 160 x 1 mm and bandwidth of 130 Hz). • High resolution SWI: TR 3000 ms, TE 2. 86 ms, slice thickness 1 mm, FOV 240 x 81 mm, base resolution 320, phase resolution 100 and voxel size 0. 8 x 1 mm. • Multi-Band Accelerated EPI DTI: TR 5035 ms, TE 114 ms, Multi-band acceleration factor 2, diffusion direction 64, b. Value 3000, slice thickness 2. 4 mm, FOV 230 x 100 mm and voxel size 2. 4 x 2. 4 mm

IMAGING GUIDANCE IN DBS • It remains unclear if imaging guided targeting or MER is a superior technique. • Imaging guided targeting alone has been demonstrated as a reliable technique. • Signature electrophysiological recording of the targets (ie STN) may not be present in all patients. • Repeated insertion of electrodes for obtaining electrophysiological signal of targets (ie STN) has the potential to increase complication such as bleeding.

MOVEMENTS DISORDERS • DBS targets for Parkinson’s disease include the Subthalamic nucleus (STN) or globus pallidus internus (GPi) • DBS targets for essential tremor is the ventrointermediate (VIM) nucleus of the thalamus. • GPi is also a DBS targets for dystonia. J Neurosurg Sci. 2016. [Epub ahead of print]

BASAL GANGLIA C ICa AC F ICg Gi Ge P ICp H thalamus FGATIR Axial images of basal ganglia with contour colors denotes: head of caudate (light blue), lentiform nucleus (green) and thalamus (yellow). C= head of caudate, P= putamen, Ge= globus pallidus externus, Gi= globus pallidus internus, ICa=Anterior limb of internal capsule, ICg= Genu of internal capsule, ICp= Posterior limb of internal capsule, AC= anterior commissure, F= fornix, H= habenular commissure. White arrow denotes the medial medullary lamina.

BASAL GANGLIA Ge Gi P High resolution axial SWI image Showing the tri-laminar appearance of the lentiform nucleus with the more mineralized globus pallidus internus (Gpi), globus palldius externus (Gpe) and the outer less mineralized putamen.

GLOBUS PALLIDUS INTERNUS A B ICp Parasaggital images of basal ganglia structures in the (A) FGATIR and (B) FGATIR with contours overlay. The contour colors denote: caudate (light purple), GPe (yellow), GPi (green), optic tract (red) and thalamus (blue). Posterior limb of the internal capsule (Icp) passes between the globus pallidus and the thalamus. Dotted red line= medial medullary lamina.

GLOBUS PALLIDUS INTERNUS DTI tractography with MPRAGE overlay depicts the relationship of the corticospinal tract in relationship to the intended DBS traget, Gpi (dotted green circle)

GLOBUS PALLIDUS INTERNUS A B C MPRAGE with DTI overlay depicts the relationship of GPi to the post chiasmatic optic tract (arrow). The DBS trajectory and intended GPi target (dotted green circle) are labelled on the sagittal (A) and coronal images (B).

SUBTHALAMIC NUCLEI Subthalamic nucleus (STN) is divided into a large dorsolateral motor area, a ventromedial associative area, and a medial limbic area. Each area receives inputs and provides output to different target nuclei. The dorsolateral motor area is the DBS tragets for treatment of Parkinson’s disease. Neurology. 70: 1991 -1995

SUBTHALAMIC NUCLEI A B ST N FGATIR (A) and MPRAGE (B) images showing the STN. FGATIR image (A) clearly depicts the STN as a iso/mildly hyperintense linear structure outlined by the hypointense bands at its superior and inferior boundary. The superior boundary just inferior to thalamus corresponds to the zona incertia whilest the inferior boundary is the junction with susbstantia nigra.

SUBTHALAMIC NUCLEI A B Coronal FGATIR (A) and MPRAGE (B) images demarcating the STN (red line) and the trajectory to the target (white arrow).

SUBTHALAMIC NUCLEI SN Coronal FGATIR (A) and SWI (B) images demarcating the STN (red line) and the trajectory to the target (white arrow). SWI image shows Substantia Nigra (SN) and approximate location of STN in relation to SN

SUBSTANTIA NIGRA SWI axial slice at the level of nigrosome as a hyperintense band between the sustantia nigra (arrows). 1 red nucleus, 2 midbrain tegmentum, 3 aqueduct, 4 periaqueductal grey, 5 medial leminiscus, 6 nigrosome-1, 7 substantia nigra, 8 cerebral peduncle, 9 mammillary body, Swallow Tail Sign PLo. S One. 2014; 9(4): e 93814

ALZHEIMER’S DISEASE • Fornix and nucleus basalis of Meynert DBS are proposed DBS targets for Alzheimer’s disease. 1 • Phase I trial of deep brain stimulation of memory circuits in Alzheimer's disease 2 1. World Neurosurg 2013; 80: S 28. e 1 -8 2. Ann Neurol. 2010; 68: 521 -34.

FORNIX A C B AC M Sagittal FGATIR images (A-C) show the body of fornix (arrow), anterior commissure (AC), anterior/posterior column of fornix (arrow heads), mammillary body (M) and mammillothalamic tract (dotted arrow).

MAMMILLOTHALAMIC TRACT A C B AC D E M Axial FGATIR images (A-E) show the body of fornix (arrow), anterior commissure (AC), anterior/posterior column of fornix (arrow heads), mammillary body (M) and mammillothalamic tract (dotted arrow).

FORNIX Parasaggittal FGATIR image 4 mm from midline showing the trajectory of DBS electrode positioned immediately parallel to the vertical segment of body and the posterior column of fornix. The designated tip of the DBS electrode contacts the mammillary body.

FORNIX Multiplanar MPRAGE image with DTI overlay showing the DBS trajectories (arrows) along the vertical segment of the fornix body and the posterior column of fornix.

CONCLUSION • FGATIR sequence allows clear depiction of the thalamus, striatum and GPe/Gpi because of its contrast resolution • High resolution SWI enables depiction of the STN-Substantia Nigra interface. • FGATIR also reveals axonal fibers not visible on the conventional MPRAGE: the internal lamina of the GPi • Use of the FGATIR with DTI overlay assists in accurate localization of DBS targets • Utilizing FGAITR, hi resolution SWI and DTI overlay as a DBS imaging protocol can potentially have positive impact on patients clinical outcome

REFERENCES • Neuroimage. 2009; 47 Suppl 2: T 44 -52. • PLo. S One. 2014; 9(4): e 93814 • J Neurosurg Sci. 2016. [Epub ahead of print] • Neurology. 70: 1991 -1995 • World Neurosurg 2013; 80: S 28. e 1 -8 • Ann Neurol. 2010; 68: 521 -34.