Direct Visualization of Anatomic Subfields within the Superior Aspect of the Human Lateral Thalamus by MRI at 7T

Abstract

BACKGROUND AND PURPOSE:The morphology of the human thalamus shows high interindividual variability. Therefore, direct visualization of landmarks within the thalamus is essential for an improved definition of electrode positions for deep brain stimulation. The aim of this study was to provide anatomic detail in the thalamus by using inversion recovery TSE imaging at 7T.

The Regulatory Role of the Human Mediodorsal Thalamus

“…Acquisitions are typically study and nuclei specific. Prior reports employed inversion recovery-turbo spin echo [105] for imaging the dorsal thalamus, susceptibility-weighted imaging [106] for its ventral intermediate aspects, and MPRAGE sequences that nullify white matter that separates several nuclei [107] . A trade-off is needed between SNR and acquisition times.…”

“…A trade-off is needed between SNR and acquisition times. Shorter acquisition times help minimize movement artifacts due to head motion or cerebrovascular pulsation [105] , while longer acquisition times allow for higher-resolution images, decreasing the mixture of tissues in a voxel. Typically, 7-T MRI sequences with discernable nuclei had acquisition times of 7–15 min for image resolutions varying from 0.67 mm isotropic to 0.375 × 0.375 × 1 mm 3 [107] .…”

Visualizing the Human Subcortex Using Ultra-high Field Magnetic Resonance Imaging

“… In vivo Patient Brain tumors 25 10/15 48.6 (n.s.) Hammond et al ( 2008b ) 7.0 GE cau, gp, put, tha In vivo Control – 13 8/5 40.15 (14.19) In vivo Patient Relapse remitting MS 19 16/6 42.32 (12.9) Kanowski et al ( 2014 ) 7.0 Siemens other In vivo Control – 5 3/2 21–28 Keren et al ( 2015 ) 7.0 Brucker other PM Patient AD 7 4/3 76.4 (9.5) Kerl et al ( 2012 ) 7.0 Siemens rn, sn, stn, other In vivo Control – 9 4/5 25 (n.s.) Kerl ( 2013 ) 7.0 ...…”

“…Using UHF MRI several of the thalamic subnuclei can now be visualized in individual space without the need to refer to standardized atlases (Tourdias et al 2014 ; Saranathan et al 2014 ; Kanowski et al 2014 ). However, a large and growing number of subcortical structures can be visualized using UHF MRI, many of which have been demonstrated in a single publication.…”

Recent applications of UHF‐MRI in the study of human brain function and structure: a review

“…Adjusting the inversion time accordingly allows for the signal nulling of CSF, resulting in FLAIR (fluid‐attenuated inversion recovery) imaging. The value of this approach was exploited in studies visualizing intra‐thalamic and hippocampal substructures at UHF . A clear advantage of 7 T over 1.5 T in demarcating the hippocampus, its internal features and the hippocampal mantle was shown by using a battery of MR sequences, including FLAIR, dual‐echo TSE (resulting in PD and T 2 ‐weighted images), GRE, and MPRAGE .…”