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Abstract #2311

Improved Direct Localization of the Human Pedunculopontine Nucleus (PPN) by 3D FLASH MRI at Sub-Millimeter Resolution

Tobias M. Lindig1,2, Sorin Breit1, Ludger Schls1, Thomas Ngele, Uwe Klose2, Gunther Helms3

1Department of Neurology and Hertie-Institute for Clinical Brain Research, University Hospital Tuebingen, Tuebingen, Germany; 2Section of experimental MR of the CNS, Department of Diagnostic and Interventional Neuroradiology, University Hospital Tuebingen, Tuebingen, Germany; 3MR-Research in Neurology and Psychiatry, University Medical Center Goettingen, Goettingen, Germany

The pedunculopontine nucleus (PPN) is a potential target for deep brain stimulation to address symptoms of gait freezing and postural instability in Parkinsons disease. Proton density-weighted (PD-w) MRI has been recommended to locate its position. Contrast and delineation of the PPN area in healthy subjects were improved by multi-echo 3D MRI at an increased resolution of 0.8 mm^3, and by using signal amplitude maps S0. These were calculated from a dual-angle FLASH protocol, thus eliminating the residual influence of T1 from the PD-w images. Usefulness for stereotactic planning was verified on two patients at 3T using a protocol of 4x4minutes.