Comparison between 1.5- and 3-T Magnetic Resonance Acquisitions for Direct Targeting Stereotactic Procedures for Deep...

Deep brain stimulation (DBS) is a well-established treatment for movement disorders. High magnetic fields could have an impact on distortion. We evaluated 1.5- and 3-T magnetic resonance imaging (MRI) sequences for accuracy, precision, and trueness of our MRI-guided direct targeting protocol.

Effects of distortion on MR sequences (T1- and T2-weighted sequences) can be evaluated using a dedicated phantom (Elekta). Field strength capabilities were assessed on Siemens Avanto (1.5 T) and Skyra (3 T) scanners. We assessed the precision of our stereotactic MRI-guided procedure.

We focused on the risk of error due to a high field strength. Error values on the localizer box were between 0.4 and 0.7 mm at 1.5 T and between 0.6 and 2 mm at 3 T. The most accurate 1.5-T sequence is the 3D FLASH T1-weighted sequence, which had an accuracy value of 0.6 mm. At 3 T, the accuracy value of the isotropic 3D FLASH T1-weighted sequence was 1.6 mm.

Given the millimetric size of stereotactic targets and electrodes, lead implantation for neuromodulation therapy needs to be accurate. We demonstrate that 3-T imaging could not be used for stereotaxy in our MRI-guided direct targeting protocol because of a risk of error induced by distortion.