Abstract
Delineation of the subthalamic nuclei (STN) on MRI is critical for deep brain stimulation (DBS) surgery in patients with Parkinson’s disease (PD). We propose this retrospective cohort study for quantitative analysis of MR signal-to-noise ratio (SNR), contrast, and signal difference-to-noise ratio (SDNR) of the STN on pre-operative three-dimensional (3D) stereotactic MRI in patients with medication-refractory PD. Forty-five consecutive patients with medication-refractory PD who underwent STN-DBS surgery in our hospital from January 2018 to June 2021 were included in this study. All patients had whole-brain 3D MRI, including T2-weighted imaging (T2WI), T2-weighted fluid-attenuated inversion recovery (FLAIR), and susceptibility-weighted imaging (SWI), at 3.0 T scanner for stereotactic navigation. The signal intensities of the STN, corona radiata, and background noise were obtained after placing regions of interest (ROIs) on corresponding structures. Quantitative comparisons of SNR, contrast, and SDNR of the STN between MR pulse sequences, including the T2WI, FLAIR, and SWI. Subgroup analysis regarding patients’ sex, age, and duration of treatment. We used one-way repeated measures analysis of variance for quantitative comparisons of SNR, contrast, and SDNR of the STN between different MR pulse sequences, and we also used the dependent t-test for the post hoc tests. In addition, we used Mann–Whitney U test for subgroup analyses. Both the contrast (0.33 ± 0.07) and SDNR (98.65 ± 51.37) were highest on FLAIR (all p < 0.001). The SNR was highest on SWI (276.16 ± 115.5), and both the SNR (94.23 ± 31.63) and SDNR (32.14 ± 17.23) were lowest on T2WI. Subgroup analyses demonstrated significantly lower SDNR on SWI for patients receiving medication treatment for ≥13 years (p = 0.003). In conclusion, on 3D stereotactic MRI of medication-refractory PD patients, the contrast and SDNR for the STN are highest on FLAIR, suggesting the optimal delineation of STN on FLAIR.
Highlights
Most patients with Parkinson’s disease (PD) are treated with medication, and a multitude of dopamine-enhancing agents is available as the therapeutic option (Armstrong and Okun, 2020)
Compared with the adjacent white matter structures, the Subthalamic nuclei (STN) is relatively hypointense on T2-weighted imaging (T2WI), T2-weighted fluid-attenuated inversion recovery (FLAIR), and susceptibility-weighted imaging (SWI)
Indirect targeting of the STN with CT coordinates for stereotactic localization is rapid (Spiegelmann and Friedman, 1991); anatomic details of the STN on CT are poor when compared with MRI (Lemaire et al, 1999)
Summary
Most patients with Parkinson’s disease (PD) are treated with medication, and a multitude of dopamine-enhancing agents is available as the therapeutic option (Armstrong and Okun, 2020). The drawback of the indirect targeting method, is that STN sizes, shapes, and positions vary between patients (Chandran et al, 2016). With the advancement of MRI imaging techniques, delineation of the deep brain nuclei became possible on MRI at 3.0 T. The direct targeting method, which involves attempting to locate the STN in each patient, has become the mainstream targeting technique for DBS surgery (Larson et al, 2012). Whole-brain three-dimensional (3D) stereotactic MR with T1-weighted imaging (T1WI), T2WI, FLAIR, and SWI are obtained for trajectory planning before DBS surgery (Chandran et al, 2016). Delineating the STN on MRI is vital for the direct targeting method employed in the DBS surgery. The signal intensities (SIs) of the STN and surrounding white matter structures, vary on by MR pulse sequences, which may influence the ability to differentiate between these structures (Wolff and Balaban, 1997)
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