Utility of Combining Transcranial Sonography and MIBG Myocardial Scintigraphy to Evaluate Substantia Nigra in Patients with Parkinson's Disease.

The utility of transcranial sonography (TCS) remains unclarified for the auxiliary diagnosis of Parkinson's disease (PD). We investigated iodine-123 metaiodobenzylguanidine (MIBG) and TCS during the examination and diagnosis of high-signal-intensity substantia nigra lesion (HSI-SNL) incidence in PD patients previously diagnosed with dopamine transporter scintigraphy (DAT). The subjects were 67 patients with definitively diagnosed PD after DAT evaluation. Patients with midbrain substantia nigra visible during TCS who previously underwent MIBG were analyzed. The SN+ group comprised patients with extensive pathological HSI-SNL of Okawa class III/IV observed during TCS. The MIBG+ group comprised patients with a heart-to-mediastinum ratio of ≤2.2 during MIBG. TCS was performed to divide patients into the SN+ and SN- groups, and patient characteristics and MIBG findings were compared between the groups. PD was definitively diagnosed in 67 patients, among whom midbrain was visualized during TCS in 43 (64.1%) patients and pathological HSI-SNL was observed in 24 (35.8%). The MIBG findings were normal in six patients (27.3%) with HSI-SNL, and abnormal in seven (63.6%) without HSI-SNL. No significant differences were noted by Okawa classification in clinical characteristics based on the presence or absence of HSI-SNL. Multiple patients with normal findings during MIBG may have HSI-SNL. Thus, confirmatory imaging of HSI-SNL with TCS may be useful for diagnosis.

Effectiveness and safety of MR-guided focused ultrasound thalamotomy in patients with essential tremor and low skull density ratio: a study of 101 cases.

OBJECTIVE: The objective was to investigate the effectiveness and safety of MR-guided focused ultrasound (MRgFUS) treatment in patients with essential tremor, particularly those with low skull density ratio (SDR) and including those with very low SDR, and to identify the factors influencing treatment effectiveness and to provide insights into therapeutic approaches for patients with lower SDR. METHODS: Real-world data from 101 patients who underwent MRgFUS between July 2019 and March 2022 at a single institution were analyzed. Tremor severity was assessed using the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (CRST). The patients were categorized into quartile groups based on their mean SDR, and the characteristics, treatment effectiveness, treatment parameters, and adverse events were evaluated among these subgroups. RESULTS: Patients were classified into 4 quartiles based on the mean SDR: quartile 1 (Q1) (SDR 0.26-0.37), Q2 (SDR 0.38-0.42), Q3 (SDR 0.43-0.49), and Q4 (SDR 0.50-0.75). MRgFUS significantly improved total CRST and tremor score across all SDR subgroups. Additionally, there were no significant differences in the improvement rates among the 4 subgroups. Analysis of the treatment parameters revealed that lower mean SDR was associated with lower target maximum temperature and smaller coagulation volume after focused ultrasound (FUS). Regarding adverse events, headache and nausea during FUS and facial and head edema on the day after surgery were more frequent in the Q1 subgroup (very low-SDR group). In contrast, numbness was more common in the Q4 subgroup. However, all these adverse events had resolved by the 3-month follow-up except numbness. CONCLUSIONS: This study suggested that MRgFUS is effective and safe for patients with medication-resistant essential tremor, including those with very low mean SDR. However, the very low-SDR group had insufficient temperature elevation at the target site compared with the high-SDR group, suggesting the need for a different strategy. Notably, with careful adjustments and considerations, positive outcomes can still be achieved in patients with very low SDR. Therefore, very low SDR should not be considered an absolute exclusion criterion because it is expected to increase the number of patients who benefit from MRgFUS.

Video Motion Analysis as a Quantitative Evaluation Tool for Essential Tremor during Magnetic Resonance-Guided Focused Ultrasound Thalamotomy.

The Clinical Rating Scale for Tremor (CRST) is commonly used to evaluate essential tremor (ET) during focused ultrasound (FUS) thalamotomy. However, it faces challenges such as the ceiling effect and test-retest variability. This study explored the utility of videographic motion analysis as an evaluation index for ET. Forty-three patients with ET performed postural tremor and line-drawing tasks recorded on video, and the data were analyzed using motion analysis software. The test-retest and inter-rater reliability, correlations with the CRST and tremor scores, and pre/post-FUS treatment comparisons were analyzed. The video motion analysis showed excellent test-retest and inter-rater reliability. In the postural tremor tasks, video parameter amplitude significantly correlated with the CRST and tremor scores. Similarly, for the line-drawing task, video parameter amplitude showed significant correlations with CRST and tremor scores, effectively addressing the ceiling effect. Regarding post-FUS treatment improvements, changes in the CRST and tremor scores were significantly associated with changes in video parameter amplitude. In conclusion, quantitative analysis of the video motion of ET enables precise evaluation of kinematic characteristics and effectively resolves the ceiling effect and test-retest variability. The video motion analysis score accurately reflected the tremor severity and treatment effects, demonstrating its high clinical utility.