Objective: To investigate the usefulness of transcranial ultrasonography (TCS) in the diagnosis of Japanese patients with Parkinson’s disease (PD).

Background: There are many reports on the usefulness of TCS in the diagnosis of PD in Westerners, but there are few reports in Japanese because it is difficult to observe the midbrain in elderly Asian women.

Method: The subjects comprised 63 patients (21 men, 11 women) with PD. The diagnosis of PD was based on dopamine transporter scintigraphy showing an age-calibrated specific binding ratio <95% CI to meet the MDS diagnostic criteria. Early and late images were obtained with myocardial MIBG scintigraphy, and the heart-to-mediastinum (H/M) ratio was abnormal when the ratio was ≤2.2 on the early image or ≤1.8 on the late image and the washout rate was ≤34%. For TCS, an ultrasonic diagnostic device (XARIO XG, Toshiba Medical Systems) was used. Using a sector probe, the midbrain was observed via the temporal bone window approach at 2.5 MHz and 50-60 dB settings. The change in brightness was evaluated according to the qualitative classification of Okawa et al., with ≥3 degrees regarded as abnormal. Patients were classified into the TCS normal group (normal substantia nigra [SN] brightness) and TCS abnormal group (abnormal SN brightness), and the early/late H/M ratios and MIBG washout rate were compared and examined. The t-test was used for the analysis, and the significance level was set to 5%.

Results: The brightness of the SN could be evaluated by TCS in 32 of 63 cases, of which 25 of the 32 cases showed abnormalities in myocardial MIBG, and 22 cases showed abnormal SN on TCS. When the early H/M ratio, late H/M ratio, and washout rate of MIBG were compared between the TCS normal group and the TCS abnormal group, no significant difference was observed in any of the values (early H/M ratio: TCS normal group 2.06 ± 0.69, TCS abnormal group 1.94 ± 0.49, p = 0.580; late H/M ratio: TCS normal group 1.84 ± 0.76, TCS abnormal group 1.56 ± 0.60, p = 0.246; washout rate: TCS normal group 58.7 ± 24.6, TCS abnormal group 66.4 ± 22.7, p = 0.383).

Conclusion: TCS is a test that can visually evaluate the SN quickly and is independent of MIBG. In the diagnosis of PD, the combination of nuclear medicine tests and TCS may provide clinically useful information.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/usefulness-of-substantia-nigra-evaluation-by-transcranial-ultrasonography-in-the-diagnosis-of-parkinsons-disease/