{"title":"Assessing the Resolution of Transcranial Magnetic Stimulation by Measuring the Magnetic Flux Density at the Cortical Surface","authors":"Aya Sato;Tetsuya Torii","doi":"10.1109/TMAG.2025.3556992","DOIUrl":null,"url":null,"abstract":"Transcranial magnetic stimulation (TMS) is a noninvasive and localized stimulation technique. Local stimulation is useful for studying brain functions and treating brain disorders. Previous studies have reported a stimulus resolution of approximately 5 mm or a stimulus area smaller than 50 mm2. Stimulus resolution has previously been evaluated using various measurement techniques. In this study, the magnetic flux density measured using a simplified system was analyzed using the quality factor (Q)-value. Magnetic pulses (at 75% intensity) were delivered using a figure-eight-shaped flat coil to a curved-head model. A distance of 15 mm from the stimulus coil to the center of the sensor coil was assumed as the same distance from the scalp to the cortex. The stimulation resolution was evaluated based on the magnetic flux density measured on the surface of the curved-head model, and the size of the stimulation area was evaluated based on the Q value. The results revealed that in both the x- and y-axes directions, the stimulation resolution on the cortical surface was less than 2 mm (<inline-formula> <tex-math>${p} \\lt 0.01$ </tex-math></inline-formula>). The Q-values from the peak to −0.1 and −3.0 dB were estimated at approximately 7.0 and 0.8 and at approximately 4.0 and 0.6 along the x- and y-axes, respectively. These results suggest that the use of a curved-head model enabled the TMS device to stimulate a target in a narrow resolution range and that Q-values can be used to easily evaluate the stimulation area.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 9","pages":"1-5"},"PeriodicalIF":1.9000,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Transactions on Magnetics","FirstCategoryId":"5","ListUrlMain":"https://ieeexplore.ieee.org/document/10947622/","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
引用次数: 0
Abstract
Transcranial magnetic stimulation (TMS) is a noninvasive and localized stimulation technique. Local stimulation is useful for studying brain functions and treating brain disorders. Previous studies have reported a stimulus resolution of approximately 5 mm or a stimulus area smaller than 50 mm2. Stimulus resolution has previously been evaluated using various measurement techniques. In this study, the magnetic flux density measured using a simplified system was analyzed using the quality factor (Q)-value. Magnetic pulses (at 75% intensity) were delivered using a figure-eight-shaped flat coil to a curved-head model. A distance of 15 mm from the stimulus coil to the center of the sensor coil was assumed as the same distance from the scalp to the cortex. The stimulation resolution was evaluated based on the magnetic flux density measured on the surface of the curved-head model, and the size of the stimulation area was evaluated based on the Q value. The results revealed that in both the x- and y-axes directions, the stimulation resolution on the cortical surface was less than 2 mm (${p} \lt 0.01$ ). The Q-values from the peak to −0.1 and −3.0 dB were estimated at approximately 7.0 and 0.8 and at approximately 4.0 and 0.6 along the x- and y-axes, respectively. These results suggest that the use of a curved-head model enabled the TMS device to stimulate a target in a narrow resolution range and that Q-values can be used to easily evaluate the stimulation area.
期刊介绍:
Science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage. The IEEE Transactions on Magnetics publishes scholarly articles of archival value as well as tutorial expositions and critical reviews of classical subjects and topics of current interest.