Subject: Re: MR-compatible headphones: Koss medical ESP 900 From: Gerry Stefanatos <gstefana(at)EINSTEIN.EDU> Date: Mon, 8 Nov 2004 22:23:38 -0500Dear Yoshiko: We are currently using the Koss headphones and are reasonably pleased with them. Others I know have been less enamoured. There are several modifications that various labs have implemented, mainly to improve sound isolation and reduce susceptibility artifact. I have prepared a narrated PowerPoint presentation on the general topic of auditory fMRI which should be posted in the online methodology seminars series at NCRRN.org in the next two weeks. This will have a discussion not not only of the Koss headphones but other alternatives for auditory presentation in fMRI environments. However, I can summarize some of the changes that have been implemented to the Koss headphones here. Firstly, it is common to remove the electrostatic transducers from the factory enclosures and fit them into MRI compatible ear defenders to improve sound isolation. Some labs have utilized Bilsom ear defenders while we have found that a pair of 3M ear defenders is satisfactory. This can improve isolation from scanner noise by 30+dB. The unmodified Koss headphones produce a modest amount of susceptibility artifact, probably oweing to residual copper wiring. So, some labs have replaced the copper wiring to the transducers with carbon fiber cable. Thirdly, some labs have installed MRI compatible resistors. These modifications are described by Featherstone and colleagues from the Institute of Neurology in London. They have been working on developing and testing various modifications to these units and have presented their findings at some imaging meetings. Hope this is helpful. Gerry Gerry A. Stefanatos, D. Phil. Director, Cognitive Neurophysiology Laboratory Moss Rehab Research Institute Albert Einstein Medical Center 1200 W. Tabor Rd. Philadelphia, PA 19141 Tel: (215) 456-5962 Fax: (215) 456-5926 >>> Yoshiko Yamada <yyamada(at)DARKWING.UOREGON.EDU> 11/08/04 6:58 PM >>> Hi, I'm wondering if anyone on this list is using or knows someone (or a lab) who is using Koss 'medifcal ESP 900', which is a model of MR-compatible headphones, for auditory fMRI studies. When I talked to a sales rep at Koss, I was told that although this model is MR-compatible, each lab makes a bit of modification to meet their needs. We are wondering what kind of modification is made and why since sales rep didn't know the details about what was done to the headphones. Our lab has been looking for a set of MR-compatible electrostatic headphones for auditory language fMRI studied and considering purchasing this model, but we'd like to gether more information about compatibility of the headphones with fMR image acquisition. Thank you for your info!