[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-83149-en":3,"doc-seo-83149-105":29,"detail-sidebar-cat-0-en-105":91},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":13,"seo_description":14,"update_tm":27,"read_time":28},83149,687197207057,"Sage","https://ap-avatar.wpscdn.com/davatar_29158cc5080c5b710cf443261637dec0",8,"Research & Report","Optical Detuning Strategies for Shielded Loop Resonators","Optical detuning strategies for shielded-loop resonators (SLR) are evaluated to match conventional galvanic detuning while reducing RF-field sensitivity issues in dense clinical MRI receive arrays. Four optical detuning approaches are compared via simulations, bench testing, and phantom experiments at 3T, alongside passive wireless detuning. Optical power needs are analyzed, and a flexible optically-detuned four-channel SLR array is built and validated in vivo for knee and brain imaging.","Optical Detuning Strategies for Shielded Loop Resonators  \nJakob Gerlach 1 *, Reza Aghabagheri 1, Zining Liu 1, Shuai Liu 1, Morteza Teymoori2, Çağlar Ataman2, Michael Bock 1, Ali Caglar Özen 1  \n1Division of Medical Physics, Department of Radiology, University Medical Center Freiburg, University of Freiburg, Freiburg, Germany 2Microsystems for Biomedical Imaging Group, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany  \n2757/2800 Words  \n*Correspondence: Jakob Gerlach  \nDivision of Medical Physics, Department of Radiology, University Medical Center Freiburg, University of Freiburg, Freiburg, Germany.  \n[Email: jakob.gerlach@uniklinik-freiburg.de](Email: jakob.gerlach@uniklinik-freiburg.de)  \nABSTRACT  \nPurpose: To compare detuning performance and evaluate power requirements of optical detuning methods and to demonstrate feasibility of an optically-detuned four-channel receive array.  \nMethods: Four optical detuning methods were compared in simulations, bench tests, and phantom measurements at 3T against conventional galvanic detuning. Passive detuning was also tested as an additional wireless detuning option. Optical power requirements for the detuning networks were investigated, and a flexible optically-detuned 4-channel shielded-loop resonator (SLR) array was constructed and tested in vivo.  \nResults: A photodiode-PIN diode combination exhibited the highest unloaded Q (68 .6) and Q ratio (1 .9), with detuning performance and signal-to-noise ratio comparable to that of galvanic detuning atan optical power of 10 mW. Using this detuning strategy, in vivo images of the knee and brain were successfully acquired with a 4-channel flexible array.  \nConclusion: Optical detuning is a practical alternative to conventional galvanic detuning in flexible SLR arrays. With developments in optical signal and power transmission, optimizing optical detuning while meeting manageable power requirements is an important step toward fully optical receive coil arrays. This study provides a baseline for the total optical power required for active detuning in such optical coil systems.  \nKeywords: Optical detuning, Flexible receive array, Shielded-loop resonator, Photodiode, Light Coils  \nINTRODUCTION  \nIn clinical MRI systems, local receive (Rx) coils are connected to the receiver system via coaxial cables. Particularly in dense receive arrays, galvanic cable connections can introduce problems such as cable clutter, signal crosstalk, and interactions with the radio frequency (RF) excitation pulses. Although benefits in SNR and acceleration factor have been demonstrated for a simulated 256-channel array [1], in practice, the maximum number of channels in a head coil has been limited to 128 [2] . To overcome these challenges, optical methods have been proposed [3], [4], [5], [6], [7], [8], [9], which are insensitive to RF fields. However, in most implementations, the optical links were limited to data transfer, while active coil detuning during RF excitation and powering of amplifiers and other active components remained galvanic.  \nRecently, a fully optical signal and power transmission system was proposed [8], [9] . Here, detuning was also realized optically using a phototransistor, replacing the conventional active detuning. Alternatively, Memis et al. implemented an optically controlled detuning which was powered by oncoil batteries [3] . Wong and co-workers used a photoresistor and a manually switched light source to tune and detune a micro-coil for the localization of interventional devices [10] . Weiss et al. installed a resonant marker with a photodiode at the catheter tip for tracking [11] . Korn et al. employed optical detuning of a surface coil for motion compensation using a self-gating technique [12] . They introduced a configuration in which a photodiode supplies the current to switch the PIN diodes in the detuning circuit. A variation of this configuration was also applied by Saniour et al. for an endolum","cbCain6a9YZ7Kggu","https://ap.wps.com/l/cbCain6a9YZ7Kggu","pdf",2866515,1,24,"English","en",105,"# Abstract\n# Introduction\n# Methods","[{\"question\":\"What is the main goal of comparing optical detuning methods for SLRs?\",\"answer\":\"To compare detuning performance and evaluate power requirements of optical detuning methods, and to demonstrate feasibility of an optically-detuned four-channel receive array.\"},{\"question\":\"How were the detuning strategies evaluated in this study?\",\"answer\":\"The four optical detuning methods were compared in simulations, bench tests, and phantom measurements at 3T, including an additional passive detuning option.\"},{\"question\":\"Which optical detuning approach performed best and what was demonstrated in vivo?\",\"answer\":\"A photodiode–PIN diode combination achieved the highest unloaded Q and Q ratio with detuning and SNR comparable to galvanic detuning at 10 mW optical power, enabling in vivo knee and brain images using a four-channel flexible 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is the main goal of comparing optical detuning methods for SLRs?","Question",{"text":75,"@type":76},"To compare detuning performance and evaluate power requirements of optical detuning methods, and to demonstrate feasibility of an optically-detuned four-channel receive array.","Answer",{"name":78,"@type":73,"acceptedAnswer":79},"How were the detuning strategies evaluated in this study?",{"text":80,"@type":76},"The four optical detuning methods were compared in simulations, bench tests, and phantom measurements at 3T, including an additional passive detuning option.",{"name":82,"@type":73,"acceptedAnswer":83},"Which optical detuning approach performed best and what was demonstrated in vivo?",{"text":84,"@type":76},"A photodiode–PIN diode combination achieved the highest unloaded Q and Q ratio with detuning and SNR comparable to galvanic detuning at 10 mW optical power, enabling in vivo knee and brain images using a four-channel flexible 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