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The array's enclosure should form an obturator for cervical cancer brachytherapy, allowing integration with MRI\u2010guided catheter placement, CT, and interstitial radiation dose delivery.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>The endovaginal array consisted of forward\u2010looking and sideways\u2010looking components. The forward\u2010looking element imaged the cervix and posterior endometrium, and the sideways\u2010looking elements imaged the vaginal wall. Electromagnetic simulation was performed to optimize the geometry of a forward\u2010looking coil placed on a conductive\u2010metallic substrate, extending the forward penetration above the coil's tip. Thereafter, an endovaginal array with one forward\u2010looking coil and four sideways\u2010looking elements was constructed and tested at 1.5 Tesla in saline and gel phantoms, and three sexually mature swine. Each coil's tuning, matching, and decoupling were optimized theoretically, implemented with electronic circuits, and validated with network\u2010analyzer measurements. The array enclosure emulates a conventional brachytherapy obturator, allowing use of the internal imaging array together with tandem coils and interstitial catheters, as well as use of the enclosure alone during CT and radiation delivery. To evaluate the receive magnetic field () spatial profile, the endovaginal array's specific absorption\u2010rate (SAR) distribution was simulated inside a gel ASTM phantom to determine extreme heating locations in advance of a heating test. Heating tests were then performed during high SAR imaging in a gel phantom at the predetermined locations, testing compliance with MRI safety standards. To assess array imaging performance, signal\u2010to\u2010noise\u2010ratios (SNR) were calculated in a saline phantom and in vivo. Swine images were acquired with the endovaginal array combined with the scanner's body and spine arrays.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Simulated  profiles for the forward\u2010looking lobe pattern, obtained while varying several geometric parameters, disclosed that a forward\u2010looking coil placed on a metal\u2010backed substrate could double the effective forward penetration from approximately 25 to \u223c40\u00a0mm. An endovaginal array, enclosed in an obturator enclosure was then constructed, with all coils tuned, matched, and decoupled. The ASTM gel\u2010phantom SAR test showed that peak local SAR was 1.2 W\/kg in the forward\u2010looking coil and 0.3 W\/kg in the sideways\u2010looking elements, well within ASTM\/FDA\/IEC guidelines. A 15\u2010min 4 W\/kg average SAR imaging experiment resulted in\u00a0less than\u00a02<jats:sup>o<\/jats:sup>C temperature increase, also within ASTM\/FDA\/IEC heating limits. In a saline phantom, the forward\u2010looking coil and sideways\u2010looking array's SNR was four to eight times, over a 20\u201330\u00a0mm field\u2010of\u2010view (FOV), and five to eight times, over a 15\u201325\u00a0mm FOV, relative to the spine array's SNR, respectively. In three sexually mature swine, the forward\u2010looking coil provided a 5\u00a0+\u00a00.2 SNR enhancement factor within the cervix and posterior endometrium, and the sideways\u2010looking array provided a 4\u00a0+\u00a00.2 SNR gain factor in the vaginal wall, relative to the Siemens spine array, demonstrating that the array could significantly reduce imaging time.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Higher SNR gynecological imaging is supported by forward\u2010looking and sideways\u2010looking coils. A forward\u2010looking endovaginal coil for cervix and parametrium imaging was built with optimized metal backing. Array placement within an obturator enhanced integration with the brachytherapy procedure and accelerated imaging for detecting postexternal\u2010beam residual tumors.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.15228","type":"journal-article","created":{"date-parts":[[2021,9,14]],"date-time":"2021-09-14T17:04:26Z","timestamp":1631639066000},"page":"7283-7298","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["An endovaginal MRI array with a forward\u2010looking coil for advanced gynecological cancer brachytherapy procedures: Design and initial results"],"prefix":"10.1002","volume":"48","author":[{"given":"Akbar","family":"Alipour","sequence":"first","affiliation":[{"name":"Department of Medicine Johns Hopkins University  Baltimore Maryland USA"},{"name":"Department of Radiology Mount Sinai School of Medicine  New York New York USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akila N.","family":"Viswanathan","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology &amp; 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