{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,2,21]],"date-time":"2025-02-21T14:06:41Z","timestamp":1740146801107,"version":"3.37.3"},"reference-count":40,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2022,6,29]],"date-time":"2022-06-29T00:00:00Z","timestamp":1656460800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002347","name":"Bundesministerium f\u00fcr Bildung und Forschung","doi-asserted-by":"publisher","award":["01EO1004"],"award-info":[{"award-number":["01EO1004"]}],"id":[{"id":"10.13039\/501100002347","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002347","name":"Bundesministerium f\u00fcr Bildung und Forschung","doi-asserted-by":"publisher","award":["01EO1504"],"award-info":[{"award-number":["01EO1504"]}],"id":[{"id":"10.13039\/501100002347","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Background<\/jats:title>\n<jats:p>To investigate the effects of B<jats:sub>1<\/jats:sub>-shimming and radiofrequency (RF) parallel transmission (pTX) on the visualization and quantification of the degree of stenosis in a coronary artery phantom using 7 Tesla (7 T) magnetic resonance imaging (MRI).<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methods<\/jats:title>\n<jats:p>Stenosis phantoms with different grades of stenosis (0%, 20%, 40%, 60%, 80%, and 100%; 5 mm inner vessel diameter) were produced using 3D printing (clear resin). Phantoms were imaged with four different concentrations of diluted Gd-DOTA representing established arterial concentrations after intravenous injection in humans. Samples were centrally positioned in a thorax phantom of 30 cm diameter filled with a custom-made liquid featuring dielectric properties of muscle tissue. MRI was performed on a 7 T whole-body system. 2D-gradient-echo sequences were acquired with an 8-channel transmit 16-channel receive (8 Tx \/ 16 Rx) cardiac array prototype coil with and without pTX mode. Measurements were compared to those obtained with identical scan parameters using a commercially available 1 Tx \/ 16 Rx single transmit coil (sTX). To assess reproducibility, measurements (<jats:italic>n<\/jats:italic> = 15) were repeated at different horizontal angles with respect to the B<jats:sub>0<\/jats:sub>-field.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Results<\/jats:title>\n<jats:p>B<jats:sub>1<\/jats:sub>-shimming and pTX markedly improved flip angle homogeneity across the thorax phantom yielding a distinctly increased signal-to-noise ratio (SNR) averaged over a whole slice relative to non-manipulated RF fields. Images without B<jats:sub>1<\/jats:sub>-shimming showed shading artifacts due to local B<jats:sub>1<\/jats:sub><jats:sup>+<\/jats:sup>-field inhomogeneities, which hampered stenosis quantification in severe cases. In contrast, B<jats:sub>1<\/jats:sub>-shimming and pTX provided superior image homogeneity. Compared with a conventional sTX coil higher grade stenoses (60% and 80%) were graded significantly (p&lt;0.01) more precise. Mild to moderate grade stenoses did not show significant differences. Overall, SNR was distinctly higher with B<jats:sub>1<\/jats:sub>-shimming and pTX than with the conventional sTX coil (inside the stenosis phantoms 14%, outside the phantoms 32%). Both full and half concentration (10.2 mM and 5.1 mM) of a conventional Gd-DOTA dose for humans were equally suitable for stenosis evaluation in this phantom study.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec004\">\n<jats:title>Conclusions<\/jats:title>\n<jats:p>B<jats:sub>1<\/jats:sub>-shimming and pTX at 7 T can distinctly improve image homogeneity and therefore provide considerably more accurate MR image analysis, which is beneficial for imaging of small vessel structures.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0270689","type":"journal-article","created":{"date-parts":[[2022,6,29]],"date-time":"2022-06-29T17:31:37Z","timestamp":1656523897000},"page":"e0270689","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Effects of image homogeneity on stenosis visualization at 7 T in a coronary artery phantom study: With and without B1-shimming and parallel transmission"],"prefix":"10.1371","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6360-0578","authenticated-orcid":true,"given":"Stefan","family":"Herz","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maria R.","family":"Stefanescu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Lohr","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Patrick","family":"Vogel","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9313-9356","authenticated-orcid":true,"given":"Aleksander","family":"Kosmala","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maxim","family":"Terekhov","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8943-3539","authenticated-orcid":true,"given":"Andreas M.","family":"Weng","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jan-Peter","family":"Grunz","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thorsten A.","family":"Bley","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laura M.","family":"Schreiber","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2022,6,29]]},"reference":[{"key":"pone.0270689.ref001","doi-asserted-by":"crossref","first-page":"3232","DOI":"10.1093\/eurheartj\/ehw334","article-title":"Cardiovascular disease in Europe: epidemiological update 2016","volume":"37","author":"N Townsend","year":"2016","journal-title":"European Heart Journal"},{"key":"pone.0270689.ref002","doi-asserted-by":"crossref","first-page":"2444","DOI":"10.1093\/eurheartj\/ehy670","article-title":"Non-invasive imaging of the coronary arteries","volume":"40","author":"PD Adamson","year":"2019","journal-title":"European Heart Journal"},{"key":"pone.0270689.ref003","first-page":"2949","article-title":"2013 ESC guidelines on the management of stable coronary artery disease: the Task Force on the management of stable coronary artery disease of the European Society of Cardiology","author":"Task Force Members","year":"2013","journal-title":"European Heart Journal"},{"key":"pone.0270689.ref004","first-page":"e354","volume-title":"Circulation","author":"SD Fihn","year":"2012","edition":"11"},{"key":"pone.0270689.ref005","doi-asserted-by":"crossref","first-page":"1326","DOI":"10.2214\/AJR.07.2805","article-title":"Comparison of 3D free-breathing coronary MR angiography and 64-MDCT angiography for detection of coronary stenosis in patients with high calcium scores","volume":"189","author":"X Liu","year":"2007","journal-title":"AJR Am J Roentgenol. 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