| Zugriffsnummer | 34423 |
| Dokumenttyp | Konferenzartikel |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | From real-time SAR assessment to temperature distributions in coronary stents at 7T |
| Autor(in); Institution |
Winter, L.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
Oberacker, E.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
Özerdem, C.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
Ji, Y.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
Knobelsdorff-Brenkenhoff, F. von; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
Weidemann, Gerd; 8.1, Medizinische Messtechnik, PTB-Berlin
Ittermann, Bernd; 8.1, Medizinische Messtechnik, PTB-Berlin
Seifert, Frank; 8.1, Medizinische Messtechnik, PTB-Berlin
Niendorf, Th.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, GERMANY
|
| Quelle/Jahr | ISMRM 23th Annual Meeting & Exhibition: 30 May – 5 June, 2015; Toronto, Canada:(2015), 1 S. |
| Availability | [CD-ROM] ; file name: 0304.pdf |
| ISSN | 1545-4428 |
| Verlag | Berkeley, Calif.: ISMRM |
| Konferenzangaben | 23th ISMRM Annual Meeting & Exhibition, Toronto, 30 May – 5 June, 2015, Canada |
| Zusammenfassung | The analytical approach proposed for real-time SAR assessment in coronary stents proved to be able to detect whether SAR obeyed the IEC limits. The deviation between simulations and measurements of absolute E-field values was -13% (no stent equivalent) and -25% (with a stent equivalent). The coronary stent induced -22% lower measured E-field peak values than a copper tube mimicking the stent, while our simulations indicated a difference of -25%. The deviation between fiber optic thermometry, MR thermometry and thermal simulations accounted for ΔT(1°C. Immediately after onset of RF power transmission the max temperature rise was found at the stent tip where SAR 1g levels were higher (264W/kg) than in slice I (117W/kg) of the phantom investigated. With ongoing RF power Deposition heat is dissipated from the stent tip to cooler (RF shielded) tissue regions inside the stent center due to high thermal conductivity of the stent (9.4WK-1 m-1) and tissue (0.53WK-1 m-1). After t)80s the temperature distribution in slice I dominated the max temperature . After RF power is switched off (e.g. during protocol preparation in an MRI session), stent temperatures decreased while temperatures in other regions remained constant . After 6min RF heating maximum temperature in slice I was )6°C above the temperature value at the stent, although SAR 1g in the stent was a factor of 2.3 higher than in the phantom. Our simulations show that blood flow reduces induced temperature in the stent . Here the transition point between a stent heating dominated regime and a surface heating dominated regime can be reached earlier for low residual flow levels. |
Zitierung
Winter, L., Oberacker, E., Özerdem, C., Ji, Y., Knobelsdorff-Brenkenhoff, F. V., Weidemann, G., Ittermann, B., Seifert, F., & Niendorf, T. (2015). From real-time SAR assessment to temperature distributions in coronary stents at 7T. 23th ISMRM Annual Meeting & Exhibition, Toronto, 30 May – 5 June, 2015, Canada.