title: Potential Heating Effect in the Gravid Uterus by Using 3-T MR Imaging Protocols: Experimental Study in Miniature Pigs.
abstract: Purpose To determine the changes in temperature within the gravid miniature pig uterus during magnetic resonance (MR) imaging at 3 T. Materials and Methods The study received ethics committee approval for animal experimentation. Fiber-optic temperature sensors were inserted into the fetal brain, abdomen, bladder, and amniotic fluid of miniature pigs (second trimester, n = 2; third trimester, n = 2). In the first trimester (n = 2), the sensors were inserted only into the amniotic fluid (three sacs per miniature pig, for a total of six sacs). Imaging was performed with a 3-T MR imager by using different imaging protocols in a random order for animal, each lasting approximately 15 minutes. The first regimen consisted of common sequences used for human fetal MR examination, including normal specific absorption rate (SAR). The second regimen consisted of five low-SAR sequences, for which three gradient-echo sequences were interspersed with two diffusion-weighted imaging series. Finally, a high-SAR regimen maximized the radiofrequency energy deposition (constrained by the 2-W per kilogram of body weight SAR limitations) by using five single-shot turbo spin-echo sequences. Differences in temperature increases between the three regimens and between the three trimesters were evaluated by using one-way analysis of variance. The maximum cumulative temperature increase over 1 hour was also evaluated. Results Low-SAR regimens resulted in the lowest temperature increase (mean ± standard deviation, -0.03°C ± 0.20), normal regimens resulted in an intermediate increase (0.31°C ± 0.21), and high-SAR regimens resulted in the highest increase (0.56°C ± 0.20) (P < .0001). Mean temperature increase in the third trimester was 0.38°C ± 0.27, with no significant differences compared with the first (0.23°C ± 0.27) and second (0.25°C ± 0.32) trimesters (P = .07). The cumulative temperature increase over 1-hour imaging time with high SAR can reach 2.5°C. Conclusion In pregnant miniature pigs, the use of 3-T magnets for diagnostic MR imaging with normal SAR regimens does not lead to temperature increases above 1°C if imaging time is kept below 30 minutes. Longer imaging time, especially with high-SAR regimens, can lead to an increase of 2.5°C. (©) RSNA, 2015 Online supplemental material is available for this article.
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Mieke M
authors.initials: MM
authors.lastname: Cannie
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Frederik
authors.initials: F
authors.lastname: De Keyzer
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Sigrid
authors.initials: S
authors.lastname: Van Laere
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Astrid
authors.initials: A
authors.lastname: Leus
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Johan
authors.initials: J
authors.lastname: de Mey
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Catherine
authors.initials: C
authors.lastname: Fourneau
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Filip
authors.initials: F
authors.lastname: De Ridder
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Toon
authors.initials: T
authors.lastname: Van Cauteren
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Inneke
authors.initials: I
authors.lastname: Willekens
authors.affiliation: From the Departments of Radiology (M.M.C.), Fetopathology (C.F.), and Obstetrics and Gynecology (J.C.J.), University Hospital Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, 1020 Brussels, Belgium; Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium (F.D.K.); Department of Radiology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium (M.M.C., A.L., J.d.M., F.D.R., T.V.C., I.W.); and Animalarium, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium (S.V.L.).
authors.forename: Jacques C
authors.initials: JC
authors.lastname: Jani
mesh_terms: D000818:Animals; D005260:Female; D006358:Hot Temperature; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D013552:Swine; D013556:Swine, Miniature; D014599:Uterus / Q000000981:diagnostic imaging / Q000502:physiology*