Abstract: The application of the cryogenically cooled resonator enables rapid DTI acquisitions as basis for cohort studies in mice.
Hans-Peter Müller1 , Ina Vernikouskaya2,3, Albert C. Ludolph1 , Jan Kassubek1 , Detlef Stiller4, Volker Rasche2,3
1 Department of Neurology, University Hospital Ulm, Ulm, Germany
2 Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany
3 Small Animal MRI, Medical Faculty, University of Ulm, Ulm, Germany
4 Target Discovery Research, Boehringer Ingelheim Pharma GmbH&Co. KG, Biberach, Germany5 Aggarwal M, Mori S, Shimogori T, Blackshaw S, Zhang J (2010) Threedimensional diffusion tensor microimaging for anatomical characterization of the mouse brain. Magn Reson Med 64: 249-261
Introduction: in vivo high resolution diffusion tensor imaging (DTI) of the mouse brain has proven promising application for a variety of pathologies. Its application to large cohort studies, however, is often limited by the intrinsic low signal to noise ratio (SNR) causing long acquisition times. Cryogenically cooled resonators (CCR) have demonstrated the potential for significantly increasing SNR and appear attractive for reducing scan times in DTI imaging thus enabling cohort studies. This contribution describes the DTI acquisition optimization using CCRs and presents the outcome of an initial cohort study at the group level to β-amyloid precursor protein (APP) transgenic mice.
Methods: A DTI sequence providing 156² x 250 µm³ spatial resolution with 30 diffusion encoding directions was optimized for using CCR at ultrahigh field (11.7 T), resulting in a total acquisition time of 35 minutes. The quality was directly compared with a standardized 110 minutes acquisition protocol published earlier. Fractional anisotropy (FA) and fiber tracking (FT) results including quantitative tractwise fractional anisotropy statistics (TFAS) were qualitatively and quantitatively compared. The optimized sequence was then applied to 5 wild type and 7 APP transgenic (tg2576) mice for investigation of its potential for cohort studies. Fractional anisotropy (FA) maps were statistically compared by whole brain-based spatial statistics (WBSS) at the group level vs. wild type controls.