title: BabyMEG: A whole-head pediatric magnetoencephalography system for human brain development research.
abstract: We developed a 375-channel, whole-head magnetoencephalography (MEG) system ("BabyMEG") for studying the electrophysiological development of human brain during the first years of life. The helmet accommodates heads up to 95% of 36-month old boys in the USA. The unique two-layer sensor array consists of: (1) 270 magnetometers (10 mm diameter, ∼15 mm coil-to-coil spacing) in the inner layer, (2) thirty-five three-axis magnetometers (20 mm × 20 mm) in the outer layer 4 cm away from the inner layer. Additionally, there are three three-axis reference magnetometers. With the help of a remotely operated position adjustment mechanism, the sensor array can be positioned to provide a uniform short spacing (mean 8.5 mm) between the sensor array and room temperature surface of the dewar. The sensors are connected to superconducting quantum interference devices (SQUIDs) operating at 4.2 K with median sensitivity levels of 7.5 fT/√Hz for the inner and 4 fT/√Hz for the outer layer sensors. SQUID outputs are digitized by a 24-bit acquisition system. A closed-cycle helium recycler provides maintenance-free continuous operation, eliminating the need for helium, with no interruption needed during MEG measurements. BabyMEG with the recycler has been fully operational from March, 2015. Ongoing spontaneous brain activity can be monitored in real time without interference from external magnetic noise sources including the recycler, using a combination of a lightly shielded two-layer magnetically shielded room, an external active shielding, a signal-space projection method, and a synthetic gradiometer approach. Evoked responses in the cortex can be clearly detected without averaging. These new design features and capabilities represent several advances in MEG, increasing the utility of this technique in basic neuroscience as well as in clinical research and patient studies.
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Yoshio
authors: Y
authors: Okada
authors: Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
authors: Matti
authors: M
authors: Hämäläinen
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Kevin
authors: K
authors: Pratt
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Anthony
authors: A
authors: Mascarenas
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Paul
authors: P
authors: Miller
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Menglai
authors: M
authors: Han
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Jose
authors: J
authors: Robles
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Anders
authors: A
authors: Cavallini
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Bill
authors: B
authors: Power
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Kosal
authors: K
authors: Sieng
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Limin
authors: L
authors: Sun
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Seok
authors: S
authors: Lew
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Chiran
authors: C
authors: Doshi
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Banu
authors: B
authors: Ahtam
authors: Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 2, 98693 Ilmenau, Germany.
authors: Christoph
authors: C
authors: Dinh
authors: Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 2, 98693 Ilmenau, Germany.
authors: Lorenz
authors: L
authors: Esch
authors: Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors: Ellen
authors: E
authors: Grant
authors: Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
authors: Aapo
authors: A
authors: Nummenmaa
authors: Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA.
authors: Douglas
authors: D
authors: Paulson
mesh_terms: D001921:Brain / Q000254:growth & development / Q000502:physiology*; D002675:Child, Preschool; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation / Q000379:methods; D008297:Male; D012815:Signal Processing, Computer-Assisted