Later the emphasis in the applied superconductivity research shifted to magnetic resonance imaging (MRI). This technique has become important in medical diagnostics. An experimental whole-body MRI unit was built in collaboration with the Technical Research Centre of Finland and Instrumentarium Ltd. The system was in routine clinical use at the Helsinki University Central Hospital from early 1982 to 1986.
Inspired by the success of our first superconducting magnet for medical imaging, a second solenoid, also suitable for whole-body MRI, was built during the years 1985 - 1988. The magnet produced a field of 1.5 T in an 80 cm room temperature bore. The field homogeneity is 10-7 inside a 20 cm diameter sample volume. The solenoid was made of NbTi/Cu filamentary composite superconducting wire, custom manufactured in Finland by Outokumpu Ltd and tested in our Laboratory. The magnet was designed for use in MRI studies on a living human being, using nuclei other than protons, for example 31P. The finished magnet met all its design specifications but, unfortunately, the development of the apparatus into a complete MRI system was halted by our sponsors.
We have constructed several highly successful multi-SQUID instruments for MEG studies. To utilize our accumulated know-how, a commercial company, Neuromag Ltd, was founded in 1989 for further development of multiSQUID magnetometers; an instrument covering the whole head, with 122 SQUIDs, became available in the summer of 1992. The prototype remains in the Low Temperature Laboratory as a research tool. For the moment, Neuromag Ltd is still operating within the premises of the LTL. The Company is funded by Instrumentarium Ltd, by SITRA, and by TEKES. For us, this project is a new type of collaboration with industry, aiming at efficient use of our existing know-how in the field of cryogenics and magnetometer technology.
An important facility in the LTL is the machine shop. Most of our cryostats, for example, have been constructed by our own technicians. The spin muon collaboration at CERN is a recent example in the utilization of our cryogenic skills.
Contributions of Matti Hämäläinen and Jukka Knuutila were important during the preparation of this Triennial Report.
July 1, 1993
