Of 573 subjects who underwent 7 T MRI, 166 were also examined at 1.5 T, providing a means of discriminating field-dependent discomfort. Subjects included many subjects with pathological conditions to simulate a patient population (n=323 patients). Scores were analyzed separately for examination phases, with and without table movement at each field strength.
For further information on the setup see also: Kraff O, Bitz AK, Kruszona S, Orzada S, Schaefer LC, Theysohn JM, Maderwald S, Ladd ME, Quick HH. 2009. An eight-channel phased array RF coil for spine MR imaging at 7 T. Invest Radiol 44:734-740
|Setup||3.4 m long whole body scanner with a bore diameter of 60 cm; subjects placed supine on the scanner table, 85 in "feet-first", 451 in "head-first" and 37 in "head first" and prone position; for some examinations a moveable scanner table was used, in other examinations the table was moved manually; MRI scanners were used in different modes|
The data revealed that 7 T MRI was, in general, judged more uncomfortable than 1.5 T. However, most subjects rated the effects as being non-critical. Significant differences were detected regarding vertigo and sweating between subjects positioned "head-first" and "feet-first" at 7 T (worse in "head-first") and between 7 and 1.5 T (worse at 7 T), with the effects being more pronounced in the moving compared to the stationary table position. The most unpleasant factor at 7 T was the extensive examination duration, while potentially field-dependent sensations were rated less bothersome.
In summary, the study indicates that although certain sensations increase at 7 T compared to 1.5 T, they are unlikely to hinder the use of 7 T MRI as a clinical diagnostic tool.