Study type: Medical/biological study (experimental study)

A large-scale study on subjective perception of discomfort during 7 and 1.5 T MRI examinations med./bio.

By: Heilmaier C, Theysohn JM, Maderwald S, Kraff O, Ladd ME, Ladd SC
Published in: Bioelectromagnetics 2011; 32 (8): 610-619
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Aim of study (acc. to author)

A study on subjective perception has been carried out in order to gain further insight into subjective discomfort and sensations experienced during 7 T magnetic resonance imaging.

Background/further details

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.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: continuous for 37.1, 67.1, 68.5, 72.3, 78.2 min

General information

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

Exposure 1

Main characteristics
Frequency
Type
Exposure duration continuous for 37.1, 67.1, 68.5, 72.3, 78.2 min
Exposure setup
Exposure source
  • 1 whole body MRI scanner with 7 T, 4 whole body MRI scanner with 1.5 T
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
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 T - - - -
magnetic flux density 7 T - - - -
Additional parameter details

maximum gradient slew rate: 220 mT/m/ms maximum gradient: 45 mT/m

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

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.

Study character:

Study funded by

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