High-field magnetic resonance imaging in multiple sclerosis

In many case the clinical symptoms of Multiple Sclerosis do not comply with
results from MR images. Solving this so called clinico-radiological paradox is
one of the most important research goals of MS research. De reason for this
paradox might be found in the lack of sensitivity and/or resolution of the MR
images.

The signal to noise ratio of 1.5 Tesla scanners is not high enough to enhance
the spatial resolution of the images. Also lack of contrast is caused by a too
low signal to noise ratio. A higher main magnet field can solve these problems
for a large part. Therefore high field (3 Tesla, VUmc, Amsterdam) and ultra
high field (7 Tesla, UMC Utrecht) MR scanners will be used in this study.

Differences in magnetic properties of different tissue types (white matter,
gray matter etc.) are the reason for contrast in MR images. These differences
can be used to detect lesions. Unfortunately, the contrast is a relative
measure in qualitative MR imaging resulting in missing of diffuse lesions with
low contrast compared to healthy tissue. An absolute quantitative measure
increases the possibility to detect minute changes in tissue, which results in
an earlier and/or more reliable diagnosis.

The objective of this study is the visualisation of diffuse and focal lesion in
the brain in Multiple Sclerosis on higher main magnetic fields. Images from
1.5 Tesla MR scanners will be compared with images acquired at 3 Tesla and
images made on 3 Tesla will be compared with images made at 7 Tesla. Besides
qualitative imaging, also quantitative imaging will be performed at 1.5 and 3
Tesla. At 7 Tesla the focus will be on the detection limit of brain lesions for
spatial resolution and contrast.

Qualitative imaging consists of T1, T2 and Pd weighted images, FLAIR, DIR, SWI
and diffusion. The quantitative images consist of T1 and T2 relaxation images
and diffusioin (ADC, FA and DTI). This results in insight in accurate
information on the nature of lesions. Als the onset of very small lesions can
be studied this way.

The scan protocols are divided into qualitative and quantitative groups. Half
of the volunteers will be scanned on 1.5 and 3 Tesla. They will undergo a
combined qualitative and quantitative protocol. The other volunteers will be
scanned at 3 and 7 Tesla. This group will undergo a quantitative and
qualitative protocol at 3 Tesla and only a qualitative protocol at 7 Tesla.

All images will be read for quality (eg. artefacts) and also for the number of
visible lesions (diffuse and focal). The quantitative images will be used for
analysis of lesion characteristics. Also the results obtained on different
scanners will be compared.

The burden for the volunteers is considered low. The noise made by the scanner
will as far as possible be damped by ear protection. Next to the noise the
volunteer is only asked to lie still for a maximum duration of one hour. During
the session several small breaks will be planned to ask for the volunteers
condition and to allow coughing eg. If necessary the scanning can be stopped
inmediately by the researcher or the patient (emergency button). The volunteer
can also listen to music of its choice.

No damage caused by MRI is known as long as normal procedures are followed. The
research is of no influence on the treatment of the patient even if the
volunteer decides to cancel its cooperation during the study.