Scientific Concept of the National Cohort (status ... - Nationale Kohorte

A.3
A.3 Study design
the possible depth of examination. The arbitrary requirement to examine one subject in a
40-min examination time imposes a limitation on the amount of information that can be acquired.
Longer MRI examination times of 60–70 min, for example, which are well tolerated
by study subjects according to the experience at the SHIP site, will make it possible to additionally
cover the research interests of most groups. Such a program would not only result
in good comparability of the National Cohort data with other major studies in the field, but
also provide extra and innovative options that have not been addressed in any other study.
We expect a final decision on this issue in early 2011.
A further alternative is under evaluation: Instead of implementing four stationary MRI centers,
vendors are asked to calculate costs for mobile MRI centers, either as a truck-based
or a container-based solution. The advantage of mobile centers would be that MRI could
be performed at more than four study centers. However, costs would have to fit into the
financial budget.
MRI follow-up examination
Protocol: After performing baseline MRI examinations over a period of 5 years, follow-up
MRI examinations will be conducted in all subjects willing to participate. The follow-up scans
will similarly be performed over a period of 5 years. Identical technical equipment, technologist
staff, and a similar imaging protocol will be applied to ensure highest internal validity.
Thus, no adjustments will be made to the protocol detailed in the paragraph Proposed MRI
Imaging Protocol.
Also, there will be no update of software or hardware.
follow-up rate: Based on experience of the SHIP study and the Framingham Heart Study,
we anticipate that approximately 50% of subjects scanned at baseline will receive a repeat
MRI examination.
workflow: The study center will maintain all contact with the participants. Subjects will
be informed that a repeat MRI exam is scheduled after a follow-up period of 5 years (±2
months) when consent is obtained for the baseline scan. All subjects who were scanned at
baseline will receive a written invitation for the repeat exam which specifically highlights the
importance and value of the follow-up examination. They are invited to individually schedule
their examination. A follow-up phone call will be made to ensure that the participant received
the written invitation.
An approximate follow-up response of 50% would imply that, in an average study center
with 20,000 participants, an imaging site would have an overcapacity with respect to the
number of study subjects who accept to be examined. In addition, if only 20% of the more
intensively characterized participants are offered MRI examinations, this would result in a
total of only 3,000 participants (50% of 6,000 participants). Thus, an additional proportion of
approximately 30–50% of participants in the Level 1 examination program can be offered to
take part in the MRI subproject.
Data transfer and archive
To ensure data safety and availability of all images for the centralized first-line reading in the
centralized reading core, all acquired data will be stored two-fold: (1) All data will be sent
to the reading core at the competence center on imaging to perform the first-line reading;
and, (2) as detailed in Sect. A.4.2, all images will be long-term archived at (at least) one of
the two national Integration Centers for the National Cohort. The preferred way of organizing
the data transfer is to send the images from the imaging site to the integration centers,
112