Image Data

The image data sets were obtained on a 1.5 T whole body MRI scanner (Siemens, Magnetom Vision). Four healthy male volunteers (aged 24-32 years) were examined in a prospective study employing a standardized MRI sequence protocol: T1 weighted MP-RAGE, T2 weighted and proton density (PD) weighted spin echo, and Inversion-Recovery (IR) sequences. The MRI acquisition parameters of each sequence are listed in Table 1.

A second essential preprocessing step is the anatomically correct alignment of the data sets obtained by the different MRI sequences. In general, it is sufficient to process the raw image data without further image registration, as the head of the scanned subject is kept in a constant position during the whole MRI acquisition protocol and a corresponding field of view (FOV) is applied in each of the four MRI sequences. Only the T1 weighted image data had to be resampled with respect to matrix size and slice position in order to match the parameters of the other MRI sequences (see Table 1). However, correct alignment may require additional preprocessing steps, if motion artifacts have to be corrected. This situation will be discussed in Section 6.1.

Figure 3 presents an example of corresponding images of the four different MRI acquisition techniques. The example shows one of 63 coronal cross-sections orthogonal to the anterior commissure-posterior commissure (AC-PC) line that were acquired according to a pilot plan shown in Fig. 4.

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