Multiparametric MRI of Canine Prostate

In order to visualize the fine structure of the ultrasound lesions,
ex vivo canine prostate samples were imaged with a 9.4
Tesla Bruker BioSpec 33-cm horizontal bore scanner with a Bruker 72-mm birdcage
volume coil (Billerica, MA). Samples were submerged in Fluorinert (3M Co., St.
Paul, MN) and oriented to approximately replicate the in vivoorientation for the supine canines. Imaging protocols were tested on a phantom
prior to prostate imaging. Fast low-angle shot (FLASH) tri-pilot images were
acquired in three orthogonal planes to verify correct positioning of the sample
and determine angulation of axial slices for subsequent scans. T₁W
and T₂W images were acquired, and sequences for T₁,
T₂, and ADC mapping were performed as outlined in Table 2. ADC maps were computed from
diffusion-weighted images by fitting to an exponential decay as described
above.³⁷ T₁maps were computed from variable-TR rapid acquisition with refocused echoes (VTR
RARE) images by fitting each voxel magnitude in a least squares sense to an
exponential recovery.^{43 (link)}Similarly, T₂ maps were computed from multi-slice mutli-echo (MSME)
images by fitting each voxel magnitude in a least squares sense to an
exponential decay.^{44 (link)}