16.4T MRI of nephrectomy sample

Tissue samples were obtained from whole kidney post-nephrectomy without flushing the blood, fixed in formalin for 24 h and washed with saline for 3 d at 4°C prior to scanning.

Samples were scanned at room temperature using a Bruker Biospec 16.4 T MRI at the Centre for Advanced Imaging, The University of Queensland. This scanner is equipped with a Micro2.5 gradient (1.5 T/m at 60 A). Microimaging coils appropriate to the size of the samples were used, these included a 15×30 mm surface coil, a 15 mm and a 10 mm volume coil. Samples were either placed in saline or wrapped with paraffin film to minimise air artefacts. MRI was performed using a 3D T1/T2*-weighted gradient echo (GRE) sequence with repetition time TR = 150 ms, echo time TE = 6.2 ms, flip angle 60°.

Typically, the field-of-view was ~2.4×1.2×1.2 cm with the matrix sizes set to produce images at 30 μm 3D isotropic resolutions. The acquisition times were approximately 27 h (number of excitations (NEX) = 4). A sine windowing function was applied to the K-space data prior to the Fourier transform to reduce the noise in the 30 μm images.