Fig. 3. Quantitative querying of three-dimensional reconstructions. By selecting different isovalues, specific structures of interest can be imaged three-dimensionally (refer to Materials and methods). In A, the 4.2 mm length of reconstructed control spinal cord is shown containing the entire region of damaged spinal cord, including cysts and lesioned parenchyma. The three-dimensional visualization algorithm also allowed the surface area and volume of this structure to be determined. The shape of the segment is compacted because of compression injury, although the flattened dorsal and ventral surfaces are artifacts arising from the loss of a few histological sections during sectioning as explained in Fig. 1 and in Materials and methods. In B, the intact and damaged parenchyma of the spinal cord segment are shown without the cystic cavitations, which could be imaged separately (by isovalue selection) and deleted from the overall reconstruction. Note the presence of a large cyst extending from the center of the rostral end of the segment (facing the viewer) as a pocket within the spinal cord. The surface area and volume of the cysts were easily calculated by subtracting numerical values obtained from this reconstruction (B) from those obtained from the section shown in A. (C) The intact spinal cord parenchyma, which was also evaluated quantitatively. Note that most of the spared parenchyma is found at the periphery of the spinal segment. Numerical values derived from this reconstruction (C) were subtracted from those for B to give the surface area and volume of the lesion. The cylindrical icon gives the relative orientation of the three-dimensional segment; gray is the rostral end and black is the caudal end. Scale bar (for A–C), 1 mm.
