Seraphin H. Unterberger et al. Morphological and Tissue Characterization with 3D Reconstruction of a 350-Year-Old Austrian Ardea purpurea Glacier Mummy Biology.
January 11, 2023
How Analyze was Used
“Micro-CT measurements were performed on a vivaCt40 and an XtremeCT II (ScancoMedical AG, Brüttisellen, Switzerland). Due to the geometrical dimensions, the corpus of the mummy was scanned only in the XtremeCT II. The mummy’s skull was further analyzed in the vivaCT40 due to its higher resolution. The settings for the XtremeCT II experiments were a 30.5 µm isotropic voxel size with a 68 kV, 1470 µA tube setting and 650 ms exposure time. The image matrix was 4096 × 4096, with a 16-bit grey-value resolution. The settings for the micro-CT experiment were a 10.5 µm isotropic voxel size with a 70 kV, 114 µA tube setting, 6500 ms exposure time, 1000 projections, and 2048 samples. The image matrix was 2048 × 2048 with a 16-bit grey-value resolution. The micro-CT data were evaluated by an experienced radiologist and summarized. The reconstructions were carried out with Analyze 14.0 (Analyze Direct Inc., Overland Park, KS, USA) software.
The following two-dimensional display formats were used for the reconstructions:
Planar CT slice images: reconstructed CT slice images along axial, sagittal, or coronal planes.
Multi-planar reconstruction: reconstructed CT slice images along planes of freely selectable position and angle.
Curved planar reconstruction: reconstructed CT slice images along planes of arbitrary orientation.
Various three-dimensional reconstructions were also used:
Maximum intensity projection: the voxel with the highest intensity is displayed along a specific projection through the volume dataset.
Surface Rendering: according to a defined mean value, the surface is rendered along a certain projection of the volume data set.
Volume Rendering: assignment of a color value to a voxel according to its X-ray density. It is then possible to make certain regions transparent.
Segmentation: semi-automatic segmentation tools such as Threshold Volume, Region Grow, and Object Extractor were used to segment the calcifications and internal organs. The procedure consists of selecting a pixel within an area called a seed. Neighboring pixels of similar density are automatically added or connected. A density threshold is chosen to capture the total volume in the pmCT layer. This process is repeated for each layer, and the total volume is automatically added.”
Magnetic resonance imaging, Micro-computed tomography, Radiocarbon dating, DNA barcoding
Medical University of Innsbruck, Innsbruck, Austria