Computed tomography method for characterising the zebrafish spine.

Background: The zebrafish is widely used in research due in part to its readily manipulable genome. Zebrafish models of spinal deformities including scoliosis were developed recently. However, the methods used to assess the spine in these models vary across studies. The primary objective of this study was to investigate the feasibility and modalities of local and regional spine structure evaluation by micro-CT in the normal zebrafish. The secondary objectives were to assess the feasibility of spinal angle measurements in normal zebrafish subjected to external stresses designed to mimic spinal deformities, to determine normal angle values in the coronal and sagittal planes, and to detail the micro-CT features of the zebrafish spine.

Hypothesis: Micro-CT is an effective and reproducible tool for determining orthopaedic parameters to characterise the zebrafish spine.

Material And Methods: Two observers conducted preliminary analyses on 15 zebrafish including 12 adults (aged 18 months) and 3 juveniles (aged 12 weeks). For the analyses, 6 of the animals were placed in an artificial position to mimic a scoliosis spinal deformity. Micro-CT (Quantum FX Caliper™) was used with 59μm resolution and a 30-mm field of view. Image processing was with RadiAnt DICOM Viewer™ software.

Results: We defined several assessment planes on the 3D micro-CT reconstructions to measure orthopaedic parameters in the sagittal plane (thoracic and maximal kyphotic curves with their apices, length of the various spinal segments, and sagittal index) and coronal plane (Cobb angles, apices, end-vertebrae, coronal alignment, and side of the convexity). Mean thoracic kyphosis was 20.5°±5.0° in the adults and 8.7° in the juveniles. No curvature was apparent in the coronal plane in the zebrafish left in the neutral position. In the zebrafish with artificially induced curves, micro-CT was effective in determining the Cobb angles and apical vertebrae.

Discussion: This work defines a standardised micro-CT method for assessing the zebrafish spine. In addition, spinal parameter values that can be considered normal were determined, namely, less than 30° of thoracic kyphosis in the sagittal plane and less than 10° in the coronal plane. Our method was effective in assessing induced spinal deformities on micro-CT reconstructions. We hope it will prove of value in future studies of the zebrafish model.

Level Of Evidence: IV.