Diffraction-Enhanced Computed Tomographic Imaging of Growing Piglet Joints by Using a Synchrotron Light Source

Abstract

The objective of this project was to develop and test a new technology for imaging growing joints by means of diffraction-enhanced imaging (DEI) combined with CT and using a synchrotron radiation source. DEI-CT images of an explanted 4-wk-old piglet stifle joint were acquired by using a 40-keV beam. The series of scanned slices was later 'stitched' together, forming a 3D dataset. High-resolution DEI-CT images demonstrated fine detail within all joint structures and tissues. Striking detail of vasculature traversing between bone and cartilage, a characteristic of growing but not mature joints, was demonstrated. This report documents for the first time that DEI combined with CT and a synchrotron radiation source can generate more detailed images of intact, growing joints than can currently available conventional imaging modalities.

Figure 1.

(A) Axial slice of a DEI-CT refraction dataset through the femoral and tibial cartilage of a 4-wk-old porcine stifle joint. (B) Anatomic specimen, with soft tissue removed, showing the approximate orientation of the bones of the joint when imaged by DEI-CT. The vertical arrows indicate the imaging direction. (C) A lateral view of the disarticulated bones shown for orientation. The dashed box represents the approximate DEI-CT field of view. The horizontal arrow indicates the imaging direction. Dimensions, 5625 × 4219 pixels; resolution, 300 dpi.

Figure 2.

Z-projection through 20 axial slices of a DEI-CT refraction dataset through the femoral and tibial cartilage of a 4-wk-old porcine stifle joint, demonstrating the vascularity of the cartilage. Dimensions, 1704 × 1362 pixels; resolution, 300 dpi.

Figure 3.

(A) Sagittal sections approximately midjoint of DEI-CT scans of a 4-wk-old porcine stifle joint (A1; magnification, A2). The tibial ossification center is visible at the bottom of each image. Vasculature is visible within the cartilage. White arrows indicate vessels traversing through trabecular bone and bone cortex into the cartilage. (B) Sagittal z-projection of a 4-wk-old porcine stifle joint at 37.4 µm, showing vasculature in the femoral cartilage (arrows). (C) A sum-projection image shows anterior and posterior cruciate ligaments at the center of the joint. Dimensions, 2400 × 1800 pixels; resolution, 300 dpi.

Figure 4.

Comparative nonDEI-CT images of a 4-wk-old piglet stifle joint. (A) Conventional radiography, lateral view. (B) CT, saggital view. (C) MRI, saggital view. Arrows indicate cartilage. (D) MRI, coronal view with joint partially flexed to reveal femoral and tibial cartilaginous surfaces. Arrows indicate cartilage. (E) DEI without CT, lateral view. Arrows indicate cartilage surface. Dimensions, 2716 × 726 pixels; resolution, 300 dpi.

Figure 5.

Damage to cartilage was iatrogenically induced by inserting 2 acupuncture needles (diameter, 200 µm) and scanning the specimen (A) with the needles (white arrows) in place and then (B) with the needles removed. One needle (arrow 1) was inserted end-on into the articular cartilage, whereas the other needle (arrow 2) was inserted transversely through the cartilage surface. Both the needles themselves (A) and the needle tracks after needle removal (B) are clearly visible. Dimensions, 1872 × 1404 pixels; resolution, 300 dpi.