Four-dimensional real-time cine images of wrist joint kinematics using dual source CT with minimal time increment scanning

Abstract

Purpose: To validate the feasibility of real time kinematography with four-dimensional (4D) dynamic functional wrist joint imaging using dual source CT.

Materials and methods: Two healthy volunteers performed radioulnar deviation and pronation- supination wrist motions for 10 s and 4 s per cycle in a dual source CT scanner. Scan and reconstruction protocols were set to optimize temporal resolution. Cine images of the reconstructed carpal bone of the moving wrist were recorded. The quality of the images and radiation dosage were evaluated.

Results: The 4D cine images obtained during 4 s and 10 s of radioulnar motion showed a smooth stream of movement with good quality and little noise or artifact. Images from the pronation-supination motion showed noise with a masked surface contour. The temporal resolution was optimized at 0.28 s.

Conclusion: Using dual source CT, 4D cine images of in vivo kinematics of wrist joint movement were obtained and found to have a shorter scan time, improved temporal resolution and lower radiation dosages compared with those previously reported.

Keywords: Dual source; carpal kinematics; computed tomography; dynamic imaging; four dimensional.

Fig. 1

Optimized time increment for minimum temporal resolution. Time increment is defined as the time interval from the scan starting point of one series to that of the next series; in other words, the time gap between frames of four-dimensional motion images. Two examples of 1 s (A) and 0.30 s (B) time increments are shown here. The temporal resolution (0.28 s) is depicted as a square in the upper row and the time increment is depicted as an arrow in the lower row. The number of arrows is equal to the number of frames in the motion image. (A) With a 1 s time increment, fewer frames were obtained in the fixed scan time, and the data scanned during the remaining 0.72 s (0.28 s subtracted from 1 s) were not collected. (B) With a 0.30 s time increment, which is the closest value to the temporal resolution (0.28 s), more frames were obtained in the fixed scan time and the wasted data were only that scanned during 0.02 s (0.28 s subtracted from 0.30 s).

Fig. 2

Cine images of 10 s of radioulnar deviations per cycle from a 26-year-old healthy female volunteer: Coronal view (A) and sagittal view (B). Individual carpal bones are differentiated and their interactions are identified. Translocations of proximal carpal bones to the radial side and distal carpal bones to the ulnar side are shown in the coronal view. Multiplanar movement (extension) of the scaphoid along with radioulnar deviation is clearly depicted in the sagittal view.

Fig. 3

Cine images of 10 s of wrist pronation-supination per cycle from a 27-year-old healthy female volunteer. Carpal bones and their interaction are depicted, but the image quality is lower than that of 10 s of radioulnar deviation per cycle due to motion artifact.

Fig. 4

Cine images of 4 s of radioulnar deviation (A) and pronation-supination (B) per cycle from a 27-year-old healthy female volunteer. With 4 s of radioulnar deviation per cycle, the margin and shape of the individual carpal bones are well visualized. The carpal bones are not fully covered in the 4 s radioulnar deviation images due to unintended forearm movement accompanying wrist movement, which is partially to reason that isolated wrist movement is more difficult during 4 s compared to 10 s. Though the pronation-supination images are lower quality than the radioulnar deviation images due to motion artifact, and the margin and shape of the carpal bones are blurred, the carpal bone movements are still depicted.