Feasibility of in ovo diffusion tractography in the chick embryo using a dual‐cooling technique

PURPOSE: To evaluate the capability of a dual-cooling technique in suppressing motion artifact and to evaluate the feasibility of the noninvasive muscle fibers tracking using DTI during chick embryonic development. MATERIALS AND METHODS: Fifteen eggs were divided into three groups of 5 eggs each (one group for each imaging sequence), and eggs were imaged every 48 h from incubation day 4; embryos were imaged in ovo using three sequences of varying duration (T1, T2, and DTI). For each sequence, three preprocessing methods were used: no-cooling (NC), single-cooling (SC), and dual-cooling (DC). Two independent observers assessed images for motion artifact. The results of different preprocessing methods used for each sequence were compared by the χ(2) test. The Cohen kappa test was used to assess the interobserver variability. RESULTS: For T1 imaging, motion artifact was adequately suppressed by both SC and DC methods (χ(2) test; P > 0.05). For T2 imaging, motion artifact was also sufficiently suppressed by both SC and DC methods (χ(2) test; P > 0.05) except incubation day 19 (χ(2) test; P < 0.001). For DTI, motion artifact was less with DC than SC after 8 days (χ(2) test; P < 0.05). Hindlimb muscle fibers of chick embryo could be serially evaluated with DTI from 8 days using dual-cooling technique. CONCLUSION: The dual-cooling technique enables DTI of chick embryo in ovo with minimal motion artifact, which permits muscle fiber tracking by DTI during chick embryonic development possible, and can improve the imaging quality of conventional MRI with long duration and those sensitive to motion.