MRI imaging versus histologic volumetric estimation of residual injection laryngoplasty material

Objectives: To examine the degree of agreement between MRI and histologically generated volumetric measurements of residual injection laryngoplasty material. Methods: Following left recurrent laryngeal nerve transection, rabbit vocal cords were injected with jellyfish collagen, Cymetra®, or Restylane®. Laryngeal tissue was harvested 4 or 12 weeks post injection followed by MRI imaging and histologic cross-sectioning. Two raters estimated the volume of remaining injection material in specimens within MRI and histologic axial cross sections. Wilcoxon signed rank tests were employed to detect gross differences between inter-rater measurements and between imaging modalities across time. Agreement between rater measurements and imaging (histology and MRI) was assessed using intra-class correlation coefficients. Results: Data was available from 16 rabbits sacrificed at 4 weeks (n = 8) and 12 weeks (n = 8). Inter-rater testing of MRI imaging revealed no significant differences (p >.05) between rater measurements across time points, and excellent agreement (0.93; 95% confidence interval 0.80–0.98) while histologically estimated volumes demonstrated a significant difference at 4 weeks (p <.05) and overall good agreement (0.89; 95% confidence interval 0.59–0.97). Comparison of MRI and histologically estimated volume measurements revealed significant differences at the 4-week time point (p <.05) but not at 12 weeks (p >.05). Overall, there is only moderate agreement between MRI and histology estimates (0.72; 95% confidence interval 0.22–0.90). Conclusions: MRI imaging demonstrates good reliability and similar estimates of volume to histologically estimated measurements of residual injection laryngoplasty material at time points clinically relevant for future injection laryngoplasty experiments. Level of Evidence: NA.