Magnetic resonance and diffusion tensor imaging of the adolescent rabbit growth plate of the knee

Abstract

To assess the ability of MRI-DTI to evaluate growth plate morphology and activity compared with that of histomorphometry and micro-CT in rabbits. Methods:The hind limbs of female rabbits aged 16, 20, and 24 wk (n = 4 per age group) were studied using a 9.4T MRI scanner with a multi-gradient echo 3D sequence and DTI in 14 directions (b-value = 984 s/mm 2 ). After MRI, the right and left hind limb were processed for histological analysis and micro-CT, respectively. The Wilcoxon signed-rank test was used to evaluate the height and volume of the growth plate. Intraclass correlation and Pearson correlation coefficient were used to evaluate the association between DTI metrics and age. Results:The growth plate height and volume were similar for all modalities at each time point and age. Age was correlated with all tractography and DTI metrics in both the femur and tibia. A correlation was also observed between all the metrics at both sites. Tract number and volume declined with age; however, tract length did not show any changes. The fractional anisotropy color map showed lateral diffusion centrally in the growth plate and perpendicular diffusion in the hypertrophic zone, as verified by histology and micro-CT. Conclusion: MRI-DTI may be useful for evaluating the growth plates.

Applications of Diffusion‐Weighted MRI to the Musculoskeletal System

“…MD, a measure of cartilage matrix integrity, has been less useful than tractography parameters. In rabbits, DTI tractography correlates with the columnar architecture of the physis and metaphysis seen by histology and micro‐CT 23,24 …”

“…Most physeal DTI has been performed at 3 T. Although the imaging parameters have varied, most studies have used 14 to 20 directions, a b ‐value of 600 s/mm 2 , and a tractography reconstruction including an angular threshold of 40° with a FA value of 0.15 15,18–23 . Increasing the angular resolution (greater number of directions) and the b ‐value leads to larger tracts, but this requires larger scan times to maintain the SNR.…”

“…3 and 4). 15,[18][19][20][21][22][23][24][25] DTI depicts the organization and orientation of the tracts, provides quantitative data about their volume and length, and measures FA, an indicator of the parallel organization of the tracts. MD, a measure of cartilage matrix integrity, has been less useful than tractography parameters.…”

“…MD, a measure of cartilage matrix integrity, has been less useful than tractography parameters. In rabbits, DTI tractography correlates with the columnar architecture of the physis and metaphysis seen by histology and micro-CT. 23,24 Most physeal DTI has been performed at 3 T. Although the imaging parameters have varied, most studies have used 14 to 20 directions, a b-value of 600 s/mm 2 , and a tractography reconstruction including an angular threshold of 40 with a FA value of 0.15. 15,[18][19][20][21][22][23] Increasing the angular resolution (greater number of directions) and the b-value leads to larger tracts, but this requires larger scan times to maintain the SNR.…”

Impact of Deep Learning Denoising Algorithm on Diffusion Tensor Imaging of the Growth Plate on Different Spatial Resolutions

“…The use of DTI in the physeal–metaphyseal complex for prediction of pediatric growth has been studied for approximately 10 years [ 7 ]. Characterization of columns of cartilage and newly formed bone in the physis and adjacent metaphysis through tractography has proven useful for the determination of height gain and the evaluation of growth failure in pediatric subjects [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Tractography is the result of tensor estimation inside each voxel; the tensor depicts the main direction of unrestricted water diffusion inside the columns running perpendicular to the growth plate [ 2 , 7 ].…”