<p>Background Accurate and precise methods to predict growth remain lacking. Diffusion tensor imaging (DTI) depicts the columnar structure of the physis and metaphyseal spongiosa and provides measures of tract volume and length that may help predict growth. Purpose To validate physeal DTI metrics as predictors of height velocity (1-year height gain from time of MRI examination) and total height gain (height gain from time of MRI examination until growth stops) and compare the prediction accuracy with bone age-based models. Materials and Methods Femoral DTI studies ( values = 0 and 600 sec/mm; directions = 20) of healthy children who underwent MRI of the knee between February 2012 and December 2016 were retrospectively analyzed. Children with height measured at MRI and either 1 year later (height velocity) or after growth cessation (total height gain, mean = 34 months from MRI) were included. Physeal DTI tract volume and length were correlated with height velocity and total height gain. Multilinear regression was used to assess the potential of DTI metrics in the prediction of both parameters. Bland-Altman plots were used to compare root mean square error (RMSE) and bias in height prediction using DTI versus bone age methods. Results Eighty-nine children (mean age, 13 years ± 3 [SD]; 47 boys) had height velocity measured, and 70 (mean age, 14 years ± 1; 36 girls) had total height gain measured. Tract volumes correlated with height velocity ( = 0.49) and total height gain ( = 0.46) ( &lt; .001 for both) after controlling for age and sex. Tract volume was the strongest predictor for height velocity and total height gain. An optimal multilinear model including tract volume improved prediction of height velocity ( = 0.63, RMSE = 1.7 cm) and total height gain ( = 0.59, RMSE = 1.8 cm) compared with bone age-based methods (height velocity: = 0.32, RMSE = 2.9 cm; total height gain: = 0.42, RMSE = 5.0 cm). Conclusion Models using tract volume derived from diffusion tensor imaging may perform better than bone age-based models in children for the prediction of height velocity and total height gain. © RSNA, 2022.</p>

<p><strong>BACKGROUND: </strong>Current methods to predict height and growth failure are imprecise. MRI measures of physeal cartilage are promising biomarkers for growth.</p>

<p><strong>PURPOSE: </strong>In the physis, to assess how 3D MRI volume measurements, and diffusion tensor imaging (DTI) measurements (tract volume and length) correlate with growth parameters and detect differences in growth. We compared patients exposed to cis-retinoic acid, which causes physeal damage and growth failure, with normal subjects.</p>

<p><strong>STUDY TYPE: </strong>Case-control.</p>

<p><strong>POPULATION: </strong>Twenty pediatric neuroblastoma survivors treated with cis-retinoic acid and 20 age- and sex-matched controls.</p>

<p><strong>FIELD STRENGTH/SEQUENCE: </strong>3T; DTI and 3D double-echo steady-state (DESS) sequences.</p>

<p><strong>ASSESSMENT: </strong>On distal femoral MR studies, physeal 3D volume and DTI tract measurements were calculated and compared to height.</p>

<p><strong>STATISTICAL TESTS: </strong>We used partial Spearman correlation, analysis of covariance, logistic regression, Wald test, and the intraclass correlation coefficient (ICC).</p>

<p><strong>RESULTS: </strong>The height percentile correlated most strongly with DTI tract volumes (r = 0.74), followed by mean tract length (r = 0.53) and 3D volume (r = 0.40) (all P &lt; 0.02). Only tract volumes and lengths correlated with annualized growth velocity. Relative to controls, patients showed smaller tract volumes (8.00 cc vs. 13.71 cc, P &lt; 0.01), shorter tract lengths (5.92 mm vs 6.99 mm, P = 0.03), and smaller ratios of 3D cartilage volume to tract length; but no difference (4.51 cc vs 4.85 cc) in 3D MRI volumes. The 10 patients with the lowest height percentiles had smaller tract volumes (5.07 cc vs. 10.93 cc, P &lt; 0.01), but not significantly different 3D MRI volumes. Tract volume is associated with abnormal growth, with an accuracy of 75%.</p>

<p><strong>DATA CONCLUSION: </strong>DTI tract volume of the physis/metaphysis predicts abnormal growth better than physeal cartilage volumetric measurement and correlates best with height percentile and growth velocity.</p>

<p><strong>EVIDENCE LEVEL: </strong>2 TECHNICAL EFFICACY: Stage 2.</p>