Purpose or Case Report: To compare how 3D MRI measurements of physeal cartilage volume, and DTI measurements (tract volume and length) correlate with growth parameters and detect differences in growth between patients treated with cis-retinoic acid and controls.

Methods & Materials: We calculated and compared physeal cartilage volumes from 3D MR images and physeal/metaphyseal DTI tract volumes and lengths from tractographic images in 20 neuroblastoma survivors treated with cis-retinoic acid and 20 age- and sex-matched controls. We correlated metrics with height percentile and annualized growth rate, correcting results for sex and age.

Results: DTI tract volumes had the highest correlation with height percentile (r= 0.74) followed by tract length (r=0.53) and 3D-Volume (r=0.40) (all p<0.02). Only tract volumes and lengths correlated with annualized growth velocity. Patients showed significantly smaller tract volumes (8.00cc vs. 13.71 cc, p<0.01) and shorter tract lengths (5.92 mm vs 6.99 mm, p=0.03) than controls, but no significant difference (4.51 cc vs 4.85 cc) on 3D MRI volumes. The 10 patients with lowest height percentiles had smaller tract volumes (5.07 cc vs. 10.93 cc, p<0.01), but not significantly different 3D MRI volumes. Tract volume was the best predictor of the effect of cis-retinoic acid with an accuracy of 75%.

Conclusions: DTI tract volume of the physis/metaphysis can predict abnormal growth better than physeal cartilage volumetric measurement and correlates best with height percentile and growth velocity.