Imaging Biomarkers of the Physis: Cartilage Volume on MRI vs. Tract Volume and Length on Diffusion Tensor Imaging

Abstract

BackgroundCurrent methods to predict height and growth failure are imprecise. MRI measures of physeal cartilage are promising biomarkers for growth.PurposeIn 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.Study TypeCase–control.PopulationTwenty pediatric neuroblastoma survivors treated with cis‐retinoic acid and 20 age‐ and sex‐matched controls.Field Strength/Sequence3T; DTI and 3D double‐echo steady‐state (DESS) sequences.AssessmentOn distal femoral MR studies, physeal 3D volume and DTI tract measurements were calculated and compared to height.Statistical TestsWe used partial Spearman correlation, analysis of covariance, logistic regression, Wald test, and the intraclass correlation coefficient (ICC).ResultsThe 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 < 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 < 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 < 0.01), but not significantly different 3D MRI volumes. Tract volume is associated with abnormal growth, with an accuracy of 75%.Data ConclusionDTI tract volume of the physis/metaphysis predicts abnormal growth better than physeal cartilage volumetric measurement and correlates best with height percentile and growth velocity.Evidence Level2Technical EfficacyStage 2 J. Magn. Reson. Imaging 2020;52:544–551.

Applications of Diffusion‐Weighted MRI to the Musculoskeletal System

“…In 20 patients with abnormal physes from cis‐retinoic acid administration, tract volume was much smaller compared to age‐matched controls. In these subjects, FA decreased relative to controls 19,21 …”

“…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.…”

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

“…17 However, few studies have addressed this hypothesis in animals [18][19][20] or humans. 17,[21][22][23] Methods that allow visualization of growth plate cartilage with improved resolution would be clinically useful in the assessment of congenital and acquired disorders, such as skeletal dysplasia's, infectious and inflammatory diseases, and Salter-Harris fractures. 24 Potentially, they can also be used in bone age assessments and adult height prediction models.…”

“… 17 However, few studies have addressed this hypothesis in animals 18 , 19 , 20 or humans. 17 , 21 , 22 , 23 …”

“…Further, it has been observed that these columns extend into the metaphysis and can be visualized using DTI 17 . However, few studies have addressed this hypothesis in animals 18–20 or humans 17,21–23 …”