Diffusion-Tensor Imaging of the Physes: A Possible Biomarker for Skeletal Growth—Experience with 151 Children

Abstract

Purpose To determine the changes of diffusion-tensor imaging (DTI) and tractography in the distal femur and proximal tibia related to age, sex, and height. Materials and Methods Following institutional review board approval, with waiver of consent and with HIPAA compliance, the authors retrospectively analyzed DTI images of the knee in 151 children, 73 girls (median age, 14.1 years; range, 6.5-17.8 years) and 78 boys (median age, 16.6 years; range, 6.9-17.9 years), studied from January 2013 to October 2014. At sagittal echo-planar DTI (20 directions, b values of 0 and 600 sec/mm), regions of interest were placed in the tibial and femoral physes. Using a fractional anisotropy threshold of 0.15 and an angle threshold of 40°, the authors performed tractography and measured apparent diffusion coefficient (ADC) and tract length and volume. Changes related to age, sex, and height were evaluated by using fitted nonlinear polynomial functions on bootstrapped samples. Results Femoral tract volume and length increased and then decreased with age (P < .001); the peaks of femoral tract volume are consistent with the growth spurt, occurring earlier in girls (10.8 years) than in boys (13.0 years) (P < .001). Girls had smaller tract volumes in comparison to boys (P = .013). ADC peaks 2 years earlier than tract volume (girls at 9.3 years, boys at 11.0 years). Girls with greater than 50th percentile of height had longer tracts and greater tract volumes compared with girls with less than 50th percentile (P < .020). DTI parameters of boys do not correlate with percentile of height (P > .300). Conclusion DTI of the physis and metaphysis shows greater tract length and volumes in subjects who are at ages when the growth is fastest. ADC and tract length and volume have an earlier and smaller peak in girls than in boys. Femoral tract length and volume are larger in taller girls. RSNA, 2017.

Diffusion tractography of the rat knee at microscopic resolution

“…Jaimes et al found that in vivo DTI and tractography showed the columnar microstructure of the physis and adjacent metaphysis, and provides further insight into normal growth . Their extended study demonstrated that DTI and tractography in the distal femur and proximal tibia related to age, sex, and height . Our results agree with these findings that DTI and tractography can detect the arrangement and structural characteristics of the physis and adjacent metaphysis.…”

“…Recently, Achilles tendon diffusion properties of healthy participants and tendinopathy patients were investigated on a clinical MR scanner with the Achilles positioned at the magic angle (~55°) to main magnetic field for the maximum tendon MR signal . DTI of growing ends of long bones demonstrated the columnar structure in the physis and metaphysis of the knee . Tractography of the thin‐layer articular cartilage is still challenging because of the lower FA values compared to tendon and ligaments …”

Evaluating growth failure with diffusion tensor imaging in pediatric survivors of high-risk neuroblastoma treated with high-dose cis-retinoic acid

“…Magnetic resonance imaging (MRI) of the right knee was performed at 3 T (Verio; Siemens Medical Systems, Erlangen, Germany) using a 15-channel knee coil (Quality Electrodynamics, Mayfield Village, OH). DTI parameters were identical to those of previous studies of physeal DTI [16,17]. To assess reliability, we obtained two sagittal DTI sequences per participant.…”

“…Cis-retinoic acid, a biological agent used to treat high-risk neuroblastoma, has a strong impact on physeal function resulting in reduced physeal thickness and disintegrated loss of columnar architecture [13][14][15]. Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are used to evaluate physeal and metaphyseal structure and function [16,17]. Previous studies in healthy subjects show that DTI depicts a region with tracts parallel to the main axis of the bone that coincides roughly with the physis and metaphyseal spongiosa.…”

Characterization complex collagen fiber architecture in knee joint using high‐resolution diffusion imaging

“…The application of DTI to musculoskeletal system has been growing recently, but there are challenges for the knee joint, arising from the complex anatomy of knee joint, low FA values, and short T2/ values. DTI tractography has been used to detect the integrity of individual connective tissues, such as Achilles tendon, growth plate, and anterior cruciate ligament (ACL) graft in clinical scanners . Tractography of the articular cartilage in rat knee joint has also been reported with DTI at microscopic resolution …”