Cartilage Blood Flow Correlates With Timing of Ossification in Neonates

The objective of a recent prospective study was to examine gray-scale and Doppler ultrasound patterns of blood supply of early, late, and nonossifying cartilage.

The study has shown that cartilage blood flow correlates with timing of ossification, and observation of flow may prognosticate normality of growth.

Participants
42 child volunteers were recruited from well-baby clinics and a neonatal nursery.

Methodology
3 groups of cartilage based on ossifying characteristics were studied. Group A represented early ossifying cartilaginous centers archetypically chosen to be the chondroepiphysis of the left femoral head.

Group A subgroup included other early ossifying epiphyseal centers such as proximal humeral and proximal tibial epiphyses.

Group B cartilage centers were determined to be later ossifying centers, and the patella was the archetype of this kind of cartilage.

Group C was defined as nonossifying cartilage as noted in the body of the rib cartilage.

The different groups were studied with the same equipment by the same radiologist. Doppler gain was adjusted to identify the destination of the largest vessels. For anatomic comparisons, 2 cryomicrotome sections of a full-term cadaver, and angiographic studies done by a prior investigator were used.

Results
Subjects ranged in age from 0.1 to 11.0 weeks. Early ossifying cartilage studied in group A revealed consistent findings. These included color Doppler ultrasound showing arteries radiating toward the epiphyseal center, correlating with gray-scale imaging findings and cryomicrotome sections.

The artery approaching the ossific nucleus had the greatest color intensity corresponding to the greatest velocity. The peak systolic velocity of a representative vessel was found to strongly correlate with age of subjects in weeks.

In group A subgroup, which examined other early ossifying cartilage centers, feeding vessels had either a radiating pattern toward the center or were concentrated mostly near the preossification or ossification center. Again, peak systolic velocities correlated strongly with age in weeks.

For group B, Doppler ultrasound revealed less vascularity with a narrow systolic base with a more amorphous and hypoechoic appearance on gray-scale. Echogenic striations appeared much later, correlating to age 14 to 24 months.

Group C cartilage revealed no echogenic stripes on gray-scale and no discernable flow on Doppler images.

Conclusions
Gray-scale ultrasound appearances of the 3 groups of cartilage were vastly different. Only when the patellar cartilage approached the preossification/ossification phase did it become more echogenic with increased stripes of vascular channels. Nonossifying cartilage did not have echogenic vascular canals and no flow on Doppler images. Findings were concordant with cryomicrotome findings and angiographic experiments from prior investigators.

Reviewer’s Comments
The study is an excellent academic exercise in revealing the accuracy of ultrasound in assessing vascular and structural characteristics of different cartilage. One would imagine the practical applications to be very narrow, with the majority of beneficiaries of this research likely being other researchers.

Author: Basil Hubbi, MD

Reference:
Yousefzadeh DK, Doerger K, Sullivan C. The Blood Supply of Early, Late, and Nonossifying Cartilage: Preliminary Gray-Scale and Doppler Assessment and Their Implications. Pediatr Radiol; 2008; 38 (February): 146-158