Differences in the vascular tree of the femoral trochlear growth cartilage at osteochondrosis‐susceptible sites in foals revealed by SWI 3T MRI

Abstract

Focal ischemic chondronecrosis of epiphyseal growth cartilage (EGC) during endochondral ossification is believed to be a key early event on the pathway to osteochondrosis (OC) in both animals and humans. The lateral ridge of the equine trochlea is a site where severe osteochondritis dissecans lesions frequently arise and is a model for the study of naturally occurring disease. Noninvasive imaging to investigate EGC vascularity may help elucidate why focal ischemia occurs. 3T MRI susceptibility-weighted imaging (SWI) of femoral trochlea of OC predisposed (n ¼ 10) and control (n ¼ 6) day-old foals, with minimal joint loading after birth, was performed. SWI and 3D images revealed the EGC vascular architecture without a contrast agent, and matched histologic observations. No vascular lesions were identified. There was no difference in the vascular density and architecture between control and OC specimens, but a striking difference in vascular pattern was seen at the OC-predilected site in the lateral ridge of the trochlea in all specimens, when compared to the medial ridge of the trochlea, where OC lesions are rarely observed. This site was less ossified with more perichondrial vessels not yet bridging with the subchondral bone. Furthermore, the mean vascular density of all specimens was significantly higher at this site. We speculate that joint morphology and focal internal trauma on this site with a unique vascular architecture may trigger ischemic events at this site. SWI permitted visualization of EGC in young foals with a clinical 3T MRI and paves the way for non-destructive longitudinal studies to improve understanding of OC in all species. ß

Validation of the ultrasonographic assessment of the femoral trochlea epiphyseal cartilage in foals at osteochondrosis predilected sites with magnetic resonance imaging and histology

“…d–f) Site‐matched 3T SWI MRI images. The cartilage is grey, blood vessels are dark and ossification centre is black as described previously . The blood vessels on SWI images have a similar disposition (yellow arrows) as the echoic flecks within the epipyseal cartilage on ultrasonographic images.…”

In vivo visualization using MRI T2 mapping of induced osteochondrosis and osteochondritis dissecans lesions in goats undergoing controlled exercise

“…Further acceleration of the imaging process might be achieved by using multiband RF pulses as shown in diffusion MRI for functional brain studies . In spite of their demonstrated ex vivo utility in the diagnosis of subclinical OC lesions in vivo evaluation of susceptibility weighted imaging, RAFF and T 1ρ sequences were not included in this study because of imaging time restrictions and/or their limited availability on clinical magnets.…”

“…Quantitative MRI techniques, including cartilage maps created using T 2 −, RAFF (relaxation along a fictitious field)−, or T 1ρ − relaxation times, were able to identify surgically induced, subclinical lesions of OC ex vivo at various stages in their temporal development . Susceptibility weighted imaging and quantitative susceptibility mapping have also been used to describe the vascular architecture of the epiphyseal growth cartilage at the distal femoral predilection site of OC in human beings, pigs, horses, and goats ex vivo . The goat model of induced cartilage necrosis has been used in several ex vivo studies, in spite of its known shortcoming that induced subclinical OC lesions to date have failed to progress to OCD in the operated goats.…”

Differences in third metacarpal trabecular microarchitecture between the parasagittal groove and condyle at birth and in adult racehorses

“…One limb was included from each animal. The McIII were from osteochondrosis predisposed (n = 5) and control foals (n = 3) . The specimens were wrapped in a wet gauze and stored in sealed plastic bags at −20°C until processed.…”