The effect of contrast media on the synovial membrane

Groove model of tibia-femoral osteoarthritis in the rat

Several experimental models of osteoarthritis in rats are used to study the pathophysiology of osteoarthritis. Many mechanically induced models have the limitation that permanent joint instability is induced by, for example, ligament transection or meniscal damage. This permanent instability will counteract the potential beneficial effects of therapy. The groove model of osteoarthritis uses a one-time trigger, surgically induced cartilage damage on the femoral condyles, and has been validated for the canine tibia-femoral compartment. The present study evaluates this model for the rat knee joint. The articular cartilage of the weight bearing surface of both femoral condyles and trochlea were damaged (grooved) without damaging the underlying subchondral bone. Severity of joint degeneration was histologically assessed, in addition to patella cartilage damage, and subchondral bone characteristics by means of (contrast-enhanced) micro-CT. Mild histological degeneration of the surgically untouched tibial plateau cartilage was observed in addition to damage of the femoral condyles, without clear synovial tissue inflammation. Contrast enhanced micro-CT demonstrated proteoglycan loss of the surgically untouched patella cartilage. Besides, a more sclerotic structure of the subchondral bone was observed. The tibia-femoral groove model in a rat results in mild knee joint degeneration, without permanent joint instability and joint inflammation. This makes the rat groove model a useful model to study the onset and progression of post-traumatic non-inflammatory osteoarthritis, creating a relatively sensitive model to study disease modifying osteoarthritic drugs. © 2016 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 35:496-505, 2017.

MR arthrography of the shoulder: tolerance evaluation of four different injection techniques

OBJECTIVE

We sought to prospectively evaluate patients' pain perception and technical success of four different arthrographic techniques for shoulder MR arthrography.

MATERIALS AND METHODS

A total of 125 consecutive patients were referred for shoulder MR arthrography. The patients were randomly injected under fluoroscopic guidance (n(1) = 37), with CT guidance using an anterior (n(2) = 29) or a posterior approach (n(3) = 32) and with ultrasound guidance (n(4) = 27). For each patient, absolute periprocedural pain on a numerical rating pain scale (0 = "no pain", 10 = "intolerable pain"), technical success of the method used, and reason for referral were recorded.

RESULTS

The technical success rate was 100% for all injection methods. The results regarding absolute periprocedural pain were as follows: fluoroscopic guidance showed a mean pain of 4.05 ± 1.24, CT anterior guidance demonstrated a mean pain of 3.87 ± 0.95, CT posterior guidance showed a mean pain of 1.59 ± 0.81, and ultrasound guidance a mean pain of 3.63 ± 1.12. A significant difference (p < .05) was observed for the posterior route under CT guidance. The mean pain level was significantly higher for older (> 51 year) female patients.

CONCLUSIONS

No differences were found for the technical success rate of the aforementioned techniques. A CT-guided posterior approach seems to be a more comfortable method for the patient.

Contrast-enhanced CT with a high-affinity cationic contrast agent for imaging ex vivo bovine, intact ex vivo rabbit, and in vivo rabbit cartilage

PURPOSE

To quantify the affinity of a cationic computed tomography (CT) contrast agent (CA(4+)) and that of an anionic contrast agent (ioxaglate) to glycosaminoglycans (GAGs) in ex vivo cartilage tissue explants and to characterize the in vivo diffusion kinetics of CA(4+) and ioxaglate in a rabbit model.

MATERIALS AND METHODS

All in vivo procedures were approved by the institutional animal care and use committee. The affinities of ioxaglate and CA(4+) to GAGs in cartilage (six bovine osteochondral plugs) were quantified by means of a modified binding assay using micro-CT after plug equilibration in serial dilutions of each agent. The contrast agents were administered intraarticularly to the knee joints of five New Zealand white rabbits to determine the in vivo diffusion kinetics and cartilage tissue imaging capabilities. Kinetics of diffusion into the femoral groove cartilage and relative contrast agent uptake into bovine plugs were characterized by means of nonlinear mixed-effects models. Diffusion time constants (τ) were compared by using a Student t test.

RESULTS

The uptake of CA(4+) in cartilage was consistently over 100% of the reservoir concentration, whereas it was only 59% for ioxaglate. In vivo, the contrast material-enhanced cartilage reached a steady CT attenuation for both CA(4+) and ioxaglate, with τ values of 13.8 and 6.5 minutes, respectively (P = .04). The cartilage was easily distinguishable from the surrounding tissues for CA(4+) (12 mg of iodine per milliliter); comparatively, the anionic contrast agent provided less favorable imaging results, even when a higher concentration was used (80 mg of iodine per milliliter).

CONCLUSION

The affinity of the cationic contrast agent CA(4+) to GAGs enables high-quality imaging and segmentation of ex vivo bovine and rabbit cartilage, as well as in vivo rabbit cartilage.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112246/-/DC1.

Effect of SonoVue on the synovial membrane in rabbit knees

OBJECTIVES

The purpose of this study was to evaluate the effect of intra-articular injection of SonoVue (sulfur hexafluoride with a phospholipid shell; Bracco SpA, Milan, Italy) on the synovial membrane in an animal model.

METHODS

Twenty-one New Zealand White rabbits (42 knees) were used in this study. We injected the knees with normal saline (saline group; n = 21) and SonoVue (SonoVue group; n = 21). A histologic examination of the knees was performed out at 3 and 12 hours and 3, 7, 15, 30, and 45 days after injection. Four histologic parameters (synovial hyperplasia, synovial stroma, vascular dilatation, and inflammatory infiltrates) were graded separately.

RESULTS

We found no significant differences in this study for synovial hyperplasia, vascular dilatation, or inflammatory infiltrates between the saline and SonoVue groups. A significant difference was only observed for synovial stroma (P < .05), and most of the histologic changes were mild in the saline group and moderate in the SonoVue group. The histologic changes observed in this study are considered transitory and reversible.

CONCLUSIONS

The results suggest that intra-articular injection of SonoVue is a safe procedure.

Hyperosmolarity protects chondrocytes from mechanical injury in human articular cartilage

The aim of this study was to determine whether exposure of human articular cartilage to hyperosmotic saline (0.9%, 600 mOsm) reduces in situ chondrocyte death following a standardised mechanical injury produced by a scalpel cut compared with the same assault and exposure to normal saline (0.9%, 285 mOsm). Human cartilage explants were exposed to normal (control) and hyperosmotic 0.9% saline solutions for five minutes before the mechanical injury to allow in situ chondrocytes to respond to the altered osmotic environment, and incubated for a further 2.5 hours in the same solutions following the mechanical injury.

Using confocal laser scanning microscopy, we identified a sixfold (p = 0.04) decrease in chondrocyte death following mechanical injury in the superficial zone of human articular cartilage exposed to hyperosmotic saline compared with normal saline.

These data suggest that increasing the osmolarity of joint irrigation solutions used during open and arthroscopic articular surgery may reduce chondrocyte death from surgical injury and could promote integrative cartilage repair.

In vivo imaging of cartilage degeneration using microCT-arthrography

OBJECTIVE

In vivo imaging of cartilage degeneration in small animal models is nowadays practically impossible. In the present study, we investigated the use of micro-computed tomography (microCT) in combination with a negatively charged ionic iodine dimer (ioxaglate) for in vivo assessment of cartilage degeneration in a small animal model.

METHODS

Cartilage degeneration was induced in the right knee of rats by injection of mono-iodoacetate (MIA). We imaged the rat knees with ioxaglate enhanced microCT-arthrography at 4, 16 and 44 days after MIA injection. Subsequently, microCT-arthrographic findings were evaluated and compared with quantitative histology of the patellar cartilage.

RESULTS

In vivo microCT-arthrography clearly detected cartilage degeneration in the rat knee-joints, in which the ioxaglate diffused into the degenerated cartilage layer. Higher microCT-attenuation values and smaller total volumes of the cartilage layer were detected at longer time periods after MIA injection, which is quantitatively confirmed by histology.

CONCLUSION

In vivo microCT-arthrography is a valuable tool for detection of minor cartilage alterations and distinguishes different stages of cartilage degeneration in a small animal model. Since microCT, at the same time, also visualizes osteophyte formation and changes in the underlying subchondral bone structures, the technique will be very useful for longitudinal overall assessment of the development of (osteo)arthritis and to study interventions in small animal models.