Signal-inducing bone cements for MRI-guided spinal cementoplasty: evaluation of contrast-agent-based polymethylmethacrylate cements

Objective

The purpose of this work is to evaluate two signal-inducing bone cements for MRI-guided spinal cementoplasty.

Materials and methods

The bone cements were made of polymethylmethacrylate (PMMA, 5?ml monomeric, 12?g polymeric) and gadoterate meglumine as a contrast agent (CA, 0–40?μl) with either saline solution (NaCl, 2–4?ml) or hydroxyapatite bone substitute (HA, 2–4?ml). The cement’s signal was assessed in an open 1-Tesla MR scanner, with T1W TSE and fast interventional T1W TSE pulse sequences, and the ideal amount of each component was determined. The compressive and bending strength for different amounts of NaCl and HA were evaluated.

Results

The cement’s MRI signal depended on the concentration of CA, the amount of NaCl or HA, and the pulse sequence. The signal peaks were recorded between 1 and 10?μl CA per ml NaCl or HA, and were higher in fast T1W TSE than in T1W TSE images. The NaCl-PMMA-CA cements had a greater MRI signal intensity and compressive strength; the HA-PMMA-CA cements had a superior bending strength.

Conclusions

Concerning the MR signal and biomechanical properties, these cements would permit MRI-guided cementoplasty. Due to its higher signal and greater compressive strength, the NaCl-PMMA-CA compound appears to be superior to the HA-PMMA-CA compound.     

Comparison of cytokine levels from undiluted vitreous of untreated patients with retinal vein occlusion

Purpose: To compare cytokines in undiluted vitreous of treatment‐naïve patients with macular oedema without vitreomacular traction secondary to branch (BRVO), central (CRVO) and hemi‐central (H‐CRVO) retinal vein occlusion. Methods: Ninety‐four patients (median age 72 years, 42 men) underwent an intravitreal combination therapy, including a single‐site 23‐gauge core vitrectomy and the application of bevacizumab and dexamethasone due to vision‐decreasing macular oedema. Among these were 43 patients with BRVO, 35 with CRVO and 16 patients with hemi‐CRVO, which were distributed in a fresh or old retinal vein occlusion type (seven or more months after onset). Undiluted vitreous samples were analysed for interleukin 6 (IL‐6), monocyte chemoattractant protein‐1 (MCP‐1) and vascular endothelial growth factor (VEGF‐A) with cytometric BEAD assay. Vitreous samples from patients with idiopathic epiretinal membrane served as controls (n = 14). Results: The mean cytokine values were highest in the CRVO group with IL‐6 = 64.7 pg/ml (SD ± 115.8), MCP‐1 = 1015.8 pg/ml (±970.1) and VEGF‐A = 278.4 pg/ml (±512.8), followed by the H‐CRVO group with IL‐6 = 59.9 pg/ml (SD ± 97.5), MCP‐1 = 938.8 pg/ml (±561.1) and VEGF‐A = 211.5 pg/ml (±232.4). The BRVO group had IL‐6 = 23.2 pg/ml (SD ± 48.8), MCP‐1 = 602.6 pg/ml (±490.3) and VEGF‐A = 161.8 pg/ml (±314.4). The values of MCP‐1 and VEGF‐A were significantly different for CRVO or H‐CRVO versus BRVO. All values were significantly higher than in the control samples, which had 6.2 ± 3.4 pg/ml (IL‐6), 253 ± 74 pg/ml (MCP‐1) and 7 ± 4.9 pg/ml (VEGF‐A). Within the old RVO type, only MCP‐1 was significantly different for CRVO or H‐CRVO versus BRVO. Conclusions: Both inflammatory markers and VEGF‐A were higher in CRVO and H‐CRVO than in BRVO undiluted vitreous samples. It seems that monocyte recruitment to the vessel wall, which might underlie the importance of eosinophils in tissue remodelling after RVO, is of special interest owing to the significant difference in MCP‐1 in the older RVO types.     

Electroretinographic findings associated with panretinal photocoagulation (PRP) versus PRP plus intravitreal ranibizumab treatment for high-risk proliferative diabetic retinopathy

To evaluate changes in electroretinographic (ERG) findings after panretinal photocoagulation (PRP) compared to PRP plus intravitreal injection of ranibizumab (IVR) in eyes with high-risk proliferative diabetic retinopathy (PDR). Patients with high-risk PDR and no prior laser treatment were assigned randomly to receive PRP (PRP group; n = 9) or PRP plus IVR (PRPplus group; n = 11). PRP was administered in two sessions (weeks 0 and 2), and IVR was administered at the end of the first laser session (week 0) in the PRPplus group. Standardized ophthalmic evaluations including (ETDRS) best-corrected visual acuity (BCVA), and fluorescein angiography to measure area of fluorescein leakage (FLA), were performed at baseline and at weeks 16 (±2), 32 (±2) and 48 (±2). ERG was measured according to ISCEV standards at baseline and at week 48 (±2). At 48 weeks, 2,400–3,000 laser spots had been placed in eyes in the PRP group, while only 1,400–1,800 spots had been placed in the PRPplus group. Compared to baseline, there was a statistically significant (P < 0.05) FLA reduction observed at all study visits in both groups, with the reduction observed in the PRPplus group significantly larger than that in the PRP group at week 48. ROD b-wave amplitude was significantly reduced to 46 ± 5 % (P < 0.05) of baseline in the PRP group and 64 ± 6 % (P < 0.05) in the PRPplus group. This reduction was significantly larger in the PRP group than in the PRPplus group (P = 0.024; t Test). Similar results were observed for the dark-adapted Combined Response (CR) b-wave amplitude, with a reduction at 48 weeks compared to baseline of 45 ± 4 % in the PRP group and 62 ± 5 % in the PRPplus group; the reduction in CR b-wave amplitude was significantly larger in the PRP group than in the PRPplus group (P = 0.0094). CR a-wave, oscillatory potentials, cone single flash, and 30 Hz flicker responses showed statistically significant within-group reductions, but no differences in between-group analyses. These results suggest that treating high-risk PDR with PRP plus IVR is effective for PDR control, and permits the use of less extensive PRP which, in turn, induces less retinal functional loss, in particular for rod-driven post-receptoral responses, than treatment with PRP alone.