H-loop Knotless Double-Row Repair Versus Knotted Suture Bridge for Rotator Cuff Tears: A Biomechanical and Histological Study in an Animal Model [Formula: see text].

BACKGROUND: Knotted suture bridge repair (KSBR) has been widely proven to be an effective method for rotator cuff repairs. However, the occurrence of type 2 failure after suture bridge repair remains a frequent problem because of the stress concentration and disturbance of tendon perfusion in the medial row. The authors have developed the H-loop knotless double-row repair (HLDR) to counteract these problems. PURPOSE: To compare the biomechanical and histological outcomes of HLDR and KSBR for rotator cuff tear in the rabbit model. STUDY DESIGN: Controlled laboratory study. METHODS: Acute bilateral supraspinatus tears were created on the shoulders of 46 New Zealand White rabbits. HLDR and KSBR were randomly performed on the left side or right side. Thirteen animals each were sacrificed at 2, 4, and 8 weeks after surgery (n = 39), with 6 rabbits used for histological evaluation and the other 7 rabbits for biomechanical testing. The remaining 7 animals from the original 46 were only used for initial biomechanical evaluation at week 0. RESULTS: Macroscopically, all repaired tendons were connected to their footprint on the greater tuberosity without postoperative complications at 8 weeks after surgery. The HLDR group had significantly better histological bone-to-tendon integration compared with the KSBR group in terms of fibrocartilage regeneration, collagen composition, and fiber organization. The biomechanical outcomes in the HLDR group were demonstrated to be better than those of the KSBR group at time 0 and 8 weeks after surgery. CONCLUSION: Both repair techniques were effective for rotator cuff tears in a rabbit rotator cuff tear model; however, HLDR demonstrated more advantages in improving biomechanical properties and histological tendon-to-bone healing compared with KSBR. CLINICAL RELEVANCE: This animal study suggested that HLDR might be an alternative choice for rotator cuff tears in humans to increase tendon-to-bone healing and reduce the rate of failure to heal.

R2* value derived from multi-echo Dixon technique can aid discrimination between benign and malignant focal liver lesions.

BACKGROUND: R2* estimation reflects the paramagnetism of the tumor tissue, which may be used to differentiate between benign and malignant liver lesions when contrast agents are contraindicated. AIM: To investigate whether R2* derived from multi-echo Dixon imaging can aid differentiating benign from malignant focal liver lesions (FLLs) and the impact of 2D region of interest (2D-ROI) and volume of interest (VOI) on the outcomes. METHODS: We retrospectively enrolled 73 patients with 108 benign or malignant FLLs. All patients underwent conventional abdominal magnetic resonance imaging and multi-echo Dixon imaging. Two radiologists independently measured the mean R2* values of lesions using 2D-ROI and VOI approaches. The Bland-Altman plot was used to determine the interobserver agreement between R2* measurements. Intraclass correlation coefficient (ICC) was used to determine the reliability between the two readers. Mean R2* values were compared between benign and malignant FFLs using the nonparametric Mann-Whitney test. Receiver operating characteristic curve analysis was used to determine the diagnostic performance of R2* in differentiation between benign and malignant FFLs. We compared the diagnostic performance of R2* measured by 2D-ROI and VOI approaches. RESULTS: This study included 30 benign and 78 malignant FLLs. The interobserver reproducibility of R2* measurements was excellent for the 2D-ROI (ICC = 0.994) and VOI (ICC = 0.998) methods. Bland-Altman analysis also demonstrated excellent agreement. Mean R2* was significantly higher for malignant than benign FFLs as measured by 2D-ROI (P < 0.001) and VOI (P < 0.001). The area under the curve (AUC) of R2* measured by 2D-ROI was 0.884 at a cut-off of 25.2/s, with a sensitivity of 84.6% and specificity of 80.0% for differentiating benign from malignant FFLs. R2* measured by VOI yielded an AUC of 0.875 at a cut-off of 26.7/s in distinguishing benign from malignant FFLs, with a sensitivity of 85.9% and specificity of 76.7%. The AUCs of R2* were not significantly different between the 2D-ROI and VOI methods. CONCLUSION: R2* derived from multi-echo Dixon imaging whether by 2D-ROI or VOI can aid in differentiation between benign and malignant FLLs.

Liver fat accumulation measured by high-speed T2-corrected multi-echo magnetic resonance spectroscopy can predict risk of cholelithiasis.

BACKGROUND: Liver fat accumulation is associated with increased cholesterol synthesis and hypersecretion of biliary cholesterol, which may be related to the development of cholelithiasis. AIM: To investigate whether liver fat accumulation measured by high-speed T2-corrected multi-echo magnetic resonance spectroscopy (MRS) is a risk factor for cholelithiasis. METHODS: Forty patients with cholelithiasis and thirty-one healthy controls were retrospectively enrolled. The participants underwent high-speed T2-corrected multi-echo single-voxel MRS of the liver at a 3T MR scanner. The proton density fat fraction (PDFF) and R2 value were calculated. Serum parameters and waist circumference (WC) were recorded. Spearman's correlation analysis was used to analyze the relationship between PDFF, R2, and WC values. Multivariate logistic regression analysis was carried out to determine the significant predictors of the risk of cholelithiasis. Receiver operating characteristic curve (ROC) analysis was used to evaluate the discriminative performance of significant predictors. RESULTS: Patients with cholelithiasis had higher PDFF, R2, and WC values compared with healthy controls (5.8% ± 4.2% vs 3.3% ± 2.4%, P = 0.001; 50.4 ± 24.8/s vs 38.3 ± 8.8/s, P = 0.034; 85.3 ± 9.0 cm vs 81.0 ± 6.9 cm, P = 0.030; respectively). Liver iron concentration extrapolated from R2 values was significantly higher in the cholelithiasis group (2.21 ± 2.17 mg/g dry tissue vs 1.22 ± 0.49 mg/g dry tissue, P = 0.034) than in the healthy group. PDFF was positively correlated with WC (r = 0.502, P < 0.001) and R2 (r = 0.425, P < 0.001). Multivariate logistic regression analysis showed that only PDFF was an independent risk factor for cholelithiasis (odds ratio = 1.79, 95%CI: 1.22-2.62, P = 0.003). ROC analysis showed that the area under the curve of PDFF was 0.723 for discriminating cholelithiasis from healthy controls, with a sensitivity of 55.0% and specificity of 83.9% when the cut-off value of PDFF was 4.4%. CONCLUSION: PDFF derived from high speed T2-corrected multi-echo MRS can predict the risk of cholelithiasis.

Magnetic Resonance Imaging of Bilateral Hands Is More Optimal Than MRI of Unilateral Hands for Rheumatoid Arthritis.

OBJECTIVE: To explore the advantages of magnetic resonance imaging (MRI) of bilateral hands in rheumatoid arthritis (RA). METHODS: Consecutive patients with active RA were recruited for clinical assessments, radiographs, and MRI of bilateral hands. Bilateral hands were scanned simultaneously on 3.0 T whole-body MRI system and were scored on synovitis, osteitis, and bone erosion according to the RA MRI scoring (RAMRIS) system. RESULTS: Among 120 patients included, wrist bones and metacarpophalangeal joint (MCPJ) 2 proximal showed bone erosion in early RA. The second to fifth metacarpal bases and the second to fourth MCPJ distal showed more bone erosion in mid-stage or late-stage RA. When MRI of dominant unilateral hand was analyzed, MRI synovitis and osteitis in 5% of wrists and 3 MRI features in 5-14% of MCPJ were misdiagnosed (McNemar test, all p < 0.05). There were 46% wrist synovitis, 29-52% MCPJ2-5 synovitis, 45% wrist osteitis, and 20%-34% MCPJ2-5 osteitis not detected by joint tenderness and/or swelling. When the clinically more severe hand was selected for MRI of unilateral hand according to physical examination, MRI synovitis in 5% of wrists and 3 MRI features in 7-15% of MCPJ were misdiagnosed (all p < 0.05). Scatter plots and linear regression analyses were used to illustrate RAMRIS between dominant or selected hand (Y values) and nondominant or nonselected hand (X values). All linear models were markedly different from a Y = X linear model, indicating the dominant or clinically more severe hand could not represent the contralateral hand to evaluate RAMRIS. CONCLUSION: MRI of bilateral hands is more optimal than MRI of the unilateral hand in RA.

DTI metrics can be used as biomarkers to determine the therapeutic effect of stem cells in acute peripheral nerve injury.

PURPOSE: To determine the role of diffusion tensor imaging (DTI) metrics as biomarkers for the therapeutic effects of mesenchymal stem cells (MSCs) in acute peripheral nerve injury. MATERIALS AND METHODS: Forty-four adult rats received subepineurial microinjection of MSCs (n = 22) or phosphate buffered saline (PBS, n = 22) 1 week after the sciatic nerve trunk crush injury. Sequential fat-suppressed T2-weighted imaging, T2 measurement, DTI and sciatic nerve functional assessment were performed at a 3.0 Tesla MR unit over an 8-week follow-up, with histological assessments performed at regular intervals. The sciatic nerve function index, T2 value, and DTI metrics, including fractional anisotropy (FA), axial diffusivity, radial diffusivity (RD), and mean diffusivity values of the distal stumps of crushed nerves were measured and compared between the two groups. RESULTS: Nerves treated with MSCs showed better functional recovery and exhibited more pronounced nerve regeneration compared with nerves treated with PBS. T2 values in nerves treated with MSCs or PBS showed a similar change pattern (P = 0.174), while FA and RD values in nerves treated with MSCs showed more rapid return (one week earlier) to baseline level than nerves treated with PBS (P = 0.045; 0.035). Nerves treated with MSCs had higher FA and lower RD values than nerves treated with PBS during the period from 2 to 3 weeks after surgery (P ≤ 0.0001, 0.004; P = 0.004, 0.006). CONCLUSION: FA and RD values derived from DTI might be used as sensitive biomarkers for detecting the therapeutic effect of stem cells in acute peripheral nerve crush injuries. LEVEL OF EVIDENCE: 2 J. Magn. Reson. Imaging 2017;45:855-862.

rna interference targeting p110ß reduces tumor necrosis factor-alpha production in cellular response to wear particles in vitro and osteolysis in vivo.

Aseptic joint loosening is a key factor that reduces the life span of arthroplasty. There are currently few effective treatments for joint loosening except surgical revision. We explored the inhibitory effects of p110ß-targeted small interfering RNA (siRNA) and lentivirus on particle-induced inflammatory cytokine expression in the murine macrophage cell line, RAW264.7. siRNA- and lentivirus-targeting p110ß were transfected and infected prior to particle stimulation, respectively. Ceramic and titanium particles of different sizes were prepared to stimulate macrophages. Fluorescence microscopy showed that the efficiency of siRNA transfection and lentivirus infection were 74.2 ± 4.2 and 92.3 ± 2.6 %, respectively. TNF-alpha mRNA in the particle stimulation plus RNA interference (RNAi) groups were significantly lower compared with the particle stimulation-only groups (P < 0.05). Similarly, protein levels of TNF-alpha in RNAi-treated groups were significantly decreased after transfection or infection (P < 0.05). It showed that Phosphor-AKT (Ser473) activation was significantly reduced by RNAi through western blot. As assessed by CT, micro-CT and histological analysis, particle implantation induced a significant osteolysis in mice calvaria, which was limited by p110ß lentivirus addition. These results suggested that p110ß subtype of PI3K, followed by activation of Ser473, may possibly participate in the regulation of macrophages activity by wear particles, ultimately resulting in the TNF-α secretion and osteolysis.

Inhibition of the PI3K/AKT pathway reduces tumor necrosis factor-alpha production in the cellular response to wear particles in vitro.

Joint replacement is the most effective treatment for end-stage osteoarticular disease. However, macrophage-mediated aseptic loosening of joint prosthesis severely hampers the clinical effects of joint replacement. Until now, the mechanism by which macrophages regulate the secretion of inflammatory cytokines after particle stimulation is not clear. It is well known that the PI3K/AKT pathway participates in multiple cellular processes, including cell growth, survival, and inflammation. However, whether the PI3K/AKT pathway participates in the proinflammatory response of macrophages after particle stimulation and secondary aseptic loosening is still unknown. In this study, ceramic and titanium particles of different sizes were prepared to stimulate macrophages. LY294002, a specific inhibitor of PI3K, was pretreated prior to particle stimulation. The expression of tumor necrosis factor-alpha (TNF-α) and all the subunits of PI3K and AKT were detected by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot. The result showed that LY294002 could suppress the RNA and protein expression of TNF-α in RAW264.7 cells after stimulation of different particles. The subunits of PI3K (p110ß and p85ß), followed by activation of phosphor-AKT (Ser473), participated in the regulation of activating macrophages by wear particles, ultimately resulting in the secretion of TNF-α.

[Application of multislice spiral CT and 3D reconstruction in diagnosis and treatment of vascular malformations in head and neck].

OBJECTIVE: To explore the application of MS-CT and 3D reconstruction in diagnosis and treatment of vascular malformations in head and neck. METHODS: 20 cases with vascular malformations in head and neck underwent MS-CT and 3-D reconstruction. Then the treatment was determined based on the results of MSCT scanning. The postoperative results were evaluated. RESULTS: The images of MS-CT showed the edge of vascular malformations partially or completely in 16 cases of venous malformations. The lesion's anatomic site and 3-D position was obtained. The 3-D images also showed the overexpanded supply arteries in 4 case of arteriovenous malformations. 2 case of venous malformations in lip underwent resection and healed completely. 12 cases of venous malformations in buccal and floor of mouth were treated with compartmentalized sclerotherapy with partial lesion involution. 2 case of venous malformations in mouth floor were treated with operation followed by sclerotherpy with partial lesion involution. 4 cases of arteriovenous malformations were treated with Superselective Artery Embolization with partial lesion involution. CONCLUSION: MS-CT and 3D reconstruction can play an important role in diagnosis and treatment of vascular malformations in head and neck.

[Diagnostic value of multi-slice spiral CT three dimensional reconstruction in maxillofacial diseases].

OBJECTIVE: To evaluate the diagnostic value of multi-slice spiral CT (MSCT) three dimensional (3D) reconstruction for maxillofacial diseases. METHODS: Sixty patients with maxillofacial diseases underwent the scanning of MSCT with 3D reconstruction. Among them, 34 patients with maxillofacial fracture, 10 patients with maxillofacial tumors and tumor-like diseases, and 16 patients with congenital deformities. The MSCT scanned with slice thickness of 2 mm. The methods of 3D reconstruction included multi-planar reconstruction (MPR), shaded surface display (SSD), and volume rendering (VR). The results were compared with what was observed during operations. RESULTS: Totally 36 cases of maxillofacial fracture were shown by 2D or 3D imaging and were validated by the observations during operation. The MSCT with 3D reconstruction imaging was significantly superior to 2D axial imaging in maxillofacial fracture. Three dimensional imaging could clearly show the spacial anatomy of facial, fragment displacement, and tracing fracture lines. However, 2D imaging had better effectiveness than 3D imaging in observing deep structure and fine fracture. In maxillofacial tumors and tumor-like diseases, 3D imaging was significantly superior to 2D axial imaging in showing the tumor shape and spacial relationships between tumors and surrounding structures. Two dimensional imaging and MPR imaging were excellent to reveal internal structure and pathological changes of tumors. 2D imaging and MPR imaging also achieved better results in showing tumors extended to soft tissues. In maxillofacial congenital deformities, 3D imaging were superior than 2D imaging. CONCLUSION: 3D imaging has an important value in the diagnosis and clinical assessment of maxillofacial fracture, tumor-like diseases, and congenital deformities.