Magnetic resonance image compilation sequence to quantitatively detect active sacroiliitis with axial spondyloarthritis.

Background: To evaluate the diagnostic value of quantitative parameters [T1, T2, and proton density (PD) value] generated from magnetic resonance image compilation (MAGiC) sequence for active sacroiliitis in the patients with axial spondyloarthritis (ax-SpA). Methods: A total of 90 consecutive ax-SpA patients were recruited and divided into an active group (n=48) and inactive group (n=42) based on the Spondyloarthritis Research Consortium Canada (SPARCC) score in this prospective study. In addition, 47 healthy volunteers were recruited as the control group. All participants underwent magnetic resonance (MR) scanning (including MAGiC sequence and T2 mapping sequence) to obtain the T1 value, T2 value, PD value of MAGiC sequence (MAGiC T1 value, T2 value, PD value), and the T2 value of T2 mapping sequence (T2 map T2 value). Intraclass correlation coefficients (ICC) were calculated to assess the inter­ and intra­observer agreement. The correlation between the MAGiC T2 value and the T2 map T2 value was analyzed using Spearman's Rho. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) analysis were performed for all parameters. Results: For the active group, inactive group, and control group, the MAGiC T1 value, T2 value, PD value, and T2 map T2 value were (1,700.91±725.40, 546.58±59.49, 640.25±95.79 ms), (129.37±23.85, 117.16±20.37, 90.52±12.05 ms), (76.47±15.92, 82.69±9.51, 75.51±9.17 pu), and (96.75±16.06, 87.96±9.27, 82.03±10.17 ms), respectively. The difference of the MAGiC T1 value and the MAGiC T2 value in the three groups was statistically significant (P<0.05). The MAGiC PD value was only statistically significant between inactive and control groups (P=0.001). When comparing the ROC curves of quantitative values among the three groups, MAGiC T1 value showed higher diagnostic efficacy than MAGiC T2 value between the active and inactive groups (MAGiC T1AUC: 0.971, MAGiC T2AUC: 0.655, P<0.0001), and the MAGiC T2 value showed higher diagnostic efficacy than T2 map T2 value between the active group and control group, and the inactive group and control group (MAGiC T2AUC: 0.940, T2 map T2AUC: 0.784, P=0.0021; MAGiC T2AUC: 0.877, T2 map T2AUC: 0.644, P=0.0011). The consistency of measurements was excellent (ICC =0.972-0.998). The MAGiC T2 value was positively correlated with the T2 map T2 value, but with a low correlation (r=0.402; P<0.001). Conclusions: A significant difference was detected between the MAGiC T1 and T2 values among the three groups, while MAGiC PD value had limited diagnostic value. MAGiC T1 value was better at differentiating the active group and inactive group than MAGiC T2 value. MAGiC T2 value was better at differentiating the active group and control group, the inactive group and control group than T2 map T2 value.

Radiomics Nomograms Based on Non-enhanced MRI and Clinical Risk Factors for the Differentiation of Chondrosarcoma from Enchondroma.

BACKGROUND: Differentiating chondrosarcoma from enchondroma using conventional MRI remains challenging. An effective method for accurate preoperative diagnosis could affect the management and prognosis of patients. PURPOSE: To validate and evaluate radiomics nomograms based on non-enhanced MRI and clinical risk factors for the differentiation of chondrosarcoma from enchondroma. STUDY TYPE: Retrospective. POPULATION: A total of 103 patients with pathologically confirmed chondrosarcoma (n = 53) and enchondroma (n = 50) were randomly divided into training (n = 68) and validation (n = 35) groups. FIELD STRENGTH/SEQUENCE: Axial non-contrast-enhanced T1-weighted images (T1WI) and fat-suppressed T2-weighted images (T2WI-FS) were acquired at 3.0 T. ASSESSMENT: Clinical risk factors (sex, age, and tumor location) and diagnosis assessment based on morphologic MRI by three radiologists were recorded. Three radiomics signatures were established based on the T1WI, T2WI-FS, and T1WI + T2WI-FS sequences. Three clinical radiomics nomograms were developed based on the clinical risk factors and three radiomics signatures. STATISTICAL TESTS: The area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of radiomics signatures and clinical radiomics nomograms. RESULTS: Tumor location was an important clinical risk factor (P < 0.05). The radiomics signature based on T1WI and T1WI + T2WI-FS features performed better than that based on T2WI-FS in the validation group (AUC in the validation group: 0.961, 0.938, and 0.833, respectively; P < 0.05). In the validation group, the three clinical radiomics nomograms (T1WI, T2WI-FS, and T1WI + T2WI-FS) achieved AUCs of 0.938, 0.935, and 0.954, respectively. In all patients, the clinical radiomics nomogram based on T2WI-FS (AUC = 0.967) performed better than that based on T2WI-FS (AUC = 0.901, P < 0.05). DATA CONCLUSION: The proposed clinical radiomics nomogram showed promising performance in differentiating chondrosarcoma from enchondroma. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY: Stage 2.

Diagnostic accuracy of dual-energy CT virtual non-calcium images with different related contrast material values for the detection of bone marrow edema in knee.

PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of different related contrast material (Rel.CM) values in dual-energy computed tomography (DECT) virtual non-calcium (VNCa) images for the detection of bone marrow edema (BME) in knee. METHOD: This prospective study was approved by the institutional research ethics board, and written informed consent was obtained from all participants. Twenty-three patients (24 knees) who underwent dual-energy CT and MRI within three weeks from July 2018 to June 2019 with a definite history of trauma were enrolled. Each knee was divided into 12 regions. First, MR images served as the reference standard, Receiver operating characteristic (ROC) curve was used and diagnostic accuracy of VNCa images corresponding to different Rel.CM values (1.25, 1.35, 1.45, 1.55, 1.65, 1.75) were analyzed, aimed to select an optimal Rel.CM value of VNCa images for detecting BME. Then, CT values of the normal areas and BME areas were measured on the VNCa images corresponding to the optimal Rel.CM value for preliminary quantitative analysis. The rank-sum test was used to compare the differences of CT values between BME areas and normal bone marrow areas on the VNCa images. RESULTS: The 24 knees were divided into 288 areas. MR Imaging showed BME in 121 areas. The areas under the ROC curve with different Rel.CM values (1.25, 1.35, 1.45, 1.55, 1.65, and 1.75) were 0.633, 0.674, 0.882, 0.684, 0.651, and 0.649, respectively. On the VNCa images of Rel.CM = 1.45, the diagnostic accuracy was the highest (up to 89.2 %), the CT values of the BME area and the normal area were -67.9 (1.7∼-100.1) HU and -94.5 (-69.7∼-144.9) HU, respectively, with statistical significance (Z=-9.804, P < 0.05). CONCLUSIONS: The VNCa images with a Rel.CM value of 1.45 is optimal for the detection of BME in knee.

[Radiomics models based on non-enhanced MRI can differentiate chondrosarcoma from enchondroma].

OBJECTIVE: To develop and validate radiomics models based on non-enhanced magnetic resonance (MR) imaging for differentiating chondrosarcoma from enchondroma. METHODS: We retrospectively evaluated a total of 68 patients (including 27 with chondrosarcoma and 41 with enchondroma), who were randomly divided into training group (n=46) and validation group (n=22). Radiomics features were extracted from T1WI and T2WI-FS sequences of the whole tumor by two radiologists independently and selected by Low Variance, Univariate feature selection, and least absolute shrinkage and selection operator (LASSO). Radiomics models were constructed by multivariate logistic regression analysis based on the features from T1WI and T2WI-FS sequences. The receiver-operating characteristics (ROC) curve and intraclass correlation coefficient (ICC) analyses of the radiomics models and conventional MR imaging were performed to determine their diagnostic accuracy. RESULTS: The ICC value for interreader agreement of the radiomics features ranged from 0.779 to 0.923, which indicated good agreement. Ten and 11 features were selected from the T1WI and T2WI-FS sequences to construct radiomics models, respectively. The areas under the curve (AUCs) of T1WI and T2WI-FS models were 0.990 and 0.925 in training group and 0.915 and 0.855 in the validation group, respectively, showing no significant differences between the two sequence-based models (P>0.05). In all the cases, the AUCs of the two radiomics models based on T1WI and T2WI-FS sequences and conventional MR imaging were 0.955, 0.901 and 0.569, respectively, demonstrating a significantly higher diagnostic accuracy of the two sequence-based radiomics models than conventional MR imaging (P<0.01). CONCLUSIONS: The radiomics models based on T1WI and T2WI-FS non-enhanced MR imaging can be used for the differentiation of chondrosarcoma from enchondroma.

Potent in vitro synergism of fusidic acid (FA) and berberine chloride (BBR) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).

It was found in the present study that combined use of fusidic acid (FA) and berberine chloride (BBR) offered an in vitro synergistic action against 7 of the 30 clinical methicillin-resistant Staphylococcus aureus (MRSA) strains, with a fractional inhibitory concentration (FIC) index ranging from 0.5 to 0.19. This synergistic effect was most pronounced on MRSA 4806, an FA-resistant isolate, with a minimum inhibitory concentration (MIC) value of 1,024 µg/ml. The time-kill curve experiment showed that FA plus BBR yielded a 4.2 log10 c.f.u./ml reduction in the number of MRSA 4806 bacteria after 24-h incubation as compared with BBR alone. Viable count analysis showed that FA plus BBR produced a 3.0 log10 c.f.u./ml decrease in biofilm formation and a 1.5 log10 c.f.u./ml decrease in mature biofilm in viable cell density as compared with BBR alone. In addition, phase contrast micrographs confirmed that biofilm formation was significantly inhibited and mature biofilm was obviously destructed when FA was used in combination with BBR. These results provide evidence that combined use of FA and BBR may prove to be a promising clinical therapeutic strategy against MRSA.

Lyapunov exponents, dual Lyapunov exponents, and multifractal analysis.

It is shown that the multifractal property is shared by both Lyapunov exponents and dual Lyapunov exponents related to scaling functions of one-dimensional expanding folding maps. This reveals in a quantitative way the complexity of the dynamics determined by such maps. (c) 1999 American Institute of Physics.