RESUMO
Objective:To explore the value of a radiomics nomogram based on T 1WI for prediction of the relapse of osteosarcoma after surgery within 1 year from multicenter data. Methods:The imaging and clinical data of 107 patients with pathologica1ly confirmed osteosarcoma who received neoadjuvant chemotherapy before surgery from 6 hospitals from January 2009 to October 2017 were retrospectively analyzed. A training cohort consisted of 75 patients from firstly enrolled 4 hospitals and an independent validation cohort of 32 patients from other 2 hospitals. Pretreatment T 1WI was used to extract radiomics features. Least absolute shrinkage and selection operator (LASSO) regression was applied to reduce the dimension and then the radiomics signature was constructed to predict the relapse of osteosarcoma after surgery within 1 year in training cohort. Independent clinical risk factors were screened using one-way logistic regression, and then a radiomics nomogram incorporated the radiomics signature and MRI characteristics was developed by multivariate logistic regression. The predictive nomogram was evaluated using receiver operating characteristic (ROC) curve in the training cohort, and validated in the independent validation cohort. The calibration curve was used to evaluate the agreement between prediction and actual observation and the decision curve was used to demonstrate the clinical usefulness. Results:Based on T 1WI from multicenter institutions, the radiomics signature was built using 2 valuable selected features that were significantly associated with relapse within 1 year. Two selected features included 1 gray-level co-occurrence matrices (GLCM) feature (L_G_1.0_GLCM_homogeneity1, LASSO coefficient 3.122) and 1 gray-level run length matrix (GLRLM) feature (GLRLM_RP, LASSO coefficient -2.474). The prediction nomogram including radiomics signature and MRI characteristics (joint invasion and perivascular involvement) showed good discrimination with the area under the ROC curve of 0.884 and 0.821 in the training and validation cohorts, respectively. The calibration curve showed that the nomogram achieved good agreement between prediction and actual observation. Decision curve analysis demonstrated that the radiomics nomogram was clinically useful when the threshold probability was greater than 21%. Conclusion:The radiomics nomogram based on T 1WI can be used as a non-invasive quantitative tool to predict relapse of osteosarcoma within 1 year before treatment, which provides support for clinical decision-making in osteosarcoma.
RESUMO
Objective To evaluate the reproducibility of normal liver ADC measurements by different respiratory motion compensation techniques. Methods A total of 31 young healthy volunteers who are 20 to 40 years old without any hepatic diseases were selected to research. Each volunteer underwent liver DWI twice in 24 hours with the same parameters and location. The imaging was performed with free-breath(FB), breathhold(BH), rspiratory-triggered(RT)and navigator-triggered(NT)techniques, and the ADC values of the left hepatic lobe and right hepatic lobe (upper, middle and lower) was acquired with two scans. Analysis the the ADC values of various anatomic locations of liver with two-way analysis of variance of randomized block design. Reproducibility of ADCs was assessed with the Bland-Altman method. Analysis of variance and paired-sample t test was used to assess ADCs from both right and left liver lobe among the four techniques. Result The ADC values acquired from the four techniques were significant differences (P<0.01),and the ADC values of the right lobe were less than the left lobe's(P<0.01). It showed a trend to decrease moving from superior to inferior levels in both left and right lobes, and the ADC values among The middle and lower were significant differences (P<0.01). The limit of agreement of ADC of twice imaging among the four techniques were as follow: the right lobe was less than the left lobes, and the breathhold was less the others. As the result, reproducibility in the right liver lobe was better to that in the left and the reproducibility with breathhold was better than the other respiratory motion compensation techniques. Conclusions Both anatomic location and DWI technique influence the liver ADC measurements and their reproducibility. The reproducibility of BH is the best.