Prediction of Histologic Neoadjuvant Chemotherapy Response in Osteosarcoma Using Pretherapeutic MRI Radiomics.

Histologic response to chemotherapy for osteosarcoma is one of the most important prognostic factors for survival, but assessment occurs after surgery. Although tumor imaging is used for surgical planning and follow-up, it lacks predictive value. Therefore, a radiomics model was developed to predict the response to neoadjuvant chemotherapy based on pretreatment T1-weighted contrast-enhanced MRI. A total of 176 patients (median age, 20 years [range, 5-71 years]; 107 male patients) with osteosarcoma treated with neoadjuvant chemotherapy and surgery between January 2007 and December 2018 in three different centers in France (Centre Léon Bérard in Lyon, Centre Hospitalier Universitaire de Nantes in Nantes, and Hôpital Cochin in Paris) were retrospectively analyzed. Various models were trained from different configurations of the data sets. Two different methods of feature selection were tested with and without ComBat harmonization (ReliefF and t test) to select the most relevant features, and two different classifiers were used to build the models (an artificial neural network and a support vector machine). Sixteen radiomics models were built using the different combinations of feature selection and classifier applied on the various data sets. The most predictive model had an area under the receiver operating characteristic curve of 0.95, a sensitivity of 91%, and a specificity 92% in the training set; respective values in the validation set were 0.97, 91%, and 92%. In conclusion, MRI-based radiomics may be useful to stratify patients receiving neoadjuvant chemotherapy for osteosarcomas. Keywords: MRI, Skeletal-Axial, Oncology, Radiomics, Osteosarcoma, Pediatrics Supplemental material is available for this article. © RSNA, 2022.

Early detection of multiple bone and extra-skeletal metastases by body magnetic resonance imaging (BMRI) after treatment of Myxoid/Round-Cell Liposarcoma (MRCLS).

INTRODUCTION: Myxoid Round cell containing myxoid liposarcomas (MRCLS) have a high propensity to metastasize to soft tissue and bone. Whole Body Magnetic Resonance Imaging (BMRI) has been reported as a critical modality to early detect disease spreading in asymptomatic patients. The purpose of this study is to describe metastatic patterns and outcomes in patients through annual BMRI surveillance after diagnosis of MRCLS of the extremities and trunk. MATERIEL AND PATIENTS: This retrospective study included patients with histology confirmed MRCLS. Initial BMRI were done within 6 months following the first line treatment then once a year. RESULTS: Forty-five out of 51 consecutive MRCLS patients were included. At the last follow-up 10 patients (22.2%) had an extra-pulmonary soft-tissue or/and bone metastasis detected in a median delay of 22.7±16 months [0-49] from the diagnosis of the MRCLS. Nine patients were asymptomatic. Finally, 5-years metastatic free survival was 72±8%. All metastatic patients had multiple lesion within the year following the first lesion diagnosis. CONCLUSION: Systematic BMRI in MRCLS patients following treatment frequently identify extra-pulmonary metastasis in asymptomatic patients within the first 5 years of follow-up. Despite a long survival can be expected after diagnosis, extra-skeletal metastasis was a signal of disseminated disease.

Wait-and-see policy as a first-line management for extra-abdominal desmoid tumors.

BACKGROUND: Extra-abdominal desmoid tumors are rare, locally aggressive neoplasms without metastatic potential. There is no clear consensus regarding their optimal management. The disappointing results of current treatments and the ability of extra-abdominal desmoid tumors to spontaneously stabilize have increasingly drawn interest toward conservative management. The objective of this study was to evaluate a wait-and-see policy as a first-line management for extra-abdominal desmoid tumors. METHODS: This two-center retrospective study involved fifty-five patients with a histologically proven extra-abdominal desmoid tumor. The primary outcome was the cumulative probability of dropping out from the wait-and-see policy. The wait-and-see policy included aggressive management of symptoms. We conducted a review of the relevant published series in which a watchful-waiting strategy was used. RESULTS: The cumulative probability of dropping out from the wait-and-see policy was 9.6% at the time of the last follow-up. Spontaneous arrest of tumor growth was noted for forty-seven patients (85%) over the course of the study. Half of the tumors were stabilized at one year, and a potential to increase beyond three years was a sporadic event (one case). Regrowth was found in two patients (4%). CONCLUSIONS: A wait-and-see policy is an effective front-line management for patients with primary or recurrent extra-abdominal desmoid tumor. These tumors tend to stabilize spontaneously, on average after one year of evolution, and the cumulative probability of the failure of a wait-and-see policy is approximately 10%.