Imaging of soft-tissue sarcomas

Tumor cellularity beyond the visible in soft tissue sarcomas: Results of an ADC-based, single center, and preliminary radiomics study

PURPOSE

Soft tissue sarcomas represent approximately 1% of all malignancies, and diagnostic radiology plays a significant role in the overall management of this rare group of tumors. Recently, quantitative imaging and, in particular, radiomics demonstrated to provide significant novel information, for instance, in terms of prognosis and grading. The aim of this study was to evaluate the prognostic role of radiomic variables extracted from apparent diffusion coefficient (ADC) maps collected at diagnosis in patients with soft tissue sarcomas in terms of overall survival and metastatic spread as well as to assess the relationship between radiomics and the tumor grade.

METHODS

Patients with histologically proven soft tissue sarcomas treated in our tertiary center from 2016 to 2019 who underwent an Magnetic Resonance (MR) scan at diagnosis including diffusion-weighted imaging were included in this retrospective institution review board-approved study. Each primary lesion was segmented using the b50 images; the volumetric region of interest was then applied on the ADC map. A total of 33 radiomic features were extracted, and highly correlating features were selected by factor analysis. In the case of feature/s showing statistically significant results, the diagnostic accuracy was computed. The Spearman correlation coefficient was used to evaluate the relationship between the tumor grade and radiomic features selected by factor analysis. All analyses were performed applying p<0.05 as a significant level.

RESULTS

A total of 36 patients matched the inclusion criteria (15 women; mean age 58.9 ± 15 years old). The most frequent histotype was myxofibrosarcoma (16.6%), and most of the patients were affected by high-grade lesions (77.7%). Seven patients had pulmonary metastases, and, altogether, eight were deceased. Only the feature Imc1 turned out to be a predictor of metastatic spread (p=0.045 after Bonferroni correction) with 76.7% accuracy. The value -0.16 showed 73.3% sensitivity and 71.4% specificity, and patients with metastases showed lower values (mean Imc1 of metastatic patients -0.31). None of the examined variables was a predictor of the overall outcome (p>0.05, each). A moderate statistically significant correlation emerged only between Imc1 and the tumor grade (r=0.457, p=0.005).

CONCLUSIONS

In conclusion, the radiomic feature Imc1 acts as a predictor of metastatic spread in patients with soft tissue sarcomas and correlates with the tumor grade.

Descriptive epidemiology of soft tissue and bone sarcomas in Lebanon

OBJECTIVES

Most epidemiologic studies on soft tissue sarcomas (STS) and bone sarcomas (BS) are performed in western countries, with few in the Middle East and North Africa region. We describe the epidemiology of sarcomas in Lebanon using the medical records database at the American University of Beirut Medical Center (AUBMC).

METHODS

This single-center retrospective cohort study included patients with sarcomas registered in the database between 2015 and 2019. Their charts were reviewed for baseline characteristics, tumor biology and location, treatment modalities, recurrence, metastasis, and death.

RESULTS

The cohort included 234 patients with STS and 99 patients with BS. Most tumors were <10 cm in size. The most common subtypes were liposarcoma for STS and osteosarcoma for BS. The most common location of STS was the thigh. The most frequent sites of STS metastasis were the lungs. Histological subtype, smoking status, and tumor size and grade were significant for progression-free survival (PFS) in patients with STS. By multivariable analysis, smoking was significantly associated with poorer PFS in STS. For BS, only tumor grade was significant for PFS.

CONCLUSION

The epidemiology of sarcomas at AUBMC is similar to that previously reported. Smoking history was associated with poorer survival in patients with STS.

Deep Learning Networks for Automatic Retroperitoneal Sarcoma Segmentation in Computerized Tomography

The volume estimation of retroperitoneal sarcoma (RPS) is often difficult due to its huge dimensions and irregular shape; thus, it often requires manual segmentation, which is time-consuming and operator-dependent. This study aimed to evaluate two fully automated deep learning networks (ENet and ERFNet) for RPS segmentation. This retrospective study included 20 patients with RPS who received an abdominal computed tomography (CT) examination. Forty-nine CT examinations, with a total of 72 lesions, were included. Manual segmentation was performed by two radiologists in consensus, and automatic segmentation was performed using ENet and ERFNet. Significant differences between manual and automatic segmentation were tested using the analysis of variance (ANOVA). A set of performance indicators for the shape comparison (namely sensitivity), positive predictive value (PPV), dice similarity coefficient (DSC), volume overlap error (VOE), and volumetric differences (VD) were calculated. There were no significant differences found between the RPS volumes obtained using manual segmentation and ENet (p-value = 0.935), manual segmentation and ERFNet (p-value = 0.544), or ENet and ERFNet (p-value = 0.119). The sensitivity, PPV, DSC, VOE, and VD for ENet and ERFNet were 91.54% and 72.21%, 89.85% and 87.00%, 90.52% and 74.85%, 16.87% and 36.85%, and 2.11% and -14.80%, respectively. By using a dedicated GPU, ENet took around 15 s for segmentation versus 13 s for ERFNet. In the case of CPU, ENet took around 2 min versus 1 min for ERFNet. The manual approach required approximately one hour per segmentation. In conclusion, fully automatic deep learning networks are reliable methods for RPS volume assessment. ENet performs better than ERFNet for automatic segmentation, though it requires more time.

Safety and efficacy of pazopanib as a second-line treatment and beyond for soft tissue sarcomas: A real-life tertiary-center experience in the MENA region

INTRODUCTION

Sarcomas are uncommon malignancies. No advances have been recently achieved despite multiple efforts. Pazopanib is a safe and effective tyrosine kinase inhibitor used in managing soft tissue sarcomas (STS) after chemotherapy failure. However, its use is limited in developing countries and no efficacy data exist from our region. We aimed to study the efficacy of pazopanib in our population, characterized by response rates of patients with chemotherapy-refractory advanced STS receiving pazopanib. Secondary endpoints included progression-free survival (PFS), overall survival (OS) and toxicity profile.

MATERIALS AND METHODS

15 patients (age≥18 year) diagnosed with advanced STS, refractory to first-line chemotherapy, receiving pazopanib as ≥second-line therapy in one tertiary center in Lebanon were included between January 1st, 2014 and October 31st, 2018. Patient and disease characteristics, disease evaluation, as well as tolerance to treatment, were extracted from charts retrospectively. Statistical analysis was done using SPSS version 24.

RESULTS

The mean age was 48.6 [19-66] years. Eleven patients (73.3%) received pazopanib in second-line, whereas four patients (26.7%) received it in third-line. Thirteen patients (86.7%) progressed, and two patients (13.3%) had stable disease. The median PFS was three months [1-19] and the mean OS was 25.4 months [17.2-33.6]. Five patients required dose-reductions due to poor tolerance.

CONCLUSION

Conclusions cannot be drawn due to small patient numbers. However, given the 3-month PFS, 13% of patients maintaining stable disease, and tolerable safety profile, it is reasonable to incorporate pazopanib in STS treatment. More focused studies with larger patient populations need to be done in Lebanon.

Multifocal retroperitoneal sarcoma

Introduction. Retroperitoneal sarcomas comprise a small proportion of all soft tissue sarcomas, and multiple factors influence their clinical behavior. Histopathological type and grade as well as complete surgical resection especially on the first operative attempt are well recognized as the main prognostic factors. Multifocality is another prognostic factor, which compromises therapy and finally makes prognosis worse due to multiple adverse implications. Case Presentation. A rare case of a 65-year-old male patient suffering from a multifocal retroperitoneal liposarcoma successfully treated in our hospital is presented herein. Discussion. Also, general considerations for these tumors are discussed, and especially multifocality is underlined as an ominous sign of retroperitoneal sarcomas behavior. Despite multifocality, once again complete surgical excision remains the mainstay of treatment of these patients, as long as further systemic and local therapies do not provide durable results.

Retroperitoneal sarcomas- a challenging problem

Retroperitoneal sarcomas are relatively rare tumours and usually present in a locally advanced stage. Liposarcoma is the most common histopathology. If operable, surgery is the treatment of choice. The role of adjuvant chemotherapy or radiotherapy is not yet defined. Advanced cases are treated by chemotherapy. The prognosis is poor in patients with positive resection margins, high-grade tumours and recurrent tumours.

Focus on the tumour periphery in MRI evaluation of soft tissue sarcoma: infiltrative growth signifies poor prognosis

Purpose. Infiltrative microscopical peripheral growth of soft tissue sarcomas (STS) has been shown to be of prognostic importance and preoperative risk stratification could individualize neoadjuvant treatment. Patients and methods. We assessed peripheral tumour growth pattern on preoperative MRI from 78 STS. The findings were correlated to histopathology and to outcome. Results. The MRI-based peripheral tumour growth pattern was classified as pushing in 34 tumours, focally infiltrative in 25, and diffusely infiltrative in 19. All tumours with diffuse infiltration on MRI also showed microscopical infiltration, whereas MRI failed to identify infiltration in two-thirds of the microscopically infiltrative tumours. Diffusely infiltrative growth on MRI gave a 2.5 times increased risk of metastases (P = .01) and a 3.7 times higher risk of local recurrence (P = .02). Discussion. Based on this observation we suggest that MRI evaluation of STS should focus on the peripheral tumour growth pattern since it adds prognostic information of value for decisions on neoadjuvant therapies.

Retroperitoneal sarcomas

Retroperitoneal sarcomas are rare neoplasms. CT or MR imaging is performed in patients with these tumors to detect local extent and distant metastases of the tumor and for preoperative surgical planning. Most sarcomas cannot be characterized as to cell type with CT or MR, with the exceptions being liposarcomas and intracaval leiomyosarcomas. Similarly histological grading cannot be made definitively with imaging alone, the exception being liposarcoma since well differentiated liposarcomas contain more macroscopic fat than do less differentiated liposarcomas. After surgery, follow up imaging with CT or MR and careful scrutiny of the tumor bed and resection site are essential to detect early recurrences, which can often be managed with re-resection.

Musculoskeletal system

Diagnostic imaging has played a major role in the evaluation of patients with cancers of the bone and soft tissue. The imaging modalities have included radiography, computed tomography, magnetic resonance imaging, and bone scintigraphy. Current experience suggests that functional imaging with positron emission tomography (PET) and [F-18]fluorodeoxyglucose (FDG) may also have an important role in the imaging evaluation of patients with bone and soft tissue sarcoma, including guiding biopsy, detecting local recurrence in amputation stumps, detecting metastatic disease, predicting and monitoring response to therapy, and assessing for prognosis. Prospective studies with large patient groups will be essential to define the exact diagnostic role of FDG PET in this clinical setting, which should also include an evaluation of the cost-effectiveness and the short-term and long-term benefits in clinical decision making and management. In this article, we review the diagnostic utility of dedicated PET and PET combined with computed tomography imaging system in the evaluation of patients with bone and soft tissue malignancies.