Contemporary imaging in sarcoma

Descriptive analysis of MRI functional changes occurring during reduced dose radiotherapy for myxoid liposarcomas

OBJECTIVES

Myxoid liposarcomas (MLS) show enhanced response to radiotherapy due to their distinctive vascular pattern and therefore could be effectively treated with lower radiation doses. This is a descriptive study to explore the use of functional MRI to identify response in a uniform cohort of MLS patients treated with reduced dose radiotherapy.

METHODS

10 patients with MLS were imaged pre-, during, and post-radiotherapy receiving reduced dose radiotherapy and the response to treatment was histopathologically assessed post-radiotherapy. Apparent diffusion coefficient (ADC), T2* relaxation time, volume transfer constant (Ktrans), initial area under the gadolinium curve over 60 s (IAUGC60) and (Gd) were estimated for a central tumour volume.

RESULTS

All parameters showed large inter- and intrasubject variabilities. Pre-treatment (Gd), IAUGC60 and Ktrans were significantly different between responders and non-responders. Post-radiotherapy reductions from baseline were demonstrated for T2*, (Gd), IAUGC60 and Ktrans for responders. No statistically significant ADC differences were demonstrated between the two response groups. Significantly greater early tumour volume reductions were observed for responders.

CONCLUSIONS

MLS are heterogenous lesions, characterised by a slow gradual contrast-agent uptake. Pre-treatment vascular parameters, early changes to tumour volume, vascular parameters and T2* have potential in identifying response to treatment. The delayed (Gd) is a suitable descriptive parameter, relying simply on T1 measurements. Volume changes precede changes in MLS functionality and could be used to identify early response.

ADVANCES IN KNOWLEDGE

MLS are are characterised by slow gradual contrast-agent uptake. Measurement of the delayed contrast-agent uptake (Gd) is simple to implement and able to discriminate response.

Imaging of Soft Tissue Tumors

Differentiation of malignant from benign soft tissue tumors is challenging with imaging alone, including that by magnetic resonance imaging and computed tomography. However, the accuracy of this differentiation has increased owing to the development of novel imaging technology. Detailed patient history and physical examination remain essential for differentiation between benign and malignant soft tissue tumors. Moreover, measurement only of tumor size based on Response Evaluation Criteria In Solid Tumors criteria is insufficient for the evaluation of response to chemotherapy or radiotherapy. Change in metabolic activity measured by ¹⁸F-fluorodeoxyglucose positron emission tomography or dynamic contrast enhanced-derived quantitative endpoints can more accurately evaluate treatment response compared to change in tumor size. Magnetic resonance imaging can accurately evaluate essential factors in surgical planning such as vascular or bone invasion and "tail sign". Thus, imaging plays a critical role in the diagnosis and treatment of soft tissue tumors.

Optimal maximum duration for delaying salvage operation when recurrence of retroperitoneal liposarcoma is suspected: a single-center study

BACKGROUND

This study was designed to identify the optimal maximum duration for delaying salvage operation when recurrence of retroperitoneal liposarcoma (LPS) is suspected.

METHODS

Patients who underwent salvage operation at Samsung Medical Center for recurrent retroperitoneal LPS from January 2000 to December 2015 were reviewed. The time interval between recurrence and operation for recurrence was divided by 1, 2 or 3 months. A Cox proportional-hazards model was used to analyze factors related to disease-free survival along with recurrence-to-operation interval divided by 1, 2 or 3 months.

RESULTS

The 1-, 3-, and 5-year disease-free survival rates were 43.2%, 15.6% and 13.4%, respectively. FNCLCC grade (p = 0.023) and recurrence-to-operation interval divided by 3 months (p = 0.003) were significant factors associated with recurrence. FNCLCC grade 2 (HR 1.940, CI 0.935-4.026, p = 0.238) and grade 3 (HR 4.049, CI 1.767-9.281, p = 0.007) showed increased risk compared to grade 1. Patients who underwent salvage operation more than 3 months after recurrence showed significantly increased risk of recurrence compared to patients within 3 months (HR 2.724, CI 1.391-5.337, p = 0.003).

CONCLUSIONS

Based on our analysis of recurrence-free survival, salvage operation can be delayed for less than 3 months when recurrence is suspected. A short-term follow-up imaging study should be performed within this period.

Musculoskeletal Sarcoma: Update on Imaging of the Post-treatment Patient

Post-treatment imaging of musculoskeletal sarcoma remains challenging, but newer imaging techniques are improving our ability to recognize both local and distant recurrence and accurately distinguish local recurrence from post-treatment change. We review recent advances in dynamic contrast-enhanced magnetic resonance imaging, diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient mapping and positron emission tomography/computed tomography in the post-treatment follow-up of musculoskeletal sarcoma. We also describe our multidisciplinary sarcoma team approach to patient care and the essential role of the radiologist in the clinical follow-up scheme.

Synergistic role of simultaneous PET/MRI-MRS in soft tissue sarcoma metabolism imaging

The primary objective of this study was to develop and validate simultaneous PET/MRI-MRS as a novel biological image-guided approach to neoadjuvant radiotherapy (RT) and/or chemoradiation (chemoRT) in soft tissue sarcomas (STS). A patient with sarcoma of the right thigh underwent PET/MRI scan before and after neoadjuvant (preoperative) radiotherapy. The magnetic resonance imaging (MRI) and 2-deoxy-2-[fluorine-18]-fluoro-D-glucose-Positron Emission Tomography ((18)F-FDG-PET) scans were performed simultaneously. In the post-radiation scan, magnetic resonance spectroscopy (MRS) was subsequently acquired with volume of interest positioned in a residual hyper-metabolic region detected by PET. Post-radiation PET/MRI showed a residual T2-hyperintense mass with significantly reduced (18)F-FDG-uptake, compatible with near complete response to radiotherapy. However, a small region of residual high (18)F-FDG uptake was detected at the tumor margin. MRS of this region had similar metabolite profile as normal tissue, and was thus considered false positive on PET scan. Pathology results were obtained after surgery for confirmation of imaging findings.

Biopsy and the diagnostic evaluation of musculoskeletal tumours: critical but often missed in the 21st century

Bone and soft-tissue sarcomas are rare and heterogeneous malignancies arising from tissues of mesenchymal origin. Treatment planning is informed by accurate diagnosis for which biopsy is the diagnostic standard. Biopsy in the setting of suspected malignancy is a technically challenging procedure that should only be performed at specialist institutions. Without the requisite expertise, they can compromise the viability of reconstructive procedures and may make necessary amputation to achieve adequate surgical margins. The risk of complications arising from the procedure must be minimized and therefore biopsy should always be preceded by imaging. There must be no attempt at biopsy or excision prior to referral if there is any suspicion of malignancy. Patients with suspected bone and soft-tissue tumours are best evaluated and treated at specialist sarcoma centres under the care of expert multidisciplinary teams. Prompt referral to a specialist sarcoma centre should always be made prior to biopsy for any suspicious mass that is painful, progressively increasing in size, greater than 5 cm in diameter, deep to deep fascia or recurs following inadvertent excision.

Retroperitoneal liposarcoma: current insights in diagnosis and treatment

Retroperitoneal liposarcoma (RLS) is a rare, biologically heterogeneous tumor that present considerable challenges due to its size and deep location. As a consequence, the majority of patients with high-grade RLS will develop locally recurrent disease following surgery, and this constitutes the cause of death in most patients. Here, we review current insights and controversies regarding histology, molecular biology, extent of surgery, (neo)adjuvant treatment, and systemic treatment including novel targeted agents in RLS.

Contrast-enhanced color Doppler ultrasonography increases diagnostic accuracy for soft tissue tumors

Resolution of ultrasonography (US) has undergone marked development. Additionally, a new-generation contrast medium (Sonazoid) used for US is newly available. Contrast-enhanced US has been widely used for evaluating several types of cancer. In the present study, we evaluated the ability of color Doppler US (CDUS) and Sonazoid to differentiate between benign and malignant soft tissue tumors. A total of 180 patients (87 male, 93 female) were enrolled in the present study. The patient ages ranged from 1 to 91 years (mean 58.1±20.0 years). The maximum size, depth, tumor margins, shape, echogenicity and textural pattern were measured on gray-scale images. CDUS was used to evaluate the intratumoral blood flow with and without Sonazoid. Peak systolic flow velocity (Vp), mean flow velocity (Vm), resistivity index (RI) and pulsatility index (PI) of each detected intratumoral artery were automatically calculated with power Doppler US (PDUS). The present study included 118 benign and 62 malignant tumors. Statistical significances were found in size, depth, tumor margin and textural pattern but not in shape or echogenicity on gray-scale images. Before Sonazoid injection, CDUS findings showed 55% sensitivity, 77% specificity and 69% accuracy, whereas contrast-enhanced CDUS showed 87% sensitivity, 68% specificity and 74% accuracy. There were no statistically significant differences between malignant and benign tumors regarding the mean Vp, Vm, RI and PI values determined on PDUS. In conclusion, contrast-enhanced CDUS proved to be a reliable diagnostic tool for detecting malignant potential in soft tissue tumors.

[Consensus diagnosis and therapy of soft tissue sarcoma]

Soft tissue sarcomas are heterogeneous tumours and relatively uncommon. There have been advances over the past years concerning pathology, clinical behaviour, diagnosis strategies and the treatment. To summarize these advances as well as making it public is one of the goals of the following consensus guidelines. But why do we need special guidelines for Austria? There are international guidelines published by the European Society of Medical Oncology (ESMO) and the National Comprehensive Cancer Network (NCCN). The cause is that we need an explanation of the matrix the ESMO and the NCCN gave according to our clinical practice, the local requirements and facilities in Austria. The following recommendations were drawn up following a consensus meeting of sarcoma specialists from the three high volume centres located at the medical universities in Austria. All fields of involved physicians from diagnosis to therapy worked together to know that soft tissue sarcomas are an interdisciplinary challenge and multimodal treatment is essential. For this reason, these guidelines not only explain but also give the state of the art and clear recommendations. One of the most important guidelines is that any patient with a suspected soft tissue sarcoma should be referred to one of the three university centres and managed by a specialist sarcoma multidisciplinary team. We hope that the consensus is helpful for the clinical practice and improves the quality of care for patients with soft tissue sarcomas in Austria.

Imaging pediatric bone sarcomas

Primary malignant bone tumors are rare and account for about 6% of all new pediatric cancer cases per year in the United States. Identification of the lesion not uncommonly occurs as a result of imaging performed for trauma. Clinical and standard imaging characteristics of the various tumor types are evolving in concert with treatment advancements and clinical trial regimens. This article reviews the 3 most common pediatric bone sarcomas-osteosarcoma, Ewing sarcoma, and chondrosarcoma-and their imaging as applicable to contemporary disease staging and monitoring, and explores the roles of evolving imaging techniques.

Impact of abdominopelvic CT on Ewing sarcoma management

RATIONALE AND OBJECTIVES

Abdominopelvic computed tomography (APCT) is often performed in patients with skeletal Ewing sarcoma family of tumors during initial staging and for subsequent clinical indications, such as metastasis surveillance; however, its clinical impact is unknown. The purpose of this study was to evaluate whether these computed tomographic examinations alter oncologic management and therefore patient outcomes.

MATERIALS AND METHODS

One hundred eight consecutive patients with skeletal Ewing sarcoma family of tumors seen from 1985 to 2008 were retrospectively reviewed to identify imaging workup, pathology, primary site, evidence of metastatic disease, and patient outcomes. Data were analyzed using Wilcoxon's rank sum tests.

RESULTS

Sixty-five of the 108 patients (60%) underwent 342 abdominopelvic computed tomographic examinations during a mean follow-up period of 8.9 years. During this time period, only one of the 65 patients (1.5%) who underwent APCT was discovered to have abdominal metastatic disease. There was no significant difference in the incidence of metastatic disease to the skeleton or chest between the groups without and with APCT (P = .10). There were 26 pelvic and lumbosacral primaries (24%) and 82 limb primaries (76%). Subgroup analysis performed on the 82 patients with limb primaries without (n = 36) and with (n = 46) APCT showed no significant differences in metastatic incidence to the skeleton or chest (P = .14).

CONCLUSIONS

This study indicates that APCT, associated with increased radiation exposure and health expenditure, has a limited role in initial staging and follow-up in patients with skeletal Ewing sarcoma, particularly in patients with limb primaries.