Regardless of presentation and clinical history, cross-sectional imaging, in the form of computed tomography (CT) and/or magnetic resonance imaging (MRI) is essential in any approach to sarcoma.1
CT is recommended as the first line investigation. High resolution, thin slices CT scan with coronal and sagittal MPR capability is desired, with both intravenous and oral contrast medium administration.2Intravenous contrast enhanced helical CT scan of the abdomen and pelvis is the minimum investigation to be performed. This allows for characterisation of the mass, local staging, delineation of the margins and differentiation from adjacent organs and vascular structures. Differentiation between retroperitoneal, intra-peritoneal, and visceral origin is essential.1-4
A CT scan of the thorax to assess for any lung metastatic disease and other intrathoracic pathology can also be performed at the same time.1,3-6 In lieu of a CT thorax scan, a plain erect frontal chest radiograph may be obtained for screening.
MRI scans should be reserved to answer specific problems. With its superior tissue contrast resolution, MRI can be used to assess vascular and neural invasion and to characterise the solid, cystic and necrotic areas of the mass.1-5Scans with and without intravenous MRI contrast medium administration is recommended when this modality is employed.
Pre-operative core needle biopsy, if required, should be under CT guidance, with the track and targeted region determined after discussion with the surgical team. The National Comprehensive Cancer Network (NCCN) guidelines state that pre-resection biopsy is necessary in patients receiving pre-operative radiation therapy (RT) or chemotherapy; fine needle aspiration is generally insufficient to obtain material sufficient to make a diagnosis, given multiple sarcoma subtypes and a variety of histological and fluorescencein situhybridisation markers that can be brought to bear on diagnosis (see below on biopsy guidelines).5
The utility of whole body MRI and positron emission tomography (PET) CT imaging is still being evaluated for both staging and post-treatment follow-up, with research still ongoing.