Fluorodeoxyglucose positron emission tomography of soft tissue tumours: is a non-invasive determination of biological activity possible?

Abstract

Since musculoskeletal tumours comprise a large heterogeneous group of entities with different biological behaviour, clinical diagnosis of such lesions can be very difficult. The aim of this prospective study was to assess the usefulness of 2-[F-18]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in the non-invasive evaluation of soft tissue tumours. One hundred and two patients with suspected soft tissue neoplasms were investigated by FDG-PET. The uptake of FDG was evaluated semiquantitatively by determining the tumour to background ratio (TBR). All patients underwent biopsy, resulting in the histological detection of 39 high-grade sarcomas, 16 intermediate-grade sarcomas, 11 low-grade sarcomas, 25 benign tumours, 10 tumour-like lesions such as spontaneous myositis ossificans (n = 6) and one non-Hodgkin lymphoma. All lesions except for two lipomas disclosed an increased FDG uptake. Sarcomas showed significantly higher TBR values than latent or active benign lesions (P<0.001) and aggressive benign lesions (P<0.05). Using a TBR cut-off level of 3.0 for malignancy, sensitivity of FDG-PET was 97.0%, specificity 65.7% and accuracy 86. 3%. From our data there are three main conclusions: (1) Except for patients with pseudotumoral myositis ossificans, lesions with a TBR >3 were sarcomas (91.7%) or aggressive benign tumours (8.3%). (2) Tumours with a TBR <1.5 were latent or active benign lesions, exclusively. (3) The group with intermediate TBR values (<3 and >1. 5) comprised primarily latent or active benign lesions, but also four aggressive benign tumours and two low-grade sarcomas. Our data suggest that FDG-PET represents a useful tool for the evaluation of the biological activity of soft tissue neoplasms.

Detection and Grading of Soft Tissue Sarcomas of the Extremities with 18F-3′-Fluoro-3′-Deoxy-l-Thymidine

“…Most previous studies for detecting sarcomas have been performed with 18 F-fluoro-2Ј-deoxy-D-glucose-PET (FDG-PET) and have recently been critically reviewed in two meta-analyses (31,32). The sensitivity of FDG-PET for detecting primary and recurrent sarcomas varies from 88 to 92%, and specificity varies form 73 to 87% (31,32).…”

“…Therefore, a PET-tracer that would reflect proliferation, could have the potential to visualize the grading of STS. For this purpose, 18 F-fluoro-3Ј-deoxy-3Ј-L-fluorothymidine (FLT) was developed (33,39). This pyrimidine analog is phosphorylated by the enzyme thymidine kinase 1, which leads to intracellular trapping (33).…”

“…1 The whole body 18 F-3Ј-fluoro-3Ј-deoxy-L-thymidine-positron emission tomography (FLT-PET) image of patient 16. Small arrows, physiological uptake of FLT can be seen in the bone marrow of the pelvis, ribs, and vertebrae; in the bones of the shoulder; in the liver; and in the bladder.…”

“…Several years ago 18 F-3Ј-fluoro-3Ј-deoxy-L-thymidine (FLT) was introduced as PET tracer (33). This tracer has theoretical advantages over the currently used FDG, because no uptake in inflammatory cells is anticipated.…”

“…During the last decade, the value of positron emission tomography (PET) in STS with several tracers, especially [ 18 F]fluoro-2Ј-deoxy-Dglucose (FDG), has been investigated (10 -16). However, the current potential of FDG-PET in the detection and/or grading is still unknown (10,11,15,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32).…”