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.

Interest in bone marrow scanning has been renewed as the result of the development of radiopharmaceuticals for evaluating specific aspects of bone marrow anatomy, physiology and pathology. This article provides a brief review of bone marrow structure, blood flow and function essential to the understanding of basic principles of bone marrow radionuclide imaging. The prospects and limitations of imaging haematopoietic bone marrow in man using indium 111 chloride, technetium-99m (99mTc)-labelled microcolloid or 99mTc-labelled monoclonal antigranulocytic and antimyelocytic antibodies are discussed in more detail. The technical aspects of bone marrow scintigraphy are presented. Results of more recent studies evaluating bone marrow scanning in circulatory, inflammatory and in systemic haematological disorders are summarized. Special attention is paid to the concept of bone marrow micrometastases and its implications for the follow-up of patients with malignant tumours. Recent results suggest that immunoscintigraphy of bone marrow may provide a novel and sensitive approach for establishing the presence and extent of bone marrow infiltration.

Summary Aim of this study was to investigate, how often TNM staging is changed in patients with malignant pleural mesothelioma (MPM) by the application of integrated PET-CT compared to computed tomography alone and how often these changes are clinically relevant. Patients, methods: We studied 17 patients (68 ? 6 years, 8 women) with MPM. Integrated PET-CT scan and histological confirmation were performed in all patients. Results: Final histological diagnosis confirmed 9 epithelial type, 2 sarcomatoid type and 6 biphasic type MPM. Mean standardized uptake value (SUV) was 5.9 ? 1.9 in epithelial MPM and 15.1 ? 10.2 in sarcomatoid MPM. CT and PET-CT revealed discordances in 8/17 (47%) patients in TNM classification with 4/8 (50%) being clinically relevant. PET-CT led to downstaging in 5 (29%) and upstaging in 3 (18%) patients. Mean survival time tended to be higher in the subgroup of patients with lower mean SUV. Conclusions: PET-CT seems to be a valuable tool in staging of MPM and leads to discordant findings in almost every second patient compared to CT alone. In many cases these differences are clinically relevant and have therapeutic consequences.

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IntroductionEarly diagnosis and correct staging are crucial for the stage-appropriate therapy of lung cancer as both reflect patients prognosis. The primary detection of lymph node metastases or distant metastases is decisive in planning patients management. Staging of non-small-cell lung cancer (NSCLC) is governed by the International System for Staging Lung Cancer, most recently revised in 1997 [1,2]. Studies have shown a very clear relationship between tumor stage and survival. Thus, patients with small tumors but no nodal or distant spread have a 60 ± 80 % five-year survival, whereas patients with disseminated metastatic disease have a less than 5 % chance of five-year survival [3].Computed tomography (CT) is one of the most common staging investigations performed and has been widely investigated. In the assessment of nodal stage, particularly for the mediastinum, the standard criterion for an involved mediastinal lymph node has varied but generally is regarded as a lymph node > 1 cm in the short axis and transverse plane [4]. Central to this rule is that malignant involvement of a lymph node causes an enlargement of respective lymph node and that there are no other causes for mediastinal lymph node enlargement [4]. This, however, is not always the case and, in one series, it was found that 13% of normal-sized lymph nodes (> 1 cm in diameter) contained malignant cells, while 25% of lymph nodes with diameters of 1.0 ± 1.9 cm had tumor, and only 37% of lymph nodes > 2 cm contained Abstract Background: Mediastinal lymph node staging is essential to determine treatment options in patients with NSCLC. Positron emission tomography (PET) detects increased glucose uptake in malignant tissue using the glucose analogue 2-[ 18 F]fluoro-2-deoxy-D-glucose (FDG). Patients and Methods: In the present study were evaluated 155 patients with focal pulmonary tumors who underwent both preoperative computed tomography (CT) and FDG-PET scanning (116 malignant and 39 benign lesions). Results: Findings in 155 patients included 116 malignant and 39 benign lesions. For N-staging, FDG-PET showed a sensitivity of 88%, a specificity of 91%, and an accuracy of 89%. Corresponding figures for CT were 77%, 76%, and 77%, respectively. Conclusions: FDG-PET is an effective, noninvasive method for staging thoracic lymph nodes in patients with lung cancer and is superior to CT scanning in the assessment of hilar and mediastinal nodal metastases. With regard to operability, FDG-PET could differentiate reliable between patients with N1/N2 disease and those with unresectable N3 disease.