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Bone metastasis is an important factor for the treatment and prognosis of breast cancer patients. Whole-body bone scintigraphy (WBBS) can evaluate skeletal metastases, and 18F-FDG PET/CT seems to exhibit high specificity and accuracy in detecting bone metastases. However, there is a limitation of 18F-FDG PET in assessing sclerotic bone metastases because some lesions may be undetectable. Recent studies showed that 18F-fluoride PET/CT is more sensitive than WBBS in detecting bone metastases. This study aims to evaluate the usefulness of 18F-fluoride PET/CT by comparing it with WBBS and 18F-FDG PET/CT in breast cancer patients with osteosclerotic skeletal metastases.Nine breast cancer patients with suspected bone metastases (9 females; mean age ± SD, 55.6 ± 10.0 years) underwent 99mTc-MDP WBBS, 18F-FDG PET/CT and 18F-fluoride PET/CT. Lesion-based analysis of five regions of the skeletons (skull, vertebral column, thoracic cage, pelvic bones and long bones of extremities) and patient-based analysis were performed.18F-fluoride PET/CT, 18F-FDG PET/CT and WBBS detected 49, 20 and 25 true metastases, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of 18F-fluoride PET/CT were 94.2 %, 46.3 %, 57.7 % and 91.2 %, respectively. Most true metastatic lesions on 18F-fluoride PET/CT had osteosclerotic change (45/49, 91.8 %), and only four lesions showed osteolytic change. Most lesions on 18F-FDG PET/CT also demonstrated osteosclerotic change (17/20, 85.0 %) with three osteolytic lesions. All true metastatic lesions detected on WBBS and 18F-FDG PET/CT were identified on 18F-fluoride PET/CT.18F-fluoride PET/CT is superior to WBBS or 18F-FDG PET/CT in detecting osteosclerotic metastatic lesions. 18F-fluoride PET/CT might be useful in evaluating osteosclerotic metastases in breast cancer patients.

Malignant fibrous histiocytoma (MFH) is the most common soft tissue tumor which often occurs in the extremities and the retroperitoneum. Primary mediastinal MFH is rare; thus, findings on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) of mediastinal MFH have not been reported yet. We report herein the case of a 64-year-old man who was presented with a superior mediastinal mass. The mass showed intense 18F-FDG uptake with central metabolic defect on PET/CT. The maximum standardized uptake value was 17.4. After tumor removal via median sternotomy, an MFH of the storiform-pleomorphic type was diagnosed on histopathologic examination. We present the first report of 18F-FDG PET/CT imaging of MFH in the superior mediastinum.Malignant fibrous histiocytoma (MFH) is the most common soft tissue tumor which often occurs in the extremities and the retroperitoneum. Primary mediastinal MFH is rare; thus, findings on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) of mediastinal MFH have not been reported yet. We report herein the case of a 64-year-old man who was presented with a superior mediastinal mass. The mass showed intense 18F-FDG uptake with central metabolic defect on PET/CT. The maximum standardized uptake value was 17.4. After tumor removal via median sternotomy, an MFH of the storiform-pleomorphic type was diagnosed on histopathologic examination. We present the first report of 18F-FDG PET/CT imaging of MFH in the superior mediastinum.

Abstract: Purpose: Gastric signet ring cell carcinoma (GSRC) is known to have low fluorodeoxyglucose (FDG) uptake. The aim of the study was to investigate the relation between FDG uptake and glucose transporter (GLUT)-1 expression and clinicopathologic parameters in cases of GSRC. Materials and Methods: Forty patients (28 men, mean age 54 ± 12 years) with histologically confirmed GSRC who underwent pre-operative [18F]FDG PET/CT were enrolled. Maximum standardized uptake values (SUVmax) were compared with clinicopathologic parameters and GLUT-1 expression. Cases were divided based on GLUT-1 expression in tumor tissues into a membranous group (n = 17) and a cytoplasmic group (n = 23). Results: Mean SUVmax was significantly higher in the membranous group than in the cytoplasmic group (6.06 ± 2.79 vs. 3.67 ± 1.54, P = 0.03). Gastric wall invasion, depth of invasion, extent of LN metastasis, overall stage, and tumor size were found to be related to SUVmax. On the other hand, age, sex, and the presence of distant metastasis were not related to SUVmax. Multivariate analysis revealed that membranous GLUT-1 expression and the extent of LN metastasis independently predicted high FDG uptake. Conclusions: This study demonstrates that high FDG uptake is mediated by membranous GLUT-1 expression in GSRC.