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Purpose: We investigated whether (131)I whole-body scintigraphy could predict functional changes in salivary glands after radioiodine therapy., Methods: We evaluated 90 patients who received initial high-dose (≥3.7 GBq) radioiodine therapy after total thyroidectomy. All patients underwent diagnostic (DWS) and post-ablation (TWS) (131)I whole-body scintigraphy. Visual assessment of salivary radioiodine retention on DWS and TWS was used to divide the patients into two types of groups: a DWS+ or DWS- group and a TWS+ or TWS- group. Salivary gland scintigraphy was also performed before DWS and at the first follow-up visit. Peak uptake and %washout were calculated in ROIs of each gland. Functional changes (Δuptake or Δwashout) of salivary glands after radioiodine therapy were compared between the two groups., Results: Both peak uptake and the %washout of the parotid glands were significantly lower after radioiodine therapy (all p values <0.001), whereas only the %washout were significantly reduced in the submandibular glands (all p values <0.05). For the parotid glands, the TWS+ group showed larger Δuptake and Δwashout after radioiodine therapy than did the TWS- group (all p values <0.01). In contrast, the Δuptake and Δwashout of the submandibular glands did not significantly differ between the TWS+ and TWS- groups (all p values >0.05). Likewise, no differences in Δuptake or Δwashout were apparent between the DWS+ and DWS- groups in either the parotid or submandibular glands (all p values >0.05)., Conclusion: Salivary gland radioiodine retention on post-ablation (131)I scintigraphy is a good predictor of functional impairment of the parotid glands after high-dose radioiodine therapy.

Purpose: 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 (18)F-FDG PET/CT seems to exhibit high specificity and accuracy in detecting bone metastases. However, there is a limitation of (18)F-FDG PET in assessing sclerotic bone metastases because some lesions may be undetectable. Recent studies showed that (18)F-fluoride PET/CT is more sensitive than WBBS in detecting bone metastases. This study aims to evaluate the usefulness of (18)F-fluoride PET/CT by comparing it with WBBS and (18)F-FDG PET/CT in breast cancer patients with osteosclerotic skeletal metastases., Materials and Methods: Nine breast cancer patients with suspected bone metastases (9 females; mean age ± SD, 55.6 ± 10.0 years) underwent (99m)Tc-MDP WBBS, (18)F-FDG PET/CT and (18)F-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., Results: (18)F-fluoride PET/CT, (18)F-FDG PET/CT and WBBS detected 49, 20 and 25 true metastases, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of (18)F-fluoride PET/CT were 94.2 %, 46.3 %, 57.7 % and 91.2 %, respectively. Most true metastatic lesions on (18)F-fluoride PET/CT had osteosclerotic change (45/49, 91.8 %), and only four lesions showed osteolytic change. Most lesions on (18)F-FDG PET/CT also demonstrated osteosclerotic change (17/20, 85.0 %) with three osteolytic lesions. All true metastatic lesions detected on WBBS and (18)F-FDG PET/CT were identified on (18)F-fluoride PET/CT., Conclusion: (18)F-fluoride PET/CT is superior to WBBS or (18)F-FDG PET/CT in detecting osteosclerotic metastatic lesions. (18)F-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 (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-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 (18)F-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 (18)F-FDG PET/CT imaging of MFH in the superior mediastinum.

Purpose: We investigated the clinical significance of diffuse uptake in remaining thyroid after unilateral lobectomy for thyroid cancer., Methods: A total of 144 thyroid cancer patients who underwent (18)F-FDG PET/CT after lobectomy were enrolled in the present study. The PET/CT images were evaluated for the presence of diffuse (18)F-FDG uptake with maximum SUV (SUVmax) >2.0 in the residual thyroid and placed into one of two groups: with diffuse uptake and without diffuse uptake group. Clinical, laboratory, and PET/CT parameters in both groups were compared. Correlations between SUVmax of thyroid and available parameters were analyzed., Results: Forty-two of 144 patients (29.2%) had diffuse thyroid uptake (mean SUVmax: 3.2 ± 1.1). All patients with diffuse uptake and 96 (94.1%) without diffuse uptake were receiving thyroxine therapy (P = 0.09). Thyroid function tests showed that most patients were euthyroid status (78.6 vs. 85.3%, P = 0.36). TgAb levels were significantly higher in patients with diffuse uptake (338.0 ± 664.6 vs. 57.3 ± 46.4, P < 0.0001). Mean attenuation values in the diffuse uptake group were significantly lower (72.2 ± 15. vs. 97.0 ± 16.0, P < 0.0001). An inverse correlation was found between SUVmax and mean attenuation values of residual thyroid in all patients (r = -0.57, P < 0.0001) and subgroup with diffuse uptake (r = -0.31, P < 0.05)., Conclusion: In this study, diffuse (18)F-FDG uptake in the residual thyroid after unilateral lobectomy was a relatively frequent finding and may be associated with chronic thyroiditis. This uptake is not influenced by thyroid status or thyroxine therapy. The (18)F-FDG uptake is inversely correlated with mean attenuation value of thyroid.