Fluorodeoxyglucose positron emission tomography with computed tomography detects greater metabolic changes that are not represented by plain radiography for patients with osteonecrosis of the jaw.

PURPOSE: Imaging is important to identify subclinical changes and for treatment planning in patients with osteonecrosis of the jaw (ONJ) exposed to antiresorptive therapy. The aim of this study was to compare the findings at radiography with those at fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) for patients with ONJ related to antiresorptive therapy. MATERIALS AND METHODS: A cross-sectional retrospective analysis of patients with clinically identified ONJ lesions of the mandible was performed. Two imaging modalities were evaluated for each patient: plain radiography (ie, panoramic or periapical) and FDG PET/CT with 1-mm sections. Outcome variables for the radiographic findings were osteolytic and osteosclerotic bone changes. Outcome variables for FDG PET/CT images were localization of FDG uptake. Maximum standard uptake values (SUVmax) of abnormal FDG jaw uptake were recorded, in addition to the mean SUV of the contralateral normal mandible, and used to calculate the target-to-background ratio. Radiographic changes and FDG uptake were classified as local (ie, corresponding to exposed cortical bone) or diffuse (ie, local changes and changes extending beyond the margins of exposed bone) for each imaging technique. Local and diffuse changes detected by each imaging modality were described and the difference in detection was compared with the McNemar test. RESULTS: Twenty-three patients with 25 clinically identified ONJ lesions were analyzed using radiography and FDG PET/CT. Differences were found in how radiography and FDG PET/CT detect local and diffuse changes associated with ONJ. Radiography showed local changes in 17 patients (68%), diffuse changes in 3 patients (12%), and no changes in 5 patients (20%), whereas FDG PET/CT imaging showed local changes in 17 patients (68%) and diffuse changes in 8 patients (32%). The McNemar test indicated that FDG PET/CT imaging was less likely to miss a lesion (P < .001). Mean SUVmax was 6.59, and the mean target-to-background ratio was 5.37. CONCLUSION: The results of this study show that FDG PET/CT detects local and diffuse metabolic changes that may not be represented by plain radiography for patients with ONJ related to antiresorptive therapy. The target-to-background ratio allowed the discrimination between ONJ lesions and background changes. Future studies are necessary to determine whether FDG PET/CT can determine risk and facilitate management of ONJ.

Initial experience with FDG-PET/CT in the evaluation of breast cancer.

PURPOSE: We retrospectively reviewed FDG-PET/CT images in patients with breast cancer to determine whether PET/CT improved the level of diagnostic confidence as compared with PET and to compare PET/CT and CT findings at the location of suspected malignancies. METHODS: The study included 75 patients with known breast cancer. The initial PET/CT study for each patient was retrospectively reviewed to determine whether improved diagnostic confidence (IDC) regarding lesion localization and characterization was observed with PET/CT as compared with PET alone. PET/CT and CT findings were compared regarding lesion characterization and staging in 69 of the 75 patients, and in the case of discordant findings, comparison with histological or informative follow-up results was also performed. RESULTS: Fifty of the 75 patients exhibited increased FDG uptake in a total of 95 regions. In the comparison of PET/CT and PET, PET/CT resulted in IDC in 30 (60%) of these 50 patients and in 52 (55%) of the 95 regions. In the comparison between PET/CT and CT in 69 patients, PET/CT demonstrated a significantly better accuracy than CT (P<0.05). PET/CT showed definitely positive findings in 60 regions with malignancies, among which CT exhibited positive findings in 43 (72%). PET/CT and CT accurately staged 59 (86%) and 53 (77%) of the 69 patients, respectively. CONCLUSIONS: PET/CT added incremental diagnostic confidence to PET in more than 50% of patients and regions with increased FDG uptake. PET/CT accurately detected more regions with malignancies than did CT. This initial evaluation suggests that PET/CT is preferable to PET or CT in the diagnosis of breast cancer.

"USA-Fat": prevalence is related to ambient outdoor temperature-evaluation with 18F-FDG PET/CT.

UNLABELLED: Increased (18)F-FDG activity in fatty tissue has previously been reported with PET/CT. We previously named this activity uptake in supraclavicular area fat ("USA-Fat"). We and others have speculated that this uptake exists in metabolically active brown adipose tissue (BAT). Such tissue might be expected to have varying metabolic activity depending on the ambient temperature. The purpose of this study was to evaluate the frequency of USA-Fat and its relationship to the outdoor temperature. METHODS: Between July 2001 and June 2002, 1,017 consecutive whole-body scans were obtained with a PET/CT scanner and (18)F-FDG for clinical patients. PET images were reviewed for the presence of USA-Fat. RESULTS: USA-Fat was observed in 68 scans obtained from 62 patients (51 female and 11 male). The incidence of USA-Fat was highest, at 13.7%, in January through March, while outside temperatures were low, and was significantly lower, at 4.1%, during the rest of the year. CONCLUSION: The incidence of USA-Fat is clearly increased during the cooler period of the year. This finding suggests that stimulation by cold temperatures increases the frequency with which USA-Fat occurs, supporting underlying BAT as the etiology for this activity.