Higher breast cancer conspicuity on dbPET compared to WB-PET/CT.

OBJECTIVES: The purpose of this study was to evaluate lesion detectability of a dedicated breast positron-emission tomography (dbPET) scanner for breast cancers with an updated reconstruction mode, comparing it to whole-body positron-emission tomography/computed tomography (WB-PET/CT). MATERIALS AND METHODS: A total of 179 histologically-proven breast cancer lesions in 150 females who underwent both WB-PET/CT and dbPET with 18F-fluorodeoxyglucose were retrospectively analyzed. The patient/breast/lesion-based sensitivities based on visual analysis were compared between dbPET and WB-PET/CT. For lesions visible on both PET images, SUVmax values of the tumors were measured, and tumor-to-background ratios (T/B ratios) of SUVmax were compared between the two scans. Subgroup analyses according to clinical tumor stage, histopathology and histological grade were also performed. RESULTS: Patient/breast/lesion-based sensitivities were 95%, 95%, and 92%, respectively, for dbPET, and 95%, 94%, and 88%, respectively, for WB-PET/CT. Mean±standard deviation SUVmax values of FDG-avid tumors were 13.0±9.7 on dbPET and 6.4±4.8 on WB-PET. T/B ratios were also significantly higher in dbPET than in WB-PET/CT (8.1±7.1 vs. 5.1±4.5). In the subgroup analysis, no significant differences in sensitivities between dbPET and WB-PET/CT were found. However, T/B ratios of dbPET were significantly higher than those of WB-PET/CT in cT1c, cT2, cT3, invasive cancer, invasive carcinoma of no special type, mucinous carcinoma and Grades 1-3. CONCLUSION: No significant differences in sensitivities were identified between dbPET using an updated reconstruction mode and WB-PET/CT; however, T/B ratios of dbPET were significantly higher than those of WB-PET/CT, indicating higher tumor conspicuity on dbPET.

Diagnostic performance of a novel dedicated breast PET scanner with C-shaped ring detectors.

BACKGROUND: A dedicated breast PET scanner with C-shaped detectors (C scanner) has been newly developed. The purpose of this study was to re-evaluate the diagnostic performance of high-resolution PET images with the new reconstruction conditions, obtained using this C scanner in breast cancer patients, and to compare the standardized uptake values (SUVs) of lesions obtained from the C scanner with those from whole-body PET/computed tomography (CT) (WB PET/CT). PATIENTS AND METHODS: A total of 159 female patients with known or suspected breast carcinomas (total 188 lesions: 172 invasive carcinomas; eight noninvasive ductal carcinomas in situ; eight benign lesions) were analysed. All patients underwent a WB PET/CT scan 1 h after the injection of fluorine-18 fluorodeoxyglucose, followed by breast scanning using the C scanner. Attenuation-corrected and scatter-corrected images were reconstructed with new parameters. RESULTS: Using the C scanner, 146 of 180 malignant lesions including five ductal carcinomas in situ were detected, 11 lesions were not detected, and the remaining 23 lesions were outside the field of view. The lesion-based sensitivity of the C scanner was 81.1%, and this was increased to 93.0% after excluding lesions outside the field of view; the sensitivity of WB PET/CT was 90.4%. The average maximum SUV of lesions obtained using the C scanner was 9.8±7.0, which was ∼1.6-fold larger than that obtained using WB PET/CT (6.1±4.2). CONCLUSION: There was no significant difference in breast cancer detectability in this population. The C scanner demonstrated ∼1.6-fold larger maximum SUV than WB PET/CT.

FDG uptake observed around the lumbar spinous process: relevance to Baastrup disease.

OBJECTIVE: In positron emission tomography (PET) with F-18-fluorodeoxyglucose (FDG), non-tumorous focal uptake is often observed around the lumbar spinous processes (LSPs). Close approximation of LSPs with sclerosis is often seen, which is called Baastrup disease. The aim of this study was to characterize this finding in terms of location and subjects' age and investigate the relation between PET and CT findings. METHODS: The PET/CT scans of 40 patients each in the fifth, sixth, seventh, eighth, and ninth decades were screened for FDG uptake around the LSPs from L1-2 through L5-S1. Patients with metastasis to the lumbar spine or recent chemotherapy or rheumatoid arthritis-related disease were excluded. Focal uptake greater than blood pool activity was considered positive. Positive uptake was compared among the ages and locations. We also evaluated the relationship between FDG uptake and CT morphology. RESULTS: Overall, focal uptake was observed in 122 LSPs in 71 patients. At least one positive uptake was seen in 9, 21, 15, 12, and 14 of 40 patients (16, 30, 30, 20, and 26 of 200 regions) in each age group of 40s through 80s, respectively (p = 0.12). As for the location, uptake around L1-2, L2-3, L3-4, L4-5, and L5-S1 was observed in 19, 22, 39, 35, and 7 regions, respectively (p < 0.01). There was no statistically significant difference in PET positivity among the five age groups, but positive uptake was predominantly seen in L3-4. Degeneration on CT was apparent in 58, 74, 108, 123, and 144 regions in each age group, respectively (p < 0.01), and in 38, 79, 131, 151, and 108 regions in each location, respectively (p < 0.01). The PET positive ratio was higher in CT positive group than in CT negative group (14 vs. 10 %, p < 0.05), but there was no significant difference of quantitative values (p = 0.10). Of 42 regions in 27 patients who had serial PET/CT scans that were initially PET-positive, 35 regions (83 %) turned negative on a later PET-scan. CONCLUSIONS: Focal uptake around the LSPs was commonly seen in the mid-lumbar vertebrae, independent of age, and was not always correlated with morphological changes. This uptake should not be assumed to represent osseous metastasis.