RESUMEN
^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
RESUMEN
AIM: Recently, a high-resolution dedicated PET system for hanging breast imaging (MAMMI PET) has been developed to improve primary tumor detection and characterization. The aim of this pilot study was to assess its feasibility for tumor detection and FDG uptake measurements in patients with stage II and III breast cancer. METHODS: Thirty-two patients with invasive breast cancer (26 ductal, 4 lobular, 2 other), prior to and/or during neoadjuvant chemotherapy, underwent both conventional PET/CT and MAMMI PET in prone position with hanging breasts. Conventional PET/CT and MAMMI PET were performed 60±10 min and 110±10 min after injection of 180-240 MBq of FDG, respectively. Primary tumor detection was assessed and FDG uptake, expressed as maximum standardized uptake value (SUVmax), was calculated. RESULTS: Both MAMMI PET and conventional PET/CT visualized the primary tumor in 31 patients (97%). The mean distance from the tumor to the pectoral muscle was 26.4mm (smallest distance 3.3mm). Agreement in FDG uptake between PET/CT and MAMMI PET was high (r=0.86, 95% CI 0.69-0.94). However, SUVmax as assessed with MAMMI PET was consistently higher than with PET/CT in all patients with an average ratio of 2.7. CONCLUSION: The dedicated high-resolution breast PET with hanging breast technique is able to visualize approximately all breast tumors in stage II and III breast cancer patients, including tumors in the vicinity of the thoracic wall. This may enable its sequential use in the assessment of response in breast cancer patients receiving neoadjuvant systemic therapy, although SUVmax values are not directly comparable to standard PET/CT.