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Purpose: Respiratory gating is an established approach to overcoming respiration-induced image artefacts in PET. Of special interest in this respect are raw PET data-driven gating methods which do not require additional hardware to acquire respiratory signals during the scan. However, these methods rely heavily on the quality of the acquired PET data (statistical properties, data contrast, etc.). We therefore combined external radioactive markers with data-driven respiratory gating in PET/CT. The feasibility and accuracy of this approach was studied for [(18)F]FDG PET/CT imaging in patients with malignant liver and lung lesions., Methods: PET data from 30 patients with abdominal or thoracic [(18)F]FDG-positive lesions (primary tumours or metastases) were included in this prospective study. The patients underwent a 10-min list-mode PET scan with a single bed position following a standard clinical whole-body [(18)F]FDG PET/CT scan. During this scan, one to three radioactive point sources (either (22)Na or (18)F, 50-100 kBq) in a dedicated holder were attached the patient's abdomen. The list mode data acquired were retrospectively analysed for respiratory signals using established data-driven gating approaches and additionally by tracking the motion of the point sources in sinogram space. Gated reconstructions were examined qualitatively, in terms of the amount of respiratory displacement and in respect of changes in local image intensity in the gated images., Results: The presence of the external markers did not affect whole-body PET/CT image quality. Tracking of the markers led to characteristic respiratory curves in all patients. Applying these curves for gated reconstructions resulted in images in which motion was well resolved. Quantitatively, the performance of the external marker-based approach was similar to that of the best intrinsic data-driven methods. Overall, the gain in measured tumour uptake from the nongated to the gated images indicating successful removal of respiratory motion was correlated with the magnitude of the respiratory displacement of the respective tumour lesion, but not with lesion size., Conclusion: Respiratory information can be assessed from list-mode PET/CT through PET data-derived tracking of external radioactive markers. This information can be successfully applied to respiratory gating to reduce motion-related image blurring. In contrast to other previously described PET data-driven approaches, the external marker approach is independent of tumour uptake and thereby applicable even in patients with poor uptake and small tumours.

Purpose: To evaluate the efficacy of radiation therapy (RT) for symptomatic vertebral hemangioma (SVH)., Material and Methods: Based on the Registry for Rare Benign Disorders (RRBD) of the German Cooperative Group on Radiation Therapy for Benign Diseases (GCG-BD), the clinical information, treatment plans and outcome data from seven cooperating German RT institutions were analyzed retrospectively., Results: Over a period of 39 years (1969-2008), a total of 84 patients with 96 symptomatic lesions underwent RT. The predominant indication was pain in 97.6%, and, in addition, 28.6% of patients had neurological deficits. The median total dose was 34 Gy (4.5-45 Gy), and the median single dose 2.0 Gy (0.5-3.0 Gy). After a median follow-up of 68 months (6-422 months), complete symptom relief (CR) occurred in 61.9% of patients, 28.6% had partial relief, and 9.5% had no relief (NR). The overall response rate (CR + PR) was 90.5%. In 26.2% of patients, radiologic signs of remineralization were noted. After a median follow-up of 70 months (8-124 months), symptom progression occurred in eight patients (9.5%). Therefore, the long-term rate of local control was 80.9%. Multivariate statistical analysis revealed a significantly higher rate of symptom relief and local control for total doses > or = 34 Gy. Side effects > RTOG/EORTC grade 2 were not observed., Conclusion: RT is a safe and effective for treatment of SVH. Total doses of at least 34 Gy are recommended to achieve optimal treatment response.