Therapeutic impact of 2-[fluorine-18]fluoro-2-deoxy-D-glucose positron emission tomography in the pre- and postoperative staging of patients with clinically intermediate or high-risk breast cancer

Background: Positron emission tomography with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG-PET) is an accurate imaging modality for the staging of breast cancer. The aim of this study was to determine the potential therapeutic impact of pre- and postoperative FDG-PET in patients with clinically intermediate or high-risk breast cancer. Patients and methods: One hundred and fourteen patients with newly diagnosed breast cancer were examined before (73) or after (41) surgery. Patient data were translated into three scoring sheets corresponding to information available before positron emission tomography (PET), after PET and after further diagnostic tests. Three medical oncologists independently reviewed the retrospectively acquired patient data and prospectively made decisions on the theoretically planed treatment for each time point, according to the recommendations of St Gallen Consensus Guidelines 2005. Results: FDG-PET changed the planed treatment in 32% of 114 patients. In 20% of cases, therapeutic intention (curative versus palliative) was modified. Radiation treatment planning was changed in 27%, surgical planning in 9%, chemotherapy in 11% and intended therapy with bisphosphonates in 13% of all patients. Conclusion: Based on current treatment guidelines, FDG-PET, as a staging procedure in patients with newly diagnosed clinically intermediate or high-risk breast cancer examined pre- and postoperatively, may have a substantial therapeutic impact on treatment plannin

PET-CT-guided interventions in the management of FDG-positive lesions in patients suffering from solid malignancies: initial experiences

Positron emission tomography-computed tomography (PET-CT) has gained widespread acceptance as a staging investigation in the diagnostic workup of malignant tumours and may be used to visualize metabolic changes before the evolution of morphological changes. To make histology of PET findings without distinctive structural changes available for treatment decisions, we developed a protocol for multimodal image-guided interventions using an integrated PET-CT machine. We report our first experience in 12 patients admitted for staging and restaging of breast cancer, non-small cell lung cancer, cervical cancer, soft tissue sarcoma, and osteosarcoma. Patients were repositioned according to the findings in PET-CT and intervention was planned based on a subsequent single-bed PET-CT acquisition of the region concerned. The needle was introduced under CT guidance in a step-by-step technique and correct needle position in the centre of the FDG avid lesion was assured by repetition of a single-bed PET-CT acquisition before sampling. The metabolically active part of lesions was accurately targeted in all patients and representative samples were obtained in 92%. No major adverse effects occurred. We conclude that PET-CT guidance for interventions is feasible and may be promising to optimize the diagnostic yield of CT-guided interventions and to make metabolically active lesions without morphological correlate accessible to percutaneous interventions

Technical Note: Transconvolution based equalization of positron energy effects for the use of 68 Ge/68 Ga phantoms in determining 18 F PET recovery.

PURPOSE Avoiding measurement variability from 18 F phantom preparation by using 68 Ge/68 Ga phantoms for the determination of 18 F recovery curves (RC) in clinical quality assurance measurements and for PET/CT site qualification in multicentre clinical trials. METHODS RCs were obtained from PET/CT measurements of seven differently sized phantom spheres filled either with 18 F or with 68 Ga. RCs for the respective other isotope were then determined by two different methods: In the first method, images were convolved with positron range transconvolution functions derived from positron annihilation distributions found in literature. This method generated recasted images matching images using the respective other isotope. In the second method, the PET/CT system's isotope independent (intrinsic) point spread function was determined from said phantom measurements and convolved with numerical representations simulating hot spheres filled with the respective other isotope. These simulations included the isotope specific positron annihilation distributions. Recovered activity concentrations were compared between recasted images, simulated images, and the originally acquired images. RESULTS 18 F and 68 Ga recovery was successfully determined from image acquisitions of the respective opposite isotope as well as from the simulations. 68 Ga RCs derived from 18 F data had a normalized root-mean-square deviation (NRMSD) from real 68 Ga measurements of 0.019% when using the first method and of 0.008% when using the second method. 18 F RCs derived from 68 Ga data had a NRMSD from real 18 F measurements of 0.036% when using the first method and of 0.038% when using the second method. CONCLUSIONS Applying the principles of transconvolution, 18 F RCs can be recalculated from 68 Ga phantom measurements with excellent accuracy. The maximal additionally introduced error was below 0.4% of the error currently accepted for RCs in the site qualification of multicentre clinical trials by the EARL program of the European Association of Nuclear Medicine (EANM). Therefore, our methods legitimately allow for the use of long-lived solid state 68 Ge/68 Ga phantoms instead of manually prepared 18 F phantoms to characterize comparability of 18 F measurements across different imaging sites or of longitudinal 18 F measurements at a single PET/CT system

PET/CT-guided biopsies of metabolically active bone lesions: applications and clinical impact

In a minority of cases a definite diagnosis and stage grouping in cancer patients is not possible based on the imaging information of PET/CT. We report our experience with percutaneous PET/CT-guided bone biopsies to histologically verify the aetiology of hypermetabolic bone lesions