Radiotherapy treatment planning and long-term follow-up with [(11)C]methionine PET in patients with low-grade astrocytoma.

PURPOSE: To evaluate the feasibility of [(11)C]-methionine positron emission tomography (MET PET) in radiotherapy (RT) treatment planning and long-term follow-up in patients with low-grade glioma. PATIENTS: Thirteen patients with low-grade astrocytoma and 1 with anaplastic astrocytoma underwent sequential MET PET and magnetic resonance imaging (MRI) before and 3, 6, 12, and 21-39 months after RT, respectively. Ten patients were studied after initial debulking surgery or biopsy and 4 in the recurrence phase. METHODS: A total of 58 PET scans were performed. After transmission scanning, a median dose of 425 MBq of MET was injected intravenously and emission data was acquired 20 min after injection for 20 min. The uptake of MET in tumor area was measured as standardized uptake value (SUV) and tumor-to-contralateral brain SUV ratios were generated to assess irradiation effects on tumor metabolism. Functional imaging with PET was compared with concurrent MRI in designing the RT planning volumes and in assessment of response to RT during a median follow-up time of 33 months. RESULTS: In 12 patients (86%), tumor area was clearly discernible in the baseline PET study. In the remaining 2 patients with a suspected residual tumor in MRI, PET showed only a diffuse uptake of MET interpreted as negative in the original tumor area. In the dose planning of RT, MET PET was helpful in outlining the gross tumor volume in 3 of 11 cases (27%), whereas PET findings either coincided with MRI (46%) or were less distinctive (27%) in other cases. In quantitative evaluation, patients with a low tumor SUV initially had significantly better prognosis than those with a high SUV. Tumor-to-contralateral brain uptake ratios of MET discriminated well patients remaining clinically stable from those who have since relapsed or died of disease. CONCLUSION: Quantitative MET PET has prognostic value at the time of initial treatment planning of low-grade glioma. Some patients may benefit of RT volume definition with MET PET, which seems to disclose residual tumor better than MRI in selected cases. Stable or decreasing uptake of MET in tumor area after RT during follow-up seems to be a favorable sign.

Adolescents' ideas of normative life span development and personal future goals.

We investigated how 57 adolescents (23 girls and 34 boys), aged 12 to 15 years, compared their idea of normative life span development to their personal future goals. A two-stage study (questionnaire and follow-up interview) included two open-ended "life paths", measures for self-evaluation and self-other comparisons. Overlap of content categories in the life paths supported the relationship between individual goals and normative expectations about life span development, especially when it comes to the life domains of education, occupation, family, property and retirement. The respondents showed an awareness of the accumulation of social problems, reporting that crises (e.g. alcoholism) and negative events (e.g. unemployment) are more likely to occur to the average adult than in their personal future. If adolescents rated their future as better than the future of others, they also regarded that future as different from the normative life span. Self-evaluation was indirectly related with self-other comparisons. Similarity between the normative life span and personal future correlated with higher probability of problem occurrence and possibility to avoid the problems.

[PET-findings in head-and neck cancers]. / PET-fynd vid huvud-och halscancer.

Head and neck cancer is very suitable for investigation with PET (positron emission tomography), usually owing to the locoregional spread at the time of diagnosis. Thus, the data collected enable any lesions present to be visualised. Evaluation of tumour metabolism with PET may simplify the diagnosis of metastases, and be of predictive value, enabling response to radiotherapy and cytostatic therapy to be predicted. It serves as a complement to CT (computed tomography) and MRI (magnetic resonance imaging) in the diagnosis of recurrence, and is thus useful in planning surgical intervention. Methods capable of distinguishing hypoxic or rapidly dividing cells can be useful in the choice of effective treatment methods such as hyperfractionated radiotherapy, drugs which enhance radiosensitivity, the degree of radical surgery, and the use of gene therapy.