What effective technique to differentiate radiation brain necrosis from a tumor progression in patients treated with radiation: A monocentric retrospective study combining the MRI TRAMs technique and the (18F)-dopa PET/CT.

PURPOSE: Brain necrosis after radiotherapy is a challenging diagnosis, since it has similar radiological appearance on standard MRI to tumor progression. Consequences on treatment decisions can be important. We compare recent imaging techniques in order to adopt a reliable diagnostic protocol in doubtful situations. PATIENTS AND METHOD: This is a retrospective study comparing the performance of three imaging techniques after radiotherapy of brain metastasis: Perfusion-MRI, TRAMs technique and F-dopa PET-CT. The evolution of the treated metastasis volume was also analyzed by contouring all patients MRIs. All included patients were suspected of relapse and had the three exams once the volume of treated metastasis increased. RESULTS: The majority of our patients were treated by stereotactic radiotherapy. Suspicion of relapse was on average around 17months after treatment. Four cases of radionecrosis were diagnosed and six cases of real tumor progression. Neurological symptoms were less present in radionecrosis cases. All of our radionecrosis cases had relative cerebral blood volume below 1. F-dopa PET-CT succeeded to set the good diagnosis in eight cases, although we found one false positive and one false negative exam. The TRAMs technique failed in one case of false negative exam. CONCLUSIONS: Perfusion-MRI showed high performance in the diagnosis of radionecrosis, especially when calculating relative cerebral blood volume rate. The TRAMs technique showed interesting results and deserves application in daily routine combined with the perfusion-MRI. F-dopa CT might induce false results because of different metabolic uptake according to tumor type, medication and brain blood barrier leak.

Postoperative radiotherapy after pneumonectomy: impact of modern treatment facilities.

PURPOSE: The present study was undertaken to see how modern treatment facilities, computed tomography (CT)-based treatment planning and linear accelerator, have modified the results of postoperative irradiation after a pneumonectomy for lung cancer. METHODS AND MATERIALS: Between 1970-1985, 103 patients were treated in our department after a pneumonectomy: 50 patients with a T1T2N0 tumor and 53 patients with a T3, N1 or N2 tumor. Three groups were considered: 27 patients had only surgical resection, 51 patients were irradiated postoperatively with a Co60 source, and 25 patients were treated using those modern facilities. RESULTS: The 5-year survival varies from 4% to 31% according to the tumor extent but also to the radiation technique. Patients treated with a Co60 source had a dismal 5-year survival rate (8%) whereas patients treated with the modern facilities had a 5-year survival rate of 30% similar to the 31% of the control surgical group including less advanced tumors. CONCLUSION: Linear accelerator and computed tomography-based treatment planning improved the accuracy of postoperative thoracic irradiation and allow to deliver high doses to the mediastinum even after a pneumonectomy.

Postoperative irradiation for thyroid cancer.

The place of external irradiation for thyroid cancers remains controversial. Between 1974 and 1989, 94 patients with a differentiated thyroid cancer were seen in our department for additional treatment (radioiodine with or without external radiation) after a surgical resection. 56 patients were treated with radioiodine alone and 38 patients had an additional course of external radiation. Survival was identical for the two groups but the local relapse rates were 21% and 3% respectively. So, in this retrospective study, the addition of external radiation appears to improve the local control especially in the case of an incomplete surgical resection or extracapsular tumor extension. This benefit was achieved without severe radiation-induced late effects.