We evaluated the diagnostic accuracy of PET with L-methyl-11 Cmethionine ( 11 C-MET) for the differentiation of recurrent brain tumors from radiation necrosis. Methods: Seventy-seven patients who had been previously treated with radiotherapy after primary treatment for metastatic brain tumor (n 5 51) or glioma (n 5 26) were studied to clarify the diagnostic performance of 11 C-MET PET in differentiating between recurrent brain tumors and radiation necrosis. A total of 88 PET scans with 11 C-MET were obtained; sometimes more than one scan was obtained when there was an indication of recurrent brain tumor or radiation necrosis. A definitive diagnosis was made on the basis of pathologic examination for recurrent brain tumors and on the basis of pathologic examination or clinical course for radiation necrosis. Several indices characterizing the lesions were determined; these included mean and maximum standardized uptake values (SUV mean and SUV max , respectively) and the ratios of lesion uptake to contralateral normal frontal-lobe gray matter uptake corresponding to the SUV mean and the SUV max (L/N mean and L/N max , respectively). Receiver-operating-characteristic (ROC) curve analysis was used to determine the optimal index of 11 C-MET PET and cutoff values for the differential diagnosis of tumor recurrence and radiation necrosis. Results: The values of each index of 11 C-MET PET tended to be higher for tumor recurrence than for radiation necrosis. There were significant differences between tumor recurrence and radiation necrosis in all of the indices except for the L/N max for glioma. ROC analysis indicated that the L/N mean was the most informative index for differentiating between tumor recurrence and radiation necrosis. An L/N mean of greater than 1.41 provided the best sensitivity and specificity for metastatic brain tumor (79% and 75%, respectively), and an L/N mean of greater than 1.58 provided the best sensitivity and specificity for glioma (75% and 75%, respectively). Conclusion: 11 C-MET PET can provide quantitative values to aid in the differentiation of tumor recurrence from radiation necrosis, although these values do not appear to be absolute indicators. Quantitative analysis of 11 C-MET PET data may be helpful in managing irradiated brain tumors. Pri mary treatment of brain tumors usually consists of a combination of surgery, radiotherapy, and chemotherapy. Postradiation reactions in the central nervous system can occur after conventional radiotherapy and stereotactic radiosurgery (SRS) (1). Radiation necrosis after the aggressive use of irradiation for malignant brain tumors appears to be more common than previously estimated (2). Differentiating between recurrent brain tumors and radiation necrosis, however, is often difficult with conventional diagnostic imaging techniques, such as MRI (3). This is an unsolved issue in managing irradiated brain tumors.Recently, several imaging modalities, such as MR spectroscopy (4-6), SPECT with 201 Tl-chloride ( 201 Tl) (7), and PET with various radiotracers (...

The use of MET-PET scanning is a sensitive and accurate technique for differentiating between metastatic brain tumor recurrence and radiation necrosis following stereotactic radiosurgery. This study reveals important information for creating strategies to treat postradiation reactions.

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There were no significant differences between recurrent malignant glioma and radiation necrosis following SRS in Met-PET. However, this study shows Met-PET has a sensitivity and accuracy for differentiating between recurrent glioma and necrosis, and presents important information for developing treatment strategies against post radiation reactions.

The microsurgical anatomy of the jugular foramen was studied in 10 fixed cadavers, each cadaver consisting of the whole head and neck. Five of the cadavers were injected with latex. The jugular foraminal region was exposed using the infratemporal fossa type A approach of Fisch and Pillsbury in five cadavers (10 sides) and the combined cervical dissection-mastoidectomy-suboccipital craniectomy approach in five cadavers (10 sides). The right foramen was larger than the left in seven cases (70%), equal in two cases (20%), and smaller in one case (10%). The dura covering the intracranial portal of the foramen had two perforations, a smaller anteromedial perforation through which passed the ninth cranial nerve (CN IX), and a larger posterolateral perforation, through which passed the 10th and 11th cranial nerves (CNs X and XI) and the distal sigmoid sinus. The perforations were separated by a fibrous septum in 16 specimens (80%). After exiting the posterior fossa, CNs IX, X, and XI all lay anteromedial to the superior jugular bulb (SJB) within the jugular foramen. The inferior petrosal sinus (IPS) entered the foramen between CNs IX and X in most cases; however, in 10% of our cases it entered the foramen between CNs X and XI, and in 10% it entered the foramen caudal to CN XI. The IPS terminated in the SJB in 90% of our cases; in 40%, the IPS termination consisted of multiple channels draining into both the SJB and internal jugular vein. This study shows that the arrangement of the neurovascular structures within the jugular foramen does not conform to the hitherto widely accepted notion of discrete compartmentalization into an anteromedial pars nervosa containing CN IX and the IPS and a posterolateral pars venosa containing the SJB, CNs X and XI, and the posterior meningeal artery.