Fludeoxyglucose F 18 Positron Emission Tomography and Magnetic Resonance Perfusion Imaging in Patients With Neurofibromatosis 1 and Plexiform Neurofibroma

DISEASE CHARACTERISTICS: * Stratum 1: * Diagnosis of neurofibromatosis 1 (NF1) and plexiform neurofibromas * At high risk for progression, as defined by any of the following: * Anatomic location such that progression carries a high risk of impairment of function, pain, or disfigurement (e.g., neck/mediastinum, paraspinal nerve roots, orbit, and face) * Tumors that the patient, family, or caregiver believes have increased in size within the past year, but appear stable by standard clinical or radiographic measures * No plexiform neurofibromas that are small, cause no pain or functional impairment, or are not likely to cause pain or functional impairment over the succeeding 12 months * Stratum 2: * Diagnosis of NF1 and progressive plexiform neurofibromas * Neurofibroma progression documented by increase in lesion size on MRI * Currently being enrolled on a clinical therapeutic trial at Children's Hospital of Philadelphia PATIENT CHARACTERISTICS: Age * 25 and under Performance status * Not specified Life expectancy * Not specified Hematopoietic * Not specified Hepatic * Not specified Renal * Not specified Other * Not pregnant or nursing * Negative pregnancy test PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * Stratum 1: * No prior or concurrent chemotherapy * No concurrent enrollment on a chemotherapy clinical trial * Stratum 2: * At least 4 weeks since prior chemotherapy Endocrine therapy * Not specified Radiotherapy * At least 6 weeks since prior radiotherapy (stratum 2) Surgery * Prior surgery for progressive plexiform neurofibroma allowed if incompletely resected and measurable disease remains (stratum 2)