MR OF MALIGNANT NASOSINUSAL NEOPLASMS - FREQUENTLY ASKED QUESTIONS

This paper focuses on the role of MR imaging of malignant neoplasms th rough a particular layout that emphasizes: (a) the rationale for the a pplication of imaging; (b) the factors influencing the selection of se quences, planes and their proper arrangement; (c) the correlation betw een MR findings, imaging staging and clinical decision making. Since i n most cases surgery is the treatment of choice, the precise assessmen t of the local extent and spread of tumour plays a key role in plannin g the surgical approach and influences either the therapy and the prog nosis. However, the degree of spatial/anatomical detail required in tr eatment planning significantly differs between surgery and radiotherap y. Planning of the examination technique focuses on: (a) assembling se quences and planes in the shortest time possible; (b) the solution of specific problems: distinction between neoplasm and retained secretion s within nasosinusal cavities; staging of submucosal spread toward the anterior cranial fossa, the orbit, the pterygo-palatine and superior orbital fissures. Since the most effective barrier to spread of neopla sms beyond sinusal walls does not depend on the mineral content of bon e, but on the periosteum, assessment of the integrity of periorbita or dura mater is an essential information. Although MR cannot detect foc al erosions of the thin sinusal walls, it reliably demonstrates both r esidual barriers (periorbita and dura), even though the bone has been completely destroyed. However, the final decision concerning orbital e xenteration is made according to intraoperative staging. MR imaging ca n accurately precise the degree of anterior cranial fossa involvement. Furthermore, since either MR and CT accurately indicate the need to p erform an anterior craniofacial resection and adequately exclude neopl astic invasion requiring orbital exenteration, more comparative studie s are required to demonstrate that MR preoperative staging of nasosinu sal malignancies is cost-effective. (C) 1997 Elsevier Science Ireland Ltd.