Neuroendocrine tumors: beyond the abdomen.

Several classification systems for neuroendocrine tumors (NETs) exist, which use variable terminology and criteria for grading and staging. This variability in terminology can cause confusion and difficulty in recognizing which tumors are, in fact, members of this heterogeneous group of malignancies. The largest group of NETs, the gastroenteropancreatic NETs, has been well described and characterized; however, there are less-recognized extra-abdominal NETs that can arise from nearly any organ in the body. In this article, the clinical features and imaging appearances of the extra-abdominal NETs will be reviewed, compared, and contrasted. This diverse group consists of paragangliomas, Merkel cell carcinomas, esthesioneuroblastomas, NETs of the lung, and medullary thyroid carcinomas. Recognition of these tumors as part of the larger group of NETs is important for understanding how best to approach imaging for their diagnosis, staging, and potential treatment. Familiarity with the computed tomographic and magnetic resonance imaging appearances and the role of radionuclide imaging of these heterogeneous groups aids in the correct diagnosis and in treatment planning.

Posterior reversible encephalopathy syndrome on computed tomography perfusion in a patient on "Triple H" therapy.

INTRODUCTION: This article reports a case of posterior reversible encephalopathy syndrome on compyted tomography (CT) perfusion in a patient on "Triple H" (hypertension, hypervolemia, and hemodilution) therapy following aneurysmal rupture repair. CASE REPORT: "Triple H" therapy is used in the postoperative course for treatment of vasospasm to prevent stroke and hemorrhage by maintaining cerebral perfusion pressure. DISCUSSION: A potential complication includes vasogenic edema from dysfunction of cerebral blood vessel autoregulation. CT perfusion can detect alterations in cerebral blood flow and volume caused by these hemodynamic changes.