RÉSUMÉ
Neuroendocrine tumors have a propensity to metastasize, but rarely to the orbits. A 69-year-old woman with history of neuroendocrine tumor of pancreatic primary underwent routine follow-up In-pentetreotide (OctreoScan) imaging, with 24-hour whole-body planar images showing subtle right periorbital tracer uptake that localized to extraocular muscles on subsequent SPECT/CT. Orbital MRI further defined the location of these highly suspicious orbital metastases, which were treated with external radiation, with follow-up MRI showing decreased size of the orbital metastases. Early identification and treatment of orbital metastases is critical to help preserve vision and quality of life.
Sujet(s)
Tumeurs radio-induites/secondaire , Tumeurs neuroendocrines/secondaire , Tumeurs de l'orbite/secondaire , Radiopharmaceutiques/effets indésirables , Tomographie par émission monophotonique couplée à la tomodensitométrie/effets indésirables , Somatostatine/analogues et dérivés , Sujet âgé , Femelle , Humains , Imagerie par résonance magnétique , Tumeurs radio-induites/étiologie , Tumeurs neuroendocrines/étiologie , Tumeurs de l'orbite/étiologie , Tumeurs du pancréas/imagerie diagnostique , Tumeurs du pancréas/anatomopathologie , Somatostatine/effets indésirablesRÉSUMÉ
A 7-month-old boy with malignant rhabdoid tumor of the right lateral neck, status post resection and chemotherapy, underwent FDG PET/CT for restaging. The images showed diffuse increased activity in the spleen and in the bone marrow of the appendicular bones and the spine, which is related to hematopoietin administered after chemotherapy. The images also revealed intense activity in the region of sphenoid bone, which is not a common region to have elevated FDG activity. The subsequent MRI scan showed that this activity was due to not-yet-converted red marrow in the sphenoid bone in this pediatric patient.
Sujet(s)
Fluorodésoxyglucose F18 , Os sphénoïde/imagerie diagnostique , Humains , Nourrisson , Imagerie par résonance magnétique , Mâle , Tomographie par émission de positons couplée à la tomodensitométrie , Tumeur rhabdoïde/complications , Tumeur rhabdoïde/imagerie diagnostique , Tumeur rhabdoïde/anatomopathologie , Tumeurs du crâne/complications , Tumeurs du crâne/imagerie diagnostique , Tumeurs du crâne/anatomopathologie , Os sphénoïde/anatomopathologieRÉSUMÉ
Wallerian degeneration (WD) is defined as progressive anterograde disintegration of axons and accompanying demyelination after an injury to the proximal axon or cell body. Since the 1980s and 1990s, conventional magnetic resonance imaging (MRI) sequences have been shown to be sensitive to changes of WD in the subacute to chronic phases. More recently, advanced MRI techniques, such as diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI), have demonstrated some of earliest changes attributed to acute WD, typically on the order of days. In addition, there is increasing evidence on the value of advanced MRI techniques in providing important prognostic information related to WD. This article reviews the utility of conventional and advanced MRI techniques for assessing WD, by focusing not only on the corticospinal tract but also other neural tracts less commonly thought of, including corticopontocerebellar tract, dentate-rubro-olivary pathway, posterior column of the spinal cord, corpus callosum, limbic circuit, and optic pathway. The basic anatomy of these neural pathways will be discussed, followed by a comprehensive review of existing literature supported by instructive clinical examples. The goal of this review is for readers to become more familiar with both conventional and advanced MRI findings of WD involving important neural pathways, as well as to illustrate increasing utility of advanced MRI techniques in providing important prognostic information for various pathologies.