Primary Neoplasms

36    Primary Neoplasms

Spinal neoplasias can be classified into lesions originating from the extradural, intradural extramedullary, and medullary spaces. Of the latter, astrocytomas are the most common in the cervical spine, frequently occurring in the thoracic spine as well. Astrocytomas classically span several vertebral segments in length and involve nearly the entire cross-section of the cord, the latter resulting in an expansile appearance on T1WI. Hyperintensity on T2WI reflects both the lesion and its surrounding edema. Enhancement is almost always present, to a degree, although some lesions and in particular more necrotic tumors may only enhance on delayed scans (30–60 minutes following contrast administration). Enhancement of the wall of cystic lesions aids in distinguishing them from otherwise similar appearing benign cystic lesions in the cord. Complex syrinxes too may mimic the appearance of an astrocytoma, although the walls of the latter are generally less distinct and CSF-pulsation artifacts absent. Contrast-enhanced MRI further aids in the distinction and should also be utilized in the initial workup of any syrinx without obvious cause (i.e., Chiari malformations).

Postoperatively, contrast administration is useful in differentiating nonenhancing postoperative changes from recurrent tumor, the latter almost invariably enhancing. In terms of differential diagnosis, an enhancing lesion of substantial craniocaudal extent could potentially represent cord ischemia or infarction, although this is very uncommon in the cervical spine. Unlike astrocytomas, ependymomas demonstrate a predilection for the lumbar spine; they are the most common tumor arising from the cauda equina and conus. Myxopapillary subtypes (see Chapter 51

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Aug 27, 2016 | Posted by in NUCLEAR MEDICINE | Comments Off on Primary Neoplasms
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