Imaging the Postoperative Brain
Stereotactic biopsy is an image-guided procedure that is commonly performed to obtain tissue samples of intracranial lesions. Hemorrhage is one of the most common findings after stereotactic brain biopsy, occurring in up to 9 % of cases.
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Imaging the Postoperative Brain Daniel Thomas Ginat and Pamela W. Schaefer
5.1
Brain Tumors
5.1.1
Stereotactic Brain Biopsy
5.1.1.1 Discussion Stereotactic biopsy is an image-guided procedure that is commonly performed to obtain tissue samples of intracranial lesions. Hemorrhage is one of the most common findings after stereotactic brain biopsy, occurring in up to 9 % of cases. Hemorrhage along the biopsy track has a characteristic linear configuration (Fig. 5.1). Mild enhancement along the biopsy track can also be seen. Small needle track hemorrhages are usually of little clinical significance and will resolve spontaneously. The changes along the track usually remain visible for at least a few weeks after biopsy and can serve as an indicator of whether the lesion was appropriately sampled. Although off-target biopsy can yield tumor cells if the lesion is an infiltrative tumor, the grade may be underestimated. Ideally, biopsy or the enhancing portion of the tumor with the highest cerebral blood volume D.T. Ginat, M.D., MS () Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA e-mail: [email protected] P.W. Schaefer, M.D. Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA Department of Neuroradiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA
(CBV) on perfusion-weighted MRI should be performed. Another uncommon, but notable complication of stereotactic biopsy, is tumor seeding (Fig. 5.2).
5.1.2
Resection Cavities, Tracks, and Surrounding Changes
5.1.2.1 Discussion The space that remains after a tumor is surgically removed is known as the resection cavity. The resection cavity is often lined or packed with hemostatic agents (refer to Chap. 4) and contains variable amounts of CSF and blood products, especially during the early postoperative period (Fig. 5.3). Thin linear enhancement along the resection cavity margins is a common finding following tumor resection or any cephalotomy (Fig. 5.4) and is generally due to the formation of granulation tissue. The enhancement appears within the first postoperative week (usually after 2 or 3 days), intensifies over the ensuing weeks, and resolves over 3–5 months. The enhancement is typically linear and smooth but can become more nodular by 1 week following surgery. Since residual enhancing tumor can be obscured or confounded by granulation tissue, baseline imaging is recommended within 48 h of surgery, before granulation tissue forms. Serial imaging can also help to differentiate granulation tissue from residual tumor in that tumor increases in size over time, while granulation tissue should remain stable and eventually resolves. The uncomplicated resection
D.T. Ginat, P.-L.A. Westesson, Atlas of Postsurgical Neuroradiology, DOI 10.1007/978-3-642-15828-5_5, © Springer-Verlag Berlin Heidelberg 2012
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Imaging the Postoperative Brain
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Fig. 5.1 Biopsy track hemorrhage. Axial CT image (a) demonstrates linear high density along the biopsy track in the region of the right lentifo
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