Case Author(s): Charles Pringle, M.D., and Farrokh Dehdashti, M.D. , 06/03/96 . Rating: #D4, #Q4

Diagnosis: Recurrent(residual) left frontal astrocytoma.

Brief history:

History of brain tumor with recent syncopal episode


Axial images

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View second image(pt). Coronal P.E.T. images

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Full history/Diagnosis is available below

Diagnosis: Recurrent(residual) left frontal astrocytoma.

Full history:

31-year old man with history of grade II astrocytoma of the left frontal lobe, status post resection four years previously and also external beam radiation therapy. The patient had done well until recently when he experienced a syncopal episode at work.


10.8 mCi F-18 fluorodeoxyglucose i.v.


There is intense abnormal FDG accumulation in the left frontal lobe, which extends across the mid line in the region of the corpus callosum. This pattern does correspond to the abnormal signal on the MRI examination in the same region. The MRI also demonstrated an area of abnormal signal in the left parietal lobe with peripheral enhancement. No corresponding PET abnormality was noted. It has been shown that in brain tumors following therapy, FDG uptake into a contrast-enchancing lesion suggests the presence of viable tumor, while absent FDG uptake suggests necrosis. FDG PET is very useful in differentiating residual/recurrent tumor from post-therapeutic changes as post-therapy MRI is unable to differentiate tumor from benign changes due to therapy.


This study demonstrates the utility of PET imaging in the evaluation of sites of previous tumor within the brain which could represent recurrent or residual tumor vs postoperative changes.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Skull and Contents, Category:Neoplasm, Neoplastic-like condition)

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Case number: pt010

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