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Neuroradiology Case of the Week

Case 377

January 2009

Hisao Nakamura, MD and Per-Lennart Westesson MD, PhD, DDS

Clinical Presentation: Patient is a 46-year-old female with developing brain weakness of two months history.

Imaging Findings: Atypical perfusion imaging finding for metastatic tumor.

Diagnosis: Metastatic mucinous adenocarcinoma

Discussion: Before this examination was performed, our patient underwent a biopsy which demonstrated adenocarcinoma consistent with gastric cancer. She completed whole brain radiation therapy at another hospital. The purpose for coming to our hospital was to have consolidative stereotactic radiosurgery and this examination was performed for its planning.
     Solitary metastatic tumor is known to show high rCBV, so it cannot be differentiated from high grade glioma. However, the present case showed low rCBV. We suspected it was probably due to the effect of the recent radiation therapy, but it has no supporting evidence. There is a report concerning the differentiation of non-neoplastic tissue and recurrent tumor on the basis of rCBV [1]. If the normalized rCBV (the ratio of the mass and the contralateral normal side) is higher than 2.6 then tumor recurrence is suspected, while less than 0.6 then non-neoplastic tissue is suspected.

References:

1. Sugahara T, Korogi Y, Tomiguchi S, et al. Posttherapeutic intraaxial brain tumor: the value of perfusion-sensitive contrast-enhanced MR imaging for differentiating tumor recurrence from nonneoplastic contrast-enhancing tissue. AJNR Am J Neuroradiol. 2000 May;21(5):901-9. [PubMed]