Article
F-18-FET-PET to image brain metastases
Search Medline for
Authors
Published: | June 4, 2012 |
---|
Outline
Text
Objective: FET-PET has been proposed to provide diagnostic information on brain metastases. Especially, the differentiation of postoperative or postradiation tissue changes from recurrent tumor during follow-up is of importance and FET-PET might be useful for this purpose. However, standardized uptake values (SUV) for brain metastases are unclear, so far.
Methods: Pts underwent FET-PET and MRI (Flair, T2*, DTI, T1 ± Gd-DTPA) before surgery for brain metastasis. Imaging data were fused (iPlan cranial 3.0). Uptake of FET was quantified by SUV. Imaging contrast was assessed by calculating lesion-to-gray matter ratios. GTV of tumors were assessed by semi-automatic segmentation (iPlan cranial 3.0).
Results: 30 patients were enrolled (origin of neoplasm: 8 breast; 7 NSCLC, 1 SCLC; 6 upper/lower GI, 3 renal, 2 lymphoma, 2 urinary bladder, 1 CUP). 13 pts had received brain radiation prior to surgical resection, 2 pts underwent treatment for recurrent, previously resected and irradiated brain metastases. In 28 pts histopathology revealed vital tumor tissue, in 2 pts necrotic/non vital tissue. All pts with a positive histopathology for vital tumor tissue displayed a SUV in FET-PET above 1.6. Pts with tumor negative histopathology displayed a SUV max below 1.6. Ratio of PET tumor volume (SUV > 1.6) to GTV (MRI + Gd) was 1.43 (SD ± 2.048). FET-PET delineated tumor tissue outside of MRI changes.
Conclusions: In this preliminary study FET-PET provided diagnostic information on newly diagnosed and recurrent (resected and/or previously irradiated) brain metastases. Applying an SUV ratio threshold of 1.6 FET-PET was positive in all pts with positive histopathology for vital tumor tissue and negative in pts harboring no vital tumor tissue. Therefore semiquantitative FET-PET could be helpful for differentiation of tumor progression from treatment associated tissue changes i.e pseudoprogression.