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This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Wardak, M. Articles by Schiepers, C. PubMed Articles by Wardak, M. Articles by Schiepers, C.

Monitoring brain tumor therapy with 18F-FLT

¹ David Geffen School of Medicine at UCLA, Los Angeles, California

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Objectives: FLT is a predictor of survival in recurrent glioma therapy (JCO 2007;25:4714-21). We investigated changes in FLT kinetics during treatment.

Methods: High-grade brain tumors were investigated in thirteen patients (5 men, 8 women), 26-70 yr. Each had 3 dynamic PET studies, at baseline (study 1), 2 weeks after start of treatment (study 2) and 6 weeks (study 3). 1.5 MBq/kg 18F-FLT was administered, dynamic images acquired for 1 hr and iteratively reconstructed. PET studies were coregistered and resampled with SPM to contrast enhanced baseline T1-weighted MR with isotropic voxels. Factor analysis generated factor images, from which blood curve and tumor uptake curves were derived. A 75% isocontour of the tumor maximum on the tumor factor image was used to define ROIs for each study. A cubic ROI of 1.8 mL was also defined on the baseline scan and the 3 studies processed with the ROI in the same position. A 3-compartment, 2-tissue model was applied with metabolite and partial volume corrections to estimate the rate constants.

Results: No significant differences were found between parameters derived from the original vs the MR-aligned PET images (p>0.1; r >0.9). A linear relationship was found between transport rate k1 and influx rate K, and between K and SUV. Significant differences (p<0.05) were found for K and SUV between all 3 studies, and for k1 in study 1 vs 2. From study 1 to 2, K decreased by 26%, SUV by 30% and k1 by 36%. During 2 weeks follow up, the largest change in k1, K, and SUV was seen in patients with a favorable response. Parameter changes are correlated with patient survival.

Conclusions: Compartmental analysis of FLT during treatment shows a linear relation between K and SUV, of which the sharpest decline is between baseline and 2 weeks follow up. It appears adequate to monitor therapy response with SUV in clinical practice.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Wardak, M. Articles by Schiepers, C. PubMed Articles by Wardak, M. Articles by Schiepers, C.