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AJR Am J Roentgenol. 2018 Dec;211(6):1342-1347. doi: 10.2214/AJR.18.19988. Epub 2018 Oct 17.

Voxel-Wise Analysis of Fluoroethyltyrosine PET and MRI in the Assessment of Recurrent Glioblastoma During Antiangiogenic Therapy.

Author information

1
1 Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115.
2
2 Center for Neurooncology, Dana-Farber Cancer Institute, Boston, MA.
3
3 John Wayne Cancer Institute and Pacific Neuroscience Institute at Providence Saint John's Health Center, Santa Monica, CA.

Abstract

OBJECTIVE:

In MRI of patients with recurrent glioblastoma, bevacizumab-induced normalization of tumor vascularity can be difficult to differentiate from antitumor effects. The aim of this study was to assess the utility of 18F-fluoroethyl-L-tyrosine (FET) PET in the evaluation of recurrent glioblastoma treated with bevacizumab.

SUBJECTS AND METHODS:

MRI and FET PET were performed before and after administration of two doses of bevacizumab to 11 patients with recurrent glioblastoma. The ratio between normalized FET uptake at follow-up and baseline of the entire (volume of T2 FLAIR abnormality) and enhancing tumor were assessed for prediction of progression-free survival (PFS) and overall survival (OS). Voxel-wise Spearman correlation between normalized FET uptake and contrast-enhanced T1 signal intensity was assessed and tested as a predictor of PFS and OS.

RESULTS:

Mean Spearman correlation between FET uptake and contrast-enhanced T1 signal intensity before therapy was 0.65 and after therapy was 0.61 (p = 0.256). The median PFS after initiation of bevacizumab therapy was 111 days, and the OS was 223 days. A post-treatment to pretreatment PET uptake ratio (mean and 90th percentile) greater than 0.7 for both entire and enhancing tumor was associated with lower PFS and OS (p < 0.001-0.049). The increase in correlation between PET uptake and contrast-enhanced T1 intensity after treatment was associated with lower PFS (p < 0.001) and OS (p = 0.049).

CONCLUSION:

There is only a moderate correlation between FET PET uptake and contrast-enhanced T1 signal intensity. High posttreatment-to-pretreatment FET PET uptake ratio and increase in correlation between PET uptake and contrast-enhanced T1 signal intensity after bevacizumab treatment are associated with poor PFS and OS.

KEYWORDS:

FET; MRI; PET; bevacizumab; fluoroethyl tyrosine; glioblastoma

PMID:
30332289
DOI:
10.2214/AJR.18.19988
[Indexed for MEDLINE]

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