Diagnostic and prognostic value of 18F-DOPA PET and 1H-MR spectroscopy in pediatric supratentorial infiltrative gliomas: a comparative study

Abstract

Background: (1)H-MR spectroscopy (MRS) and (18)F-dihydroxyphenylalanine (DOPA) PET are noninvasive imaging techniques able to assess metabolic features of brain tumors. The aim of this study was to compare diagnostic and prognostic information gathered by (18)F-DOPA PET and (1)H-MRS in children with supratentorial infiltrative gliomas or nonneoplastic brain lesions suspected to be gliomas.

Methods: We retrospectively analyzed 27 pediatric patients with supratentorial infiltrative brain lesions on conventional MRI (21 gliomas and 6 nonneoplastic lesions) who underwent (18)F-DOPA PET and (1)H-MRS within 2 weeks of each other. (1)H-MRS data (choline/N-acetylaspartate, choline-to-creatine ratios, and presence of lactate) and (18)F-DOPA uptake parameters (lesion-to-normal tissue and lesion-to-striatum ratios) were compared and correlated with histology, WHO tumor grade, and patient outcome.

Results: (1)H-MRS and (18)F-DOPA PET data were positively correlated. Sensitivity, specificity, and accuracy in distinguishing gliomas from nonneoplastic lesions were 95%, 83%, and 93% for (1)H-MRS and 76%, 83%, and 78% for (18)F-DOPA PET, respectively. No statistically significant differences were found between the 2 techniques (P > .05). Significant differences regarding (18)F-DOPA uptake and (1)H-MRS ratios were found between low-grade and high-grade gliomas (P≤.001 and P≤.04, respectively). On multivariate analysis, (18)F-DOPA uptake independently correlated with progression-free survival (P≤.05) and overall survival (P = .04), whereas (1)H-MRS did not show significant association with outcome.

Conclusions: (1)H-MRS and (18)F-DOPA PET provide useful complementary information for evaluating the metabolism of pediatric brain lesions. (1)H-MRS represents the method of first choice for differentiating brain gliomas from nonneoplastic lesions.(18)F-DOPA uptake better discriminates low-grade from high-grade gliomas and is an independent predictor of outcome.

Keywords: DOPA; PET; brain tumor; magnetic resonance spectroscopy; pediatric.

© The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Fig. 1.

Linear regression analysis of 18F-DOPA uptake and 1H-MRS ratios. All parameters are positively correlated. The strongest correlation is demonstrated between Cho/NAA and L/N Spect ratios (A).

Fig. 2.

Box plots representing 18F-DOPA uptake (A–D) and 1H-MRS ratios (E, F) for low-grade and high-grade gliomas.

Fig. 3.

MRI, 1H-MRS and 18F-DOPA PET images in nonneoplastic and neoplastic lesions. A–D. Meningioangiomatosis (case 27): axial FLAIR image reveals a lesion in the right frontal lobe (A). Single voxel 1H-MRS (B) shows normal Cho/Cr and Cho/NAA ratios. 18F-DOPA PET (C) and fused PET/MRI (D) images demonstrate absence of tracer uptake in the lesion. (E–H) Diffuse astrocytoma. WHO grade II (case 8) axial FLAIR image demonstrates a right parietal lesion extending across the splenium of the corpus callosum (E). Single voxel 1H-MRS (F) shows increased Cho/NAA ratio (1,30). 18F-DOPA PET (G) and fused PET/MRI (H) images show no evidence of increased uptake in the lesion. Following biopsy the patient was managed with a “watch and wait” approach, and the lesion remained stable during follow-up (26 months). I–L. Glioblastoma multiforme. WHO grade IV (case 21) axial FLAIR image reveals a lesion involving the right diencephalic-mesencephalic junction and basal ganglia (I). Single voxel 1H-MRS (J) demonstrates increased Cho/NAA (3:90) and Cho/Cr (9:80) ratios. 18F-DOPA PET (K), and fused PET/MRI (L) images show increased tracer uptake in the lesion (L/N: 2.23, L/S: 1.58). Following biopsy, the patient was treated with chemotherapy and radiotherapy; the OS was 8 months. Note: the box on the FLAIR images indicates the region of interest from which the spectra were acquired.

Fig. 4.

Kaplan-Meier overall survival (OS) curves for all of the main factors analyzed in our study: 18F-DOPA PET results. (A–D), low-grade versus high-grade gliomas (E), tumor dimension (F) and 1H-MRS (G and H) results. 18F-DOPA PET and 1H-MRS parameters were categorized considering tertiles of each distribution.