Quantitative multi-modal MR imaging as a non-invasive prognostic tool for patients with recurrent low-grade glioma

Abstract

Low-grade gliomas can vary widely in disease course and therefore patient outcome. While current characterization relies on both histological and molecular analysis of tissue resected during surgery, there remains high variability within glioma subtypes in terms of response to treatment and outcome. In this study we hypothesized that parameters obtained from magnetic resonance data would be associated with progression-free survival for patients with recurrent low-grade glioma. The values considered were derived from the analysis of anatomic imaging, diffusion weighted imaging, and ¹H magnetic resonance spectroscopic imaging data. Metrics obtained from diffusion and spectroscopic imaging presented strong prognostic capability within the entire population as well as when restricted to astrocytomas, but demonstrated more limited efficacy in the oligodendrogliomas. The results indicate that multi-parametric imaging data may be applied as a non-invasive means of assessing prognosis and may contribute to developing personalized treatment plans for patients with recurrent low-grade glioma.

Keywords: Diffusion; Glioma; MRI; Progression-free survival.

Figure 1

Quantification of MR parameters used in the present analysis. nADC, FA, and FSE intensity percentiles are calculated within the T2 Flair hyperintensity (T2ALL) ROI. In the MRSI image, the blue line delineates voxels with CNI>2, while the green-shaded region (volCNI2) identifies voxels where CNI>2 voxels overlap or are tangent to T2ALL (CNI2s). The integrated sums of CNI (sumCNI) and nLac (sumLac) values from voxels within the CNI2 that were intersecting or at least tangent to the T2ALL were used as measures of abnormal metabolic features of the tumor.

Figure 2

(a) Among astrocytoma patients, patients recurring as grade IV have significantly worse PFS outcome than those recurring as grade II or III (who did not differ significantly). (b) Among oligodendroglioma patients, there is no significant difference in PFS outcome by grade.

Figure 3

(a) Examples of a Grade II→III patient and Grade II→IV patient demonstrating differing nADC and levels of Ki-67. The circled regions represent tissue sample locations. (b) Average nADC histograms for the patient population, consisting of normal-appearing white matter (NAWM) and low and high nADC regions, which were used to produce the nADC colormaps (c) A boxplot comparison of nADC and extent of hypoxia, as denoted by increasing CA9 score, within astrocytoma patients. Values over one inter-quartile range beyond the 25^th or 75^th percentiles were plotted as outliers.

Figure 4

(a) Example of T2 FLAIR, nADC, and nADC colormap images from the exam of a 26 year old Grade II→III patient with a PFS of 360 days. (b) Example of Flair, nADC, and nADC colormap images from the exam of a 28 year old Grade II→III patient with improved PFS outcome of 722 days.