MR Elastography Analysis of Glioma Stiffness and IDH1-Mutation Status

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Tumor stiffness properties were prospectively quantified in 18 patients with histologically proved gliomas using MR elastography. Images were acquired on a 3T MR imaging unit with a vibration frequency of 60 Hz. Tumor stiffness was compared with unaffected contralateral white matter, across tumor grade, and by IDH1-mutation status. Gliomas were softer than healthy brain parenchyma, 2.2kPa compared with 3.3kPa, with grade IV tumors softer than grade II. MR elastography demonstrated that not only were gliomas softer than normal brain but the degree of softening was directly correlated with tumor grade and IDH1-mutation status.

Abstract

Figure 4 from paper
Stiffness heterogeneity of gliomas. Noncontrast, axial MRE magnitude images (left column), shear wave images (middle column), and elastograms (right column) for 2 patients with grade III gliomas. Images in the top row are from an oligodendroglioma with an IDH1–R132H mutation with |G*| = 3.3 kPa (a 31-year-old man), while the bottom row is from a diffuse astrocytoma with wild type IDH1 with |G*| = 1.7 kPa (a 44-year-old woman).

BACKGROUND AND PURPOSE

Our aim was to noninvasively evaluate gliomas with MR elastography to characterize the relationship of tumor stiffness with tumor grade and mutations in the isocitrate dehydrogenase 1 (IDH1) gene.

MATERIALS AND METHODS

Tumor stiffness properties were prospectively quantified in 18 patients (mean age, 42 years; 6 women) with histologically proved gliomas using MR elastography from 2014 to 2016. Images were acquired on a 3T MR imaging unit with a vibration frequency of 60 Hz. Tumor stiffness was compared with unaffected contralateral white matter, across tumor grade, and by IDH1-mutation status. The performance of the use of tumor stiffness to predict tumor grade and IDH1 mutation was evaluated with the Wilcoxon rank sum, 1-way ANOVA, and Tukey-Kramer tests.

RESULTS

Gliomas were softer than healthy brain parenchyma, 2.2 kPa compared with 3.3 kPa (P< .001), with grade IV tumors softer than grade II. Tumors with an IDH1 mutation were significantly stiffer than those with wild type IDH1, 2.5 kPa versus 1.6 kPa, respectively (P = .007).

CONCLUSIONS

MR elastography demonstrated that not only were gliomas softer than normal brain but the degree of softening was directly correlated with tumor grade and IDH1-mutation status. Noninvasive determination of tumor grade and IDH1 mutation may result in improved stratification of patients for different treatment options and the evaluation of novel therapeutics. This work reports on the emerging field of “mechanogenomics”: the identification of genetic features such as IDH1mutation using intrinsic biomechanical information.

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MR Elastography Analysis of Glioma Stiffness and IDH1-Mutation Status
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jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.