Improved Brain Tumor Classification by Sodium MR Imaging: Prediction of IDH Mutation Status and Tumor Progression.
OBJECTIVE
MR imaging in neuro-oncology is challenging due to inherent ambiguities in proton signal behavior. Sodium-MR imaging may substantially contribute to the characterization of tumors because it reflects the functional status of the sodium-potassium pump and sodium channels.


METHODS
Sodium-MR imaging data of patients with treatment-naïve glioma WHO grades I-IV (n = 34; mean age, 51.29 ± 17.77 years) were acquired by using a 7T MR system. For acquisition of sodium-MR images, we applied density-adapted 3D radial projection reconstruction pulse sequences. Proton-MR imaging data were acquired by using a 3T whole-body system.


RESULTS
We demonstrated that the initial sodium signal of a treatment-naïve brain tumor is a significant predictor of isocitrate dehydrogenase (IDH) mutation status (P < .001). Moreover, independent of this correlation, the Cox proportional hazards model confirmed the sodium signal of treatment-naïve brain tumors as a predictor of progression (P = .003). Compared with the molecular signature of IDH mutation status, information criteria of model comparison revealed that the sodium signal is even superior to IDH in progression prediction. In addition, sodium-MR imaging provides a new approach to noninvasive tumor classification. The sodium signal of contrast-enhancing tumor portions facilitates differentiation among most glioma types (P < .001).


CONCLUSIONS
The information of sodium-MR imaging may help to classify neoplasias at an early stage, to reduce invasive tissue characterization such as stereotactic biopsy specimens, and overall to promote improved and individualized patient management in neuro-oncology by novel imaging signatures of brain tumors.
From the Departments of Neuroradiology (A.B., M.B., J.K.) Departments of Radiology (A.B., J.K.) armin.biller@med.uni-heidelberg.de.
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Biller
Department of Biological Psychology and Neuropsychology (S.B.), University of Hamburg, Hamburg, Germany.
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S
Badde
Medical Physics in Radiology (A.N., N.B.), German Cancer Research Centre (DKFZ), Heidelberg, Germany.
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A
Nagel
Neurosurgery (J.-O.N.).
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Neumann
Neuro-Oncology (W.W., A.H.).
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http://orcid.org/0000-0001-5681-7771
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Wick
Neuro-Oncology (W.W., A.H.).
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Hertenstein
From the Departments of Neuroradiology (A.B., M.B., J.K.).
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http://orcid.org/0000-0002-9094-6769
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Bendszus
Neuropathology (F.S.).
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Sahm
Medical Physics in Radiology (A.N., N.B.), German Cancer Research Centre (DKFZ), Heidelberg, Germany.
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Benkhedah
From the Departments of Neuroradiology (A.B., M.B., J.K.) Multidimensional Image Processing Group (J.K.), HCI/IWR, University of Heidelberg, Heidelberg, Germany Departments of Radiology (A.B., J.K.).
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Kleesiek
D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000145:classification* / Q000235:genetics / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005910:Glioma / Q000145:classification* / Q000235:genetics / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016016:Proportional Hazards Models; D012964:Sodium
D012964:Sodium; D007521:Isocitrate Dehydrogenase