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Published on: January 14, 2014
MRI features predict tumor grade in isocitrate dehydrogenase (IDH)-mutant astrocytoma and oligodendroglioma
David A Joyner1, John Garrett1, Prem P Batchala1
1Department of Radiology and Medical Imaging, University of Virginia Health System, Box 800170, Charlottesville, VA, 22908, USA.
Purpose:
Nearly all literature for predicting tumor grade in astrocytoma and oligodendroglioma pre-dates the molecular classification system. We investigated the association between contrast enhancement, ADC, and rCBV with tumor grade separately for IDH-mutant astrocytomas and molecularly-defined oligodendrogliomas.
Methods:
For this retrospective study, 44 patients with IDH-mutant astrocytomas (WHO grades II, III, or IV) and 39 patients with oligodendrogliomas (IDH-mutant and 1p/19q codeleted) (WHO grade II or III) were enrolled. Two readers independently assessed preoperative MRI for contrast enhancement, ADC, and rCBV. Inter-reader agreement was calculated, and statistical associations between MRI metrics and WHO grade were determined per reader.
Results:
For IDH-mutant astrocytomas, both readers found a stepwise positive association between contrast enhancement and WHO grade (Reader A: OR 7.79 [1.97, 30.80], p = 0.003; Reader B: OR 6.62 [1.70, 25.82], p = 0.006); both readers found that ADC was negatively associated with WHO grade (Reader A: OR 0.74 [0.61, 0.90], p = 0.002); Reader B: OR 0.80 [0.66, 0.96], p = 0.017), and both readers found that rCBV was positively associated with WHO grade (Reader A: OR 2.33 [1.35, 4.00], p = 0.002; Reader B: OR 2.13 [1.30, 3.57], p = 0.003). For oligodendrogliomas, both readers found a positive association between contrast enhancement and WHO grade (Reader A: OR 15.33 [2.56, 91.95], p = 0.003; Reader B: OR 20.00 [2.19, 182.45], p = 0.008), but neither reader found an association between ADC or rCBV and WHO grade.
Conclusions:
Contrast enhancement predicts WHO grade for IDH-mutant astrocytomas and oligodendrogliomas. ADC and rCBV predict WHO grade for IDH-mutant astrocytomas, but not for oligodendrogliomas.
Insights
Contrast enhancement is a reliable MRI marker for predicting tumor grade in both IDH-mutant astrocytomas and oligodendrogliomas. Apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) also predict grade in astrocytomas.
Area of Science:
- Neuro-oncology
- Radiology
- Molecular Pathology
Background:
- Existing literature on predicting tumor grade predates current molecular classification systems.
- Accurate tumor grading is crucial for guiding treatment and prognosis in brain tumors.
- Molecular classification, particularly IDH mutation status and 1p/19q codeletion, refines glioma diagnosis.
Purpose of the Study:
- To investigate the association between MRI metrics (contrast enhancement, ADC, rCBV) and tumor grade in IDH-mutant astrocytomas.
- To assess the same MRI metrics' association with tumor grade in molecularly-defined oligodendrogliomas.
- To determine if MRI findings can predict tumor grade within these specific molecular subgroups.
Main Methods:
- Retrospective analysis of preoperative MRI scans from 44 patients with IDH-mutant astrocytomas (WHO grades II-IV) and 39 with oligodendrogliomas (WHO grades II-III).
- Two independent readers assessed contrast enhancement, ADC, and rCBV.
- Statistical analysis determined associations between MRI metrics and WHO grade, with inter-reader agreement assessed.
Main Results:
- For IDH-mutant astrocytomas, contrast enhancement, ADC, and rCBV were all significantly associated with WHO grade.
- For oligodendrogliomas, contrast enhancement showed a significant positive association with WHO grade.
- Neither ADC nor rCBV were found to be associated with WHO grade in oligodendrogliomas.
Conclusions:
- Contrast enhancement on MRI is a valuable predictor of WHO tumor grade for both IDH-mutant astrocytomas and oligodendrogliomas.
- ADC and rCBV are useful for grading IDH-mutant astrocytomas but not oligodendrogliomas.
- These findings highlight the differential utility of MRI metrics in predicting tumor grade based on molecular glioma subtypes.
