Improved Delineation of Glioma Margins and Regions of Infiltration with the Use of Diffusion Tensor Imaging: an Image-Guided Biopsy Study

Price SJ, Jena R, Burnet MG, Hutchinson PJ, Dean AF, Pena A, Packard JD, Carpenter TA, Gillard JH.
AJNR Am J Neuroradiol 2006;27:1969–74

Background: Background of this study is the poor prognosis in the treatment of malignant gliomas mainly due to inability to determine exact tumor margins.

Methods: Since malignant gliomas preferentially infiltrate white matter tracks, the authors tried to delineate infiltration using diffusion tensor imaging (DTI) which is sensitive to the directional diffusion of water along white matter tracks. 20 patients were examined by this method including conventional sequences prior to biopsy (biopsies were taken from the center of the target, then at 1-cm intervals along what was considered normal-appearing brain on the basis of biopsy core appearance and conventional MRI). Tumors were: astrocytomas (n = 3), oligodendrogliomas (n = 5), anaplastic oligoastrocytomas (n = 4), glioblastomas (n = 7) and PNET (n = 1). DTI were correlated with histology.

Results: The authors found that DTI is suitable to differentiate gross tumor from infiltration with a sensitivity of 98% and a specificity of 81%. T2-weighted images failed to identify tumor margins in half of the cases.

Conclusion: The authors conclude that DTI can better delineate tumor margins which might help to better target radiation therapy.

Comment

No question about the fact that better imaging techniques are requested for a better delineation of primary brain tumor margins. This article is another important step toward a solution for this problem. Using DTI in gliomas seems very promising. DTI was already effectively used to distinguish low and high grade glioma (Inoue et al., Clin Neurol Neurosurg 2005). We follow the authors’ conclusion: combining now all information about white matter disruption from DTI with metabolic information from MR spectroscopy might allow a better delineation of tumor infiltration, hence a better targeted local treatment. Future studies should focus on a multimodal approach (Goebell et al., AJNR Am J Neuroradiol 2006).

References

1. Inoue T, Ogasawara K, Beppu T, Ogawa A, Kabasawa H. Diffusion tensor imaging for preoperative evaluation of tumor grade in gliomas. Clin Neurol Neurosurg 2005;107:174–80.
2. Goebell E, Fiehler J, Ding XQ, Paustenbach S, Nietz S, Heese O, Kucinski T, Hagel C, Westphal M, Zeumer H. Disarrangement of fiber tracts and decline of neuronal density correlate in glioma patients – a combined diffusion tensor imaging and 1H-MR spectroscopy study. AJNR Am J Neuroradiol 2006;27:1426–31. (submitted October 23, 2006)

I. Wanke, Essen