Extent of resection of peritumoral diffusion tensor imaging–detected abnormality as a predictor of survival in adult glioblastoma patients

Abstract

OBJECTIVE Diffusion tensor imaging (DTI) has been shown to detect tumor invasion in glioblastoma patients and has been applied in surgical planning. However, the clinical value of the extent of resection based on DTI is unclear. Therefore, the correlation between the extent of resection of DTI abnormalities and patients' outcome was retrospectively reviewed. METHODS A review was conducted of 31 patients with newly diagnosed supratentorial glioblastoma who underwent standard 5-aminolevulinic acid-aided surgery with the aim of maximal resection of the enhancing tumor component. All patients underwent presurgical MRI, including volumetric postcontrast T1-weighted imaging, DTI, and FLAIR. Postsurgical anatomical MR images were obtained within 72 hours of resection. The diffusion tensor was split into an isotropic (p) and anisotropic (q) component. The extent of resection was measured for the abnormal area on the p, q, FLAIR, and postcontrast T1-weighted images. Data were analyzed in relation to patients' outcome using univariate and multivariate Cox regression models controlling for possible confounding factors including age, O-methylguanine-DNA-methyltrans-ferase methylation status, and isocitrate dehydrogenase-1 mutation. RESULTS Complete resection of the enhanced tumor shown on the postcontrast T1-weighted images was achieved in 24 of 31 patients (77%). The mean extent of resection of the abnormal p, q, and FLAIR areas was 57%, 83%, and 59%, respectively. Increased resection of the abnormal p and q areas correlated positively with progression-free survival (p = 0.009 and p = 0.006, respectively). Additionally, a larger, residual, abnormal q volume predicted significantly shorter time to progression (p = 0.008). More extensive resection of the abnormal q and contrast-enhanced area improved overall survival (p = 0.041 and 0.050, respectively). CONCLUSIONS Longer progression-free survival and overall survival were seen in glioblastoma patients in whom more DTI-documented abnormality was resected, which was previously shown to represent infiltrative tumor. This highlights the potential usefulness and the importance of an extended resection based on DTI-derived maps.

Current Clinical Brain Tumor Imaging

“…89,90 Often, tumor boundaries are not clearly delineated by conventional imaging, and DTI tractography may improve border characterization leading to greater resection and improved outcomes. 87,91 The identification and preservation of white matter tracts is also important in preserving the neurological functional integrity of patients undergoing resection of lesions near eloquent cortex.…”

Modelling MR and clinical features in grade II/III astrocytomas to predict IDH mutation status

“…It is wellestablished in high grade gliomas that the surrounding nonenhancing region represented by T2W and FLAIR signal abnormality is a mixture of infiltrative tumour and oedema [10]. In GBM, multiple studies investigating the qualitative extent of peritumoural oedema/nonenhancing disease have shown that the presence and extent of FLAIR signal abnormality is a negative prognostic factor [11][12][13] with increased resection of FLAIR abnormalities correlating positively with progressionfree survival [14]. The inclusion of FLAIR assessment in the recently updated RANO criteria also highlights the importance of FLAIR signal in monitoring treatment response [15].…”

Global effects of focal brain tumours on functional complexity and network robustness

“…A new philosophy of supra-marginal resection has entered the vocabulary of neuro-oncology whereby surgical excision is extended beyond the confines of a lesion as it is visible on standard structural imaging. This paradigm is based on identification of tumour infiltration beyond the contrast enhancing margin (Miwa et al, 2004;Price and Gillard, 2011;Price et al, 2007;Witwer et al, 2002), fluorescence-guided imaging that can identify potentially infiltrated brain at surgery (Floeth et al, 2011;Stummer et al, 2006), clinical studies correlating extended resections with improved survival (Aldave et al, 2013;Ius et al, 2011;Li et al, 2016;Yan et al, 2017), and potentially improved effectiveness of adjuvant therapies (Stummer et al, 2012). However, extending surgery outside the lesion margins comes with the risk of intruding on eloquent brain and consequently the potential of neurological impairment.…”