Diagnostic Implications of White Matter Tract Involvement by Intra-axial Brain Tumors

Abstract

Introduction Diffusion tensor imaging (DTI) is being increasingly used during brain tumor surgery. However, there is limited data available on its diagnostic and prognostic value. Our objective was to assess the pattern of involvement of white matter tracts (WMTs) by intra-axial brain tumors on DTI. Secondary objectives were to evaluate implications of involvement of WMT on surgical resection, and the post-operative functional outcome. Methods This was a retrospective study of consecutive patients, who underwent DTI-guided surgery for brain tumors. The involvement of WMTs by tumors on DTI was assessed by a radiologist (who was blind to the pathology) using the Witwer classification. The pathology was reported by histopathologists using the World Health Organization brain tumor classification. Karnofsky Performance Status Scale (KPS) was used for assessing patients’ neurological status at admission, and at follow-up. Results Forty-five (58.4%) out of 77 tumors reviewed caused infiltration of WMTs, whereas only 22 (28.6%) tumors caused displacement of WMTs (p= 0.040). Among 32 cases of astrocytoma, the involvement of WMTs was influenced by the grade of tumor (p= 0.012), as high-grade tumors caused infiltration (19; 59.4%), unlike low-grade tumors that commonly caused displacement (2; 50%). Oligodendrogliomas caused infiltration/disruption of WMTs in most cases, irrespective of the grade (19 out of 25 cases; 76%). At the last follow-up, 27 (35.1%) patients showed improvement in KPS and 14 (18.2%) reported deterioration, while there was no change observed in 36 (46.8%) patients. The infiltration of WMTs was associated with a poor functional outcome. Conclusions High-grade astrocytomas mostly cause infiltration of WMTs, unlike oligodendrogliomas, which often infiltrate WMTs, irrespective of the tumor grade. The infiltration of WMTs is associated with a poor functional outcome at follow-ups.

The Assessment of White Matter Integrity Alteration Pattern in Patients with Brain Tumor Utilizing Diffusion Tensor Imaging: A Systematic Review

“…These selected papers comprised retrospective [1,7,17,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] and prospective studies [18,[36][37][38][39][40]. A total of 1163 patients ranging in age between 2 and 85 were studied in the 25 selected papers.…”

“…The methods of DTI pattern visualization were conducted using intensity of fractional anisotropy (FA) directional color-coded maps [1,7,[20][21][22]24]; some also included diffusion tensor tractography [17,25,26,28,32,33,38]. The utilization of DTI in the assessment and characterization of the WMT alteration patterns is mainly to understand the interaction between the effect of the tumor growth on WMT morphology [1,7,21,25] and to provide information in preoperative and postoperative surgical decision-making [17,23,26,[28][29][30]32,33,36,38] and in the assessment and prediction of postoperative neurological deficits [17,26,28,33,38]. Another objective includes testing the methodology of tractography compared to DEC maps and in the visualizing of the WMT pattern [18,35,40].…”

“…Bakhshi et al (2021) evaluated that the classification of the FA was specified in the exact numerical measurement of the FA for the classification derived by Witwer et al They classified the WMT characterization based on the degree of FA, which, when unaffected, was in the range of 0.163 to 0.286; when displaced, the FA was 0.085 to 0.093; when edematous, the FA was 0.092 to 0.149; infiltrated when the FA in the range of 0.05 to 0.059, finally, disrupted, the FA was less than 0.05 [36]. 4 represents the individual patient assessment of the morphological changes in the white matter tract integrity using the DTI data, DEC maps, and tractography data in relation to the tumor type.…”

“…Here, the classifications of tumor type and tumor grade, tumor location, and the diffusion tensor imaging parameter were specifically studied. In most of the papers studying patterns related to tumor grading, it was found that LGG or benign tumors have a higher association with the displacement pattern compared to HGG or malignant tumors, which were more closely associated with disruption and infiltration [29,32,34,36,38,39]. In addition, Leroy et al (2020) reported that metastases also have more association patterns with displacement [34].…”

“…The only tumor type discussed was by Bakhshi et al (2021), and they found that oligodendrogliomas often infiltrated the white matter tract. It has been argued that the involvement of the WMT in oligodendrogliomas was not associated with the tumor grade [36]. LGG ( 15) HGG ( 36)…”