Q-Ball high-resolution fiber tractography: Optimizing corticospinal tract delineation near gliomas and its role in the prediction of postoperative motor deficits– A proof of concept study

Introduction

After resection of eloquent gliomas, impacting motor pathways, patients frequently harbour pronounced motor deficits (MD), predominantly attributed to damage to the corticospinal tract (CST).

Research question

This study compares the results of conventional DTI-FT and q-ball (QBI)-high resolution FT with patient's postoperative morbidity, relating postoperative MD with the nearest distance from the lesion to the CST (nD-LCST).

Materials and methods

In this ongoing prospective trial, we utilized probabilistic High-Resolution Fiber Tracking (HRFT) through q-ball imaging (QBI-FT) and conventional Diffusion Tensor Imaging Fiber Tracking (DTI-FT), based on equal and standard diffusion-weighted MRI. Our analysis focused on the normalized Distance from the lesion to the CST-FT (nD-LCST), compared with MD evaluated via standardized clinical examination.

Results

Post-surgery, 4 patients developed new MD or deteriorated respectively. Among these, one patient was diagnosed with glioblastoma, one with diffuse astrocytoma, one with anaplastic astrocytoma, and one with oligodendroglioma. QBI-FT analysis revealed that patients with MD had a significantly lower median nD-LCST (−0.4 IQR = 2.1), in contrast to those without MD (8.4 IQR = 3.9; p = 0.029). Median values of QBI-FT were located within the tumor outlines, when MD deteriorated. Patients with postoperatively impaired MD had larger tumor volumes compared to those without MD.

Discussion and conclusion

Our preliminary findings suggest that QBI-FT may offer advantages over DTI-FT in predicting postoperative motor deficits, potentially enhancing neurosurgical planning. However, due to the small sample size of our study, these results are exploratory, and further research with larger patient populations is necessary to confirm the benefits of QBI-FT. QBI-FT shows promise as a complementary tractography technique suitable for clinical purposes alongside standard DTI-FT.