Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery

Neuro-Oncology, Feb 2012

Diffusion tensor imaging (DTI) tractography enables the in vivo visualization of the course of white matter tracts inside or around a tumor, and it provides the surgeon with important information in resection planning. This study is aimed at assessing the ability of preoperative DTI tractography in predicting the extent of the resection achievable in surgical removal of gliomas. Patients with low-grade gliomas (LGGs; 46) and high-grade gliomas (HGGs; 27) were studied using a 3T scanner according to a protocol including a morphological study (T2, fluid-attenuated inversion-recovery, T1 sequences) and DTI acquisitions (b = 1000 s/mm2, 32 gradient directions). Preoperative tractography was performed off-line on the basis of a streamline algorithm, by reconstructing the inferior fronto-occipital (IFO), the superior longitudinal fascicle (SLF), and the corticospinal tract (CST). For each patient, the relationship between each bundle reconstructed and the lesion was analyzed. Initial and residual tumor volumes were measured on preoperative and postoperative 3D fluid-attenuated inversion-recovery images for LGGs and postcontrast T1-weighted scans for HGGs. The presence of intact fascicles was predictive of a better surgical outcome, because these cases showed a higher probability of total resection than did subtotal and partial resection. The presence of infiltrated or displaced CST or infiltrated IFO was predictive of a lower probability of total resection, especially for tumors with preoperative volume <100 cm3. DTI tractography can thus be considered to be a promising tool for estimating preoperatively the degree of radicality to be reached by surgical resection. This information will aid clinicians in identifying patients who will mostly benefit from surgery.

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Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery

Advance Access publication October Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery Antonella Castellano 0 1 2 Lorenzo Bello 0 1 2 Caterina Michelozzi 0 1 2 Marcello Gallucci 0 1 2 Enrica Fava 0 1 2 Antonella Iadanza 0 1 2 Marco Riva 0 1 2 Giuseppe Casaceli 0 1 2 Andrea Falini 0 1 2 0 (C.M.); and Department of Psychology, Universita` di Milano-Bicocca (M.G.) , Milan , Italy 1 A.F.); Neurosurgery, Department of Neurological Sciences, Universit a` degli Studi di Milano , and Istituto 2 Neuroradiology Unit and CERMAC, Scientific Institute and Universita` Vita-Salute San Raffaele (A.C., A.I. Clinico Humanitas (L.B., E.F., M.R., G.C.); Institute of Radiological Sciences, Universita` degli Studi di Milano considered to be a promising tool for estimating preoperatively the degree of radicality to be reached by surgical resection. This information will aid clinicians in identifying patients who will mostly benefit from surgery. Diffusion tensor imaging; DTI tractography; extent of resection; glioma surgery; presurgical planning - Diffusion tensor imaging (DTI) tractography enables the in vivo visualization of the course of white matter tracts inside or around a tumor, and it provides the surgeon with important information in resection planning. This study is aimed at assessing the ability of preoperative DTI tractography in predicting the extent of the resection achievable in surgical removal of gliomas. Patients with low-grade gliomas (LGGs; 46) and high-grade gliomas (HGGs; 27) were studied using a 3T scanner according to a protocol including a morphological study (T2, fluid-attenuated inversion-recovery, T1 sequences) and DTI acquisitions (b 5 1000 s/mm2, 32 gradient directions). Preoperative tractography was performed off-line on the basis of a streamline algorithm, by reconstructing the inferior fronto-occipital (IFO), the superior longitudinal fascicle (SLF), and the corticospinal tract (CST). For each patient, the relationship between each bundle reconstructed and the lesion was analyzed. Initial and residual tumor volumes were measured on preoperative and postoperative 3D fluidattenuated inversion-recovery images for LGGs and postcontrast T1-weighted scans for HGGs. The presence of intact fascicles was predictive of a better surgical outcome, because these cases showed a higher probability of total resection than did subtotal and partial resection. The presence of infiltrated or displaced CST or infiltrated IFO was predictive of a lower probability of total resection, especially for tumors with preoperative volume <100 cm3. DTI tractography can thus be Cinvolving both cortical and subcortical strucerebral gliomas are highly invasive neoplasms tures. These tumors are frequently located in or close to eloquent areas, and they are characterized by a diffuse and infiltrative pattern of growth, because invasive glioma cells are frequently found to migrate along myelinated fiber tracts of white matter (WM).1 WM is crucial for brain function, and its pathological involvement correlates with neurological or neuropsychological findings;2,3 however, low-grade gliomas (LGGs) typically grow slowly and often spare neural function as they infiltrate eloquent brain areas, and patients usually have normal neurological examination findings.4 Diffusion tensor imaging (DTI) tractography is widely applied in patients with glioma,5,6 because this advanced magnetic resonance (MR) technique is the only noninvasive method allowing the in vivo identification of the trajectories of WM tracts adjacent to or inside the tumor.6 DTI tractography can show the various effects exerted by the tumor on WM tracts, providing information about the normal course, the displacement, or the infiltration of the fascicles.5 – 7 Intraoperative subcortical brain mapping studies8,9 recently showed that DTI tractography data are reliable and accurate in describing the trajectories of the tracts and their modifications induced by the lesions, because tracking results correlated with those obtained by direct electrical stimulation. At present, DTI tractography is specifically used as a preoperative examination to improve neurosurgical planning,9 – 13 and it is usually uploaded to the neuronavigation system together with morphological and functional images.14 This means that patients undergo DTI tractography when a surgical procedure has already been planned. The aim of this study was to investigate whether DTI tractography could be useful, even a step earlier, as a tool to select which patients will benefit the most from surgery, obtaining a total resection, and thus, having longer overall survival.15 – 17 The major WM tracts responsible for eloquent functions were preoperatively reconstructed in patients with supratentorial brain gliomas involving speech or motor areas or pathways. The corticospinal tract (CST) and 2 of the main fiber bundles involved in the phonologic and semantic lo (...truncated)


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Antonella Castellano, Lorenzo Bello, Caterina Michelozzi, Marcello Gallucci, Enrica Fava, Antonella Iadanza, Marco Riva, Giuseppe Casaceli, Andrea Falini. Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery, Neuro-Oncology, 2012, pp. 192-202, 14/2, DOI: 10.1093/neuonc/nor188