Integrating Functional MRI Information into Radiotherapy Planning of CNS Tumors-Early Experiences

Abstract

The purpose of our study was to examine the integration of functional MRI (fMRI) information into 3D based planning process of the central nervous system (CNS) malignancies. Between 01.01.2008 and 01.12.2008 four patients with astrocytoma were enrolled to this study. Before the planning process conventional planning CT, postoperative MR and individual functional MRI examinations were delivered. For the functional MRI examination the following four types of stimulus were applied: acoustic, visual, somatosensory and numeral. Three different theoretical planning situations were applied and compared: 3D conformal plan without fMRI information, 3D conformal plan with fMRI information and IMRT plan with fMRI information. For plan comparison DVH analysis, and NTCP model were used. fMRI based OR definition resulted in 4 additional OR's in the contouring process. As these cases demonstrate, an average of 50% dose reduction was achieved in OR, OR2 and OR3 with IMRT and fMRI based 3D planning, especially in case of midline localization and big tumor extent. IMRT provides additional sparing effect in the optic tract and brainstem, especially for localizations close to the midline. Our results demonstrated that using fMRI information in conventional 3D based treatment planning potentially benefits significant dose reduction in critical organs, with no compromise in PTV coverage. fMRI can be widely used even in low grade cases (long life expectancies, lower acute and late toxicity in radiotherapy) and in cases with high grade astrocytomas or metastases (higher dose to PTV with better risk organ sparing in radiotherapy).

Integrating functional MRI information into conventional 3D radiotherapy planning of CNS tumors. Is it worth it?

“…Our initial experiences of fMRI-based treatment planning of CNS tumours were published after a feasibility study (experiments based on data from four patients) [4].…”

Population‐Level Correction of Systematic Motion Artifacts in fMRI in Patients with Ischemic Stroke

“…This includes cumulative (RMS.scan, RMS.task, and RMS.rest) and statistical (RMS.diff, RMS.dyn) parameters. After a correlation analysis between patients' physiological scores and motion parameters (7), we have selected RMS.diff to represent intersubject motion variability in the corrected population-level model (STIM + RMS.diff) (8). REG = registration-based motion correction; M6 = six motion parameters; CompCor = component-based noise correction; STIM = stimulus group-mean model; RMS = root-mean-squared; RMS.scan = total displacement through the session; RMS.task = movement during task; RMS.rest = movement during rest; RMS.diff = statistical difference between head motion during active and passive periods; RMS.dyn = ratio of movement in task and rest periods; ROI = region of interest; FLIRT = FMRIB's Linear Image Registration Tool.…”

“…2,3 Noninvasive mapping of brain activity with blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has become a key technology in many clinical fields, including neuropsychology, 4 neurororadiology, 5 neurosurgery, 6 and radiotherapy. 7 It also has a major role in evaluating poststroke recovery and rehabilitation 8,9 and in investigating the relationship between neural reorganization and functional recovery after stroke. 10 In stroke rehabilitation, the poststroke motor dysfunction and the corresponding potential cerebral reorganization can be characterized by using active and passive movement-based fMRI experiments.…”

Prevention of radiotherapy-induced neurocognitive dysfunction in survivors of paediatric brain tumours: the potential role of modern imaging and radiotherapy techniques

“…In a feasibility study of 4 patients with low-grade glioma, Kovacs et al co-registered fMRI following acoustic, visual, somatosensory and numeral stimuli to a planning CT scan (89). The study showed that with fMRI based 3D conformal planning, radiotherapy dose to the superior and inferior temporal gyrus and lingual gyrus could be reduced by an average of 50%.…”