Patterns of Recurrence Analysis in Newly Diagnosed Glioblastoma Multiforme After Three-Dimensional Conformal Radiation Therapy With Respect to Pre–Radiation Therapy Magnetic Resonance Spectroscopic Findings

Abstract

Purpose-To determine whether the combined MRI and MR spectroscopy imaging (MRSI) prior to radiation therapy (RT) is valuable for RT target definition, and to evaluate the feasibility of replacing the current definition of uniform margins by custom shaped margins based on the information from MRI and MRSI.Methods and Materials-Twenty three GBM patients underwent MRI and MRSI within 4 weeks after surgery but before the initiation of RT and at two month follow-up (FU) intervals thereafter. MRSI data were quantified on the basis of a Choline-to-NAA Index (CNI) as a measure of spectroscopic abnormality. A combined anatomic and metabolic ROI (MRI/S) consisting of T2-weighted hyperintensity, contrast enhancement (CE), resection cavity and CNI2 based on the pre-RT imaging was compared to CNI2 extent and RT dose distribution. The spatial relationship of the pre-RT MRI/S and the RT dose volume was compared to the extent of CE at each FU.Results-Nine patients showed new or increased CE during FU, and 14 patients were either stable or had decreased CE. New or increased areas of CE occurred within CNI2 that was covered by 60 Gy in six patients and within the CNI2 that was not entirely covered by 60 Gy in three patients. New or increased CE resided within the pre-RT MRI/S lesion in 89 % (8/9) of the patients with new or increased CE.Conclusion-These data indicate that the definition of RT target volumes according to the combined morphologic and metabolic abnormality may be sufficient for RT targeting.

Association of early changes in1H MRSI parameters with survival for patients with newly diagnosed glioblastoma receiving a multimodality treatment regimen

“…24 Using the MRSI data to define the spatial extent of tumor would change the target for RT, [25][26][27] alter the definition of response to therapy, and assist in distinguishing residual and recurrent tumor from nonspecific treatment effects. [28][29][30] Several different ways of representing the metabolic data were considered in this study. The CNI was developed and validated using image-guided tissue samples several years ago.…”

“…1-3 provide examples of how using this metric as a color overlay can improve the visualization of the metabolic lesion. This is of particular interest for interpreting serial changes in tumor burden 7,28,29 and avoiding complications associated with pseudoprogression and pseudoresponse. 11 Table 2 Temporal changes in anatomic lesion volumes and metabolic imaging parameters for patients with scans at all 3 time points, and those with OS either less than or greater than the median value of 449 days.…”

Pattern recognition of MRSI data shows regions of glioma growth that agree with DTI markers of brain tumor infiltration

“…Tumor recurrence was found to occur along directions where the region of abnormal isotropic diffusion extended beyond the region of abnormal anisotropy. Tissue metabolic profiles obtained by magnetic resonance spectroscopic imaging (MRSI) have been used in a number of studies to delineate abnormal (i.e., containing tumor) regions that extend beyond the lesion defined by T 2 -weighted MRI (4)(5)(6)(7)(8). A reduced absolute N-acetyl-aspartate concentration (8) or elevated choline to N-acetyl-aspartate ratio has been used to define the infiltrative tumor region (4,5).…”

Glioblastoma multiforme: emerging treatments and stratification markers beyond new drugs

“…76 By this means, Parra et al 77 compared metabolic tumour volumes with standard RT volumes using an advanced volumetric three-dimensional (3D) MRSI approach and found in an observational study of n 5 19 patients with GBM that on average, one-third Cho-defined volume was not covered by the CTV receiving 60 Gy. Park et al 78 studied the CNI2 volume at therapy initiation in another observational study of n 5 23 patients with GBM and showed that one-third of recurrent-enhancing GBM volume within this metabolically active tumour region was not initially covered by the 60-Gy RT target. Moreover, the early change of the Cho-to-NAA index during RT has been shown to predict early progression within an observational study of GBM where the voxel-based analysis of 3D MRSI data retrospectively revealed a significant increase in median Cho/NAA in the group of patients with early recurrent tumour.…”