Perfusion, diffusion and spectroscopy values in newly diagnosed cerebral gliomas

Abstract

Purpose To evaluate perfusion, diffusion, and spectroscopy values in enhancing and non-enhancing lesions for patients with newly diagnosed gliomas of different grades. Materials and Methods Sixty-seven patients with newly diagnosed glioma were entered into the study 20 grade II, 26 grade III and 21 grade IV. MR data were acquired at 1.5T and included diffusion weighted images (59/67 patients), dynamic perfusion weighted images (30/67 patients) and 3D H-1 MR spectroscopy (64/67 patients). Enhancing and non-enhancing lesions were delineated by a neuroradiologist and applied to maps of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), relative anisotropy (RA) and metabolite intensities. Results The median rCBV within enhancing regions of grade IV gliomas was significantly elevated relative to enhancing regions in grade III gliomas and normal brain. ADC was elevated relative to normal brain, but was not significantly different between grades or between enhancing and non-enhancing regions. The RA was higher in the non-enhancing region of grade IV gliomas relative to grade II and grade III. Levels of lactate plus lipid were significantly elevated in grade IV relative to grade II and grade III gliomas. Both enhancing and non-enhancing regions in grade IV gliomas showed significant correlations between CBV, ADC and choline levels. Conclusion The data were consistent with grade IV gliomas having higher membrane turnover, increased cell density and increased vascularity within enhancing lesions. Analysis of the correlations among parameters within grade IV gliomas suggested that high vascularity (high rCBV) was correlated with increased cellularity (low ADC) and increased membrane turnover (high choline) in these lesions. The non-enhancing region of grades II and III gliomas had MR parameters consistent with increased cellularity and/or membrane turnover.

Quantitative apparent diffusion coefficients in the characterization of brain tumors and associated peritumoral edema

“…In a recent paper, Chang et al (187) have shown that while this may be the case for area of macroscopic tumor within the enhancing volume of grade IV glioma, it is not consistent with the values in grade II and grade III glioma. Catalaa et al (204) observed a negative correlation between mean ADC and mean Cho for patients with newly diagnosed grade IV gliomas, but not for grade II or grade III gliomas. Khayal et al (205) were unable to detect a correlation between Cho levels in the contrast enhancement or necrotic core and ADC in grade IV gliomas, but they found a negative correlation between median Cho and ADC in the non-enhancing lesion and the overall T2-hyperintensity.…”

Comments and controversies: Magnetic resonance spectroscopy and gliomas

“…However, often a high-grade glioma may be mistaken for a low-grade glioma when it demonstrates minimal edema, no contrast material enhancement, no necrosis, and no mass effect. Moreover, large cerebral gliomas are often histopathologically heterogeneous and may have components of varying grades of malignancy within them [1] . Therefore, accurate preoperative grading of gliomas and planning of adequate treatment strategies are often difficult with conventional MR imaging alone.…”

Analysis of Metabolic Indices in Regions of Abnormal Perfusion in Patients with High-Grade Glioma

“…This finding agreed with previously published data showing no significant correlation between volumes of elevated lactate and any morphologic abnormality. 20 Our results suggest that a reduction in creatine levels and the presence of regions with abnormal vasculature may be considered as noninvasive markers of tumor progression from grade III to grade IV gliomas. Increased cellular proliferation, as indicated by elevated choline in the aPH region of grade III gliomas, may initially cause dilation of existing blood vessels and/or the formation of new ones.…”

“…Contralateral normal tissue was also included as a reference for postprocessing of metabolites and region definition. 20 K-space sampling was restricted to the central ellipsoidal region within a 12 ϫ 12 ϫ 8 phase-encode matrix to shorten the acquisition time to approximately half that of the full k-space sampling. 33 This technique allowed separation of lactate from lipid within the same total acquisition time (ϳ17 minutes).…”

“…Various groups have compared relative cerebral blood volume (rCBV) and/or permeability values derived from DSC-MR imaging with metabolic indices in low-and high-grade brain tumors. [17][18][19][20][21][22] However, these studies usually analyze only the central contrast-enhancing portion of the tumor or region with maximal rCBV and do not use spectroscopic imaging sequences sensitive to lactate detection. 19,[23][24][25][26][27][28][29] Previous studies have shown that voxel-by-voxel comparison of percent recovery and peak-height values obtained from a nonparametric model can be easily used to characterize independently regions of BBB breakdown and increased vessel volume due to angiogenesis.…”