Prognostic Value of Perfusion MR Imaging of High-Grade Astrocytomas: Long-Term Follow-Up Study

Abstract

BACKGROUND AND PURPOSE:Although the prognostic value of perfusion MR imaging in various gliomas has been investigated, that in high-grade astrocytomas alone has not been fully evaluated. The purpose of this study was to evaluate retrospectively whether the tumor maximum relative cerebral blood volume (rCBV) on pretreatment perfusion MR imaging is of prognostic value in patients with high-grade astrocytoma.

Correlations between Perfusion MR Imaging Cerebral Blood Volume, Microvessel Quantification, and Clinical Outcome Using Stereotactic Analysis in Recurrent High-Grade Glioma

“…44 Our study provides a direct histologic microvascular correlate to rCBV, which helps to support the alternative hypothesis that rCBV can predict survival beyond grade alone. 20,42,43 Specifically, we validate the hypothesis that rCBV reflects tissue MVA, which permits the unification of otherwise separate sources of literature: those studies correlating survival with histologic MVA quantification 1,4,[8][9][10] and those with rCBV measurement. 16,20,42,43 Unlike previous studies that restricted analyses to tumors of identical grade, the size of our cohort was too small to separately assess survival in grade III and grade IV tumors; however, our purpose in this study was not to replicate what has been shown in prior studies.…”

“…20,42,43 Specifically, we validate the hypothesis that rCBV reflects tissue MVA, which permits the unification of otherwise separate sources of literature: those studies correlating survival with histologic MVA quantification 1,4,[8][9][10] and those with rCBV measurement. 16,20,42,43 Unlike previous studies that restricted analyses to tumors of identical grade, the size of our cohort was too small to separately assess survival in grade III and grade IV tumors; however, our purpose in this study was not to replicate what has been shown in prior studies. Rather, the goals of our correlation analyses were to uniquely illustrate the following: 1) rCBV and MVA measures, taken from the same Fig 2. A, Measures of rCBV show poor correlation with MVD under conditions of high vessel size heterogeneity (n ϭ 18, black data series) but good correlation (red data series) when limiting analysis to homogeneous vessel size (n ϭ 20, red series).…”

“…[16][17][18][19] However, recent studies have proposed an alternative hypothesis, that rCBV predicts outcome independent of histologic grade. 20,42,43 Law et al 20 and Hirai et al 43 separately reported that rCBV could distinguish survival differences among tumors that were diagnosed histologically as the same grade; however, unlike histology-based studies that correlate MVA and grade within the same tissue sample, none of the imaging-based studies to date have measured rCBV from locations that spatially corresponded with the areas of histologic diagnosis. Thus, these imaging-based studies could not exclude the possibility of sampling errors and histologic misgrading that might influence survival differences within their cohorts.…”

Prognostic Value of Dynamic Susceptibility Contrast-Enhanced and Diffusion-Weighted MR Imaging in Patients with Glioblastomas

“…Conventional imaging characteristics of GBM, including location, size, and degree of enhancement; necrosis; and extent of edema, have been studied for prediction of survival. [9][10][11][29][30][31][32][33][34][35][36] Although contrast enhancement is generally used to estimate the extent of the tumor, it is clear from the literature that conventional radiologic findings, such as the absence of contrast enhancement, are not only poor predictors of tumor grade but may or may not be prognostic factors for either survival or progression-free survival.…”

The Blood Oxygen Level–Dependent Functional MR Imaging Signal Can Be Used to Identify Brain Tumors and Distinguish Them from Normal Tissue

“…Several recent studies have demonstrated differences in blood flow between tumors and normal brain and that hypoxia, cerebral blood volume, and blood flow correlate with tumor grade and patient outcome. [20][21][22][23] In this study, we focused on 2 questions: Do brain tumors have a unique BOLD signal intensity, and if so, can we use this signal intensity to distinguish the tumor from the surrounding normal brain? Recent studies have attempted to distinguish brain tumors from normal tissue by using the BOLD fMRI signal intensity; several of these required having animals 3,[24][25][26] or patients 27 breathe carbogen or other hypoxic gases while blood flow was monitored.…”