Hemodynamic Imaging in Cerebral Diffuse Glioma-Part A: Concept, Differential Diagnosis and Tumor Grading

Abstract

Diffuse gliomas are the most common primary malignant intracranial neoplasms. Aside from the challenges pertaining to their treatment-glioblastomas, in particular, have a dismal prognosis and are currently incurable-their pre-operative assessment using standard neuroimaging has several drawbacks, including broad differentials diagnosis, imprecise characterization of tumor subtype and definition of its infiltration in the surrounding brain parenchyma for accurate resection planning. As the pathophysiological alterations of tumor tissue are tightly linked to an aberrant vascularization, advanced hemodynamic imaging, in addition to other innovative approaches, has attracted considerable interest as a means to improve diffuse glioma characterization. In the present part A of our two-review series, the fundamental concepts, techniques and parameters of hemodynamic imaging are discussed in conjunction with their potential role in the differential diagnosis and grading of diffuse gliomas. In particular, recent evidence on dynamic susceptibility contrast, dynamic contrast-enhanced and arterial spin labeling magnetic resonance imaging are reviewed together with perfusion-computed tomography. While these techniques have provided encouraging results in terms of their sensitivity and specificity, the limitations deriving from a lack of standardized acquisition and processing have prevented their widespread clinical adoption, with current efforts aimed at overcoming the existing barriers.

Keywords: MRI; cerebral glioma; cerebrovascular reactivity; glioblastoma; hemodynamic; perfusion MRI; perfusion computed tomography.

Figure 1

Publication per years of different hemodynamic imaging modalities and gliomas. DSC and DCE-MRI have been the subject of more intense research in glioma imaging, followed by ASL-MRI and PCT. IVIM-DWI and BOLD-CVR can also provide different hemodynamic information and in recent years are becoming the focus of active research.

Figure 2

The derivation of perfusion parameters from the signal-response time curve is shown. The signal response time-curve is acquired during contrast bolus passage in the studied region-of-interest. From the signal response time-curve the changes of bolus concentration are estimated (tissue bolus concentration time-curve). Tissue bolus concentration time-curve is processed with mathematical models enabling a qualitative, semi-quantitative or quantitative assessment/measurement of perfusion parameters. Panel (A) Simplified signal response time curve acquired during DSC-MRI. Panel (B) Simplified tissue bolus concentration time-curve. Panel (C) Deconvoluted tissue bolus concentration time-curve to tissue response time-curve. Panel (D) Simplified signal response time-curve acquired during DCE-MRI. Panel (E) Schematic representation of permeability parameters derived from DCE-MRI. (Adapted from Zhang, J.; Liu, H.; Tong, H.; Wang, S.; Yang, Y.; Liu, G.; Zhang, W. Clinical Applications of Contrast-Enhanced Perfusion MRI Techniques in Gliomas: Recent Advances and Current Challenges. Contrast Media Mol. Imaging 2017, 2017, 7064120. https://doi.org/10.1155/2017/7064120). Abbreviations: PH, peak height; PSR, percentage signal recovery; other abbreviations are defined in Table 2.

Figure 3

Cerebrosvascular reactivity. Panel (A) shows a schematic of encroached vasodilatory reserve and downstream of stenosis. Upon vasodilatory stimulus, all vessels will be stimulated to dilate, but flow increase in those with preserved vasodilatory reserve will reduce the flow distal to regional resistance. (Adapted by Sobczyk, O.; Battisti-Charbonney, A.; Fierstra, J.; Mandell, D.M.; Poublanc, J.; Crawley, A.P.; Mikulis, D.J.; Duffin, J.; Fisher, J.A. A conceptual model for CO2-induced redistribution of cerebral blood flow with experimental confirmation using BOLD MRI. NeuroImage 2014, 92, 56–68. ISSN 1053-8119. https://doi.org/10.1016/j.neuroimage.2014.01.051). Panel (B) shows a controlled standardized hypercapnic stimulus and its correlation to BOLD signal change.